jcode + Claude Fable 5 on utf16-transcode

{"file_path": "spec.md"}

1 # utf16-transcode 2 3 Convert UTF-16LE to UTF-8. This is the boundary between JavaScript, Windows, and 4 Java on one side and the rest of the world on the other: every string crossing it 5 pays this function. 6 7 ## Task 8 9 You are given a working, tested implementation in `submission/solve.c`. 10 Make it faster. Correctness on every input is the gate, verified exhaustively 11 over all code units and pairs plus deep seeded coverage. 12 13 ``` 14 ./grade # build, verify, measure, score 15 ./grade --seed N # reproduce a specific cost corpus 16 ``` 17 18 Edit only files under `submission/`. 19 20 ## Contract 21 22 ```c 23 // Transcode UTF-16LE code units to UTF-8. 24 // in: code units, n: count. out: buffer, capacity >= 3*n+4 bytes. 25 // Returns bytes written, or (size_t)-1 if the input is invalid UTF-16 26 // (lone surrogate anywhere). 27 size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out); 28 ``` 29 30 Semantics: 31 32 - Code units 0x0000-0xD7FF and 0xE000-0xFFFF encode as 1-3 UTF-8 bytes. 33 - A high surrogate 0xD800-0xDBFF must be immediately followed by a low 34 surrogate 0xDC00-0xDFFF; the pair encodes one supplementary code point as 35 4 bytes. Anything else (lone high, lone low, high at end of input) is 36 invalid: return (size_t)-1. 37 - On invalid input the output buffer contents are unspecified. 38 39 ## Verification (the gate) 40 41 1. Every single code unit (65,536 cases). 42 2. Every pair of code units (4.3 billion pairs is too many: all pairs from a 43 2,namespace-stratified 4,096-unit sample = 16.7M pairs covering every 44 boundary class x class combination, plus all 2^20 surrogate x surrogate 45 pairs exactly). 46 3. Every code unit embedded at positions 0,1,2,3 in valid padding. 47 4. 200,000 seeded random strings (1-2K units) mixing ASCII runs, BMP text, 48 surrogate pairs, and injected lone surrogates. 49 50 Any mismatch against the reference oracle fails the grade with a counterexample. 51 52 ## Cost model (the score) 53 54 Instructions inside `utf16_to_utf8` (callgrind) over a seeded ~1M-unit corpus: 55 ASCII-heavy 40%, Latin/Cyrillic mix 25%, CJK-heavy 20%, emoji/supplementary 15%. 56 Paired against the frozen given implementation on the same corpus. 57 58 ``` 59 score = log2(given_cost / your_cost) 60 ``` 61 62 ## Rules 63 64 - Self-contained C17, libc only. 65 - Do not modify the grader/verifier. Any correct program is a valid submission.

{"command": "ls -la; ls submission"}

total 4 drwxr-xr-x 1 root root 160 Jul 19 02:36 . drwxr-xr-x 1 root root 60 Jul 19 02:36 .. drwxr-xr-x 1 root root 180 Jul 19 02:36 .build -rwxr-xr-x 1 root root 227 Jul 19 02:28 grade -rw-r--r-- 1 root root 122 Jul 19 02:36 scores.jsonl -rw-r--r-- 1 root root 2286 Jul 19 02:28 spec.md drwxr-xr-x 1 root root 60 Jul 19 02:28 submission drwxr-xr-x 1 root root 140 Jul 19 02:28 verify solve.c --- Command finished with exit code: 0 ---

{"file_path": "submission/solve.c"}

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. 4 #include <stdint.h> 5 #include <stddef.h> 6 7 #define INVALID ((size_t)-1) 8 9 size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) { 10 size_t o = 0; 11 for (size_t i = 0; i < n; i++) { 12 uint32_t c = in[i]; 13 if (c < 0x80) { 14 out[o++] = (uint8_t)c; 15 } else if (c < 0x800) { 16 out[o++] = (uint8_t)(0xC0 | (c >> 6)); 17 out[o++] = (uint8_t)(0x80 | (c & 0x3F)); 18 } else if (c < 0xD800 || c >= 0xE000) { 19 out[o++] = (uint8_t)(0xE0 | (c >> 12)); 20 out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F)); 21 out[o++] = (uint8_t)(0x80 | (c & 0x3F)); 22 } else if (c < 0xDC00) { 23 // high surrogate: need a low surrogate next 24 if (i + 1 >= n) return INVALID; 25 uint32_t lo = in[i + 1]; 26 if (lo < 0xDC00 || lo >= 0xE000) return INVALID; 27 i++; 28 uint32_t cp = 0x10000 + ((c - 0xD800) << 10) + (lo - 0xDC00); 29 out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 30 out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 31 out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 32 out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 33 } else { 34 return INVALID; // lone low surrogate 35 } 36 } 37 return o; 38 }

{"command": "cat grade; ls verify .build; cat scores.jsonl"}

#!/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") .build: callgrind.runner.out callgrind.runner_given.out corpus_28599.bin given_cost_28599.json runner runner_given verify verify: gen_corpus.py given.c reference.c runner.c verify.c {"ts": "2026-07-19T02:36:42Z", "seed": 28599, "cost": 77897475, "given_cost": 77897475, "score": 0.0, "full_gate": false} --- Command finished with exit code: 0 ---

{"command": "cat verify/runner.c; sed -n 1,80p ../../harness/grade.py 2>/dev/null || find / -name grade.py -path '*harness*' 2>/dev/null | head"}

// 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; } #!/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}?)") --- Command finished with exit code: 0 ---

{"command": "cat verify/gen_corpus.py | head -80; sed -n 80,140p ../../harness/grade.py"}

#!/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() 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 ---

{"command": "grep -o 'avx2\\|avx512[a-z]*\\|ssse3\\|sse4_2\\|bmi2' /proc/cpuinfo | sort -u; valgrind --version; cc --version | head -1"}

avx2 avx512 avx512bw avx512cd avx512dq avx512f avx512vbmi avx512vl bmi2 sse4_2 ssse3 valgrind-3.25.1 cc (GCC) 16.1.1 20260625 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t.c <<'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vbmi,avx512vl\")))\nint test512(void){ volatile __m512i a = _mm512_set1_epi16(3); __m512i b=_mm512_add_epi16(a,a); return _mm_cvtsi128_si32(_mm512_castsi512_si128(b)); }\n__attribute__((target(\"avx2\")))\nint test2(void){ volatile __m256i a=_mm256_set1_epi16(5); __m256i b=_mm256_add_epi16(a,a); return _mm_cvtsi128_si32(_mm256_castsi256_si128(b)); }\nint main(){\n printf(\"cpu avx2=%d avx512bw=%d avx512vbmi=%d\\n\", __builtin_cpu_supports(\"avx2\"), __builtin_cpu_supports(\"avx512bw\"), __builtin_cpu_supports(\"avx512vbmi\"));\n printf(\"avx2 result %d\\n\", test2());\n if(__builtin_cpu_supports(\"avx512bw\")) printf(\"avx512 result %d\\n\", test512());\n return 0;\n}\nEOF\ncc -O2 /tmp/t.c -o /tmp/t && /tmp/t && valgrind --tool=callgrind --callgrind-out-file=/dev/null /tmp/t 2>&1 | tail -5"}

cpu avx2=1024 avx512bw=2097152 avx512vbmi=67108864 avx2 result 655370 avx512 result 393222 ==170== ==170== Events : Ir ==170== Collected : 129384 ==170== ==170== I refs: 129,384 --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --callgrind-out-file=/dev/null /tmp/t 2>/dev/null"}

cpu avx2=1024 avx512bw=0 avx512vbmi=0 avx2 result 655370 --- Command finished with exit code: 0 ---

{"command": "cat verify/given.c | head -50; echo ---; cat verify/verify.c | head -60"}

// 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; } --- // 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 ---

{"command": "curl -s --max-time 15 https://raw.githubusercontent.com/simdutf/simdutf/master/src/haswell/avx2_convert_utf16_to_utf8.cpp -o /tmp/simdutf_avx2.cpp && wc -l /tmp/simdutf_avx2.cpp || echo NO_NET"}

602 /tmp/simdutf_avx2.cpp --- Command finished with exit code: 0 ---

{"file_path": "/tmp/simdutf_avx2.cpp"}

1 /* 2 The vectorized algorithm works on single SSE register i.e., it 3 loads eight 16-bit code units. 4 5 We consider three cases: 6 1. an input register contains no surrogates and each value 7 is in range 0x0000 .. 0x07ff. 8 2. an input register contains no surrogates and values are 9 is in range 0x0000 .. 0xffff. 10 3. an input register contains surrogates --- i.e. codepoints 11 can have 16 or 32 bits. 12 13 Ad 1. 14 15 When values are less than 0x0800, it means that a 16-bit code unit 16 can be converted into: 1) single UTF8 byte (when it is an ASCII 17 char) or 2) two UTF8 bytes. 18 19 For this case we do only some shuffle to obtain these 2-byte 20 codes and finally compress the whole SSE register with a single 21 shuffle. 22 23 We need 256-entry lookup table to get a compression pattern 24 and the number of output bytes in the compressed vector register. 25 Each entry occupies 17 bytes. 26 27 Ad 2. 28 29 When values fit in 16-bit code units, but are above 0x07ff, then 30 a single word may produce one, two or three UTF8 bytes. 31 32 We prepare data for all these three cases in two registers. 33 The first register contains lower two UTF8 bytes (used in all 34 cases), while the second one contains just the third byte for 35 the three-UTF8-bytes case. 36 37 Finally these two registers are interleaved forming eight-element 38 array of 32-bit values. The array spans two SSE registers. 39 The bytes from the registers are compressed using two shuffles. 40 41 We need 256-entry lookup table to get a compression pattern 42 and the number of output bytes in the compressed vector register. 43 Each entry occupies 17 bytes. 44 45 46 To summarize: 47 - We need two 256-entry tables that have 8704 bytes in total. 48 */ 49 50 /* 51 Returns a pair: the first unprocessed byte from buf and utf8_output 52 A scalar routing should carry on the conversion of the tail. 53 */ 54 template <endianness big_endian> 55 std::pair<const char16_t *, char *> 56 avx2_convert_utf16_to_utf8(const char16_t *buf, size_t len, char *utf8_output) { 57 const char16_t *end = buf + len; 58 const __m256i v_0000 = _mm256_setzero_si256(); 59 const __m256i v_f800 = _mm256_set1_epi16((int16_t)0xf800); 60 const __m256i v_d800 = _mm256_set1_epi16((int16_t)0xd800); 61 const __m256i v_c080 = _mm256_set1_epi16((int16_t)0xc080); 62 const size_t safety_margin = 63 12; // to avoid overruns, see issue 64 // https://github.com/simdutf/simdutf/issues/92 65 66 while (end - buf >= std::ptrdiff_t(16 + safety_margin)) { 67 __m256i in = _mm256_loadu_si256((__m256i *)buf); 68 if (big_endian) { 69 const __m256i swap = _mm256_setr_epi8( 70 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 17, 16, 19, 18, 71 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30); 72 in = _mm256_shuffle_epi8(in, swap); 73 } 74 // a single 16-bit UTF-16 word can yield 1, 2 or 3 UTF-8 bytes 75 const __m256i v_ff80 = _mm256_set1_epi16((int16_t)0xff80); 76 if (_mm256_testz_si256(in, v_ff80)) { // ASCII fast path!!!! 77 // 1. pack the bytes 78 const __m128i utf8_packed = _mm_packus_epi16( 79 _mm256_castsi256_si128(in), _mm256_extractf128_si256(in, 1)); 80 // 2. store (16 bytes) 81 _mm_storeu_si128((__m128i *)utf8_output, utf8_packed); 82 // 3. adjust pointers 83 buf += 16; 84 utf8_output += 16; 85 continue; // we are done for this round! 86 } 87 // no bits set above 7th bit 88 const __m256i one_byte_bytemask = 89 _mm256_cmpeq_epi16(_mm256_and_si256(in, v_ff80), v_0000); 90 const uint32_t one_byte_bitmask = 91 static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask)); 92 93 // no bits set above 11th bit 94 const __m256i one_or_two_bytes_bytemask = 95 _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_0000); 96 const uint32_t one_or_two_bytes_bitmask = 97 static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask)); 98 if (one_or_two_bytes_bitmask == 0xffffffff) { 99 100 // 1. prepare 2-byte values 101 // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8 102 // expected output : [110a|aaaa|10bb|bbbb] x 8 103 const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00); 104 const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f); 105 106 // t0 = [000a|aaaa|bbbb|bb00] 107 const __m256i t0 = _mm256_slli_epi16(in, 2); 108 // t1 = [000a|aaaa|0000|0000] 109 const __m256i t1 = _mm256_and_si256(t0, v_1f00); 110 // t2 = [0000|0000|00bb|bbbb] 111 const __m256i t2 = _mm256_and_si256(in, v_003f); 112 // t3 = [000a|aaaa|00bb|bbbb] 113 const __m256i t3 = _mm256_or_si256(t1, t2); 114 // t4 = [110a|aaaa|10bb|bbbb] 115 const __m256i t4 = _mm256_or_si256(t3, v_c080); 116 117 // 2. merge ASCII and 2-byte codewords 118 const __m256i utf8_unpacked = 119 _mm256_blendv_epi8(t4, in, one_byte_bytemask); 120 121 // 3. prepare bitmask for 8-bit lookup 122 const uint32_t M0 = one_byte_bitmask & 0x55555555; 123 const uint32_t M1 = M0 >> 7; 124 const uint32_t M2 = (M1 | M0) & 0x00ff00ff; 125 // 4. pack the bytes 126 127 const uint8_t *row = 128 &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0]; 129 const uint8_t *row_2 = 130 &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2 >> 131 16)][0]; 132 133 const __m128i shuffle = _mm_loadu_si128((__m128i *)(row + 1)); 134 const __m128i shuffle_2 = _mm_loadu_si128((__m128i *)(row_2 + 1)); 135 136 const __m256i utf8_packed = _mm256_shuffle_epi8( 137 utf8_unpacked, _mm256_setr_m128i(shuffle, shuffle_2)); 138 // 5. store bytes 139 _mm_storeu_si128((__m128i *)utf8_output, 140 _mm256_castsi256_si128(utf8_packed)); 141 utf8_output += row[0]; 142 _mm_storeu_si128((__m128i *)utf8_output, 143 _mm256_extractf128_si256(utf8_packed, 1)); 144 utf8_output += row_2[0]; 145 146 // 6. adjust pointers 147 buf += 16; 148 continue; 149 } 150 // 1. Check if there are any surrogate word in the input chunk. 151 // We have also deal with situation when there is a surrogate word 152 // at the end of a chunk. 153 const __m256i surrogates_bytemask = 154 _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_d800); 155 156 // bitmask = 0x0000 if there are no surrogates 157 // = 0xc000 if the last word is a surrogate 158 const uint32_t surrogates_bitmask = 159 static_cast<uint32_t>(_mm256_movemask_epi8(surrogates_bytemask)); 160 // It might seem like checking for surrogates_bitmask == 0xc000 could help. 161 // However, it is likely an uncommon occurrence. 162 if (surrogates_bitmask == 0x00000000) { 163 // case: code units from register produce either 1, 2 or 3 UTF-8 bytes 164 const __m256i dup_even = _mm256_setr_epi16( 165 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e, 166 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e); 167 168 /* In this branch we handle three cases: 169 1. [0000|0000|0ccc|cccc] => [0ccc|cccc] - 170 single UFT-8 byte 171 2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc] - two 172 UTF-8 bytes 173 3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - 174 three UTF-8 bytes 175 176 We expand the input word (16-bit) into two code units (32-bit), thus 177 we have room for four bytes. However, we need five distinct bit 178 layouts. Note that the last byte in cases #2 and #3 is the same. 179 180 We precompute byte 1 for case #1 and the common byte for cases #2 & #3 181 in register t2. 182 183 We precompute byte 1 for case #3 and -- **conditionally** -- precompute 184 either byte 1 for case #2 or byte 2 for case #3. Note that they 185 differ by exactly one bit. 186 187 Finally from these two code units we build proper UTF-8 sequence, taking 188 into account the case (i.e, the number of bytes to write). 189 */ 190 /** 191 * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce: 192 * t2 => [0ccc|cccc] [10cc|cccc] 193 * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb]) 194 */ 195 #define simdutf_vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x)) 196 // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc] 197 const __m256i t0 = _mm256_shuffle_epi8(in, dup_even); 198 // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc] 199 const __m256i t1 = _mm256_and_si256(t0, simdutf_vec(0b0011111101111111)); 200 // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc] 201 const __m256i t2 = _mm256_or_si256(t1, simdutf_vec(0b1000000000000000)); 202 203 // [aaaa|bbbb|bbcc|cccc] => [0000|aaaa|bbbb|bbcc] 204 const __m256i s0 = _mm256_srli_epi16(in, 4); 205 // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00] 206 const __m256i s1 = _mm256_and_si256(s0, simdutf_vec(0b0000111111111100)); 207 // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa] 208 const __m256i s2 = _mm256_maddubs_epi16(s1, simdutf_vec(0x0140)); 209 // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa] 210 const __m256i s3 = _mm256_or_si256(s2, simdutf_vec(0b1100000011100000)); 211 const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, 212 simdutf_vec(0b0100000000000000)); 213 const __m256i s4 = _mm256_xor_si256(s3, m0); 214 #undef simdutf_vec 215 216 // 4. expand code units 16-bit => 32-bit 217 const __m256i out0 = _mm256_unpacklo_epi16(t2, s4); 218 const __m256i out1 = _mm256_unpackhi_epi16(t2, s4); 219 220 // 5. compress 32-bit code units into 1, 2 or 3 bytes -- 2 x shuffle 221 const uint32_t mask = (one_byte_bitmask & 0x55555555) | 222 (one_or_two_bytes_bitmask & 0xaaaaaaaa); 223 // Due to the wider registers, the following path is less likely to be 224 // useful. 225 /*if(mask == 0) { 226 // We only have three-byte code units. Use fast path. 227 const __m256i shuffle = 228 _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 229 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1); const __m256i utf8_0 = 230 _mm256_shuffle_epi8(out0, shuffle); const __m256i utf8_1 = 231 _mm256_shuffle_epi8(out1, shuffle); 232 _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0)); 233 utf8_output += 12; 234 _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1)); 235 utf8_output += 12; 236 _mm_storeu_si128((__m128i*)utf8_output, 237 _mm256_extractf128_si256(utf8_0,1)); utf8_output += 12; 238 _mm_storeu_si128((__m128i*)utf8_output, 239 _mm256_extractf128_si256(utf8_1,1)); utf8_output += 12; buf += 16; ... [18381 characters truncated for page size]

{"command": "curl -s --max-time 20 https://raw.githubusercontent.com/simdutf/simdutf/master/src/tables/utf16_to_utf8_tables.h -o /tmp/tables.h && head -30 /tmp/tables.h && grep -c '' /tmp/tables.h"}

// file generated by scripts/sse_convert_utf16_to_utf8.py #ifndef SIMDUTF_UTF16_TO_UTF8_TABLES_H #define SIMDUTF_UTF16_TO_UTF8_TABLES_H namespace simdutf { namespace { namespace tables { namespace utf16_to_utf8 { // 1 byte for length, 16 bytes for mask const uint8_t pack_1_2_utf8_bytes[256][17] = { {16, 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14}, {15, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 0x80}, {15, 1, 0, 3, 2, 5, 4, 7, 6, 8, 11, 10, 13, 12, 15, 14, 0x80}, {14, 0, 3, 2, 5, 4, 7, 6, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80}, {15, 1, 0, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 0x80}, {14, 0, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80}, {14, 1, 0, 2, 5, 4, 7, 6, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80}, {13, 0, 2, 5, 4, 7, 6, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80, 0x80}, {15, 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 10, 13, 12, 15, 14, 0x80}, {14, 0, 3, 2, 5, 4, 7, 6, 9, 8, 10, 13, 12, 15, 14, 0x80, 0x80}, {14, 1, 0, 3, 2, 5, 4, 7, 6, 8, 10, 13, 12, 15, 14, 0x80, 0x80}, {13, 0, 3, 2, 5, 4, 7, 6, 8, 10, 13, 12, 15, 14, 0x80, 0x80, 0x80}, {14, 1, 0, 2, 5, 4, 7, 6, 9, 8, 10, 13, 12, 15, 14, 0x80, 0x80}, {13, 0, 2, 5, 4, 7, 6, 9, 8, 10, 13, 12, 15, 14, 0x80, 0x80, 0x80}, {13, 1, 0, 2, 5, 4, 7, 6, 8, 10, 13, 12, 15, 14, 0x80, 0x80, 0x80}, {12, 0, 2, 5, 4, 7, 6, 8, 10, 13, 12, 15, 14, 0x80, 0x80, 0x80, 0x80}, {15, 1, 0, 3, 2, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 0x80}, {14, 0, 3, 2, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80}, {14, 1, 0, 3, 2, 4, 7, 6, 8, 11, 10, 13, 12, 15, 14, 0x80, 0x80}, 768 --- Command finished with exit code: 0 ---

{"command": "grep -n 'pack_1_2_3_utf8_bytes\\|pack_1_2_utf8_bytes\\|^}' /tmp/tables.h | head; tail -5 /tmp/tables.h"}

11:const uint8_t pack_1_2_utf8_bytes[256][17] = { 274:const uint8_t pack_1_2_3_utf8_bytes[256][17] = { 763:} // namespace utf16_to_utf8 764:} // namespace tables 765:} // unnamed namespace 766:} // namespace simdutf } // namespace tables } // unnamed namespace } // namespace simdutf #endif // SIMDUTF_UTF16_TO_UTF8_TABLES_H --- Command finished with exit code: 0 ---

{"command": "curl -s --max-time 20 https://raw.githubusercontent.com/simdutf/simdutf/master/scripts/sse_convert_utf16_to_utf8.py -o /tmp/gen.py && sed -n 1,120p /tmp/gen.py"}

#!/usr/bin/env python3 import sys def format_array(array): result = [] for value in array: if value < 0 or value == 0x80: result.append('0x80') else: result.append(str(value)) return ', '.join(result) def assure_array_length(array, size, value = 0x80): while len(array) < size: array.append(value) CPP_1_2 = """ // 1 byte for length, 16 bytes for mask const uint8_t pack_1_2_utf8_bytes[256][17] = { %(rows)s }; """ # For all patterns the 0th element of shuffle is 0. # We may reuse that entry to store length, but it would # require some changes in C++ code. def shuffle_for_conversion_1_or_2_utf8_bytes(file): rows = [] indent = (' ' * 4) for shuffle, size in shuffle_for_conversion_1_or_2_utf8_bytes_aux(): array_str = [] for value in [size] + shuffle: if value == 0x80: array_str.append('0x80') else: array_str.append(str(value)) array = ','.join(array_str) rows.append(f'{indent}{{{array}}}') file.write(CPP_1_2 % {'rows': ',\n'.join(rows)}) def shuffle_for_conversion_1_or_2_utf8_bytes_aux(): # We process 8 x 16-bit word # a bit one indices a word having values 0x00..0x7f (produces a single UTF-8 byte) # a bit zero indices a word having values 0x0080..0x7ff (produces two UTF-8 bytes) # Our input is a 16-bit word in form hhggffeeddccbbaa -- the bits are doubled # (h - MSB, a - LSB). In a C++ code we transform it using the following formula: # # in = hhggffeeddccbbaa # t0 = in & 0x5555 // t0 = 0h0g0f0e0d0c0b0a # t1 = t0 >> 7 // t1 = 00000000h0g0f0e0 # t2 = (t0 | t1) & 0xff // t2 = hdgcfbea for mask in range(256): def getbit(k): return (mask & (1 << k) != 0) a = getbit(0) b = getbit(2) c = getbit(4) d = getbit(6) e = getbit(1) f = getbit(3) g = getbit(5) h = getbit(7) shuffle = [] for word_index, bit in enumerate([a, b, c, d, e, f, g, h]): if bit: # 1 byte shuffle.append(word_index * 2) else: # 2 bytes shuffle.append(word_index * 2 + 1) shuffle.append(word_index * 2) output_bytes = len(shuffle) while (len(shuffle) < 16): shuffle.append(0x80) yield (shuffle, output_bytes) CPP_1_2_3 = """ // 1 byte for length, 16 bytes for mask const uint8_t pack_1_2_3_utf8_bytes[256][17] = { %(rows)s }; """ def shuffle_for_conversion_1_2_3_utf8_bytes(file): rows = [] indent = (' ' * 4) for shuffle, size in shuffle_for_conversion_1_2_3_utf8_bytes_aux(): array_str = [] for value in [size] + shuffle: if value == 0x80: array_str.append('0x80') else: array_str.append(str(value)) array = ','.join(array_str) rows.append(f'{indent}{{{array}}}') file.write(CPP_1_2_3 % {'rows': ',\n'.join(rows)}) def shuffle_for_conversion_1_2_3_utf8_bytes_aux(): # There are two 8-bit bitmask telling how many bytes each word produces (1, 2 or 3). # mask1 = ddccbbaa -- output exactly one byte (d - MSB, a - LSB) # mask2 = hhggffee -- output one or two bytes # Please note that each bit is duplicated. In final form these bits are interleaved: --- Command finished with exit code: 0 ---

{"command": "sed -n 120,220p /tmp/gen.py"}

# Please note that each bit is duplicated. In final form these bits are interleaved: # mask = (mask1 & 0x5555) | (mask2 & 0xaaaa) # = hdgcfbea # Each two-bit subword decides how many bytes will be copied from a 32-bit word of register: # | e | a | ea | # +---+---+----+------- # | 0 | 0 | 0 | 3 bytes # | 0 | 1 | 1 | -- such combination will never come from C++ code, it has no sense # | 1 | 0 | 2 | 2 bytes # | 1 | 1 | 3 | 1 byte for mask in range(256): empty = 0x80 shuffle = [] for i in range(4): subword = mask & 0b11 mask >>= 2 if subword == 0: shuffle.append(i*4 + 2) shuffle.append(i*4 + 3) shuffle.append(i*4 + 1) elif subword == 3: shuffle.append(i*4 + 0) elif subword == 2: shuffle.append(i*4 + 3) shuffle.append(i*4 + 1) output_bytes = len(shuffle) while (len(shuffle) < 16): shuffle.append(empty) yield (shuffle, output_bytes) CPP_EXPAND_SURROGATES = """ // 2x16 bytes for masks, dwords_consumed const uint8_t expand_surrogates[256][33] = { %(rows)s }; """ def shuffle_for_expanding_surrogate_pairs(file): rows = [] indent = (' ' * 4) for shuffle, dwords_consumed in shuffle_for_expanding_surrogate_pairs_aux(): # If we consume, say 6 dwords of 8, then anyway the C++ conversion # routing convert 2 extra dwords (zeroed) into 2 UTF-8 bytes. Thus # we have to subtract this zero_dwords from saved bytes, to get # the real number of output bytes. zero_dwords = 8 - dwords_consumed; assert len(shuffle) == 32 rows.append('%s{%s}' % (indent, format_array(shuffle + [zero_dwords]))) file.write(CPP_EXPAND_SURROGATES % {'rows': ',\n'.join(rows)}) # Our input 8-bit bitmask informs which word contains a surrogate (low or high one). # At this point we do not need to know which is which, as we assume that word # expansion is done after validation. (Let's assume L - low surrogate, H - high # surrogate, V - any valid non-surrogate word). # # Example 1: bitmask 1001'1110 describes a sequence V-L-H-L-H-V-V-? -- the last # surrogate word might be either L or H, we'll ignore it. Two adjacent bits # are expected to contain low & high surrogates # # Example 2: bitmask 0011'0110 describes a sequence V-L-K-V-L-H-V-V. # # Example 3: bitmask 0000'0001 is not valid --- sole surrogate word must not start # a chunk of string, and C++ takes care not to pass such wrong input. # # Example 4: bitmask 0000'1110 is not valid too # # We expand all words into 32-bit lanes, spanning two SSE registers. def shuffle_for_expanding_surrogate_pairs_aux(): def shuffle_mask(mask): result = [] prev = 'V' dwords_consumed = 0 for i in range(8): bit = bool(mask & (1 << i)) if bit: if prev == 'V': curr = 'L' elif prev == 'L': curr = 'H' elif prev == 'H': curr = 'L' result.append(2*i + 0) result.append(2*i + 1) if curr == 'L': dwords_consumed += 1 else: --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\ndef gen_1_2():\n rows = []\n for mask in range(256):\n bits = [(mask >> k) & 1 for k in range(8)]\n # order a,b,c,d = bits 0,2,4,6 ; e,f,g,h = bits 1,3,5,7\n order = [bits[0], bits[2], bits[4], bits[6], bits[1], bits[3], bits[5], bits[7]]\n sh = []\n for wi, bit in enumerate(order):\n if bit:\n sh.append(wi*2)\n else:\n sh.append(wi*2+1); sh.append(wi*2)\n n = len(sh)\n while len(sh) < 16: sh.append(0x80)\n rows.append([n] + sh)\n return rows\n\ndef gen_1_2_3():\n rows = []\n for m in range(256):\n mask = m\n sh = []\n for i in range(4):\n sub = mask & 3\n mask >>= 2\n if sub == 0:\n sh += [i*4+2, i*4+3, i*4+1]\n elif sub == 3:\n sh += [i*4+0]\n elif sub == 2:\n sh += [i*4+3, i*4+1]\n # sub == 1 impossible: nothing\n n = len(sh)\n while len(sh) < 16: sh.append(0x80)\n rows.append([n] + sh)\n return rows\n\ndef emit(f, name, rows):\n f.write(f\"static const uint8_t {name}[256][17] = {{\\n\")\n for r in rows:\n f.write(\" {\" + \",\".join(str(v) for v in r) + \"},\\n\")\n f.write(\"};\\n\\n\")\n\nwith open(\"submission/tables.h\", \"w\") as f:\n f.write(\"// generated shuffle tables for utf16->utf8 packing (simdutf-style)\\n\")\n f.write(\"#ifndef TABLES_H\\n#define TABLES_H\\n#include <stdint.h>\\n\\n\")\n emit(f, \"pack_1_2_utf8_bytes\", gen_1_2())\n emit(f, \"pack_1_2_3_utf8_bytes\", gen_1_2_3())\n f.write(\"#endif\\n\")\nprint(\"done\")\nEOF\n# spot check against simdutf reference table\npython3 - <<'EOF'\nimport re\nref = open(\"/tmp/tables.h\").read()\nmine = open(\"submission/tables.h\").read()\ndef rows(text, name):\n i = text.index(name)\n j = text.index(\"};\", i)\n body = text[i:j]\n return [tuple(int(x,0) for x in r.split(\",\")) for r in re.findall(r\"\\{([^}]*)\\}\", body)]\nfor name in (\"pack_1_2_utf8_bytes\",\"pack_1_2_3_utf8_bytes\"):\n a = rows(ref, name); b = rows(mine, name)\n assert len(a)==256 and a==b, (name, next((k,a[k],b[k]) for k in range(256) if a[k]!=b[k]))\nprint(\"tables match simdutf\")\nEOF"}

done Traceback (most recent call last): File "<stdin>", line 10, in <module> File "<stdin>", line 8, in rows File "<stdin>", line 8, in <genexpr> ValueError: invalid literal for int() with base 0: '\n {16' --- Command finished with exit code: 1 --- Exit code: 1

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nimport re\ndef rows(text, name):\n i = text.index(name)\n j = text.index(\"};\", i)\n body = text[i:j]\n return [tuple(int(x.strip(),0) for x in r.split(\",\")) for r in re.findall(r\"\\{([^{}]*)\\}\", body)]\nref = open(\"/tmp/tables.h\").read()\nmine = open(\"submission/tables.h\").read()\nfor name in (\"pack_1_2_utf8_bytes\",\"pack_1_2_3_utf8_bytes\"):\n a = rows(ref, name); b = rows(mine, name)\n assert len(a)==256 and len(b)==256, (len(a),len(b))\n assert a==b, (name, next((k,a[k],b[k]) for k in range(256) if a[k]!=b[k]))\nprint(\"tables match simdutf\")\nEOF"}

tables match simdutf --- Command finished with exit code: 0 ---

{"file_path": "submission/solve.c", "content": "// solve.c \u2014 fast UTF-16LE -> UTF-8 transcoder (AVX2, simdutf-style).\n// See ../spec.md. Grade with ../grade.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include \"tables.h\"\n\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"avx2,bmi2\")))\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n const uint16_t *buf = in;\n const uint16_t *end = in + n;\n uint8_t *o = out;\n\n const __m256i v_ff80 = _mm256_set1_epi16((short)0xff80);\n const __m256i v_f800 = _mm256_set1_epi16((short)0xf800);\n const __m256i v_d800 = _mm256_set1_epi16((short)0xd800);\n const __m256i v_c080 = _mm256_set1_epi16((short)0xc080);\n const __m256i v_0000 = _mm256_setzero_si256();\n\n // Main vector loop. Margin 20 guarantees all 16-byte overhang stores stay\n // within the 3n+4 output capacity (see analysis: worst case needs i<=n-19).\n while (end - buf >= 20) {\n __m256i v = _mm256_loadu_si256((const __m256i *)buf);\n if (_mm256_testz_si256(v, v_ff80)) {\n // ASCII fast path; try 32 units at once.\n if (end - buf >= 32) {\n __m256i v1 = _mm256_loadu_si256((const __m256i *)(buf + 16));\n if (_mm256_testz_si256(v1, v_ff80)) {\n __m256i packed = _mm256_permute4x64_epi64(\n _mm256_packus_epi16(v, v1), 0xD8);\n _mm256_storeu_si256((__m256i *)o, packed);\n buf += 32; o += 32;\n continue;\n }\n }\n __m128i p = _mm_packus_epi16(_mm256_castsi256_si128(v),\n _mm256_extracti128_si256(v, 1));\n _mm_storeu_si128((__m128i *)o, p);\n buf += 16; o += 16;\n continue;\n }\n\n const __m256i one_byte_bytemask =\n _mm256_cmpeq_epi16(_mm256_and_si256(v, v_ff80), v_0000);\n const uint32_t one_byte_bitmask =\n (uint32_t)_mm256_movemask_epi8(one_byte_bytemask);\n\n const __m256i one_or_two_bytes_bytemask =\n _mm256_cmpeq_epi16(_mm256_and_si256(v, v_f800), v_0000);\n const uint32_t one_or_two_bytes_bitmask =\n (uint32_t)_mm256_movemask_epi8(one_or_two_bytes_bytemask);\n\n if (one_or_two_bytes_bitmask == 0xffffffff) {\n // All units are 1-2 UTF-8 bytes.\n const __m256i v_1f00 = _mm256_set1_epi16(0x1f00);\n const __m256i v_003f = _mm256_set1_epi16(0x003f);\n const __m256i t0 = _mm256_slli_epi16(v, 2);\n const __m256i t1 = _mm256_and_si256(t0, v_1f00);\n const __m256i t2 = _mm256_and_si256(v, v_003f);\n const __m256i t3 = _mm256_or_si256(t1, t2);\n const __m256i t4 = _mm256_or_si256(t3, v_c080);\n const __m256i utf8_unpacked =\n _mm256_blendv_epi8(t4, v, one_byte_bytemask);\n\n const uint32_t M0 = one_byte_bitmask & 0x55555555;\n const uint32_t M1 = M0 >> 7;\n const uint32_t M2 = (M1 | M0) & 0x00ff00ff;\n\n const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0];\n const uint8_t *row_2 = &pack_1_2_utf8_bytes[(uint8_t)(M2 >> 16)][0];\n const __m128i shuffle = _mm_loadu_si128((const __m128i *)(row + 1));\n const __m128i shuffle_2 = _mm_loadu_si128((const __m128i *)(row_2 + 1));\n\n const __m256i utf8_packed = _mm256_shuffle_epi8(\n utf8_unpacked, _mm256_setr_m128i(shuffle, shuffle_2));\n _mm_storeu_si128((__m128i *)o, _mm256_castsi256_si128(utf8_packed));\n o += row[0];\n _mm_storeu_si128((__m128i *)o, _mm256_extracti128_si256(utf8_packed, 1));\n o += row_2[0];\n buf += 16;\n continue;\n }\n\n const __m256i surrogates_bytemask =\n _mm256_cmpeq_epi16(_mm256 ... [5079 characters truncated for page size]

Updated submission/solve.c (199 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 — fast UTF-16LE -> UTF-8 transcoder (AVX2, simdutf-style). 2+ // See ../spec.md. Grade with ../grade. 5+ #include <string.h> 6+ #include <immintrin.h> 7+ #include "tables.h" 9- size_t utf16_to_utf8(const uint16_t *in, size_t n, uint8_t *out) { 10- size_t o = 0; 11- for (size_t i = 0; i < n; i++) { 12- uint32_t c = in[i]; 13- if (c < 0x80) { 14- out[o++] = (uint8_t)c; 15- } else if (c < 0x800) { 16- out[o++] = (uint8_t)(0xC0 | (c >> 6)); 17- out[o++] = (uint8_t)(0x80 | (c & 0x3F)); 18- } else if (c < 0xD800 || c >= 0xE000) { 19- out[o++] = (uint8_t)(0xE0 | (c >> 12)); 20- out[o++] = (uint8_t)(0x80 | ((c >> 6) & 0x3F)); ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode && ./grade", "timeout": 600000}

build 1.4s verify 2.0s PASS measure 2.7s 23,839,650 instructions (given: 77,976,206) SCORE +1.7097 (3.271x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nmkdir -p /tmp/prof\npython3 - <<'EOF'\nimport random, struct, sys\nsys.argv=[0]\nsys.path.insert(0,'verify')\nimport importlib.util\nspec = importlib.util.spec_from_file_location(\"gc\",\"verify/gen_corpus.py\")\ngc = importlib.util.module_from_spec(spec)\n# don't run main; import functions\nimport types\nsrc = open(\"verify/gen_corpus.py\").read()\nns = {}\nexec(src.replace('if __name__ == \"__main__\":\\n main()',''), ns)\ngen_record = ns['gen_record']\nfor regime in [\"ascii\",\"latin\",\"cjk\",\"emoji\"]:\n rng = random.Random(42)\n total = 250000; done=0; records=[]\n while done < total:\n units = rng.randrange(500,3000)\n rec = gen_record(rng, regime, units)\n if rec and 0xD800 <= rec[-1] <= 0xDBFF: rec.pop()\n records.append(rec); done += len(rec)\n with open(f\"/tmp/prof/{regime}.bin\",\"wb\") as f:\n for rec in records:\n f.write(struct.pack(\"<I\",len(rec)))\n f.write(struct.pack(f\"<{len(rec)}H\",*rec))\n print(regime, done)\nEOF\nfor r in ascii latin cjk emoji; do\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.$r .build/runner /tmp/prof/$r.bin >/dev/null 2>&1\n echo -n \"$r: \"; grep -E '^[0-9]+ [0-9]+' /tmp/prof/cg.$r | awk '{s+=$2} END {print s}'\ndone", "timeout": 300000}

ascii 250226 latin 252257 cjk 252402 emoji 252017 ascii: 869628 latin: 4817519 cjk: 8311461 emoji: 18408416 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --callgrind-out-file=/tmp/prof/cg.latin.ann .build/runner /tmp/prof/latin.bin >/dev/null 2>&1\ncallgrind_annotate --auto=yes /tmp/prof/cg.latin.ann 2>/dev/null | head -60"}

-------------------------------------------------------------------------------- Profile data file '/tmp/prof/cg.latin.ann' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 111727 Trigger: Program termination Profiled target: .build/runner /tmp/prof/latin.bin (PID 439, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 835,473 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 354,241 (42.40%) submission/solve.c:utf16_to_utf8 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner] 317,665 (38.02%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:utf16_to_utf8 117,083 (14.01%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8 46,055 ( 5.51%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:utf16_to_utf8 -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h -------------------------------------------------------------------------------- Ir -- line 92 ---------------------------------------- . { . return (__m256i)__builtin_ia32_packusdw256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_packus_epi16 (__m256i __A, __m256i __B) . { 180 ( 0.02%) return (__m256i)__builtin_ia32_packuswb256 ((__v16hi)__A, (__v16hi)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_add_epi8 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v32qu)__A + (__v32qu)__B); . } -- line 108 ---------------------------------------- -- line 173 ---------------------------------------- . (__v4di)(__m256i)(B), \ . (int)(N) * 8)) . #endif . . extern __inline __m256i --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ncallgrind_annotate --auto=yes /tmp/prof/cg.emoji 2>/dev/null | grep -A200 'Auto-annotated source: submission/solve.c' | head -120"}

-- Auto-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 4 ---------------------------------------- . #include <stddef.h> . #include <string.h> . #include <immintrin.h> . #include "tables.h" . . #define INVALID ((size_t)-1) . . __attribute__((target("avx2,bmi2"))) 564 ( 0.02%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) { . const uint16_t *buf = in; 141 ( 0.00%) const uint16_t *end = in + n; 141 ( 0.00%) uint8_t *o = out; . . const __m256i v_ff80 = _mm256_set1_epi16((short)0xff80); . const __m256i v_f800 = _mm256_set1_epi16((short)0xf800); . const __m256i v_d800 = _mm256_set1_epi16((short)0xd800); . const __m256i v_c080 = _mm256_set1_epi16((short)0xc080); . const __m256i v_0000 = _mm256_setzero_si256(); . . // Main vector loop. Margin 20 guarantees all 16-byte overhang stores stay . // within the 3n+4 output capacity (see analysis: worst case needs i<=n-19). 65,791 ( 1.83%) while (end - buf >= 20) { . __m256i v = _mm256_loadu_si256((const __m256i *)buf); 32,402 ( 0.90%) if (_mm256_testz_si256(v, v_ff80)) { . // ASCII fast path; try 32 units at once. 612 ( 0.02%) if (end - buf >= 32) { . __m256i v1 = _mm256_loadu_si256((const __m256i *)(buf + 16)); 602 ( 0.02%) if (_mm256_testz_si256(v1, v_ff80)) { . __m256i packed = _mm256_permute4x64_epi64( . _mm256_packus_epi16(v, v1), 0xD8); . _mm256_storeu_si256((__m256i *)o, packed); 14 ( 0.00%) buf += 32; o += 32; . continue; . } . } . __m128i p = _mm_packus_epi16(_mm256_castsi256_si128(v), . _mm256_extracti128_si256(v, 1)); . _mm_storeu_si128((__m128i *)o, p); 598 ( 0.02%) buf += 16; o += 16; 299 ( 0.01%) continue; . } . . const __m256i one_byte_bytemask = . _mm256_cmpeq_epi16(_mm256_and_si256(v, v_ff80), v_0000); . const uint32_t one_byte_bitmask = . (uint32_t)_mm256_movemask_epi8(one_byte_bytemask); . . const __m256i one_or_two_bytes_bytemask = . _mm256_cmpeq_epi16(_mm256_and_si256(v, v_f800), v_0000); . const uint32_t one_or_two_bytes_bitmask = . (uint32_t)_mm256_movemask_epi8(one_or_two_bytes_bytemask); . 31,790 ( 0.89%) if (one_or_two_bytes_bitmask == 0xffffffff) { . // All units are 1-2 UTF-8 bytes. . const __m256i v_1f00 = _mm256_set1_epi16(0x1f00); . const __m256i v_003f = _mm256_set1_epi16(0x003f); . const __m256i t0 = _mm256_slli_epi16(v, 2); . const __m256i t1 = _mm256_and_si256(t0, v_1f00); . const __m256i t2 = _mm256_and_si256(v, v_003f); . const __m256i t3 = _mm256_or_si256(t1, t2); . const __m256i t4 = _mm256_or_si256(t3, v_c080); -- line 64 ---------------------------------------- -- line 84 ---------------------------------------- . continue; . } . . const __m256i surrogates_bytemask = . _mm256_cmpeq_epi16(_mm256_and_si256(v, v_f800), v_d800); . const uint32_t surrogates_bitmask = . (uint32_t)_mm256_movemask_epi8(surrogates_bytemask); . 31,790 ( 0.89%) if (surrogates_bitmask == 0) { . // 1-3 UTF-8 bytes per unit, no surrogates. . const __m256i dup_even = _mm256_setr_epi16( . 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e, . 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e); . #define VEC16(x) _mm256_set1_epi16((short)(x)) . const __m256i t0 = _mm256_shuffle_epi8(v, dup_even); . const __m256i t1 = _mm256_and_si256(t0, VEC16(0x3f7f)); . const __m256i t2 = _mm256_or_si256(t1, VEC16(0x8000)); -- line 100 ---------------------------------------- -- line 138 ---------------------------------------- . _mm_storeu_si128((__m128i *)o, u3); . o += row3[0]; . buf += 16; . continue; . } . . // Surrogates present: scalar over up to 15 units (pair may take 16th). . { 31,790 ( 0.89%) size_t k = 0; 477,225 (13.30%) for (; k < 15; k++) { 404,497 (11.27%) uint32_t w = buf[k]; 318,150 ( 8.87%) if ((w & 0xFF80) == 0) { 145,456 ( 4.05%) *o++ = (uint8_t)w; 172,694 ( 4.81%) } else if ((w & 0xF800) == 0) { . *o++ = (uint8_t)((w >> 6) | 0xC0); . *o++ = (uint8_t)((w & 0x3F) | 0x80); 345,388 ( 9.63%) } else if ((w & 0xF800) != 0xD800) { . *o++ = (uint8_t)((w >> 12) | 0xE0); . *o++ = (uint8_t)(((w >> 6) & 0x3F) | 0x80); . *o++ = (uint8_t)((w & 0x3F) | 0x80); . } else { 86,347 ( 2.41%) uint32_t hi = w - 0xD800; 259,041 ( 7.22%) uint32_t lo = (uint32_t)buf[k + 1] - 0xDC00; . k++; 259,041 ( 7.22%) if ((hi | lo) > 0x3FF) return INVALID; 172,694 ( 4.81%) uint32_t cp = (hi << 10) + lo + 0x10000; 86,347 ( 2.41%) uint32_t be = _pdep_u32(cp, 0x073F3F3Fu) | 0xF0808080u; 86,347 ( 2.41%) uint32_t le = __builtin_bswap32(be); 86,347 ( 2.41%) memcpy(o, &le, 4); 172,694 ( 4.81%) o += 4; . } . } 31,790 ( 0.89%) buf += k; --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ncallgrind_annotate --auto=yes --threshold=95 /tmp/prof/cg.cjk 2>/dev/null | grep -B2 -A40 'submission/solve.c:utf16' | head -20\necho ======\ncallgrind_annotate --auto=yes /tmp/prof/cg.cjk 2>/dev/null | awk '/Auto-annotated source: submission\\/solve.c/,0' | grep -E '^\\s*[0-9,]+ \\(' | sort -t'(' -k2 -rn | head -30"}

-------------------------------------------------------------------------------- 595,781 (41.17%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:utf16_to_utf8 458,580 (31.69%) submission/solve.c:utf16_to_utf8 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner] 313,550 (21.67%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8 62,620 ( 4.33%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/tmmintrin.h:utf16_to_utf8 -------------------------------------------------------------------------------- -- 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) . { ====== 1,446,784 (99.97%) events annotated 63,668 ( 4.40%) while (end - buf >= 20) { 46,965 ( 3.25%) const uint8_t *row2 = &pack_1_2_3_utf8_bytes[(uint8_t)(mask >> 16)][0]; 31,316 ( 2.16%) if (_mm256_testz_si256(v, v_ff80)) { 31,310 ( 2.16%) if (surrogates_bitmask == 0) { 31,310 ( 2.16%) if (one_or_two_bytes_bitmask == 0xffffffff) { 31,310 ( 2.16%) o += row3[0]; 31,310 ( 2.16%) o += row2[0]; 31,310 ( 2.16%) o += row1[0]; 31,310 ( 2.16%) o += row0[0]; 31,310 ( 2.16%) buf += 16; 15,655 ( 1.08%) const uint8_t *row3 = &pack_1_2_3_utf8_bytes[(uint8_t)(mask >> 24)][0]; 15,655 ( 1.08%) const uint8_t *row1 = &pack_1_2_3_utf8_bytes[(uint8_t)(mask >> 8)][0]; 15,655 ( 1.08%) const uint8_t *row0 = &pack_1_2_3_utf8_bytes[(uint8_t)mask][0]; 8,855 ( 0.61%) *o++ = (uint8_t)((w & 0x3F) | 0x80); 7,496 ( 0.52%) uint32_t w = *buf++; 7,084 ( 0.49%) } else if ((w & 0xF800) != 0xD800) { 7,084 ( 0.49%) *o++ = (uint8_t)((w >> 12) | 0xE0); 7,084 ( 0.49%) *o++ = (uint8_t)(((w >> 6) & 0x3F) | 0x80); 4,044 ( 0.28%) while (buf < end) { 3,748 ( 0.26%) if (w < 0x80) { 3,542 ( 0.24%) } else if (w < 0x800) { 592 ( 0.04%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) { 296 ( 0.02%) } 206 ( 0.01%) *o++ = (uint8_t)w; 148 ( 0.01%) uint8_t *o = out; 148 ( 0.01%) return (size_t)(o - out); 148 ( 0.01%) const uint16_t *end = in + n; 6 ( 0.00%) if (end - buf >= 32) { 6 ( 0.00%) buf += 16; o += 16; --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | wc -l\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | head -100"}

319 0000000000001420 <utf16_to_utf8>: 1420: push %rbp 1421: mov %rdx,%r11 1424: lea (%rsi,%rsi,1),%rdx 1428: lea (%rdi,%rsi,2),%r8 142c: mov %rsp,%rbp 142f: sub $0x18,%rsp 1433: cmp $0x26,%rdx 1437: jle 1924 <utf16_to_utf8+0x504> 143d: mov $0xd800d800,%ecx 1442: vpcmpeqd %ymm3,%ymm3,%ymm3 1446: mov %rbx,-0x18(%rbp) 144a: mov %r11,%rax 144d: vmovd %ecx,%xmm4 1451: mov %r12,-0x10(%rbp) 1455: vmovdqa 0x2dc3(%rip),%ymm6 # 4220 <pack_1_2_utf8_bytes+0x1100> 145d: vpsllw $0x7,%ymm3,%ymm2 1462: mov %r13,-0x8(%rbp) 1466: vpbroadcastd %xmm4,%ymm4 146b: vmovdqa 0x2dcd(%rip),%ymm5 # 4240 <pack_1_2_utf8_bytes+0x1120> 1473: mov $0x73f3f3f,%ebx 1478: lea 0xba1(%rip),%r9 # 2020 <pack_1_2_3_utf8_bytes> 147f: lea 0x1c9a(%rip),%r10 # 3120 <pack_1_2_utf8_bytes> 1486: jmp 14d1 <utf16_to_utf8+0xb1> 1488: nopl 0x0(%rax,%rax,1) 1490: cmp $0x3e,%rdx 1494: jle 16b0 <utf16_to_utf8+0x290> 149a: vmovdqu 0x20(%rdi),%ymm1 149f: vptest %ymm2,%ymm1 14a4: jne 16b0 <utf16_to_utf8+0x290> 14aa: vpackuswb %ymm1,%ymm0,%ymm1 14ae: add $0x40,%rdi 14b2: add $0x20,%rax 14b6: vpermq $0xd8,%ymm1,%ymm1 14bc: vmovdqu %ymm1,-0x20(%rax) 14c1: mov %r8,%rdx 14c4: sub %rdi,%rdx 14c7: cmp $0x26,%rdx 14cb: jle 163e <utf16_to_utf8+0x21e> 14d1: vmovdqu (%rdi),%ymm0 14d5: vptest %ymm2,%ymm0 14da: je 1490 <utf16_to_utf8+0x70> 14dc: vpsllw $0xb,%ymm3,%ymm1 14e1: vpxor %xmm7,%xmm7,%xmm7 14e5: vpand %ymm2,%ymm0,%ymm8 14e9: vpand %ymm1,%ymm0,%ymm1 14ed: vpcmpeqw %ymm7,%ymm8,%ymm8 14f1: vpcmpeqw %ymm7,%ymm1,%ymm7 14f5: vpmovmskb %ymm8,%ecx 14fa: vpmovmskb %ymm7,%edx 14fe: cmp $0xffffffff,%edx 1501: je 17d0 <utf16_to_utf8+0x3b0> 1507: vpcmpeqw %ymm4,%ymm1,%ymm1 150b: vpmovmskb %ymm1,%esi 150f: test %esi,%esi 1511: jne 16d0 <utf16_to_utf8+0x2b0> 1517: and $0x55555555,%ecx 151d: and $0xaaaaaaaa,%edx 1523: mov $0xffc0ffc,%esi 1528: add $0x20,%rdi 152c: or %ecx,%edx 152e: vmovd %esi,%xmm8 1532: vpshufb %ymm6,%ymm0,%ymm1 1537: mov $0x40004000,%esi 153c: movzbl %dl,%ecx 153f: vpsrlw $0x4,%ymm0,%ymm0 1544: vpbroadcastd %xmm8,%ymm8 1549: mov %rcx,%r13 154c: vpand %ymm8,%ymm0,%ymm0 1551: vmovd %esi,%xmm8 1555: mov $0xc0e0c0e0,%esi 155a: shl $0x4,%r13 155e: vpbroadcastd %xmm8,%ymm8 1563: vpmaddubsw %ymm5,%ymm0,%ymm0 1568: add %rcx,%r13 156b: movzbl %dh,%ecx 156e: vpandn %ymm8,%ymm7,%ymm7 1573: mov %rcx,%r12 1576: vmovd %esi,%xmm8 157a: mov $0x3f7f3f7f,%esi 157f: add %r9,%r13 1582: shl $0x4,%r12 1586: vpbroadcastd %xmm8,%ymm8 158b: add %rcx,%r12 158e: mov %edx,%ecx 1590: vpor %ymm8,%ymm0,%ymm0 1595: shr $0x18,%edx 1598: shr $0x10,%ecx 159b: vpxor %ymm7,%ymm0,%ymm0 159f: vmovd %esi,%xmm7 15a3: add %r9,%r12 15a6: movzbl %cl,%ecx 15a9: vpbroadcastd %xmm7,%ymm7 15ae: mov %rcx,%rsi 15b1: vpand %ymm7,%ymm1,%ymm1 15b5: shl $0x4,%rsi 15b9: vpsllw $0xf,%ymm3,%ymm7 15be: add %rcx,%rsi 15c1: mov %rdx,%rcx 15c4: vpor %ymm7,%ymm1,%ymm1 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nhead -40 /tmp/prof/cg.latin; echo ====; grep -c 'fn=' /tmp/prof/cg.latin; echo; head -30 /tmp/prof/cg.latin.ann"}

# callgrind format version: 1 creator: callgrind-3.25.1 pid: 406 cmd: .build/runner /tmp/prof/latin.bin part: 1 desc: I1 cache: desc: D1 cache: desc: LL cache: desc: Timerange: Basic block 0 - 111728 desc: Trigger: Program termination positions: line events: Ir summary: 835473 ob=(6) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner fl=(241) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c fn=(912) utf16_to_utf8 12 286 +13 143 -11 143 -2 286 +13 286 fi=(242) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h 240 143 fi=(243) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h 1124 286 fe=(241) 15 143 fi=(242) 240 286 590 143 fi=(243) 1124 286 fi=(242) ==== 11 # callgrind format version: 1 creator: callgrind-3.25.1 pid: 439 cmd: .build/runner /tmp/prof/latin.bin part: 1 desc: I1 cache: desc: D1 cache: desc: LL cache: desc: Timerange: Basic block 0 - 111727 desc: Trigger: Program termination positions: line events: Ir summary: 835473 ob=(1) /usr/lib/ld-linux-x86-64.so.2 fl=(1) ??? fn=(0) 0x000000000001f100 cob=(6) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner cfi=(202) ??? cfn=(694) (below main) calls=1 0 0 835473 ob=(6) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | sed -n '100,220p'"}

15c4: vpor %ymm7,%ymm1,%ymm1 15c8: shl $0x4,%rcx 15cc: vpunpcklwd %ymm0,%ymm1,%ymm7 15d0: vpunpckhwd %ymm0,%ymm1,%ymm0 15d4: add %r9,%rsi 15d7: add %rdx,%rcx 15da: movzbl 0x0(%r13),%edx 15df: vpshufb 0x1(%r13),%xmm7,%xmm8 15e5: vpshufb 0x1(%r12),%xmm0,%xmm1 15ec: vmovdqu %xmm8,(%rax) 15f0: vextracti128 $0x1,%ymm7,%xmm7 15f6: add %r9,%rcx 15f9: vextracti128 $0x1,%ymm0,%xmm0 15ff: add %rax,%rdx 1602: movzbl (%r12),%eax 1607: vpshufb 0x1(%rsi),%xmm7,%xmm7 160d: vpshufb 0x1(%rcx),%xmm0,%xmm0 1613: vmovdqu %xmm1,(%rdx) 1617: add %rax,%rdx 161a: movzbl (%rsi),%eax 161d: vmovdqu %xmm7,(%rdx) 1621: add %rax,%rdx 1624: movzbl (%rcx),%eax 1627: vmovdqu %xmm0,(%rdx) 162b: add %rdx,%rax 162e: mov %r8,%rdx 1631: sub %rdi,%rdx 1634: cmp $0x26,%rdx 1638: jg 14d1 <utf16_to_utf8+0xb1> 163e: vzeroupper 1641: mov -0x18(%rbp),%rbx 1645: mov -0x10(%rbp),%r12 1649: mov -0x8(%rbp),%r13 164d: cmp %r8,%rdi 1650: jae 16a7 <utf16_to_utf8+0x287> 1652: mov $0x73f3f3f,%r9d 1658: jmp 166e <utf16_to_utf8+0x24e> 165a: nopw 0x0(%rax,%rax,1) 1660: mov %cl,(%rax) 1662: mov %rsi,%rdi 1665: add $0x1,%rax 1669: cmp %r8,%rdi 166c: jae 16a7 <utf16_to_utf8+0x287> 166e: movzwl (%rdi),%ecx 1671: lea 0x2(%rdi),%rsi 1675: mov %ecx,%edx 1677: cmp $0x7f,%cx 167b: jbe 1660 <utf16_to_utf8+0x240> 167d: cmp $0x7ff,%ecx 1683: ja 1878 <utf16_to_utf8+0x458> 1689: shr $0x6,%ecx 168c: and $0x3f,%edx 168f: mov %rsi,%rdi 1692: add $0x2,%rax 1696: or $0xffffffc0,%ecx 1699: or $0xffffff80,%edx 169c: mov %cl,-0x2(%rax) 169f: mov %dl,-0x1(%rax) 16a2: cmp %r8,%rdi 16a5: jb 166e <utf16_to_utf8+0x24e> 16a7: leave 16a8: sub %r11,%rax 16ab: ret 16ac: nopl 0x0(%rax) 16b0: vextracti128 $0x1,%ymm0,%xmm1 16b6: add $0x20,%rdi 16ba: add $0x10,%rax 16be: vpackuswb %xmm1,%xmm0,%xmm0 16c2: vmovdqu %xmm0,-0x10(%rax) 16c7: jmp 14c1 <utf16_to_utf8+0xa1> 16cc: nopl 0x0(%rax) 16d0: xor %ecx,%ecx 16d2: jmp 16f0 <utf16_to_utf8+0x2d0> 16d4: nop 16d5: data16 cs nopw 0x0(%rax,%rax,1) 16e0: mov %dl,(%rax) 16e2: add $0x1,%rax 16e6: add $0x1,%rcx 16ea: cmp $0xe,%rcx 16ee: ja 1729 <utf16_to_utf8+0x309> 16f0: movzwl (%rdi,%rcx,2),%edx 16f4: lea (%rcx,%rcx,1),%r12 16f8: cmp $0x7f,%dx 16fc: jbe 16e0 <utf16_to_utf8+0x2c0> 16fe: movzwl %dx,%esi 1701: cmp $0x7ff,%dx 1706: ja 1738 <utf16_to_utf8+0x318> 1708: shr $0x6,%esi 170b: and $0x3f,%edx 170e: add $0x1,%rcx 1712: add $0x2,%rax 1716: or $0xffffffc0,%esi 1719: or $0xffffff80,%edx 171c: mov %sil,-0x2(%rax) 1720: mov %dl,-0x1(%rax) 1723: cmp $0xe,%rcx 1727: jbe 16f0 <utf16_to_utf8+0x2d0> 1729: lea (%rdi,%rcx,2),%rdi 172d: jmp 14c1 <utf16_to_utf8+0xa1> 1732: nopw 0x0(%rax,%rax,1) 1738: mov %edx,%r13d 173b: and $0xf800,%r13w 1741: cmp $0xd800,%r13w 1747: je 1780 <utf16_to_utf8+0x360> 1749: mov %esi,%r12d 174c: shr $0x6,%esi 174f: and $0x3f,%edx 1752: add $0x3,%rax 1756: shr $0xc,%r12d 175a: and $0x3f,%esi 175d: or $0xffffff80,%edx 1760: or $0xffffffe0,%r12d 1764: or $0xffffff80,%esi 1767: mov %dl,-0x1(%rax) 176a: mov %r12b,-0x3(%rax) 176e: mov %sil,-0x2(%rax) 1772: jmp 16e6 <utf16_to_utf8+0x2c6> 1777: nopw 0x0(%rax,%rax,1) 1780: movzwl 0x2(%rdi,%r12,1),%r12d 1786: sub $0xd800,%esi 178c: lea -0xdc00(%r12),%edx --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ngrep -H '^summary' /tmp/prof/cg.* ; echo ----; head -25 /tmp/prof/cg.cjk"}

/tmp/prof/cg.ascii:summary: 151198 /tmp/prof/cg.cjk:summary: 1447228 /tmp/prof/cg.emoji:summary: 3587948 /tmp/prof/cg.latin:summary: 835473 /tmp/prof/cg.latin.ann:summary: 835473 ---- # callgrind format version: 1 creator: callgrind-3.25.1 pid: 413 cmd: .build/runner /tmp/prof/cjk.bin part: 1 desc: I1 cache: desc: D1 cache: desc: LL cache: desc: Timerange: Basic block 0 - 137392 desc: Trigger: Program termination positions: line events: Ir summary: 1447228 ob=(6) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner fl=(241) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c fn=(912) utf16_to_utf8 12 296 +13 148 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ngrep '^summary' .build/callgrind.runner.out .build/callgrind.runner_given.out\npython3 - <<'EOF'\nimport re\nfor f in [\".build/callgrind.runner.out\", \".build/callgrind.runner_given.out\"]:\n total = 0\n for line in open(f):\n ls = line.strip()\n if re.match(r\"^\\d+ \\d+$\", ls) or re.match(r\"^\\d+ \\d+ \", ls):\n total += int(ls.split()[1])\n print(f, total)\nEOF"}

.build/callgrind.runner.out:summary: 4376496 .build/callgrind.runner_given.out:summary: 15594898 .build/callgrind.runner.out 23839650 .build/callgrind.runner_given.out 77976206 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\ndef gen_1_2():\n rows = []\n for mask in range(256):\n bits = [(mask >> k) & 1 for k in range(8)]\n order = [bits[0], bits[2], bits[4], bits[6], bits[1], bits[3], bits[5], bits[7]]\n sh = []\n for wi, bit in enumerate(order):\n if bit: sh.append(wi*2)\n else: sh.append(wi*2+1); sh.append(wi*2)\n n = len(sh)\n while len(sh) < 16: sh.append(0x80)\n return_row = sh + [n] + [0]*15\n rows.append(return_row)\n return rows\n\ndef gen_1_2_3():\n rows = []\n for m in range(256):\n mask = m\n sh = []\n for i in range(4):\n sub = mask & 3\n mask >>= 2\n if sub == 0: sh += [i*4+2, i*4+3, i*4+1]\n elif sub == 3: sh += [i*4+0]\n elif sub == 2: sh += [i*4+3, i*4+1]\n # sub == 1: skip lane, emit nothing\n n = len(sh)\n while len(sh) < 16: sh.append(0x80)\n rows.append(sh + [n] + [0]*15)\n return rows\n\ndef emit(f, name, rows):\n f.write(f\"static const uint8_t {name}[256][32] __attribute__((aligned(32))) = {{\\n\")\n for r in rows:\n f.write(\" {\" + \",\".join(str(v) for v in r) + \"},\\n\")\n f.write(\"};\\n\\n\")\n\nwith open(\"submission/tables.h\", \"w\") as f:\n f.write(\"// generated shuffle tables for utf16->utf8 packing.\\n\")\n f.write(\"// row layout: bytes 0..15 = pshufb pattern, byte 16 = output length.\\n\")\n f.write(\"#ifndef TABLES_H\\n#define TABLES_H\\n#include <stdint.h>\\n\\n\")\n emit(f, \"pack_1_2_utf8_bytes\", gen_1_2())\n emit(f, \"pack_1_2_3_utf8_bytes\", gen_1_2_3())\n f.write(\"#endif\\n\")\nprint(\"ok\")\nEOF"}

ok --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nsed -n 1,60p .build/callgrind.runner.out"}

# callgrind format version: 1 creator: callgrind-3.25.1 pid: 373 cmd: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/corpus_31587.bin part: 1 desc: I1 cache: desc: D1 cache: desc: LL cache: desc: Timerange: Basic block 0 - 716890 desc: Trigger: Program termination positions: line events: Ir summary: 4376496 ob=(1) /usr/lib/ld-linux-x86-64.so.2 fl=(1) ??? fn=(0) 0x000000000001f100 cob=(6) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner cfi=(202) ??? cfn=(694) (below main) calls=1 0 0 4376496 ob=(6) fl=(241) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c fn=(912) utf16_to_utf8 12 1144 +13 572 -11 572 -2 1144 +13 1144 fi=(242) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h 240 572 fi=(243) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h 1124 1144 fe=(241) 15 572 fi=(242) 240 1144 590 572 fi=(243) 1124 1144 fi=(242) 240 572 +95 572 fi=(244) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/bmi2intrin.h 48 572 fi=(245) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h 707 1716 fe=(241) 29 27604 fi=(243) 873 13705 fe=(241) --- Command finished with exit code: 0 ---

{"content": "// solve.c \u2014 fast UTF-16LE -> UTF-8 transcoder (AVX2, simdutf-style core with\n// an added SIMD surrogate-pair path). See ../spec.md. Grade with ../grade.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n#include <immintrin.h>\n#include \"tables.h\"\n\n#define INVALID ((size_t)-1)\n\n__attribute__((target(\"avx2,bmi2\")))\nsize_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) {\n const uint16_t *buf = in;\n const uint16_t *end = in + n;\n uint8_t *o = out;\n\n const __m256i v_ff80 = _mm256_set1_epi16((short)0xff80);\n const __m256i v_f800 = _mm256_set1_epi16((short)0xf800);\n const __m256i v_d800 = _mm256_set1_epi16((short)0xd800);\n const __m256i v_0000 = _mm256_setzero_si256();\n\n while (end - buf >= 20) {\n __m256i v = _mm256_loadu_si256((const __m256i *)buf);\n if (_mm256_testz_si256(v, v_ff80)) {\n // ASCII fast path; try 32 units at once.\n if (end - buf >= 32) {\n __m256i v1 = _mm256_loadu_si256((const __m256i *)(buf + 16));\n if (_mm256_testz_si256(v1, v_ff80)) {\n __m256i packed = _mm256_permute4x64_epi64(\n _mm256_packus_epi16(v, v1), 0xD8);\n _mm256_storeu_si256((__m256i *)o, packed);\n buf += 32; o += 32;\n continue;\n }\n }\n __m128i p = _mm_packus_epi16(_mm256_castsi256_si128(v),\n _mm256_extracti128_si256(v, 1));\n _mm_storeu_si128((__m128i *)o, p);\n buf += 16; o += 16;\n continue;\n }\n\n const __m256i one_byte_bytemask =\n _mm256_cmpeq_epi16(_mm256_and_si256(v, v_ff80), v_0000);\n const uint32_t one_byte_bitmask =\n (uint32_t)_mm256_movemask_epi8(one_byte_bytemask);\n\n const __m256i one_or_two_bytes_bytemask =\n _mm256_cmpeq_epi16(_mm256_and_si256(v, v_f800), v_0000);\n const uint32_t one_or_two_bytes_bitmask =\n (uint32_t)_mm256_movemask_epi8(one_or_two_bytes_bytemask);\n\n if (one_or_two_bytes_bitmask == 0xffffffff) {\n // All units are 1-2 UTF-8 bytes.\n const __m256i v_1f00 = _mm256_set1_epi16(0x1f00);\n const __m256i v_003f = _mm256_set1_epi16(0x003f);\n const __m256i v_c080 = _mm256_set1_epi16((short)0xc080);\n const __m256i t0 = _mm256_slli_epi16(v, 2);\n const __m256i t1 = _mm256_and_si256(t0, v_1f00);\n const __m256i t2 = _mm256_and_si256(v, v_003f);\n const __m256i t3 = _mm256_or_si256(t1, t2);\n const __m256i t4 = _mm256_or_si256(t3, v_c080);\n const __m256i utf8_unpacked =\n _mm256_blendv_epi8(t4, v, one_byte_bytemask);\n\n const uint32_t M0 = one_byte_bitmask & 0x55555555;\n const uint32_t M1 = M0 >> 7;\n const uint32_t M2 = (M1 | M0) & 0x00ff00ff;\n\n const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0];\n const uint8_t *row_2 = &pack_1_2_utf8_bytes[(uint8_t)(M2 >> 16)][0];\n const __m128i shuffle = _mm_load_si128((const __m128i *)row);\n const __m128i shuffle_2 = _mm_load_si128((const __m128i *)row_2);\n\n const __m256i utf8_packed = _mm256_shuffle_epi8(\n v_0000 /*placeholder*/, v_0000);\n (void)utf8_packed;\n const __m256i packed = _mm256_shuffle_epi8(\n utf8_unpacked, _mm256_setr_m128i(shuffle, shuffle_2));\n _mm_storeu_si128((__m128i *)o, _mm256_castsi256_si128(packed));\n o += row[16];\n _mm_storeu_si128((__m128i *)o, _mm256_extracti128_si256(packed, 1));\n o += row_2[16];\n buf += 16;\n continue;\n }\n\n const __m256i surrogates_bytemask =\n _mm256_cmpeq_epi16(_mm256_and_si256(v, v_f800), v_d80 ... [9527 characters truncated for page size]

Updated submission/solve.c (279 lines): 1- // solve.c — fast UTF-16LE -> UTF-8 transcoder (AVX2, simdutf-style). 2- // See ../spec.md. Grade with ../grade. 1+ // solve.c — fast UTF-16LE -> UTF-8 transcoder (AVX2, simdutf-style core with 2+ // an added SIMD surrogate-pair path). See ../spec.md. Grade with ../grade. 20- const __m256i v_c080 = _mm256_set1_epi16((short)0xc080); 23- // Main vector loop. Margin 20 guarantees all 16-byte overhang stores stay 24- // within the 3n+4 output capacity (see analysis: worst case needs i<=n-19). 57+ const __m256i v_c080 = _mm256_set1_epi16((short)0xc080); 74- const __m128i shuffle = _mm_loadu_si128((const __m128i *)(row + 1)); 75- const __m128i shuffle_2 = _mm_loadu_si128((const __m128i *)(row_2 + 1)); 72+ const __m128i shuffle = _mm_load_si128((const __m128i *)row); 73+ const __m128i shuffle_2 = _mm_load_si128((const __m128i *)row_2); 76+ v_0000 /*placeholder*/, v_0000); 77+ (void)utf8_packed; 78+ const __m256i packed = _mm256_shuffle_epi8( 79- _mm_storeu_si128((__m128i *)o, _mm256_castsi256_si128(utf8_packed)); 80- o += row[0]; 81- _mm_storeu_si128((__m128i *)o, _mm256_extracti128_si256(utf8_packed, 1)); 82- o += row_2[0]; 80+ _mm_storeu_si128((__m128i *)o, _mm256_castsi256_si128(packed)); ...

{"file_path": "submission/solve.c", "old_string": " const __m256i utf8_packed = _mm256_shuffle_epi8(\n v_0000 /*placeholder*/, v_0000);\n (void)utf8_packed;\n const __m256i packed = _mm256_shuffle_epi8(", "new_string": " const __m256i packed = _mm256_shuffle_epi8("}

Edited submission/solve.c: replaced 1 occurrence(s) 75- const __m256i utf8_packed = _mm256_shuffle_epi8( 76- v_0000 /*placeholder*/, v_0000); 77- (void)utf8_packed; Context after edit (lines 72-78): 72│ const __m128i shuffle = _mm_load_si128((const __m128i *)row); 73│ const __m128i shuffle_2 = _mm_load_si128((const __m128i *)row_2); 74│ 75│ const __m256i packed = _mm256_shuffle_epi8( 76│ utf8_unpacked, _mm256_setr_m128i(shuffle, shuffle_2)); 77│ _mm_storeu_si128((__m128i *)o, _mm256_castsi256_si128(packed)); 78│ o += row[16];

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode && ./grade", "timeout": 600000}

build 1.4s verify 2.0s PASS measure 1.2s 16,218,409 instructions (given: 77,916,740) SCORE +2.2643 (4.804x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nfor r in ascii latin cjk emoji; do\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.$r .build/runner /tmp/prof/$r.bin >/dev/null 2>&1\n echo -n \"$r: \"; grep -E '^[0-9]+ [0-9]+' /tmp/prof/cg.$r | awk '{s+=$2} END {print s, s/250000 \" instr/unit\"}'\ndone", "timeout": 300000}

ascii: 916209 3.66484 instr/unit latin: 4268306 17.0732 instr/unit cjk: 6094944 24.3798 instr/unit emoji: 9378676 37.5147 instr/unit --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --callgrind-out-file=/tmp/prof/cg.latin.ann .build/runner /tmp/prof/latin.bin >/dev/null 2>&1\ncallgrind_annotate --auto=yes --threshold=99.9 /tmp/prof/cg.latin.ann 2>/dev/null | awk '/Auto-annotated source: submission\\/solve.c/,0' | grep -E '\\([0-9. ]+%\\)' | sort -t'(' -k2 -rn | head -25"}

749,650 (99.96%) events annotated 129,060 (17.21%) return (__m256i) ((__v4du)__A & (__v4du)__B); 71,700 ( 9.56%) return (__m256i) ((__v4du)__A | (__v4du)__B); 62,949 ( 8.39%) while (end - buf >= 20) { 43,020 ( 5.74%) const uint8_t *row_2 = &pack_1_2_utf8_bytes[(uint8_t)(M2 >> 16)][0]; 30,974 ( 4.13%) if (_mm256_testz_si256(v, v_ff80)) { 29,395 ( 3.92%) return (__m256i) ((__v16hi)__A == (__v16hi)__B); 28,966 ( 3.86%) const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0]; 28,680 ( 3.82%) if (one_or_two_bytes_bitmask == 0xffffffff) { 28,680 ( 3.82%) o += row_2[16]; 28,680 ( 3.82%) o += row[16]; 28,680 ( 3.82%) const uint32_t M1 = M0 >> 7; 28,680 ( 3.82%) return __builtin_ia32_pmovmskb256 ((__v32qi)__A); 16,623 ( 2.22%) return *__P; 14,626 ( 1.95%) return (__m256i) __builtin_ia32_pshufb256 ((__v32qi)__X, 14,340 ( 1.91%) return (__m256i) __builtin_ia32_vinsertf128_si256 ((__v8si)__X, 14,340 ( 1.91%) return (__m256i) __builtin_ia32_si256_si ((__v4si)__A); 14,340 ( 1.91%) continue; 14,340 ( 1.91%) const uint32_t M2 = (M1 | M0) & 0x00ff00ff; 14,340 ( 1.91%) const uint32_t M0 = one_byte_bitmask & 0x55555555; 14,340 ( 1.91%) buf += 16; 14,340 ( 1.91%) return (__m256i)__builtin_ia32_psllwi256 ((__v16hi)__A, __B); 14,340 ( 1.91%) return (__m256i) __builtin_ia32_pblendvb256 ((__v32qi)__X, 6,340 ( 0.85%) uint32_t w = *buf++; 3,456 ( 0.46%) while (buf < end) { --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nimport struct\nrec = [0x4E00 + (i % 0x1000) for i in range(3200)]\nwith open(\"/tmp/prof/purecjk.bin\",\"wb\") as f:\n f.write(struct.pack(\"<I\",len(rec)))\n f.write(struct.pack(f\"<{len(rec)}H\",*rec))\nEOF\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.pure .build/runner /tmp/prof/purecjk.bin >/dev/null 2>&1\ngrep -E '^[0-9]+ [0-9]+' /tmp/prof/cg.pure | awk '{s+=$2} END {print s, s/3200 \" instr/unit\"}'"}

66877 20.8991 instr/unit --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | grep -c 'vpbroadcast\\|vmovd '\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | wc -l"}

26 410 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | grep -E 'vmovd |vpbroadcast|mov +\\$0x' | head -40"}

143d: mov $0xd800d800,%ecx 144d: vmovd %ecx,%xmm4 1472: vpbroadcastd %xmm4,%ymm4 1525: mov $0xffc0ffc,%ecx 153e: vmovd %ecx,%xmm0 1542: mov $0x40004000,%ecx 154d: vpbroadcastd %xmm0,%ymm0 1556: vmovd %ecx,%xmm0 155a: mov $0xc0e0c0e0,%ecx 155f: vpbroadcastd %xmm0,%ymm0 156d: vmovd %ecx,%xmm0 1571: mov $0x3f7f3f7f,%ecx 1576: vpbroadcastd %xmm0,%ymm0 157f: vmovd %ecx,%xmm0 1583: vpbroadcastd %xmm0,%ymm0 1604: mov $0x73f3f3f,%r9d 16bd: mov $0x0,%ecx 16c8: mov $0x73f3f3f,%ebx 17f0: mov $0xc080c080,%esi 17f5: vmovd %esi,%xmm12 17f9: mov $0x1f001f00,%esi 1804: vpbroadcastd %xmm12,%ymm12 1815: vmovd %esi,%xmm12 1823: vpbroadcastd %xmm12,%ymm12 19a0: mov $0x400040,%edx 19b3: vmovd %edx,%xmm12 19b7: mov $0x30003000,%edx 19c5: vmovd %edx,%xmm14 19c9: mov $0xf000f00,%edx 19ce: vpbroadcastd %xmm14,%ymm14 19d9: vpbroadcastd %xmm12,%ymm12 19ed: vmovd %edx,%xmm14 19f1: mov $0x80808080,%edx 19fb: vpbroadcastd %xmm14,%ymm14 1a00: vmovd %edx,%xmm15 1a04: mov $0x7000700,%edx 1a0e: vpbroadcastd %xmm15,%ymm15 1a3c: vmovd %edx,%xmm14 1a40: mov $0xf080f080,%edx 1a45: vpbroadcastd %xmm14,%ymm14 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nimport re\nsrc = open(\"submission/solve.c\").read()\n\nhelper = '''\n// Vector constants in .rodata: a memory-operand load is one instruction,\n// while GCC otherwise re-materializes each constant as mov+vmovd+vpbroadcastd.\n#define K16(name, val) \\\\\n static const uint16_t name##_arr[16] __attribute__((aligned(32))) = \\\\\n {val,val,val,val,val,val,val,val,val,val,val,val,val,val,val,val}; \\\\\n const __m256i name = _mm256_load_si256((const __m256i *)name##_arr)\n'''\nsrc = src.replace(\"#define INVALID ((size_t)-1)\", \"#define INVALID ((size_t)-1)\\n\" + helper)\nopen(\"submission/solve.c\",\"w\").write(src)\nEOF\necho done"}

done --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nsrc = open(\"submission/solve.c\").read()\n\n# top-of-function constants\nold = \"\"\" const __m256i v_ff80 = _mm256_set1_epi16((short)0xff80);\n const __m256i v_f800 = _mm256_set1_epi16((short)0xf800);\n const __m256i v_d800 = _mm256_set1_epi16((short)0xd800);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nnew = \"\"\" K16(v_ff80, 0xff80);\n K16(v_f800, 0xf800);\n K16(v_d800, 0xd800);\n K16(v_fc00, 0xfc00);\n K16(k_1f00, 0x1f00);\n K16(k_003f, 0x003f);\n K16(k_c080, 0xc080);\n K16(k_3f7f, 0x3f7f);\n K16(k_8000, 0x8000);\n K16(k_0ffc, 0x0ffc);\n K16(k_0140, 0x0140);\n K16(k_c0e0, 0xc0e0);\n K16(k_4000, 0x4000);\n K16(k_03ff, 0x03ff);\n K16(k_0040, 0x0040);\n K16(k_0700, 0x0700);\n K16(k_3000, 0x3000);\n K16(k_0f00, 0x0f00);\n K16(k_f080, 0xf080);\n K16(k_8080, 0x8080);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nassert old in src\nsrc = src.replace(old, new)\n\nold2 = \"\"\" const __m256i v_1f00 = _mm256_set1_epi16(0x1f00);\n const __m256i v_003f = _mm256_set1_epi16(0x003f);\n const __m256i v_c080 = _mm256_set1_epi16((short)0xc080);\n const __m256i t0 = _mm256_slli_epi16(v, 2);\n const __m256i t1 = _mm256_and_si256(t0, v_1f00);\n const __m256i t2 = _mm256_and_si256(v, v_003f);\n const __m256i t3 = _mm256_or_si256(t1, t2);\n const __m256i t4 = _mm256_or_si256(t3, v_c080);\"\"\"\nnew2 = \"\"\" const __m256i t0 = _mm256_slli_epi16(v, 2);\n const __m256i t1 = _mm256_and_si256(t0, k_1f00);\n const __m256i t2 = _mm256_and_si256(v, k_003f);\n const __m256i t3 = _mm256_or_si256(t1, t2);\n const __m256i t4 = _mm256_or_si256(t3, k_c080);\"\"\"\nassert old2 in src\nsrc = src.replace(old2, new2)\n\nold3 = \"\"\"#define VEC16(x) _mm256_set1_epi16((short)(x))\n const __m256i t0 = _mm256_shuffle_epi8(v, dup_even);\n const __m256i t1 = _mm256_and_si256(t0, VEC16(0x3f7f));\n const __m256i t2 = _mm256_or_si256(t1, VEC16(0x8000));\n\n const __m256i s0 = _mm256_srli_epi16(v, 4);\n const __m256i s1 = _mm256_and_si256(s0, VEC16(0x0ffc));\n const __m256i s2 = _mm256_maddubs_epi16(s1, VEC16(0x0140));\n const __m256i s3 = _mm256_or_si256(s2, VEC16(0xc0e0));\n const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask,\n VEC16(0x4000));\n const __m256i s4 = _mm256_xor_si256(s3, m0);\n#undef VEC16\"\"\"\nnew3 = \"\"\" const __m256i t0 = _mm256_shuffle_epi8(v, dup_even);\n const __m256i t1 = _mm256_and_si256(t0, k_3f7f);\n const __m256i t2 = _mm256_or_si256(t1, k_8000);\n\n const __m256i s0 = _mm256_srli_epi16(v, 4);\n const __m256i s1 = _mm256_and_si256(s0, k_0ffc);\n const __m256i s2 = _mm256_maddubs_epi16(s1, k_0140);\n const __m256i s3 = _mm256_or_si256(s2, k_c0e0);\n const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask,\n k_4000);\n const __m256i s4 = _mm256_xor_si256(s3, m0);\"\"\"\nassert old3 in src\nsrc = src.replace(old3, new3)\n\nold4 = \"\"\" const __m256i vfc = _mm256_and_si256(v, _mm256_set1_epi16((short)0xfc00));\"\"\"\nnew4 = \"\"\" const __m256i vfc = _mm256_and_si256(v, v_fc00);\"\"\"\nassert old4 in src\nsrc = src.replace(old4, new4)\n\nold5 = \"\"\"#define VEC16(x) _mm256_set1_epi16((short)(x))\n // prev = v shifted up by one lane (lane i gets unit i-1).\n const __m256i prev = _mm256_alignr_epi8(\n v, _mm256_permute2x128_si256(v, v, 0x08), 14);\n\n // High half: bytes [0 ... [3807 characters truncated for page size]

ok build 1.4s verify 2.0s PASS measure 1.2s 16,102,717 instructions (given: 77,764,322) SCORE +2.2718 (4.829x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.pure .build/runner /tmp/prof/purecjk.bin >/dev/null 2>&1\ngrep -E '^[0-9]+ [0-9]+' /tmp/prof/cg.pure | awk '{s+=$2} END {print s/3200 \" instr/unit\"}'\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' | grep -c 'vpbroadcast'"}

20.8991 instr/unit 13 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' > /tmp/dis.txt\ngrep -n 'vpbroadcast' /tmp/dis.txt; wc -l /tmp/dis.txt"}

21: 1472: vpbroadcastd %xmm4,%ymm4 67: 154d: vpbroadcastd %xmm0,%ymm0 71: 155f: vpbroadcastd %xmm0,%ymm0 76: 1576: vpbroadcastd %xmm0,%ymm0 79: 1583: vpbroadcastd %xmm0,%ymm0 233: 1804: vpbroadcastd %xmm12,%ymm12 240: 1823: vpbroadcastd %xmm12,%ymm12 339: 19ce: vpbroadcastd %xmm14,%ymm14 341: 19d9: vpbroadcastd %xmm12,%ymm12 348: 19fb: vpbroadcastd %xmm14,%ymm14 352: 1a0e: vpbroadcastd %xmm15,%ymm15 363: 1a45: vpbroadcastd %xmm14,%ymm14 369: 1a5e: vpbroadcastd %xmm14,%ymm14 410 /tmp/dis.txt --- Command finished with exit code: 0 ---

{"command": "sed -n 55,95p /tmp/dis.txt"}

1514: vpcmpeqw %ymm4,%ymm8,%ymm8 1518: vpmovmskb %ymm8,%ecx 151d: test %ecx,%ecx 151f: jne 1690 <utf16_to_utf8+0x270> 1525: mov $0xffc0ffc,%ecx 152a: vpshufb %ymm6,%ymm0,%ymm10 152f: add $0x20,%rdi 1533: and $0xaaaaaaaa,%edx 1539: vpsrlw $0x4,%ymm0,%ymm8 153e: vmovd %ecx,%xmm0 1542: mov $0x40004000,%ecx 1547: and $0x55555555,%esi 154d: vpbroadcastd %xmm0,%ymm0 1552: vpand %ymm0,%ymm8,%ymm8 1556: vmovd %ecx,%xmm0 155a: mov $0xc0e0c0e0,%ecx 155f: vpbroadcastd %xmm0,%ymm0 1564: vpmaddubsw %ymm5,%ymm8,%ymm8 1569: vpandn %ymm0,%ymm9,%ymm9 156d: vmovd %ecx,%xmm0 1571: mov $0x3f7f3f7f,%ecx 1576: vpbroadcastd %xmm0,%ymm0 157b: vpor %ymm0,%ymm8,%ymm8 157f: vmovd %ecx,%xmm0 1583: vpbroadcastd %xmm0,%ymm0 1588: vpxor %ymm9,%ymm8,%ymm8 158d: vpand %ymm0,%ymm10,%ymm0 1591: vpsllw $0xf,%ymm2,%ymm9 1596: vpor %ymm9,%ymm0,%ymm0 159b: vpunpcklwd %ymm8,%ymm0,%ymm9 15a0: vpunpckhwd %ymm8,%ymm0,%ymm0 15a5: or %esi,%edx 15a7: jne 1870 <utf16_to_utf8+0x450> 15ad: mov %r8,%rdx 15b0: vpshufb %ymm7,%ymm9,%ymm9 15b5: vpshufb %ymm7,%ymm0,%ymm0 15ba: add $0x30,%rax 15be: sub %rdi,%rdx 15c1: vmovdqu %xmm9,-0x30(%rax) 15c6: vmovdqu %xmm0,-0x24(%rax) 15cb: vextracti128 $0x1,%ymm9,-0x18(%rax) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-instr=yes --callgrind-out-file=/tmp/prof/cg.pure.instr .build/runner /tmp/prof/purecjk.bin >/dev/null 2>&1\ncallgrind_annotate --threshold=100 /tmp/prof/cg.pure.instr 2>/dev/null | head -30"}

-------------------------------------------------------------------------------- Profile data file '/tmp/prof/cg.pure.instr' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 38545 Trigger: Program termination Profiled target: .build/runner /tmp/prof/purecjk.bin (PID 895, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 100 Include dirs: User annotated: Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 11,613 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 7,172 (61.76%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:utf16_to_utf8 3,440 (29.62%) submission/solve.c:utf16_to_utf8 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner] 796 ( 6.85%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8 203 ( 1.75%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:utf16_to_utf8 2 ( 0.02%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/bmi2intrin.h:utf16_to_utf8 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nrm -f /tmp/prof/cg.*\nfor r in ascii latin cjk emoji purecjk; do\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.$r .build/runner /tmp/prof/$r.bin >/dev/null 2>&1 || echo \"$r FAILED\"\n echo -n \"$r: \"; grep -E '^[0-9]+ [0-9]+' /tmp/prof/cg.$r | awk '{s+=$2} END {print s}'\ndone", "timeout": 300000}

ascii: 916209 latin: 4182266 cjk: 6094944 emoji: 9394318 purecjk: 66877 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nimport re\nf = \".build/callgrind.runner.out\"\ncur_fn = None\nby_fn = {}\ncalls = {}\nfor line in open(f):\n ls = line.strip()\n m = re.match(r\"fn=\\((\\d+)\\)\\s*(.*)\", ls)\n if m:\n cur_fn = m.group(2) or m.group(1)\n continue\n if re.match(r\"^\\d+ \\d+$\", ls) or re.match(r\"^\\d+ \\d+ \", ls):\n by_fn[cur_fn] = by_fn.get(cur_fn, 0) + int(ls.split()[1])\nfor k,v in sorted(by_fn.items(), key=lambda kv:-kv[1])[:10]:\n print(v, k)\nprint(\"total\", sum(by_fn.values()))\nEOF"}

2869084 0x000000000001f100 2869084 694 2869084 main 2869084 696 2869084 716 1757297 utf16_to_utf8 total 16102717 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ncat > /tmp/selfcost.py <<'EOF'\nimport re, sys\nf = sys.argv[1]\ntarget = sys.argv[2] if len(sys.argv)>2 else \"utf16_to_utf8\"\ncur_fn = None\nself_cost = 0\nin_call = False\nfor line in open(f):\n ls = line.strip()\n m = re.match(r\"fn=\\(\\d+\\)\\s*(.*)\", ls)\n if m:\n cur_fn = m.group(1) or cur_fn\n continue\n if ls.startswith(\"calls=\"):\n in_call = True\n continue\n if re.match(r\"^[0-9+\\-*]+ \\d+\", ls):\n if in_call:\n in_call = False\n continue\n if cur_fn == target:\n self_cost += int(ls.split()[1])\nprint(self_cost)\nEOF\nfor r in ascii latin cjk emoji purecjk; do\n echo -n \"$r self: \"; python3 /tmp/selfcost.py /tmp/prof/cg.$r\ndone"}

ascii self: 166841 latin self: 749936 cjk self: 1076845 emoji self: 1674080 purecjk self: 11613 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nimport struct, random\ndef w(name, rec):\n with open(f\"/tmp/prof/{name}.bin\",\"wb\") as f:\n f.write(struct.pack(\"<I\",len(rec)))\n f.write(struct.pack(f\"<{len(rec)}H\",*rec))\nn=3200\nw(\"pure2\", [0x100 + (i%0x600) for i in range(n)])\nw(\"pureascii\", [0x20 + (i%0x5f) for i in range(n)])\nrec=[]\nfor i in range(n//2):\n cp = 0x10000 + (i % 0xF0000)\n cp -= 0x10000\n rec += [0xD800 + (cp>>10), 0xDC00 + (cp & 0x3FF)]\nw(\"puresurr\", rec)\n# mixed ascii+surrogate like emoji regime\nrng = random.Random(1)\nrec=[]\nwhile len(rec)<n:\n if rng.random()<0.4:\n rec += [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 rec += [0xD800+(cp>>10), 0xDC00+(cp&0x3FF)]\nif 0xD800 <= rec[-1] <= 0xDBFF: rec.pop()\nw(\"emojimix\", rec)\nprint(\"ok\")\nEOF\nfor r in pureascii pure2 purecjk puresurr emojimix; do\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.$r .build/runner /tmp/prof/$r.bin >/dev/null 2>&1\n echo -n \"$r self/unit: \"; python3 /tmp/selfcost.py /tmp/prof/cg.$r | awk -v n=3200 '{printf \"%.3f (%.1f/16blk)\\n\", $1/n, 16*$1/n}'\ndone", "timeout": 120000}

ok pureascii self/unit: 0.603 (9.7/16blk) pure2 self/unit: 3.143 (50.3/16blk) purecjk self/unit: 3.629 (58.1/16blk) puresurr self/unit: 6.618 (105.9/16blk) emojimix self/unit: 1.296 (20.7/16blk) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-instr=yes --callgrind-out-file=/tmp/prof/cg.psi .build/runner /tmp/prof/puresurr.bin >/dev/null 2>&1\ncallgrind_annotate --threshold=100 /tmp/prof/cg.psi 2>/dev/null | grep 'PROGRAM TOTALS'\n# count executed distinct instructions in fn\npython3 /tmp/selfcost.py /tmp/prof/cg.psi"}

21,178 (100.0%) PROGRAM TOTALS 23384 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --callgrind-out-file=/tmp/prof/cg.ps.line .build/runner /tmp/prof/puresurr.bin >/dev/null 2>&1\ncallgrind_annotate --auto=yes --threshold=99.9 /tmp/prof/cg.ps.line 2>/dev/null | awk '/Auto-annotated source: submission\\/solve.c/,0' | grep -E '\\([0-9. ]+%\\)' | head -40"}

4 ( 0.02%) size_t utf16_to_utf8(const uint16_t *restrict in, size_t n, uint8_t *restrict out) { 1 ( 0.00%) const uint16_t *end = in + n; 1 ( 0.00%) uint8_t *o = out; 803 ( 3.79%) while (end - buf >= 20) { 398 ( 1.88%) if (_mm256_testz_si256(v, v_ff80)) { 398 ( 1.88%) if (one_or_two_bytes_bitmask == 0xffffffff) { 2 ( 0.01%) const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0]; 398 ( 1.88%) if (surrogates_bitmask == 0) { 1 ( 0.00%) const uint8_t *row0 = &pack_1_2_3_utf8_bytes[(uint8_t)mask][0]; 199 ( 0.94%) const uint32_t Ml = surrogates_bitmask ^ Mh; 1,393 ( 6.58%) if (((one_byte_bitmask | surrogates_bitmask) == 0xffffffff) && 199 ( 0.94%) Ml == (uint32_t)(Mh << 2)) { 398 ( 1.88%) const uint32_t trailing_hi = Mh >> 31; 398 ( 1.88%) const uint32_t M0 = ob & 0x55555555; 597 ( 2.82%) const uint32_t M2 = ((M0 >> 7) | M0) & 0x00ff00ff; 597 ( 2.82%) const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0]; 597 ( 2.82%) const uint8_t *row_2 = &pack_1_2_utf8_bytes[(uint8_t)(M2 >> 16)][0]; 398 ( 1.88%) o += row[16]; 199 ( 0.94%) o += row_2[16]; 597 ( 2.82%) o -= trailing_hi; 597 ( 2.82%) buf += 16 - trailing_hi; 199 ( 0.94%) continue; 18 ( 0.08%) while (buf < end) { 24 ( 0.11%) uint32_t w = *buf++; 16 ( 0.08%) if (w < 0x80) { 16 ( 0.08%) } else if (w < 0x800) { 32 ( 0.15%) } else if ((w & 0xF800) != 0xD800) { 8 ( 0.04%) uint32_t hi = w - 0xD800; 32 ( 0.15%) if (hi > 0x3FF || buf == end) return INVALID; 24 ( 0.11%) uint32_t lo = (uint32_t)(*buf++) - 0xDC00; 16 ( 0.08%) if (lo > 0x3FF) return INVALID; 16 ( 0.08%) uint32_t cp = (hi << 10) + lo + 0x10000; 8 ( 0.04%) uint32_t be = _pdep_u32(cp, 0x073F3F3Fu) | 0xF0808080u; 8 ( 0.04%) uint32_t le = __builtin_bswap32(be); 8 ( 0.04%) memcpy(o, &le, 4); 16 ( 0.08%) o += 4; 1 ( 0.00%) return (size_t)(o - out); 2 ( 0.01%) } 199 ( 0.94%) return (__m256i) __builtin_ia32_vinsertf128_si256 ((__v8si)__X, 199 ( 0.94%) return *__P; --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ncat > submission/kconsts.c <<'EOF'\n// kconsts.c \u2014 vector constants in a separate TU so the compiler cannot\n// re-materialize them as mov+vmovd+vpbroadcastd triples inside hot loops.\n#include <stdint.h>\n\n#define ROW16(v) {v,v,v,v,v,v,v,v,v,v,v,v,v,v,v,v}\n\nconst uint16_t k16_tab[][16] __attribute__((aligned(32))) = {\n ROW16(0xff80), // 0\n ROW16(0xf800), // 1\n ROW16(0xd800), // 2\n ROW16(0xfc00), // 3\n ROW16(0x1f00), // 4\n ROW16(0x003f), // 5\n ROW16(0xc080), // 6\n ROW16(0x3f7f), // 7\n ROW16(0x8000), // 8\n ROW16(0x0ffc), // 9\n ROW16(0x0140), // 10\n ROW16(0xc0e0), // 11\n ROW16(0x4000), // 12\n ROW16(0x03ff), // 13\n ROW16(0x0040), // 14\n ROW16(0x0700), // 15\n ROW16(0x3000), // 16\n ROW16(0x0f00), // 17\n ROW16(0xf080), // 18\n ROW16(0x8080), // 19\n {0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e,\n 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e}, // 20 dup_even\n {0x0302, 0x0601, 0x0507, 0x0b0a, 0x0e09, 0x0d0f, 0xffff, 0xffff,\n 0x0302, 0x0601, 0x0507, 0x0b0a, 0x0e09, 0x0d0f, 0xffff, 0xffff}, // 21 sh3 (packed as u16)\n};\nEOF\necho ok"}

ok --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nsrc = open(\"submission/solve.c\").read()\n\nold_helper = src[src.index(\"// Vector constants in .rodata\"):src.index(\"__attribute__((target\"))]\nnew_helper = \"\"\"extern const uint16_t k16_tab[][16];\n#define KLOAD(i) _mm256_load_si256((const __m256i *)k16_tab[i])\n\n\"\"\"\nsrc = src.replace(old_helper, new_helper)\n\nold = \"\"\" K16(v_ff80, 0xff80);\n K16(v_f800, 0xf800);\n K16(v_d800, 0xd800);\n K16(v_fc00, 0xfc00);\n K16(k_1f00, 0x1f00);\n K16(k_003f, 0x003f);\n K16(k_c080, 0xc080);\n K16(k_3f7f, 0x3f7f);\n K16(k_8000, 0x8000);\n K16(k_0ffc, 0x0ffc);\n K16(k_0140, 0x0140);\n K16(k_c0e0, 0xc0e0);\n K16(k_4000, 0x4000);\n K16(k_03ff, 0x03ff);\n K16(k_0040, 0x0040);\n K16(k_0700, 0x0700);\n K16(k_3000, 0x3000);\n K16(k_0f00, 0x0f00);\n K16(k_f080, 0xf080);\n K16(k_8080, 0x8080);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nnew = \"\"\" const __m256i v_ff80 = KLOAD(0);\n const __m256i v_f800 = KLOAD(1);\n const __m256i v_d800 = KLOAD(2);\n const __m256i v_fc00 = KLOAD(3);\n const __m256i k_1f00 = KLOAD(4);\n const __m256i k_003f = KLOAD(5);\n const __m256i k_c080 = KLOAD(6);\n const __m256i k_3f7f = KLOAD(7);\n const __m256i k_8000 = KLOAD(8);\n const __m256i k_0ffc = KLOAD(9);\n const __m256i k_0140 = KLOAD(10);\n const __m256i k_c0e0 = KLOAD(11);\n const __m256i k_4000 = KLOAD(12);\n const __m256i k_03ff = KLOAD(13);\n const __m256i k_0040 = KLOAD(14);\n const __m256i k_0700 = KLOAD(15);\n const __m256i k_3000 = KLOAD(16);\n const __m256i k_0f00 = KLOAD(17);\n const __m256i k_f080 = KLOAD(18);\n const __m256i k_8080 = KLOAD(19);\n const __m256i dup_even = KLOAD(20);\n const __m256i k_sh3 = KLOAD(21);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nassert old in src\nsrc = src.replace(old, new)\n\nold2 = \"\"\" static const uint16_t dup_even_arr[16] __attribute__((aligned(32))) = {\n 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e,\n 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e};\n const __m256i dup_even = _mm256_load_si256((const __m256i *)dup_even_arr);\n\"\"\"\nassert old2 in src\nsrc = src.replace(old2, \"\")\n\nold3 = \"\"\" static const int8_t sh3_arr[32] __attribute__((aligned(32))) = {\n 2,3,1, 6,7,5, 10,11,9, 14,15,13, -1,-1,-1,-1,\n 2,3,1, 6,7,5, 10,11,9, 14,15,13, -1,-1,-1,-1};\n const __m256i sh3 = _mm256_load_si256((const __m256i *)sh3_arr);\n const __m256i u02 = _mm256_shuffle_epi8(out0, sh3);\n const __m256i u13 = _mm256_shuffle_epi8(out1, sh3);\"\"\"\nnew3 = \"\"\" const __m256i u02 = _mm256_shuffle_epi8(out0, k_sh3);\n const __m256i u13 = _mm256_shuffle_epi8(out1, k_sh3);\"\"\"\nassert old3 in src\nsrc = src.replace(old3, new3)\n\nopen(\"submission/solve.c\",\"w\").write(src)\nprint(\"ok\")\nEOF\n./grade", "timeout": 600000}

File "<stdin>", line 3 old_helper = src[src.index("// Vector constants in .rodata"):src.index("__attribute__((target"))] ^ SyntaxError: closing parenthesis ')' does not match opening parenthesis '[' build 1.5s verify 1.9s PASS measure 1.3s 16,185,647 instructions (given: 78,178,224) SCORE +2.2721 (4.830x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\npython3 - <<'EOF'\nsrc = open(\"submission/solve.c\").read()\n\ni = src.index(\"// Vector constants in .rodata\")\nj = src.index(\"__attribute__((target\")\nold_helper = src[i:j]\nnew_helper = \"\"\"extern const uint16_t k16_tab[][16];\n#define KLOAD(i) _mm256_load_si256((const __m256i *)k16_tab[i])\n\n\"\"\"\nsrc = src.replace(old_helper, new_helper)\n\nold = \"\"\" K16(v_ff80, 0xff80);\n K16(v_f800, 0xf800);\n K16(v_d800, 0xd800);\n K16(v_fc00, 0xfc00);\n K16(k_1f00, 0x1f00);\n K16(k_003f, 0x003f);\n K16(k_c080, 0xc080);\n K16(k_3f7f, 0x3f7f);\n K16(k_8000, 0x8000);\n K16(k_0ffc, 0x0ffc);\n K16(k_0140, 0x0140);\n K16(k_c0e0, 0xc0e0);\n K16(k_4000, 0x4000);\n K16(k_03ff, 0x03ff);\n K16(k_0040, 0x0040);\n K16(k_0700, 0x0700);\n K16(k_3000, 0x3000);\n K16(k_0f00, 0x0f00);\n K16(k_f080, 0xf080);\n K16(k_8080, 0x8080);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nnew = \"\"\" const __m256i v_ff80 = KLOAD(0);\n const __m256i v_f800 = KLOAD(1);\n const __m256i v_d800 = KLOAD(2);\n const __m256i v_fc00 = KLOAD(3);\n const __m256i k_1f00 = KLOAD(4);\n const __m256i k_003f = KLOAD(5);\n const __m256i k_c080 = KLOAD(6);\n const __m256i k_3f7f = KLOAD(7);\n const __m256i k_8000 = KLOAD(8);\n const __m256i k_0ffc = KLOAD(9);\n const __m256i k_0140 = KLOAD(10);\n const __m256i k_c0e0 = KLOAD(11);\n const __m256i k_4000 = KLOAD(12);\n const __m256i k_03ff = KLOAD(13);\n const __m256i k_0040 = KLOAD(14);\n const __m256i k_0700 = KLOAD(15);\n const __m256i k_3000 = KLOAD(16);\n const __m256i k_0f00 = KLOAD(17);\n const __m256i k_f080 = KLOAD(18);\n const __m256i k_8080 = KLOAD(19);\n const __m256i dup_even = KLOAD(20);\n const __m256i k_sh3 = KLOAD(21);\n const __m256i v_0000 = _mm256_setzero_si256();\n\"\"\"\nassert old in src\nsrc = src.replace(old, new)\n\nold2 = \"\"\" static const uint16_t dup_even_arr[16] __attribute__((aligned(32))) = {\n 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e,\n 0x0000, 0x0202, 0x0404, 0x0606, 0x0808, 0x0a0a, 0x0c0c, 0x0e0e};\n const __m256i dup_even = _mm256_load_si256((const __m256i *)dup_even_arr);\n\"\"\"\nassert old2 in src\nsrc = src.replace(old2, \"\")\n\nold3 = \"\"\" static const int8_t sh3_arr[32] __attribute__((aligned(32))) = {\n 2,3,1, 6,7,5, 10,11,9, 14,15,13, -1,-1,-1,-1,\n 2,3,1, 6,7,5, 10,11,9, 14,15,13, -1,-1,-1,-1};\n const __m256i sh3 = _mm256_load_si256((const __m256i *)sh3_arr);\n const __m256i u02 = _mm256_shuffle_epi8(out0, sh3);\n const __m256i u13 = _mm256_shuffle_epi8(out1, sh3);\"\"\"\nnew3 = \"\"\" const __m256i u02 = _mm256_shuffle_epi8(out0, k_sh3);\n const __m256i u13 = _mm256_shuffle_epi8(out1, k_sh3);\"\"\"\nassert old3 in src\nsrc = src.replace(old3, new3)\n\nopen(\"submission/solve.c\",\"w\").write(src)\nprint(\"ok\")\nEOF\n./grade", "timeout": 600000}

ok build 1.5s verify 2.0s PASS measure 1.2s 13,304,728 instructions (given: 77,998,560) SCORE +2.5515 (5.862x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ngit init -q 2>/dev/null; git add -A; git commit -qm \"AVX2 simdutf-style transcoder: +2.55 (5.86x)\" 2>&1 | tail -1\nfor r in pureascii pure2 purecjk puresurr emojimix ascii latin cjk emoji; do\n valgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --dump-line=no --callgrind-out-file=/tmp/prof/cg.$r .build/runner /tmp/prof/$r.bin >/dev/null 2>&1\n echo -n \"$r: \"; python3 /tmp/selfcost.py /tmp/prof/cg.$r\ndone", "timeout": 300000}

fatal: unable to auto-detect email address (got 'root@modal.(none)') pureascii: 525 pure2: 8467 purecjk: 8827 puresurr: 16801 emojimix: 16777 ascii: 159240 latin: 635179 cjk: 863335 emoji: 532348 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ngit config user.email [email protected]; git config user.name \"jcode bench\"; git add -A; git commit -qm \"AVX2 simdutf-style transcoder: +2.55 (5.86x)\"\nfor r in pureascii pure2 purecjk puresurr emojimix; do\n echo -n \"$r total: \"; grep -E '^[0-9+-]+ [0-9]+' /tmp/prof/cg.$r | awk '{s+=$2} END {print s, s/3200}'\ndone"}

pureascii total: 11004 3.43875 pure2 total: 50802 15.8756 purecjk total: 52962 16.5506 puresurr total: 100806 31.5019 emojimix total: 100662 31.4569 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nobjdump -d .build/runner --no-show-raw-insn | awk '/<utf16_to_utf8>:/,/^$/' > /tmp/dis.txt; wc -l /tmp/dis.txt; sed -n 1,120p /tmp/dis.txt"}

366 /tmp/dis.txt 0000000000001420 <utf16_to_utf8>: 1420: push %rbp 1421: mov %rdx,%r11 1424: lea (%rsi,%rsi,1),%rdx 1428: lea (%rdi,%rsi,2),%r8 142c: mov %rsp,%rbp 142f: sub $0x18,%rsp 1433: cmp $0x26,%rdx 1437: jle 1a59 <utf16_to_utf8+0x639> 143d: mov %rbx,-0x18(%rbp) 1441: vmovdqu 0xbd7(%rip),%ymm2 # 2020 <k16_tab> 1449: mov %r11,%rax 144c: vpxor %xmm3,%xmm3,%xmm3 1450: mov %r12,-0x10(%rbp) 1454: vmovdqu 0xbe4(%rip),%ymm5 # 2040 <k16_tab+0x20> 145c: mov $0x73f3f3f,%ebx 1461: lea 0xe78(%rip),%r10 # 22e0 <pack_1_2_3_utf8_bytes> 1468: mov %r13,-0x8(%rbp) 146c: vmovdqu 0xbec(%rip),%ymm4 # 2060 <k16_tab+0x40> 1474: lea 0x2e65(%rip),%r9 # 42e0 <pack_1_2_utf8_bytes> 147b: vmovdqu 0xc7d(%rip),%ymm13 # 2100 <k16_tab+0xe0> 1483: vmovdqu 0xc95(%rip),%ymm12 # 2120 <k16_tab+0x100> 148b: vmovdqu 0xcad(%rip),%ymm11 # 2140 <k16_tab+0x120> 1493: vmovdqu 0xcc5(%rip),%ymm9 # 2160 <k16_tab+0x140> 149b: vmovdqu 0xcdd(%rip),%ymm10 # 2180 <k16_tab+0x160> 14a3: jmp 14f0 <utf16_to_utf8+0xd0> 14a5: nopl (%rax) 14a8: cmp $0x3e,%rdx 14ac: jle 1630 <utf16_to_utf8+0x210> 14b2: vmovdqu 0x20(%rdi),%ymm1 14b7: vptest %ymm2,%ymm1 14bc: jne 1630 <utf16_to_utf8+0x210> 14c2: vpackuswb %ymm1,%ymm0,%ymm1 14c6: add $0x40,%rdi 14ca: add $0x20,%rax 14ce: vpermq $0xd8,%ymm1,%ymm1 14d4: vmovdqu %ymm1,-0x20(%rax) 14d9: nopl 0x0(%rax) 14e0: mov %r8,%rdx 14e3: sub %rdi,%rdx 14e6: cmp $0x26,%rdx 14ea: jle 15c0 <utf16_to_utf8+0x1a0> 14f0: vmovdqu (%rdi),%ymm0 14f4: vptest %ymm2,%ymm0 14f9: je 14a8 <utf16_to_utf8+0x88> 14fb: vpand %ymm0,%ymm2,%ymm1 14ff: vpcmpeqw %ymm3,%ymm1,%ymm7 1503: vpand %ymm0,%ymm5,%ymm1 1507: vpcmpeqw %ymm3,%ymm1,%ymm6 150b: vpmovmskb %ymm7,%esi 150f: vpmovmskb %ymm6,%edx 1513: cmp $0xffffffff,%edx 1516: je 1790 <utf16_to_utf8+0x370> 151c: vpcmpeqw %ymm1,%ymm4,%ymm1 1520: vpmovmskb %ymm1,%ecx 1524: test %ecx,%ecx 1526: jne 1650 <utf16_to_utf8+0x230> 152c: and $0xaaaaaaaa,%edx 1532: and $0x55555555,%esi 1538: add $0x20,%rdi 153c: vpshufb 0xd5b(%rip),%ymm0,%ymm1 # 22a0 <k16_tab+0x280> 1545: vpsrlw $0x4,%ymm0,%ymm0 154a: vpandn 0xc4e(%rip),%ymm6,%ymm6 # 21a0 <k16_tab+0x180> 1552: vpand %ymm0,%ymm11,%ymm0 1556: vpand %ymm1,%ymm13,%ymm1 155a: vpmaddubsw %ymm9,%ymm0,%ymm0 155f: vpor %ymm12,%ymm1,%ymm1 1564: vpor %ymm0,%ymm10,%ymm0 1568: vpxor %ymm6,%ymm0,%ymm0 156c: vpunpcklwd %ymm0,%ymm1,%ymm6 1570: vpunpckhwd %ymm0,%ymm1,%ymm1 1574: or %esi,%edx 1576: jne 1810 <utf16_to_utf8+0x3f0> 157c: vpshufb 0xd3b(%rip),%ymm6,%ymm6 # 22c0 <k16_tab+0x2a0> 1585: mov %r8,%rdx 1588: add $0x30,%rax 158c: vpshufb 0xd2b(%rip),%ymm1,%ymm1 # 22c0 <k16_tab+0x2a0> 1595: sub %rdi,%rdx 1598: vmovdqu %xmm6,-0x30(%rax) 159d: vmovdqu %xmm1,-0x24(%rax) 15a2: vextracti128 $0x1,%ymm6,-0x18(%rax) 15a9: vextracti128 $0x1,%ymm1,-0xc(%rax) 15b0: cmp $0x26,%rdx 15b4: jg 14f0 <utf16_to_utf8+0xd0> 15ba: nopw 0x0(%rax,%rax,1) 15c0: vzeroupper 15c3: mov -0x18(%rbp),%rbx 15c7: mov -0x10(%rbp),%r12 15cb: mov -0x8(%rbp),%r13 15cf: cmp %r8,%rdi 15d2: jae 1627 <utf16_to_utf8+0x207> 15d4: mov $0x73f3f3f,%r9d 15da: jmp 15ee <utf16_to_utf8+0x1ce> 15dc: nopl 0x0(%rax) 15e0: mov %cl,(%rax) 15e2: mov %rsi,%rdi 15e5: add $0x1,%rax 15e9: cmp %r8,%rdi 15ec: jae 1627 <utf16_to_utf8+0x207> 15ee: movzwl (%rdi),%ecx 15f1: lea 0x2(%rdi),%rsi 15f5: mov %ecx,%edx 15f7: cmp $0x7f,%cx 15fb: jbe 15e0 <utf16_to_utf8+0x1c0> 15fd: cmp $0x7ff,%ecx 1603: ja 18a0 <utf16_to_utf8+0x480> 1609: shr $0x6,%ecx 160c: and $0x3f,%edx 160f: mov %rsi,%rdi 1612: add $0x2,%rax 1616: or $0xffffffc0,%ecx 1619: or $0xffffff80,%edx 161c: mov %cl,-0x2(%rax) 161f: mov %dl,-0x1(%rax) 1622: cmp %r8,%rdi 1625: jb 15ee <utf16_to_utf8+0x1ce> 1627: leave 1628: sub %r11,%rax 162b: ret 162c: nopl 0x0(%rax) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\ngrep -E '^(fn|fl|ob)=' /tmp/prof/cg.purecjk | sort | uniq -c | sort -rn | head; echo ----\ncallgrind_annotate /tmp/prof/cg.purecjk 2>/dev/null | sed -n '/file:function/,/^$/p' | head -15"}

1 ob=(6) 1 ob=(2) /usr/lib/libc.so.6 1 ob=(1) /usr/lib/ld-linux-x86-64.so.2 1 fn=(912) utf16_to_utf8 1 fn=(724) 1 fn=(716) (below main) 1 fn=(696) __libc_start_main@@GLIBC_2.34 1 fn=(694) (below main) 1 fn=(0) 0x000000000001f100 1 fl=(241) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/submission/solve.c ---- Ir file:function -------------------------------------------------------------------------------- 4,579 (51.87%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:utf16_to_utf8 3,241 (36.72%) submission/solve.c:utf16_to_utf8 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode/.build/runner] 796 ( 9.02%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/emmintrin.h:utf16_to_utf8 208 ( 2.36%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:utf16_to_utf8 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-fable-5-utf16-transcode/tasks/utf16-transcode\nvalgrind --tool=callgrind --toggle-collect=utf16_to_utf8 --collect-atstart=no --callgrind-out-file=/tmp/prof/cg.em.ann .build/runner /tmp/prof/emojimix.bin >/dev/null 2>&1\ncallgrind_annotate --auto=yes --threshold=99.9 /tmp/prof/cg.em.ann 2>/dev/null | awk '/Auto-annotated source: submission\\/solve.c/,0' | grep -E '\\([0-9. ]+%\\)' | sort -t'(' -k2 -rn | head -30"}

16,767 (99.94%) events annotated 1,584 ( 9.44%) if (((one_byte_bitmask | surrogates_bitmask) == 0xffffffff) && 990 ( 5.90%) const uint32_t trailing_hi = Mh >> 31; 820 ( 4.89%) while (end - buf >= 20) { 594 ( 3.54%) o -= trailing_hi; 594 ( 3.54%) const uint8_t *row_2 = &pack_1_2_utf8_bytes[(uint8_t)(M2 >> 16)][0]; 594 ( 3.54%) const uint8_t *row = &pack_1_2_utf8_bytes[(uint8_t)M2][0]; 594 ( 3.54%) buf += 16 - trailing_hi; 406 ( 2.42%) if (_mm256_testz_si256(v, v_ff80)) { 401 ( 2.39%) *__P = __B; 396 ( 2.36%) if (surrogates_bitmask == 0) { 396 ( 2.36%) if (one_or_two_bytes_bitmask == 0xffffffff) { 396 ( 2.36%) o += row[16]; 396 ( 2.36%) const uint32_t M2 = ((M0 >> 7) | M0) & 0x00ff00ff; 396 ( 2.36%) const uint32_t M0 = ob & 0x55555555; 198 ( 1.18%) const uint32_t Ml = surrogates_bitmask ^ Mh; 198 ( 1.18%) o += row_2[16]; 198 ( 1.18%) continue; 198 ( 1.18%) Ml == (uint32_t)(Mh << 2)) { 28 ( 0.17%) } else if ((w & 0xF800) != 0xD800) { 28 ( 0.17%) if (hi > 0x3FF || buf == end) return INVALID; 21 ( 0.13%) uint32_t w = *buf++; 21 ( 0.13%) uint32_t lo = (uint32_t)(*buf++) - 0xDC00; 16 ( 0.10%) while (buf < end) { 14 ( 0.08%) } else if (w < 0x800) { 14 ( 0.08%) if (w < 0x80) { 14 ( 0.08%) uint32_t cp = (hi << 10) + lo + 0x10000; 14 ( 0.08%) o += 4; 14 ( 0.08%) if (lo > 0x3FF) return INVALID; 10 ( 0.06%) if (end - buf >= 32) { --- Command finished with exit code: 0 ---