jcode + Claude Sonnet 5 on utf16-transcode
2026-07-19 · final +1.2383 · sampled best +1.2561 · 37 grades · jcode v0.51.4-dev (8b39d814e) · full unedited transcript (rendered from the run's agent event log)
user
You are being benchmarked on jcode bench task utf16-transcode, in this directory.
Read spec.md. Your job: make submission/solve.c faster. Correctness on every input is a hard gate, verified by ./grade. Score = log2 doublings of instruction-count improvement over the given implementation, measured deterministically with callgrind.
The loop: edit submission/solve.c (you may add more .c/.h files in submission/), run ./grade, read your score. Grade often; every grade is logged to scores.jsonl as your score-over-time curve.
Rules: edit only files under submission/. Self-contained C17, libc only. Do not modify the grader, verifier, or corpus generator; that voids the run.
Work until you genuinely cannot improve further. Aim as high as you can; +1.0 means 2x, +2.0 means 4x. Report your final score.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat spec.md"}
tool result
# utf16-transcode
Convert UTF-16LE to UTF-8. This is the boundary between JavaScript, Windows, and
Java on one side and the rest of the world on the other: every string crossing it
pays this function.
## Task
You are given a working, tested implementation in `submission/solve.c`.
Make it faster. Correctness on every input is the gate, verified exhaustively
over all code units and pairs plus deep seeded coverage.
```
./grade # build, verify, measure, score
./grade --seed N # reproduce a specific cost corpus
```
Edit only files under `submission/`.
## Contract
```c
// Transcode UTF-16LE code units to UTF-8.
// in: code units, n: count. out: buffer, capacity >= 3*n+4 bytes.
// Returns bytes written, or (size_t)-1 if the input is invalid UTF-16
// (lone surrogate anywhere).
size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);
```
Semantics:
- Code units 0x0000-0xD7FF and 0xE000-0xFFFF encode as 1-3 UTF-8 bytes.
- A high surrogate 0xD800-0xDBFF must be immediately followed by a low
surrogate 0xDC00-0xDFFF; the pair encodes one supplementary code point as
4 bytes. Anything else (lone high, lone low, high at end of input) is
invalid: return (size_t)-1.
- On invalid input the output buffer contents are unspecified.
## Verification (the gate)
1. Every single code unit (65,536 cases).
2. Every pair of code units (4.3 billion pairs is too many: all pairs from a
2,namespace-stratified 4,096-unit sample = 16.7M pairs covering every
boundary class x class combination, plus all 2^20 surrogate x surrogate
pairs exactly).
3. Every code unit embedded at positions 0,1,2,3 in valid padding.
4. 200,000 seeded random strings (1-2K units) mixing ASCII runs, BMP text,
surrogate pairs, and injected lone surrogates.
Any mismatch against the reference oracle fails the grade with a counterexample.
## Cost model (the score)
Instructions inside `utf16_to_utf8` (callgrind) over a seeded ~1M-unit corpus:
ASCII-heavy 40%, Latin/Cyrillic mix 25%, CJK-heavy 20%, emoji/supplementary 15%.
Paired against the frozen given implementation on the same corpus.
```
score = log2(given_cost / your_cost)
```
## Rules
- Self-contained C17, libc only.
- Do not modify the grader/verifier. Any correct program is a valid submission.
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat submission/solve.c && echo --- && ls"}
tool result
// solve.c — the given implementation of utf16_to_utf8.
// A clean, correct scalar transcoder of the kind found in mainstream
// libraries. Make it faster. See ../spec.md. Grade with ../grade.
#include <stdint.h>
#include <stddef.h>
#define INVALID ((size_t)-1)
size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {
size_t o = 0;
for (size_t i = 0; i < n; i++) {
uint32_t c = in[i];
if (c < 0x80) {
out[o++] = (uint8_t)c;
} else if (c < 0x800) {
out[o++] = (uint8_t)(0xC0 | (c >> 6));
out[o++] = (uint8_t)(0x80 | (c & 0x3F));
} else if (c < 0xD800 || c >= 0xE000) {
out[o++] = (uint8_t)(0xE0 | (c >> 12));
out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));
out[o++] = (uint8_t)(0x80 | (c & 0x3F));
} else if (c < 0xDC00) {
// high surrogate: need a low surrogate next
if (i + 1 >= n) return INVALID;
uint32_t lo = in[i + 1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
i++;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
out[o++] = (uint8_t)(0xF0 | (cp >> 18));
out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));
out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));
out[o++] = (uint8_t)(0x80 | (cp & 0x3F));
} else {
return INVALID; // lone low surrogate
}
}
return o;
}
---
grade
scores.jsonl
spec.md
submission
verify
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat grade | head -100"}
tool result
#!/usr/bin/env python3
import os, sys
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "..", "harness"))
from grade import main
main(os.path.dirname(os.path.abspath(__file__)), "utf16_to_utf8")
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "find / -path /proc -prune -o -name \"grade.py\" -print 2>/dev/null"}
tool result
/opt/jcode-bench/harness/grade.py
/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/harness/grade.py
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /opt/jcode-bench/harness/grade.py"}
tool result
#!/usr/bin/env python3
"""Shared grader for jcode bench tasks.
Pipeline: build -> verify (gate) -> callgrind cost (submission + frozen given,
same corpus: paired) -> score = log2(given/sub). Appends to scores.jsonl.
Each task directory provides: submission/*.c, verify/verify.c (+reference.c
optional), verify/given.c (frozen given impl, function prefixed given_),
verify/runner.c (honors -DRUNNER_GIVEN), verify/gen_corpus.py, and a small
`grade` wrapper exporting TASK_FN (the measured function name).
"""
import argparse, json, math, os, re, subprocess, sys, time, glob
def sh(cmd, **kw):
return subprocess.run(cmd, check=True, capture_output=True, text=True, **kw)
def main(here, fn, extra_cflags=None, verify_args=None):
SUB = os.path.join(here, "submission")
VER = os.path.join(here, "verify")
BUILD = os.path.join(here, ".build")
CFLAGS = ["-O2", "-std=c17", "-fno-lto", "-g"] + (extra_cflags or [])
ap = argparse.ArgumentParser()
ap.add_argument("--seed", type=int, default=None)
ap.add_argument("--full", action="store_true",
help="run the full exhaustive gate (if the task has one)")
ap.add_argument("--quiet", action="store_true")
args = ap.parse_args()
seed = args.seed if args.seed is not None else int(time.time()) % 100000
os.makedirs(BUILD, exist_ok=True)
sub_srcs = sorted(glob.glob(os.path.join(SUB, "*.c")))
if not sub_srcs:
sys.exit("no .c files in submission/")
t0 = time.time()
ref = os.path.join(VER, "reference.c")
refs = [ref] if os.path.exists(ref) else []
sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs, *refs,
os.path.join(VER, "verify.c"), "-o", os.path.join(BUILD, "verify"),
"-lm", "-lpthread"])
sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs,
os.path.join(VER, "runner.c"), "-o", os.path.join(BUILD, "runner"), "-lm"])
if not os.path.exists(os.path.join(BUILD, "runner_given")):
sh(["cc", *CFLAGS, "-DRUNNER_GIVEN",
os.path.join(VER, "given.c"), os.path.join(VER, "runner.c"),
"-o", os.path.join(BUILD, "runner_given"), "-lm"])
t_build = time.time() - t0
t0 = time.time()
vargs = [str(seed)] + (["--full"] if args.full else []) + (verify_args or [])
r = subprocess.run([os.path.join(BUILD, "verify"), *vargs],
capture_output=True, text=True)
if r.returncode != 0:
print(r.stdout, end="")
print(r.stderr, end="", file=sys.stderr)
print("grade: FAIL (verification)")
sys.exit(1)
t_verify = time.time() - t0
def measure(binary, func):
corpus = os.path.join(BUILD, f"corpus_{seed}.bin")
if not os.path.exists(corpus):
sh(["python3", os.path.join(VER, "gen_corpus.py"), str(seed), corpus])
cg = os.path.join(BUILD, f"callgrind.{binary}.out")
if os.path.exists(cg):
os.unlink(cg)
sh(["valgrind", "--tool=callgrind", f"--toggle-collect={func}",
"--collect-atstart=no", "--dump-line=no",
f"--callgrind-out-file={cg}", os.path.join(BUILD, binary), corpus])
total = 0
with open(cg) as f:
for line in f:
ls = line.strip()
if re.match(r"^\d+ \d+$", ls) or re.match(r"^\d+ \d+ ", ls):
total += int(ls.split()[1])
if total == 0:
sys.exit(f"cost extraction failed (did you rename {func}?)")
return total
t0 = time.time()
cost = measure("runner", fn)
# The given binary is frozen, so its cost per corpus seed is a pure
# function of the seed: cache it.
gcache = os.path.join(BUILD, f"given_cost_{seed}.json")
if os.path.exists(gcache):
with open(gcache) as f:
given = json.load(f)["cost"]
else:
given = measure("runner_given", f"given_{fn}")
with open(gcache, "w") as f:
json.dump({"cost": given}, f)
t_measure = time.time() - t0
score = math.log2(given / cost)
rec = {"ts": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
"seed": seed, "cost": cost, "given_cost": given,
"score": round(score, 4), "full_gate": bool(args.full)}
with open(os.path.join(here, "scores.jsonl"), "a") as f:
f.write(json.dumps(rec) + "\n")
if not args.quiet:
print(f"build {t_build:5.1f}s")
print(f"verify {t_verify:5.1f}s PASS{' (FULL gate)' if args.full else ''}")
print(f"measure {t_measure:5.1f}s {cost:,} instructions (given: {given:,})")
print(f"SCORE {score:+.4f} ({given / cost:.3f}x)")
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat verify/gen_corpus.py"}
tool result
#!/usr/bin/env python3
"""gen_corpus.py — cost corpus for utf16-transcode (~1M units total).
Regimes: ascii 40%, latin/cyrillic 25%, cjk 20%, emoji/supplementary 15%.
Record format: u32 unit count, then u16le units. All records valid UTF-16.
Usage: gen_corpus.py SEED OUTFILE"""
import random, struct, sys
def gen_record(rng, regime, units):
out = []
while len(out) < units:
if regime == "ascii":
out.extend(rng.randrange(0x20, 0x7F) for _ in range(rng.randrange(20, 80)))
elif regime == "latin":
r = rng.random()
if r < 0.5:
out.extend(rng.randrange(0x20, 0x7F) for _ in range(rng.randrange(2, 10)))
else:
out.extend(rng.randrange(0x80, 0x800) for _ in range(rng.randrange(2, 12)))
elif regime == "cjk":
r = rng.random()
if r < 0.25:
out.extend(rng.randrange(0x20, 0x7F) for _ in range(rng.randrange(1, 6)))
else:
out.extend(rng.randrange(0x4E00, 0x9FFF) for _ in range(rng.randrange(4, 20)))
else: # emoji
r = rng.random()
if r < 0.4:
out.extend(rng.randrange(0x20, 0x7F) for _ in range(rng.randrange(1, 8)))
else:
for _ in range(rng.randrange(1, 6)):
cp = rng.randrange(0x10000, 0x110000)
cp -= 0x10000
out.append(0xD800 + (cp >> 10))
out.append(0xDC00 + (cp & 0x3FF))
return out[:units + 1] if len(out) > units and 0xD800 <= out[units - 1] <= 0xDBFF else out[:units]
def main():
seed, path = int(sys.argv[1]), sys.argv[2]
rng = random.Random(seed)
plan = [("ascii", 40), ("latin", 25), ("cjk", 20), ("emoji", 15)]
records = []
for regime, share in plan:
total = share * 10000
done = 0
while done < total:
units = rng.randrange(500, 3000)
rec = gen_record(rng, regime, units)
# ensure no trailing lone high surrogate
if rec and 0xD800 <= rec[-1] <= 0xDBFF:
rec.pop()
records.append(rec)
done += len(rec)
rng.shuffle(records)
with open(path, "wb") as f:
for rec in records:
f.write(struct.pack("<I", len(rec)))
f.write(struct.pack(f"<{len(rec)}H", *rec))
print(f"corpus: {len(records)} records, {sum(len(r) for r in records)} units, seed {seed}")
if __name__ == "__main__":
main()
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat verify/runner.c verify/given.c 2>/dev/null | head -80"}
tool result
// runner.c — cost driver for utf16-transcode. Corpus: u32 count then u16 units
// per record. Run under callgrind with --toggle-collect.
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef RUNNER_GIVEN
size_t given_utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);
#define utf16_to_utf8 given_utf16_to_utf8
#else
size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);
#endif
int main(int argc, char **argv) {
if (argc < 2) { fprintf(stderr, "usage: runner CORPUS\n"); return 2; }
FILE *f = fopen(argv[1], "rb");
if (!f) { perror("corpus"); return 2; }
fseek(f, 0, SEEK_END); long sz = ftell(f); fseek(f, 0, SEEK_SET);
uint8_t *data = malloc((size_t)sz);
if (fread(data, 1, (size_t)sz, f) != (size_t)sz) { perror("read"); return 2; }
fclose(f);
uint8_t *out = malloc(3u * (1u << 21) + 64);
unsigned long long checksum = 0, nrec = 0;
size_t off = 0;
while (off + 4 <= (size_t)sz) {
uint32_t cnt; memcpy(&cnt, data + off, 4); off += 4;
if (off + 2ull * cnt > (size_t)sz) { fprintf(stderr, "corrupt corpus\n"); return 2; }
size_t r = utf16_to_utf8((const uint16_t *)(data + off), cnt, out);
if (r == (size_t)-1) { fprintf(stderr, "BUG: corpus record rejected\n"); return 3; }
for (size_t k = 0; k < r; k += 64) checksum += out[k];
checksum += r; nrec++;
off += 2ull * cnt;
}
printf("runner: %llu records, checksum %llu\n", nrec, checksum);
return 0;
}
// solve.c — the given implementation of utf16_to_utf8.
// A clean, correct scalar transcoder of the kind found in mainstream
// libraries. Make it faster. See ../spec.md. Grade with ../grade.
#include <stdint.h>
#include <stddef.h>
#define INVALID ((size_t)-1)
size_t given_utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {
size_t o = 0;
for (size_t i = 0; i < n; i++) {
uint32_t c = in[i];
if (c < 0x80) {
out[o++] = (uint8_t)c;
} else if (c < 0x800) {
out[o++] = (uint8_t)(0xC0 | (c >> 6));
out[o++] = (uint8_t)(0x80 | (c & 0x3F));
} else if (c < 0xD800 || c >= 0xE000) {
out[o++] = (uint8_t)(0xE0 | (c >> 12));
out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));
out[o++] = (uint8_t)(0x80 | (c & 0x3F));
} else if (c < 0xDC00) {
// high surrogate: need a low surrogate next
if (i + 1 >= n) return INVALID;
uint32_t lo = in[i + 1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
i++;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
out[o++] = (uint8_t)(0xF0 | (cp >> 18));
out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));
out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));
out[o++] = (uint8_t)(0x80 | (cp & 0x3F));
} else {
return INVALID; // lone low surrogate
}
}
return o;
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /proc/cpuinfo | grep -m1 flags; nproc"}
tool result
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy svm cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw topoext fsgsbase bmi1 avx2 smep bmi2 erms invpcid avx512f avx512dq rdseed adx smap clwb avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves avx512vbmi umip avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq rdpid fsrm
4
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cc --version; echo ---; cc -dM -E -x c /dev/null | grep -i avx"}
tool result
cc (GCC) 16.1.1 20260625
Copyright (C) 2026 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
---
--- Command finished with exit code: 1 ---
Exit code: 1
tool call: bash
{"command": "valgrind --version"}
tool result
valgrind-3.25.1
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 0.5s
verify 2.0s PASS
measure 6.2s 78,181,481 instructions (given: 78,181,481)
SCORE +0.0000 (1.000x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/test_target.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n__attribute__((target(\"avx2\")))\nint foo(__m256i *p) {\n __m256i v = _mm256_loadu_si256(p);\n __m256i r = _mm256_add_epi32(v,v);\n _mm256_storeu_si256(p, r);\n return 0;\n}\nEOF\ncc -O2 -std=c17 -fno-lto -g -c /tmp/test_target.c -o /tmp/test_target.o && echo OK\nobjdump -d /tmp/test_target.o | grep -i vpadd"}
tool result
OK
6: c5 fd fe c0 vpaddd %ymm0,%ymm0,%ymm0
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/avx2test.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n__attribute__((target(\"avx2\")))\nint main(void) {\n __m256i a = _mm256_set1_epi16(5);\n __m256i b = _mm256_add_epi16(a,a);\n int16_t buf[16];\n _mm256_storeu_si256((__m256i*)buf, b);\n printf(\"%d\\n\", buf[0]);\n __m128i x = _mm_setzero_si128();\n __m128i idx = _mm_set1_epi8(0);\n __m128i y = _mm_shuffle_epi8(x, idx);\n (void)y;\n return 0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/avx2test /tmp/avx2test.c\nvalgrind --tool=callgrind --toggle-collect=main --collect-atstart=no /tmp/avx2test 2>&1 | tail -30"}
tool result
/tmp/avx2test.c: In function ‘main’:
/tmp/avx2test.c:7:5: error: unknown type name ‘int16_t’
7 | int16_t buf[16];
| ^~~~~~~
/tmp/avx2test.c:3:1: note: ‘int16_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’
2 | #include <stdio.h>
+++ |+#include <stdint.h>
3 | __attribute__((target("avx2")))
valgrind: /tmp/avx2test: No such file or directory
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -i '2a #include <stdint.h>' /tmp/avx2test.c\ncc -O2 -std=c17 -o /tmp/avx2test /tmp/avx2test.c\n/tmp/avx2test\nvalgrind --tool=callgrind --toggle-collect=main --collect-atstart=no /tmp/avx2test 2>&1 | tail -30"}
tool result
10
==329== Callgrind, a call-graph generating cache profiler
==329== Copyright (C) 2002-2017, and GNU GPL'd, by Josef Weidendorfer et al.
==329== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info
==329== Command: /tmp/avx2test
==329==
==329== For interactive control, run 'callgrind_control -h'.
10
==329==
==329== Events : Ir
==329== Collected : 1908
==329==
==329== I refs: 1,908
--- Command finished with exit code: 0 ---
assistant
Good, AVX2 works under callgrind (Valgrind supports AVX2 emulation on this host CPU which has avx512). Let's check if valgrind supports AVX-512 too, but AVX2 is likely plenty. Let's design a vectorized implementation.
tool call: bash
{"command": "cat > /tmp/avx512test.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <stdint.h>\n__attribute__((target(\"avx512bw,avx512vl\")))\nint main(void) {\n __m256i a = _mm256_set1_epi16(5);\n __mmask16 m = _mm256_cmpgt_epi16_mask(a, _mm256_setzero_si256());\n printf(\"%d\\n\", (int)m);\n return 0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/avx512test /tmp/avx512test.c && /tmp/avx512test\nvalgrind --tool=callgrind --toggle-collect=main --collect-atstart=no /tmp/avx512test 2>&1 | tail -10"}
tool result
65535
==355== probably kill your program.
==355==
==355== Process terminating with default action of signal 4 (SIGILL): dumping core
==355== Illegal opcode at address 0x4001051
==355== at 0x4001051: main (in /tmp/avx512test)
==355==
==355== Events : Ir
==355== Collected : 0
==355==
==355== I refs: 0
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "ls /opt/jcode-bench/ ; find /opt/jcode-bench -iname \"*.md\" | xargs grep -l \"immintrin\\|SIMD\\|libc only\" 2>/dev/null"}
tool result
README.md
aws
harness
modal
tasks
/opt/jcode-bench/tasks/utf16-transcode/spec.md
/opt/jcode-bench/tasks/float-print/spec.md
/opt/jcode-bench/tasks/json-unescape/spec.md
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat verify/verify.c | head -60"}
tool result
// verify.c — exhaustive correctness gate for utf16-transcode.
// 1. every single code unit
// 2. all pairs from a boundary-stratified sample x sample (16.7M),
// plus ALL surrogate x surrogate pairs (2^20) exactly
// 3. every code unit at positions 0..3 inside valid padding
// 4. 200k seeded random strings across regimes with injected lone surrogates
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <stdatomic.h>
size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);
size_t ref_utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);
#define INVALID ((size_t)-1)
static atomic_ullong n_cases;
static atomic_int failed;
static pthread_mutex_t report_mu = PTHREAD_MUTEX_INITIALIZER;
static void fail_report(const uint16_t *in, size_t n, const char *stage) {
pthread_mutex_lock(&report_mu);
if (!atomic_exchange(&failed, 1)) {
fprintf(stderr, "MISMATCH (%s) on %zu units:", stage, n);
for (size_t i = 0; i < n && i < 24; i++) fprintf(stderr, " %04x", in[i]);
fprintf(stderr, "\n");
}
pthread_mutex_unlock(&report_mu);
}
static int check(const uint16_t *in, size_t n, uint8_t *bs, uint8_t *br, const char *stage) {
memset(bs, 0xAA, 3 * n + 8);
memset(br, 0x55, 3 * n + 8);
size_t rs = utf16_to_utf8(in, n, bs);
size_t rr = ref_utf16_to_utf8(in, n, br);
atomic_fetch_add_explicit(&n_cases, 1, memory_order_relaxed);
if (rs != rr || (rr != INVALID && memcmp(bs, br, rr) != 0)) {
fail_report(in, n, stage);
return 0;
}
return 1;
}
// boundary-stratified sample of code units: all class edges + strided interior
static uint16_t sample[4096];
static size_t n_sample;
static void build_sample(void) {
size_t k = 0;
// all boundaries +-2
static const uint32_t EDGE[] = {0x0000,0x007F,0x0080,0x07FF,0x0800,
0xD7FF,0xD800,0xDBFF,0xDC00,0xDFFF,0xE000,0xFFFF};
for (size_t e = 0; e < sizeof(EDGE)/sizeof(EDGE[0]); e++)
for (int d = -2; d <= 2; d++) {
int64_t v = (int64_t)EDGE[e] + d;
if (v >= 0 && v <= 0xFFFF) sample[k++] = (uint16_t)v;
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/cpusup.c << 'EOF'\n#include <stdio.h>\nint main(void){\n printf(\"%d\\n\", __builtin_cpu_supports(\"avx2\"));\n return 0;\n}\nEOF\ncc -O2 -o /tmp/cpusup /tmp/cpusup.c && /tmp/cpusup"}
tool result
1024
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/t2.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n__attribute__((target(\"avx2\")))\nstatic void foo(const uint16_t *in, uint8_t *out) {\n __m256i v = _mm256_loadu_si256((const __m256i*)in);\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n __m128i bytes = _mm_packus_epi16(lo, hi);\n _mm_storeu_si128((__m128i*)out, bytes);\n}\nint main(void){ uint16_t in[16]={0}; uint8_t out[16]; foo(in,out); return out[0]; }\nEOF\ncc -O2 -std=c17 -c /tmp/t2.c -o /tmp/t2.o && echo COMPILE_OK\ncc -O2 -std=c17 /tmp/t2.c -o /tmp/t2 && /tmp/t2; echo \"exit=$?\""}
tool result
COMPILE_OK
exit=0
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat verify/verify.c | sed -n '60,200p'"}
tool result
}
// strided interior coverage
for (uint32_t v = 0; v <= 0xFFFF && k < 4096; v += 17) sample[k++] = (uint16_t)v;
n_sample = k < 4096 ? k : 4096;
}
typedef struct { int tid, nthreads; } targ_t;
static void *pair_worker(void *argp) {
targ_t *a = argp;
uint8_t bs[64], br[64];
uint16_t s[2];
// sample x sample
for (size_t i = a->tid; i < n_sample; i += a->nthreads) {
if (atomic_load_explicit(&failed, memory_order_relaxed)) return NULL;
s[0] = sample[i];
for (size_t j = 0; j < n_sample; j++) {
s[1] = sample[j];
if (!check(s, 2, bs, br, "pair")) return NULL;
}
}
// all surrogate x surrogate pairs
for (uint32_t hi = 0xD800 + a->tid; hi <= 0xDFFF; hi += a->nthreads) {
if (atomic_load_explicit(&failed, memory_order_relaxed)) return NULL;
s[0] = (uint16_t)hi;
for (uint32_t lo = 0xD800; lo <= 0xDFFF; lo++) {
s[1] = (uint16_t)lo;
if (!check(s, 2, bs, br, "surrogate-pair")) return NULL;
}
}
return NULL;
}
static void *single_worker(void *argp) {
targ_t *a = argp;
uint8_t bs[64], br[64];
uint16_t s[8];
for (uint32_t v = a->tid; v <= 0xFFFF; v += a->nthreads) {
if (atomic_load_explicit(&failed, memory_order_relaxed)) return NULL;
s[0] = (uint16_t)v;
if (!check(s, 1, bs, br, "single")) return NULL;
// embedded at positions 0..3 in valid padding 'A', with a trailing pad
for (int pos = 0; pos < 4; pos++) {
size_t n = 5;
for (size_t q = 0; q < n; q++) s[q] = 'A';
s[pos] = (uint16_t)v;
if (!check(s, n, bs, br, "embedded")) return NULL;
}
}
return NULL;
}
// seeded random strings
static uint64_t rng_state;
static uint64_t rng_next(void) {
uint64_t z = (rng_state += 0x9E3779B97F4A7C15ULL);
z = (z ^ (z >> 30)) * 0xBF58476D1CE4E5B9ULL;
z = (z ^ (z >> 27)) * 0x94D049BB133111EBULL;
return z ^ (z >> 31);
}
int main(int argc, char **argv) {
uint64_t seed = 0x6A636F6465ULL;
if (argc > 1 && strcmp(argv[1], "--full") != 0) seed = strtoull(argv[1], NULL, 0);
build_sample();
int nt = 8;
pthread_t th[8];
targ_t args[8];
for (int t = 0; t < nt; t++) { args[t] = (targ_t){t, nt}; pthread_create(&th[t], NULL, single_worker, &args[t]); }
for (int t = 0; t < nt; t++) pthread_join(th[t], NULL);
if (atomic_load(&failed)) return 1;
for (int t = 0; t < nt; t++) pthread_create(&th[t], NULL, pair_worker, &args[t]);
for (int t = 0; t < nt; t++) pthread_join(th[t], NULL);
if (atomic_load(&failed)) return 1;
// random strings (single thread is fine: 200k x ~1.5k units)
rng_state = seed;
static uint16_t s[2048];
static uint8_t bs[3 * 2048 + 16], br[3 * 2048 + 16];
for (int t = 0; t < 200000; t++) {
size_t n = 1 + (size_t)(rng_next() % 1500);
for (size_t i = 0; i < n; i++) {
unsigned r = (unsigned)(rng_next() % 100);
if (r < 40) s[i] = (uint16_t)(rng_next() % 0x80);
else if (r < 60) s[i] = (uint16_t)(0x80 + rng_next() % 0x780);
else if (r < 80) { uint16_t v; do { v = (uint16_t)(0x800 + rng_next() % 0xF800); } while (v >= 0xD800 && v < 0xE000); s[i] = v; }
else if (r < 95 && i + 1 < n) {
s[i] = (uint16_t)(0xD800 + rng_next() % 0x400);
s[++i] = (uint16_t)(0xDC00 + rng_next() % 0x400);
}
else s[i] = (uint16_t)(0xD800 + rng_next() % 0x800); // often lone surrogate
}
if (!check(s, n, bs, br, "random")) return 1;
}
printf("verify: PASS (%llu cases)\n", (unsigned long long)atomic_load(&n_cases));
return 0;
}
--- Command finished with exit code: 0 ---
tool call: write
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "content": "// solve.c \u2014 optimized utf16_to_utf8.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < n) {\n if (i + 4 <= n) {\n uint64_t w;\n memcpy(&w, in + i, 8);\n if ((w & 0xFF80FF80FF80FF80ULL) == 0) {\n out[o + 0] = (uint8_t)(w);\n out[o + 1] = (uint8_t)(w >> 16);\n out[o + 2] = (uint8_t)(w >> 32);\n out[o + 3] = (uint8_t)(w >> 48);\n o += 4;\n i += 4;\n continue;\n }\n }\n uint32_t c = in[i];\n if (c < 0x80) {\n out[o++] = (uint8_t)c;\n i++;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n i += 2;\n } else {\n return INVALID;\n }\n }\n return o;\n}\n"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (52 lines):
1- // solve.c — the given implementation of utf16_to_utf8.
2- // A clean, correct scalar transcoder of the kind found in mainstream
3- // libraries. Make it faster. See ../spec.md. Grade with ../grade.
1+ // solve.c — optimized utf16_to_utf8.
4+ #include <string.h>
10- size_t o = 0;
11- for (size_t i = 0; i < n; i++) {
9+ size_t i = 0, o = 0;
10+ while (i < n) {
11+ if (i + 4 <= n) {
12+ uint64_t w;
13+ memcpy(&w, in + i, 8);
14+ if ((w & 0xFF80FF80FF80FF80ULL) == 0) {
15+ out[o + 0] = (uint8_t)(w);
16+ out[o + 1] = (uint8_t)(w >> 16);
17+ out[o + 2] = (uint8_t)(w >> 32);
18+ out[o + 3] = (uint8_t)(w >> 48);
19+ o += 4;
20+ i += 4;
21+ continue;
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 0.5s
verify 1.9s PASS
measure 0.5s 80,229,466 instructions (given: 78,181,481)
SCORE -0.0373 (0.974x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat verify/verify.c | grep -n \"pthread\\|nthreads\" | head -5\nnproc"}
tool result
12:#include <pthread.h>
22:static pthread_mutex_t report_mu = PTHREAD_MUTEX_INITIALIZER;
25: pthread_mutex_lock(&report_mu);
31: pthread_mutex_unlock(&report_mu);
66:typedef struct { int tid, nthreads; } targ_t;
4
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "mkdir -p /tmp/jt && cat > /tmp/jt/ref.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#define INVALID ((size_t)-1)\nsize_t ref_utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t o = 0;\n for (size_t i = 0; i < n; i++) {\n uint32_t c = in[i];\n if (c < 0x80) {\n out[o++] = (uint8_t)c;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n i++;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n } else {\n return INVALID;\n }\n }\n return o;\n}\nEOF\necho done"}
tool result
done
--- Command finished with exit code: 0 ---
tool call: write
{"content": "// solve.c \u2014 optimized utf16_to_utf8.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"avx2\")))\nstatic inline size_t ascii_run(const uint16_t *in, size_t n, size_t i, uint8_t *out, size_t o) {\n // Try to consume as many ASCII units as possible in 16-wide chunks.\n while (i + 16 <= n) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n __m256i hib = _mm256_set1_epi16((short)0xFF80);\n __m256i masked = _mm256_and_si256(v, hib);\n if (!_mm256_testz_si256(masked, masked)) break;\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n __m128i packed = _mm_packus_epi16(lo, hi);\n _mm_storeu_si128((__m128i *)(out + o), packed);\n i += 16;\n o += 16;\n }\n return (i << 32) | o; // pack both into return; caller unpacks (n,o both < 2^32 in practice)\n}\n\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < n) {\n uint32_t c = in[i];\n if (c < 0x80) {\n if (i + 16 <= n) {\n uint64_t packed = ascii_run(in, n, i, out, o);\n size_t ni = packed >> 32, no = packed & 0xFFFFFFFFu;\n if (ni != i) { i = ni; o = no; continue; }\n }\n out[o++] = (uint8_t)c;\n i++;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n i += 2;\n } else {\n return INVALID;\n }\n }\n return o;\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (63 lines):
5+ #include <immintrin.h>
9+ __attribute__((target("avx2")))
10+ static inline size_t ascii_run(const uint16_t *in, size_t n, size_t i, uint8_t *out, size_t o) {
11+ // Try to consume as many ASCII units as possible in 16-wide chunks.
12+ while (i + 16 <= n) {
13+ __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));
14+ __m256i hib = _mm256_set1_epi16((short)0xFF80);
15+ __m256i masked = _mm256_and_si256(v, hib);
16+ if (!_mm256_testz_si256(masked, masked)) break;
17+ __m128i lo = _mm256_castsi256_si128(v);
18+ __m128i hi = _mm256_extracti128_si256(v, 1);
19+ __m128i packed = _mm_packus_epi16(lo, hi);
20+ _mm_storeu_si128((__m128i *)(out + o), packed);
21+ i += 16;
22+ o += 16;
23+ }
24+ return (i << 32) | o; // pack both into return; caller unpacks (n,o both < 2^32 in practice)
25+ }
11- if (i + 4 <= n) {
12- uint64_t w;
...
tool call: write
{"content": "// solve.c \u2014 optimized utf16_to_utf8.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"avx2\")))\nstatic inline void ascii_run(const uint16_t *in, size_t n, size_t *ip, uint8_t *out, size_t *op) {\n size_t i = *ip, o = *op;\n while (i + 16 <= n) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n __m256i hib = _mm256_set1_epi16((short)0xFF80);\n __m256i masked = _mm256_and_si256(v, hib);\n if (!_mm256_testz_si256(masked, masked)) break;\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n __m128i packed = _mm_packus_epi16(lo, hi);\n _mm_storeu_si128((__m128i *)(out + o), packed);\n i += 16;\n o += 16;\n }\n *ip = i; *op = o;\n}\n\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < n) {\n uint32_t c = in[i];\n if (c < 0x80) {\n if (i + 16 <= n) {\n size_t oi = i;\n ascii_run(in, n, &i, out, &o);\n if (i != oi) continue;\n }\n out[o++] = (uint8_t)c;\n i++;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n i += 2;\n } else {\n return INVALID;\n }\n }\n return o;\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (63 lines):
10- static inline size_t ascii_run(const uint16_t *in, size_t n, size_t i, uint8_t *out, size_t o) {
11- // Try to consume as many ASCII units as possible in 16-wide chunks.
10+ static inline void ascii_run(const uint16_t *in, size_t n, size_t *ip, uint8_t *out, size_t *op) {
11+ size_t i = *ip, o = *op;
24- return (i << 32) | o; // pack both into return; caller unpacks (n,o both < 2^32 in practice)
24+ *ip = i; *op = o;
33- uint64_t packed = ascii_run(in, n, i, out, o);
34- size_t ni = packed >> 32, no = packed & 0xFFFFFFFFu;
35- if (ni != i) { i = ni; o = no; continue; }
33+ size_t oi = i;
34+ ascii_run(in, n, &i, out, &o);
35+ if (i != oi) continue;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 1.3s
verify 1.9s PASS
measure 0.5s 83,139,188 instructions (given: 78,181,481)
SCORE -0.0887 (0.940x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d .build/runner | grep -A 100 \"<utf16_to_utf8>:\" | head -150"}
tool result
0000000000001510 <utf16_to_utf8>:
1510: 48 83 ec 38 sub $0x38,%rsp
1514: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
151b: 00 00
151d: 48 89 44 24 18 mov %rax,0x18(%rsp)
1522: 31 c0 xor %eax,%eax
1524: 48 c7 44 24 08 00 00 movq $0x0,0x8(%rsp)
152b: 00 00
152d: 48 c7 44 24 10 00 00 movq $0x0,0x10(%rsp)
1534: 00 00
1536: 48 85 f6 test %rsi,%rsi
1539: 0f 84 e6 01 00 00 je 1725 <utf16_to_utf8+0x215>
153f: 48 89 6c 24 30 mov %rbp,0x30(%rsp)
1544: 45 31 db xor %r11d,%r11d
1547: 48 89 d5 mov %rdx,%rbp
154a: 48 89 5c 24 28 mov %rbx,0x28(%rsp)
154f: eb 39 jmp 158a <utf16_to_utf8+0x7a>
1551: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
1558: 49 8d 43 10 lea 0x10(%r11),%rax
155c: 48 39 c6 cmp %rax,%rsi
155f: 0f 83 eb 00 00 00 jae 1650 <utf16_to_utf8+0x140>
1565: 4c 8b 5c 24 08 mov 0x8(%rsp),%r11
156a: 48 8b 44 24 10 mov 0x10(%rsp),%rax
156f: 49 83 c3 01 add $0x1,%r11
1573: 4c 89 5c 24 08 mov %r11,0x8(%rsp)
1578: 48 8d 50 01 lea 0x1(%rax),%rdx
157c: 88 5c 05 00 mov %bl,0x0(%rbp,%rax,1)
1580: 48 89 54 24 10 mov %rdx,0x10(%rsp)
1585: 49 39 f3 cmp %rsi,%r11
1588: 73 48 jae 15d2 <utf16_to_utf8+0xc2>
158a: 42 0f b7 04 5f movzwl (%rdi,%r11,2),%eax
158f: 4b 8d 0c 1b lea (%r11,%r11,1),%rcx
1593: 89 c3 mov %eax,%ebx
1595: 66 83 f8 7f cmp $0x7f,%ax
1599: 76 bd jbe 1558 <utf16_to_utf8+0x48>
159b: 3d ff 07 00 00 cmp $0x7ff,%eax
15a0: 77 5e ja 1600 <utf16_to_utf8+0xf0>
15a2: 48 8b 54 24 10 mov 0x10(%rsp),%rdx
15a7: c1 e8 06 shr $0x6,%eax
15aa: 83 e3 3f and $0x3f,%ebx
15ad: 49 83 c3 01 add $0x1,%r11
15b1: 83 c8 c0 or $0xffffffc0,%eax
15b4: 83 cb 80 or $0xffffff80,%ebx
15b7: 4c 89 5c 24 08 mov %r11,0x8(%rsp)
15bc: 88 44 15 00 mov %al,0x0(%rbp,%rdx,1)
15c0: 48 8d 42 02 lea 0x2(%rdx),%rax
15c4: 48 89 44 24 10 mov %rax,0x10(%rsp)
15c9: 88 5c 15 01 mov %bl,0x1(%rbp,%rdx,1)
15cd: 49 39 f3 cmp %rsi,%r11
15d0: 72 b8 jb 158a <utf16_to_utf8+0x7a>
15d2: 48 8b 44 24 10 mov 0x10(%rsp),%rax
15d7: 48 8b 5c 24 28 mov 0x28(%rsp),%rbx
15dc: 48 8b 6c 24 30 mov 0x30(%rsp),%rbp
15e1: 48 8b 54 24 18 mov 0x18(%rsp),%rdx
15e6: 64 48 2b 14 25 28 00 sub %fs:0x28,%rdx
15ed: 00 00
15ef: 0f 85 37 01 00 00 jne 172c <utf16_to_utf8+0x21c>
15f5: 48 83 c4 38 add $0x38,%rsp
15f9: c3 ret
15fa: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
1600: 8d 90 00 28 ff ff lea -0xd800(%rax),%edx
1606: 81 fa ff 07 00 00 cmp $0x7ff,%edx
160c: 76 72 jbe 1680 <utf16_to_utf8+0x170>
160e: 89 c1 mov %eax,%ecx
1610: c1 e8 06 shr $0x6,%eax
1613: 48 8b 54 24 10 mov 0x10(%rsp),%rdx
1618: 83 e3 3f and $0x3f,%ebx
161b: 83 e0 3f and $0x3f,%eax
161e: c1 e9 0c shr $0xc,%ecx
1621: 83 cb 80 or $0xffffff80,%ebx
1624: 49 83 c3 01 add $0x1,%r11
1628: 83 c8 80 or $0xffffff80,%eax
162b: 83 c9 e0 or $0xffffffe0,%ecx
162e: 88 5c 15 02 mov %bl,0x2(%rbp,%rdx,1)
1632: 88 44 15 01 mov %al,0x1(%rbp,%rdx,1)
1636: 48 8d 42 03 lea 0x3(%rdx),%rax
163a: 88 4c 15 00 mov %cl,0x0(%rbp,%rdx,1)
163e: 48 89 44 24 10 mov %rax,0x10(%rsp)
1643: 4c 89 5c 24 08 mov %r11,0x8(%rsp)
1648: e9 38 ff ff ff jmp 1585 <utf16_to_utf8+0x75>
164d: 0f 1f 00 nopl (%rax)
1650: 48 8d 54 24 08 lea 0x8(%rsp),%rdx
1655: 4c 8d 44 24 10 lea 0x10(%rsp),%r8
165a: 48 89 e9 mov %rbp,%rcx
165d: e8 1e fe ff ff call 1480 <ascii_run>
1662: 48 8b 44 24 08 mov 0x8(%rsp),%rax
1667: 4c 39 d8 cmp %r11,%rax
166a: 0f 84 fa fe ff ff je 156a <utf16_to_utf8+0x5a>
1670: 49 89 c3 mov %rax,%r11
1673: e9 0d ff ff ff jmp 1585 <utf16_to_utf8+0x75>
1678: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
167f: 00
1680: 3d ff db 00 00 cmp $0xdbff,%eax
1685: 0f 87 84 00 00 00 ja 170f <utf16_to_utf8+0x1ff>
168b: 49 8d 43 01 lea 0x1(%r11),%rax
168f: 48 39 f0 cmp %rsi,%rax
1692: 73 7b jae 170f <utf16_to_utf8+0x1ff>
1694: 0f b7 44 0f 02 movzwl 0x2(%rdi,%rcx,1),%eax
1699: 8d 88 00 24 ff ff lea -0xdc00(%rax),%ecx
169f: 81 f9 ff 03 00 00 cmp $0x3ff,%ecx
16a5: 77 68 ja 170f <utf16_to_utf8+0x1ff>
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && python3 -c \"\nimport struct, random\nrng = random.Random(1)\ndef gen(regime, total):\n out=[]\n while len(out)<total:\n if regime=='ascii':\n out.extend(rng.randrange(0x20,0x7F) for _ in range(rng.randrange(20,80)))\n elif regime=='latin':\n r=rng.random()\n if r<0.5: out.extend(rng.randrange(0x20,0x7F) for _ in range(rng.randrange(2,10)))\n else: out.extend(rng.randrange(0x80,0x800) for _ in range(rng.randrange(2,12)))\n elif regime=='cjk':\n r=rng.random()\n if r<0.25: out.extend(rng.randrange(0x20,0x7F) for _ in range(rng.randrange(1,6)))\n else: out.extend(rng.randrange(0x4E00,0x9FFF) for _ in range(rng.randrange(4,20)))\n else:\n r=rng.random()\n if r<0.4: out.extend(rng.randrange(0x20,0x7F) for _ in range(rng.randrange(1,8)))\n else:\n for _ in range(rng.randrange(1,6)):\n cp=rng.randrange(0x10000,0x110000)-0x10000\n out.append(0xD800+(cp>>10)); out.append(0xDC00+(cp&0x3FF))\n return out[:total]\nfor regime in ['ascii','latin','cjk','emoji']:\n rec = gen(regime, 200000)\n if rec and 0xD800<=rec[-1]<=0xDBFF: rec.pop()\n with open(f'/tmp/corpus_{regime}.bin','wb') as f:\n f.write(struct.pack('<I', len(rec)))\n f.write(struct.pack(f'<{len(rec)}H', *rec))\nprint('done')\n\"\nls -la /tmp/corpus_*.bin"}
tool result
done
-rw-r--r-- 1 root root 400004 Jul 19 03:13 /tmp/corpus_ascii.bin
-rw-r--r-- 1 root root 400004 Jul 19 03:13 /tmp/corpus_cjk.bin
-rw-r--r-- 1 root root 400002 Jul 19 03:13 /tmp/corpus_emoji.bin
-rw-r--r-- 1 root root 400004 Jul 19 03:13 /tmp/corpus_latin.bin
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && for f in ascii latin cjk emoji; do\n echo \"== $f ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_$f.out .build/runner /tmp/corpus_$f.bin >/dev/null 2>/tmp/err_$f.txt\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii ==
862780
== latin ==
23705212
== cjk ==
30065375
== emoji ==
27680580
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "for f in ascii latin cjk emoji; do\npython3 -c \"\nimport struct\nwith open('/tmp/corpus_$f.bin','rb') as fh:\n data=fh.read()\ncnt = struct.unpack('<I', data[:4])[0]\nprint('$f', cnt)\n\"\ndone"}
tool result
ascii 200000
latin 200000
cjk 200000
emoji 199999
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && for f in ascii latin cjk emoji; do\n echo \"== $f (given) ==\"\n valgrind --tool=callgrind --toggle-collect=given_utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgg_$f.out .build/runner_given /tmp/corpus_$f.bin >/dev/null 2>/tmp/errg_$f.txt\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgg_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (given) ==
10000053
== latin (given) ==
14332733
== cjk (given) ==
25633253
== emoji (given) ==
18650753
--- Command finished with exit code: 0 ---
tool call: write
{"content": "// solve.c \u2014 optimized utf16_to_utf8.\n#include <stdint.h>\n#include <stddef.h>\n#include <immintrin.h>\n\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"avx2\")))\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < n) {\n // Bulk ASCII: 16 units -> 16 bytes.\n if (i + 16 <= n) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n __m256i hib = _mm256_set1_epi16((short)0xFF80);\n if (_mm256_testz_si256(v, hib)) {\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n __m128i packed = _mm_packus_epi16(lo, hi);\n _mm_storeu_si128((__m128i *)(out + o), packed);\n i += 16;\n o += 16;\n continue;\n }\n // Bulk 2-byte: 8 units -> 16 bytes, all in [0x80,0x7FF].\n {\n __m128i v8 = _mm256_castsi256_si128(v);\n __m128i lowmask = _mm_set1_epi16(0x0080);\n __m128i himask = _mm_set1_epi16((short)0xF800);\n // in range [0x80,0x7FF] iff (c - 0x80) < 0x780 unsigned\n __m128i shifted = _mm_sub_epi16(v8, lowmask);\n __m128i limit = _mm_set1_epi16((short)0x0780 - 1);\n // unsigned compare via xor sign bit trick\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i sa = _mm_xor_si128(shifted, sbit);\n __m128i sb = _mm_xor_si128(limit, sbit);\n __m128i inrange = _mm_cmpgt_epi16(sb, sa); // shifted <= limit unsigned equiv: sb > sa means limit>shifted... need <=\n // inrange currently: limit_signed > shifted_signed <=> unsigned shifted < 0x780 (since limit=0x77F, want shifted<=0x77F i.e. <0x780)\n if (_mm_movemask_epi8(inrange) == 0xFFFF) {\n __m128i hipart = _mm_srli_epi16(v8, 6);\n hipart = _mm_or_si128(hipart, _mm_set1_epi16((short)0xFFC0));\n __m128i lopart = _mm_and_si128(v8, _mm_set1_epi16(0x3F));\n lopart = _mm_or_si128(lopart, _mm_set1_epi16((short)0xFF80));\n __m128i hib8 = _mm_packus_epi16(hipart, hipart);\n __m128i lob8 = _mm_packus_epi16(lopart, lopart);\n __m128i inter = _mm_unpacklo_epi8(hib8, lob8);\n _mm_storeu_si128((__m128i *)(out + o), inter);\n i += 8;\n o += 16;\n continue;\n }\n }\n }\n uint32_t c = in[i];\n if (c < 0x80) {\n out[o++] = (uint8_t)c;\n i++;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n i += 2;\n } else {\n return INVALID;\n }\n }\n return o;\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (82 lines):
4- #include <string.h>
10- static inline void ascii_run(const uint16_t *in, size_t n, size_t *ip, uint8_t *out, size_t *op) {
11- size_t i = *ip, o = *op;
12- while (i + 16 <= n) {
13- __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));
14- __m256i hib = _mm256_set1_epi16((short)0xFF80);
15- __m256i masked = _mm256_and_si256(v, hib);
16- if (!_mm256_testz_si256(masked, masked)) break;
17- __m128i lo = _mm256_castsi256_si128(v);
18- __m128i hi = _mm256_extracti128_si256(v, 1);
19- __m128i packed = _mm_packus_epi16(lo, hi);
20- _mm_storeu_si128((__m128i *)(out + o), packed);
21- i += 16;
22- o += 16;
23- }
24- *ip = i; *op = o;
25- }
12+ // Bulk ASCII: 16 units -> 16 bytes.
13+ if (i + 16 <= n) {
14+ __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 1.2s
verify 2.0s PASS
measure 0.5s 82,866,809 instructions (given: 78,181,481)
SCORE -0.0840 (0.943x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_mine -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (mine) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgm_$f.out /tmp/runner_mine /tmp/corpus_$f.bin >/dev/null 2>/tmp/errm_$f.txt\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgm_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (mine) ==
1200103
== latin (mine) ==
14101561
== cjk (mine) ==
41404853
== emoji (mine) ==
27818228
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/solve_v1.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#define INVALID ((size_t)-1)\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < n) {\n if (i + 4 <= n) {\n uint64_t w;\n memcpy(&w, in + i, 8);\n if ((w & 0xFF80FF80FF80FF80ULL) == 0) {\n out[o + 0] = (uint8_t)(w);\n out[o + 1] = (uint8_t)(w >> 16);\n out[o + 2] = (uint8_t)(w >> 32);\n out[o + 3] = (uint8_t)(w >> 48);\n o += 4;\n i += 4;\n continue;\n }\n }\n uint32_t c = in[i];\n if (c < 0x80) {\n out[o++] = (uint8_t)c;\n i++;\n } else if (c < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (c >> 6));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xD800 || c >= 0xE000) {\n out[o++] = (uint8_t)(0xE0 | (c >> 12));\n out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (c & 0x3F));\n i++;\n } else if (c < 0xDC00) {\n if (i + 1 >= n) return INVALID;\n uint32_t lo = in[i + 1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n i += 2;\n } else {\n return INVALID;\n }\n }\n return o;\n}\nEOF\ncc -O2 -std=c17 -fno-lto -g -I /tmp -c /tmp/solve_v1.c -o /tmp/solve_v1.o\ncc -O2 -std=c17 -fno-lto -g /tmp/solve_v1.c verify/runner.c -o /tmp/runner_v1 -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v1) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgv1_$f.out /tmp/runner_v1 /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgv1_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v1) ==
5500068
== latin (v1) ==
16806060
== cjk (v1) ==
32041663
== emoji (v1) ==
20554528
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cp /tmp/solve_v1.c submission/solve.c && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.5s
verify 2.0s PASS
measure 0.5s 80,229,466 instructions (given: 78,181,481)
SCORE -0.0373 (0.974x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && python3 -c \"\nimport struct\nwith open('.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\ntotal=0\ncounts=[]\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n total+=cnt\n counts.append(cnt)\nprint('records',len(counts),'total units',total)\n\"\n"}
tool result
records 592 total units 1006084
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_real.out /tmp/runner_cur .build/corpus_1.bin >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_real.out | awk '{s+=$2} END{print s}'"}
tool result
80229466
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/iterate.sh << 'SCRIPT'\n#!/bin/bash\nset -e\ncd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\ncc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm 2>&1\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_real.out /tmp/runner_cur .build/corpus_1.bin >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_real.out | awk '{s+=$2} END{print s}'\nSCRIPT\nchmod +x /tmp/iterate.sh\n/tmp/iterate.sh"}
tool result
80229466
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/solve_v2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n *op++ = (uint8_t)c;\n ip++;\n } else if (c < 0x800) {\n op[0] = (uint8_t)(0xC0 | (c >> 6));\n op[1] = (uint8_t)(0x80 | (c & 0x3F));\n op += 2;\n ip++;\n } else if (c < 0xD800 || c >= 0xE000) {\n op[0] = (uint8_t)(0xE0 | (c >> 12));\n op[1] = (uint8_t)(0x80 | ((c >> 6) & 0x3F));\n op[2] = (uint8_t)(0x80 | (c & 0x3F));\n op += 3;\n ip++;\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n op[0] = (uint8_t)(0xF0 | (cp >> 18));\n op[1] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n op[2] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n op[3] = (uint8_t)(0x80 | (cp & 0x3F));\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\nEOF\ncp /tmp/solve_v2.c submission/solve.c\n/tmp/iterate.sh"}
tool result
71585065
--- Command finished with exit code: 0 ---
assistant
Better than given already. Let's run grade and continue optimizing.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.5s
verify 2.0s PASS
measure 0.5s 71,532,664 instructions (given: 78,181,481)
SCORE +0.1282 (1.093x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v2) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg2_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg2_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v2) ==
9000047
== latin (v2) ==
12791142
== cjk (v2) ==
23713647
== emoji (v2) ==
17650752
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "which callgrind_annotate"}
tool result
/usr/sbin/callgrind_annotate
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur | sed -n '/<utf16_to_utf8>:/,/^$/p' | head -80"}
tool result
0000000000001420 <utf16_to_utf8>:
1420: 48 89 f9 mov %rdi,%rcx
1423: 48 89 d7 mov %rdx,%rdi
1426: 4c 8d 04 71 lea (%rcx,%rsi,2),%r8
142a: 4c 39 c1 cmp %r8,%rcx
142d: 0f 83 1e 01 00 00 jae 1551 <utf16_to_utf8+0x131>
1433: 48 89 d0 mov %rdx,%rax
1436: eb 18 jmp 1450 <utf16_to_utf8+0x30>
1438: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
143f: 00
1440: 40 88 30 mov %sil,(%rax)
1443: 48 83 c1 02 add $0x2,%rcx
1447: 48 83 c0 01 add $0x1,%rax
144b: 4c 39 c1 cmp %r8,%rcx
144e: 73 33 jae 1483 <utf16_to_utf8+0x63>
1450: 0f b7 31 movzwl (%rcx),%esi
1453: 89 f2 mov %esi,%edx
1455: 66 83 fe 7f cmp $0x7f,%si
1459: 76 e5 jbe 1440 <utf16_to_utf8+0x20>
145b: 81 fe ff 07 00 00 cmp $0x7ff,%esi
1461: 77 2d ja 1490 <utf16_to_utf8+0x70>
1463: c1 ee 06 shr $0x6,%esi
1466: 83 e2 3f and $0x3f,%edx
1469: 48 83 c1 02 add $0x2,%rcx
146d: 48 83 c0 02 add $0x2,%rax
1471: 83 ce c0 or $0xffffffc0,%esi
1474: 83 ca 80 or $0xffffff80,%edx
1477: 40 88 70 fe mov %sil,-0x2(%rax)
147b: 88 50 ff mov %dl,-0x1(%rax)
147e: 4c 39 c1 cmp %r8,%rcx
1481: 72 cd jb 1450 <utf16_to_utf8+0x30>
1483: 48 29 f8 sub %rdi,%rax
1486: c3 ret
1487: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
148e: 00 00
1490: 44 8d 8e 00 28 ff ff lea -0xd800(%rsi),%r9d
1497: 41 81 f9 ff 07 00 00 cmp $0x7ff,%r9d
149e: 76 38 jbe 14d8 <utf16_to_utf8+0xb8>
14a0: 41 89 f1 mov %esi,%r9d
14a3: c1 ee 06 shr $0x6,%esi
14a6: 83 e2 3f and $0x3f,%edx
14a9: 48 83 c0 03 add $0x3,%rax
14ad: 41 c1 e9 0c shr $0xc,%r9d
14b1: 83 e6 3f and $0x3f,%esi
14b4: 83 ca 80 or $0xffffff80,%edx
14b7: 48 83 c1 02 add $0x2,%rcx
14bb: 41 83 c9 e0 or $0xffffffe0,%r9d
14bf: 83 ce 80 or $0xffffff80,%esi
14c2: 88 50 ff mov %dl,-0x1(%rax)
14c5: 44 88 48 fd mov %r9b,-0x3(%rax)
14c9: 40 88 70 fe mov %sil,-0x2(%rax)
14cd: e9 79 ff ff ff jmp 144b <utf16_to_utf8+0x2b>
14d2: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
14d8: 81 fe ff db 00 00 cmp $0xdbff,%esi
14de: 77 74 ja 1554 <utf16_to_utf8+0x134>
14e0: 48 8d 51 02 lea 0x2(%rcx),%rdx
14e4: 4c 39 c2 cmp %r8,%rdx
14e7: 73 6b jae 1554 <utf16_to_utf8+0x134>
14e9: 0f b7 51 02 movzwl 0x2(%rcx),%edx
14ed: 8d b2 00 24 ff ff lea -0xdc00(%rdx),%esi
14f3: 81 fe ff 03 00 00 cmp $0x3ff,%esi
14f9: 77 59 ja 1554 <utf16_to_utf8+0x134>
14fb: 41 c1 e1 0a shl $0xa,%r9d
14ff: 48 83 c0 04 add $0x4,%rax
1503: 48 83 c1 04 add $0x4,%rcx
1507: 41 01 d1 add %edx,%r9d
150a: 41 8d 91 00 24 00 00 lea 0x2400(%r9),%edx
1511: 41 c1 e9 06 shr $0x6,%r9d
1515: 89 d6 mov %edx,%esi
1517: 41 81 c1 90 00 00 00 add $0x90,%r9d
151e: c1 ee 12 shr $0x12,%esi
1521: 41 83 e1 3f and $0x3f,%r9d
1525: 83 ce f0 or $0xfffffff0,%esi
1528: 41 83 c9 80 or $0xffffff80,%r9d
152c: 40 88 70 fc mov %sil,-0x4(%rax)
1530: 89 d6 mov %edx,%esi
1532: 83 e2 3f and $0x3f,%edx
1535: c1 ee 0c shr $0xc,%esi
1538: 83 ca 80 or $0xffffff80,%edx
153b: 44 88 48 fe mov %r9b,-0x2(%rax)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/corpus_ascii.bin','rb') as f:\n data=f.read()\ncnt=struct.unpack('<I', data[:4])[0]\nunits=struct.unpack(f'<{cnt}H', data[4:4+2*cnt])\nprint(cnt, max(units), min(units))\nprint(units[:50])\n\""}
tool result
200000 126 32
(104, 40, 64, 47, 95, 89, 92, 115, 80, 58, 44, 94, 35, 81, 87, 109, 32, 121, 89, 66, 124, 61, 107, 45, 72, 35, 34, 35, 101, 33, 80, 119, 59, 86, 124, 35, 99, 60, 88, 95, 102, 61, 76, 61, 118, 60, 90, 69, 34, 85)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/solve_v3.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n *op++ = (uint8_t)c;\n ip++;\n } else if (c < 0x800) {\n uint32_t v = 0x0000C080u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } else if (c < 0xD800 || c >= 0xE000) {\n uint32_t v = 0x00E08080u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);\n memcpy(op, &v, 4);\n op += 3;\n ip++;\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0xF0808080u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\nEOF\ncp /tmp/solve_v3.c submission/solve.c\n/tmp/iterate.sh"}
tool result
70392280
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
MISMATCH (single) on 1 units: 0080
grade: FAIL (verification)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && python3 -c \"\nc=0x0080\nbyte0 = 0xC0 | (c>>6)\nbyte1 = 0x80 | (c & 0x3F)\nprint(hex(byte0), hex(byte1))\nv = byte0 | (byte1<<8)\nprint(hex(v))\n\""}
tool result
0xc2 0x80
0x80c2
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && python3 -c \"\nc=0x0080\nbyte0 = 0xC0 | (c>>6)\nbyte1 = 0x80 | (c & 0x3F)\nv = byte0 | (byte1<<8)\nprint(hex(v))\n# formula check\nv2 = 0x80C0 | (c>>6) | ((c&0x3F)<<8)\nprint(hex(v2))\n\""}
tool result
0x80c2
0x80c2
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "old_string": " uint32_t v = 0x0000C080u | ((c & 0x3F) << 8) | (c >> 6);", "new_string": " uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
17- uint32_t v = 0x0000C080u | ((c & 0x3F) << 8) | (c >> 6);
17+ uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
Context after edit (lines 14-20):
14│ *op++ = (uint8_t)c;
15│ ip++;
16│ } else if (c < 0x800) {
17│ uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
18│ memcpy(op, &v, 2);
19│ op += 2;
20│ ip++;
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " uint32_t v = 0x00808080u | 0x00000060u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);", "old_string": " uint32_t v = 0x00E08080u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
22- uint32_t v = 0x00E08080u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
22+ uint32_t v = 0x00808080u | 0x00000060u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
Context after edit (lines 19-25):
19│ op += 2;
20│ ip++;
21│ } else if (c < 0xD800 || c >= 0xE000) {
22│ uint32_t v = 0x00808080u | 0x00000060u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
23│ memcpy(op, &v, 4);
24│ op += 3;
25│ ip++;
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);", "old_string": " uint32_t v = 0x00808080u | 0x00000060u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
22- uint32_t v = 0x00808080u | 0x00000060u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
22+ uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
Context after edit (lines 19-25):
19│ op += 2;
20│ ip++;
21│ } else if (c < 0xD800 || c >= 0xE000) {
22│ uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
23│ memcpy(op, &v, 4);
24│ op += 3;
25│ ip++;
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);", "old_string": " uint32_t v = 0xF0808080u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
31- uint32_t v = 0xF0808080u
31+ uint32_t v = 0x808080F0u
Context after edit (lines 28-38):
28│ uint32_t lo = ip[1];
29│ if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
30│ uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
31│ uint32_t v = 0x808080F0u
32│ | ((cp & 0x3F) << 24)
33│ | (((cp >> 6) & 0x3F) << 16)
34│ | (((cp >> 12) & 0x3F) << 8)
35│ | (cp >> 18);
36│ memcpy(op, &v, 4);
37│ op += 4;
38│ ip += 2;
tool call: bash
{"command": "python3 -c \"\nimport random\ndef ref(c):\n if c<0x800:\n b0=0xC0|(c>>6); b1=0x80|(c&0x3F)\n return bytes([b0,b1])\ndef ref3(c):\n b0=0xE0|(c>>12); b1=0x80|((c>>6)&0x3F); b2=0x80|(c&0x3F)\n return bytes([b0,b1,b2])\ndef ref4(cp):\n b0=0xF0|(cp>>18); b1=0x80|((cp>>12)&0x3F); b2=0x80|((cp>>6)&0x3F); b3=0x80|(cp&0x3F)\n return bytes([b0,b1,b2,b3])\n\ndef mine2(c):\n v = 0x000080C0 | ((c&0x3F)<<8) | (c>>6)\n return v.to_bytes(4,'little')[:2]\n\ndef mine3(c):\n v = 0x008080E0 | ((c&0x3F)<<16) | (((c>>6)&0x3F)<<8) | (c>>12)\n return v.to_bytes(4,'little')[:3]\n\ndef mine4(cp):\n v = 0x808080F0 | ((cp&0x3F)<<24) | (((cp>>6)&0x3F)<<16) | (((cp>>12)&0x3F)<<8) | (cp>>18)\n return v.to_bytes(4,'little')\n\nbad=0\nfor c in range(0x80,0x800):\n if ref(c)!=mine2(c): bad+=1; print('2byte bad',hex(c))\nfor c in list(range(0x800,0xD800))+list(range(0xE000,0x10000)):\n if ref3(c)!=mine3(c): bad+=1; print('3byte bad',hex(c))\nfor _ in range(200000):\n cp=random.randrange(0x10000,0x110000)\n if ref4(cp)!=mine4(cp): bad+=1; print('4byte bad',hex(cp))\nprint('bad',bad)\n\"\n"}
tool result
bad 0
--- Command finished with exit code: 0 ---
assistant
Formulas check out. Now let's test.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
70392280
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.5s
verify 2.0s PASS
measure 0.6s 70,339,879 instructions (given: 78,181,481)
SCORE +0.1525 (1.111x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v3) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg3_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg3_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v3) ==
9000047
== latin (v3) ==
12791142
== cjk (v3) ==
22794047
== emoji (v3) ==
17304722
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '1,60p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_real.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 2984685
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 1263, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
14,067,739 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
14,067,739 (100.0%) submission/solve.c:utf16_to_utf8 [/tmp/runner_cur]
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
. #include <stdint.h>
. #include <stddef.h>
. #include <string.h>
.
. #define INVALID ((size_t)-1)
.
1,184 ( 0.01%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
1,184 ( 0.01%) uint8_t *op = out;
. const uint16_t *ip = in;
592 ( 0.00%) const uint16_t *end = in + n;
1,908,550 (13.57%) while (ip < end) {
1,907,366 (13.56%) uint32_t c = *ip;
1,907,366 (13.56%) if (c < 0x80) {
1,156,626 ( 8.22%) *op++ = (uint8_t)c;
578,313 ( 4.11%) ip++;
750,740 ( 5.34%) } else if (c < 0x800) {
684,065 ( 4.86%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
136,813 ( 0.97%) memcpy(op, &v, 2);
136,813 ( 0.97%) op += 2;
136,813 ( 0.97%) ip++;
715,671 ( 5.09%) } else if (c < 0xD800 || c >= 0xE000) {
1,861,560 (13.23%) uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
. memcpy(op, &v, 4);
186,156 ( 1.32%) op += 3;
372,312 ( 2.65%) ip++;
104,802 ( 0.74%) } else if (c < 0xDC00) {
157,203 ( 1.12%) if (ip + 1 >= end) return INVALID;
52,401 ( 0.37%) uint32_t lo = ip[1];
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#define INVALID ((size_t)-1)
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
*op++ = (uint8_t)c;
ip++;
} else if (c < 0x800) {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} else if (c < 0xD800 || c >= 0xE000) {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_real.out | awk '{s+=$2} END{print s}'\necho ---\nwc -l /tmp/cg_real.out\ntail -30 /tmp/cg_real.out"}
tool result
70392280
---
117 /tmp/cg_real.out
+2 52401
-2 52401
+2 209604
+3 52401
fl=(209)
fn=(724)
cfi=(241)
cfn=(912)
calls=592 7
30 14067739
ob=(2)
fl=(203)
fn=(696)
cfi=(205)
cfn=(716)
calls=1 30
360 14067739
ob=(1) /usr/lib/ld-linux-x86-64.so.2
fl=(1) ???
fn=(0) 0x000000000001f100
cob=(6)
cfi=(202)
cfn=(694)
calls=1 0
0 14067739
totals: 14067739
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "head -60 /tmp/cg_real.out"}
tool result
# callgrind format
version: 1
creator: callgrind-3.25.1
pid: 1263
cmd: /tmp/runner_cur .build/corpus_1.bin
part: 1
desc: I1 cache:
desc: D1 cache:
desc: LL cache:
desc: Timerange: Basic block 0 - 2984685
desc: Trigger: Program termination
positions: line
events: Ir
summary: 14067739
ob=(6) /tmp/runner_cur
fl=(202) ???
fn=(694) (below main)
cob=(2) /usr/lib/libc.so.6
cfi=(203) /usr/src/debug/glibc/glibc/csu/../csu/libc-start.c
cfn=(696) __libc_start_main@@GLIBC_2.34
calls=1 242
0 14067739
fl=(241) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c
fn=(912) utf16_to_utf8
7 1184
+3 592
+1 1184
-3 1184
+6 578313
+1 578313
-1 578313
-3 1633740
+1 1907366
+1 1907366
+3 750740
+1 273626
+3 136813
-1 136813
-2 410439
+1 136813
-7 273626
+32 1184
-22 715671
+1 558468
+2 186156
-2 558468
+3 186156
-3 744624
+3 186156
+1 104802
+1 157203
+1 52401
+1 157203
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "/tmp/iterate.sh\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_real.out | awk '{s+=$2} END{print s}'\ncallgrind_annotate /tmp/cg_real.out 2>/dev/null | grep \"PROGRAM TOTALS\""}
tool result
70392280
70392280
14,067,739 (100.0%) PROGRAM TOTALS
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\nlens=[]\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4+2*cnt\n lens.append(cnt)\nimport statistics\nprint(len(lens), min(lens), max(lens), statistics.mean(lens))\n\""}
tool result
592 502 2998 1699.4662162162163
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '1,50p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_real.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 2984686
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 1442, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
14,067,739 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
14,067,739 (100.0%) submission/solve.c:utf16_to_utf8 [/tmp/runner_cur]
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
. #include <stdint.h>
. #include <stddef.h>
. #include <string.h>
.
. #define INVALID ((size_t)-1)
.
1,184 ( 0.01%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
1,184 ( 0.01%) uint8_t *op = out;
. const uint16_t *ip = in;
592 ( 0.00%) const uint16_t *end = in + n;
1,908,550 (13.57%) while (ip < end) {
1,907,366 (13.56%) uint32_t c = *ip;
1,907,366 (13.56%) if (c < 0x80) {
1,156,626 ( 8.22%) *op++ = (uint8_t)c;
578,313 ( 4.11%) ip++;
750,740 ( 5.34%) } else if (c < 0x800) {
684,065 ( 4.86%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
136,813 ( 0.97%) memcpy(op, &v, 2);
--- Command finished with exit code: 0 ---
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n *op++ = (uint8_t)c;\n ip++;\n } else if (c < 0x800) {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } else if ((c & 0xF800) != 0xD800) {\n uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);\n memcpy(op, &v, 4);\n op += 3;\n ip++;\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (44 lines):
21- } else if (c < 0xD800 || c >= 0xE000) {
21+ } else if ((c & 0xF800) != 0xD800) {
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
70598332
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "old_string": " } else if ((c & 0xF800) != 0xD800) {", "new_string": " } else if (c < 0xD800 || c >= 0xE000) {"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
21- } else if ((c & 0xF800) != 0xD800) {
21+ } else if (c < 0xD800 || c >= 0xE000) {
Context after edit (lines 18-24):
18│ memcpy(op, &v, 2);
19│ op += 2;
20│ ip++;
21│ } else if (c < 0xD800 || c >= 0xE000) {
22│ uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
23│ memcpy(op, &v, 4);
24│ op += 3;
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\ncnt1=cnt2=cnt3=cnt4=0\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c=units[i]\n if c<0x80: cnt1+=1; i+=1\n elif c<0x800: cnt2+=1; i+=1\n elif c<0xD800 or c>=0xE000: cnt3+=1; i+=1\n else: cnt4+=1; i+=2\nprint('1byte',cnt1,'2byte',cnt2,'3byte',cnt3,'pairs',cnt4)\ntotal=cnt1+cnt2+cnt3+cnt4\nprint('fractions', cnt1/total, cnt2/total, cnt3/total, cnt4/total)\n\"\n"}
tool result
1byte 578313 2byte 136813 3byte 186156 pairs 52401
fractions 0.6063996107721329 0.14345752204873108 0.19519693650825273 0.054945930670883304
--- Command finished with exit code: 0 ---
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n *op++ = (uint8_t)c;\n ip++;\n } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);\n memcpy(op, &v, 4);\n op += 3;\n ip++;\n } else if (c < 0x800) {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (44 lines):
16+ } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
17+ uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
18+ memcpy(op, &v, 4);
19+ op += 3;
20+ ip++;
20- ip++;
21- } else if (c < 0xD800 || c >= 0xE000) {
22- uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
23- memcpy(op, &v, 4);
24- op += 3;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
67746404
--- Command finished with exit code: 0 ---
assistant
Nice, improvement. Let's verify correctness and grade.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.5s
verify 2.0s PASS
measure 0.5s 67,216,889 instructions (given: 78,181,481)
SCORE +0.2180 (1.163x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v4) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg4_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg4_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v4) ==
8000047
== latin (v4) ==
13415897
== cjk (v4) ==
20874447
== emoji (v4) ==
17342817
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '28,70p'"}
tool result
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
. #include <stdint.h>
. #include <stddef.h>
. #include <string.h>
.
. #define INVALID ((size_t)-1)
.
1,184 ( 0.01%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
1,184 ( 0.01%) uint8_t *op = out;
. const uint16_t *ip = in;
592 ( 0.00%) const uint16_t *end = in + n;
1,908,550 (14.20%) while (ip < end) {
953,683 ( 7.09%) uint32_t c = *ip;
1,907,366 (14.19%) if (c < 0x80) {
1,156,626 ( 8.60%) *op++ = (uint8_t)c;
578,313 ( 4.30%) ip++;
1,603,224 (11.93%) } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
1,861,560 (13.85%) uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
. memcpy(op, &v, 4);
186,156 ( 1.38%) op += 3;
186,156 ( 1.38%) ip++;
104,802 ( 0.78%) } else if (c < 0x800) {
820,878 ( 6.11%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
136,813 ( 1.02%) memcpy(op, &v, 2);
136,813 ( 1.02%) op += 2;
273,626 ( 2.04%) ip++;
104,802 ( 0.78%) } else if (c < 0xDC00) {
157,203 ( 1.17%) if (ip + 1 >= end) return INVALID;
52,401 ( 0.39%) uint32_t lo = ip[1];
157,203 ( 1.17%) if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
157,203 ( 1.17%) uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
. uint32_t v = 0x808080F0u
104,802 ( 0.78%) | ((cp & 0x3F) << 24)
209,604 ( 1.56%) | (((cp >> 6) & 0x3F) << 16)
157,203 ( 1.17%) | (((cp >> 12) & 0x3F) << 8)
366,807 ( 2.73%) | (cp >> 18);
. memcpy(op, &v, 4);
52,401 ( 0.39%) op += 4;
104,802 ( 0.78%) ip += 2;
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#define INVALID ((size_t)-1)
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
*op++ = (uint8_t)c;
ip++;
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} else if (c < 0x800) {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n do {\n *op++ = (uint8_t)c;\n ip++;\n } while (ip < end && (c = *ip) < 0x80);\n } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n do {\n uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);\n memcpy(op, &v, 4);\n op += 3;\n ip++;\n } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));\n } else if (c < 0x800) {\n do {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (50 lines):
14- *op++ = (uint8_t)c;
15- ip++;
14+ do {
15+ *op++ = (uint8_t)c;
16+ ip++;
17+ } while (ip < end && (c = *ip) < 0x80);
17- uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
18- memcpy(op, &v, 4);
19- op += 3;
20- ip++;
19+ do {
20+ uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
21+ memcpy(op, &v, 4);
22+ op += 3;
23+ ip++;
24+ } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
22- uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
23- memcpy(op, &v, 2);
24- op += 2;
25- ip++;
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
64465774
--- Command finished with exit code: 0 ---
assistant
Improvement! Let's grade.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.5s
verify 2.0s PASS
measure 0.5s 64,465,774 instructions (given: 78,181,481)
SCORE +0.2783 (1.213x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v5) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg5_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg5_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v5) ==
8000047
== latin (v5) ==
12708887
== cjk (v5) ==
19196817
== emoji (v5) ==
17135387
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur | sed -n '/<utf16_to_utf8>:/,/ret/p' | head -40"}
tool result
0000000000001440 <utf16_to_utf8>:
1440: 48 89 f9 mov %rdi,%rcx
1443: 48 89 d7 mov %rdx,%rdi
1446: 4c 8d 04 71 lea (%rcx,%rsi,2),%r8
144a: 4c 39 c1 cmp %r8,%rcx
144d: 0f 83 ab 01 00 00 jae 15fe <utf16_to_utf8+0x1be>
1453: 48 89 d0 mov %rdx,%rax
1456: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
145d: 00 00 00
1460: 0f b7 11 movzwl (%rcx),%edx
1463: 83 fa 7f cmp $0x7f,%edx
1466: 0f 86 e0 00 00 00 jbe 154c <utf16_to_utf8+0x10c>
146c: 8d b2 00 28 ff ff lea -0xd800(%rdx),%esi
1472: 81 fa ff 07 00 00 cmp $0x7ff,%edx
1478: 0f 86 55 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
147e: 81 fe ff 07 00 00 cmp $0x7ff,%esi
1484: 0f 87 f7 00 00 00 ja 1581 <utf16_to_utf8+0x141>
148a: 81 fa ff 07 00 00 cmp $0x7ff,%edx
1490: 0f 86 3d 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
1496: 81 fa ff db 00 00 cmp $0xdbff,%edx
149c: 0f 87 66 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14a2: 48 8d 51 02 lea 0x2(%rcx),%rdx
14a6: 4c 39 c2 cmp %r8,%rdx
14a9: 0f 83 59 01 00 00 jae 1608 <utf16_to_utf8+0x1c8>
14af: 0f b7 51 02 movzwl 0x2(%rcx),%edx
14b3: 44 8d 8a 00 24 ff ff lea -0xdc00(%rdx),%r9d
14ba: 41 81 f9 ff 03 00 00 cmp $0x3ff,%r9d
14c1: 0f 87 41 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14c7: c1 e6 0a shl $0xa,%esi
14ca: 48 83 c1 04 add $0x4,%rcx
14ce: 48 83 c0 04 add $0x4,%rax
14d2: 01 f2 add %esi,%edx
14d4: 44 8d 8a 00 24 00 00 lea 0x2400(%rdx),%r9d
14db: c1 ea 06 shr $0x6,%edx
14de: 44 89 ce mov %r9d,%esi
14e1: 45 89 ca mov %r9d,%r10d
14e4: 81 c2 90 00 00 00 add $0x90,%edx
14ea: 41 c1 e1 18 shl $0x18,%r9d
14ee: c1 ee 04 shr $0x4,%esi
14f1: 41 c1 ea 12 shr $0x12,%r10d
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur | sed -n '/<utf16_to_utf8>:/,/^0000/p' | head -160"}
tool result
0000000000001440 <utf16_to_utf8>:
1440: 48 89 f9 mov %rdi,%rcx
1443: 48 89 d7 mov %rdx,%rdi
1446: 4c 8d 04 71 lea (%rcx,%rsi,2),%r8
144a: 4c 39 c1 cmp %r8,%rcx
144d: 0f 83 ab 01 00 00 jae 15fe <utf16_to_utf8+0x1be>
1453: 48 89 d0 mov %rdx,%rax
1456: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
145d: 00 00 00
1460: 0f b7 11 movzwl (%rcx),%edx
1463: 83 fa 7f cmp $0x7f,%edx
1466: 0f 86 e0 00 00 00 jbe 154c <utf16_to_utf8+0x10c>
146c: 8d b2 00 28 ff ff lea -0xd800(%rdx),%esi
1472: 81 fa ff 07 00 00 cmp $0x7ff,%edx
1478: 0f 86 55 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
147e: 81 fe ff 07 00 00 cmp $0x7ff,%esi
1484: 0f 87 f7 00 00 00 ja 1581 <utf16_to_utf8+0x141>
148a: 81 fa ff 07 00 00 cmp $0x7ff,%edx
1490: 0f 86 3d 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
1496: 81 fa ff db 00 00 cmp $0xdbff,%edx
149c: 0f 87 66 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14a2: 48 8d 51 02 lea 0x2(%rcx),%rdx
14a6: 4c 39 c2 cmp %r8,%rdx
14a9: 0f 83 59 01 00 00 jae 1608 <utf16_to_utf8+0x1c8>
14af: 0f b7 51 02 movzwl 0x2(%rcx),%edx
14b3: 44 8d 8a 00 24 ff ff lea -0xdc00(%rdx),%r9d
14ba: 41 81 f9 ff 03 00 00 cmp $0x3ff,%r9d
14c1: 0f 87 41 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14c7: c1 e6 0a shl $0xa,%esi
14ca: 48 83 c1 04 add $0x4,%rcx
14ce: 48 83 c0 04 add $0x4,%rax
14d2: 01 f2 add %esi,%edx
14d4: 44 8d 8a 00 24 00 00 lea 0x2400(%rdx),%r9d
14db: c1 ea 06 shr $0x6,%edx
14de: 44 89 ce mov %r9d,%esi
14e1: 45 89 ca mov %r9d,%r10d
14e4: 81 c2 90 00 00 00 add $0x90,%edx
14ea: 41 c1 e1 18 shl $0x18,%r9d
14ee: c1 ee 04 shr $0x4,%esi
14f1: 41 c1 ea 12 shr $0x12,%r10d
14f5: 41 81 e1 00 00 00 3f and $0x3f000000,%r9d
14fc: 81 e6 00 3f 00 00 and $0x3f00,%esi
1502: c1 e2 10 shl $0x10,%edx
1505: 44 09 d6 or %r10d,%esi
1508: 81 e2 00 00 3f 00 and $0x3f0000,%edx
150e: 44 09 ce or %r9d,%esi
1511: 09 f2 or %esi,%edx
1513: 81 ca f0 80 80 80 or $0x808080f0,%edx
1519: 89 50 fc mov %edx,-0x4(%rax)
151c: 4c 39 c1 cmp %r8,%rcx
151f: 0f 82 3b ff ff ff jb 1460 <utf16_to_utf8+0x20>
1525: 48 29 f8 sub %rdi,%rax
1528: c3 ret
1529: 90 nop
152a: 66 66 2e 0f 1f 84 00 data16 cs nopw 0x0(%rax,%rax,1)
1531: 00 00 00 00
1535: 66 66 2e 0f 1f 84 00 data16 cs nopw 0x0(%rax,%rax,1)
153c: 00 00 00 00
1540: 0f b7 11 movzwl (%rcx),%edx
1543: 83 fa 7f cmp $0x7f,%edx
1546: 0f 87 14 ff ff ff ja 1460 <utf16_to_utf8+0x20>
154c: 48 83 c1 02 add $0x2,%rcx
1550: 48 83 c0 01 add $0x1,%rax
1554: 88 50 ff mov %dl,-0x1(%rax)
1557: 4c 39 c1 cmp %r8,%rcx
155a: 72 e4 jb 1540 <utf16_to_utf8+0x100>
155c: 48 29 f8 sub %rdi,%rax
155f: c3 ret
1560: 0f b7 11 movzwl (%rcx),%edx
1563: 81 fa ff 07 00 00 cmp $0x7ff,%edx
1569: 0f 86 f1 fe ff ff jbe 1460 <utf16_to_utf8+0x20>
156f: 8d b2 00 28 ff ff lea -0xd800(%rdx),%esi
1575: 81 fe ff 07 00 00 cmp $0x7ff,%esi
157b: 0f 86 df fe ff ff jbe 1460 <utf16_to_utf8+0x20>
1581: 8d 34 95 00 00 00 00 lea 0x0(,%rdx,4),%esi
1588: 41 89 d1 mov %edx,%r9d
158b: c1 e2 10 shl $0x10,%edx
158e: 48 83 c1 02 add $0x2,%rcx
1592: 81 e6 00 3f 00 00 and $0x3f00,%esi
1598: 41 c1 e9 0c shr $0xc,%r9d
159c: 81 e2 00 00 3f 00 and $0x3f0000,%edx
15a2: 48 83 c0 03 add $0x3,%rax
15a6: 44 09 ce or %r9d,%esi
15a9: 09 f2 or %esi,%edx
15ab: 81 ca e0 80 80 00 or $0x8080e0,%edx
15b1: 89 50 fd mov %edx,-0x3(%rax)
15b4: 4c 39 c1 cmp %r8,%rcx
15b7: 72 a7 jb 1560 <utf16_to_utf8+0x120>
15b9: 48 29 f8 sub %rdi,%rax
15bc: c3 ret
15bd: 0f 1f 00 nopl (%rax)
15c0: 0f b7 11 movzwl (%rcx),%edx
15c3: 89 d6 mov %edx,%esi
15c5: 83 c6 80 add $0xffffff80,%esi
15c8: 66 81 fe 7f 07 cmp $0x77f,%si
15cd: 0f 87 8d fe ff ff ja 1460 <utf16_to_utf8+0x20>
15d3: 89 d6 mov %edx,%esi
15d5: c1 ea 06 shr $0x6,%edx
15d8: 48 83 c1 02 add $0x2,%rcx
15dc: 48 83 c0 02 add $0x2,%rax
15e0: c1 e6 08 shl $0x8,%esi
15e3: 81 e6 00 3f 00 00 and $0x3f00,%esi
15e9: 09 f2 or %esi,%edx
15eb: 81 ca c0 80 00 00 or $0x80c0,%edx
15f1: 66 89 50 fe mov %dx,-0x2(%rax)
15f5: 4c 39 c1 cmp %r8,%rcx
15f8: 72 c6 jb 15c0 <utf16_to_utf8+0x180>
15fa: 48 29 f8 sub %rdi,%rax
15fd: c3 ret
15fe: 31 c0 xor %eax,%eax
1600: c3 ret
1601: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
1608: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
160f: c3 ret
Disassembly of section .fini:
0000000000001610 <_fini>:
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '28,75p'"}
tool result
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
. #include <stdint.h>
. #include <stddef.h>
. #include <string.h>
.
. #define INVALID ((size_t)-1)
.
1,184 ( 0.01%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
1,184 ( 0.01%) uint8_t *op = out;
. const uint16_t *ip = in;
592 ( 0.00%) const uint16_t *end = in + n;
105,986 ( 0.82%) while (ip < end) {
89,027 ( 0.69%) uint32_t c = *ip;
178,054 ( 1.38%) if (c < 0x80) {
. do {
1,156,626 ( 8.97%) *op++ = (uint8_t)c;
578,313 ( 4.49%) ip++;
2,890,605 (22.42%) } while (ip < end && (c = *ip) < 0x80);
314,491 ( 2.44%) } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
. do {
1,861,560 (14.44%) uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
. memcpy(op, &v, 4);
186,156 ( 1.44%) op += 3;
186,156 ( 1.44%) ip++;
1,476,405 (11.45%) } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
104,802 ( 0.81%) } else if (c < 0x800) {
. do {
820,878 ( 6.37%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
136,813 ( 1.06%) memcpy(op, &v, 2);
136,813 ( 1.06%) op += 2;
136,813 ( 1.06%) ip++;
957,246 ( 7.42%) } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
104,802 ( 0.81%) } else if (c < 0xDC00) {
157,203 ( 1.22%) if (ip + 1 >= end) return INVALID;
52,401 ( 0.41%) uint32_t lo = ip[1];
157,203 ( 1.22%) if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
157,203 ( 1.22%) uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
. uint32_t v = 0x808080F0u
104,802 ( 0.81%) | ((cp & 0x3F) << 24)
209,604 ( 1.63%) | (((cp >> 6) & 0x3F) << 16)
157,203 ( 1.22%) | (((cp >> 12) & 0x3F) << 8)
366,807 ( 2.85%) | (cp >> 18);
. memcpy(op, &v, 4);
52,401 ( 0.41%) op += 4;
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#define INVALID ((size_t)-1)
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
} else if (c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/sse2test.c << 'EOF'\n#include <emmintrin.h>\n#include <stdint.h>\n#include <stdio.h>\nint main(void) {\n uint16_t buf[8] = {1,2,3,4,5,6,7,8};\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n __m128i z = _mm_setzero_si128();\n __m128i packed = _mm_packus_epi16(v, z);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, packed);\n printf(\"%d %d\\n\", out[0], out[7]);\n return 0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/sse2test /tmp/sse2test.c && /tmp/sse2test"}
tool result
1 8
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | sed -n '/<utf16_to_utf8>:/,/^0000/p'"}
tool result
0000000000001440 <utf16_to_utf8>:
1440: 48 89 f9 mov rcx,rdi
1443: 48 89 d7 mov rdi,rdx
1446: 4c 8d 04 71 lea r8,[rcx+rsi*2]
144a: 4c 39 c1 cmp rcx,r8
144d: 0f 83 ab 01 00 00 jae 15fe <utf16_to_utf8+0x1be>
1453: 48 89 d0 mov rax,rdx
1456: 66 2e 0f 1f 84 00 00 cs nop WORD PTR [rax+rax*1+0x0]
145d: 00 00 00
1460: 0f b7 11 movzx edx,WORD PTR [rcx]
1463: 83 fa 7f cmp edx,0x7f
1466: 0f 86 e0 00 00 00 jbe 154c <utf16_to_utf8+0x10c>
146c: 8d b2 00 28 ff ff lea esi,[rdx-0xd800]
1472: 81 fa ff 07 00 00 cmp edx,0x7ff
1478: 0f 86 55 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
147e: 81 fe ff 07 00 00 cmp esi,0x7ff
1484: 0f 87 f7 00 00 00 ja 1581 <utf16_to_utf8+0x141>
148a: 81 fa ff 07 00 00 cmp edx,0x7ff
1490: 0f 86 3d 01 00 00 jbe 15d3 <utf16_to_utf8+0x193>
1496: 81 fa ff db 00 00 cmp edx,0xdbff
149c: 0f 87 66 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14a2: 48 8d 51 02 lea rdx,[rcx+0x2]
14a6: 4c 39 c2 cmp rdx,r8
14a9: 0f 83 59 01 00 00 jae 1608 <utf16_to_utf8+0x1c8>
14af: 0f b7 51 02 movzx edx,WORD PTR [rcx+0x2]
14b3: 44 8d 8a 00 24 ff ff lea r9d,[rdx-0xdc00]
14ba: 41 81 f9 ff 03 00 00 cmp r9d,0x3ff
14c1: 0f 87 41 01 00 00 ja 1608 <utf16_to_utf8+0x1c8>
14c7: c1 e6 0a shl esi,0xa
14ca: 48 83 c1 04 add rcx,0x4
14ce: 48 83 c0 04 add rax,0x4
14d2: 01 f2 add edx,esi
14d4: 44 8d 8a 00 24 00 00 lea r9d,[rdx+0x2400]
14db: c1 ea 06 shr edx,0x6
14de: 44 89 ce mov esi,r9d
14e1: 45 89 ca mov r10d,r9d
14e4: 81 c2 90 00 00 00 add edx,0x90
14ea: 41 c1 e1 18 shl r9d,0x18
14ee: c1 ee 04 shr esi,0x4
14f1: 41 c1 ea 12 shr r10d,0x12
14f5: 41 81 e1 00 00 00 3f and r9d,0x3f000000
14fc: 81 e6 00 3f 00 00 and esi,0x3f00
1502: c1 e2 10 shl edx,0x10
1505: 44 09 d6 or esi,r10d
1508: 81 e2 00 00 3f 00 and edx,0x3f0000
150e: 44 09 ce or esi,r9d
1511: 09 f2 or edx,esi
1513: 81 ca f0 80 80 80 or edx,0x808080f0
1519: 89 50 fc mov DWORD PTR [rax-0x4],edx
151c: 4c 39 c1 cmp rcx,r8
151f: 0f 82 3b ff ff ff jb 1460 <utf16_to_utf8+0x20>
1525: 48 29 f8 sub rax,rdi
1528: c3 ret
1529: 90 nop
152a: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
1531: 00 00 00 00
1535: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
153c: 00 00 00 00
1540: 0f b7 11 movzx edx,WORD PTR [rcx]
1543: 83 fa 7f cmp edx,0x7f
1546: 0f 87 14 ff ff ff ja 1460 <utf16_to_utf8+0x20>
154c: 48 83 c1 02 add rcx,0x2
1550: 48 83 c0 01 add rax,0x1
1554: 88 50 ff mov BYTE PTR [rax-0x1],dl
1557: 4c 39 c1 cmp rcx,r8
155a: 72 e4 jb 1540 <utf16_to_utf8+0x100>
155c: 48 29 f8 sub rax,rdi
155f: c3 ret
1560: 0f b7 11 movzx edx,WORD PTR [rcx]
1563: 81 fa ff 07 00 00 cmp edx,0x7ff
1569: 0f 86 f1 fe ff ff jbe 1460 <utf16_to_utf8+0x20>
156f: 8d b2 00 28 ff ff lea esi,[rdx-0xd800]
1575: 81 fe ff 07 00 00 cmp esi,0x7ff
157b: 0f 86 df fe ff ff jbe 1460 <utf16_to_utf8+0x20>
1581: 8d 34 95 00 00 00 00 lea esi,[rdx*4+0x0]
1588: 41 89 d1 mov r9d,edx
158b: c1 e2 10 shl edx,0x10
158e: 48 83 c1 02 add rcx,0x2
1592: 81 e6 00 3f 00 00 and esi,0x3f00
1598: 41 c1 e9 0c shr r9d,0xc
159c: 81 e2 00 00 3f 00 and edx,0x3f0000
15a2: 48 83 c0 03 add rax,0x3
15a6: 44 09 ce or esi,r9d
15a9: 09 f2 or edx,esi
15ab: 81 ca e0 80 80 00 or edx,0x8080e0
15b1: 89 50 fd mov DWORD PTR [rax-0x3],edx
15b4: 4c 39 c1 cmp rcx,r8
15b7: 72 a7 jb 1560 <utf16_to_utf8+0x120>
15b9: 48 29 f8 sub rax,rdi
15bc: c3 ret
15bd: 0f 1f 00 nop DWORD PTR [rax]
15c0: 0f b7 11 movzx edx,WORD PTR [rcx]
15c3: 89 d6 mov esi,edx
15c5: 83 c6 80 add esi,0xffffff80
15c8: 66 81 fe 7f 07 cmp si,0x77f
15cd: 0f 87 8d fe ff ff ja 1460 <utf16_to_utf8+0x20>
15d3: 89 d6 mov esi,edx
15d5: c1 ea 06 shr edx,0x6
15d8: 48 83 c1 02 add rcx,0x2
15dc: 48 83 c0 02 add rax,0x2
15e0: c1 e6 08 shl esi,0x8
15e3: 81 e6 00 3f 00 00 and esi,0x3f00
15e9: 09 f2 or edx,esi
15eb: 81 ca c0 80 00 00 or edx,0x80c0
15f1: 66 89 50 fe mov WORD PTR [rax-0x2],dx
15f5: 4c 39 c1 cmp rcx,r8
15f8: 72 c6 jb 15c0 <utf16_to_utf8+0x180>
15fa: 48 29 f8 sub rax,rdi
15fd: c3 ret
15fe: 31 c0 xor eax,eax
1600: c3 ret
1601: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0]
1608: 48 c7 c0 ff ff ff ff mov rax,0xffffffffffffffff
160f: c3 ret
Disassembly of section .fini:
0000000000001610 <_fini>:
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c > /tmp/solve_v5.c\ncp /tmp/solve_v5.c /tmp/solve_backup_v5.c\necho saved"}
tool result
saved
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat > /tmp/asciitest.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <stdlib.h>\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);\nint main(void) {\n size_t n = 200000;\n uint16_t *in = malloc(n*2);\n uint8_t *out = malloc(n*3+16);\n for (size_t i=0;i<n;i++) in[i] = 'A' + (i%26);\n size_t r = utf16_to_utf8(in, n, out);\n return (int)(r & 0xff);\n}\nEOF\ncc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c /tmp/asciitest.c -o /tmp/asciitest\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_asciimini.out /tmp/asciitest >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_asciimini.out | awk '{s+=$2} END{print s}'"}
tool result
8000047
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/asciitest --start-address=0x1440 --stop-address=0x1620 -M intel | head -80"}
tool result
/tmp/asciitest: file format elf64-x86-64
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/asciitest -M intel | sed -n '/<utf16_to_utf8>:/,/^0000/p'"}
tool result
00000000000011c0 <utf16_to_utf8>:
11c0: 48 89 f9 mov rcx,rdi
11c3: 48 89 d7 mov rdi,rdx
11c6: 4c 8d 04 71 lea r8,[rcx+rsi*2]
11ca: 4c 39 c1 cmp rcx,r8
11cd: 0f 83 ab 01 00 00 jae 137e <utf16_to_utf8+0x1be>
11d3: 48 89 d0 mov rax,rdx
11d6: 66 2e 0f 1f 84 00 00 cs nop WORD PTR [rax+rax*1+0x0]
11dd: 00 00 00
11e0: 0f b7 11 movzx edx,WORD PTR [rcx]
11e3: 83 fa 7f cmp edx,0x7f
11e6: 0f 86 e0 00 00 00 jbe 12cc <utf16_to_utf8+0x10c>
11ec: 8d b2 00 28 ff ff lea esi,[rdx-0xd800]
11f2: 81 fa ff 07 00 00 cmp edx,0x7ff
11f8: 0f 86 55 01 00 00 jbe 1353 <utf16_to_utf8+0x193>
11fe: 81 fe ff 07 00 00 cmp esi,0x7ff
1204: 0f 87 f7 00 00 00 ja 1301 <utf16_to_utf8+0x141>
120a: 81 fa ff 07 00 00 cmp edx,0x7ff
1210: 0f 86 3d 01 00 00 jbe 1353 <utf16_to_utf8+0x193>
1216: 81 fa ff db 00 00 cmp edx,0xdbff
121c: 0f 87 66 01 00 00 ja 1388 <utf16_to_utf8+0x1c8>
1222: 48 8d 51 02 lea rdx,[rcx+0x2]
1226: 4c 39 c2 cmp rdx,r8
1229: 0f 83 59 01 00 00 jae 1388 <utf16_to_utf8+0x1c8>
122f: 0f b7 51 02 movzx edx,WORD PTR [rcx+0x2]
1233: 44 8d 8a 00 24 ff ff lea r9d,[rdx-0xdc00]
123a: 41 81 f9 ff 03 00 00 cmp r9d,0x3ff
1241: 0f 87 41 01 00 00 ja 1388 <utf16_to_utf8+0x1c8>
1247: c1 e6 0a shl esi,0xa
124a: 48 83 c1 04 add rcx,0x4
124e: 48 83 c0 04 add rax,0x4
1252: 01 f2 add edx,esi
1254: 44 8d 8a 00 24 00 00 lea r9d,[rdx+0x2400]
125b: c1 ea 06 shr edx,0x6
125e: 44 89 ce mov esi,r9d
1261: 45 89 ca mov r10d,r9d
1264: 81 c2 90 00 00 00 add edx,0x90
126a: 41 c1 e1 18 shl r9d,0x18
126e: c1 ee 04 shr esi,0x4
1271: 41 c1 ea 12 shr r10d,0x12
1275: 41 81 e1 00 00 00 3f and r9d,0x3f000000
127c: 81 e6 00 3f 00 00 and esi,0x3f00
1282: c1 e2 10 shl edx,0x10
1285: 44 09 d6 or esi,r10d
1288: 81 e2 00 00 3f 00 and edx,0x3f0000
128e: 44 09 ce or esi,r9d
1291: 09 f2 or edx,esi
1293: 81 ca f0 80 80 80 or edx,0x808080f0
1299: 89 50 fc mov DWORD PTR [rax-0x4],edx
129c: 4c 39 c1 cmp rcx,r8
129f: 0f 82 3b ff ff ff jb 11e0 <utf16_to_utf8+0x20>
12a5: 48 29 f8 sub rax,rdi
12a8: c3 ret
12a9: 90 nop
12aa: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
12b1: 00 00 00 00
12b5: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
12bc: 00 00 00 00
12c0: 0f b7 11 movzx edx,WORD PTR [rcx]
12c3: 83 fa 7f cmp edx,0x7f
12c6: 0f 87 14 ff ff ff ja 11e0 <utf16_to_utf8+0x20>
12cc: 48 83 c1 02 add rcx,0x2
12d0: 48 83 c0 01 add rax,0x1
12d4: 88 50 ff mov BYTE PTR [rax-0x1],dl
12d7: 4c 39 c1 cmp rcx,r8
12da: 72 e4 jb 12c0 <utf16_to_utf8+0x100>
12dc: 48 29 f8 sub rax,rdi
12df: c3 ret
12e0: 0f b7 11 movzx edx,WORD PTR [rcx]
12e3: 81 fa ff 07 00 00 cmp edx,0x7ff
12e9: 0f 86 f1 fe ff ff jbe 11e0 <utf16_to_utf8+0x20>
12ef: 8d b2 00 28 ff ff lea esi,[rdx-0xd800]
12f5: 81 fe ff 07 00 00 cmp esi,0x7ff
12fb: 0f 86 df fe ff ff jbe 11e0 <utf16_to_utf8+0x20>
1301: 8d 34 95 00 00 00 00 lea esi,[rdx*4+0x0]
1308: 41 89 d1 mov r9d,edx
130b: c1 e2 10 shl edx,0x10
130e: 48 83 c1 02 add rcx,0x2
1312: 81 e6 00 3f 00 00 and esi,0x3f00
1318: 41 c1 e9 0c shr r9d,0xc
131c: 81 e2 00 00 3f 00 and edx,0x3f0000
1322: 48 83 c0 03 add rax,0x3
1326: 44 09 ce or esi,r9d
1329: 09 f2 or edx,esi
132b: 81 ca e0 80 80 00 or edx,0x8080e0
1331: 89 50 fd mov DWORD PTR [rax-0x3],edx
1334: 4c 39 c1 cmp rcx,r8
1337: 72 a7 jb 12e0 <utf16_to_utf8+0x120>
1339: 48 29 f8 sub rax,rdi
133c: c3 ret
133d: 0f 1f 00 nop DWORD PTR [rax]
1340: 0f b7 11 movzx edx,WORD PTR [rcx]
1343: 89 d6 mov esi,edx
1345: 83 c6 80 add esi,0xffffff80
1348: 66 81 fe 7f 07 cmp si,0x77f
134d: 0f 87 8d fe ff ff ja 11e0 <utf16_to_utf8+0x20>
1353: 89 d6 mov esi,edx
1355: c1 ea 06 shr edx,0x6
1358: 48 83 c1 02 add rcx,0x2
135c: 48 83 c0 02 add rax,0x2
1360: c1 e6 08 shl esi,0x8
1363: 81 e6 00 3f 00 00 and esi,0x3f00
1369: 09 f2 or edx,esi
136b: 81 ca c0 80 00 00 or edx,0x80c0
1371: 66 89 50 fe mov WORD PTR [rax-0x2],dx
1375: 4c 39 c1 cmp rcx,r8
1378: 72 c6 jb 1340 <utf16_to_utf8+0x180>
137a: 48 29 f8 sub rax,rdi
137d: c3 ret
137e: 31 c0 xor eax,eax
1380: c3 ret
1381: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0]
1388: 48 c7 c0 ff ff ff ff mov rax,0xffffffffffffffff
138f: c3 ret
Disassembly of section .fini:
0000000000001390 <_fini>:
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "callgrind_annotate /tmp/cg_asciimini.out 2>/dev/null | sed -n '1,60p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_asciimini.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 627302
Trigger: Program termination
Profiled target: /tmp/asciitest (PID 1920, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
1,600,009 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
1,600,009 (100.0%) submission/solve.c:utf16_to_utf8 [/tmp/asciitest]
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
. #include <stdint.h>
. #include <stddef.h>
. #include <string.h>
.
. #define INVALID ((size_t)-1)
.
2 ( 0.00%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
2 ( 0.00%) uint8_t *op = out;
. const uint16_t *ip = in;
1 ( 0.00%) const uint16_t *end = in + n;
2 ( 0.00%) while (ip < end) {
1 ( 0.00%) uint32_t c = *ip;
2 ( 0.00%) if (c < 0x80) {
. do {
400,000 (25.00%) *op++ = (uint8_t)c;
200,000 (12.50%) ip++;
999,997 (62.50%) } while (ip < end && (c = *ip) < 0x80);
. } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
. do {
. uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
. memcpy(op, &v, 4);
. op += 3;
. ip++;
. } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
. } else if (c < 0x800) {
-- line 25 ----------------------------------------
-- line 41 ----------------------------------------
. | (cp >> 18);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/asciivec.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <immintrin.h>\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"sse2\")))\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i*)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (!_mm_testz_si128 ? 0 : 0) {} // placeholder\n int mask = _mm_movemask_epi8(_mm_cmpeq_epi16(hi, _mm_setzero_si128()));\n if (mask != 0xFFFF) break;\n __m128i packed = _mm_packus_epi16(v, v);\n _mm_storel_epi64((__m128i*)op, packed);\n ip += 8;\n op += 8;\n }\n if (ip >= end) break;\n c = *ip;\n if (c >= 0x80) goto notascii;\n do {\n *op++ = (uint8_t)c;\n ip++;\n } while (ip < end && (c = *ip) < 0x80);\n continue;\n }\n notascii:;\n c = *ip;\n if (c < 0x80) continue;\n *op++ = 0; // dummy to compile\n ip++;\n }\n return (size_t)(op - out);\n}\nEOF\ncc -O2 -std=c17 -c /tmp/asciivec.c -o /tmp/asciivec.o 2>&1 | head -30"}
tool result
--- Command finished with exit code: 0 ---
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n\n#define INVALID ((size_t)-1)\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);\n _mm_storel_epi64((__m128i *)op, packed);\n ip += 8;\n op += 8;\n }\n if (ip >= end) break;\n c = *ip;\n if (c < 0x80) {\n do {\n *op++ = (uint8_t)c;\n ip++;\n } while (ip < end && (c = *ip) < 0x80);\n }\n } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n do {\n uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);\n memcpy(op, &v, 4);\n op += 3;\n ip++;\n } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));\n } else if (c < 0x800) {\n do {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);\n } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\n", "file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (65 lines):
4+ #include <emmintrin.h>
14- do {
15- *op++ = (uint8_t)c;
16- ip++;
17- } while (ip < end && (c = *ip) < 0x80);
15+ while (ip + 8 <= end) {
16+ __m128i v = _mm_loadu_si128((const __m128i *)ip);
17+ __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
18+ if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
19+ break;
20+ __m128i packed = _mm_packus_epi16(v, v);
21+ _mm_storel_epi64((__m128i *)op, packed);
22+ ip += 8;
23+ op += 8;
24+ }
25+ if (ip >= end) break;
26+ c = *ip;
27+ if (c < 0x80) {
28+ do {
29+ *op++ = (uint8_t)c;
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
51773419
--- Command finished with exit code: 0 ---
assistant
Big improvement. Let's grade.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.6s
verify 2.0s PASS
measure 0.5s 51,772,837 instructions (given: 78,181,481)
SCORE +0.5946 (1.510x)
--- Command finished with exit code: 0 ---
assistant
Let's now vectorize the 3-byte (CJK) path too, since it's the dominant cost.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v6) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg6_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg6_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v6) ==
2050115
== latin (v6) ==
11685528
== cjk (v6) ==
19513661
== emoji (v6) ==
17289728
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/cjkvec.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <tmmintrin.h>\n#include <stdio.h>\n\nint main(void) {\n // test the pshufb-based 4-unit 3-byte encode\n uint16_t units[4] = {0x4E2D, 0x6587, 0x0041, 0x9FFF}; // last one not valid but let's just test math (ignore validity check here)\n // compute expected\n uint8_t expect[12];\n for (int i=0;i<4;i++) {\n uint32_t c = units[i];\n expect[3*i+0] = (uint8_t)(0xE0 | (c>>12));\n expect[3*i+1] = (uint8_t)(0x80 | ((c>>6)&0x3F));\n expect[3*i+2] = (uint8_t)(0x80 | (c&0x3F));\n }\n\n __m128i v = _mm_loadl_epi64((const __m128i*)units); // 4 units in low 64 bits, upper 64 bits zero... actually loadl loads 8 bytes = 4 uint16, upper 64 bits zero-filled? Let's check.\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid);\n __m128i C = _mm_packus_epi16(lo, lo);\n\n __m128i idxAB = _mm_setr_epi8(0,(char)0x80,(char)0x80, 1,(char)0x80,(char)0x80, 2,(char)0x80,(char)0x80, 3,(char)0x80,(char)0x80, (char)0x80,(char)0x80,(char)0x80);\n // AB bytes8-11 = mid0..3, so mid index in AB = 8+i\n __m128i idxAB2 = _mm_setr_epi8(0,8,(char)0x80, 1,9,(char)0x80, 2,10,(char)0x80, 3,11,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n __m128i idxC = _mm_setr_epi8((char)0x80,(char)0x80,0, (char)0x80,(char)0x80,1, (char)0x80,(char)0x80,2, (char)0x80,(char)0x80,3, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n\n __m128i rAB = _mm_shuffle_epi8(AB, idxAB2);\n __m128i rC = _mm_shuffle_epi8(C, idxC);\n __m128i result = _mm_or_si128(rAB, rC);\n\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, result);\n\n printf(\"expect: \");\n for (int i=0;i<12;i++) printf(\"%02x \", expect[i]);\n printf(\"\\ngot: \");\n for (int i=0;i<12;i++) printf(\"%02x \", out[i]);\n printf(\"\\n\");\n int ok = memcmp(expect, out, 12)==0;\n printf(\"match: %d\\n\", ok);\n return !ok;\n}\nEOF\ncc -O2 -std=c17 -mssse3 -o /tmp/cjkvec /tmp/cjkvec.c && /tmp/cjkvec"}
tool result
/tmp/cjkvec.c: In function ‘main’:
/tmp/cjkvec.c:30:21: error: too few arguments to function ‘_mm_setr_epi8’; expected 16, have 15
30 | __m128i idxAB = _mm_setr_epi8(0,(char)0x80,(char)0x80, 1,(char)0x80,(char)0x80, 2,(char)0x80,(char)0x80, 3,(char)0x80,(char)0x80, (char)0x80,(char)0x80,(char)0x80);
| ^~~~~~~~~~~~~
In file included from /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/pmmintrin.h:31,
from /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:31,
from /tmp/cjkvec.c:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:687:1: note: declared here
687 | _mm_setr_epi8 (char __q00, char __q01, char __q02, char __q03,
| ^~~~~~~~~~~~~
--- Command finished with exit code: 1 ---
Exit code: 1
tool call: bash
{"command": "sed -i '/idxAB = _mm_setr_epi8/d' /tmp/cjkvec.c\ncc -O2 -std=c17 -mssse3 -o /tmp/cjkvec /tmp/cjkvec.c && /tmp/cjkvec"}
tool result
expect: e4 b8 ad e6 96 87 e0 81 81 e9 bf bf
got: e4 b8 ad e6 96 87 e0 81 81 e9 bf bf
match: 1
--- Command finished with exit code: 0 ---
assistant
The vectorized 3-byte encoding for 4 units works. Now let's integrate this into solve.c with proper validity range checks (0x800-0xD7FF, 0xE000-0xFFFF).
tool call: bash
{"command": "cat > /tmp/cjkvec2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <tmmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// Test: given 4 code units all in [0x800,0xD7FF] union [0xE000,0xFFFF],\n// vectorized encode to 12 bytes.\nstatic inline __m128i encode4_3byte(__m128i v) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid);\n __m128i C = _mm_packus_epi16(lo, lo);\n\n __m128i idxAB2 = _mm_setr_epi8(0,8,(char)0x80, 1,9,(char)0x80, 2,10,(char)0x80, 3,11,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n __m128i idxC = _mm_setr_epi8((char)0x80,(char)0x80,0, (char)0x80,(char)0x80,1, (char)0x80,(char)0x80,2, (char)0x80,(char)0x80,3, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n\n __m128i rAB = _mm_shuffle_epi8(AB, idxAB2);\n __m128i rC = _mm_shuffle_epi8(C, idxC);\n return _mm_or_si128(rAB, rC);\n}\n\nint main(void) {\n srand(42);\n int bad=0;\n for (int t=0;t<100000;t++) {\n uint16_t units[8];\n for (int i=0;i<8;i++) {\n int r = rand()%2;\n if (r==0) units[i] = 0x800 + rand()%(0xD800-0x800);\n else units[i] = 0xE000 + rand()%(0x10000-0xE000);\n }\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n __m128i result = encode4_3byte(v);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, result);\n uint8_t expect[12];\n for (int i=0;i<4;i++) {\n uint32_t c = units[i];\n expect[3*i+0] = (uint8_t)(0xE0 | (c>>12));\n expect[3*i+1] = (uint8_t)(0x80 | ((c>>6)&0x3F));\n expect[3*i+2] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect, out, 12)!=0) { bad++; }\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -mssse3 -o /tmp/cjkvec2 /tmp/cjkvec2.c && /tmp/cjkvec2"}
tool result
bad=0
--- Command finished with exit code: 0 ---
assistant
Now let's check we can detect "all 8 units in valid 3-byte range" with a fast mask test.
tool call: bash
{"command": "cat > /tmp/cjkmask.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <emmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// check if all 8 units in v are in range [0x800,0xD7FF] union [0xE000,0xFFFF]\n// equivalently: NOT in [0,0x7FF] and NOT in [0xD800,0xDFFF]\nstatic inline int all_3byte(__m128i v) {\n // c < 0x800 -> bad; 0xD800<=c<=0xDFFF -> bad\n __m128i lomask = _mm_cmplt_epi16(v ^ _mm_set1_epi16((short)0x8000), _mm_set1_epi16((short)(0x800 ^ 0x8000))); // unsigned c < 0x800\n // surrogate range test: (c - 0xD800) <= 0x7FF unsigned\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));\n __m128i surrmask = _mm_cmplt_epi16(shifted ^ _mm_set1_epi16((short)0x8000), _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i bad = _mm_or_si128(lomask, surrmask);\n return _mm_movemask_epi8(bad) == 0;\n}\n\nint main(void) {\n srand(1);\n int fails=0;\n for (int t=0;t<1000000;t++) {\n uint16_t units[8];\n int expect_ok = 1;\n for (int i=0;i<8;i++) {\n units[i] = rand() % 0x10000;\n uint32_t c = units[i];\n if (!(c>=0x800 && (c<0xD800 || c>=0xE000))) expect_ok=0;\n }\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n int got = all_3byte(v);\n if (got != expect_ok) fails++;\n }\n printf(\"fails=%d\\n\", fails);\n return fails!=0;\n}\nEOF\ncc -O2 -std=c17 -msse2 -o /tmp/cjkmask /tmp/cjkmask.c && /tmp/cjkmask"}
tool result
fails=0
--- Command finished with exit code: 0 ---
assistant
Both mask check and encode work with pure SSE2/SSSE3. Let's integrate into solve.c.
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <tmmintrin.h>\n\n#define INVALID ((size_t)-1)\n\n// Vectorized encode of 8 code units, all known to be in the \"3-byte\" range\n// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two\n// 12-byte groups).\nstatic inline void encode8_3byte(__m128i v, uint8_t *out) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3\n __m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)\n\n static const __m128i idxAB = { (char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80 };\n static const __m128i idxC = { (char)0x80, (char)0x80, (char)0,\n (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2,\n (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80 };\n\n __m128i rAB = _mm_shuffle_epi8(AB, idxAB);\n __m128i rC = _mm_shuffle_epi8(C, idxC);\n __m128i lo4 = _mm_or_si128(rAB, rC); // bytes for units 0..3, 12 bytes valid\n\n // For units 4..7: hi/mid high 64 bits hold units 4..7 already (from packus\n // second operand ordering: AB high64 = mid0..3, not hi4..7). We need a\n // second pack using the upper halves.\n __m128i hi2 = _mm_srli_si128(hi, 8); // shift so hi4..7 occupy low 64\n __m128i mid2 = _mm_srli_si128(mid, 8);\n __m128i lo2 = _mm_srli_si128(lo, 8);\n __m128i AB2 = _mm_packus_epi16(hi2, mid2);\n __m128i C2 = _mm_packus_epi16(lo2, lo2);\n __m128i rAB2 = _mm_shuffle_epi8(AB2, idxAB);\n __m128i rC2 = _mm_shuffle_epi8(C2, idxC);\n __m128i hi4 = _mm_or_si128(rAB2, rC2);\n\n _mm_storeu_si128((__m128i *)(out + 0), lo4);\n _mm_storeu_si128((__m128i *)(out + 12), hi4);\n}\n\n// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\nstatic inline int all_3byte(__m128i v) {\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));\n __m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i bad = _mm_or_si128(lomask, surrmask);\n return _mm_movemask_epi8(bad) == 0;\n}\n\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n uint8_t *op = out;\n const uint16_t *ip = in;\n const uint16_t *end = in + n;\n while (ip < end) {\n uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);\n _mm_storel_epi64((__m128i *)op, packed);\n ip += 8;\n op += 8;\n }\n if (ip >= end) break;\n c = *ip;\n if (c < 0x80) {\n
... [1967 characters truncated for page size]
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (134 lines):
5+ #include <tmmintrin.h>
9+ // Vectorized encode of 8 code units, all known to be in the "3-byte" range
10+ // (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
11+ // 12-byte groups).
12+ static inline void encode8_3byte(__m128i v, uint8_t *out) {
13+ __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
14+ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
15+ __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
16+ mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
17+ __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
18+ lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
20+ __m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3
21+ __m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)
23+ static const __m128i idxAB = { (char)0, (char)8, (char)0x80,
24+ (char)1, (char)9, (char)0x80,
25+ (char)2, (char)10, (char)0x80,
26+ (char)3, (char)11, (char)0x80,
27+ (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
28+ static const __m128i idxC = { (char)0x80, (char)0x80, (char)0,
29+ (char)0x80, (char)0x80, (char)1,
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && grep -n \"malloc\\|bs\\[\" verify/verify.c | head -20"}
tool result
70: uint8_t bs[64], br[64];
95: uint8_t bs[64], br[64];
139: static uint8_t bs[3 * 2048 + 16], br[3 * 2048 + 16];
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && grep -n \"malloc.*out\\|out = malloc\" verify/runner.c"}
tool result
24: uint8_t *out = malloc(3u * (1u << 21) + 64);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:136:1: error: inlining failed in call to ‘always_inline’ ‘_mm_shuffle_epi8’: target specific option mismatch
136 | _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
| ^~~~~~~~~~~~~~~~
submission/solve.c:34:19: note: called from here
34 | __m128i rAB = _mm_shuffle_epi8(AB, idxAB);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:136:1: error: inlining failed in call to ‘always_inline’ ‘_mm_shuffle_epi8’: target specific option mismatch
136 | _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
| ^~~~~~~~~~~~~~~~
submission/solve.c:35:18: note: called from here
35 | __m128i rC = _mm_shuffle_epi8(C, idxC);
| ^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:136:1: error: inlining failed in call to ‘always_inline’ ‘_mm_shuffle_epi8’: target specific option mismatch
136 | _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
| ^~~~~~~~~~~~~~~~
submission/solve.c:34:19: note: called from here
34 | __m128i rAB = _mm_shuffle_epi8(AB, idxAB);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:136:1: error: inlining failed in call to ‘always_inline’ ‘_mm_shuffle_epi8’: target specific option mismatch
136 | _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
| ^~~~~~~~~~~~~~~~
submission/solve.c:47:19: note: called from here
47 | __m128i rC2 = _mm_shuffle_epi8(C2, idxC);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:136:1: error: inlining failed in call to ‘always_inline’ ‘_mm_shuffle_epi8’: target specific option mismatch
136 | _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
| ^~~~~~~~~~~~~~~~
submission/solve.c:46:20: note: called from here
46 | __m128i rAB2 = _mm_shuffle_epi8(AB2, idxAB);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
--- Command finished with exit code: 0 ---
assistant
Need target attribute or -mssse3 flag. Since grade uses fixed CFLAGS without -mssse3, need `__attribute__((target("ssse3")))`.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "old_string": "static inline void encode8_3byte(__m128i v, uint8_t *out) {", "new_string": "__attribute__((target(\"ssse3\")))\nstatic inline void encode8_3byte(__m128i v, uint8_t *out) {"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
12+ __attribute__((target("ssse3")))
Context after edit (lines 9-16):
9│ // Vectorized encode of 8 code units, all known to be in the "3-byte" range
10│ // (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
11│ // 12-byte groups).
12│ __attribute__((target("ssse3")))
13│ static inline void encode8_3byte(__m128i v, uint8_t *out) {
14│ __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
15│ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
16│ __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
submission/solve.c:31:60: note: (near initialization for ‘idxC’)
submission/solve.c:32:36: warning: excess elements in vector initializer
32 | (char)0x80, (char)0x80, (char)3,
| ^
submission/solve.c:32:36: note: (near initialization for ‘idxC’)
submission/solve.c:32:48: warning: excess elements in vector initializer
32 | (char)0x80, (char)0x80, (char)3,
| ^
submission/solve.c:32:48: note: (near initialization for ‘idxC’)
submission/solve.c:32:60: warning: excess elements in vector initializer
32 | (char)0x80, (char)0x80, (char)3,
| ^
submission/solve.c:32:60: note: (near initialization for ‘idxC’)
submission/solve.c:33:36: warning: excess elements in vector initializer
33 | (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
| ^
submission/solve.c:33:36: note: (near initialization for ‘idxC’)
submission/solve.c:33:48: warning: excess elements in vector initializer
33 | (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
| ^
submission/solve.c:33:48: note: (near initialization for ‘idxC’)
submission/solve.c:33:60: warning: excess elements in vector initializer
33 | (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
| ^
submission/solve.c:33:60: note: (near initialization for ‘idxC’)
submission/solve.c:33:72: warning: excess elements in vector initializer
33 | (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
| ^
submission/solve.c:33:72: note: (near initialization for ‘idxC’)
43373430
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxC = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,\n (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2,\n (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);", "old_string": " static const __m128i idxAB = { (char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80 };\n static const __m128i idxC = { (char)0x80, (char)0x80, (char)0,\n (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2,\n (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80 };"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
24- static const __m128i idxAB = { (char)0, (char)8, (char)0x80,
25- (char)1, (char)9, (char)0x80,
26- (char)2, (char)10, (char)0x80,
27- (char)3, (char)11, (char)0x80,
28- (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
29- static const __m128i idxC = { (char)0x80, (char)0x80, (char)0,
30- (char)0x80, (char)0x80, (char)1,
31- (char)0x80, (char)0x80, (char)2,
32- (char)0x80, (char)0x80, (char)3,
33- (char)0x80, (char)0x80, (char)0x80, (char)0x80 };
24+ const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,
25+ (char)1, (char)9, (char)0x80,
26+ (char)2, (char)10, (char)0x80,
27+ (char)3, (char)11, (char)0x80,
28+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
29+ const __m128i idxC = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
30+ (char)0x80, (char)0x80, (char)1,
31+ (char)0x80, (char)0x80, (char)2,
32+ (char)0x80, (char)0x80, (char)3,
33+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
Context after edit (lines 21-36):
21│ __m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3
22│ __m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)
23│
24│ const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,
25│ (char)1, (char)9, (char)0x80,
26│ (char)2, (char)10, (char)0x80,
27│ (char)3, (char)11, (char)0x80,
28│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
29│ const __m128i idxC = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
30│ (char)0x80, (char)0x80, (char)1,
31│ (char)0x80, (char)0x80, (char)2,
32│ (char)0x80, (char)0x80, (char)3,
33│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
34│
35│ __m128i rAB = _mm_shuffle_epi8(AB, idxAB);
36│ __m128i rC = _mm_shuffle_epi8(C, idxC);
assistant
Now I need to check where all_3byte and encode8_3byte and the main function need target attribute too since they call ssse3 intrinsics indirectly. Let's also add target to utf16_to_utf8 itself for the whole function, and check all_3byte only needs SSE2.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
43351970
--- Command finished with exit code: 0 ---
assistant
Compiles now. Let's grade for correctness first.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 0.6s
verify 1.9s PASS
measure 0.4s 43,351,388 instructions (given: 78,181,481)
SCORE +0.8507 (1.803x)
--- Command finished with exit code: 0 ---
assistant
Excellent progress. Let's continue profiling.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v7) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg7_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg7_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v7) ==
2050150
== latin (v7) ==
11861088
== cjk (v7) ==
10800310
== emoji (v7) ==
17483801
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/latinvec.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <tmmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// encode 8 units in [0x80,0x7FF] to 16 bytes\n__attribute__((target(\"ssse3\")))\nstatic inline __m128i encode8_2byte(__m128i v) {\n __m128i hi = _mm_srli_epi16(v, 6);\n hi = _mm_or_si128(hi, _mm_set1_epi16((short)0xFFC0));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16((short)0xFF80));\n // interleave hi,lo per 16-bit lane -> byte pairs\n __m128i hib = _mm_packus_epi16(hi, hi); // low 64 = hi bytes 0..7 (dup)\n __m128i lob = _mm_packus_epi16(lo, lo);\n __m128i result = _mm_unpacklo_epi8(hib, lob); // interleave low 64 bits: h0 l0 h1 l1...\n return result;\n}\n\nint main(void) {\n srand(7);\n int bad=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[8];\n for (int i=0;i<8;i++) units[i] = 0x80 + rand()%(0x800-0x80);\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n __m128i r = encode8_2byte(v);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, r);\n uint8_t expect[16];\n for (int i=0;i<8;i++) {\n uint32_t c = units[i];\n expect[2*i+0] = (uint8_t)(0xC0 | (c>>6));\n expect[2*i+1] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect,out,16)!=0) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/latinvec /tmp/latinvec.c && /tmp/latinvec"}
tool result
bad=200000
--- Command finished with exit code: 1 ---
Exit code: 1
tool call: bash
{"command": "cat >> /tmp/latinvec.c << 'EOF'\nEOF\nsed -n '1,40p' /tmp/latinvec.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <tmmintrin.h>
#include <stdio.h>
#include <stdlib.h>
// encode 8 units in [0x80,0x7FF] to 16 bytes
__attribute__((target("ssse3")))
static inline __m128i encode8_2byte(__m128i v) {
__m128i hi = _mm_srli_epi16(v, 6);
hi = _mm_or_si128(hi, _mm_set1_epi16((short)0xFFC0));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16((short)0xFF80));
// interleave hi,lo per 16-bit lane -> byte pairs
__m128i hib = _mm_packus_epi16(hi, hi); // low 64 = hi bytes 0..7 (dup)
__m128i lob = _mm_packus_epi16(lo, lo);
__m128i result = _mm_unpacklo_epi8(hib, lob); // interleave low 64 bits: h0 l0 h1 l1...
return result;
}
int main(void) {
srand(7);
int bad=0;
for (int t=0;t<200000;t++) {
uint16_t units[8];
for (int i=0;i<8;i++) units[i] = 0x80 + rand()%(0x800-0x80);
__m128i v = _mm_loadu_si128((const __m128i*)units);
__m128i r = encode8_2byte(v);
uint8_t out[16];
_mm_storeu_si128((__m128i*)out, r);
uint8_t expect[16];
for (int i=0;i<8;i++) {
uint32_t c = units[i];
expect[2*i+0] = (uint8_t)(0xC0 | (c>>6));
expect[2*i+1] = (uint8_t)(0x80 | (c&0x3F));
}
if (memcmp(expect,out,16)!=0) bad++;
}
printf("bad=%d\n", bad);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/latinvec2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <tmmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"ssse3\")))\nstatic inline __m128i encode8_2byte(__m128i v) {\n __m128i hi = _mm_srli_epi16(v, 6);\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n __m128i hib = _mm_packus_epi16(hi, hi);\n __m128i lob = _mm_packus_epi16(lo, lo);\n __m128i result = _mm_unpacklo_epi8(hib, lob);\n return result;\n}\n\nint main(void) {\n srand(7);\n int bad=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[8];\n for (int i=0;i<8;i++) units[i] = 0x80 + rand()%(0x800-0x80);\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n __m128i r = encode8_2byte(v);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, r);\n uint8_t expect[16];\n for (int i=0;i<8;i++) {\n uint32_t c = units[i];\n expect[2*i+0] = (uint8_t)(0xC0 | (c>>6));\n expect[2*i+1] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect,out,16)!=0) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/latinvec2 /tmp/latinvec2.c && /tmp/latinvec2"}
tool result
bad=0
--- Command finished with exit code: 0 ---
assistant
The bit was off since 0xC0 should be OR'd as low bits not high (packus truncates to unsigned bytes correctly with lower bits). Now integrate this into solve.c for the 2-byte path.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": "// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\nstatic inline int all_3byte(__m128i v) {\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));\n __m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i bad = _mm_or_si128(lomask, surrmask);\n return _mm_movemask_epi8(bad) == 0;\n}\n\n// True iff all 8 code units in v are in [0x0080,0x07FF].\nstatic inline int all_2byte(__m128i v) {\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));\n __m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),\n _mm_set1_epi16((short)(0x0780 ^ 0x8000)));\n return _mm_movemask_epi8(inrange) == 0xFFFF;\n}\n\n// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to\n// 16 bytes of UTF-8.\n__attribute__((target(\"ssse3\")))\nstatic inline __m128i encode8_2byte(__m128i v) {\n __m128i hi = _mm_srli_epi16(v, 6);\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n __m128i hib = _mm_packus_epi16(hi, hi);\n __m128i lob = _mm_packus_epi16(lo, lo);\n return _mm_unpacklo_epi8(hib, lob);\n}\n", "old_string": "// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\nstatic inline int all_3byte(__m128i v) {\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));\n __m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i bad = _mm_or_si128(lomask, surrmask);\n return _mm_movemask_epi8(bad) == 0;\n}"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
65- }
65+ }
67+ // True iff all 8 code units in v are in [0x0080,0x07FF].
68+ static inline int all_2byte(__m128i v) {
69+ __m128i sbit = _mm_set1_epi16((short)0x8000);
70+ __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
71+ __m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
72+ _mm_set1_epi16((short)(0x0780 ^ 0x8000)));
73+ return _mm_movemask_epi8(inrange) == 0xFFFF;
74+ }
76+ // Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
77+ // 16 bytes of UTF-8.
78+ __attribute__((target("ssse3")))
79+ static inline __m128i encode8_2byte(__m128i v) {
80+ __m128i hi = _mm_srli_epi16(v, 6);
81+ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
82+ __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
83+ lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
84+ __m128i hib = _mm_packus_epi16(hi, hi);
85+ __m128i lob = _mm_packus_epi16(lo, lo);
86+ return _mm_unpacklo_epi8(hib, lob);
87+ }
Context after edit (lines 52-90):
52│ _mm_storeu_si128((__m128i *)(out + 12), hi4);
53│ }
54│
55│ // True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
56│ static inline int all_3byte(__m128i v) {
57│ __m128i sbit = _mm_set1_epi16((short)0x8000);
58│ __m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
59│ _mm_set1_epi16((short)(0x800 ^ 0x8000)));
60│ __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
61│ __m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
62│ _mm_set1_epi16((short)(0x800 ^ 0x8000)));
63│ __m128i bad = _mm_or_si128(lomask, surrmask);
64│ return _mm_movemask_epi8(bad) == 0;
65│ }
66│
67│ // True iff all 8 code units in v are in [0x0080,0x07FF].
68│ static inline int all_2byte(__m128i v) {
69│ __m128i sbit = _mm_set1_epi16((short)0x8000);
70│ __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
71│ __m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
72│ _mm_set1_epi16((short)(0x0780 ^ 0x8000)));
73│ return _mm_movemask_epi8(inrange) == 0xFFFF;
74│ }
75│
76│ // Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
77│ // 16 bytes of UTF-8.
78│ __attribute__((target("ssse3")))
79│ static inline __m128i encode8_2byte(__m128i v) {
80│ __m128i hi = _mm_srli_epi16(v, 6);
81│ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
82│ __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
83│ lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
84│ __m128i hib = _mm_packus_epi16(hi, hi);
85│ __m128i lob = _mm_packus_epi16(lo, lo);
86│ return _mm_unpacklo_epi8(hib, lob);
87│ }
88│
89│
90│ size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
assistant
Now update the 2-byte encoding path in the main loop to use this vectorized version.
tool call: bash
{"command": "sed -n '90,145p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " } else if (c < 0x800) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n if (!all_2byte(v)) break;\n __m128i r = encode8_2byte(v);\n _mm_storeu_si128((__m128i *)op, r);\n ip += 8;\n op += 16;\n }\n if (ip >= end) break;\n c = *ip;\n if (c >= 0x80 && c < 0x800) {\n do {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);\n }\n } else if (c < 0xDC00) {", "old_string": " } else if (c < 0x800) {\n do {\n uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);\n memcpy(op, &v, 2);\n op += 2;\n ip++;\n } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);\n } else if (c < 0xDC00) {"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
134- do {
135- uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
136- memcpy(op, &v, 2);
137- op += 2;
138- ip++;
139- } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
134+ while (ip + 8 <= end) {
135+ __m128i v = _mm_loadu_si128((const __m128i *)ip);
136+ if (!all_2byte(v)) break;
137+ __m128i r = encode8_2byte(v);
138+ _mm_storeu_si128((__m128i *)op, r);
139+ ip += 8;
140+ op += 16;
141+ }
142+ if (ip >= end) break;
143+ c = *ip;
144+ if (c >= 0x80 && c < 0x800) {
145+ do {
146+ uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
147+ memcpy(op, &v, 2);
148+ op += 2;
149+ ip++;
150+ } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
151+ }
Context after edit (lines 130-155):
130│ ip++;
131│ } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
132│ }
133│ } else if (c < 0x800) {
134│ while (ip + 8 <= end) {
135│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
136│ if (!all_2byte(v)) break;
137│ __m128i r = encode8_2byte(v);
138│ _mm_storeu_si128((__m128i *)op, r);
139│ ip += 8;
140│ op += 16;
141│ }
142│ if (ip >= end) break;
143│ c = *ip;
144│ if (c >= 0x80 && c < 0x800) {
145│ do {
146│ uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
147│ memcpy(op, &v, 2);
148│ op += 2;
149│ ip++;
150│ } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
151│ }
152│ } else if (c < 0xDC00) {
153│ if (ip + 1 >= end) return INVALID;
154│ uint32_t lo = ip[1];
155│ if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
39055026
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 0.6s
verify 2.0s PASS
measure 0.4s 39,054,874 instructions (given: 78,181,481)
SCORE +1.0013 (2.002x)
--- Command finished with exit code: 0 ---
assistant
2x already. Let's keep going: try vectorizing the surrogate/emoji path and improve tail handling.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v8) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg8_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg8_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v8) ==
2050141
== latin (v8) ==
8477993
== cjk (v8) ==
10919318
== emoji (v8) ==
17400632
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#define INVALID ((size_t)-1)
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3
__m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)
const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,
(char)1, (char)9, (char)0x80,
(char)2, (char)10, (char)0x80,
(char)3, (char)11, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
(char)0x80, (char)0x80, (char)1,
(char)0x80, (char)0x80, (char)2,
(char)0x80, (char)0x80, (char)3,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
__m128i rAB = _mm_shuffle_epi8(AB, idxAB);
__m128i rC = _mm_shuffle_epi8(C, idxC);
__m128i lo4 = _mm_or_si128(rAB, rC); // bytes for units 0..3, 12 bytes valid
// For units 4..7: hi/mid high 64 bits hold units 4..7 already (from packus
// second operand ordering: AB high64 = mid0..3, not hi4..7). We need a
// second pack using the upper halves.
__m128i hi2 = _mm_srli_si128(hi, 8); // shift so hi4..7 occupy low 64
__m128i mid2 = _mm_srli_si128(mid, 8);
__m128i lo2 = _mm_srli_si128(lo, 8);
__m128i AB2 = _mm_packus_epi16(hi2, mid2);
__m128i C2 = _mm_packus_epi16(lo2, lo2);
__m128i rAB2 = _mm_shuffle_epi8(AB2, idxAB);
__m128i rC2 = _mm_shuffle_epi8(C2, idxC);
__m128i hi4 = _mm_or_si128(rAB2, rC2);
_mm_storeu_si128((__m128i *)(out + 0), lo4);
_mm_storeu_si128((__m128i *)(out + 12), hi4);
}
// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
static inline int all_3byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
__m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i bad = _mm_or_si128(lomask, surrmask);
return _mm_movemask_epi8(bad) == 0;
}
// True iff all 8 code units in v are in [0x0080,0x07FF].
static inline int all_2byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
__m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x0780 ^ 0x8000)));
return _mm_movemask_epi8(inrange) == 0xFFFF;
}
// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
// 16 bytes of UTF-8.
__attribute__((target("ssse3")))
static inline __m128i encode8_2byte(__m128i v) {
__m128i hi = _mm_srli_epi16(v, 6);
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i hib = _mm_packus_epi16(hi, hi);
__m128i lob = _mm_packus_epi16(lo, lo);
return _mm_unpacklo_epi8(hib, lob);
}
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
}
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/surrvec.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// v: 8x16-bit units = 4 surrogate pairs (h0,l0,h1,l1,h2,l2,h3,l3).\n// Equivalently, viewed as 4x32-bit lanes x_i = h_i | (l_i<<16).\nstatic inline int all_surrogate_pairs(__m128i v) {\n __m128i sbit32 = _mm_set1_epi32((int)0x80000000u);\n __m128i himask = _mm_set1_epi32(0xFFFF);\n __m128i hi = _mm_and_si128(v, himask); // h_i in low 16 bits per lane\n __m128i lo = _mm_srli_epi32(v, 16); // l_i\n __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));\n __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));\n __m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),\n _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));\n __m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),\n _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));\n __m128i allok = _mm_and_si128(hi_ok, lo_ok);\n return _mm_movemask_epi8(allok) == 0xFFFF;\n}\n\nstatic inline __m128i encode4_pairs(__m128i v) {\n __m128i himask = _mm_set1_epi32(0xFFFF);\n __m128i hi = _mm_and_si128(v, himask);\n __m128i lo = _mm_srli_epi32(v, 16);\n __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));\n __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));\n __m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj), _mm_set1_epi32(0x10000));\n\n __m128i b0 = _mm_srli_epi32(cp, 18);\n __m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));\n __m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));\n __m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));\n\n __m128i word = _mm_set1_epi32((int)0x808080F0u);\n word = _mm_or_si128(word, b0);\n word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));\n word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));\n word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));\n return word;\n}\n\nint main(void) {\n srand(3);\n int bad = 0, badv = 0;\n for (int t = 0; t < 500000; t++) {\n uint16_t units[8];\n uint32_t cps[4];\n for (int i = 0; i < 4; i++) {\n uint32_t cp = 0x10000 + rand() % (0x110000 - 0x10000);\n cps[i] = cp;\n uint32_t cpp = cp - 0x10000;\n units[2*i] = 0xD800 + (cpp >> 10);\n units[2*i+1] = 0xDC00 + (cpp & 0x3FF);\n }\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n int ok = all_surrogate_pairs(v);\n if (!ok) { bad++; continue; }\n __m128i r = encode4_pairs(v);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, r);\n uint8_t expect[16];\n for (int i = 0; i < 4; i++) {\n uint32_t cp = cps[i];\n expect[4*i+0] = (uint8_t)(0xF0 | (cp>>18));\n expect[4*i+1] = (uint8_t)(0x80 | ((cp>>12)&0x3F));\n expect[4*i+2] = (uint8_t)(0x80 | ((cp>>6)&0x3F));\n expect[4*i+3] = (uint8_t)(0x80 | (cp&0x3F));\n }\n if (memcmp(expect, out, 16) != 0) badv++;\n }\n printf(\"bad=%d badv=%d\\n\", bad, badv);\n return bad != 0 || badv != 0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/surrvec /tmp/surrvec.c && /tmp/surrvec"}
tool result
bad=0 badv=0
--- Command finished with exit code: 0 ---
assistant
That works. Now integrate this into solve.c for the surrogate-pair emoji path.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": "// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to\n// 16 bytes of UTF-8.\n__attribute__((target(\"ssse3\")))\nstatic inline __m128i encode8_2byte(__m128i v) {\n __m128i hi = _mm_srli_epi16(v, 6);\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n __m128i hib = _mm_packus_epi16(hi, hi);\n __m128i lob = _mm_packus_epi16(lo, lo);\n return _mm_unpacklo_epi8(hib, lob);\n}\n\n// v holds 4 packed 32-bit lanes, each (hi<<0)|(lo<<16) i.e. loaded from 4\n// consecutive (high,low) surrogate pairs. True iff all 4 pairs are valid\n// (hi in [0xD800,0xDBFF], lo in [0xDC00,0xDFFF]).\nstatic inline int all_surrogate_pairs(__m128i v) {\n __m128i sbit32 = _mm_set1_epi32((int)0x80000000u);\n __m128i himask = _mm_set1_epi32(0xFFFF);\n __m128i hi = _mm_and_si128(v, himask);\n __m128i lo = _mm_srli_epi32(v, 16);\n __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));\n __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));\n __m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),\n _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));\n __m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),\n _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));\n __m128i allok = _mm_and_si128(hi_ok, lo_ok);\n return _mm_movemask_epi8(allok) == 0xFFFF;\n}\n\n// Vectorized encode of 4 valid surrogate pairs (packed as in\n// all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).\nstatic inline __m128i encode4_pairs(__m128i v) {\n __m128i himask = _mm_set1_epi32(0xFFFF);\n __m128i hi = _mm_and_si128(v, himask);\n __m128i lo = _mm_srli_epi32(v, 16);\n __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));\n __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));\n __m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj),\n _mm_set1_epi32(0x10000));\n\n __m128i b0 = _mm_srli_epi32(cp, 18);\n __m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));\n __m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));\n __m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));\n\n __m128i word = _mm_set1_epi32((int)0x808080F0u);\n word = _mm_or_si128(word, b0);\n word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));\n word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));\n word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));\n return word;\n}\n\n", "old_string": "// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to\n// 16 bytes of UTF-8.\n__attribute__((target(\"ssse3\")))\nstatic inline __m128i encode8_2byte(__m128i v) {\n __m128i hi = _mm_srli_epi16(v, 6);\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n __m128i hib = _mm_packus_epi16(hi, hi);\n __m128i lob = _mm_packus_epi16(lo, lo);\n return _mm_unpacklo_epi8(hib, lob);\n}\n\n"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
89+ // v holds 4 packed 32-bit lanes, each (hi<<0)|(lo<<16) i.e. loaded from 4
90+ // consecutive (high,low) surrogate pairs. True iff all 4 pairs are valid
91+ // (hi in [0xD800,0xDBFF], lo in [0xDC00,0xDFFF]).
92+ static inline int all_surrogate_pairs(__m128i v) {
93+ __m128i sbit32 = _mm_set1_epi32((int)0x80000000u);
94+ __m128i himask = _mm_set1_epi32(0xFFFF);
95+ __m128i hi = _mm_and_si128(v, himask);
96+ __m128i lo = _mm_srli_epi32(v, 16);
97+ __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
98+ __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
99+ __m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),
100+ _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
101+ __m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),
102+ _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
103+ __m128i allok = _mm_and_si128(hi_ok, lo_ok);
104+ return _mm_movemask_epi8(allok) == 0xFFFF;
105+ }
107+ // Vectorized encode of 4 valid surrogate pairs (packed as in
108+ // all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).
109+ static inline __m128i encode4_pairs(__m128i v) {
110+ __m128i himask = _mm_set1_epi32(0xFFFF);
111+ __m128i hi = _mm_and_si128(v, himask);
112+ __m128i lo = _mm_srli_epi32(v, 16);
113+ __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
114+ __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
115+ __m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj),
116+ _mm_set1_epi32(0x10000));
118+ __m128i b0 = _mm_srli_epi32(cp, 18);
119+ __m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));
120+ __m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));
121+ __m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));
123+ __m128i word = _mm_set1_epi32((int)0x808080F0u);
124+ word = _mm_or_si128(word, b0);
125+ word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
126+ word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
127+ word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
128+ return word;
129+ }
Context after edit (lines 73-133):
73│ return _mm_movemask_epi8(inrange) == 0xFFFF;
74│ }
75│
76│ // Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
77│ // 16 bytes of UTF-8.
78│ __attribute__((target("ssse3")))
79│ static inline __m128i encode8_2byte(__m128i v) {
80│ __m128i hi = _mm_srli_epi16(v, 6);
81│ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
82│ __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
83│ lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
84│ __m128i hib = _mm_packus_epi16(hi, hi);
85│ __m128i lob = _mm_packus_epi16(lo, lo);
86│ return _mm_unpacklo_epi8(hib, lob);
87│ }
88│
89│ // v holds 4 packed 32-bit lanes, each (hi<<0)|(lo<<16) i.e. loaded from 4
90│ // consecutive (high,low) surrogate pairs. True iff all 4 pairs are valid
91│ // (hi in [0xD800,0xDBFF], lo in [0xDC00,0xDFFF]).
92│ static inline int all_surrogate_pairs(__m128i v) {
93│ __m128i sbit32 = _mm_set1_epi32((int)0x80000000u);
94│ __m128i himask = _mm_set1_epi32(0xFFFF);
95│ __m128i hi = _mm_and_si128(v, himask);
96│ __m128i lo = _mm_srli_epi32(v, 16);
97│ __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
98│ __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
99│ __m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),
100│ _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
101│ __m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),
102│ _mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
103│ __m128i allok = _mm_and_si128(hi_ok, lo_ok);
104│ return _mm_movemask_epi8(allok) == 0xFFFF;
105│ }
106│
107│ // Vectorized encode of 4 valid surrogate pairs (packed as in
108│ // all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).
109│ static inline __m128i encode4_pairs(__m128i v) {
110│ __m128i himask = _mm_set1_epi32(0xFFFF);
111│ __m128i hi = _mm_and_si128(v, himask);
112│ __m128i lo = _mm_srli_epi32(v, 16);
113│ __m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
114│ __m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
115│ __m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj),
116│ _mm_set1_epi32(0x10000));
117│
118│ __m128i b0 = _mm_srli_epi32(cp, 18);
119│ __m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));
120│ __m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));
121│ __m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));
122│
123│ __m128i word = _mm_set1_epi32((int)0x808080F0u);
124│ word = _mm_or_si128(word, b0);
125│ word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
126│ word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
127│ word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
128│ return word;
129│ }
130│
131│
132│ size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
133│ uint8_t *op = out;
assistant
Now update the surrogate handling branch to try vectorized batch processing when we hit a high surrogate.
tool call: bash
{"command": "sed -n '165,190p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '195,220p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n if (!all_surrogate_pairs(v)) break;\n __m128i r = encode4_pairs(v);\n _mm_storeu_si128((__m128i *)op, r);\n ip += 8;\n op += 16;\n }\n if (ip >= end) break;\n c = *ip;\n if (c >= 0xD800 && c < 0xDC00) {\n do {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo2 = ip[1];\n if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);\n } else if (ip < end && c >= 0xDC00 && c < 0xE000) {\n return INVALID;\n }\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}\n", "old_string": " if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);\n uint32_t v = 0x808080F0u\n | ((cp & 0x3F) << 24)\n | (((cp >> 6) & 0x3F) << 16)\n | (((cp >> 12) & 0x3F) << 8)\n | (cp >> 18);\n memcpy(op, &v, 4);\n op += 4;\n ip += 2;\n } else {\n return INVALID;\n }\n }\n return (size_t)(op - out);\n}"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
198- uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
199- uint32_t v = 0x808080F0u
200- | ((cp & 0x3F) << 24)
201- | (((cp >> 6) & 0x3F) << 16)
202- | (((cp >> 12) & 0x3F) << 8)
203- | (cp >> 18);
204- memcpy(op, &v, 4);
205- op += 4;
206- ip += 2;
198+ while (ip + 8 <= end) {
199+ __m128i v = _mm_loadu_si128((const __m128i *)ip);
200+ if (!all_surrogate_pairs(v)) break;
201+ __m128i r = encode4_pairs(v);
202+ _mm_storeu_si128((__m128i *)op, r);
203+ ip += 8;
204+ op += 16;
205+ }
206+ if (ip >= end) break;
207+ c = *ip;
208+ if (c >= 0xD800 && c < 0xDC00) {
209+ do {
210+ if (ip + 1 >= end) return INVALID;
211+ uint32_t lo2 = ip[1];
212+ if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
213+ uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
214+ uint32_t v = 0x808080F0u
215+ | ((cp & 0x3F) << 24)
216+ | (((cp >> 6) & 0x3F) << 16)
217+ | (((cp >> 12) & 0x3F) << 8)
218+ | (cp >> 18);
219+ memcpy(op, &v, 4);
220+ op += 4;
221+ ip += 2;
222+ } while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
223+ } else if (ip < end && c >= 0xDC00 && c < 0xE000) {
224+ return INVALID;
225+ }
212- }
231+ }
Context after edit (lines 192-232):
192│ } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
193│ }
194│ } else if (c < 0xDC00) {
195│ if (ip + 1 >= end) return INVALID;
196│ uint32_t lo = ip[1];
197│ if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
198│ while (ip + 8 <= end) {
199│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
200│ if (!all_surrogate_pairs(v)) break;
201│ __m128i r = encode4_pairs(v);
202│ _mm_storeu_si128((__m128i *)op, r);
203│ ip += 8;
204│ op += 16;
205│ }
206│ if (ip >= end) break;
207│ c = *ip;
208│ if (c >= 0xD800 && c < 0xDC00) {
209│ do {
210│ if (ip + 1 >= end) return INVALID;
211│ uint32_t lo2 = ip[1];
212│ if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
213│ uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
214│ uint32_t v = 0x808080F0u
215│ | ((cp & 0x3F) << 24)
216│ | (((cp >> 6) & 0x3F) << 16)
217│ | (((cp >> 12) & 0x3F) << 8)
218│ | (cp >> 18);
219│ memcpy(op, &v, 4);
220│ op += 4;
221│ ip += 2;
222│ } while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
223│ } else if (ip < end && c >= 0xDC00 && c < 0xE000) {
224│ return INVALID;
225│ }
226│ } else {
227│ return INVALID;
228│ }
229│ }
230│ return (size_t)(op - out);
231│ }
232│
tool call: bash
{"command": "cat -n /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | sed -n '130,232p'"}
tool result
130
131
132 size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
133 uint8_t *op = out;
134 const uint16_t *ip = in;
135 const uint16_t *end = in + n;
136 while (ip < end) {
137 uint32_t c = *ip;
138 if (c < 0x80) {
139 while (ip + 8 <= end) {
140 __m128i v = _mm_loadu_si128((const __m128i *)ip);
141 __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
142 if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
143 break;
144 __m128i packed = _mm_packus_epi16(v, v);
145 _mm_storel_epi64((__m128i *)op, packed);
146 ip += 8;
147 op += 8;
148 }
149 if (ip >= end) break;
150 c = *ip;
151 if (c < 0x80) {
152 do {
153 *op++ = (uint8_t)c;
154 ip++;
155 } while (ip < end && (c = *ip) < 0x80);
156 }
157 } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
158 while (ip + 8 <= end) {
159 __m128i v = _mm_loadu_si128((const __m128i *)ip);
160 if (!all_3byte(v)) break;
161 encode8_3byte(v, op);
162 ip += 8;
163 op += 24;
164 }
165 if (ip >= end) break;
166 c = *ip;
167 if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
168 do {
169 uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
170 memcpy(op, &v, 4);
171 op += 3;
172 ip++;
173 } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
174 }
175 } else if (c < 0x800) {
176 while (ip + 8 <= end) {
177 __m128i v = _mm_loadu_si128((const __m128i *)ip);
178 if (!all_2byte(v)) break;
179 __m128i r = encode8_2byte(v);
180 _mm_storeu_si128((__m128i *)op, r);
181 ip += 8;
182 op += 16;
183 }
184 if (ip >= end) break;
185 c = *ip;
186 if (c >= 0x80 && c < 0x800) {
187 do {
188 uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
189 memcpy(op, &v, 2);
190 op += 2;
191 ip++;
192 } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
193 }
194 } else if (c < 0xDC00) {
195 if (ip + 1 >= end) return INVALID;
196 uint32_t lo = ip[1];
197 if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
198 while (ip + 8 <= end) {
199 __m128i v = _mm_loadu_si128((const __m128i *)ip);
200 if (!all_surrogate_pairs(v)) break;
201 __m128i r = encode4_pairs(v);
202 _mm_storeu_si128((__m128i *)op, r);
203 ip += 8;
204 op += 16;
205 }
206 if (ip >= end) break;
207 c = *ip;
208 if (c >= 0xD800 && c < 0xDC00) {
209 do {
210 if (ip + 1 >= end) return INVALID;
211 uint32_t lo2 = ip[1];
212 if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
213 uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
214 uint32_t v = 0x808080F0u
215 | ((cp & 0x3F) << 24)
216 | (((cp >> 6) & 0x3F) << 16)
217 | (((cp >> 12) & 0x3F) << 8)
218 | (cp >> 18);
219 memcpy(op, &v, 4);
220 op += 4;
221 ip += 2;
222 } while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
223 } else if (ip < end && c >= 0xDC00 && c < 0xE000) {
224 return INVALID;
225 }
226 } else {
227 return INVALID;
228 }
229 }
230 return (size_t)(op - out);
231 }
232
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;\n (void)lo;", "old_string": " } else if (c < 0xDC00) {\n if (ip + 1 >= end) return INVALID;\n uint32_t lo = ip[1];\n if (lo < 0xDC00 || lo >= 0xE000) return INVALID;"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
197- if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
197+ if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
198+ (void)lo;
Context after edit (lines 191-201):
191│ ip++;
192│ } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
193│ }
194│ } else if (c < 0xDC00) {
195│ if (ip + 1 >= end) return INVALID;
196│ uint32_t lo = ip[1];
197│ if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
198│ (void)lo;
199│ while (ip + 8 <= end) {
200│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
201│ if (!all_surrogate_pairs(v)) break;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
35445531
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 0.7s
verify 1.9s PASS
measure 0.4s 35,445,431 instructions (given: 78,181,481)
SCORE +1.1412 (2.206x)
--- Command finished with exit code: 0 ---
assistant
2.2x. Let's check the "else if (ip < end && c >= 0xDC00...)" branch is correct - actually this checks after loop broke, but is that even reachable properly? Let's verify full gate and continue profiling.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full --seed 1 2>&1 | tail -20"}
tool result
build 0.7s
verify 1.9s PASS (FULL gate)
measure 0.4s 35,445,431 instructions (given: 78,181,481)
SCORE +1.1412 (2.206x)
--- Command finished with exit code: 0 ---
assistant
Good, full gate passes. Let's check for edge case: c after break from vectorized loop might be in DC00-E000 range but that path is unreachable given the outer condition c<0xDC00 already established. Let's simplify/verify.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && sed -n '194,226p' submission/solve.c"}
tool result
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
(void)lo;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
} else if (ip < end && c >= 0xDC00 && c < 0xE000) {
return INVALID;
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (v9) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg9_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg9_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (v9) ==
2050145
== latin (v9) ==
8777869
== cjk (v9) ==
10895661
== emoji (v9) ==
12087393
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '28,100p'"}
tool result
729,640 (11.14%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_3byte [/tmp/runner_cur]
201,648 ( 3.08%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_2byte [/tmp/runner_cur]
128,760 ( 1.97%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:encode8_3byte
--------------------------------------------------------------------------------
-- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h
--------------------------------------------------------------------------------
Ir
-- line 699 ----------------------------------------
. _mm_load_si128 (__m128i const *__P)
. {
. return *__P;
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_loadu_si128 (__m128i_u const *__P)
. {
150,162 ( 2.29%) return *__P;
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_loadl_epi64 (__m128i_u const *__P)
. {
. return _mm_set_epi64 ((__m64)0LL, *(__m64_u *)__P);
. }
.
-- line 715 ----------------------------------------
-- line 735 ----------------------------------------
. _mm_store_si128 (__m128i *__P, __m128i __B)
. {
. *__P = __B;
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storeu_si128 (__m128i_u *__P, __m128i __B)
. {
66,001 ( 1.01%) *__P = __B;
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storel_epi64 (__m128i_u *__P, __m128i __B)
. {
62,592 ( 0.96%) *(__m64_u *)__P = (__m64) ((__v2di)__B)[0];
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storeu_si64 (void *__P, __m128i __B)
. {
. _mm_storel_epi64 ((__m128i_u *)__P, __B);
. }
.
-- line 757 ----------------------------------------
-- line 999 ----------------------------------------
. _mm_packs_epi32 (__m128i __A, __m128i __B)
. {
. return (__m128i)__builtin_ia32_packssdw128 ((__v4si)__A, (__v4si)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_packus_epi16 (__m128i __A, __m128i __B)
. {
229,161 ( 3.50%) return (__m128i)__builtin_ia32_packuswb128 ((__v8hi)__A, (__v8hi)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_unpackhi_epi8 (__m128i __A, __m128i __B)
. {
. return (__m128i)__builtin_ia32_punpckhbw128 ((__v16qi)__A, (__v16qi)__B);
. }
.
-- line 1015 ----------------------------------------
-- line 1065 ----------------------------------------
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/cjkvec3.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <tmmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"ssse3\")))\nstatic inline void encode8_3byte_v2(__m128i v, uint8_t *out) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7\n __m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7\n\n const __m128i idxAB_lo = _mm_setr_epi8(0,8,(char)0x80, 1,9,(char)0x80, 2,10,(char)0x80, 3,11,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m128i idxC_lo = _mm_setr_epi8((char)0x80,(char)0x80,0, (char)0x80,(char)0x80,1, (char)0x80,(char)0x80,2, (char)0x80,(char)0x80,3, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m128i idxAB_hi = _mm_setr_epi8(4,12,(char)0x80, 5,13,(char)0x80, 6,14,(char)0x80, 7,15,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m128i idxC_hi = _mm_setr_epi8((char)0x80,(char)0x80,4, (char)0x80,(char)0x80,5, (char)0x80,(char)0x80,6, (char)0x80,(char)0x80,7, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n\n __m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));\n __m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), lo4);\n _mm_storeu_si128((__m128i *)(out + 12), hi4);\n}\n\nint main(void) {\n srand(42);\n int bad=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[8];\n for (int i=0;i<8;i++) {\n int r = rand()%2;\n if (r==0) units[i] = 0x800 + rand()%(0xD800-0x800);\n else units[i] = 0xE000 + rand()%(0x10000-0xE000);\n }\n __m128i v = _mm_loadu_si128((const __m128i*)units);\n uint8_t out[24];\n encode8_3byte_v2(v, out);\n uint8_t expect[24];\n for (int i=0;i<8;i++) {\n uint32_t c = units[i];\n expect[3*i+0] = (uint8_t)(0xE0 | (c>>12));\n expect[3*i+1] = (uint8_t)(0x80 | ((c>>6)&0x3F));\n expect[3*i+2] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect, out, 24)!=0) { bad++; }\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/cjkvec3 /tmp/cjkvec3.c && /tmp/cjkvec3"}
tool result
bad=0
--- Command finished with exit code: 0 ---
assistant
This avoids the shift+repack step (fewer instructions: no srli_si128 + extra packus). Let's replace encode8_3byte with this simpler version.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": "// Vectorized encode of 8 code units, all known to be in the \"3-byte\" range\n// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two\n// 12-byte groups).\n__attribute__((target(\"ssse3\")))\nstatic inline void encode8_3byte(__m128i v, uint8_t *out) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7\n __m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)\n\n const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,\n (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2,\n (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,\n (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80,\n (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,\n (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6,\n (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n\n __m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));\n __m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), lo4);\n _mm_storeu_si128((__m128i *)(out + 12), hi4);\n}", "old_string": "// Vectorized encode of 8 code units, all known to be in the \"3-byte\" range\n// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two\n// 12-byte groups).\n__attribute__((target(\"ssse3\")))\nstatic inline void encode8_3byte(__m128i v, uint8_t *out) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3\n __m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)\n\n const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (
... [1319 characters truncated for page size]
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
21- __m128i AB = _mm_packus_epi16(hi, mid); // low64: hi0..3, high64: mid0..3
22- __m128i C = _mm_packus_epi16(lo, lo); // low64: lo0..3, high64: lo0..3 (dup)
21+ __m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
22+ __m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
24- const __m128i idxAB = _mm_setr_epi8((char)0, (char)8, (char)0x80,
25- (char)1, (char)9, (char)0x80,
26- (char)2, (char)10, (char)0x80,
27- (char)3, (char)11, (char)0x80,
28- (char)0x80, (char)0x80, (char)0x80, (char)0x80);
29- const __m128i idxC = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
30- (char)0x80, (char)0x80, (char)1,
31- (char)0x80, (char)0x80, (char)2,
32- (char)0x80, (char)0x80, (char)3,
33- (char)0x80, (char)0x80, (char)0x80, (char)0x80);
35- __m128i rAB = _mm_shuffle_epi8(AB, idxAB);
36- __m128i rC = _mm_shuffle_epi8(C, idxC);
37- __m128i lo4 = _mm_or_si128(rAB, rC); // bytes for units 0..3, 12 bytes valid
24+ const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
25+ (char)1, (char)9, (char)0x80,
26+ (char)2, (char)10, (char)0x80,
27+ (char)3, (char)11, (char)0x80,
28+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
29+ const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
30+ (char)0x80, (char)0x80, (char)1,
31+ (char)0x80, (char)0x80, (char)2,
32+ (char)0x80, (char)0x80, (char)3,
33+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
34+ const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
35+ (char)5, (char)13, (char)0x80,
36+ (char)6, (char)14, (char)0x80,
37+ (char)7, (char)15, (char)0x80,
38+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
39+ const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
40+ (char)0x80, (char)0x80, (char)5,
41+ (char)0x80, (char)0x80, (char)6,
42+ (char)0x80, (char)0x80, (char)7,
43+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
39- // For units 4..7: hi/mid high 64 bits hold units 4..7 already (from packus
40- // second operand ordering: AB high64 = mid0..3, not hi4..7). We need a
41- // second pack using the upper halves.
42- __m128i hi2 = _mm_srli_si128(hi, 8); // shift so hi4..7 occupy low 64
43- __m128i mid2 = _mm_srli_si128(mid, 8);
44- __m128i lo2 = _mm_srli_si128(lo, 8);
45- __m128i AB2 = _mm_packus_epi16(hi2, mid2);
46- __m128i C2 = _mm_packus_epi16(lo2, lo2);
47- __m128i rAB2 = _mm_shuffle_epi8(AB2, idxAB);
48- __m128i rC2 = _mm_shuffle_epi8(C2, idxC);
49- __m128i hi4 = _mm_or_si128(rAB2, rC2);
45+ __m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
46+ __m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
Context after edit (lines 6-53):
6│
7│ #define INVALID ((size_t)-1)
8│
9│ // Vectorized encode of 8 code units, all known to be in the "3-byte" range
10│ // (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
11│ // 12-byte groups).
12│ __attribute__((target("ssse3")))
13│ static inline void encode8_3byte(__m128i v, uint8_t *out) {
14│ __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
15│ hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
16│ __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
17│ mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
18│ __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
19│ lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
20│
21│ __m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
22│ __m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
23│
24│ const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
25│ (char)1, (char)9, (char)0x80,
26│ (char)2, (char)10, (char)0x80,
27│ (char)3, (char)11, (char)0x80,
28│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
29│ const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
30│ (char)0x80, (char)0x80, (char)1,
31│ (char)0x80, (char)0x80, (char)2,
32│ (char)0x80, (char)0x80, (char)3,
33│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
34│ const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
35│ (char)5, (char)13, (char)0x80,
36│ (char)6, (char)14, (char)0x80,
37│ (char)7, (char)15, (char)0x80,
38│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
39│ const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
40│ (char)0x80, (char)0x80, (char)5,
41│ (char)0x80, (char)0x80, (char)6,
42│ (char)0x80, (char)0x80, (char)7,
43│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
44│
45│ __m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
46│ __m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
47│
48│ _mm_storeu_si128((__m128i *)(out + 0), lo4);
49│ _mm_storeu_si128((__m128i *)(out + 12), hi4);
50│ }
51│
52│ // True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
53│ static inline int all_3byte(__m128i v) {
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
34311483
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 34,311,457 instructions (given: 78,181,481)
SCORE +1.1881 (2.279x)
--- Command finished with exit code: 0 ---
assistant
Let's now try widening to AVX2 (32-byte loads = 16 units at once) to halve loop overhead further.
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | wc -l"}
tool result
230
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/asciiavx.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_ascii16(__m256i v) {\n __m256i hi = _mm256_and_si256(v, _mm256_set1_epi16((short)0xFF80));\n return _mm256_testz_si256(hi, hi);\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline __m128i pack_ascii16(__m256i v) {\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n return _mm_packus_epi16(lo, hi);\n}\n\nint main(void) {\n srand(1);\n int bad=0;\n for (int t=0;t<100000;t++) {\n uint16_t units[16];\n for (int i=0;i<16;i++) units[i] = rand()%0x80;\n __m256i v = _mm256_loadu_si256((const __m256i*)units);\n if (!all_ascii16(v)) { bad++; continue; }\n __m128i r = pack_ascii16(v);\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, r);\n for (int i=0;i<16;i++) if (out[i]!=units[i]) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/asciiavx /tmp/asciiavx.c && /tmp/asciiavx"}
tool result
/tmp/asciiavx.c: In function ‘main’:
/tmp/asciiavx.c:27:17: warning: AVX vector return without AVX enabled changes the ABI [-Wpsabi]
27 | __m256i v = _mm256_loadu_si256((const __m256i*)units);
| ^
In file included from /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/immintrin.h:43,
from /tmp/asciiavx.c:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:871:1: error: inlining failed in call to ‘always_inline’ ‘_mm256_loadu_si256’: target specific option mismatch
871 | _mm256_loadu_si256 (__m256i_u const *__P)
| ^~~~~~~~~~~~~~~~~~
/tmp/asciiavx.c:27:21: note: called from here
27 | __m256i v = _mm256_loadu_si256((const __m256i*)units);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--- Command finished with exit code: 1 ---
Exit code: 1
tool call: bash
{"command": "sed -i '13i __attribute__((target(\"avx2\")))' /tmp/asciiavx.c\ncc -O2 -std=c17 -o /tmp/asciiavx /tmp/asciiavx.c 2>&1 | head -20\n/tmp/asciiavx"}
tool result
/tmp/asciiavx.c: In function ‘main’:
/tmp/asciiavx.c:28:17: warning: AVX vector return without AVX enabled changes the ABI [-Wpsabi]
28 | __m256i v = _mm256_loadu_si256((const __m256i*)units);
| ^
In file included from /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/immintrin.h:43,
from /tmp/asciiavx.c:4:
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:871:1: error: inlining failed in call to ‘always_inline’ ‘_mm256_loadu_si256’: target specific option mismatch
871 | _mm256_loadu_si256 (__m256i_u const *__P)
| ^~~~~~~~~~~~~~~~~~
/tmp/asciiavx.c:28:21: note: called from here
28 | __m256i v = _mm256_loadu_si256((const __m256i*)units);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bash: line 3: /tmp/asciiavx: No such file or directory
--- Command finished with exit code: 127 ---
Exit code: 127
assistant
Need to wrap main's loop body calling avx2 intrinsics in a target-tagged function too, since `main` itself is baseline. Let's just add target to main for this test, but for solve.c we'd add target to utf16_to_utf8 itself.
tool call: bash
{"command": "sed -i 's/int main(void) {/__attribute__((target(\"avx2\")))\\nint main(void) {/' /tmp/asciiavx.c\ncc -O2 -std=c17 -o /tmp/asciiavx /tmp/asciiavx.c 2>&1 | head -20\n/tmp/asciiavx"}
tool result
bad=0
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /proc/cpuinfo | grep -m1 flags | tr ' ' '\\n' | grep -E \"^(sse|avx|bmi)\" "}
tool result
sse
sse2
sse4_1
sse4_2
avx
sse4a
bmi1
avx2
bmi2
avx512f
avx512dq
avx512cd
avx512bw
avx512vl
avx512vbmi
avx512_vbmi2
avx512_vnni
avx512_bitalg
avx512_vpopcntdq
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/avx2_3byte_test.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// encode 16 units (all 3-byte range) -> 48 bytes using two 8-unit SSSE3-style ops within AVX2 lanes\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_3byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));\n __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));\n mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n\n __m256i AB = _mm256_packus_epi16(hi, mid); // per 128-lane: hi0..7,mid0..7 (lane-local)\n __m256i C = _mm256_packus_epi16(lo, lo);\n\n const __m256i idxAB_lo = _mm256_setr_epi8(\n 0,8,(char)0x80, 1,9,(char)0x80, 2,10,(char)0x80, 3,11,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80,\n 0,8,(char)0x80, 1,9,(char)0x80, 2,10,(char)0x80, 3,11,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m256i idxC_lo = _mm256_setr_epi8(\n (char)0x80,(char)0x80,0, (char)0x80,(char)0x80,1, (char)0x80,(char)0x80,2, (char)0x80,(char)0x80,3, (char)0x80,(char)0x80,(char)0x80,(char)0x80,\n (char)0x80,(char)0x80,0, (char)0x80,(char)0x80,1, (char)0x80,(char)0x80,2, (char)0x80,(char)0x80,3, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m256i idxAB_hi = _mm256_setr_epi8(\n 4,12,(char)0x80, 5,13,(char)0x80, 6,14,(char)0x80, 7,15,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80,\n 4,12,(char)0x80, 5,13,(char)0x80, 6,14,(char)0x80, 7,15,(char)0x80, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n const __m256i idxC_hi = _mm256_setr_epi8(\n (char)0x80,(char)0x80,4, (char)0x80,(char)0x80,5, (char)0x80,(char)0x80,6, (char)0x80,(char)0x80,7, (char)0x80,(char)0x80,(char)0x80,(char)0x80,\n (char)0x80,(char)0x80,4, (char)0x80,(char)0x80,5, (char)0x80,(char)0x80,6, (char)0x80,(char)0x80,7, (char)0x80,(char)0x80,(char)0x80,(char)0x80);\n\n __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo)); // lane0: units0-3, lane1: units8-11\n __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi)); // lane0: units4-7, lane1: units12-15\n\n // lo4 lane0 = bytes for units 0-3 (12 bytes), lane1 = bytes for units 8-11 (12 bytes)\n // hi4 lane0 = bytes for units 4-7, lane1 = units 12-15\n __m128i lo4_0 = _mm256_castsi256_si128(lo4); // units 0-3\n __m128i lo4_1 = _mm256_extracti128_si256(lo4, 1); // units 8-11\n __m128i hi4_0 = _mm256_castsi256_si128(hi4); // units 4-7\n __m128i hi4_1 = _mm256_extracti128_si256(hi4, 1); // units 12-15\n\n _mm_storeu_si128((__m128i*)(out+0), lo4_0);\n _mm_storeu_si128((__m128i*)(out+12), hi4_0);\n _mm_storeu_si128((__m128i*)(out+24), lo4_1);\n _mm_storeu_si128((__m128i*)(out+36), hi4_1);\n}\n\n__attribute__((target(\"avx2\")))\nint main(void) {\n srand(5);\n int bad=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[16];\n for (int i=0;i<16;i++) {\n int r = rand()%2;\n if (r==0) units[i] = 0x800 + rand()%(0xD800-0x800);\n else units[i] = 0xE000 + rand()%(0x10000-0xE000);\n }\n __m256i v = _mm256_loadu_si256((const __m256i*)units);\n uint8_t out[48];\n encode16_3byte(v, out);\n uint8_t expect[48];\n for (int i=0;i<16;i++) {\n uint32_t c = units[i];\n expect[3*i+0] = (uint8_t)(0xE0 | (c>>12));\n expect[3*i+1] = (uint8_t)(0x80 | ((c>>6)&0x3F));\n expect[3*i+2] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect, out, 48)!=0) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n re
... [110 characters truncated for page size]
tool result
/tmp/avx2_3byte_test.c: In function ‘main’:
/tmp/avx2_3byte_test.c:47:5: warning: writing 16 bytes into a region of size 12 [-Wstringop-overflow=]
47 | _mm_storeu_si128((__m128i*)(out+36), hi4_1);
| ^
/tmp/avx2_3byte_test.c:62:17: note: at offset 36 into destination object ‘out’ of size 48
62 | uint8_t out[48];
| ^~~
bad=0
--- Command finished with exit code: 0 ---
assistant
Let's build the full AVX2 version, testing correctness carefully. This is a fair bit of work but should give more speedup. Let's do it methodically.
tool call: bash
{"command": "cat > /tmp/avx2_2byte_test.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_2byte16(__m256i v) {\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16(0x0080));\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i inrange = _mm256_cmpgt_epi16(_mm256_xor_si256(_mm256_set1_epi16((short)(0x0780^0x8000)), sbit), _mm256_xor_si256(shifted, sbit));\n return _mm256_movemask_epi8(inrange) == -1;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_2byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_srli_epi16(v, 6);\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00C0));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n __m256i hib = _mm256_packus_epi16(hi, hi); // lane-local: hib bytes 0-7 = hi0-7(lane0), 8-15 dup\n __m256i lob = _mm256_packus_epi16(lo, lo);\n __m256i inter = _mm256_unpacklo_epi8(hib, lob); // lane0: h0 l0 h1 l1...h7 l7 (16 bytes, units0-7)\n // lane1 similarly for units 8-15\n __m128i lane0 = _mm256_castsi256_si128(inter);\n __m128i lane1 = _mm256_extracti128_si256(inter, 1);\n _mm_storeu_si128((__m128i*)(out+0), lane0);\n _mm_storeu_si128((__m128i*)(out+16), lane1);\n}\n\n__attribute__((target(\"avx2\")))\nint main(void) {\n srand(2);\n int bad=0, badenc=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[16];\n for (int i=0;i<16;i++) units[i] = 0x80 + rand()%(0x800-0x80);\n __m256i v = _mm256_loadu_si256((const __m256i*)units);\n if (!all_2byte16(v)) { bad++; continue; }\n uint8_t out[32];\n encode16_2byte(v, out);\n uint8_t expect[32];\n for (int i=0;i<16;i++) {\n uint32_t c = units[i];\n expect[2*i+0] = (uint8_t)(0xC0 | (c>>6));\n expect[2*i+1] = (uint8_t)(0x80 | (c&0x3F));\n }\n if (memcmp(expect,out,32)!=0) badenc++;\n }\n printf(\"bad=%d badenc=%d\\n\", bad, badenc);\n return bad!=0 || badenc!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/avx2_2byte_test /tmp/avx2_2byte_test.c 2>&1 | grep -v Wpsabi\n/tmp/avx2_2byte_test"}
tool result
bad=0 badenc=0
--- Command finished with exit code: 0 ---
assistant
Now the surrogate pairs for AVX2 (8 pairs = 16 units at once):
tool call: bash
{"command": "cat > /tmp/avx2_pair_test.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n// v: 16x16bit units as 8 packed 32-bit lanes: (hi | lo<<16)\n__attribute__((target(\"avx2\")))\nstatic inline int all_surrogate_pairs8(__m256i v) {\n __m256i sbit32 = _mm256_set1_epi32((int)0x80000000u);\n __m256i himask = _mm256_set1_epi32(0xFFFF);\n __m256i hi = _mm256_and_si256(v, himask);\n __m256i lo = _mm256_srli_epi32(v, 16);\n __m256i hi_adj = _mm256_sub_epi32(hi, _mm256_set1_epi32(0xD800));\n __m256i lo_adj = _mm256_sub_epi32(lo, _mm256_set1_epi32(0xDC00));\n __m256i hi_ok = _mm256_cmpgt_epi32(_mm256_xor_si256(_mm256_set1_epi32((int)(0x400u^0x80000000u)), sbit32), _mm256_xor_si256(hi_adj, sbit32));\n __m256i lo_ok = _mm256_cmpgt_epi32(_mm256_xor_si256(_mm256_set1_epi32((int)(0x400u^0x80000000u)), sbit32), _mm256_xor_si256(lo_adj, sbit32));\n __m256i allok = _mm256_and_si256(hi_ok, lo_ok);\n return _mm256_movemask_epi8(allok) == -1;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline __m256i encode8_pairs(__m256i v) {\n __m256i himask = _mm256_set1_epi32(0xFFFF);\n __m256i hi = _mm256_and_si256(v, himask);\n __m256i lo = _mm256_srli_epi32(v, 16);\n __m256i hi_adj = _mm256_sub_epi32(hi, _mm256_set1_epi32(0xD800));\n __m256i lo_adj = _mm256_sub_epi32(lo, _mm256_set1_epi32(0xDC00));\n __m256i cp = _mm256_add_epi32(_mm256_add_epi32(_mm256_slli_epi32(hi_adj, 10), lo_adj), _mm256_set1_epi32(0x10000));\n\n __m256i b0 = _mm256_srli_epi32(cp, 18);\n __m256i b1 = _mm256_and_si256(_mm256_srli_epi32(cp, 12), _mm256_set1_epi32(0x3F));\n __m256i b2 = _mm256_and_si256(_mm256_srli_epi32(cp, 6), _mm256_set1_epi32(0x3F));\n __m256i b3 = _mm256_and_si256(cp, _mm256_set1_epi32(0x3F));\n\n __m256i word = _mm256_set1_epi32((int)0x808080F0u);\n word = _mm256_or_si256(word, b0);\n word = _mm256_or_si256(word, _mm256_slli_epi32(b1, 8));\n word = _mm256_or_si256(word, _mm256_slli_epi32(b2, 16));\n word = _mm256_or_si256(word, _mm256_slli_epi32(b3, 24));\n return word;\n}\n\n__attribute__((target(\"avx2\")))\nint main(void) {\n srand(9);\n int bad=0, badenc=0;\n for (int t=0;t<200000;t++) {\n uint16_t units[16];\n uint32_t cps[8];\n for (int i=0;i<8;i++) {\n uint32_t cp = 0x10000 + rand()%(0x110000-0x10000);\n cps[i]=cp;\n uint32_t cpp = cp - 0x10000;\n units[2*i] = 0xD800+(cpp>>10);\n units[2*i+1] = 0xDC00+(cpp&0x3FF);\n }\n __m256i v = _mm256_loadu_si256((const __m256i*)units);\n if (!all_surrogate_pairs8(v)) { bad++; continue; }\n __m256i r = encode8_pairs(v);\n uint8_t out[32];\n _mm256_storeu_si256((__m256i*)out, r);\n uint8_t expect[32];\n for (int i=0;i<8;i++) {\n uint32_t cp = cps[i];\n expect[4*i+0] = (uint8_t)(0xF0|(cp>>18));\n expect[4*i+1] = (uint8_t)(0x80|((cp>>12)&0x3F));\n expect[4*i+2] = (uint8_t)(0x80|((cp>>6)&0x3F));\n expect[4*i+3] = (uint8_t)(0x80|(cp&0x3F));\n }\n if (memcmp(expect,out,32)!=0) badenc++;\n }\n printf(\"bad=%d badenc=%d\\n\", bad, badenc);\n return bad!=0 || badenc!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/avx2_pair_test /tmp/avx2_pair_test.c 2>&1 | grep -v Wpsabi\n/tmp/avx2_pair_test"}
tool result
bad=0 badenc=0
--- Command finished with exit code: 0 ---
assistant
All AVX2 kernels validated. Now integrate into solve.c, using runtime CPU dispatch since AVX2 isn't guaranteed on all machines (need `__builtin_cpu_supports` to keep correctness gate safe, but the grading machine has AVX2 per earlier check). Let's check if we can just use target attribute per-function without ifunc, applied on whole file build with -O2 (no -mavx2 flag) — should work via target attributes only.
tool call: bash
{"command": "cat > /tmp/asciitest2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);\nint main(void){ return 0; }\nEOF\necho ok"}
tool result
ok
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#define INVALID ((size_t)-1)
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
__m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
(char)1, (char)9, (char)0x80,
(char)2, (char)10, (char)0x80,
(char)3, (char)11, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
(char)0x80, (char)0x80, (char)1,
(char)0x80, (char)0x80, (char)2,
(char)0x80, (char)0x80, (char)3,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
(char)5, (char)13, (char)0x80,
(char)6, (char)14, (char)0x80,
(char)7, (char)15, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
(char)0x80, (char)0x80, (char)5,
(char)0x80, (char)0x80, (char)6,
(char)0x80, (char)0x80, (char)7,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
__m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
__m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
_mm_storeu_si128((__m128i *)(out + 0), lo4);
_mm_storeu_si128((__m128i *)(out + 12), hi4);
}
// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
static inline int all_3byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
__m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i bad = _mm_or_si128(lomask, surrmask);
return _mm_movemask_epi8(bad) == 0;
}
// True iff all 8 code units in v are in [0x0080,0x07FF].
static inline int all_2byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
__m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x0780 ^ 0x8000)));
return _mm_movemask_epi8(inrange) == 0xFFFF;
}
// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
// 16 bytes of UTF-8.
__attribute__((target("ssse3")))
static inline __m128i encode8_2byte(__m128i v) {
__m128i hi = _mm_srli_epi16(v, 6);
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i hib = _mm_packus_epi16(hi, hi);
__m128i lob = _mm_packus_epi16(lo, lo);
return _mm_unpacklo_epi8(hib, lob);
}
// v holds 4 packed 32-bit lanes, each (hi<<0)|(lo<<16) i.e. loaded from 4
// consecutive (high,low) surrogate pairs. True iff all 4 pairs are valid
// (hi in [0xD800,0xDBFF], lo in [0xDC00,0xDFFF]).
static inline int all_surrogate_pairs(__m128i v) {
__m128i sbit32 = _mm_set1_epi32((int)0x80000000u);
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
__m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
__m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i allok = _mm_and_si128(hi_ok, lo_ok);
return _mm_movemask_epi8(allok) == 0xFFFF;
}
// Vectorized encode of 4 valid surrogate pairs (packed as in
// all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).
static inline __m128i encode4_pairs(__m128i v) {
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
__m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
__m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj),
_mm_set1_epi32(0x10000));
__m128i b0 = _mm_srli_epi32(cp, 18);
__m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));
__m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));
__m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));
__m128i word = _mm_set1_epi32((int)0x808080F0u);
word = _mm_or_si128(word, b0);
word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
return word;
}
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
}
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
(void)lo;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
} else if (ip < end && c >= 0xDC00 && c < 0xE000) {
return INVALID;
}
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
assistant
Let's save this as v_ssse3 backup, then build the AVX2 version.
tool call: bash
{"command": "cp /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c /tmp/solve_ssse3_backup.c"}
tool result
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | grep -c \"call.*encode8_3byte\\|call.*encode8_2byte\\|call.*encode4_pairs\\|call.*all_3byte\\|call.*all_2byte\\|call.*all_surrogate\""}
tool result
2
--- Command finished with exit code: 0 ---
assistant
Good, mostly inlined. Now let's write the AVX2 version. I'll check whether runtime dispatch is needed, since the grading corpus is measured on this same machine which supports AVX2.
tool call: bash
{"command": "grep -rn \"march\\|mtune\\|target\" /opt/jcode-bench/harness/grade.py"}
tool result
--- Command finished with exit code: 1 ---
Exit code: 1
tool call: bash
{"command": "cat > /tmp/inlinetest.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n__attribute__((target(\"avx2\")))\nstatic inline __m256i foo(__m256i x) { return _mm256_add_epi16(x,x); }\n\nint bar(const uint16_t *p) {\n __m256i v = ((void)0, *(__m256i*)0); // dummy just to check compile without avx2 target on bar\n return 0;\n}\nEOF\ncc -O2 -std=c17 -c /tmp/inlinetest.c -o /tmp/inlinetest.o 2>&1"}
tool result
--- Command finished with exit code: 0 ---
tool call: write
{"content": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n\n#define INVALID ((size_t)-1)\n\n// ---------------------------------------------------------------------\n// AVX2 kernels (16 code units per iteration).\n// ---------------------------------------------------------------------\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_ascii16(__m256i v) {\n __m256i hi = _mm256_and_si256(v, _mm256_set1_epi16((short)0xFF80));\n return _mm256_testz_si256(hi, hi);\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline __m128i pack_ascii16(__m256i v) {\n __m128i lo = _mm256_castsi256_si128(v);\n __m128i hi = _mm256_extracti128_si256(v, 1);\n return _mm_packus_epi16(lo, hi);\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_2byte16(__m256i v) {\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16(0x0080));\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i inrange = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x0780 ^ 0x8000)), sbit),\n _mm256_xor_si256(shifted, sbit));\n return _mm256_movemask_epi8(inrange) == -1;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_2byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_srli_epi16(v, 6);\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00C0));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n __m256i hib = _mm256_packus_epi16(hi, hi);\n __m256i lob = _mm256_packus_epi16(lo, lo);\n __m256i inter = _mm256_unpacklo_epi8(hib, lob);\n __m128i lane0 = _mm256_castsi256_si128(inter);\n __m128i lane1 = _mm256_extracti128_si256(inter, 1);\n _mm_storeu_si128((__m128i *)(out + 0), lane0);\n _mm_storeu_si128((__m128i *)(out + 16), lane1);\n}\n\n// True iff all 16 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\n__attribute__((target(\"avx2\")))\nstatic inline int all_3byte16(__m256i v) {\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i lomask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(v, sbit));\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));\n __m256i surrmask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(shifted, sbit));\n // lomask currently true when shifted-from-zero c < 0x800 (i.e. NOT >= 0x800):\n // cmpgt(0x800, c) true iff c < 0x800 -> that is the \"bad\" (too-low) case.\n __m256i bad = _mm256_or_si256(lomask, surrmask);\n return _mm256_movemask_epi8(bad) == 0;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_3byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));\n __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));\n mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n\n __m256i AB = _mm256_packus_epi16(hi, mid);\n __m256i C = _mm256_packus_epi16(lo, lo);\n\n const __m256i idxAB_lo = _mm256_setr_epi8(\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_lo = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (ch
... [19712 characters truncated for page size]
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (528 lines):
4- #include <emmintrin.h>
5- #include <tmmintrin.h>
4+ #include <immintrin.h>
9- // Vectorized encode of 8 code units, all known to be in the "3-byte" range
10- // (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
11- // 12-byte groups).
8+ // ---------------------------------------------------------------------
9+ // AVX2 kernels (16 code units per iteration).
10+ // ---------------------------------------------------------------------
12+ __attribute__((target("avx2")))
13+ static inline int all_ascii16(__m256i v) {
14+ __m256i hi = _mm256_and_si256(v, _mm256_set1_epi16((short)0xFF80));
15+ return _mm256_testz_si256(hi, hi);
16+ }
18+ __attribute__((target("avx2")))
19+ static inline __m128i pack_ascii16(__m256i v) {
20+ __m128i lo = _mm256_castsi256_si128(v);
21+ __m128i hi = _mm256_extracti128_si256(v, 1);
22+ return _mm_packus_epi16(lo, hi);
23+ }
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -40"}
tool result
45276604
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -20"}
tool result
build 1.6s
verify 1.9s PASS
measure 0.5s 45,276,604 instructions (given: 78,181,481)
SCORE +0.7881 (1.727x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (avx2) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgavx_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgavx_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (avx2) ==
887697
== latin (avx2) ==
10297750
== cjk (avx2) ==
20388713
== emoji (avx2) ==
12824704
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | sed -n '/<utf16_to_utf8>:/,/ret/p' | head -30"}
tool result
0000000000003150 <utf16_to_utf8>:
3150: 8b 05 02 2f 00 00 mov eax,DWORD PTR [rip+0x2f02] # 6058 <level.0>
3156: 49 89 d0 mov r8,rdx
3159: 85 c0 test eax,eax
315b: 0f 88 6f 01 00 00 js 32d0 <utf16_to_utf8+0x180>
3161: 83 f8 02 cmp eax,0x2
3164: 0f 84 7f 01 00 00 je 32e9 <utf16_to_utf8+0x199>
316a: 83 f8 01 cmp eax,0x1
316d: 0f 84 97 01 00 00 je 330a <utf16_to_utf8+0x1ba>
3173: 4c 8d 0c 77 lea r9,[rdi+rsi*2]
3177: 4c 89 c0 mov rax,r8
317a: 4c 39 cf cmp rdi,r9
317d: 72 30 jb 31af <utf16_to_utf8+0x5f>
317f: e9 dc 07 00 00 jmp 3960 <utf16_to_utf8+0x810>
3184: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0]
318a: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
3191: 00 00 00 00
3195: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
319c: 00 00 00 00
31a0: 88 10 mov BYTE PTR [rax],dl
31a2: 48 83 c7 02 add rdi,0x2
31a6: 48 83 c0 01 add rax,0x1
31aa: 4c 39 cf cmp rdi,r9
31ad: 73 54 jae 3203 <utf16_to_utf8+0xb3>
31af: 0f b7 17 movzx edx,WORD PTR [rdi]
31b2: 66 83 fa 7f cmp dx,0x7f
31b6: 76 e8 jbe 31a0 <utf16_to_utf8+0x50>
31b8: 8d 8a 00 28 ff ff lea ecx,[rdx-0xd800]
31be: 81 fa ff 07 00 00 cmp edx,0x7ff
31c4: 76 4a jbe 3210 <utf16_to_utf8+0xc0>
--- Command finished with exit code: 0 ---
assistant
AVX2 version scored lower than SSSE3-only version. Let's investigate before deciding.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\ncc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c /tmp/asciitest.c -o /tmp/cjktest_avx 2>&1 | tail -5\ncat > /tmp/cjktest2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <stdlib.h>\nsize_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out);\nint main(void) {\n size_t n = 200000;\n uint16_t *in = malloc(n*2);\n uint8_t *out = malloc(n*3+16);\n for (size_t i=0;i<n;i++) in[i] = 0x4E00 + (i%0x5FF);\n size_t r = utf16_to_utf8(in, n, out);\n return (int)(r & 0xff);\n}\nEOF\ncc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c /tmp/cjktest2.c -o /tmp/cjktest_avx\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_cjkmini_avx.out /tmp/cjktest_avx >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_cjkmini_avx.out | awk '{s+=$2} END{print s}'"}
tool result
20000360
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\ncc -O2 -std=c17 -fno-lto -g -I /tmp /tmp/solve_ssse3_backup.c /tmp/cjktest2.c -o /tmp/cjktest_ssse3\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_cjkmini_ssse3.out /tmp/cjktest_ssse3 >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_cjkmini_ssse3.out | awk '{s+=$2} END{print s}'"}
tool result
7525206
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/cjktest_avx -M intel | sed -n '/<utf16_to_utf8_avx2>:/,/^0000/p' | wc -l\nobjdump -d /tmp/cjktest_avx -M intel | sed -n '/<utf16_to_utf8_avx2>:/,/^0000/p' | head -150"}
tool result
400
0000000000002740 <utf16_to_utf8_avx2>:
2740: 48 89 f9 mov rcx,rdi
2743: 48 8d 3c 77 lea rdi,[rdi+rsi*2]
2747: 48 89 d6 mov rsi,rdx
274a: 48 39 f9 cmp rcx,rdi
274d: 0f 83 95 06 00 00 jae 2de8 <utf16_to_utf8_avx2+0x6a8>
2753: c5 d5 76 ed vpcmpeqd ymm5,ymm5,ymm5
2757: c5 7d 6f 2d c1 18 00 vmovdqa ymm13,YMMWORD PTR [rip+0x18c1] # 4020 <_IO_stdin_used+0x20>
275e: 00
275f: 48 89 d0 mov rax,rdx
2762: c5 7d 6f 25 d6 18 00 vmovdqa ymm12,YMMWORD PTR [rip+0x18d6] # 4040 <_IO_stdin_used+0x40>
2769: 00
276a: c5 7d 6f 1d ee 18 00 vmovdqa ymm11,YMMWORD PTR [rip+0x18ee] # 4060 <_IO_stdin_used+0x60>
2771: 00
2772: c5 b5 72 d5 10 vpsrld ymm9,ymm5,0x10
2777: 66 0f 1f 84 00 00 00 nop WORD PTR [rax+rax*1+0x0]
277e: 00 00
2780: 0f b7 11 movzx edx,WORD PTR [rcx]
2783: 83 fa 7f cmp edx,0x7f
2786: 0f 86 04 01 00 00 jbe 2890 <utf16_to_utf8_avx2+0x150>
278c: 41 b8 80 00 80 00 mov r8d,0x800080
2792: c4 c1 79 6e d0 vmovd xmm2,r8d
2797: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
279e: c4 e2 7d 58 d2 vpbroadcastd ymm2,xmm2
27a3: 41 81 f8 ff 07 00 00 cmp r8d,0x7ff
27aa: 0f 86 20 02 00 00 jbe 29d0 <utf16_to_utf8_avx2+0x290>
27b0: 81 fa ff 07 00 00 cmp edx,0x7ff
27b6: 0f 87 54 04 00 00 ja 2c10 <utf16_to_utf8_avx2+0x4d0>
27bc: 48 8d 51 20 lea rdx,[rcx+0x20]
27c0: 48 39 d7 cmp rdi,rdx
27c3: 0f 82 93 00 00 00 jb 285c <utf16_to_utf8_avx2+0x11c>
27c9: b9 80 07 80 07 mov ecx,0x7800780
27ce: c5 e5 76 db vpcmpeqd ymm3,ymm3,ymm3
27d2: c5 bd 71 f3 07 vpsllw ymm8,ymm3,0x7
27d7: c5 c5 71 f3 0f vpsllw ymm7,ymm3,0xf
27dc: c5 f9 6e e1 vmovd xmm4,ecx
27e0: b9 c0 00 c0 00 mov ecx,0xc000c0
27e5: c5 f9 6e f1 vmovd xmm6,ecx
27e9: c5 e5 71 d3 0a vpsrlw ymm3,ymm3,0xa
27ee: c4 e2 7d 58 e4 vpbroadcastd ymm4,xmm4
27f3: c4 e2 7d 58 f6 vpbroadcastd ymm6,xmm6
27f8: eb 43 jmp 283d <utf16_to_utf8_avx2+0xfd>
27fa: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0]
2800: c5 f5 71 d0 06 vpsrlw ymm1,ymm0,0x6
2805: c5 fd db c3 vpand ymm0,ymm0,ymm3
2809: 48 8d 4a 20 lea rcx,[rdx+0x20]
280d: 48 83 c0 20 add rax,0x20
2811: c5 f5 eb ce vpor ymm1,ymm1,ymm6
2815: c5 fd eb c2 vpor ymm0,ymm0,ymm2
2819: c5 f5 67 c9 vpackuswb ymm1,ymm1,ymm1
281d: c5 fd 67 c0 vpackuswb ymm0,ymm0,ymm0
2821: c5 f5 60 c0 vpunpcklbw ymm0,ymm1,ymm0
2825: c5 fa 7f 40 e0 vmovdqu XMMWORD PTR [rax-0x20],xmm0
282a: c4 e3 7d 39 40 f0 01 vextracti128 XMMWORD PTR [rax-0x10],ymm0,0x1
2831: 48 39 cf cmp rdi,rcx
2834: 0f 82 76 05 00 00 jb 2db0 <utf16_to_utf8_avx2+0x670>
283a: 48 89 ca mov rdx,rcx
283d: c5 fe 6f 42 e0 vmovdqu ymm0,YMMWORD PTR [rdx-0x20]
2842: c4 c1 7d fd c8 vpaddw ymm1,ymm0,ymm8
2847: c5 f5 ef cf vpxor ymm1,ymm1,ymm7
284b: c5 dd 65 c9 vpcmpgtw ymm1,ymm4,ymm1
284f: c5 fd d7 c9 vpmovmskb ecx,ymm1
2853: 83 f9 ff cmp ecx,0xffffffff
2856: 74 a8 je 2800 <utf16_to_utf8_avx2+0xc0>
2858: 48 8d 4a e0 lea rcx,[rdx-0x20]
285c: 48 39 f9 cmp rcx,rdi
285f: 0f 83 d7 00 00 00 jae 293c <utf16_to_utf8_avx2+0x1fc>
2865: 44 0f b7 01 movzx r8d,WORD PTR [rcx]
2869: 41 8d 50 80 lea edx,[r8-0x80]
286d: 81 fa 7f 07 00 00 cmp edx,0x77f
2873: 0f 86 1c 01 00 00 jbe 2995 <utf16_to_utf8_avx2+0x255>
2879: 0f b7 11 movzx edx,WORD PTR [rcx]
287c: 83 fa 7f cmp edx,0x7f
287f: 0f 87 07 ff ff ff ja 278c <utf16_to_utf8_avx2+0x4c>
2885: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
288c: 00 00 00 00
2890: 4c 8d 41 20 lea r8,[rcx+0x20]
2894: 4c 39 c7 cmp rdi,r8
2897: 0f 82 5c 05 00 00 jb 2df9 <utf16_to_utf8_avx2+0x6b9>
289d: c5 ed 76 d2 vpcmpeqd ymm2,ymm2,ymm2
28a1: c5 ed 71 f2 07 vpsllw ymm2,ymm2,0x7
28a6: eb 3f jmp 28e7 <utf16_to_utf8_avx2+0x1a7>
28a8: 66 90 xchg ax,ax
28aa: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
28b1: 00 00 00 00
28b5: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
28bc: 00 00 00 00
28c0: c5 f9 6f c8 vmovdqa xmm1,xmm0
28c4: c4 e3 7d 39 c0 01 vextracti128 xmm0,ymm0,0x1
28ca: 49 8d 50 20 lea rdx,[r8+0x20]
28ce: 48 83 c0 10 add rax,0x10
28d2: c5 f1 67 c0 vpackuswb xmm0,xmm1,xmm0
28d6: c5 fa 7f 40 f0 vmovdqu XMMWORD PTR [rax-0x10],xmm0
28db: 48 39 d7 cmp rdi,rdx
28de: 0f 82 c4 04 00 00 jb 2da8 <utf16_to_utf8_avx2+0x668>
28e4: 49 89 d0 mov r8,rdx
28e7: c4 c1 7e 6f 40 e0 vmovdqu ymm0,YMMWORD PTR [r8-0x20]
28ed: c4 e2 7d 17 c2 vptest ymm0,ymm2
28f2: 74 cc je 28c0 <utf16_to_utf8_avx2+0x180>
28f4: 49 8d 48 e0 lea rcx,[r8-0x20]
28f8: 48 39 f9 cmp rcx,rdi
28fb: 73 3f jae 293c <utf16_to_utf8_avx2+0x1fc>
28fd: 0f b7 11 movzx edx,WORD PTR [rcx]
2900: 83 fa 7f cmp edx,0x7f
2903: 0f 87 77 fe ff ff ja 2780 <utf16_to_utf8_avx2+0x40>
2909: 48 83 c1 02 add rcx,0x2
290d: 48 83 c0 01 add rax,0x1
2911: 88 50 ff mov BYTE PTR [rax-0x1],dl
2914: 48 39 f9 cmp rcx,rdi
2917: 73 23 jae 293c <utf16_to_utf8_avx2+0x1fc>
2919: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0]
2920: 0f b7 11 movzx edx,WORD PTR [rcx]
2923: 83 fa 7f cmp edx,0x7f
2926: 0f 87 54 fe ff ff ja 2780 <utf16_to_utf8_avx2+0x40>
292c: 48 83 c1 02 add rcx,0x2
2930: 48 83 c0 01 add rax,0x1
2934: 88 50 ff mov BYTE PTR [rax-0x1],dl
2937: 48 39 f9 cmp rcx,rdi
293a: 72 e4 jb 2920 <utf16_to_utf8_avx2+0x1e0>
293c: 48 29 f0 sub rax,rsi
293f: c5 f8 77 vzeroupper
2942: c3 ret
2943: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0]
2949: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
2950: 00 00 00 00
2954: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
295b: 00 00 00 00
295f: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
2966: 00 00 00 00
296a: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
2971: 00 00 00 00
2975: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0]
297c: 00 00 00 00
2980: 44 0f b7 01 movzx r8d,WORD PTR [rcx]
2984: 44 89 c2 mov edx,r8d
2987: 83 c2 80 add edx,0xffffff80
298a: 66 81 fa 7f 07 cmp dx,0x77f
298f: 0f 87 eb fd ff ff ja 2780 <utf16_to_utf8_avx2+0x40>
2995: 44 89 c2 mov edx,r8d
2998: 41 c1 e8 06 shr r8d,0x6
299c: 48 83 c1 02 add rcx,0x2
29a0: 48 83 c0 02 add rax,0x2
29a4: c1 e2 08 shl edx,0x8
29a7: 81 e2 00 3f 00 00 and edx,0x3f00
29ad: 44 09 c2 or edx,r8d
29b0: 81 ca c0 80 00 00 or edx,0x80c0
29b6: 66 89 50 fe mov WORD PTR [rax-0x2],dx
29ba: 48 39 f9 cmp rcx,rdi
29bd: 72 c1 jb 2980 <utf16_to_utf8_avx2+0x240>
29bf: 48 29 f0 sub rax,rsi
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/cjktest_avx -M intel | sed -n '/<utf16_to_utf8_avx2>:/,/^0000/p' | grep -n \"encode16_3byte\\|call\\|vpshufb\" | head -30"}
tool result
309: 2c99: c4 42 7d 00 f5 vpshufb ymm14,ymm0,ymm13
310: 2c9e: c4 c2 7d 00 c3 vpshufb ymm0,ymm0,ymm11
311: 2ca3: c4 42 75 00 d4 vpshufb ymm10,ymm1,ymm12
312: 2ca8: c4 e2 75 00 0d cf 13 vpshufb ymm1,ymm1,YMMWORD PTR [rip+0x13cf] # 4080 <_IO_stdin_used+0x80>
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/cjktest_avx -M intel | sed -n '/2c10:/,/2d[0-9a-f][0-9a-f]:.*jb/p' | head -80"}
tool result
2c10: 4c 8d 41 20 lea r8,[rcx+0x20]
2c14: 4c 39 c7 cmp rdi,r8
2c17: 0f 82 f3 01 00 00 jb 2e10 <utf16_to_utf8_avx2+0x6d0>
2c1d: ba 00 28 00 28 mov edx,0x28002800
2c22: c5 cd 76 f6 vpcmpeqd ymm6,ymm6,ymm6
2c26: c5 f9 6e fa vmovd xmm7,edx
2c2a: c5 dd 71 f6 0f vpsllw ymm4,ymm6,0xf
2c2f: ba 00 08 00 08 mov edx,0x8000800
2c34: c5 f9 6e da vmovd xmm3,edx
2c38: ba e0 00 e0 00 mov edx,0xe000e0
2c3d: c4 e2 7d 58 ff vpbroadcastd ymm7,xmm7
2c42: c5 79 6e c2 vmovd xmm8,edx
2c46: c4 e2 7d 58 db vpbroadcastd ymm3,xmm3
2c4b: c4 42 7d 58 c0 vpbroadcastd ymm8,xmm8
2c50: e9 89 00 00 00 jmp 2cde <utf16_to_utf8_avx2+0x59e>
2c55: 0f 1f 00 nop DWORD PTR [rax]
2c58: c5 8d 71 d6 0a vpsrlw ymm14,ymm6,0xa
2c5d: c5 f5 71 d0 0c vpsrlw ymm1,ymm0,0xc
2c62: 49 8d 50 20 lea rdx,[r8+0x20]
2c66: 48 83 c0 30 add rax,0x30
2c6a: c5 85 71 d0 06 vpsrlw ymm15,ymm0,0x6
2c6f: c5 ad 71 d6 0c vpsrlw ymm10,ymm6,0xc
2c74: c4 c1 7d db c6 vpand ymm0,ymm0,ymm14
2c79: c4 c1 75 db ca vpand ymm1,ymm1,ymm10
2c7e: c4 41 05 db fe vpand ymm15,ymm15,ymm14
2c83: c5 fd eb c2 vpor ymm0,ymm0,ymm2
2c87: c4 c1 75 eb c8 vpor ymm1,ymm1,ymm8
2c8c: c5 05 eb fa vpor ymm15,ymm15,ymm2
2c90: c5 fd 67 c0 vpackuswb ymm0,ymm0,ymm0
2c94: c4 c1 75 67 cf vpackuswb ymm1,ymm1,ymm15
2c99: c4 42 7d 00 f5 vpshufb ymm14,ymm0,ymm13
2c9e: c4 c2 7d 00 c3 vpshufb ymm0,ymm0,ymm11
2ca3: c4 42 75 00 d4 vpshufb ymm10,ymm1,ymm12
2ca8: c4 e2 75 00 0d cf 13 vpshufb ymm1,ymm1,YMMWORD PTR [rip+0x13cf] # 4080 <_IO_stdin_used+0x80>
2caf: 00 00
2cb1: c4 41 2d eb d6 vpor ymm10,ymm10,ymm14
2cb6: c5 f5 eb c8 vpor ymm1,ymm1,ymm0
2cba: c5 7a 7f 50 d0 vmovdqu XMMWORD PTR [rax-0x30],xmm10
2cbf: c5 fa 7f 48 dc vmovdqu XMMWORD PTR [rax-0x24],xmm1
2cc4: c4 63 7d 39 50 e8 01 vextracti128 XMMWORD PTR [rax-0x18],ymm10,0x1
2ccb: c4 e3 7d 39 48 f4 01 vextracti128 XMMWORD PTR [rax-0xc],ymm1,0x1
2cd2: 48 39 d7 cmp rdi,rdx
2cd5: 0f 82 05 01 00 00 jb 2de0 <utf16_to_utf8_avx2+0x6a0>
2cdb: 49 89 d0 mov r8,rdx
2cde: c4 c1 7e 6f 40 e0 vmovdqu ymm0,YMMWORD PTR [r8-0x20]
2ce4: c5 fd fd cf vpaddw ymm1,ymm0,ymm7
2ce8: c5 7d ef d4 vpxor ymm10,ymm0,ymm4
2cec: c5 f5 ef cc vpxor ymm1,ymm1,ymm4
2cf0: c4 41 65 65 d2 vpcmpgtw ymm10,ymm3,ymm10
2cf5: c5 e5 65 c9 vpcmpgtw ymm1,ymm3,ymm1
2cf9: c4 c1 75 eb ca vpor ymm1,ymm1,ymm10
2cfe: c5 fd d7 d1 vpmovmskb edx,ymm1
2d02: 85 d2 test edx,edx
2d04: 0f 84 4e ff ff ff je 2c58 <utf16_to_utf8_avx2+0x518>
2d0a: 49 8d 48 e0 lea rcx,[r8-0x20]
2d0e: 48 39 f9 cmp rcx,rdi
2d11: 0f 83 25 fc ff ff jae 293c <utf16_to_utf8_avx2+0x1fc>
2d17: 0f b7 11 movzx edx,WORD PTR [rcx]
2d1a: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
2d21: 41 81 f8 ff 07 00 00 cmp r8d,0x7ff
2d28: 0f 86 52 fa ff ff jbe 2780 <utf16_to_utf8_avx2+0x40>
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/cpucheck.c << 'EOF'\n#include <stdio.h>\nint main(void) {\n printf(\"avx2=%d ssse3=%d sse2=%d\\n\",\n __builtin_cpu_supports(\"avx2\"),\n __builtin_cpu_supports(\"ssse3\"),\n __builtin_cpu_supports(\"sse2\"));\n return 0;\n}\nEOF\ncc -O2 -o /tmp/cpucheck /tmp/cpucheck.c\n/tmp/cpucheck\necho \"under valgrind:\"\nvalgrind --tool=callgrind --toggle-collect=main --collect-atstart=no /tmp/cpucheck 2>&1 | tail -5"}
tool result
avx2=1024 ssse3=64 sse2=16
under valgrind:
==3410==
==3410== Events : Ir
==3410== Collected : 2618
==3410==
==3410== I refs: 2,618
--- Command finished with exit code: 0 ---
assistant
The AVX2 version regressed due to shorter run lengths in the actual corpus (CJK/emoji bursts are much shorter than 16 units, so the 16-wide vectorized path rarely triggers, wasting setup). Let's revert to SSSE3 and then try a hybrid: AVX2 only for ASCII (which has long runs), SSSE3 (8-wide) for everything else.
tool call: bash
{"command": "cp /tmp/solve_ssse3_backup.c /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c\ncd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 34,311,457 instructions (given: 78,181,481)
SCORE +1.1881 (2.279x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\nrun_lens = {'ascii':[], '2byte':[], '3byte':[], 'pair':[]}\ndef classify(c):\n if c<0x80: return 'ascii'\n if c<0x800: return '2byte'\n if c<0xD800 or c>=0xE000: return '3byte'\n return 'pair'\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c = units[i]\n cls = classify(c)\n if cls=='pair':\n j=i\n while j<len(units) and classify(units[j])=='pair':\n j+=2\n run_lens['pair'].append((j-i)//2)\n i=j\n else:\n j=i\n while j<len(units) and classify(units[j])==cls:\n j+=1\n run_lens[cls].append(j-i)\n i=j\nimport statistics\nfor k,v in run_lens.items():\n if v:\n print(k, 'count',len(v),'mean',statistics.mean(v),'median',statistics.median(v), 'frac>=8', sum(1 for x in v if x>=8)/len(v), 'frac>=16', sum(1 for x in v if x>=16)/len(v))\n\"\n"}
tool result
ascii count 21908 mean 26.397343436187693 median 6.0 frac>=8 0.397662954171992 frac>=16 0.1306372101515428
2byte count 10552 mean 12.96559893858984 median 10.0 frac>=8 0.6724791508718726 frac>=16 0.2916034874905231
3byte count 4166 mean 44.68458953432549 median 33.0 frac>=8 0.9395103216514642 frac>=16 0.7914066250600096
pair count 7084 mean 7.397092038396386 median 5.0 frac>=8 0.3694240542066629 frac>=16 0.0940146809712027
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | grep -n \"encode8_3byte\\|all_3byte\\|} else if (c >= 0x800\""}
tool result
13:static inline void encode8_3byte(__m128i v, uint8_t *out) {
53:static inline int all_3byte(__m128i v) {
154: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
157: if (!all_3byte(v)) break;
158: encode8_3byte(v, op);
--- Command finished with exit code: 0 ---
assistant
3-byte (CJK) runs are the longest (79% >= 16 units). Let's add a 16-wide AVX2 fast path specifically for the 3-byte range, keeping SSSE3 (8-wide) elsewhere.
tool call: bash
{"command": "sed -n '150,175p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
--- Command finished with exit code: 0 ---
assistant
Let's add AVX2 3-byte kernel and use it with a 16-wide loop, falling back to the 8-wide SSSE3 loop for the tail.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "old_string": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <tmmintrin.h>", "new_string": "#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <tmmintrin.h>\n#include <immintrin.h>\n\n// True iff all 16 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\n__attribute__((target(\"avx2\")))\nstatic inline int all_3byte16(__m256i v) {\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i lomask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(v, sbit));\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));\n __m256i surrmask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(shifted, sbit));\n __m256i bad = _mm256_or_si256(lomask, surrmask);\n return _mm256_movemask_epi8(bad) == 0;\n}\n\n// Vectorized encode of 16 code units, all known to be in the \"3-byte\" range,\n// to 48 bytes of UTF-8.\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_3byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));\n __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));\n mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n\n __m256i AB = _mm256_packus_epi16(hi, mid);\n __m256i C = _mm256_packus_epi16(lo, lo);\n\n const __m256i idxAB_lo = _mm256_setr_epi8(\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_lo = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxAB_hi = _mm256_setr_epi8(\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_hi = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n\n __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo));\n __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), _mm256_castsi256_si128(lo4));\n _mm_storeu_si128((__m128i *)(out + 12), _mm256_castsi
... [360 characters truncated for page size]
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
5- #include <tmmintrin.h>
5+ #include <tmmintrin.h>
6+ #include <immintrin.h>
8+ // True iff all 16 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
9+ __attribute__((target("avx2")))
10+ static inline int all_3byte16(__m256i v) {
11+ __m256i sbit = _mm256_set1_epi16((short)0x8000);
12+ __m256i lomask = _mm256_cmpgt_epi16(
13+ _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),
14+ _mm256_xor_si256(v, sbit));
15+ __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));
16+ __m256i surrmask = _mm256_cmpgt_epi16(
17+ _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),
18+ _mm256_xor_si256(shifted, sbit));
19+ __m256i bad = _mm256_or_si256(lomask, surrmask);
20+ return _mm256_movemask_epi8(bad) == 0;
21+ }
23+ // Vectorized encode of 16 code units, all known to be in the "3-byte" range,
24+ // to 48 bytes of UTF-8.
25+ __attribute__((target("avx2")))
26+ static inline void encode16_3byte(__m256i v, uint8_t *out) {
27+ __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));
28+ hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));
29+ __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));
30+ mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));
31+ __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));
32+ lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));
34+ __m256i AB = _mm256_packus_epi16(hi, mid);
35+ __m256i C = _mm256_packus_epi16(lo, lo);
37+ const __m256i idxAB_lo = _mm256_setr_epi8(
38+ (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,
39+ (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,
40+ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
41+ (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,
42+ (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,
43+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
44+ const __m256i idxC_lo = _mm256_setr_epi8(
45+ (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,
46+ (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,
47+ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
48+ (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,
49+ (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,
50+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
51+ const __m256i idxAB_hi = _mm256_setr_epi8(
52+ (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,
53+ (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,
54+ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
55+ (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,
56+ (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,
57+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
58+ const __m256i idxC_hi = _mm256_setr_epi8(
59+ (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,
60+ (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,
61+ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
62+ (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,
63+ (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,
64+ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
66+ __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo));
67+ __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi));
69+ _mm_storeu_si128((__m128i *)(out + 0), _mm256_castsi256_si128(lo4));
70+ _mm_storeu_si128((__m128i *)(out + 12), _mm256_castsi256_si128(hi4));
71+ _mm_storeu_si128((__m128i *)(out + 24), _mm256_extracti128_si256(lo4, 1));
72+ _mm_storeu_si128((__m128i *)(out + 36), _mm256_extracti128_si256(hi4, 1));
73+ }
75+ static int g_have_avx2 = -1;
76+ static inline int have_avx2(void) {
77+ if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports("avx2") ? 1 : 0;
78+ return g_have_avx2;
79+ }
Context after edit (lines 1-82):
1│ #include <stdint.h>
2│ #include <stddef.h>
3│ #include <string.h>
4│ #include <emmintrin.h>
5│ #include <tmmintrin.h>
6│ #include <immintrin.h>
7│
8│ // True iff all 16 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
9│ __attribute__((target("avx2")))
10│ static inline int all_3byte16(__m256i v) {
11│ __m256i sbit = _mm256_set1_epi16((short)0x8000);
12│ __m256i lomask = _mm256_cmpgt_epi16(
13│ _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),
14│ _mm256_xor_si256(v, sbit));
15│ __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));
16│ __m256i surrmask = _mm256_cmpgt_epi16(
17│ _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),
18│ _mm256_xor_si256(shifted, sbit));
19│ __m256i bad = _mm256_or_si256(lomask, surrmask);
20│ return _mm256_movemask_epi8(bad) == 0;
21│ }
22│
23│ // Vectorized encode of 16 code units, all known to be in the "3-byte" range,
24│ // to 48 bytes of UTF-8.
25│ __attribute__((target("avx2")))
26│ static inline void encode16_3byte(__m256i v, uint8_t *out) {
27│ __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));
28│ hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));
29│ __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));
30│ mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));
31│ __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));
32│ lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));
33│
34│ __m256i AB = _mm256_packus_epi16(hi, mid);
35│ __m256i C = _mm256_packus_epi16(lo, lo);
36│
37│ const __m256i idxAB_lo = _mm256_setr_epi8(
38│ (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,
39│ (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,
40│ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
41│ (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,
42│ (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,
43│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
44│ const __m256i idxC_lo = _mm256_setr_epi8(
45│ (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,
46│ (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,
47│ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
48│ (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,
49│ (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,
50│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
51│ const __m256i idxAB_hi = _mm256_setr_epi8(
52│ (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,
53│ (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,
54│ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
55│ (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,
56│ (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,
57│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
58│ const __m256i idxC_hi = _mm256_setr_epi8(
59│ (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,
60│ (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,
61│ (char)0x80, (char)0x80, (char)0x80, (char)0x80,
62│ (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,
63│ (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,
64│ (char)0x80, (char)0x80, (char)0x80, (char)0x80);
65│
66│ __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo));
67│ __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi));
68│
69│ _mm_storeu_si128((__m128i *)(out + 0), _mm256_castsi256_si128(lo4));
70│ _mm_storeu_si128((__m128i *)(out + 12), _mm256_castsi256_si128(hi4));
71│ _mm_storeu_si128((__m128i *)(out + 24), _mm256_extracti128_si256(lo4, 1));
72│ _mm_storeu_si128((__m128i *)(out + 36), _mm256_extracti128_si256(hi4, 1));
73│ }
74│
75│ static int g_have_avx2 = -1;
76│ static inline int have_avx2(void) {
77│ if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports("avx2") ? 1 : 0;
78│ return g_have_avx2;
79│ }
80│
81│ #define INVALID ((size_t)-1)
82│
assistant
Now update the 3-byte branch in the main loop to try the 16-wide AVX2 path first when available.
tool call: bash
{"command": "grep -n \"c >= 0x800 && (c < 0xD800\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
228: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
238: if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '225,248p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n if (have_avx2()) {\n while (ip + 16 <= end) {\n __m256i v = _mm256_loadu_si256((const __m256i *)ip);\n if (!all_3byte16(v)) break;\n encode16_3byte(v, op);\n ip += 16;\n op += 48;\n }\n }\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n if (!all_3byte(v)) break;\n encode8_3byte(v, op);\n ip += 8;\n op += 24;\n }", "old_string": " } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n if (!all_3byte(v)) break;\n encode8_3byte(v, op);\n ip += 8;\n op += 24;\n }"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
229+ if (have_avx2()) {
230+ while (ip + 16 <= end) {
231+ __m256i v = _mm256_loadu_si256((const __m256i *)ip);
232+ if (!all_3byte16(v)) break;
233+ encode16_3byte(v, op);
234+ ip += 16;
235+ op += 48;
236+ }
237+ }
Context after edit (lines 225-247):
225│ ip++;
226│ } while (ip < end && (c = *ip) < 0x80);
227│ }
228│ } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
229│ if (have_avx2()) {
230│ while (ip + 16 <= end) {
231│ __m256i v = _mm256_loadu_si256((const __m256i *)ip);
232│ if (!all_3byte16(v)) break;
233│ encode16_3byte(v, op);
234│ ip += 16;
235│ op += 48;
236│ }
237│ }
238│ while (ip + 8 <= end) {
239│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
240│ if (!all_3byte(v)) break;
241│ encode8_3byte(v, op);
242│ ip += 8;
243│ op += 24;
244│ }
245│ if (ip >= end) break;
246│ c = *ip;
247│ if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
submission/solve.c: In function ‘utf16_to_utf8’:
submission/solve.c:231:29: warning: AVX vector return without AVX enabled changes the ABI [-Wpsabi]
231 | __m256i v = _mm256_loadu_si256((const __m256i *)ip);
| ^
In file included from /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/immintrin.h:43,
from submission/solve.c:6:
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:871:1: error: inlining failed in call to ‘always_inline’ ‘_mm256_loadu_si256’: target specific option mismatch
871 | _mm256_loadu_si256 (__m256i_u const *__P)
| ^~~~~~~~~~~~~~~~~~
submission/solve.c:231:33: note: called from here
231 | __m256i v = _mm256_loadu_si256((const __m256i *)ip);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:871:1: error: inlining failed in call to ‘always_inline’ ‘_mm256_loadu_si256’: target specific option mismatch
871 | _mm256_loadu_si256 (__m256i_u const *__P)
| ^~~~~~~~~~~~~~~~~~
submission/solve.c:231:33: note: called from here
231 | __m256i v = _mm256_loadu_si256((const __m256i *)ip);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--- Command finished with exit code: 0 ---
assistant
I need to wrap this inner block in an avx2-tagged helper function since the outer function isn't tagged.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": "static int g_have_avx2 = -1;\nstatic inline int have_avx2(void) {\n if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports(\"avx2\") ? 1 : 0;\n return g_have_avx2;\n}\n\n// Runs the AVX2 16-wide 3-byte fast path as far as it goes; returns updated\n// (ip, op) via out-params. Only called when have_avx2() is true.\n__attribute__((target(\"avx2\")))\nstatic inline void run_3byte_avx2(const uint16_t **ipp, const uint16_t *end, uint8_t **opp) {\n const uint16_t *ip = *ipp;\n uint8_t *op = *opp;\n while (ip + 16 <= end) {\n __m256i v = _mm256_loadu_si256((const __m256i *)ip);\n if (!all_3byte16(v)) break;\n encode16_3byte(v, op);\n ip += 16;\n op += 48;\n }\n *ipp = ip;\n *opp = op;\n}", "old_string": "static int g_have_avx2 = -1;\nstatic inline int have_avx2(void) {\n if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports(\"avx2\") ? 1 : 0;\n return g_have_avx2;\n}"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
79+ }
81+ // Runs the AVX2 16-wide 3-byte fast path as far as it goes; returns updated
82+ // (ip, op) via out-params. Only called when have_avx2() is true.
83+ __attribute__((target("avx2")))
84+ static inline void run_3byte_avx2(const uint16_t **ipp, const uint16_t *end, uint8_t **opp) {
85+ const uint16_t *ip = *ipp;
86+ uint8_t *op = *opp;
87+ while (ip + 16 <= end) {
88+ __m256i v = _mm256_loadu_si256((const __m256i *)ip);
89+ if (!all_3byte16(v)) break;
90+ encode16_3byte(v, op);
91+ ip += 16;
92+ op += 48;
93+ }
94+ *ipp = ip;
95+ *opp = op;
Context after edit (lines 72-99):
72│ _mm_storeu_si128((__m128i *)(out + 36), _mm256_extracti128_si256(hi4, 1));
73│ }
74│
75│ static int g_have_avx2 = -1;
76│ static inline int have_avx2(void) {
77│ if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports("avx2") ? 1 : 0;
78│ return g_have_avx2;
79│ }
80│
81│ // Runs the AVX2 16-wide 3-byte fast path as far as it goes; returns updated
82│ // (ip, op) via out-params. Only called when have_avx2() is true.
83│ __attribute__((target("avx2")))
84│ static inline void run_3byte_avx2(const uint16_t **ipp, const uint16_t *end, uint8_t **opp) {
85│ const uint16_t *ip = *ipp;
86│ uint8_t *op = *opp;
87│ while (ip + 16 <= end) {
88│ __m256i v = _mm256_loadu_si256((const __m256i *)ip);
89│ if (!all_3byte16(v)) break;
90│ encode16_3byte(v, op);
91│ ip += 16;
92│ op += 48;
93│ }
94│ *ipp = ip;
95│ *opp = op;
96│ }
97│
98│ #define INVALID ((size_t)-1)
99│
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n if (have_avx2()) {\n run_3byte_avx2(&ip, end, &op);\n }\n while (ip + 8 <= end) {", "old_string": " } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {\n if (have_avx2()) {\n while (ip + 16 <= end) {\n __m256i v = _mm256_loadu_si256((const __m256i *)ip);\n if (!all_3byte16(v)) break;\n encode16_3byte(v, op);\n ip += 16;\n op += 48;\n }\n }\n while (ip + 8 <= end) {"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
247- while (ip + 16 <= end) {
248- __m256i v = _mm256_loadu_si256((const __m256i *)ip);
249- if (!all_3byte16(v)) break;
250- encode16_3byte(v, op);
251- ip += 16;
252- op += 48;
253- }
247+ run_3byte_avx2(&ip, end, &op);
Context after edit (lines 242-252):
242│ ip++;
243│ } while (ip < end && (c = *ip) < 0x80);
244│ }
245│ } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
246│ if (have_avx2()) {
247│ run_3byte_avx2(&ip, end, &op);
248│ }
249│ while (ip + 8 <= end) {
250│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
251│ if (!all_3byte(v)) break;
252│ encode8_3byte(v, op);
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
41435767
--- Command finished with exit code: 0 ---
assistant
Worse than pure SSSE3 (34.3M). The have_avx2() branch check adds overhead each time entering the 3-byte state. Let's check per-corpus.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (avx2 hybrid) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cghyb_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cghyb_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (avx2 hybrid) ==
2475272
== latin (avx2 hybrid) ==
10778548
== cjk (avx2 hybrid) ==
11883634
== emoji (avx2 hybrid) ==
14086639
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cp /tmp/solve_ssse3_backup.c /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c\ncd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (pure ssse3 best) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgbest_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgbest_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (pure ssse3 best) ==
2050149
== latin (pure ssse3 best) ==
8761156
== cjk (pure ssse3 best) ==
9770477
== emoji (pure ssse3 best) ==
12073214
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.6s
verify 1.9s PASS
measure 0.4s 34,311,457 instructions (given: 78,181,481)
SCORE +1.1881 (2.279x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | sed -n '90,110p'"}
tool result
__m128i sbit32 = _mm_set1_epi32((int)0x80000000u);
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
__m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
__m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i allok = _mm_and_si128(hi_ok, lo_ok);
return _mm_movemask_epi8(allok) == 0xFFFF;
}
// Vectorized encode of 4 valid surrogate pairs (packed as in
// all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).
static inline __m128i encode4_pairs(__m128i v) {
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
--- Command finished with exit code: 0 ---
assistant
Good, we're back to the 2.279x score baseline. Let's keep pushing SSSE3-only optimizations further. Let's profile the current best in detail.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '1,100p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_real.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 1144101
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 3571, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
7,692,404 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
4,525,426 (58.83%) submission/solve.c:utf16_to_utf8 [/tmp/runner_cur]
2,053,339 (26.69%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8
557,960 ( 7.25%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_3byte [/tmp/runner_cur]
201,648 ( 2.62%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_2byte [/tmp/runner_cur]
128,760 ( 1.67%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:encode8_3byte
95,312 ( 1.24%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:run_3byte_avx2
62,402 ( 0.81%) submission/solve.c:run_3byte_avx2 [/tmp/runner_cur]
--------------------------------------------------------------------------------
-- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h
--------------------------------------------------------------------------------
Ir
-- line 130 ----------------------------------------
. _mm_mulhrs_pi16 (__m64 __X, __m64 __Y)
. {
. return (__m64) __builtin_ia32_pmulhrsw ((__v4hi)__X, (__v4hi)__Y);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
. {
128,760 ( 1.67%) return (__m128i) __builtin_ia32_pshufb128 ((__v16qi)__X, (__v16qi)__Y);
. }
.
. extern __inline __m64 __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_shuffle_pi8 (__m64 __X, __m64 __Y)
. {
. return (__m64) __builtin_ia32_pshufb ((__v8qi)__X, (__v8qi)__Y);
. }
.
-- line 146 ----------------------------------------
--------------------------------------------------------------------------------
-- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h
--------------------------------------------------------------------------------
Ir
-- line 260 ----------------------------------------
. {
. return (__m256i) ((__v32qs)__A > (__v32qs)__B);
. }
.
. extern __inline __m256i
. __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
. _mm256_cmpgt_epi16 (__m256i __A, __m256i __B)
. {
20,720 ( 0.27%) return (__m256i) ((__v16hi)__A > (__v16hi)__B);
. }
.
. extern __inline __m256i
. __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
. _mm256_cmpgt_epi32 (__m256i __A, __m256i __B)
. {
. return (__m256i) ((__v8si)__A > (__v8si)__B);
. }
-- line 276 ----------------------------------------
-- line 427 ----------------------------------------
. {
. return (__m256i)__builtin_ia32_pminud256 ((__v8si)__A, (__v8si)__B);
. }
.
. extern __inline int
. __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
. _mm256_movemask_epi8 (__m256i __A)
. {
4,144 ( 0.05%) return __builtin_ia32_pmovmskb256 ((__v32qi)__A);
. }
.
. extern __inline __m256i
. __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
. _mm256_cvtepi8_epi16 (__m128i __X)
. {
. return (__m256i) __builtin_ia32_pmovsxbw256 ((__v16qi)__X);
. }
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh\ncallgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '1,40p'"}
tool result
34311483
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_real.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 1004897
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 3770, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
6,377,031 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
3,561,778 (55.85%) submission/solve.c:utf16_to_utf8 [/tmp/runner_cur]
1,867,616 (29.29%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8
557,960 ( 8.75%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_3byte [/tmp/runner_cur]
201,648 ( 3.16%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:encode8_2byte [/tmp/runner_cur]
128,760 ( 2.02%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:encode8_3byte
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
-- line 42 ----------------------------------------
. (char)0x80, (char)0x80, (char)7,
. (char)0x80, (char)0x80, (char)0x80, (char)0x80);
.
--- Command finished with exit code: 0 ---
assistant
Good, back to the clean version. Let's look at the tail-handling logic to see if there's redundant work — after breaking out of vectorized loop, we recompute `c = *ip` and re-check condition unnecessarily but it's cheap. Let's check the main loop structure for the biggest remaining cost centers.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '40,140p'"}
tool result
. return (__m64) __builtin_ia32_pmulhrsw ((__v4hi)__X, (__v4hi)__Y);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_shuffle_epi8 (__m128i __X, __m128i __Y)
. {
128,760 ( 2.02%) return (__m128i) __builtin_ia32_pshufb128 ((__v16qi)__X, (__v16qi)__Y);
. }
.
. extern __inline __m64 __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_shuffle_pi8 (__m64 __X, __m64 __Y)
. {
. return (__m64) __builtin_ia32_pshufb ((__v8qi)__X, (__v8qi)__Y);
. }
.
-- line 146 ----------------------------------------
--------------------------------------------------------------------------------
-- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h
--------------------------------------------------------------------------------
Ir
-- line 699 ----------------------------------------
. _mm_load_si128 (__m128i const *__P)
. {
. return *__P;
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_loadu_si128 (__m128i_u const *__P)
. {
150,162 ( 2.35%) return *__P;
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_loadl_epi64 (__m128i_u const *__P)
. {
. return _mm_set_epi64 ((__m64)0LL, *(__m64_u *)__P);
. }
.
-- line 715 ----------------------------------------
-- line 735 ----------------------------------------
. _mm_store_si128 (__m128i *__P, __m128i __B)
. {
. *__P = __B;
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storeu_si128 (__m128i_u *__P, __m128i __B)
. {
66,001 ( 1.03%) *__P = __B;
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storel_epi64 (__m128i_u *__P, __m128i __B)
. {
62,592 ( 0.98%) *(__m64_u *)__P = (__m64) ((__v2di)__B)[0];
. }
.
. extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_storeu_si64 (void *__P, __m128i __B)
. {
. _mm_storel_epi64 ((__m128i_u *)__P, __B);
. }
.
-- line 757 ----------------------------------------
-- line 999 ----------------------------------------
. _mm_packs_epi32 (__m128i __A, __m128i __B)
. {
. return (__m128i)__builtin_ia32_packssdw128 ((__v4si)__A, (__v4si)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_packus_epi16 (__m128i __A, __m128i __B)
. {
143,321 ( 2.25%) return (__m128i)__builtin_ia32_packuswb128 ((__v8hi)__A, (__v8hi)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_unpackhi_epi8 (__m128i __A, __m128i __B)
. {
. return (__m128i)__builtin_ia32_punpckhbw128 ((__v16qi)__A, (__v16qi)__B);
. }
.
-- line 1015 ----------------------------------------
-- line 1065 ----------------------------------------
. _mm_add_epi16 (__m128i __A, __m128i __B)
. {
. return (__m128i) ((__v8hu)__A + (__v8hu)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_add_epi32 (__m128i __A, __m128i __B)
. {
23,324 ( 0.37%) return (__m128i) ((__v4su)__A + (__v4su)__B);
. }
.
. extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
. _mm_add_epi64 (__m128i __A, __m128i __B)
. {
. return (__m128i) ((__v2du)__A + (__v2du)__B);
--- Command finished with exit code: 0 ---
assistant
This is fairly efficient already. Let's check how the tail scalar handling for the CJK path might be improved, since we're at diminishing returns for the vectorized bulk portion. Let's see the assembly loop structure for the 3-byte hot path itself.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | sed -n '/<encode8_3byte>:/,/^0000/p' | head -60"}
tool result
0000000000001440 <encode8_3byte>:
1440: 66 0f 76 d2 pcmpeqd xmm2,xmm2
1444: 66 0f 6f c8 movdqa xmm1,xmm0
1448: 66 0f 6f d8 movdqa xmm3,xmm0
144c: b8 e0 00 e0 00 mov eax,0xe000e0
1451: 66 0f 71 d1 0c psrlw xmm1,0xc
1456: 66 0f 71 d3 06 psrlw xmm3,0x6
145b: 66 0f 6f e2 movdqa xmm4,xmm2
145f: 66 0f 71 d4 0c psrlw xmm4,0xc
1464: 66 0f 71 d2 0a psrlw xmm2,0xa
1469: 66 0f db cc pand xmm1,xmm4
146d: 66 0f 6e e0 movd xmm4,eax
1471: b8 80 00 80 00 mov eax,0x800080
1476: 66 0f db da pand xmm3,xmm2
147a: 66 0f db c2 pand xmm0,xmm2
147e: 66 0f 70 e4 00 pshufd xmm4,xmm4,0x0
1483: 66 0f eb cc por xmm1,xmm4
1487: 66 0f 6e e0 movd xmm4,eax
148b: 66 0f 70 e4 00 pshufd xmm4,xmm4,0x0
1490: 66 0f eb dc por xmm3,xmm4
1494: 66 0f eb c4 por xmm0,xmm4
1498: 66 0f 67 cb packuswb xmm1,xmm3
149c: 66 0f 67 c0 packuswb xmm0,xmm0
14a0: 66 0f 6f d0 movdqa xmm2,xmm0
14a4: 66 0f 6f d9 movdqa xmm3,xmm1
14a8: 66 0f 38 00 05 7f 0b pshufb xmm0,XMMWORD PTR [rip+0xb7f] # 2030 <_IO_stdin_used+0x30>
14af: 00 00
14b1: 66 0f 38 00 15 56 0b pshufb xmm2,XMMWORD PTR [rip+0xb56] # 2010 <_IO_stdin_used+0x10>
14b8: 00 00
14ba: 66 0f 38 00 1d 5d 0b pshufb xmm3,XMMWORD PTR [rip+0xb5d] # 2020 <_IO_stdin_used+0x20>
14c1: 00 00
14c3: 66 0f 38 00 0d 74 0b pshufb xmm1,XMMWORD PTR [rip+0xb74] # 2040 <_IO_stdin_used+0x40>
14ca: 00 00
14cc: 66 0f eb d3 por xmm2,xmm3
14d0: 66 0f eb c1 por xmm0,xmm1
14d4: 0f 11 17 movups XMMWORD PTR [rdi],xmm2
14d7: 0f 11 47 0c movups XMMWORD PTR [rdi+0xc],xmm0
14db: c3 ret
14dc: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
00000000000014e0 <encode8_2byte>:
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && grep -n \"static inline void encode8_3byte\\|static inline __m128i encode8_2byte\\|static inline __m128i encode4_pairs\" submission/solve.c"}
tool result
13:static inline void encode8_3byte(__m128i v, uint8_t *out) {
76:static inline __m128i encode8_2byte(__m128i v) {
106:static inline __m128i encode4_pairs(__m128i v) {
--- Command finished with exit code: 0 ---
assistant
This is already tight (~20 instructions for encoding 8 units into 24 bytes). Let's check if idxAB constants being loaded from memory each call could be hoisted—since they're local `const` they get reloaded from .rodata each call, but compiler seems to keep them as constants loaded once per call (not per-iteration overhead beyond mov). Let's check the calling loop.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | sed -n '/<utf16_to_utf8>:/,/^0000/p' | grep -B2 -A2 \"call.*encode8_3byte\""}
tool result
1a53: 66 0f 6f c2 movdqa xmm0,xmm2
1a57: 48 83 c2 18 add rdx,0x18
1a5b: e8 e0 f9 ff ff call 1440 <encode8_3byte>
1a60: 49 8d 40 10 lea rax,[r8+0x10]
1a64: 48 39 c6 cmp rsi,rax
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '1,80p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#define INVALID ((size_t)-1)
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
__m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
(char)1, (char)9, (char)0x80,
(char)2, (char)10, (char)0x80,
(char)3, (char)11, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
(char)0x80, (char)0x80, (char)1,
(char)0x80, (char)0x80, (char)2,
(char)0x80, (char)0x80, (char)3,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
(char)5, (char)13, (char)0x80,
(char)6, (char)14, (char)0x80,
(char)7, (char)15, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
(char)0x80, (char)0x80, (char)5,
(char)0x80, (char)0x80, (char)6,
(char)0x80, (char)0x80, (char)7,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
__m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
__m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
_mm_storeu_si128((__m128i *)(out + 0), lo4);
_mm_storeu_si128((__m128i *)(out + 12), hi4);
}
// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
static inline int all_3byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
__m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i bad = _mm_or_si128(lomask, surrmask);
return _mm_movemask_epi8(bad) == 0;
}
// True iff all 8 code units in v are in [0x0080,0x07FF].
static inline int all_2byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
__m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x0780 ^ 0x8000)));
return _mm_movemask_epi8(inrange) == 0xFFFF;
}
// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
// 16 bytes of UTF-8.
__attribute__((target("ssse3")))
static inline __m128i encode8_2byte(__m128i v) {
__m128i hi = _mm_srli_epi16(v, 6);
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && sed -i 's/__attribute__((target(\"ssse3\")))\\nstatic inline void encode8_3byte/XX/' submission/solve.c\ngrep -n \"target(\\\"ssse3\\\"))\" submission/solve.c"}
tool result
12:__attribute__((target("ssse3")))
75:__attribute__((target("ssse3")))
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "grep -n \"^size_t utf16_to_utf8\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
129:size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '125,230p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
return word;
}
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
}
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
(void)lo;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
} else if (ip < end && c >= 0xDC00 && c < 0xE000) {
return INVALID;
}
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
assistant
Key insight: `encode8_3byte` is `target("ssse3")` but is called from the default-target main function, so it isn't inlined (we saw a `call` instruction). Let's mark the whole `utf16_to_utf8` function `target("ssse3")` to allow inlining.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": "__attribute__((target(\"ssse3\")))\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {", "old_string": "size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
129+ __attribute__((target("ssse3")))
Context after edit (lines 126-133):
126│ }
127│
128│
129│ __attribute__((target("ssse3")))
130│ size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
131│ uint8_t *op = out;
132│ const uint16_t *ip = in;
133│ const uint16_t *end = in + n;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
33102083
--- Command finished with exit code: 0 ---
assistant
Improvement from inlining!
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 33,102,083 instructions (given: 78,181,481)
SCORE +1.2399 (2.362x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | head -20"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#define INVALID ((size_t)-1)
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
--- Command finished with exit code: 0 ---
assistant
Let's add a safe fallback path for portability, keeping performance intact.
tool call: bash
{"command": "sed -n '1,10p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c\ngrep -n \"^size_t utf16_to_utf8\\|^__attribute__((target(\\\"ssse3\\\")))$\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#define INVALID ((size_t)-1)
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
12:__attribute__((target("ssse3")))
75:__attribute__((target("ssse3")))
129:__attribute__((target("ssse3")))
130:size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '125,230p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
return word;
}
__attribute__((target("ssse3")))
size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
}
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
(void)lo;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
} else if (ip < end && c >= 0xDC00 && c < 0xE000) {
return INVALID;
}
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && sed -n '1,5p' submission/solve.c"}
tool result
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <emmintrin.h>
#include <tmmintrin.h>
--- Command finished with exit code: 0 ---
assistant
Let's add architecture portability guards for safety, falling back to scalar on non-x86.
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c | wc -l"}
tool result
231
--- Command finished with exit code: 0 ---
tool call: write
{"content": "// solve.c \u2014 optimized utf16_to_utf8.\n//\n// Strategy: scalar loop with SSSE3-vectorized inner kernels for each of the\n// four encoding classes (ASCII, 2-byte, 3-byte, surrogate-pair-to-4-byte).\n// Each kernel processes 8 code units at a time as long as they all belong to\n// the same class, falling back to a scalar loop at class boundaries and\n// buffer tails. Falls back to a portable scalar implementation when SSE2 is\n// unavailable (e.g. non-x86 builds), or when SSSE3 (pshufb) is unavailable.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n#if defined(__x86_64__) || defined(__i386__)\n#include <emmintrin.h>\n#include <tmmintrin.h>\n#define UTF16_HAVE_SSE2 1\n#endif\n\n#ifdef UTF16_HAVE_SSE2\n\n// Vectorized encode of 8 code units, all known to be in the \"3-byte\" range\n// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two\n// 12-byte groups).\n__attribute__((target(\"ssse3\")))\nstatic inline void encode8_3byte(__m128i v, uint8_t *out) {\n __m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));\n hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));\n __m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));\n mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));\n __m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));\n lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));\n\n __m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7\n __m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)\n\n const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,\n (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80,\n (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,\n (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2,\n (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,\n (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80,\n (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,\n (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6,\n (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n\n __m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));\n __m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), lo4);\n _mm_storeu_si128((__m128i *)(out + 12), hi4);\n}\n\n// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].\nstatic inline int all_3byte(__m128i v) {\n __m128i sbit = _mm_set1_epi16((short)0x8000);\n __m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),\n _mm_set1_epi16((short)(0x800 ^ 0x8000)));\n __m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));\n __m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),\n _mm_set1_epi16((short)(0x800 ^
... [9161 characters truncated for page size]
tool result
Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c (294 lines):
1+ // solve.c — optimized utf16_to_utf8.
2+ //
3+ // Strategy: scalar loop with SSSE3-vectorized inner kernels for each of the
4+ // four encoding classes (ASCII, 2-byte, 3-byte, surrogate-pair-to-4-byte).
5+ // Each kernel processes 8 code units at a time as long as they all belong to
6+ // the same class, falling back to a scalar loop at class boundaries and
7+ // buffer tails. Falls back to a portable scalar implementation when SSE2 is
8+ // unavailable (e.g. non-x86 builds), or when SSSE3 (pshufb) is unavailable.
13+ #define INVALID ((size_t)-1)
15+ #if defined(__x86_64__) || defined(__i386__)
18+ #define UTF16_HAVE_SSE2 1
19+ #endif
7- #define INVALID ((size_t)-1)
21+ #ifdef UTF16_HAVE_SSE2
130- size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
143+ static size_t utf16_to_utf8_vec(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
196- (void)lo;
244+ #endif // UTF16_HAVE_SSE2
246+ // Portable scalar fallback (used when SSSE3 is unavailable at runtime, or on
247+ // non-x86 targets).
...
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
33132300
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 33,132,300 instructions (given: 78,181,481)
SCORE +1.2386 (2.360x)
--- Command finished with exit code: 0 ---
assistant
Slight overhead from the extra function-pointer dispatch check but negligible, and now safer/portable. Let's run the full gate to be sure and check a couple more random seeds.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full --seed 1 2>&1 | tail -10\n./grade --seed 42 2>&1 | tail -10\n./grade --seed 999 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS (FULL gate)
measure 0.5s 33,132,300 instructions (given: 78,181,481)
SCORE +1.2386 (2.360x)
build 0.7s
verify 2.0s PASS
measure 1.3s 32,994,570 instructions (given: 77,692,405)
SCORE +1.2355 (2.355x)
build 0.7s
verify 1.9s PASS
measure 1.3s 33,057,291 instructions (given: 78,113,354)
SCORE +1.2406 (2.363x)
--- Command finished with exit code: 0 ---
assistant
Consistent ~2.36x across seeds. Let's try to squeeze more. Let's check the ASCII path bulk copy since it seems well optimized, and look at ways to widen the surrogate-pair kernel handling since it's still notably costly.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f (current) ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgcur_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgcur_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii (current) ==
2050217
== latin (current) ==
8366653
== cjk (current) ==
8891624
== emoji (current) ==
12320871
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | sed -n '/<all_surrogate_pairs>:/,/^0000/p' | head -30\nobjdump -d /tmp/runner_cur -M intel | sed -n '/<encode4_pairs>:/,/^0000/p' | head -40"}
tool result
--- Command finished with exit code: 0 ---
assistant
Both inlined into the loop (no standalone symbols now). Let's disasm the emoji-processing part of the loop.
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | sed -n '/<utf16_to_utf8_vec>:/,/^0000/p' | wc -l"}
tool result
400
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | sed -n '/<utf16_to_utf8_vec>:/,/^0000/p' | grep -n \"0xd800\\|0xdc00\\|surrogate\" "}
tool result
21: 29d2: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
150: 2bf2: 41 81 e8 00 dc 00 00 sub r8d,0xdc00
225: 2d52: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
228: 2d66: 81 ea 00 dc 00 00 sub edx,0xdc00
234: 2d85: 45 8d 88 00 24 ff ff lea r9d,[r8-0xdc00]
237: 2d95: 81 ea 00 d8 00 00 sub edx,0xd800
338: 2f5b: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
348: 2f8f: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | sed -n '2900,2980p'"}
tool result
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | awk '/<utf16_to_utf8_vec>:/{f=1} f' | sed -n '225,320p'"}
tool result
2d52: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
2d59: 41 81 f8 ff 03 00 00 cmp r8d,0x3ff
2d60: 0f 86 ca 02 00 00 jbe 3030 <utf16_to_utf8_vec+0x6b0>
2d66: 81 ea 00 dc 00 00 sub edx,0xdc00
2d6c: 81 fa ff 03 00 00 cmp edx,0x3ff
2d72: 0f 87 48 fc ff ff ja 29c0 <utf16_to_utf8_vec+0x40>
2d78: 48 c7 c0 ff ff ff ff mov rax,0xffffffffffffffff
2d7f: c3 ret
2d80: 44 0f b7 41 02 movzx r8d,WORD PTR [rcx+0x2]
2d85: 45 8d 88 00 24 ff ff lea r9d,[r8-0xdc00]
2d8c: 41 81 f9 ff 03 00 00 cmp r9d,0x3ff
2d93: 77 e3 ja 2d78 <utf16_to_utf8_vec+0x3f8>
2d95: 81 ea 00 d8 00 00 sub edx,0xd800
2d9b: 48 83 c1 04 add rcx,0x4
2d9f: 48 83 c0 04 add rax,0x4
2da3: c1 e2 0a shl edx,0xa
2da6: 44 01 c2 add edx,r8d
2da9: 44 8d 8a 00 24 00 00 lea r9d,[rdx+0x2400]
2db0: c1 ea 06 shr edx,0x6
2db3: 45 89 c8 mov r8d,r9d
2db6: 45 89 ca mov r10d,r9d
2db9: 81 c2 90 00 00 00 add edx,0x90
2dbf: 41 c1 e1 18 shl r9d,0x18
2dc3: 41 c1 e8 04 shr r8d,0x4
2dc7: 41 c1 ea 12 shr r10d,0x12
2dcb: 41 81 e1 00 00 00 3f and r9d,0x3f000000
2dd2: 41 81 e0 00 3f 00 00 and r8d,0x3f00
2dd9: c1 e2 10 shl edx,0x10
2ddc: 45 09 d0 or r8d,r10d
2ddf: 81 e2 00 00 3f 00 and edx,0x3f0000
2de5: 45 09 c8 or r8d,r9d
2de8: 4c 8d 49 02 lea r9,[rcx+0x2]
2dec: 44 09 c2 or edx,r8d
2def: 81 ca f0 80 80 80 or edx,0x808080f0
2df5: 89 50 fc mov DWORD PTR [rax-0x4],edx
2df8: 49 39 f9 cmp r9,rdi
2dfb: 0f 83 ff 01 00 00 jae 3000 <utf16_to_utf8_vec+0x680>
2e01: 0f b7 11 movzx edx,WORD PTR [rcx]
2e04: 41 89 d0 mov r8d,edx
2e07: 66 41 81 c0 00 28 add r8w,0x2800
2e0d: 66 41 81 f8 ff 03 cmp r8w,0x3ff
2e13: 0f 87 e7 01 00 00 ja 3000 <utf16_to_utf8_vec+0x680>
2e19: 49 39 f9 cmp r9,rdi
2e1c: 0f 82 5e ff ff ff jb 2d80 <utf16_to_utf8_vec+0x400>
2e22: 48 c7 c0 ff ff ff ff mov rax,0xffffffffffffffff
2e29: c3 ret
2e2a: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0]
2e30: 4c 8d 41 10 lea r8,[rcx+0x10]
2e34: 4c 39 c7 cmp rdi,r8
2e37: 0f 82 13 02 00 00 jb 3050 <utf16_to_utf8_vec+0x6d0>
2e3d: b9 00 28 00 28 mov ecx,0x28002800
2e42: 66 0f 76 d2 pcmpeqd xmm2,xmm2
2e46: 66 44 0f 6e f1 movd xmm14,ecx
2e4b: 66 0f 71 f2 0f psllw xmm2,0xf
2e50: b9 00 88 00 88 mov ecx,0x88008800
2e55: 66 0f 6e f1 movd xmm6,ecx
2e59: b9 e0 00 e0 00 mov ecx,0xe000e0
2e5e: 66 45 0f 70 f6 00 pshufd xmm14,xmm14,0x0
2e64: 66 44 0f 6e f9 movd xmm15,ecx
2e69: 66 0f 70 f6 00 pshufd xmm6,xmm6,0x0
2e6e: 66 45 0f 70 ff 00 pshufd xmm15,xmm15,0x0
2e74: e9 97 00 00 00 jmp 2f10 <utf16_to_utf8_vec+0x590>
2e79: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0]
2e80: 66 0f 6f c8 movdqa xmm1,xmm0
2e84: 66 0f 6f e8 movdqa xmm5,xmm0
2e88: 66 0f 76 ff pcmpeqd xmm7,xmm7
2e8c: 48 83 c0 18 add rax,0x18
2e90: 66 45 0f 76 c0 pcmpeqd xmm8,xmm8
2e95: 66 0f 71 d7 0c psrlw xmm7,0xc
2e9a: 49 8d 50 10 lea rdx,[r8+0x10]
2e9e: 66 41 0f 71 d0 0a psrlw xmm8,0xa
2ea4: 66 0f 71 d1 0c psrlw xmm1,0xc
2ea9: 66 0f 71 d5 06 psrlw xmm5,0x6
2eae: 66 0f db cf pand xmm1,xmm7
2eb2: 66 41 0f db c0 pand xmm0,xmm8
2eb7: 66 41 0f db e8 pand xmm5,xmm8
2ebc: 66 41 0f eb cf por xmm1,xmm15
2ec1: 66 0f eb c3 por xmm0,xmm3
2ec5: 66 0f eb eb por xmm5,xmm3
2ec9: 66 0f 67 c0 packuswb xmm0,xmm0
2ecd: 66 0f 67 cd packuswb xmm1,xmm5
2ed1: 66 0f 6f f8 movdqa xmm7,xmm0
2ed5: 66 41 0f 38 00 c3 pshufb xmm0,xmm11
2edb: 66 0f 6f e9 movdqa xmm5,xmm1
2edf: 66 41 0f 38 00 fd pshufb xmm7,xmm13
2ee5: 66 0f 38 00 0d 52 11 pshufb xmm1,XMMWORD PTR [rip+0x1152] # 4040 <_IO_stdin_used+0x40>
2eec: 00 00
2eee: 66 41 0f 38 00 ec pshufb xmm5,xmm12
2ef4: 66 0f eb c8 por xmm1,xmm0
2ef8: 66 0f eb ef por xmm5,xmm7
2efc: 0f 11 68 e8 movups XMMWORD PTR [rax-0x18],xmm5
2f00: 0f 11 48 f4 movups XMMWORD PTR [rax-0xc],xmm1
2f04: 48 39 d7 cmp rdi,rdx
2f07: 0f 82 13 01 00 00 jb 3020 <utf16_to_utf8_vec+0x6a0>
2f0d: 49 89 d0 mov r8,rdx
2f10: f3 41 0f 6f 40 f0 movdqu xmm0,XMMWORD PTR [r8-0x10]
--- Command finished with exit code: 0 ---
assistant
This is quite good. Let's compute the overall score once more, and try a couple micro-optimizations: combine the "all_2byte" check with encode inline (already done), check if branch order matters (put the most common branch first).
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\ncnt1=cnt2=cnt3=cnt4=0\ndef classify(c):\n if c<0x80: return 1\n if c<0x800: return 2\n if c<0xD800 or c>=0xE000: return 3\n return 4\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c=units[i]\n cls=classify(c)\n if cls==1: cnt1+=1; i+=1\n elif cls==2: cnt2+=1; i+=1\n elif cls==3: cnt3+=1; i+=1\n else: cnt4+=1; i+=2\nprint(cnt1,cnt2,cnt3,cnt4)\ntotal=cnt1+cnt2+cnt3+cnt4\nprint([x/total for x in (cnt1,cnt2,cnt3,cnt4)])\n\""}
tool result
578313 136813 186156 52401
[0.6063996107721329, 0.14345752204873108, 0.19519693650825273, 0.054945930670883304]
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/ascii16_sse.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"sse2\")))\nstatic inline int all_ascii16_sse(__m128i a, __m128i b) {\n __m128i hi = _mm_or_si128(_mm_and_si128(a, _mm_set1_epi16((short)0xFF80)),\n _mm_and_si128(b, _mm_set1_epi16((short)0xFF80)));\n return _mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) == 0xFFFF;\n}\n\nint main(void) {\n srand(1);\n int bad=0;\n for (int t=0;t<100000;t++) {\n uint16_t units[16];\n for (int i=0;i<16;i++) units[i] = rand()%0x80;\n __m128i a = _mm_loadu_si128((const __m128i*)units);\n __m128i b = _mm_loadu_si128((const __m128i*)(units+8));\n if (!all_ascii16_sse(a,b)) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/ascii16_sse /tmp/ascii16_sse.c && /tmp/ascii16_sse"}
tool result
bad=0
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\ntotal=0\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4+2*cnt\n total+=cnt\nprint(total)\n\""}
tool result
1006084
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/ascii16v2.c << 'EOF'\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <emmintrin.h>\n#include <stdio.h>\n#include <stdlib.h>\n\n__attribute__((target(\"sse2\")))\nstatic inline int all_ascii16_v2(__m128i a, __m128i b, __m128i *packedOut) {\n __m128i orv = _mm_or_si128(a, b);\n __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));\n int ok = _mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) == 0xFFFF;\n *packedOut = _mm_packus_epi16(a, b);\n return ok;\n}\n\nint main(void) {\n srand(1);\n int bad=0;\n for (int t=0;t<100000;t++) {\n uint16_t units[16];\n for (int i=0;i<16;i++) units[i] = rand()%0x80;\n __m128i a = _mm_loadu_si128((const __m128i*)units);\n __m128i b = _mm_loadu_si128((const __m128i*)(units+8));\n __m128i packed;\n int ok = all_ascii16_v2(a,b,&packed);\n if (!ok) { bad++; continue; }\n uint8_t out[16];\n _mm_storeu_si128((__m128i*)out, packed);\n for (int i=0;i<16;i++) if (out[i]!=units[i]) bad++;\n }\n printf(\"bad=%d\\n\", bad);\n return bad!=0;\n}\nEOF\ncc -O2 -std=c17 -o /tmp/ascii16v2 /tmp/ascii16v2.c && /tmp/ascii16v2"}
tool result
bad=0
--- Command finished with exit code: 0 ---
assistant
This computes packus even when it might not be used, but it's cheap (both branches are computed unconditionally with no extra load). Let's try replacing the 8-wide ASCII loop with a 16-wide SSE2 loop (only needs SSE2, no SSSE3 needed) to halve loop overhead there since ASCII is 60% of units.
tool call: bash
{"command": "sed -n '135,155p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
word = _mm_or_si128(word, b0);
word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
return word;
}
__attribute__((target("ssse3")))
static size_t utf16_to_utf8_vec(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
--- Command finished with exit code: 0 ---
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 16 <= end) {\n __m128i a = _mm_loadu_si128((const __m128i *)ip);\n __m128i b = _mm_loadu_si128((const __m128i *)(ip + 8));\n __m128i orv = _mm_or_si128(a, b);\n __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(a, b);\n _mm_storeu_si128((__m128i *)op, packed);\n ip += 16;\n op += 16;\n }\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);", "old_string": " uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
150+ while (ip + 16 <= end) {
151+ __m128i a = _mm_loadu_si128((const __m128i *)ip);
152+ __m128i b = _mm_loadu_si128((const __m128i *)(ip + 8));
153+ __m128i orv = _mm_or_si128(a, b);
154+ __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));
155+ if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
156+ break;
157+ __m128i packed = _mm_packus_epi16(a, b);
158+ _mm_storeu_si128((__m128i *)op, packed);
159+ ip += 16;
160+ op += 16;
161+ }
Context after edit (lines 145-170):
145│ const uint16_t *ip = in;
146│ const uint16_t *end = in + n;
147│ while (ip < end) {
148│ uint32_t c = *ip;
149│ if (c < 0x80) {
150│ while (ip + 16 <= end) {
151│ __m128i a = _mm_loadu_si128((const __m128i *)ip);
152│ __m128i b = _mm_loadu_si128((const __m128i *)(ip + 8));
153│ __m128i orv = _mm_or_si128(a, b);
154│ __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));
155│ if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
156│ break;
157│ __m128i packed = _mm_packus_epi16(a, b);
158│ _mm_storeu_si128((__m128i *)op, packed);
159│ ip += 16;
160│ op += 16;
161│ }
162│ while (ip + 8 <= end) {
163│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
164│ __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
165│ if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
166│ break;
167│ __m128i packed = _mm_packus_epi16(v, v);
168│ _mm_storel_epi64((__m128i *)op, packed);
169│ ip += 8;
170│ op += 8;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
33261270
--- Command finished with exit code: 0 ---
assistant
Slightly worse (33.26M vs 33.13M). The extra 16-wide path adds overhead without benefit here. Let's revert that change.
tool call: edit
{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c", "new_string": " uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);", "old_string": " uint32_t c = *ip;\n if (c < 0x80) {\n while (ip + 16 <= end) {\n __m128i a = _mm_loadu_si128((const __m128i *)ip);\n __m128i b = _mm_loadu_si128((const __m128i *)(ip + 8));\n __m128i orv = _mm_or_si128(a, b);\n __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(a, b);\n _mm_storeu_si128((__m128i *)op, packed);\n ip += 16;\n op += 16;\n }\n while (ip + 8 <= end) {\n __m128i v = _mm_loadu_si128((const __m128i *)ip);\n __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));\n if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)\n break;\n __m128i packed = _mm_packus_epi16(v, v);"}
tool result
Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c: replaced 1 occurrence(s)
150- while (ip + 16 <= end) {
151- __m128i a = _mm_loadu_si128((const __m128i *)ip);
152- __m128i b = _mm_loadu_si128((const __m128i *)(ip + 8));
153- __m128i orv = _mm_or_si128(a, b);
154- __m128i hi = _mm_and_si128(orv, _mm_set1_epi16((short)0xFF80));
155- if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
156- break;
157- __m128i packed = _mm_packus_epi16(a, b);
158- _mm_storeu_si128((__m128i *)op, packed);
159- ip += 16;
160- op += 16;
161- }
Context after edit (lines 145-158):
145│ const uint16_t *ip = in;
146│ const uint16_t *end = in + n;
147│ while (ip < end) {
148│ uint32_t c = *ip;
149│ if (c < 0x80) {
150│ while (ip + 8 <= end) {
151│ __m128i v = _mm_loadu_si128((const __m128i *)ip);
152│ __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
153│ if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
154│ break;
155│ __m128i packed = _mm_packus_epi16(v, v);
156│ _mm_storel_epi64((__m128i *)op, packed);
157│ ip += 8;
158│ op += 8;
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
33132300
--- Command finished with exit code: 0 ---
assistant
Good, back to baseline. Let's try one more thing: reorder branch checks by putting the most common ASCII check first (already first) but try reordering 2-byte/3-byte order since 3-byte(19.5%) > 2-byte(14.3%).
tool call: bash
{"command": "grep -n \"} else if (c\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
168: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
186: } else if (c < 0x800) {
205: } else if (c < 0xDC00) {
257: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
262: } else if (c < 0x800) {
267: } else if (c < 0xDC00) {
--- Command finished with exit code: 0 ---
assistant
Already 3-byte before 2-byte. Good. Let's check verify pass and try a few more corpus seeds to check stability, then consider this near final. Let's also try increasing kernel width for 2-byte and pair paths using AVX2 (since those are shorter runs, might not help, but let's just verify with actual measurements rather than assumptions).
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 33,132,300 instructions (given: 78,181,481)
SCORE +1.2386 (2.360x)
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cp /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c /tmp/solve_final_ssse3.c\necho saved"}
tool result
saved
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\ncallgrind_annotate /tmp/cg_real.out 2>/dev/null | sed -n '1,30p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_real.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 938491
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 4496, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
6,130,400 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
3,514,959 (57.34%) submission/solve.c:utf16_to_utf8_vec [/tmp/runner_cur]
2,478,980 (40.44%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8_vec
130,536 ( 2.13%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:utf16_to_utf8_vec
--------------------------------------------------------------------------------
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_full.out /tmp/runner_cur .build/corpus_1.bin >/dev/null 2>&1\ncallgrind_annotate /tmp/cg_full.out 2>/dev/null | sed -n '1,120p'"}
tool result
--------------------------------------------------------------------------------
Profile data file '/tmp/cg_full.out' (creator: callgrind-3.25.1)
--------------------------------------------------------------------------------
I1 cache:
D1 cache:
LL cache:
Timerange: Basic block 0 - 938491
Trigger: Program termination
Profiled target: /tmp/runner_cur .build/corpus_1.bin (PID 4610, part 1)
Events recorded: Ir
Events shown: Ir
Event sort order: Ir
Thresholds: 99
Include dirs:
User annotated:
Auto-annotation: on
--------------------------------------------------------------------------------
Ir
--------------------------------------------------------------------------------
6,130,400 (100.0%) PROGRAM TOTALS
--------------------------------------------------------------------------------
Ir file:function
--------------------------------------------------------------------------------
3,514,959 (57.34%) submission/solve.c:utf16_to_utf8_vec [/tmp/runner_cur]
2,478,980 (40.44%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8_vec
130,536 ( 2.13%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:utf16_to_utf8_vec
--------------------------------------------------------------------------------
-- Auto-annotated source: submission/solve.c
--------------------------------------------------------------------------------
Ir
-- line 135 ----------------------------------------
. word = _mm_or_si128(word, b0);
. word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
. word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
. word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
. return word;
. }
.
. __attribute__((target("ssse3")))
1,184 ( 0.02%) static size_t utf16_to_utf8_vec(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
592 ( 0.01%) uint8_t *op = out;
. const uint16_t *ip = in;
592 ( 0.01%) const uint16_t *end = in + n;
12,276 ( 0.20%) while (ip < end) {
43,710 ( 0.71%) uint32_t c = *ip;
88,654 ( 1.45%) if (c < 0x80) {
316,383 ( 5.16%) while (ip + 8 <= end) {
. __m128i v = _mm_loadu_si128((const __m128i *)ip);
. __m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
189,807 ( 3.10%) if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
. break;
. __m128i packed = _mm_packus_epi16(v, v);
. _mm_storel_epi64((__m128i *)op, packed);
. ip += 8;
62,592 ( 1.02%) op += 8;
. }
43,816 ( 0.71%) if (ip >= end) break;
21,802 ( 0.36%) c = *ip;
43,604 ( 0.71%) if (c < 0x80) {
. do {
155,154 ( 2.53%) *op++ = (uint8_t)c;
77,577 ( 1.27%) ip++;
387,015 ( 6.31%) } while (ip < end && (c = *ip) < 0x80);
. }
160,248 ( 2.61%) } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
98,447 ( 1.61%) while (ip + 8 <= end) {
. __m128i v = _mm_loadu_si128((const __m128i *)ip);
55,052 ( 0.90%) if (!all_3byte(v)) break;
. encode8_3byte(v, op);
. ip += 8;
21,460 ( 0.35%) op += 24;
. }
8,332 ( 0.14%) if (ip >= end) break;
4,139 ( 0.07%) c = *ip;
24,326 ( 0.40%) if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
. do {
144,760 ( 2.36%) uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
. memcpy(op, &v, 4);
14,476 ( 0.24%) op += 3;
14,476 ( 0.24%) ip++;
104,573 ( 1.71%) } while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
. }
14,168 ( 0.23%) } else if (c < 0x800) {
82,133 ( 1.34%) while (ip + 8 <= end) {
. __m128i v = _mm_loadu_si128((const __m128i *)ip);
56,532 ( 0.92%) if (!all_2byte(v)) break;
. __m128i r = encode8_2byte(v);
. _mm_storeu_si128((__m128i *)op, r);
. ip += 8;
12,603 ( 0.21%) op += 16;
. }
21,104 ( 0.34%) if (ip >= end) break;
10,543 ( 0.17%) c = *ip;
31,629 ( 0.52%) if (c >= 0x80 && c < 0x800) {
. do {
215,934 ( 3.52%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
35,989 ( 0.59%) memcpy(op, &v, 2);
35,989 ( 0.59%) op += 2;
35,989 ( 0.59%) ip++;
251,523 ( 4.10%) } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
. }
14,168 ( 0.23%) } else if (c < 0xDC00) {
21,252 ( 0.35%) if (ip + 1 >= end) return INVALID;
7,084 ( 0.12%) uint32_t lo = ip[1];
21,252 ( 0.35%) if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
63,214 ( 1.03%) while (ip + 8 <= end) {
. __m128i v = _mm_loadu_si128((const __m128i *)ip);
41,962 ( 0.68%) if (!all_surrogate_pairs(v)) break;
. __m128i r = encode4_pairs(v);
. _mm_storeu_si128((__m128i *)op, r);
. ip += 8;
10,478 ( 0.17%) op += 16;
. }
14,104 ( 0.23%) if (ip >= end) break;
7,036 ( 0.11%) c = *ip;
21,108 ( 0.34%) if (c >= 0xD800 && c < 0xDC00) {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\nrun_lens=[]\ndef classify(c):\n if c<0x80: return 1\n if c<0x800: return 2\n if c<0xD800 or c>=0xE000: return 3\n return 4\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c=units[i]\n cls=classify(c)\n j=i\n if cls!=4:\n while j<len(units) and classify(units[j])==cls:\n j+=1\n run_lens.append((cls,j-i))\n i=j\n else:\n while j<len(units) and classify(units[j])==4:\n j+=2\n run_lens.append((4,(j-i)//2))\n i=j\nfrom collections import Counter\nc1 = [r for cls,r in run_lens if cls==1]\nimport statistics\nprint('ascii runs total units', sum(c1), 'count', len(c1))\nbuckets = Counter()\nfor r in c1:\n if r<8: buckets['<8']+=r\n else: buckets['>=8']+=r\nprint(buckets)\n\"\n"}
tool result
ascii runs total units 578313 count 21908
Counter({'>=8': 524070, '<8': 54243})
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\nrun_lens=[]\ndef classify(c):\n if c<0x80: return 1\n if c<0x800: return 2\n if c<0xD800 or c>=0xE000: return 3\n return 4\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c=units[i]\n cls=classify(c)\n j=i\n if cls!=4:\n while j<len(units) and classify(units[j])==cls:\n j+=1\n run_lens.append((cls,j-i))\n i=j\n else:\n while j<len(units) and classify(units[j])==4:\n j+=2\n run_lens.append((4,(j-i)//2))\n i=j\nfrom collections import Counter\nfor target in [2,3,4]:\n runs = [r for cls,r in run_lens if cls==target]\n buckets = Counter()\n for r in runs:\n if r<8: buckets['<8']+=r\n else: buckets['>=8']+=r\n print(target, 'total', sum(runs), buckets)\n\"\n"}
tool result
2 total 136813 Counter({'>=8': 120895, '<8': 15918})
3 total 186156 Counter({'>=8': 184794, '<8': 1362})
4 total 52401 Counter({'>=8': 35100, '<8': 17301})
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cat > /tmp/hybrid_test.c << 'EOF'\nEOF\n# Let's recreate the earlier failed hybrid quickly for inspection, in isolation from main solve.c\ncp /tmp/solve_final_ssse3.c /tmp/hybrid_solve.c\necho ok"}
tool result
ok
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && callgrind_annotate /tmp/cg_full.out 2>/dev/null | sed -n '120,180p'"}
tool result
. }
21,104 ( 0.34%) if (ip >= end) break;
10,543 ( 0.17%) c = *ip;
31,629 ( 0.52%) if (c >= 0x80 && c < 0x800) {
. do {
215,934 ( 3.52%) uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
35,989 ( 0.59%) memcpy(op, &v, 2);
35,989 ( 0.59%) op += 2;
35,989 ( 0.59%) ip++;
251,523 ( 4.10%) } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
. }
14,168 ( 0.23%) } else if (c < 0xDC00) {
21,252 ( 0.35%) if (ip + 1 >= end) return INVALID;
7,084 ( 0.12%) uint32_t lo = ip[1];
21,252 ( 0.35%) if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
63,214 ( 1.03%) while (ip + 8 <= end) {
. __m128i v = _mm_loadu_si128((const __m128i *)ip);
41,962 ( 0.68%) if (!all_surrogate_pairs(v)) break;
. __m128i r = encode4_pairs(v);
. _mm_storeu_si128((__m128i *)op, r);
. ip += 8;
10,478 ( 0.17%) op += 16;
. }
14,104 ( 0.23%) if (ip >= end) break;
7,036 ( 0.11%) c = *ip;
21,108 ( 0.34%) if (c >= 0xD800 && c < 0xDC00) {
. do {
20,978 ( 0.34%) if (ip + 1 >= end) return INVALID;
10,489 ( 0.17%) uint32_t lo2 = ip[1];
31,467 ( 0.51%) if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
41,956 ( 0.68%) uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
. uint32_t v = 0x808080F0u
20,978 ( 0.34%) | ((cp & 0x3F) << 24)
41,956 ( 0.68%) | (((cp >> 6) & 0x3F) << 16)
31,467 ( 0.51%) | (((cp >> 12) & 0x3F) << 8)
73,423 ( 1.20%) | (cp >> 18);
. memcpy(op, &v, 4);
10,489 ( 0.17%) op += 4;
10,489 ( 0.17%) ip += 2;
83,622 ( 1.36%) } while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
4,644 ( 0.08%) } else if (ip < end && c >= 0xDC00 && c < 0xE000) {
. return INVALID;
. }
. } else {
. return INVALID;
. }
. }
1,184 ( 0.02%) return (size_t)(op - out);
10,976 ( 0.18%) }
.
. #endif // UTF16_HAVE_SSE2
.
. // Portable scalar fallback (used when SSSE3 is unavailable at runtime, or on
. // non-x86 targets).
. static size_t utf16_to_utf8_scalar(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
. uint8_t *op = out;
. const uint16_t *ip = in;
-- line 250 ----------------------------------------
-- line 279 ----------------------------------------
. ip += 2;
. } else {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "grep -n \"} while (ip < end && (c = \\*ip) >= 0x80 && c < 0x800);\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
203: } while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nimport struct\nwith open('/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_1.bin','rb') as f:\n data=f.read()\noff=0\nrun_lens=[]\ndef classify(c):\n if c<0x80: return 1\n if c<0x800: return 2\n if c<0xD800 or c>=0xE000: return 3\n return 4\nwhile off+4<=len(data):\n cnt=struct.unpack('<I', data[off:off+4])[0]\n off+=4\n units=struct.unpack(f'<{cnt}H', data[off:off+2*cnt])\n off+=2*cnt\n i=0\n while i<len(units):\n c=units[i]\n cls=classify(c)\n j=i\n if cls!=4:\n while j<len(units) and classify(units[j])==cls:\n j+=1\n run_lens.append((cls,j-i))\n i=j\n else:\n while j<len(units) and classify(units[j])==4:\n j+=2\n run_lens.append((4,(j-i)//2))\n i=j\nimport statistics\nr2 = [r for cls,r in run_lens if cls==2]\nprint('count',len(r2),'median',statistics.median(r2))\nfrom collections import Counter\nprint(sorted(Counter(r2).items())[:20])\n\"\n"}
tool result
count 10552 median 10.0
[(1, 3), (2, 503), (3, 571), (4, 542), (5, 615), (6, 601), (7, 621), (8, 675), (9, 686), (10, 719), (11, 770), (12, 284), (13, 329), (14, 273), (15, 283), (16, 334), (17, 234), (18, 259), (19, 229), (20, 212)]
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\nfor f in ascii latin cjk emoji; do\n echo \"== $f ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgfin_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgfin_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii ==
2050217
== latin ==
8366653
== cjk ==
8891624
== emoji ==
12320871
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '205,230p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "python3 -c \"\nK = 0x10000 - (0xD800<<10) - 0xDC00\nprint(hex(K & 0xFFFFFFFF))\nc=0xD800+5\nlo=0xDC00+7\ncp1 = 0x10000 + ((c-0xD800)<<10) + (lo-0xDC00)\ncp2 = (c<<10) + lo + K\nprint(hex(cp1), hex(cp2 & 0xFFFFFFFF))\n\""}
tool result
0xfca02400
0x11407 0x11407
--- Command finished with exit code: 0 ---
assistant
We can simplify the scalar cp computation slightly. Let's apply this micro-opt to both scalar surrogate paths.
tool call: bash
{"command": "grep -n \"cp = 0x10000\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
224: uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);
271: uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && sed -i \\\n -e 's/uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo2 - 0xDC00);/uint32_t cp = (c << 10) + lo2 - 0x35FDC00u;/' \\\n -e 's/uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00);/uint32_t cp = (c << 10) + lo - 0x35FDC00u;/' \\\n submission/solve.c\npython3 -c \"\nprint(hex((0xD800<<10) + 0xDC00 - 0x10000))\n\""}
tool result
0x35fdc00
--- Command finished with exit code: 0 ---
assistant
Good, constant matches.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -20"}
tool result
33079855
--- Command finished with exit code: 0 ---
assistant
Small win (33.08M vs 33.13M). Let's grade.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS
measure 0.4s 33,079,855 instructions (given: 78,181,481)
SCORE +1.2409 (2.363x)
--- Command finished with exit code: 0 ---
assistant
Let's also apply similar simplification to the scalar fallback function for consistency (not perf critical but correctness matters).
tool call: bash
{"command": "grep -n \"cp = 0x10000\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
--- Command finished with exit code: 1 ---
Exit code: 1
assistant
Both already updated. Let's verify full gate and check remaining 2-byte scalar path for similar simplification.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full --seed 1 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS (FULL gate)
measure 0.4s 33,079,855 instructions (given: 78,181,481)
SCORE +1.2409 (2.363x)
--- Command finished with exit code: 0 ---
assistant
Let's try to reduce the ASCII scalar tail loop cost (the `do {} while` copying one byte at a time). Let's check if using memcpy of 2 units when exactly one unit remains under 8 might help, or unroll by 2.
tool call: bash
{"command": "sed -n '158,175p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c verify/runner.c -o /tmp/runner_cur -lm\nfor f in ascii latin cjk emoji; do\n echo \"== $f ==\"\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cgz_$f.out /tmp/runner_cur /tmp/corpus_$f.bin >/dev/null 2>&1\n grep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cgz_$f.out | awk '{s+=$2} END{print s}'\ndone"}
tool result
== ascii ==
2050217
== latin ==
8366653
== cjk ==
8891624
== emoji ==
12253721
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "objdump -d /tmp/runner_cur -M intel | awk '/<utf16_to_utf8_vec>:/{f=1} f' | sed -n '1,40p'"}
tool result
0000000000002980 <utf16_to_utf8_vec>:
2980: 48 89 f9 mov rcx,rdi
2983: 48 8d 3c 77 lea rdi,[rdi+rsi*2]
2987: 48 89 d6 mov rsi,rdx
298a: 48 39 f9 cmp rcx,rdi
298d: 0f 83 95 06 00 00 jae 3028 <utf16_to_utf8_vec+0x6a8>
2993: 66 45 0f 76 d2 pcmpeqd xmm10,xmm10
2998: 48 89 d0 mov rax,rdx
299b: 66 44 0f 6f 2d 6c 16 movdqa xmm13,XMMWORD PTR [rip+0x166c] # 4010 <_IO_stdin_used+0x10>
29a2: 00 00
29a4: 66 44 0f 6f 25 73 16 movdqa xmm12,XMMWORD PTR [rip+0x1673] # 4020 <_IO_stdin_used+0x20>
29ab: 00 00
29ad: 66 44 0f 6f 1d 7a 16 movdqa xmm11,XMMWORD PTR [rip+0x167a] # 4030 <_IO_stdin_used+0x30>
29b4: 00 00
29b6: 66 41 0f 72 d2 10 psrld xmm10,0x10
29bc: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
29c0: 0f b7 11 movzx edx,WORD PTR [rcx]
29c3: 83 fa 7f cmp edx,0x7f
29c6: 0f 86 14 01 00 00 jbe 2ae0 <utf16_to_utf8_vec+0x160>
29cc: 41 bb 80 00 80 00 mov r11d,0x800080
29d2: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800]
29d9: 66 41 0f 6e db movd xmm3,r11d
29de: 66 0f 70 db 00 pshufd xmm3,xmm3,0x0
29e3: 41 81 f8 ff 07 00 00 cmp r8d,0x7ff
29ea: 0f 86 d8 01 00 00 jbe 2bc8 <utf16_to_utf8_vec+0x248>
29f0: 81 fa ff 07 00 00 cmp edx,0x7ff
29f6: 0f 87 2c 04 00 00 ja 2e28 <utf16_to_utf8_vec+0x4a8>
29fc: 48 8d 51 10 lea rdx,[rcx+0x10]
2a00: 48 39 d7 cmp rdi,rdx
2a03: 0f 82 a4 00 00 00 jb 2aad <utf16_to_utf8_vec+0x12d>
2a09: b9 80 87 80 87 mov ecx,0x87808780
2a0e: 66 0f 76 d2 pcmpeqd xmm2,xmm2
2a12: 66 0f 6e e1 movd xmm4,ecx
2a16: b9 c0 00 c0 00 mov ecx,0xc000c0
2a1b: 66 0f 6f fa movdqa xmm7,xmm2
2a1f: 66 0f 6f f2 movdqa xmm6,xmm2
2a23: 66 0f 6e e9 movd xmm5,ecx
2a27: 66 0f 70 e4 00 pshufd xmm4,xmm4,0x0
2a2c: 66 0f 71 f7 07 psllw xmm7,0x7
2a31: 66 0f 71 f6 0f psllw xmm6,0xf
--- Command finished with exit code: 0 ---
assistant
This is already quite tight. Let's estimate total instruction breakdown and check overall for any low-hanging fruit remaining, particularly in the top-level dispatch overhead (function pointer / branch checking `have_ssse3`).
tool call: bash
{"command": "grep -n \"have_ssse3\\|utf16_to_utf8(const\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
287:size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {
289: static int have_ssse3 = -1;
290: if (have_ssse3 < 0) have_ssse3 = __builtin_cpu_supports("ssse3") ? 1 : 0;
291: if (have_ssse3) return utf16_to_utf8_vec(in, n, out);
--- Command finished with exit code: 0 ---
assistant
This dispatch overhead is per-call, negligible relative to per-corpus-record cost (592 records only). Let's do final check of scores across multiple seeds and lock this in.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && for s in 1 2 3 42 100 999; do ./grade --seed $s --quiet 2>&1 | tail -3; done"}
tool result
SCORE +1.2409 (2.363x)
SCORE +1.2473 (2.374x)
SCORE +1.2561 (2.389x)
SCORE +1.2383 (2.359x)
SCORE +1.2463 (2.372x)
SCORE +1.2429 (2.367x)
--- Command finished with exit code: 0 ---
assistant
Consistent ~1.24-1.26 across seeds (2.36-2.39x). Let's try a couple more optimizations before finalizing. Let's check if increasing 2-byte kernel unroll (interleave with pack) reduces per-unit cost, or try combining ASCII+2byte fast checks into single pass (rare, skip). Let's check if precomputing shuffle masks as static const (file scope) instead of local const reduces any redundant load/broadcasts per call.
tool call: bash
{"command": "sed -n '20,45p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
#ifdef UTF16_HAVE_SSE2
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
__m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
(char)1, (char)9, (char)0x80,
(char)2, (char)10, (char)0x80,
(char)3, (char)11, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
(char)0x80, (char)0x80, (char)1,
(char)0x80, (char)0x80, (char)2,
--- Command finished with exit code: 0 ---
assistant
These are already loaded as movdqa from .rodata inside the loop preheader (as seen in objdump: the constants are hoisted out of the loop already by GCC's LICM, loaded once before the loop). Good — no further win there.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | awk '/<utf16_to_utf8_vec>:/{f=1} f' | grep -c \"movdqa.*rip\""}
tool result
3
--- Command finished with exit code: 0 ---
assistant
Good, constants already hoisted. Let's check if `all_2byte`/`all_3byte`/`all_surrogate_pairs` masks could be combined with the encode computation to avoid redundant work (since encode already computes hi/mid/lo which overlaps with the range check).
tool call: bash
{"command": "sed -n '45,75p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
(char)0x80, (char)0x80, (char)2,
(char)0x80, (char)0x80, (char)3,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
(char)5, (char)13, (char)0x80,
(char)6, (char)14, (char)0x80,
(char)7, (char)15, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
(char)0x80, (char)0x80, (char)5,
(char)0x80, (char)0x80, (char)6,
(char)0x80, (char)0x80, (char)7,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
__m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
__m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
_mm_storeu_si128((__m128i *)(out + 0), lo4);
_mm_storeu_si128((__m128i *)(out + 12), hi4);
}
// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
static inline int all_3byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
__m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i bad = _mm_or_si128(lomask, surrmask);
return _mm_movemask_epi8(bad) == 0;
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '175,190p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cc -O2 -std=c17 -fno-lto -g -I submission submission/solve.c /tmp/asciitest.c -o /tmp/asciitest_v2\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/cg_asciimini2.out /tmp/asciitest_v2 >/dev/null 2>&1\ngrep -E \"^[0-9]+ [0-9]+$|^[0-9]+ [0-9]+ \" /tmp/cg_asciimini2.out | awk '{s+=$2} END{print s}'"}
tool result
2050217
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "sed -n '184,192p' /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
--- Command finished with exit code: 0 ---
assistant
At 200000 units, ASCII-only test gives 2050217 / 200000 ≈ 10.25 instructions/unit. Given the given implementation costs ~50 instr/unit, we're doing great here already. Let's check overall grade one final time and consider this largely converged. Let's try one more idea: combine `all_Xbyte` check and encode into a single pass where possible for 2-byte (currently separate calls, maybe fine due to inlining already).
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && objdump -d /tmp/runner_cur -M intel | awk '/<utf16_to_utf8_vec>:/{f=1} f' | sed -n '/2a0[0-9]:/,/jb.*2a[0-9a-f]/p' | head -60"}
tool result
2a00: 48 39 d7 cmp rdi,rdx
2a03: 0f 82 a4 00 00 00 jb 2aad <utf16_to_utf8_vec+0x12d>
2a09: b9 80 87 80 87 mov ecx,0x87808780
2a0e: 66 0f 76 d2 pcmpeqd xmm2,xmm2
2a12: 66 0f 6e e1 movd xmm4,ecx
2a16: b9 c0 00 c0 00 mov ecx,0xc000c0
2a1b: 66 0f 6f fa movdqa xmm7,xmm2
2a1f: 66 0f 6f f2 movdqa xmm6,xmm2
2a23: 66 0f 6e e9 movd xmm5,ecx
2a27: 66 0f 70 e4 00 pshufd xmm4,xmm4,0x0
2a2c: 66 0f 71 f7 07 psllw xmm7,0x7
2a31: 66 0f 71 f6 0f psllw xmm6,0xf
2a36: 66 0f 70 ed 00 pshufd xmm5,xmm5,0x0
2a3b: 66 0f 71 d2 0a psrlw xmm2,0xa
2a40: eb 3f jmp 2a81 <utf16_to_utf8_vec+0x101>
2a42: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0]
2a48: 66 0f 6f c8 movdqa xmm1,xmm0
2a4c: 66 0f db c2 pand xmm0,xmm2
2a50: 48 8d 4a 10 lea rcx,[rdx+0x10]
2a54: 48 83 c0 10 add rax,0x10
2a58: 66 0f 71 d1 06 psrlw xmm1,0x6
2a5d: 66 0f eb c3 por xmm0,xmm3
2a61: 66 0f eb cd por xmm1,xmm5
2a65: 66 0f 67 c0 packuswb xmm0,xmm0
2a69: 66 0f 67 c9 packuswb xmm1,xmm1
2a6d: 66 0f 60 c8 punpcklbw xmm1,xmm0
2a71: 0f 11 48 f0 movups XMMWORD PTR [rax-0x10],xmm1
2a75: 48 39 cf cmp rdi,rcx
2a78: 0f 82 72 05 00 00 jb 2ff0 <utf16_to_utf8_vec+0x670>
2a7e: 48 89 ca mov rdx,rcx
2a81: f3 0f 6f 42 f0 movdqu xmm0,XMMWORD PTR [rdx-0x10]
2a86: 66 44 0f 6f c4 movdqa xmm8,xmm4
2a8b: 66 0f 6f c8 movdqa xmm1,xmm0
2a8f: 66 0f fd cf paddw xmm1,xmm7
2a93: 66 0f ef ce pxor xmm1,xmm6
2a97: 66 44 0f 65 c1 pcmpgtw xmm8,xmm1
2a9c: 66 41 0f d7 c8 pmovmskb ecx,xmm8
2aa1: 81 f9 ff ff 00 00 cmp ecx,0xffff
2aa7: 74 9f je 2a48 <utf16_to_utf8_vec+0xc8>
2aa9: 48 8d 4a f0 lea rcx,[rdx-0x10]
2aad: 48 39 f9 cmp rcx,rdi
2ab0: 0f 83 c6 00 00 00 jae 2b7c <utf16_to_utf8_vec+0x1fc>
2ab6: 44 0f b7 01 movzx r8d,WORD PTR [rcx]
2aba: 41 8d 50 80 lea edx,[r8-0x80]
2abe: 81 fa 7f 07 00 00 cmp edx,0x77f
2ac4: 0f 86 cb 00 00 00 jbe 2b95 <utf16_to_utf8_vec+0x215>
2aca: 0f b7 11 movzx edx,WORD PTR [rcx]
2acd: 83 fa 7f cmp edx,0x7f
2ad0: 0f 87 f6 fe ff ff ja 29cc <utf16_to_utf8_vec+0x4c>
2ad6: 66 2e 0f 1f 84 00 00 cs nop WORD PTR [rax+rax*1+0x0]
2add: 00 00 00
2ae0: 4c 8d 41 10 lea r8,[rcx+0x10]
2ae4: 4c 39 c7 cmp rdi,r8
2ae7: 0f 82 4c 05 00 00 jb 3039 <utf16_to_utf8_vec+0x6b9>
2aed: 66 0f 76 d2 pcmpeqd xmm2,xmm2
2af1: 66 0f ef db pxor xmm3,xmm3
2af5: 66 0f 71 f2 07 psllw xmm2,0x7
2afa: eb 21 jmp 2b1d <utf16_to_utf8_vec+0x19d>
2afc: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
2b00: 66 0f 67 c0 packuswb xmm0,xmm0
--- Command finished with exit code: 0 ---
assistant
This is a very tight loop (about 15 instructions for 8 units of 2-byte encoding = ~1.9 instr/unit for hot path, plus check overhead). The code is well optimized. Let's do a final comprehensive check and wrap up.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full --seed 7 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS (FULL gate)
measure 1.3s 32,878,929 instructions (given: 77,781,994)
SCORE +1.2423 (2.366x)
--- Command finished with exit code: 0 ---
assistant
Let's try one more avenue: since 3-byte range is the largest fraction with long runs, let's try widening only that kernel to AVX2 but keep everything else SSSE3, and only use AVX2 when it actually helps (guard threshold via run detection isn't feasible cheaply, but let's re-test the earlier hybrid with the improved baseline).
tool call: bash
{"command": "cp /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c /tmp/solve_baseline_236.c\ncat /tmp/solve_baseline_236.c | grep -n \"^size_t utf16_to_utf8\\|^__attribute\" | head -5"}
tool result
26:__attribute__((target("ssse3")))
89:__attribute__((target("ssse3")))
142:__attribute__((target("ssse3")))
287:size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) {
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\npython3 - << 'EOF'\nimport re\nwith open('submission/solve.c') as f:\n content = f.read()\n\n# insert avx2 kernel + have_avx2 check, and modify 3-byte branch\navx2_block = '''\n#include <immintrin.h>\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_3byte16(__m256i v) {\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i lomask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(v, sbit));\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));\n __m256i surrmask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(shifted, sbit));\n __m256i bad = _mm256_or_si256(lomask, surrmask);\n return _mm256_movemask_epi8(bad) == 0;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_3byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));\n __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));\n mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n\n __m256i AB = _mm256_packus_epi16(hi, mid);\n __m256i C = _mm256_packus_epi16(lo, lo);\n\n const __m256i idxAB_lo = _mm256_setr_epi8(\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_lo = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxAB_hi = _mm256_setr_epi8(\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_hi = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n\n __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo));\n __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), _mm256_castsi256_si128(lo4));\n _mm_storeu_si128((__m128i *)(out + 12), _mm256_castsi256_si128(hi4));\n _mm_storeu_si128((__m128i *)(out + 24), _mm256_extracti128_si256(lo4, 1));\n _mm_storeu_si128((__m128i *)(out + 36), _mm256_extracti128_si256(hi4, 1));\n}\n\nstatic int g_have_avx2 = -1;\nstatic inline int have_avx2(void) {\n if (g_have_avx2 < 0) g_h
... [1492 characters truncated for page size]
tool result
done
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
submission/solve.c: In function ‘utf16_to_utf8’:
submission/solve.c:381:19: error: invalid storage class for function ‘all_3byte16’
381 | static inline int all_3byte16(__m256i v) {
| ^~~~~~~~~~~
submission/solve.c:395:20: error: invalid storage class for function ‘encode16_3byte’
395 | static inline void encode16_3byte(__m256i v, uint8_t *out) {
| ^~~~~~~~~~~~~~
submission/solve.c:445:19: error: invalid storage class for function ‘have_avx2’
445 | static inline int have_avx2(void) {
| ^~~~~~~~~
submission/solve.c:451:20: error: invalid storage class for function ‘run_3byte_avx2’
451 | static inline void run_3byte_avx2(const uint16_t **ipp, const uint16_t *end, uint8_t **opp) {
| ^~~~~~~~~~~~~~
--- Command finished with exit code: 0 ---
assistant
It got inserted in two places (both #ifdef occurrences?). Let me check.
tool call: bash
{"command": "grep -n \"#ifdef UTF16_HAVE_SSE2\\|all_3byte16\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
21:#ifdef UTF16_HAVE_SSE2
26:static inline int all_3byte16(__m256i v) {
101: if (!all_3byte16(v)) break;
376:#ifdef UTF16_HAVE_SSE2
381:static inline int all_3byte16(__m256i v) {
456: if (!all_3byte16(v)) break;
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cp /tmp/solve_baseline_236.c /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c\ngrep -n \"#ifdef UTF16_HAVE_SSE2\\|c >= 0x800 && (c < 0xD800\" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
21:#ifdef UTF16_HAVE_SSE2
168: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
178: if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
257: } else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
288:#ifdef UTF16_HAVE_SSE2
--- Command finished with exit code: 0 ---
assistant
Right, `#ifdef UTF16_HAVE_SSE2` appears once but `#endif` closes near line 244 then reappears at 288 for something else (must be `have_ssse3`). Let me check actual structure.
tool call: bash
{"command": "grep -n \"#ifdef\\|#endif\\|#if \" /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
15:#if defined(__x86_64__) || defined(__i386__)
19:#endif
21:#ifdef UTF16_HAVE_SSE2
244:#endif // UTF16_HAVE_SSE2
288:#ifdef UTF16_HAVE_SSE2
292:#endif
--- Command finished with exit code: 0 ---
assistant
I see, the python replace matched both occurrences of the pattern. Let me redo more carefully targeting only line 21.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode\npython3 - << 'PYEOF'\nwith open('submission/solve.c') as f:\n lines = f.readlines()\n\navx2_block = '''\n#include <immintrin.h>\n\n__attribute__((target(\"avx2\")))\nstatic inline int all_3byte16(__m256i v) {\n __m256i sbit = _mm256_set1_epi16((short)0x8000);\n __m256i lomask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(v, sbit));\n __m256i shifted = _mm256_sub_epi16(v, _mm256_set1_epi16((short)0xD800));\n __m256i surrmask = _mm256_cmpgt_epi16(\n _mm256_xor_si256(_mm256_set1_epi16((short)(0x800 ^ 0x8000)), sbit),\n _mm256_xor_si256(shifted, sbit));\n __m256i bad = _mm256_or_si256(lomask, surrmask);\n return _mm256_movemask_epi8(bad) == 0;\n}\n\n__attribute__((target(\"avx2\")))\nstatic inline void encode16_3byte(__m256i v, uint8_t *out) {\n __m256i hi = _mm256_and_si256(_mm256_srli_epi16(v, 12), _mm256_set1_epi16(0x0F));\n hi = _mm256_or_si256(hi, _mm256_set1_epi16(0x00E0));\n __m256i mid = _mm256_and_si256(_mm256_srli_epi16(v, 6), _mm256_set1_epi16(0x3F));\n mid = _mm256_or_si256(mid, _mm256_set1_epi16(0x0080));\n __m256i lo = _mm256_and_si256(v, _mm256_set1_epi16(0x3F));\n lo = _mm256_or_si256(lo, _mm256_set1_epi16(0x0080));\n\n __m256i AB = _mm256_packus_epi16(hi, mid);\n __m256i C = _mm256_packus_epi16(lo, lo);\n\n const __m256i idxAB_lo = _mm256_setr_epi8(\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0, (char)8, (char)0x80, (char)1, (char)9, (char)0x80,\n (char)2, (char)10, (char)0x80, (char)3, (char)11, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_lo = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)0, (char)0x80, (char)0x80, (char)1,\n (char)0x80, (char)0x80, (char)2, (char)0x80, (char)0x80, (char)3,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxAB_hi = _mm256_setr_epi8(\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)4, (char)12, (char)0x80, (char)5, (char)13, (char)0x80,\n (char)6, (char)14, (char)0x80, (char)7, (char)15, (char)0x80,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n const __m256i idxC_hi = _mm256_setr_epi8(\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80,\n (char)0x80, (char)0x80, (char)4, (char)0x80, (char)0x80, (char)5,\n (char)0x80, (char)0x80, (char)6, (char)0x80, (char)0x80, (char)7,\n (char)0x80, (char)0x80, (char)0x80, (char)0x80);\n\n __m256i lo4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_lo), _mm256_shuffle_epi8(C, idxC_lo));\n __m256i hi4 = _mm256_or_si256(_mm256_shuffle_epi8(AB, idxAB_hi), _mm256_shuffle_epi8(C, idxC_hi));\n\n _mm_storeu_si128((__m128i *)(out + 0), _mm256_castsi256_si128(lo4));\n _mm_storeu_si128((__m128i *)(out + 12), _mm256_castsi256_si128(hi4));\n _mm_storeu_si128((__m128i *)(out + 24), _mm256_extracti128_si256(lo4, 1));\n _mm_storeu_si128((__m128i *)(out + 36), _mm256_extracti128_si256(hi4, 1));\n}\n\nstatic int g_have_avx2 = -1;\nstatic inline int have_avx2(void) {\n if (g_have_avx2 < 0) g_have_avx2 = __builtin_cpu_supports(\"avx2\") ? 1 : 0;\n return g_have_
... [1634 characters truncated for page size]
tool result
occurrences: 1
done
--- Command finished with exit code: 0 ---
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh 2>&1 | tail -30"}
tool result
40677378
--- Command finished with exit code: 0 ---
assistant
Worse (40.7M vs 33.1M baseline), confirming AVX2 hybrid doesn't help here due to run-length mismatch and dispatch overhead. Revert to the SSSE3 baseline.
tool call: bash
{"command": "cp /tmp/solve_baseline_236.c /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c\ncd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && /tmp/iterate.sh"}
tool result
33079855
--- Command finished with exit code: 0 ---
assistant
Good, confirmed baseline restored. Let's finalize with a clean grade run and commit.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full 2>&1 | tail -10"}
tool result
build 0.7s
verify 1.9s PASS (FULL gate)
measure 1.3s 33,025,407 instructions (given: 78,125,653)
SCORE +1.2422 (2.366x)
--- Command finished with exit code: 0 ---
assistant
Let's check git status and commit.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && git status 2>&1 | head -20\ngit log --oneline -5 2>&1"}
tool result
fatal: not a git repository (or any of the parent directories): .git
fatal: not a git repository (or any of the parent directories): .git
--- Command finished with exit code: 128 ---
Exit code: 128
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode && git status 2>&1 | head -20"}
tool result
fatal: not a git repository (or any of the parent directories): .git
--- Command finished with exit code: 0 ---
assistant
No git repo here, so no commit needed for this bench task. Let's do final verification and view the final solve.c.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && cat submission/solve.c | wc -l\ntail -20 scores.jsonl"}
tool result
294
{"ts": "2026-07-19T03:44:01Z", "seed": 1, "cost": 34311457, "given_cost": 78181481, "score": 1.1881, "full_gate": false}
{"ts": "2026-07-19T03:48:26Z", "seed": 1, "cost": 45276604, "given_cost": 78181481, "score": 0.7881, "full_gate": false}
{"ts": "2026-07-19T03:50:37Z", "seed": 1, "cost": 34311457, "given_cost": 78181481, "score": 1.1881, "full_gate": false}
{"ts": "2026-07-19T03:52:19Z", "seed": 1, "cost": 34311457, "given_cost": 78181481, "score": 1.1881, "full_gate": false}
{"ts": "2026-07-19T03:54:17Z", "seed": 1, "cost": 33102083, "given_cost": 78181481, "score": 1.2399, "full_gate": false}
{"ts": "2026-07-19T03:56:15Z", "seed": 1, "cost": 33132300, "given_cost": 78181481, "score": 1.2386, "full_gate": false}
{"ts": "2026-07-19T03:56:22Z", "seed": 1, "cost": 33132300, "given_cost": 78181481, "score": 1.2386, "full_gate": true}
{"ts": "2026-07-19T03:56:26Z", "seed": 42, "cost": 32994570, "given_cost": 77692405, "score": 1.2355, "full_gate": false}
{"ts": "2026-07-19T03:56:30Z", "seed": 999, "cost": 33057291, "given_cost": 78113354, "score": 1.2406, "full_gate": false}
{"ts": "2026-07-19T03:58:26Z", "seed": 1, "cost": 33132300, "given_cost": 78181481, "score": 1.2386, "full_gate": false}
{"ts": "2026-07-19T04:01:34Z", "seed": 1, "cost": 33079855, "given_cost": 78181481, "score": 1.2409, "full_gate": false}
{"ts": "2026-07-19T04:01:43Z", "seed": 1, "cost": 33079855, "given_cost": 78181481, "score": 1.2409, "full_gate": true}
{"ts": "2026-07-19T04:02:28Z", "seed": 1, "cost": 33079855, "given_cost": 78181481, "score": 1.2409, "full_gate": false}
{"ts": "2026-07-19T04:02:32Z", "seed": 2, "cost": 32753220, "given_cost": 77756473, "score": 1.2473, "full_gate": false}
{"ts": "2026-07-19T04:02:36Z", "seed": 3, "cost": 32933402, "given_cost": 78662180, "score": 1.2561, "full_gate": false}
{"ts": "2026-07-19T04:02:39Z", "seed": 42, "cost": 32931673, "given_cost": 77692405, "score": 1.2383, "full_gate": false}
{"ts": "2026-07-19T04:02:43Z", "seed": 100, "cost": 32952617, "given_cost": 78173273, "score": 1.2463, "full_gate": false}
{"ts": "2026-07-19T04:02:46Z", "seed": 999, "cost": 33005336, "given_cost": 78113354, "score": 1.2429, "full_gate": false}
{"ts": "2026-07-19T04:04:22Z", "seed": 7, "cost": 32878929, "given_cost": 77781994, "score": 1.2423, "full_gate": true}
{"ts": "2026-07-19T04:06:00Z", "seed": 33956, "cost": 33025407, "given_cost": 78125653, "score": 1.2422, "full_gate": true}
--- Command finished with exit code: 0 ---
assistant
Final state is stable at score ≈ +1.24 (2.36-2.37x speedup), verified with full exhaustive gate on multiple seeds.
tool call: bash
{"command": "cat /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c"}
tool result
// solve.c — optimized utf16_to_utf8.
//
// Strategy: scalar loop with SSSE3-vectorized inner kernels for each of the
// four encoding classes (ASCII, 2-byte, 3-byte, surrogate-pair-to-4-byte).
// Each kernel processes 8 code units at a time as long as they all belong to
// the same class, falling back to a scalar loop at class boundaries and
// buffer tails. Falls back to a portable scalar implementation when SSE2 is
// unavailable (e.g. non-x86 builds), or when SSSE3 (pshufb) is unavailable.
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#define INVALID ((size_t)-1)
#if defined(__x86_64__) || defined(__i386__)
#include <emmintrin.h>
#include <tmmintrin.h>
#define UTF16_HAVE_SSE2 1
#endif
#ifdef UTF16_HAVE_SSE2
// Vectorized encode of 8 code units, all known to be in the "3-byte" range
// (0x0800-0xD7FF or 0xE000-0xFFFF), to 24 bytes of UTF-8 (packed as two
// 12-byte groups).
__attribute__((target("ssse3")))
static inline void encode8_3byte(__m128i v, uint8_t *out) {
__m128i hi = _mm_and_si128(_mm_srli_epi16(v, 12), _mm_set1_epi16(0x0F));
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00E0));
__m128i mid = _mm_and_si128(_mm_srli_epi16(v, 6), _mm_set1_epi16(0x3F));
mid = _mm_or_si128(mid, _mm_set1_epi16(0x0080));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i AB = _mm_packus_epi16(hi, mid); // bytes: hi0..hi7, mid0..mid7
__m128i C = _mm_packus_epi16(lo, lo); // bytes: lo0..lo7, lo0..lo7 (dup)
const __m128i idxAB_lo = _mm_setr_epi8((char)0, (char)8, (char)0x80,
(char)1, (char)9, (char)0x80,
(char)2, (char)10, (char)0x80,
(char)3, (char)11, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_lo = _mm_setr_epi8((char)0x80, (char)0x80, (char)0,
(char)0x80, (char)0x80, (char)1,
(char)0x80, (char)0x80, (char)2,
(char)0x80, (char)0x80, (char)3,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxAB_hi = _mm_setr_epi8((char)4, (char)12, (char)0x80,
(char)5, (char)13, (char)0x80,
(char)6, (char)14, (char)0x80,
(char)7, (char)15, (char)0x80,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
const __m128i idxC_hi = _mm_setr_epi8((char)0x80, (char)0x80, (char)4,
(char)0x80, (char)0x80, (char)5,
(char)0x80, (char)0x80, (char)6,
(char)0x80, (char)0x80, (char)7,
(char)0x80, (char)0x80, (char)0x80, (char)0x80);
__m128i lo4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_lo), _mm_shuffle_epi8(C, idxC_lo));
__m128i hi4 = _mm_or_si128(_mm_shuffle_epi8(AB, idxAB_hi), _mm_shuffle_epi8(C, idxC_hi));
_mm_storeu_si128((__m128i *)(out + 0), lo4);
_mm_storeu_si128((__m128i *)(out + 12), hi4);
}
// True iff all 8 code units in v are in [0x0800,0xD7FF] or [0xE000,0xFFFF].
static inline int all_3byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i lomask = _mm_cmplt_epi16(_mm_xor_si128(v, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0xD800));
__m128i surrmask = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x800 ^ 0x8000)));
__m128i bad = _mm_or_si128(lomask, surrmask);
return _mm_movemask_epi8(bad) == 0;
}
// True iff all 8 code units in v are in [0x0080,0x07FF].
static inline int all_2byte(__m128i v) {
__m128i sbit = _mm_set1_epi16((short)0x8000);
__m128i shifted = _mm_sub_epi16(v, _mm_set1_epi16((short)0x0080));
__m128i inrange = _mm_cmplt_epi16(_mm_xor_si128(shifted, sbit),
_mm_set1_epi16((short)(0x0780 ^ 0x8000)));
return _mm_movemask_epi8(inrange) == 0xFFFF;
}
// Vectorized encode of 8 code units, all known to be in [0x0080,0x07FF], to
// 16 bytes of UTF-8.
__attribute__((target("ssse3")))
static inline __m128i encode8_2byte(__m128i v) {
__m128i hi = _mm_srli_epi16(v, 6);
hi = _mm_or_si128(hi, _mm_set1_epi16(0x00C0));
__m128i lo = _mm_and_si128(v, _mm_set1_epi16(0x3F));
lo = _mm_or_si128(lo, _mm_set1_epi16(0x0080));
__m128i hib = _mm_packus_epi16(hi, hi);
__m128i lob = _mm_packus_epi16(lo, lo);
return _mm_unpacklo_epi8(hib, lob);
}
// v holds 4 packed 32-bit lanes, each (hi<<0)|(lo<<16) i.e. loaded from 4
// consecutive (high,low) surrogate pairs. True iff all 4 pairs are valid
// (hi in [0xD800,0xDBFF], lo in [0xDC00,0xDFFF]).
static inline int all_surrogate_pairs(__m128i v) {
__m128i sbit32 = _mm_set1_epi32((int)0x80000000u);
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
__m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
__m128i hi_ok = _mm_cmplt_epi32(_mm_xor_si128(hi_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i lo_ok = _mm_cmplt_epi32(_mm_xor_si128(lo_adj, sbit32),
_mm_set1_epi32((int)(0x400u ^ 0x80000000u)));
__m128i allok = _mm_and_si128(hi_ok, lo_ok);
return _mm_movemask_epi8(allok) == 0xFFFF;
}
// Vectorized encode of 4 valid surrogate pairs (packed as in
// all_surrogate_pairs) to 16 bytes of UTF-8 (4 bytes each).
static inline __m128i encode4_pairs(__m128i v) {
__m128i himask = _mm_set1_epi32(0xFFFF);
__m128i hi = _mm_and_si128(v, himask);
__m128i lo = _mm_srli_epi32(v, 16);
__m128i hi_adj = _mm_sub_epi32(hi, _mm_set1_epi32(0xD800));
__m128i lo_adj = _mm_sub_epi32(lo, _mm_set1_epi32(0xDC00));
__m128i cp = _mm_add_epi32(_mm_add_epi32(_mm_slli_epi32(hi_adj, 10), lo_adj),
_mm_set1_epi32(0x10000));
__m128i b0 = _mm_srli_epi32(cp, 18);
__m128i b1 = _mm_and_si128(_mm_srli_epi32(cp, 12), _mm_set1_epi32(0x3F));
__m128i b2 = _mm_and_si128(_mm_srli_epi32(cp, 6), _mm_set1_epi32(0x3F));
__m128i b3 = _mm_and_si128(cp, _mm_set1_epi32(0x3F));
__m128i word = _mm_set1_epi32((int)0x808080F0u);
word = _mm_or_si128(word, b0);
word = _mm_or_si128(word, _mm_slli_epi32(b1, 8));
word = _mm_or_si128(word, _mm_slli_epi32(b2, 16));
word = _mm_or_si128(word, _mm_slli_epi32(b3, 24));
return word;
}
__attribute__((target("ssse3")))
static size_t utf16_to_utf8_vec(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
__m128i hi = _mm_and_si128(v, _mm_set1_epi16((short)0xFF80));
if (_mm_movemask_epi8(_mm_cmpeq_epi8(hi, _mm_setzero_si128())) != 0xFFFF)
break;
__m128i packed = _mm_packus_epi16(v, v);
_mm_storel_epi64((__m128i *)op, packed);
ip += 8;
op += 8;
}
if (ip >= end) break;
c = *ip;
if (c < 0x80) {
do {
*op++ = (uint8_t)c;
ip++;
} while (ip < end && (c = *ip) < 0x80);
}
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_3byte(v)) break;
encode8_3byte(v, op);
ip += 8;
op += 24;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
do {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} while (ip < end && (c = *ip) >= 0x800 && (c < 0xD800 || c >= 0xE000));
}
} else if (c < 0x800) {
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_2byte(v)) break;
__m128i r = encode8_2byte(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0x80 && c < 0x800) {
do {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} while (ip < end && (c = *ip) >= 0x80 && c < 0x800);
}
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
while (ip + 8 <= end) {
__m128i v = _mm_loadu_si128((const __m128i *)ip);
if (!all_surrogate_pairs(v)) break;
__m128i r = encode4_pairs(v);
_mm_storeu_si128((__m128i *)op, r);
ip += 8;
op += 16;
}
if (ip >= end) break;
c = *ip;
if (c >= 0xD800 && c < 0xDC00) {
do {
if (ip + 1 >= end) return INVALID;
uint32_t lo2 = ip[1];
if (lo2 < 0xDC00 || lo2 >= 0xE000) return INVALID;
uint32_t cp = (c << 10) + lo2 - 0x35FDC00u;
uint32_t v = 0x808080F0u
| ((cp & 0x3F) << 24)
| (((cp >> 6) & 0x3F) << 16)
| (((cp >> 12) & 0x3F) << 8)
| (cp >> 18);
memcpy(op, &v, 4);
op += 4;
ip += 2;
} while (ip + 1 < end && (c = *ip) >= 0xD800 && c < 0xDC00);
} else if (ip < end && c >= 0xDC00 && c < 0xE000) {
return INVALID;
}
} else {
return INVALID;
}
}
return (size_t)(op - out);
}
#endif // UTF16_HAVE_SSE2
// Portable scalar fallback (used when SSSE3 is unavailable at runtime, or on
// non-x86 targets).
static size_t utf16_to_utf8_scalar(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {
uint8_t *op = out;
const uint16_t *ip = in;
const uint16_t *end = in + n;
while (ip < end) {
uint32_t c = *ip;
if (c < 0x80) {
*op++ = (uint8_t)c;
ip++;
} else if (c >= 0x800 && (c < 0xD800 || c >= 0xE000)) {
uint32_t v = 0x008080E0u | ((c & 0x3F) << 16) | (((c >> 6) & 0x3F) << 8) | (c >> 12);
memcpy(op, &v, 4);
op += 3;
ip++;
} else if (c < 0x800) {
uint32_t v = 0x000080C0u | ((c & 0x3F) << 8) | (c >> 6);
memcpy(op, &v, 2);
op += 2;
ip++;
} else if (c < 0xDC00) {
if (ip + 1 >= end) return INVALID;
uint32_t lo = ip[1];
if (lo < 0xDC00 || lo >= 0xE000) return INVALID;
uint32_t cp = (c << 10) + lo - 0x35FDC00u;
... [709 characters truncated for page size]
assistant
The implementation is finalized and clean. Let's do one final grade run to confirm the recorded state.
tool call: bash
{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-utf16-transcode/tasks/utf16-transcode && ./grade --full 2>&1 | tail -10"}
tool result
build 0.7s
verify 2.0s PASS (FULL gate)
measure 1.3s 32,815,653 instructions (given: 77,774,485)
SCORE +1.2449 (2.370x)
--- Command finished with exit code: 0 ---
assistant
## Summary
Final score: **+1.24** (≈2.37x speedup over the given implementation), verified with the full exhaustive gate across multiple random seeds.
Key optimizations applied to `submission/solve.c`:
1. Replaced index-based scalar loop with pointer-based loop and `restrict` qualifiers.
2. Branchless byte construction using bit-packed `uint32_t` writes via `memcpy` instead of sequential byte stores.
3. Class-run batching: process consecutive runs of same-width code units together instead of re-evaluating branches every unit.
4. SSSE3-vectorized kernels processing 8 code units at a time for each encoding class:
- ASCII → 8 bytes via `packus`
- 2-byte (Latin/Cyrillic) → 16 bytes via shift/mask/interleave
- 3-byte (CJK) → 24 bytes via `pshufb`-based byte shuffling
- Surrogate pairs → 16 bytes (4 code points) via 32-bit lane arithmetic
5. Marked the vectorized function `target("ssse3")` (not just helpers) so kernels inline into the main loop instead of being called out-of-line.
6. Simplified surrogate codepoint arithmetic to a single shift+add+constant.
7. Runtime CPU dispatch (`__builtin_cpu_supports`) with a portable scalar fallback for non-SSSE3/non-x86 targets, preserving correctness everywhere.
I tried AVX2 (16-wide) kernels too, but the corpus's average run lengths per class are short enough that AVX2's setup/dispatch overhead made it net negative versus the 8-wide SSSE3 kernels, so I reverted to the SSSE3-only version, which was the actual best measured result.
assistant (final)
Good, AVX2 works under callgrind (Valgrind supports AVX2 emulation on this host CPU which has avx512). Let's check if valgrind supports AVX-512 too, but AVX2 is likely plenty. Let's design a vectorized implementation.Better than given already. Let's run grade and continue optimizing.Formulas check out. Now let's test.Nice, improvement. Let's verify correctness and grade.Improvement! Let's grade.Big improvement. Let's grade.Let's now vectorize the 3-byte (CJK) path too, since it's the dominant cost.The vectorized 3-byte encoding for 4 units works. Now let's integrate this into solve.c with proper validity range checks (0x800-0xD7FF, 0xE000-0xFFFF).Now let's check we can detect "all 8 units in valid 3-byte range" with a fast mask test.Both mask check and encode work with pure SSE2/SSSE3. Let's integrate into solve.c.Need target attribute or -mssse3 flag. Since grade uses fixed CFLAGS without -mssse3, need `__attribute__((target("ssse3")))`.Now I need to check where all_3byte and encode8_3byte and the main function need target attribute too since they call ssse3 intrinsics indirectly. Let's also add target to utf16_to_utf8 itself for the whole function, and check all_3byte only needs SSE2.Compiles now. Let's grade for correctness first.Excellent progress. Let's continue profiling.The bit was off since 0xC0 should be OR'd as low bits not high (packus truncates to unsigned bytes correctly with lower bits). Now integrate this into solve.c for the 2-byte path.Now update the 2-byte encoding path in the main loop to use this vectorized version.2x already. Let's keep going: try vectorizing the surrogate/emoji path and improve tail handling.That works. Now integrate this into solve.c for the surrogate-pair emoji path.Now update the surrogate handling branch to try vectorized batch processing when we hit a high surrogate.2.2x. Let's check the "else if (ip < end && c >= 0xDC00...)" branch is correct - actually this checks after loop broke, but is that even reachable properly? Let's verify full gate and continue profiling.Good, full gate passes. Let's check for edge case: c after break from vectorized loop might be in DC00-E000 range but that path is unreachable given the outer condition c<0xDC00 already established. Let's simplify/verify.This avoids the shift+repack step (fewer instructions: no srli_si128 + extra packus). Let's replace encode8_3byte with this simpler version.Let's now try widening to AVX2 (32-byte loads = 16 units at once) to halve loop overhead further.Need to wrap main's loop body calling avx2 intrinsics in a target-tagged function too, since `main` itself is baseline. Let's just add target to main for this test, but for solve.c we'd add target to utf16_to_utf8 itself.Let's build the full AVX2 version, testing correctness carefully. This is a fair bit of work but should give more speedup. Let's do it methodically.Now the surrogate pairs for AVX2 (8 pairs = 16 units at once):All AVX2 kernels validated. Now integrate into solve.c, using runtime CPU dispatch since AVX2 isn't guaranteed on all machines (need `__builtin_cpu_supports` to keep correctness gate safe, but the grading machine has AVX2 per earlier check). Let's check if we can just use target attribute per-function without ifunc, applied on whole file build with -O2 (no -mavx2 flag) — should work via target attributes only.Let's save this as v_ssse3 backup, then build the AVX2 version.Good, mostly inlined. Now let's write the AVX2 version. I'll check whether runtime dispatch is needed, since the grading corpus is measured on this same machine which supports AVX2.AVX2 version scored lower than SSSE3-only version. Let's investigate before deciding.The AVX2 version regressed due to shorter run lengths in the actual corpus (CJK/emoji bursts are much shorter than 16 units, so the 16-wide vectorized path rarely triggers, wasting setup). Let's revert to SSSE3 and then try a hybrid: AVX2 only for ASCII (which has long runs), SSSE3 (8-wide) for everything else.3-byte (CJK) runs are the longest (79% >= 16 units). Let's add a 16-wide AVX2 fast path specifically for the 3-byte range, keeping SSSE3 (8-wide) elsewhere.Let's add AVX2 3-byte kernel and use it with a 16-wide loop, falling back to the 8-wide SSSE3 loop for the tail.Now update the 3-byte branch in the main loop to try the 16-wide AVX2 path first when available.I need to wrap this inner block in an avx2-tagged helper function since the outer function isn't tagged.Worse than pure SSSE3 (34.3M). The have_avx2() branch check adds overhead each time entering the 3-byte state. Let's check per-corpus.Good, we're back to the 2.279x score baseline. Let's keep pushing SSSE3-only optimizations further. Let's profile the current best in detail.Good, back to the clean version. Let's look at the tail-handling logic to see if there's redundant work — after breaking out of vectorized loop, we recompute `c = *ip` and re-check condition unnecessarily but it's cheap. Let's check the main loop structure for the biggest remaining cost centers.This is fairly efficient already. Let's check how the tail scalar handling for the CJK path might be improved, since we're at diminishing returns for the vectorized bulk portion. Let's see the assembly loop structure for the 3-byte hot path itself.This is already tight (~20 instructions for encoding 8 units into 24 bytes). Let's check if idxAB constants being loaded from memory each call could be hoisted—since they're local `const` they get reloaded from .rodata each call, but compiler seems to keep them as constants loaded once per call (not per-iteration overhead beyond mov). Let's check the calling loop.Key insight: `encode8_3byte` is `target("ssse3")` but is called from the default-target main function, so it isn't inlined (we saw a `call` instruction). Let's mark the whole `utf16_to_utf8` function `target("ssse3")` to allow inlining.Improvement from inlining!Let's add a safe fallback path for portability, keeping performance intact.Let's add architecture portability guards for safety, falling back to scalar on non-x86.Slight overhead from the extra function-pointer dispatch check but negligible, and now safer/portable. Let's run the full gate to be sure and check a couple more random seeds.Consistent ~2.36x across seeds. Let's try to squeeze more. Let's check the ASCII path bulk copy since it seems well optimized, and look at ways to widen the surrogate-pair kernel handling since it's still notably costly.Both inlined into the loop (no standalone symbols now). Let's disasm the emoji-processing part of the loop.This is quite good. Let's compute the overall score once more, and try a couple micro-optimizations: combine the "all_2byte" check with encode inline (already done), check if branch order matters (put the most common branch first).This computes packus even when it might not be used, but it's cheap (both branches are computed unconditionally with no extra load). Let's try replacing the 8-wide ASCII loop with a 16-wide SSE2 loop (only needs SSE2, no SSSE3 needed) to halve loop overhead there since ASCII is 60% of units.Slightly worse (33.26M vs 33.13M). The extra 16-wide path adds overhead without benefit here. Let's revert that change.Good, back to baseline. Let's try one more thing: reorder branch checks by putting the most common ASCII check first (already first) but try reordering 2-byte/3-byte order since 3-byte(19.5%) > 2-byte(14.3%).Already 3-byte before 2-byte. Good. Let's check verify pass and try a few more corpus seeds to check stability, then consider this near final. Let's also try increasing kernel width for 2-byte and pair paths using AVX2 (since those are shorter runs, might not help, but let's just verify with actual measurements rather than assumptions).We can simplify the scalar cp computation slightly. Let's apply this micro-opt to both scalar surrogate paths.Good, constant matches.Small win (33.08M vs 33.13M). Let's grade.Let's also apply similar simplification to the scalar fallback function for consistency (not perf critical but correctness matters).Both already updated. Let's verify full gate and check remaining 2-byte scalar path for similar simplification.Let's try to reduce the ASCII scalar tail loop cost (the `do {} while` copying one byte at a time). Let's check if using memcpy of 2 units when exactly one unit remains under 8 might help, or unroll by 2.This is already quite tight. Let's estimate total instruction breakdown and check overall for any low-hanging fruit remaining, particularly in the top-level dispatch overhead (function pointer / branch checking `have_ssse3`).This dispatch overhead is per-call, negligible relative to per-corpus-record cost (592 records only). Let's do final check of scores across multiple seeds and lock this in.Consistent ~1.24-1.26 across seeds (2.36-2.39x). Let's try a couple more optimizations before finalizing. Let's check if increasing 2-byte kernel unroll (interleave with pack) reduces per-unit cost, or try combining ASCII+2byte fast checks into single pass (rare, skip). Let's check if precomputing shuffle masks as static const (file scope) instead of local const reduces any redundant load/broadcasts per call.These are already loaded as movdqa from .rodata inside the loop preheader (as seen in objdump: the constants are hoisted out of the loop already by GCC's LICM, loaded once before the loop). Good — no further win there.Good, constants already hoisted. Let's check if `all_2byte`/`all_3byte`/`all_surrogate_pairs` masks could be combined with the encode computation to avoid redundant work (since encode already computes hi/mid/lo which overlaps with the range check).At 200000 units, ASCII-only test gives 2050217 / 200000 ≈ 10.25 instructions/unit. Given the given implementation costs ~50 instr/unit, we're doing great here already. Let's check overall grade one final time and consider this largely converged. Let's try one more idea: combine `all_Xbyte` check and encode into a single pass where possible for 2-byte (currently separate calls, maybe fine due to inlining already).This is a very tight loop (about 15 instructions for 8 units of 2-byte encoding = ~1.9 instr/unit for hot path, plus check overhead). The code is well optimized. Let's do a final comprehensive check and wrap up.Let's try one more avenue: since 3-byte range is the largest fraction with long runs, let's try widening only that kernel to AVX2 but keep everything else SSSE3, and only use AVX2 when it actually helps (guard threshold via run detection isn't feasible cheaply, but let's re-test the earlier hybrid with the improved baseline).It got inserted in two places (both #ifdef occurrences?). Let me check.Right, `#ifdef UTF16_HAVE_SSE2` appears once but `#endif` closes near line 244 then reappears at 288 for something else (must be `have_ssse3`). Let me check actual structure.I see, the python replace matched both occurrences of the pattern. Let me redo more carefully targeting only line 21.Worse (40.7M vs 33.1M baseline), confirming AVX2 hybrid doesn't help here due to run-length mismatch and dispatch overhead. Revert to the SSSE3 baseline.Good, confirmed baseline restored. Let's finalize with a clean grade run and commit.Let's check git status and commit.No git repo here, so no commit needed for this bench task. Let's do final verification and view the final solve.c.Final state is stable at score ≈ +1.24 (2.36-2.37x speedup), verified with full exhaustive gate on multiple seeds.The implementation is finalized and clean. Let's do one final grade run to confirm the recorded state.## Summary
Final score: **+1.24** (≈2.37x speedup over the given implementation), verified with the full exhaustive gate across multiple random seeds.
Key optimizations applied to `submission/solve.c`:
1. Replaced index-based scalar loop with pointer-based loop and `restrict` qualifiers.
2. Branchless byte construction using bit-packed `uint32_t` writes via `memcpy` instead of sequential byte stores.
3. Class-run batching: process consecutive runs of same-width code units together instead of re-evaluating branches every unit.
4. SSSE3-vectorized kernels processing 8 code units at a time for each encoding class:
- ASCII → 8 bytes via `packus`
- 2-byte (Latin/Cyrillic) → 16 bytes via shift/mask/interleave
- 3-byte (CJK) → 24 bytes via `pshufb`-based byte shuffling
- Surrogate pairs → 16 bytes (4 code points) via 32-bit lane arithmetic
5. Marked the vectorized function `target("ssse3")` (not just helpers) so kernels inline into the main loop instead of being called out-of-line.
6. Simplified surrogate codepoint arithmetic to a single shift+add+constant.
7. Runtime CPU dispatch (`__builtin_cpu_supports`) with a portable scalar fallback for non-SSSE3/non-x86 targets, preserving correctness everywhere.
I tried AVX2 (16-wide) kernels too, but the corpus's average run lengths per class are short enough that AVX2's setup/dispatch overhead made it net negative versus the 8-wide SSSE3 kernels, so I reverted to the SSSE3-only version, which was the actual best measured result.