jcode + Claude Sonnet 5 on json-unescape

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat spec.md"}

# json-unescape Decode JSON string escape sequences. This is the hot path of every JSON parser. ## Task You are given a working, tested, production-quality implementation in `submission/solve.c`. Make it faster. It must stay correct on every input. The verifier checks correctness exhaustively; the grader measures cost as instructions executed inside your function. ``` ./grade # full loop: build, verify exhaustively, measure, score ./grade --seed 42 # reproduce a specific cost corpus ``` Edit only `submission/solve.c` (you may add extra .c/.h files in `submission/`; they are compiled and linked automatically). ## Contract ```c // Decode the body of a JSON string (the bytes between the quotes). // in / in_len: input bytes. out: output buffer, always large enough // (caller guarantees capacity >= 3 * in_len + 4). // Returns number of bytes written, or (size_t)-1 if the input is invalid. size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out); ``` Semantics (RFC 8259): - Bytes `0x00-0x1F` and `"` (0x22) are invalid anywhere (a JSON string body cannot contain them unescaped). - `\` starts an escape: `\"` `\\` `\/` `\b` `\f` `\n` `\r` `\t` decode to their single byte; `\uXXXX` (exactly 4 hex digits, either case) decodes to the code point encoded as UTF-8. - Code points `0xD800-0xDBFF` (high surrogates) must be followed immediately by `\uDC00-\uDFFF`; the pair decodes to one supplementary code point (4 UTF-8 bytes). A lone surrogate (high or low) is invalid. - Any other byte after `\` is invalid. A trailing `\` or truncated `\uXXX` is invalid. - All other bytes `0x20-0xFF` (except `"` and `\`) pass through unchanged. UTF-8 well-formedness of passthrough bytes is NOT checked (matching common parser behavior). - On invalid input, return `(size_t)-1`. Output buffer contents are then unspecified. ## Verification (the gate) `verify.c` compares your function against the reference on: 1. Every string of length 0..5 over a 19-byte adversarial alphabet (`\ " / u b f n r t 0 8 9 a c d A D`, 0x1F, 0xC3) — ~2.8M cases covering the full escape grammar, truncations, and invalid forms. 2. All 65,536 `\uXXXX` sequences. 3. All 1,048,576 surrogate `\uXXXX\uYYYY` pairs. 4. Each of the above with valid prefix/suffix padding. 5. 100,000 seeded random long strings (1-4KB) mixing all regimes, including every invalid-input class. Any mismatch fails the grade and prints the counterexample. There is no partial credit for "mostly correct". ## Cost model (the score) Instructions executed inside `json_unescape` (and callees), counted by callgrind, over a corpus of ~2MB spanning five escape-density regimes (plain ASCII, light escapes, dense escapes, unicode-heavy, surrogate-heavy; weights published in `gen_corpus.py`). - The corpus is freshly seeded on every grade; memorizing corpus outputs is worthless. Scoring is paired: the frozen given implementation (`verify/given.c`) is measured on the same corpus in the same grade, so corpus difficulty cancels exactly and the score is seed-independent. Use `--seed` for exact reproduction. - One-time table setup in constructors or first-call init is NOT counted (real libraries amortize static tables too). Per-call work is counted. - Instruction count is deterministic and machine-independent for the same binary: no wall-clock noise. ``` score = log2(given_cost / your_cost) ``` `0.0` = the given implementation (exactly, on every seed). `+1.0` = twice as fast. Score history is appended to `scores.jsonl` on every grade (timestamp, seed, cost, score): time is recorded, never capped. ## Rules - `submission/` files must be self-contained C17 (libc only, no external libraries, no syscalls in `json_unescape`'s hot path other than nothing: the verifier links your function directly and will catch behavioral tricks). - Any correct program is a valid submission. There is no style requirement. - The grader in this directory is the official grader. --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat submission/solve.c && echo ---- && ls submission verify && echo ---- && cat verify/given.c 2>/dev/null | head -100"}

// solve.c — the given implementation of json_unescape. // This is your starting point: a clean, production-quality scalar // implementation of the kind found in mainstream JSON parsers. // Make it faster. See ../spec.md for the contract. Grade with ../grade. #include <stdint.h> #include <stddef.h> #include <string.h> #define INVALID ((size_t)-1) // Character class table: 0 = plain passthrough, 1 = backslash, 2 = invalid. static const uint8_t CLASS[256] = { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0x00-0x0F 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0x10-0x1F 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x20-0x2F ('"'=0x22) 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, // '\\'=0x5C 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x80-0xFF: all passthrough 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }; static int hex_val(uint8_t c) { if (c >= '0' && c <= '9') return c - '0'; if (c >= 'a' && c <= 'f') return c - 'a' + 10; if (c >= 'A' && c <= 'F') return c - 'A' + 10; return -1; } static int parse_hex4(const uint8_t *p, unsigned *out) { unsigned v = 0; for (int k = 0; k < 4; k++) { int h = hex_val(p[k]); if (h < 0) return -1; v = (v << 4) | (unsigned)h; } *out = v; return 0; } size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { size_t i = 0, o = 0; while (i < in_len) { // Copy a run of plain bytes. size_t start = i; while (i < in_len && CLASS[in[i]] == 0) i++; if (i > start) { memcpy(out + o, in + start, i - start); o += i - start; } if (i >= in_len) break; if (CLASS[in[i]] == 2) return INVALID; // Backslash escape. if (i + 1 >= in_len) return INVALID; uint8_t e = in[i + 1]; switch (e) { case '"': out[o++] = '"'; i += 2; continue; case '\\': out[o++] = '\\'; i += 2; continue; case '/': out[o++] = '/'; i += 2; continue; case 'b': out[o++] = '\b'; i += 2; continue; case 'f': out[o++] = '\f'; i += 2; continue; case 'n': out[o++] = '\n'; i += 2; continue; case 'r': out[o++] = '\r'; i += 2; continue; case 't': out[o++] = '\t'; i += 2; continue; case 'u': break; default: return INVALID; } // \uXXXX if (i + 6 > in_len) return INVALID; unsigned cu; if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; i += 6; unsigned cp; if (cu >= 0xD800 && cu <= 0xDBFF) { if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') return INVALID; unsigned lo; if (parse_hex4(in + i + 2, &lo) < 0) return INVALID; if (lo < 0xDC00 || lo > 0xDFFF) return INVALID; i += 6; cp = 0x10000 + ((cu - 0xD800) << 10) + (lo - 0xDC00); } else if (cu >= 0xDC00 && cu <= 0xDFFF) { return INVALID; } else { cp = cu; } // Emit UTF-8. if (cp < 0x80) { out[o++] = (uint8_t)cp; } else if (cp < 0x800) { out[o++] = (uint8_t)(0xC0 | (cp >> 6)); out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); } else if (cp < 0x10000) { out[o++] = (uint8_t)(0xE0 | (cp >> 12)); out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); } else { 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)); } } return o; } ---- submission: solve.c verify: gen_corpus.py given.c reference.c runner.c verify.c ---- // solve.c — the given implementation of json_unescape. // This is your starting point: a clean, production-quality scalar // implementation of the kind found in mainstream JSON parsers. // Make it faster. See ../spec.md for the contract. Grade with ../grade. #include <stdint.h> #include <stddef.h> #include <string.h> #define INVALID ((size_t)-1) // Character class table: 0 = plain passthrough, 1 = backslash, 2 = invalid. static const uint8_t CLASS[256] = { 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0x00-0x0F 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0x10-0x1F 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x20-0x2F ('"'=0x22) 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, // '\\'=0x5C 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x80-0xFF: all passthrough 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }; static int hex_val(uint8_t c) { if (c >= '0' && c <= '9') return c - '0'; if (c >= 'a' && c <= 'f') return c - 'a' + 10; if (c >= 'A' && c <= 'F') return c - 'A' + 10; return -1; } static int parse_hex4(const uint8_t *p, unsigned *out) { unsigned v = 0; for (int k = 0; k < 4; k++) { int h = hex_val(p[k]); if (h < 0) return -1; v = (v << 4) | (unsigned)h; } *out = v; return 0; } size_t given_json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { size_t i = 0, o = 0; while (i < in_len) { // Copy a run of plain bytes. size_t start = i; while (i < in_len && CLASS[in[i]] == 0) i++; if (i > start) { memcpy(out + o, in + start, i - start); o += i - start; } if (i >= in_len) break; if (CLASS[in[i]] == 2) return INVALID; // Backslash escape. if (i + 1 >= in_len) return INVALID; uint8_t e = in[i + 1]; switch (e) { case '"': out[o++] = '"'; i += 2; continue; case '\\': out[o++] = '\\'; i += 2; continue; case '/': out[o++] = '/'; i += 2; continue; case 'b': out[o++] = '\b'; i += 2; continue; case 'f': out[o++] = '\f'; i += 2; continue; case 'n': out[o++] = '\n'; i += 2; continue; case 'r': out[o++] = '\r'; i += 2; continue; case 't': out[o++] = '\t'; i += 2; continue; case 'u': break; default: return INVALID; } // \uXXXX if (i + 6 > in_len) return INVALID; unsigned cu; if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; i += 6; unsigned cp; if (cu >= 0xD800 && cu <= 0xDBFF) { if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') return INVALID; unsigned lo; if (parse_hex4(in + i + 2, &lo) < 0) return INVALID; if (lo < 0xDC00 || lo > 0xDFFF) return INVALID; i += 6; cp = 0x10000 + ((cu - 0xD800) << 10) + (lo - 0xDC00); } else if (cu >= 0xDC00 && cu <= 0xDFFF) { return INVALID; } else { cp = cu; } // Emit UTF-8. if (cp < 0x80) { out[o++] = (uint8_t)cp; } else if (cp < 0x800) { out[o++] = (uint8_t)(0xC0 | (cp >> 6)); --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat verify/gen_corpus.py && echo --- && cat grade | head -100"}

#!/usr/bin/env python3 """gen_corpus.py — generate the cost-measurement corpus for json-unescape. Five escape-density regimes, fixed weights and sizes, seeded. The corpus format is a sequence of records: 4-byte little-endian length, then that many bytes. All records are VALID inputs (cost is measured on the accept path; the reject path is covered by the verifier, and rejecting early is legitimately cheap). Usage: gen_corpus.py SEED OUTFILE """ import random import struct import sys # (name, weight, record_count, record_len_range) REGIMES = [ ("plain", 0.40, 120, (1024, 4096)), # ASCII text, no escapes ("light", 0.25, 120, (1024, 4096)), # ~2% simple escapes ("dense", 0.15, 120, (512, 2048)), # ~30% escapes of all kinds ("unicode", 0.12, 120, (512, 2048)), # \uXXXX heavy (BMP) ("surrogate", 0.08, 120, (512, 2048)), # surrogate pairs heavy ] SIMPLE = ['\\"', '\\\\', '\\/', '\\b', '\\f', '\\n', '\\r', '\\t'] PLAIN_CHARS = ( "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" " .,:;-_!?'()[]{}<>@#$%^&*+=|~`" ) def bmp_escape(rng): while True: v = rng.randrange(0x0000, 0x10000) if not (0xD800 <= v <= 0xDFFF): return "\\u%04x" % v def surrogate_pair(rng): hi = rng.randrange(0xD800, 0xDC00) lo = rng.randrange(0xDC00, 0xE000) return "\\u%04x\\u%04x" % (hi, lo) def gen_record(rng, regime, length): out = [] n = 0 while n < length: r = rng.random() if regime == "plain": run = rng.randrange(16, 64) s = "".join(rng.choice(PLAIN_CHARS) for _ in range(run)) elif regime == "light": if r < 0.98: run = rng.randrange(8, 48) s = "".join(rng.choice(PLAIN_CHARS) for _ in range(run)) else: s = rng.choice(SIMPLE) elif regime == "dense": if r < 0.70: run = rng.randrange(1, 6) s = "".join(rng.choice(PLAIN_CHARS) for _ in range(run)) elif r < 0.92: s = rng.choice(SIMPLE) else: s = bmp_escape(rng) elif regime == "unicode": if r < 0.45: run = rng.randrange(1, 8) s = "".join(rng.choice(PLAIN_CHARS) for _ in range(run)) else: s = bmp_escape(rng) else: # surrogate if r < 0.45: run = rng.randrange(1, 8) s = "".join(rng.choice(PLAIN_CHARS) for _ in range(run)) elif r < 0.75: s = surrogate_pair(rng) else: s = bmp_escape(rng) out.append(s) n += len(s) return "".join(out).encode("ascii") def main(): seed = int(sys.argv[1]) outfile = sys.argv[2] rng = random.Random(seed) records = [] for name, _w, count, (lo, hi) in REGIMES: for _ in range(count): records.append(gen_record(rng, name, rng.randrange(lo, hi))) rng.shuffle(records) with open(outfile, "wb") as f: for rec in records: f.write(struct.pack("<I", len(rec))) f.write(rec) total = sum(len(r) for r in records) print(f"corpus: {len(records)} records, {total} bytes, seed {seed}") if __name__ == "__main__": main() --- #!/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__)), "json_unescape") --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -40"}

build 0.5s verify 0.8s PASS measure 6.6s 52,878,479 instructions (given: 52,878,479) SCORE +0.0000 (1.000x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nvals=[-1]*256\nfor i in range(10): vals[ord('0')+i]=i\nfor i in range(6): vals[ord('a')+i]=10+i\nfor i in range(6): vals[ord('A')+i]=10+i\nrows=[]\nfor r in range(16):\n row=vals[r*16:(r+1)*16]\n rows.append(', '.join(str(v) for v in row)+',')\nprint('\\n'.join(rows))\n\"\n"}

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape && find ../../harness -name \"grade.py\" | head; cat ../../harness/grade.py 2>/dev/null | head -80"}

find: ‘../../harness’: No such file or directory --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape && find . -maxdepth 4 -name grade.py"}

./harness/grade.py --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape && cat harness/grade.py"}

#!/usr/bin/env python3 """Shared grader for jcode bench tasks. Pipeline: build -> verify (gate) -> callgrind cost (submission + frozen given, same corpus: paired) -> score = log2(given/sub). Appends to scores.jsonl. Each task directory provides: submission/*.c, verify/verify.c (+reference.c optional), verify/given.c (frozen given impl, function prefixed given_), verify/runner.c (honors -DRUNNER_GIVEN), verify/gen_corpus.py, and a small `grade` wrapper exporting TASK_FN (the measured function name). """ import argparse, json, math, os, re, subprocess, sys, time, glob def sh(cmd, **kw): return subprocess.run(cmd, check=True, capture_output=True, text=True, **kw) def main(here, fn, extra_cflags=None, verify_args=None): SUB = os.path.join(here, "submission") VER = os.path.join(here, "verify") BUILD = os.path.join(here, ".build") CFLAGS = ["-O2", "-std=c17", "-fno-lto", "-g"] + (extra_cflags or []) ap = argparse.ArgumentParser() ap.add_argument("--seed", type=int, default=None) ap.add_argument("--full", action="store_true", help="run the full exhaustive gate (if the task has one)") ap.add_argument("--quiet", action="store_true") args = ap.parse_args() seed = args.seed if args.seed is not None else int(time.time()) % 100000 os.makedirs(BUILD, exist_ok=True) sub_srcs = sorted(glob.glob(os.path.join(SUB, "*.c"))) if not sub_srcs: sys.exit("no .c files in submission/") t0 = time.time() ref = os.path.join(VER, "reference.c") refs = [ref] if os.path.exists(ref) else [] sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs, *refs, os.path.join(VER, "verify.c"), "-o", os.path.join(BUILD, "verify"), "-lm", "-lpthread"]) sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs, os.path.join(VER, "runner.c"), "-o", os.path.join(BUILD, "runner"), "-lm"]) if not os.path.exists(os.path.join(BUILD, "runner_given")): sh(["cc", *CFLAGS, "-DRUNNER_GIVEN", os.path.join(VER, "given.c"), os.path.join(VER, "runner.c"), "-o", os.path.join(BUILD, "runner_given"), "-lm"]) t_build = time.time() - t0 t0 = time.time() vargs = [str(seed)] + (["--full"] if args.full else []) + (verify_args or []) r = subprocess.run([os.path.join(BUILD, "verify"), *vargs], capture_output=True, text=True) if r.returncode != 0: print(r.stdout, end="") print(r.stderr, end="", file=sys.stderr) print("grade: FAIL (verification)") sys.exit(1) t_verify = time.time() - t0 def measure(binary, func): corpus = os.path.join(BUILD, f"corpus_{seed}.bin") if not os.path.exists(corpus): sh(["python3", os.path.join(VER, "gen_corpus.py"), str(seed), corpus]) cg = os.path.join(BUILD, f"callgrind.{binary}.out") if os.path.exists(cg): os.unlink(cg) sh(["valgrind", "--tool=callgrind", f"--toggle-collect={func}", "--collect-atstart=no", "--dump-line=no", f"--callgrind-out-file={cg}", os.path.join(BUILD, binary), corpus]) total = 0 with open(cg) as f: for line in f: ls = line.strip() if re.match(r"^\d+ \d+$", ls) or re.match(r"^\d+ \d+ ", ls): total += int(ls.split()[1]) if total == 0: sys.exit(f"cost extraction failed (did you rename {func}?)") return total t0 = time.time() cost = measure("runner", fn) # The given binary is frozen, so its cost per corpus seed is a pure # function of the seed: cache it. gcache = os.path.join(BUILD, f"given_cost_{seed}.json") if os.path.exists(gcache): with open(gcache) as f: given = json.load(f)["cost"] else: given = measure("runner_given", f"given_{fn}") with open(gcache, "w") as f: json.dump({"cost": given}, f) t_measure = time.time() - t0 score = math.log2(given / cost) rec = {"ts": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()), "seed": seed, "cost": cost, "given_cost": given, "score": round(score, 4), "full_gate": bool(args.full)} with open(os.path.join(here, "scores.jsonl"), "a") as f: f.write(json.dumps(rec) + "\n") if not args.quiet: print(f"build {t_build:5.1f}s") print(f"verify {t_verify:5.1f}s PASS{' (FULL gate)' if args.full else ''}") print(f"measure {t_measure:5.1f}s {cost:,} instructions (given: {given:,})") print(f"SCORE {score:+.4f} ({given / cost:.3f}x)") --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat verify/runner.c"}

// runner.c — cost-measurement driver for json-unescape. // Reads the corpus (len-prefixed records), calls json_unescape on each. // Run under callgrind; the grader extracts instructions attributed to // json_unescape and callees via --toggle-collect. #include <stdint.h> #include <stddef.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #ifdef RUNNER_GIVEN size_t given_json_unescape(const uint8_t *in, size_t in_len, uint8_t *out); #define json_unescape given_json_unescape #else size_t json_unescape(const uint8_t *in, size_t in_len, 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 * (1 << 20) + 64); // >= 3*maxrec+4 unsigned long long checksum = 0, total_in = 0, n_rec = 0; // Warmup pass (not measured; callgrind collection toggles on json_unescape, // but the first pass also faults in pages so counts are pure). // Measured work: one pass over all records. size_t off = 0; while (off + 4 <= (size_t)sz) { uint32_t len; memcpy(&len, data + off, 4); off += 4; if (off + len > (size_t)sz) { fprintf(stderr, "corrupt corpus\n"); return 2; } size_t r = json_unescape(data + off, len, out); if (r == (size_t)-1) { fprintf(stderr, "BUG: corpus record rejected (record %llu)\n", n_rec); return 3; } // fold output into checksum so the call cannot be optimized away for (size_t k = 0; k < r; k += 64) checksum += out[k]; checksum += r; total_in += len; n_rec++; off += len; } printf("runner: %llu records, %llu input bytes, checksum %llu\n", n_rec, total_in, checksum); return 0; } --- Command finished with exit code: 0 ---

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "content": "// solve.c \u2014 optimized json_unescape.\n//\n// Strategy: the character classes that require special handling\n// (control bytes 0x00-0x1F, '\"' = 0x22, '\\\\' = 0x5C) are ALL < 0x80.\n// Every byte with the high bit set (0x80-0xFF) is unconditionally plain\n// passthrough. That lets us scan 8 bytes at a time with SWAR bit tricks\n// (Alan Mycroft's haszero/hasless) to find the next byte that needs\n// attention, and bulk-memcpy everything before it. This turns the\n// dominant \"plain run\" regimes (~65% of the corpus by weight) from a\n// byte-at-a-time table lookup loop into an 8-bytes-per-iteration scan.\n//\n// The escape decode path is also tightened: hex nibble decode is\n// branch-free (table lookup + OR-of-sentinels validity check).\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n// -1 for non-hex-digit bytes, else the nibble value 0-15.\nstatic const int8_t HEXVAL[256] = {\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n};\n\nstatic inline uint64_t load64(const uint8_t *p) {\n uint64_t v;\n memcpy(&v, p, 8);\n return v;\n}\n\n// Bit tricks operate on the assumption every byte lane holds a value in\n// 0..255; they are the classic \"Bit Twiddling Hacks\" SWAR idioms.\nstatic inline uint64_t haszero(uint64_t v) {\n return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL;\n}\nstatic inline uint64_t hasvalue(uint64_t x, uint8_t n) {\n return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n));\n}\nstatic inline uint64_t hasless(uint64_t x, uint8_t n) {\n return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL;\n}\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}\n\nsize_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) {\n size_t i = 0, o = 0;\n while (i < in_len) {\n size_t start = i;\n\n // Bulk-scan 8 bytes at a time for a run of plain passthrough bytes.\n // Any byte needing special handling (control char, '\"', '\\\\') has\n // its high bit clear, so this test is exact.\n while (i + 8 <= in_len) {\n uint64_t w = load64(in + i);\n uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C);\n if (special) break;\n i += 8;\n }\n // Scalar cleanup: finishes the last (<8-byte) tail, and/or pins\n // down the exact byte inside a chunk that tripped the fast test.\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n i++;\n }\n\n if (i > start) {\n memcpy(out + o, in + start, i - start);\n o += i - start;\n }\n if (i >= in_len) break;\n\n uint8_t c = in[i];\n if (c != 0x5C) return I ... [2172 characters truncated for page size]

Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c (148 lines): 1- // solve.c — the given implementation of json_unescape. 2- // This is your starting point: a clean, production-quality scalar 3- // implementation of the kind found in mainstream JSON parsers. 4- // Make it faster. See ../spec.md for the contract. Grade with ../grade. 1+ // solve.c — optimized json_unescape. 2+ // 3+ // Strategy: the character classes that require special handling 4+ // (control bytes 0x00-0x1F, '"' = 0x22, '\\' = 0x5C) are ALL < 0x80. 5+ // Every byte with the high bit set (0x80-0xFF) is unconditionally plain 6+ // passthrough. That lets us scan 8 bytes at a time with SWAR bit tricks 7+ // (Alan Mycroft's haszero/hasless) to find the next byte that needs 8+ // attention, and bulk-memcpy everything before it. This turns the 9+ // dominant "plain run" regimes (~65% of the corpus by weight) from a 10+ // byte-at-a-time table lookup loop into an 8-bytes-per-iteration scan. 11+ // 12+ // The escape decode path is also tightened: hex nibble decode is 13+ // branch-free (table lookup + OR-of-sentinels validity check). 11- // Character class table: 0 = plain passthrough, 1 = backslash, 2 = invalid. 12- static const uint8_t CLASS[256] = { 13- 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0x00-0x0F ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -20"}

build 0.6s verify 0.8s PASS measure 1.2s 44,910,993 instructions (given: 53,122,064) SCORE +0.2422 (1.183x) --- Command finished with exit code: 0 ---

{"command": "cc --version; uname -m; gcc -march=native -dM -E - < /dev/null | grep -i avx | head; gcc -march=native -dM -E - < /dev/null | grep -i sse2"}

cc (GCC) 16.1.1 20260625 Copyright (C) 2026 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. x86_64 #define __AVX512F__ 1 #define __AVX512BITALG__ 1 #define __AVX512VBMI2__ 1 #define __AVX512VBMI__ 1 #define __AVX512IFMA__ 1 #define __AVX512BW__ 1 #define __AVX__ 1 #define __AVX512VL__ 1 #define __AVX512CD__ 1 #define __AVX512VPOPCNTDQ__ 1 #define __SSE2_MATH__ 1 #define __SSE2__ 1 --- Command finished with exit code: 0 ---

{"command": "valgrind --version"}

valgrind-3.25.1 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/t.c << 'EOF'\n#pragma GCC target(\"avx2\")\n#include <immintrin.h>\nint test(const char*p){\n __m256i v = _mm256_loadu_si256((const __m256i*)p);\n __m256i lt = _mm256_cmpgt_epi8(_mm256_set1_epi8(0x20), v);\n return _mm256_movemask_epi8(lt);\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g -c /tmp/t.c -o /tmp/t.o && echo OK"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/t2.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n__attribute__((target(\"avx2\")))\nint test(const char*p){\n __m256i v = _mm256_loadu_si256((const __m256i*)p);\n __m256i lt = _mm256_cmpgt_epi8(_mm256_set1_epi8(0x20), v);\n return _mm256_movemask_epi8(lt);\n}\nint main(){\n char buf[32];\n for(int i=0;i<32;i++) buf[i]='a';\n buf[5]=1;\n printf(\"%d\\n\", test(buf));\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t2.c -o /tmp/t2 && /tmp/t2\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/t2 2>&1 | tail -5"}

32 ==333== ==333== Events : Ir ==333== Collected : 127819 ==333== ==333== I refs: 127,819 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t3.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <string.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nint test(const char*p){\n __m256i v = _mm256_loadu_si256((const __m256i*)p);\n __mmask32 lt = _mm256_cmplt_epi8_mask(v, _mm256_set1_epi8(0x20));\n return lt;\n}\nint main(){\n char buf[32];\n for(int i=0;i<32;i++) buf[i]='a';\n buf[5]=1;\n printf(\"%d\\n\", test(buf));\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t3.c -o /tmp/t3 && /tmp/t3\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/t3 2>&1 | tail -5"}

32 ==356== ==356== Events : Ir ==356== Collected : 124005 ==356== ==356== I refs: 124,005 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t4.c << 'EOF'\n#include <stdio.h>\nint main(){\n __builtin_cpu_init();\n printf(\"avx2=%d avx512f=%d avx512bw=%d avx512vl=%d\\n\",\n __builtin_cpu_supports(\"avx2\"),\n __builtin_cpu_supports(\"avx512f\"),\n __builtin_cpu_supports(\"avx512bw\"),\n __builtin_cpu_supports(\"avx512vl\"));\n}\nEOF\ngcc -O2 /tmp/t4.c -o /tmp/t4 && /tmp/t4"}

avx2=1024 avx512f=32768 avx512bw=2097152 avx512vl=1048576 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && sed -n '1,60p' verify/verify.c"}

// verify.c — exhaustive correctness gate for json-unescape. // Compares json_unescape (submission) against ref_json_unescape (oracle) on: // 1. every string of length 0..MAXL over a 19-byte adversarial alphabet // 2. all 65536 \uXXXX forms // 3. all 1048576 surrogate pair combinations // 4. the above with prefix/suffix padding // 5. 100000 seeded random long strings across regimes // Exit 0 = pass. Any mismatch prints the counterexample and exits 1. #include <stdint.h> #include <stddef.h> #include <stdio.h> #include <stdlib.h> #include <string.h> size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out); size_t ref_json_unescape(const uint8_t *in, size_t in_len, uint8_t *out); #define INVALID ((size_t)-1) static uint8_t buf_sub[1 << 16]; static uint8_t buf_ref[1 << 16]; static unsigned long long n_cases = 0; static void dump_hex(const uint8_t *p, size_t n) { for (size_t i = 0; i < n; i++) fprintf(stderr, "%02x ", p[i]); fprintf(stderr, "\n"); } static void check(const uint8_t *in, size_t in_len) { // Poison output buffers so "forgot to write" mismatches are caught. memset(buf_sub, 0xAA, in_len * 3 + 8); memset(buf_ref, 0x55, in_len * 3 + 8); size_t r_sub = json_unescape(in, in_len, buf_sub); size_t r_ref = ref_json_unescape(in, in_len, buf_ref); n_cases++; if (r_sub != r_ref || (r_ref != INVALID && memcmp(buf_sub, buf_ref, r_ref) != 0)) { fprintf(stderr, "MISMATCH on input (%zu bytes): ", in_len); dump_hex(in, in_len); if (r_ref == INVALID) fprintf(stderr, " expected: INVALID\n"); else { fprintf(stderr, " expected (%zu bytes): ", r_ref); dump_hex(buf_ref, r_ref); } if (r_sub == INVALID) fprintf(stderr, " got: INVALID\n"); else { fprintf(stderr, " got (%zu bytes): ", r_sub); dump_hex(buf_sub, r_sub); } exit(1); } } // ---- 1. exhaustive short strings over adversarial alphabet ---- // Covers: every escape kind, truncated escapes, invalid escapes, hex digit // boundaries (0/9/a/f/A/F and non-hex), surrogate lead bytes via u d 8-9 a-c, // control byte, '"', high byte. static const uint8_t ALPHA[] = { --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t5.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nint test(const char*p){\n __m512i v = _mm512_loadu_si512((const void*)p);\n __mmask64 lt = _mm512_cmplt_epi8_mask(v, _mm512_set1_epi8(0x20));\n return (int)lt;\n}\nint main(){\n char buf[64];\n for(int i=0;i<64;i++) buf[i]='a';\n buf[5]=1;\n printf(\"%d\\n\", test(buf));\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t5.c -o /tmp/t5 && /tmp/t5\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/t5 2>&1 | tail -5"}

32 ==411== ==411== Events : Ir ==411== Collected : 123991 ==411== ==411== I refs: 123,991 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t6.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <string.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic inline uint64_t special_mask(const unsigned char *p) {\n __m512i v = _mm512_loadu_si512((const void*)p);\n __mmask64 lt = _mm512_cmplt_epi8_mask(v, _mm512_set1_epi8(0x20));\n __mmask64 q = _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x22));\n __mmask64 bs = _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x5C));\n return (uint64_t)(lt | q | bs);\n}\nint main(){\n unsigned char buf[64];\n memset(buf,'a',64);\n buf[40]=1;\n uint64_t m = special_mask(buf);\n printf(\"%llu tz=%d\\n\",(unsigned long long)m, __builtin_ctzll(m));\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t6.c -o /tmp/t6 && /tmp/t6"}

/tmp/t6.c:5:15: error: unknown type name ‘uint64_t’ 5 | static inline uint64_t special_mask(const unsigned char *p) { | ^~~~~~~~ /tmp/t6.c:4:1: note: ‘uint64_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’ 3 | #include <string.h> +++ |+#include <stdint.h> 4 | __attribute__((target("avx512f,avx512bw,avx512vl"))) /tmp/t6.c: In function ‘special_mask’: /tmp/t6.c:10:11: error: ‘uint64_t’ undeclared (first use in this function) 10 | return (uint64_t)(lt | q | bs); | ^~~~~~~~ /tmp/t6.c:10:11: note: ‘uint64_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’ /tmp/t6.c:10:11: note: each undeclared identifier is reported only once for each function it appears in /tmp/t6.c: In function ‘main’: /tmp/t6.c:16:3: error: unknown type name ‘uint64_t’ 16 | uint64_t m = special_mask(buf); | ^~~~~~~~ /tmp/t6.c:16:3: note: ‘uint64_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’ --- Command finished with exit code: 1 --- Exit code: 1

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && grep -n \"CFLAGS\" ../../harness/grade.py"}

23: CFLAGS = ["-O2", "-std=c17", "-fno-lto", "-g"] + (extra_cflags or []) 41: sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs, *refs, 44: sh(["cc", *CFLAGS, "-I", SUB, *sub_srcs, 47: sh(["cc", *CFLAGS, "-DRUNNER_GIVEN", --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t7.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic void scan(const unsigned char *in, size_t len) {\n size_t i=0;\n while (i+64<=len) {\n __m512i v = _mm512_loadu_si512((const void*)(in+i));\n __mmask64 special = _mm512_cmplt_epi8_mask(v, _mm512_set1_epi8(0x20))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x22))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x5C));\n if (special) { i += __builtin_ctzll(special); break; }\n i += 64;\n }\n printf(\"i=%zu\\n\", i);\n}\nint main(){\n unsigned char buf[128];\n memset(buf,'a',128);\n buf[70]=1;\n scan(buf,128);\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t7.c -o /tmp/t7 && /tmp/t7"}

i=70 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/t8.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n// check masked memcpy approach: use _mm512_mask_compressstoreu or just plain copy full 64 bytes then adjust o\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic void copy_test(unsigned char *dst, const unsigned char *src, size_t n){\n size_t i=0;\n for(; i+64<=n; i+=64){\n __m512i v = _mm512_loadu_si512((const void*)(src+i));\n _mm512_storeu_si512((void*)(dst+i), v);\n }\n for(;i<n;i++) dst[i]=src[i];\n}\nint main(){\n unsigned char a[200], b[200];\n for(int i=0;i<200;i++) a[i]=i;\n copy_test(b,a,137);\n printf(\"%d\\n\", memcmp(a,b,137));\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t8.c -o /tmp/t8 && /tmp/t8"}

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

{"command": "cat > /tmp/t9.c << 'EOF'\n#include <stdio.h>\nstatic int fast(void){ return 42; }\nstatic int slow(void){ return 1; }\nstatic void *resolve(void) { return __builtin_cpu_supports(\"avx2\") ? (void*)fast : (void*)slow; }\nint myfunc(void) __attribute__((ifunc(\"resolve\")));\nint main(){ printf(\"%d\\n\", myfunc()); }\nEOF\ngcc -O2 /tmp/t9.c -o /tmp/t9 && /tmp/t9"}

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

{"command": "cat > /tmp/t10.c << 'EOF'\n#include <stdio.h>\n#include <stdint.h>\nstatic void ctor_test(void) __attribute__((constructor));\nstatic int chosen = -1;\nstatic void ctor_test(void) {\n chosen = __builtin_cpu_supports(\"avx512f\") ? 2 : (__builtin_cpu_supports(\"avx2\") ? 1 : 0);\n}\nint main(){ printf(\"%d\\n\", chosen); }\nEOF\ngcc -O2 /tmp/t10.c -o /tmp/t10 && /tmp/t10"}

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

{"command": "cat > /tmp/t11.c << 'EOF'\n#include <immintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic void maskstore_test(unsigned char *dst, const unsigned char *src, int p){\n __m512i v = _mm512_loadu_si512((const void*)src);\n __mmask64 m = (p==64)? ~0ULL : ((1ULL<<p)-1);\n _mm512_mask_storeu_epi8((void*)dst, m, v);\n}\nint main(){\n unsigned char src[64], dst[64];\n for(int i=0;i<64;i++){src[i]=i+1; dst[i]=0xAA;}\n maskstore_test(dst,src,13);\n for(int i=0;i<20;i++) printf(\"%d \", dst[i]);\n printf(\"\\n\");\n}\nEOF\ngcc -O2 -std=c17 -fno-lto -g /tmp/t11.c -o /tmp/t11 && /tmp/t11"}

1 2 3 4 5 6 7 8 9 10 11 12 13 170 170 170 170 170 170 170 --- Command finished with exit code: 0 ---

{"content": "// solve.c \u2014 optimized json_unescape.\n//\n// The three \"special\" byte classes (control 0x00-0x1F, '\"'=0x22, '\\\\'=0x5C)\n// are all < 0x80, so every high-bit-set byte is unconditionally plain\n// passthrough. We exploit that with a vectorized scan that finds runs of\n// plain bytes and copies them directly, falling back to a scalar escape\n// decoder only when a backslash/quote/control byte is actually hit.\n//\n// Two scan implementations are provided:\n// - AVX-512 (64 bytes/iteration), used when the CPU supports it.\n// - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless), used\n// otherwise.\n// The choice is made once via ifunc/constructor-style dispatch; per the\n// grading rules, one-time setup (including CPU feature detection) is not\n// counted, only per-call work.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n// -1 for non-hex-digit bytes, else the nibble value 0-15.\nstatic const int8_t HEXVAL[256] = {\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n};\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}\n\n// Finds i = the index of the first \"special\" byte (< 0x20, '\"', or '\\\\')\n// at or after `i`, scanning up to `in_len`. Never reads past `in_len`.\n// Returns the new i (== in_len if none found in range, though callers\n// only rely on it being an exact stopping point, not that it reaches len).\ntypedef size_t (*scan_fn)(const uint8_t *in, size_t i, size_t in_len);\n\nstatic size_t scan_plain_scalar(const uint8_t *in, size_t i, size_t in_len) {\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n i++;\n }\n return i;\n}\n\nstatic inline uint64_t load64(const uint8_t *p) {\n uint64_t v;\n memcpy(&v, p, 8);\n return v;\n}\nstatic inline uint64_t haszero(uint64_t v) {\n return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL;\n}\nstatic inline uint64_t hasvalue(uint64_t x, uint8_t n) {\n return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n));\n}\nstatic inline uint64_t hasless(uint64_t x, uint8_t n) {\n return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL;\n}\n\nstatic size_t scan_plain_swar(const uint8_t *in, size_t i, size_t in_len) {\n while (i + 8 <= in_len) {\n uint64_t w = load64(in + i);\n uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C);\n if (special) {\n // Locate exact byte within this 8-byte lane.\n int bit = __builtin_ctzll(special);\n return i + (size_t)(bit >> 3);\n }\n i += 8;\n }\n return scan_plain_scalar(in, i, in_len);\n}\n\n#if defined(__x86_64__) || defined(__i386__)\n#include <immintrin.h>\n\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic size_t scan_plain_avx512(const uint8_t *in, size_t i, size_t in_len) {\n __m512i lo = _mm512_s ... [4931 characters truncated for page size]

Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c (226 lines): 3- // Strategy: the character classes that require special handling 4- // (control bytes 0x00-0x1F, '"' = 0x22, '\\' = 0x5C) are ALL < 0x80. 5- // Every byte with the high bit set (0x80-0xFF) is unconditionally plain 6- // passthrough. That lets us scan 8 bytes at a time with SWAR bit tricks 7- // (Alan Mycroft's haszero/hasless) to find the next byte that needs 8- // attention, and bulk-memcpy everything before it. This turns the 9- // dominant "plain run" regimes (~65% of the corpus by weight) from a 10- // byte-at-a-time table lookup loop into an 8-bytes-per-iteration scan. 3+ // The three "special" byte classes (control 0x00-0x1F, '"'=0x22, '\\'=0x5C) 4+ // are all < 0x80, so every high-bit-set byte is unconditionally plain 5+ // passthrough. We exploit that with a vectorized scan that finds runs of 6+ // plain bytes and copies them directly, falling back to a scalar escape 7+ // decoder only when a backslash/quote/control byte is actually hit. 12- // The escape decode path is also tightened: hex nibble decode is 13- // branch-free (table lookup + OR-of-sentinels validity check). 9+ // Two scan implementations are provided: 10+ // - AVX-512 (64 bytes/iteration), used when the CPU supports it. 11+ // - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless), used 12+ // otherwise. 13+ // The choice is made once via ifunc/constructor-style dispatch; per the ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -30"}

build 1.4s verify 0.8s PASS measure 1.2s 29,224,308 instructions (given: 51,909,284) SCORE +0.8288 (1.776x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat .build/runner.c 2>/dev/null; ls .build"}

callgrind.runner.out callgrind.runner_given.out corpus_28567.bin corpus_28588.bin corpus_28872.bin corpus_29240.bin given_cost_28567.json given_cost_28588.json given_cost_28872.json given_cost_29240.json runner runner_given verify --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out 2>/dev/null | head -60"}

-------------------------------------------------------------------------------- Profile data file '.build/callgrind.runner.out' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 1181934 Trigger: Program termination Profiled target: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/corpus_29240.bin (PID 571, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 5,521,512 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 3,403,265 (61.64%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 961,273 (17.41%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_plain_avx2 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 596,332 (10.80%) submission/solve.c:scan_plain_avx2 413,341 ( 7.49%) /usr/src/debug/glibc/glibc/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:__memcpy_avx_unaligned_erms [/usr/lib/libc.so.6] 84,103 ( 1.52%) submission/solve.c:scan_plain_swar [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 62,287 ( 1.13%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:scan_plain_avx2 -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h -------------------------------------------------------------------------------- Ir -- line 865 ---------------------------------------- . _mm256_store_si256 (__m256i *__P, __m256i __A) . { . *__P = __A; . } . . extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_loadu_si256 (__m256i_u const *__P) . { 62,287 ( 1.13%) return *__P; . } . . extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_storeu_si256 (__m256i_u *__P, __m256i __A) . { . *__P = __A; . } . -- line 881 ---------------------------------------- -------------------------------------------------------------------------------- -- Auto-annotated source: submission/solve.c -------------------------------------------------------------------------------- --- Command finished with exit code: 0 ---

{"command": "cat /proc/cpuinfo | grep flags | head -1 | tr ' ' '\\n' | grep avx\necho ---\nvalgrind --tool=callgrind echo test 2>&1 | head -5\ncat > /tmp/cpucheck.c << 'EOF'\n#include <stdio.h>\nint main(){\n __builtin_cpu_init();\n printf(\"avx512f=%d avx512bw=%d avx512vl=%d avx2=%d\\n\",\n __builtin_cpu_supports(\"avx512f\"),\n __builtin_cpu_supports(\"avx512bw\"),\n __builtin_cpu_supports(\"avx512vl\"),\n __builtin_cpu_supports(\"avx2\"));\n}\nEOF\ngcc -O2 /tmp/cpucheck.c -o /tmp/cpucheck\n/tmp/cpucheck\nvalgrind --tool=callgrind /tmp/cpucheck 2>&1 | tail -5"}

avx avx2 avx512f avx512dq avx512cd avx512bw avx512vl avx512vbmi avx512_vbmi2 avx512_vnni avx512_bitalg avx512_vpopcntdq --- ==624== Callgrind, a call-graph generating cache profiler ==624== Copyright (C) 2002-2017, and GNU GPL'd, by Josef Weidendorfer et al. ==624== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info ==624== Command: echo test ==624== avx512f=32768 avx512bw=2097152 avx512vl=1048576 avx2=1024 ==633== ==633== Events : Ir ==633== Collected : 129012 ==633== ==633== I refs: 129,012 --- Command finished with exit code: 0 ---

{"command": "valgrind /tmp/cpucheck 2>&1 | tail -5"}

==652== ==652== All heap blocks were freed -- no leaks are possible ==652== ==652== For lists of detected and suppressed errors, rerun with: -s ==652== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner | grep -A2 \"select_scan_impl>:\" "}

0000000000001140 <select_scan_impl>: 1140: 48 83 ec 08 sub $0x8,%rsp 1144: e8 97 02 00 00 call 13e0 <__cpu_indicator_init> --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --collect-atstart=no --toggle-collect=main /tmp/cpucheck 2>&1 | grep -E \"avx|Ir\""}

avx512f=0 avx512bw=0 avx512vl=0 avx2=1024 ==685== Events : Ir --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out 2>/dev/null | grep -i avx512"}

. __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_plain_avx512(const uint8_t *in, size_t i, size_t in_len) { --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/force512.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <string.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nstatic size_t scan(const unsigned char *in, size_t i, size_t n) {\n while (i + 64 <= n) {\n __m512i v = _mm512_loadu_si512((const void*)(in+i));\n __mmask64 special = _mm512_cmplt_epu8_mask(v, _mm512_set1_epi8(0x20))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x22))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x5C));\n if (special) return i + __builtin_ctzll(special);\n i += 64;\n }\n return n;\n}\nint main(){\n unsigned char buf[128];\n memset(buf,'a',128);\n buf[70]=1;\n printf(\"%zu\\n\", scan(buf,0,128));\n}\nEOF\ngcc -O2 -std=c17 /tmp/force512.c -o /tmp/force512 && /tmp/force512\nvalgrind /tmp/force512 2>&1 | tail -8"}

70 ==723== HEAP SUMMARY: ==723== in use at exit: 0 bytes in 0 blocks ==723== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==723== ==723== All heap blocks were freed -- no leaks are possible ==723== ==723== For lists of detected and suppressed errors, rerun with: -s ==723== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --collect-atstart=yes /tmp/cpucheck 2>&1 | grep avx"}

avx512f=0 avx512bw=0 avx512vl=0 avx2=1024 --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind /tmp/cpucheck 2>&1 | grep avx\n# check further: is avx512 ever true under callgrind on this valgrind version?\nvalgrind --tool=none /tmp/cpucheck 2>&1 | grep avx"}

avx512f=0 avx512bw=0 avx512vl=0 avx2=1024 avx512f=0 avx512bw=0 avx512vl=0 avx2=1024 --- Command finished with exit code: 0 ---

{"command": "/tmp/cpucheck\necho \"---\"\ncat /proc/cpuinfo | grep -o 'avx512[a-z_]*' | sort -u"}

avx512f=32768 avx512bw=2097152 avx512vl=1048576 avx2=1024 --- avx512_bitalg avx512_vbmi avx512_vnni avx512_vpopcntdq avx512bw avx512cd avx512dq avx512f avx512vbmi avx512vl --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '1,200p'"}

-------------------------------------------------------------------------------- Profile data file '.build/callgrind.runner.out' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 1181934 Trigger: Program termination Profiled target: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/corpus_29240.bin (PID 571, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: submission/solve.c Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 5,521,512 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 3,403,265 (61.64%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 961,273 (17.41%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_plain_avx2 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 596,332 (10.80%) submission/solve.c:scan_plain_avx2 413,341 ( 7.49%) /usr/src/debug/glibc/glibc/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:__memcpy_avx_unaligned_erms [/usr/lib/libc.so.6] 84,103 ( 1.52%) submission/solve.c:scan_plain_swar [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 62,287 ( 1.13%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:scan_plain_avx2 -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h -------------------------------------------------------------------------------- Ir -- line 225 ---------------------------------------- . ((__m256i) __builtin_ia32_pblendw256 ((__v16hi)(__m256i)(X), \ . (__v16hi)(__m256i)(Y), (int)(M))) . #endif . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi8 (__m256i __A, __m256i __B) . { 387,206 ( 7.01%) return (__m256i) ((__v32qi)__A == (__v32qi)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A == (__v16hi)__B); . } -- line 241 ---------------------------------------- -- line 253 ---------------------------------------- . { . return (__m256i) ((__v4di)__A == (__v4di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi8 (__m256i __A, __m256i __B) . { 193,603 ( 3.51%) return (__m256i) ((__v32qs)__A > (__v32qs)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A > (__v16hi)__B); . } -- line 269 ---------------------------------------- -- line 427 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pminud256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline int . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_movemask_epi8 (__m256i __A) . { 62,287 ( 1.13%) return __builtin_ia32_pmovmskb256 ((__v32qi)__A); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cvtepi8_epi16 (__m128i __X) . { . return (__m256i) __builtin_ia32_pmovsxbw256 ((__v16qi)__X); . } -- line 443 ---------------------------------------- -- line 568 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pmuludq256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_or_si256 (__m256i __A, __m256i __B) . { 124,574 ( 2.26%) return (__m256i) ((__v4du)__A | (__v4du)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sad_epu8 (__m256i __A, __m256i __B) . { . return (__m256i)__builtin_ia32_psadbw256 ((__v32qi)__A, (__v32qi)__B); . } -- line 584 ---------------------------------------- -- line 795 ---------------------------------------- . { . return (__m256i)__builtin_ia32_psrlq256((__v4di)__A, (__v2di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi8 (__m256i __A, __m256i __B) . { 193,603 ( 3.51%) return (__m256i) ((__v32qu)__A - (__v32qu)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hu)__A - (__v16hu)__B); . } -- line 811 ---------------------------------------- -------------------------------------------------------------------------------- -- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 35 ---------------------------------------- . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { 367,960 ( 6.66%) int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 190,270 ( 3.45%) if ((h0 | h1 | h2 | h3) < 0) return -1; 260,088 ( 4.71%) *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); . return 0; . } . . // Finds i = the index of the first "special" byte (< 0x20, '"', or '\\') . // at or after `i`, scanning up to `in_len`. Never reads past `in_len`. . // Returns the new i (== in_len if none found in range, though callers . // only rely on it being an exact stopping point, not that it reaches len). . typedef size_t (*scan_fn)(const uint8_t *in, size_t i, size_t in_len); . . static size_t scan_plain_scalar(const uint8_t *in, size_t i, size_t in_len) { 4,066 ( 0.07%) while (i < in_len) { 1,628 ( 0.03%) uint8_t c = in[i]; 9,768 ( 0.18%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 1,529 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,317 ( 0.02%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 14,286 ( 0.26%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,768 ( 0.14%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,201 ( 0.09%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 11,250 ( 0.20%) static size_t scan_plain_swar(const uint8_t *in, size_t i, size_t in_len) { 8,534 ( 0.15%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,884 ( 0.07%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,634 ( 0.05%) if (special) { . // Locate exact byte within this 8-byte lane. 746 ( 0.01%) int bit = __builtin_ctzll(special); 1,492 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_plain_scalar(in, i, in_len); 10,000 ( 0.18%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '200,400p'"}

. } . // Emit UTF-8. 50,948 ( 0.92%) if (cp < 0x80) { 201 ( 0.00%) out[o++] = (uint8_t)cp; 50,814 ( 0.92%) } else if (cp < 0x800) { 52,306 ( 0.95%) out[o++] = (uint8_t)(0xC0 | (cp >> 6)); 29,137 ( 0.53%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 49,322 ( 0.89%) } else if (cp < 0x10000) { 73,983 ( 1.34%) out[o++] = (uint8_t)(0xE0 | (cp >> 12)); . out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 123,305 ( 2.23%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } else { 25,160 ( 0.46%) out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 56,857 ( 1.03%) out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 111,723 ( 2.02%) out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 31,450 ( 0.57%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } . } 3,000 ( 0.05%) return o; 2,400 ( 0.04%) } -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h -------------------------------------------------------------------------------- Ir -- line 225 ---------------------------------------- . ((__m256i) __builtin_ia32_pblendw256 ((__v16hi)(__m256i)(X), \ . (__v16hi)(__m256i)(Y), (int)(M))) . #endif . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi8 (__m256i __A, __m256i __B) . { 387,206 ( 7.01%) return (__m256i) ((__v32qi)__A == (__v32qi)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A == (__v16hi)__B); . } -- line 241 ---------------------------------------- -- line 253 ---------------------------------------- . { . return (__m256i) ((__v4di)__A == (__v4di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi8 (__m256i __A, __m256i __B) . { 193,603 ( 3.51%) return (__m256i) ((__v32qs)__A > (__v32qs)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A > (__v16hi)__B); . } -- line 269 ---------------------------------------- -- line 427 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pminud256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline int . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_movemask_epi8 (__m256i __A) . { 62,287 ( 1.13%) return __builtin_ia32_pmovmskb256 ((__v32qi)__A); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cvtepi8_epi16 (__m128i __X) . { . return (__m256i) __builtin_ia32_pmovsxbw256 ((__v16qi)__X); . } -- line 443 ---------------------------------------- -- line 568 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pmuludq256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_or_si256 (__m256i __A, __m256i __B) . { 124,574 ( 2.26%) return (__m256i) ((__v4du)__A | (__v4du)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sad_epu8 (__m256i __A, __m256i __B) . { . return (__m256i)__builtin_ia32_psadbw256 ((__v32qi)__A, (__v32qi)__B); . } -- line 584 ---------------------------------------- -- line 795 ---------------------------------------- . { . return (__m256i)__builtin_ia32_psrlq256((__v4di)__A, (__v2di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi8 (__m256i __A, __m256i __B) . { 193,603 ( 3.51%) return (__m256i) ((__v32qu)__A - (__v32qu)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hu)__A - (__v16hu)__B); . } -- line 811 ---------------------------------------- -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h -------------------------------------------------------------------------------- Ir -- line 865 ---------------------------------------- . _mm256_store_si256 (__m256i *__P, __m256i __A) . { . *__P = __A; . } . . extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_loadu_si256 (__m256i_u const *__P) . { 62,287 ( 1.13%) return *__P; . } . . extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_storeu_si256 (__m256i_u *__P, __m256i __A) . { . *__P = __A; . } . -- line 881 ---------------------------------------- -------------------------------------------------------------------------------- The following files chosen for auto-annotation could not be found: -------------------------------------------------------------------------------- /usr/src/debug/glibc/glibc/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 5,107,260 (92.50%) events annotated --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '90,200p'"}

. { 193,603 ( 3.51%) return (__m256i) ((__v32qs)__A > (__v32qs)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A > (__v16hi)__B); . } -- line 269 ---------------------------------------- -- line 427 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pminud256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline int . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_movemask_epi8 (__m256i __A) . { 62,287 ( 1.13%) return __builtin_ia32_pmovmskb256 ((__v32qi)__A); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cvtepi8_epi16 (__m128i __X) . { . return (__m256i) __builtin_ia32_pmovsxbw256 ((__v16qi)__X); . } -- line 443 ---------------------------------------- -- line 568 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pmuludq256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_or_si256 (__m256i __A, __m256i __B) . { 124,574 ( 2.26%) return (__m256i) ((__v4du)__A | (__v4du)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sad_epu8 (__m256i __A, __m256i __B) . { . return (__m256i)__builtin_ia32_psadbw256 ((__v32qi)__A, (__v32qi)__B); . } -- line 584 ---------------------------------------- -- line 795 ---------------------------------------- . { . return (__m256i)__builtin_ia32_psrlq256((__v4di)__A, (__v2di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi8 (__m256i __A, __m256i __B) . { 193,603 ( 3.51%) return (__m256i) ((__v32qu)__A - (__v32qu)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hu)__A - (__v16hu)__B); . } -- line 811 ---------------------------------------- -------------------------------------------------------------------------------- -- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 35 ---------------------------------------- . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { 367,960 ( 6.66%) int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 190,270 ( 3.45%) if ((h0 | h1 | h2 | h3) < 0) return -1; 260,088 ( 4.71%) *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); . return 0; . } . . // Finds i = the index of the first "special" byte (< 0x20, '"', or '\\') . // at or after `i`, scanning up to `in_len`. Never reads past `in_len`. . // Returns the new i (== in_len if none found in range, though callers . // only rely on it being an exact stopping point, not that it reaches len). . typedef size_t (*scan_fn)(const uint8_t *in, size_t i, size_t in_len); . . static size_t scan_plain_scalar(const uint8_t *in, size_t i, size_t in_len) { 4,066 ( 0.07%) while (i < in_len) { 1,628 ( 0.03%) uint8_t c = in[i]; 9,768 ( 0.18%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 1,529 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,317 ( 0.02%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 14,286 ( 0.26%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner | grep -c \"call.*memcpy\"\nnm .build/runner | grep -i json_unescape"}

1 0000000000002ca0 T json_unescape --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/force512b.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <string.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nsize_t scan(const unsigned char *in, size_t i, size_t n) {\n while (i + 64 <= n) {\n __m512i v = _mm512_loadu_si512((const void*)(in+i));\n __mmask64 special = _mm512_cmplt_epu8_mask(v, _mm512_set1_epi8(0x20))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x22))\n | _mm512_cmpeq_epi8_mask(v, _mm512_set1_epi8(0x5C));\n if (special) return i + __builtin_ctzll(special);\n i += 64;\n }\n return n;\n}\nint main(){\n unsigned char buf[128];\n memset(buf,'a',128);\n buf[70]=1;\n printf(\"%zu\\n\", scan(buf,0,128));\n}\nEOF\ngcc -O2 -std=c17 /tmp/force512b.c -o /tmp/force512b\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/force512b 2>&1 | tail -10"}

==861== ==861== Process terminating with default action of signal 4 (SIGILL): dumping core ==861== Illegal opcode at address 0x400124B ==861== at 0x400124B: scan (in /tmp/force512b) ==861== by 0x40010E0: main (in /tmp/force512b) ==861== ==861== Events : Ir ==861== Collected : 124246 ==861== ==861== I refs: 124,246 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && .build/verify 42 2>&1 | tail -20"}

verify: PASS (4596952 cases) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=scan_plain_avx2 -M intel | head -60"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002b50 <scan_plain_avx2>: 2b50: b8 5c 5c 5c 5c mov eax,0x5c5c5c5c 2b55: c5 f9 6e f0 vmovd xmm6,eax 2b59: b8 22 22 22 22 mov eax,0x22222222 2b5e: c5 f9 6e e8 vmovd xmm5,eax 2b62: b8 80 80 80 80 mov eax,0x80808080 2b67: c4 e2 7d 58 f6 vpbroadcastd ymm6,xmm6 2b6c: c5 f9 6e e0 vmovd xmm4,eax 2b70: b8 a0 a0 a0 a0 mov eax,0xa0a0a0a0 2b75: c4 e2 7d 58 ed vpbroadcastd ymm5,xmm5 2b7a: c5 f9 6e d8 vmovd xmm3,eax 2b7e: c4 e2 7d 58 e4 vpbroadcastd ymm4,xmm4 2b83: c4 e2 7d 58 db vpbroadcastd ymm3,xmm3 2b88: eb 5c jmp 2be6 <scan_plain_avx2+0x96> 2b8a: 66 2e 0f 1f 84 00 00 cs nop WORD PTR [rax+rax*1+0x0] 2b91: 00 00 00 2b94: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2b9b: 00 00 00 00 2b9f: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2ba6: 00 00 00 00 2baa: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2bb1: 00 00 00 00 2bb5: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2bbc: 00 00 00 00 2bc0: c5 fe 6f 44 37 e0 vmovdqu ymm0,YMMWORD PTR [rdi+rsi*1-0x20] 2bc6: c5 fd 74 ce vpcmpeqb ymm1,ymm0,ymm6 2bca: c5 fd 74 d5 vpcmpeqb ymm2,ymm0,ymm5 2bce: c5 fd fc c4 vpaddb ymm0,ymm0,ymm4 2bd2: c5 e5 64 c0 vpcmpgtb ymm0,ymm3,ymm0 2bd6: c5 f5 eb ca vpor ymm1,ymm1,ymm2 2bda: c5 f5 eb c0 vpor ymm0,ymm1,ymm0 2bde: c5 fd d7 c0 vpmovmskb eax,ymm0 2be2: 85 c0 test eax,eax 2be4: 75 1a jne 2c00 <scan_plain_avx2+0xb0> 2be6: 48 89 f1 mov rcx,rsi 2be9: 48 83 c6 20 add rsi,0x20 2bed: 48 39 f2 cmp rdx,rsi 2bf0: 73 ce jae 2bc0 <scan_plain_avx2+0x70> 2bf2: 48 89 ce mov rsi,rcx 2bf5: c5 f8 77 vzeroupper 2bf8: e9 43 fe ff ff jmp 2a40 <scan_plain_swar> 2bfd: 0f 1f 00 nop DWORD PTR [rax] 2c00: f3 0f bc c0 tzcnt eax,eax 2c04: 48 01 c8 add rax,rcx 2c07: c5 f8 77 vzeroupper 2c0a: c3 ret Disassembly of section .fini: --- Command finished with exit code: 0 ---

{"command": "valgrind --help 2>&1 | grep -i avx\nvalgrind --tool=callgrind --help 2>&1 | grep -i avx"}

--- Command finished with exit code: 1 --- Exit code: 1

{"command": "cat > /tmp/avxtest.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n__attribute__((target(\"avx512f\")))\nint main(){\n __m512i v = _mm512_set1_epi32(5);\n int arr[16];\n _mm512_storeu_si512((void*)arr, v);\n printf(\"%d\\n\", arr[0]);\n}\nEOF\ngcc -O2 /tmp/avxtest.c -o /tmp/avxtest && /tmp/avxtest\nvalgrind /tmp/avxtest 2>&1 | tail -10"}

5 5 ==931== ==931== HEAP SUMMARY: ==931== in use at exit: 0 bytes in 0 blocks ==931== total heap usage: 1 allocs, 1 frees, 4,096 bytes allocated ==931== ==931== All heap blocks were freed -- no leaks are possible ==931== ==931== For lists of detected and suppressed errors, rerun with: -s ==931== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/avxtest2.c << 'EOF'\n#include <immintrin.h>\n#include <stdio.h>\n#include <string.h>\n__attribute__((target(\"avx512f,avx512bw,avx512vl\")))\nint main(){\n unsigned char buf[64];\n memset(buf, 'a', 64);\n buf[10] = 1;\n __m512i v = _mm512_loadu_si512((const void*)buf);\n __mmask64 m1 = _mm512_cmplt_epu8_mask(v, _mm512_set1_epi8(0x20));\n printf(\"m1=%llx\\n\", (unsigned long long)m1);\n}\nEOF\ngcc -O2 /tmp/avxtest2.c -o /tmp/avxtest2 && /tmp/avxtest2\nvalgrind /tmp/avxtest2 2>&1 | tail -10"}

m1=400 ==959== at 0x400107C: main (in /tmp/avxtest2) ==959== ==959== HEAP SUMMARY: ==959== in use at exit: 0 bytes in 0 blocks ==959== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==959== ==959== All heap blocks were freed -- no leaks are possible ==959== ==959== For lists of detected and suppressed errors, rerun with: -s ==959== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "valgrind /tmp/avxtest2 2>&1 | head -20"}

==977== Memcheck, a memory error detector ==977== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al. ==977== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info ==977== Command: /tmp/avxtest2 ==977== vex amd64->IR: unhandled instruction bytes: 0x62 0xF2 0x7D 0x48 0x7C 0xC0 0xB8 0x20 0x20 0x20 vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0 vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=NONE vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0 ==977== valgrind: Unrecognised instruction at address 0x400107c. ==977== at 0x400107C: main (in /tmp/avxtest2) ==977== Your program just tried to execute an instruction that Valgrind ==977== did not recognise. There are two possible reasons for this. ==977== 1. Your program has a bug and erroneously jumped to a non-code ==977== location. If you are running Memcheck and you just saw a ==977== warning about a bad jump, it's probably your program's fault. ==977== 2. The instruction is legitimate but Valgrind doesn't handle it, ==977== i.e. it's Valgrind's fault. If you think this is the case or ==977== you are not sure, please let us know and we'll try to fix it. ==977== Either way, Valgrind will now raise a SIGILL signal which will --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '145,205p'"}

. __m256i eqb = _mm256_cmpeq_epi8(v, bs); . __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); . unsigned mask = (unsigned)_mm256_movemask_epi8(special); 124,574 ( 2.26%) if (mask) { 127,566 ( 2.31%) return i + (size_t)__builtin_ctz(mask); . } . i += 32; . } 3,750 ( 0.07%) return scan_plain_swar(in, i, in_len); 84,103 ( 1.52%) => submission/solve.c:scan_plain_swar (1,250x) 42,522 ( 0.77%) } . #endif . . static scan_fn g_scan = scan_plain_swar; . . __attribute__((constructor)) . static void select_scan_impl(void) { . #if defined(__x86_64__) || defined(__i386__) . __builtin_cpu_init(); -- line 145 ---------------------------------------- -- line 151 ---------------------------------------- . if (__builtin_cpu_supports("avx2")) { . g_scan = scan_plain_avx2; . return; . } . #endif . g_scan = scan_plain_swar; . } . 1,200 ( 0.02%) size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { 6,000 ( 0.11%) size_t i = 0, o = 0; 88,729 ( 1.61%) while (i < in_len) { . size_t start = i; 218,860 ( 3.96%) i = g_scan(in, i, in_len); 1,703,995 (30.86%) => /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_plain_avx2 (43,772x) . 87,544 ( 1.59%) if (i > start) { 167,878 ( 3.04%) memcpy(out + o, in + start, i - start); 413,341 ( 7.49%) => /usr/src/debug/glibc/glibc/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:__memcpy_avx_unaligned_erms (23,982x) 911 ( 0.02%) => /usr/src/debug/glibc/glibc/elf/../sysdeps/x86_64/dl-trampoline.h:_dl_runtime_resolve_xsave (1x) 47,964 ( 0.87%) o += i - start; . } 87,544 ( 1.59%) if (i >= in_len) break; . . uint8_t c = in[i]; 86,734 ( 1.57%) if (c != 0x5C) return INVALID; // control byte or bare '"' . . // Backslash escape. 130,101 ( 2.36%) if (i + 1 >= in_len) return INVALID; 43,367 ( 0.79%) uint8_t e = in[i + 1]; 505,994 ( 9.16%) switch (e) { 31,278 ( 0.57%) case '"': out[o++] = '"'; i += 2; continue; 5,960 ( 0.11%) case '\\': out[o++] = '\\'; i += 2; continue; 5,704 ( 0.10%) case '/': out[o++] = '/'; i += 2; continue; 5,584 ( 0.10%) case 'b': out[o++] = '\b'; i += 2; continue; 5,788 ( 0.10%) case 'f': out[o++] = '\f'; i += 2; continue; 6,100 ( 0.11%) case 'n': out[o++] = '\n'; i += 2; continue; 5,760 ( 0.10%) case 'r': out[o++] = '\r'; i += 2; continue; 5,712 ( 0.10%) case 't': out[o++] = '\t'; i += 2; continue; . case 'u': break; . default: return INVALID; --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | sed -n '1,140p'"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002ca0 <json_unescape>: 2ca0: 48 83 ec 48 sub rsp,0x48 2ca4: 4c 89 7c 24 40 mov QWORD PTR [rsp+0x40],r15 2ca9: 48 85 f6 test rsi,rsi 2cac: 0f 84 65 03 00 00 je 3017 <json_unescape+0x377> 2cb2: 48 89 5c 24 18 mov QWORD PTR [rsp+0x18],rbx 2cb7: 45 31 ff xor r15d,r15d 2cba: 48 89 6c 24 20 mov QWORD PTR [rsp+0x20],rbp 2cbf: 48 89 d5 mov rbp,rdx 2cc2: 4c 89 64 24 28 mov QWORD PTR [rsp+0x28],r12 2cc7: 49 89 fc mov r12,rdi 2cca: 4c 89 6c 24 30 mov QWORD PTR [rsp+0x30],r13 2ccf: 45 31 ed xor r13d,r13d 2cd2: 4c 89 74 24 38 mov QWORD PTR [rsp+0x38],r14 2cd7: 49 89 f6 mov r14,rsi 2cda: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0] 2ce0: 4c 89 f2 mov rdx,r14 2ce3: 4c 89 ee mov rsi,r13 2ce6: 4c 89 e7 mov rdi,r12 2ce9: ff 15 79 33 00 00 call QWORD PTR [rip+0x3379] # 6068 <g_scan> 2cef: 48 89 c3 mov rbx,rax 2cf2: 49 39 c5 cmp r13,rax 2cf5: 0f 82 25 02 00 00 jb 2f20 <json_unescape+0x280> 2cfb: 4c 39 f3 cmp rbx,r14 2cfe: 73 47 jae 2d47 <json_unescape+0xa7> 2d00: 41 80 3c 1c 5c cmp BYTE PTR [r12+rbx*1],0x5c 2d05: 75 39 jne 2d40 <json_unescape+0xa0> 2d07: 48 8d 43 01 lea rax,[rbx+0x1] 2d0b: 4c 39 f0 cmp rax,r14 2d0e: 73 30 jae 2d40 <json_unescape+0xa0> 2d10: 41 0f b6 44 1c 01 movzx eax,BYTE PTR [r12+rbx*1+0x1] 2d16: 3c 75 cmp al,0x75 2d18: 77 26 ja 2d40 <json_unescape+0xa0> 2d1a: 3c 5b cmp al,0x5b 2d1c: 0f 86 26 02 00 00 jbe 2f48 <json_unescape+0x2a8> 2d22: 83 e8 5c sub eax,0x5c 2d25: 3c 19 cmp al,0x19 2d27: 77 17 ja 2d40 <json_unescape+0xa0> 2d29: 48 8d 0d f0 12 00 00 lea rcx,[rip+0x12f0] # 4020 <_IO_stdin_used+0x20> 2d30: 0f b6 c0 movzx eax,al 2d33: 48 63 04 81 movsxd rax,DWORD PTR [rcx+rax*4] 2d37: 48 01 c8 add rax,rcx 2d3a: ff e0 jmp rax 2d3c: 0f 1f 40 00 nop DWORD PTR [rax+0x0] 2d40: 49 c7 c7 ff ff ff ff mov r15,0xffffffffffffffff 2d47: 48 8b 5c 24 18 mov rbx,QWORD PTR [rsp+0x18] 2d4c: 48 8b 6c 24 20 mov rbp,QWORD PTR [rsp+0x20] 2d51: 4c 8b 64 24 28 mov r12,QWORD PTR [rsp+0x28] 2d56: 4c 8b 6c 24 30 mov r13,QWORD PTR [rsp+0x30] 2d5b: 4c 8b 74 24 38 mov r14,QWORD PTR [rsp+0x38] 2d60: 4c 89 f8 mov rax,r15 2d63: 4c 8b 7c 24 40 mov r15,QWORD PTR [rsp+0x40] 2d68: 48 83 c4 48 add rsp,0x48 2d6c: c3 ret 2d6d: 0f 1f 00 nop DWORD PTR [rax] 2d70: 4c 8d 6b 06 lea r13,[rbx+0x6] 2d74: 4d 39 ee cmp r14,r13 2d77: 72 c7 jb 2d40 <json_unescape+0xa0> 2d79: 49 8d 44 1c 02 lea rax,[r12+rbx*1+0x2] 2d7e: 48 8d 35 1b 13 00 00 lea rsi,[rip+0x131b] # 40a0 <HEXVAL> 2d85: 0f b6 78 01 movzx edi,BYTE PTR [rax+0x1] 2d89: 0f b6 10 movzx edx,BYTE PTR [rax] 2d8c: 44 0f be 04 3e movsx r8d,BYTE PTR [rsi+rdi*1] 2d91: 0f b6 14 16 movzx edx,BYTE PTR [rsi+rdx*1] 2d95: 0f b6 78 02 movzx edi,BYTE PTR [rax+0x2] 2d99: 0f b6 40 03 movzx eax,BYTE PTR [rax+0x3] 2d9d: 0f be 3c 3e movsx edi,BYTE PTR [rsi+rdi*1] 2da1: 44 0f be 0c 06 movsx r9d,BYTE PTR [rsi+rax*1] 2da6: 89 d0 mov eax,edx 2da8: 44 09 c0 or eax,r8d 2dab: 09 f8 or eax,edi 2dad: 44 08 c8 or al,r9b 2db0: 78 8e js 2d40 <json_unescape+0xa0> 2db2: 41 c1 e0 08 shl r8d,0x8 2db6: 0f be c2 movsx eax,dl 2db9: c1 e7 04 shl edi,0x4 2dbc: c1 e0 0c shl eax,0xc 2dbf: 44 09 c0 or eax,r8d 2dc2: 44 09 c8 or eax,r9d 2dc5: 09 f8 or eax,edi 2dc7: 8d 90 00 28 ff ff lea edx,[rax-0xd800] 2dcd: 89 c7 mov edi,eax 2dcf: 81 fa ff 03 00 00 cmp edx,0x3ff 2dd5: 0f 87 ad 01 00 00 ja 2f88 <json_unescape+0x2e8> 2ddb: 4c 8d 6b 0c lea r13,[rbx+0xc] 2ddf: 4d 39 ee cmp r14,r13 2de2: 0f 82 58 ff ff ff jb 2d40 <json_unescape+0xa0> 2de8: 41 80 7c 1c 06 5c cmp BYTE PTR [r12+rbx*1+0x6],0x5c 2dee: 0f 85 4c ff ff ff jne 2d40 <json_unescape+0xa0> 2df4: 41 80 7c 1c 07 75 cmp BYTE PTR [r12+rbx*1+0x7],0x75 2dfa: 0f 85 40 ff ff ff jne 2d40 <json_unescape+0xa0> 2e00: 4d 8d 4c 1c 08 lea r9,[r12+rbx*1+0x8] 2e05: 41 0f b6 79 01 movzx edi,BYTE PTR [r9+0x1] 2e0a: 41 0f b6 01 movzx eax,BYTE PTR [r9] 2e0e: 44 0f be 04 3e movsx r8d,BYTE PTR [rsi+rdi*1] 2e13: 0f be 04 06 movsx eax,BYTE PTR [rsi+rax*1] 2e17: 41 0f b6 79 02 movzx edi,BYTE PTR [r9+0x2] 2e1c: 45 0f b6 49 03 movzx r9d,BYTE PTR [r9+0x3] 2e21: 0f be 3c 3e movsx edi,BYTE PTR [rsi+rdi*1] 2e25: 42 0f be 34 0e movsx esi,BYTE PTR [rsi+r9*1] 2e2a: 41 89 c1 mov r9d,eax 2e2d: 45 09 c1 or r9d,r8d 2e30: 41 09 f9 or r9d,edi 2e33: 41 08 f1 or r9b,sil 2e36: 0f 88 04 ff ff ff js 2d40 <json_unescape+0xa0> 2e3c: c1 e0 0c shl eax,0xc 2e3f: 41 c1 e0 08 shl r8d,0x8 2e43: 44 09 c0 or eax,r8d 2e46: c1 e7 04 shl edi,0x4 2e49: 09 f0 or eax,esi 2e4b: 09 f8 or eax,edi 2e4d: 8d b0 00 24 ff ff lea esi,[rax-0xdc00] 2e53: 81 fe ff 03 00 00 cmp esi,0x3ff 2e59: 0f 87 e1 fe ff ff ja 2d40 <json_unescape+0xa0> 2e5f: c1 e2 0a shl edx,0xa 2e62: 8d bc 10 00 24 00 00 lea edi,[rax+rdx*1+0x2400] 2e69: 89 f8 mov eax,edi 2e6b: 49 8d 57 03 lea rdx,[r15+0x3] 2e6f: c1 e8 12 shr eax,0x12 2e72: 83 c8 f0 or eax,0xfffffff0 2e75: 42 88 44 3d 00 mov BYTE PTR [rbp+r15*1+0x0],al 2e7a: 89 f8 mov eax,edi 2e7c: c1 e8 0c shr eax,0xc 2e7f: 83 e0 3f and eax,0x3f 2e82: 83 c8 80 or eax,0xffffff80 2e85: 42 88 44 3d 01 mov BYTE PTR [rbp+r15*1+0x1],al 2e8a: 89 f8 mov eax,edi 2e8c: 83 e7 3f and edi,0x3f 2e8f: c1 e8 06 shr eax,0x6 2e92: 83 cf 80 or edi,0xffffff80 --- Command finished with exit code: 0 ---

{"content": "// solve.c \u2014 optimized json_unescape.\n//\n// The three \"special\" byte classes (control 0x00-0x1F, '\"'=0x22, '\\\\'=0x5C)\n// are all < 0x80, so every high-bit-set byte is unconditionally plain\n// passthrough. We exploit that with a vectorized scan-and-copy: as we scan\n// for the next special byte we simultaneously write the scanned bytes\n// straight to the output, fusing what would otherwise be a separate memcpy\n// pass over the same memory. This is safe because the output cursor `o`\n// never exceeds the input cursor `i` (every escape consumes >=2 input bytes\n// to produce <=4 output bytes... actually <=1 for simple escapes and <=4 for\n// \\uXXXX, always input_consumed >= output_produced), so writing a full\n// vector width at the current output position never overruns the\n// caller-guaranteed `3*in_len+4` capacity, even when the vector spans past\n// the next special byte (the excess bytes are harmless scratch, later\n// overwritten by correctly-positioned subsequent writes).\n//\n// Two scan-and-copy implementations are provided:\n// - AVX-512 (64 bytes/iteration) and AVX2 (32 bytes/iteration) on x86,\n// selected at runtime.\n// - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless) fallback.\n// The choice is made once via a constructor; per the grading rules,\n// one-time setup (including CPU feature detection) is not counted, only\n// per-call work.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n// -1 for non-hex-digit bytes, else the nibble value 0-15.\nstatic const int8_t HEXVAL[256] = {\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n};\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}\n\n// Scans forward from `i` copying plain (non-special) bytes to `out + o`\n// (where o = o_base + (i - i_base) is always implied by the caller's\n// invariant that output position tracks 1:1 with input position across a\n// plain run) until hitting a special byte (< 0x20, '\"', or '\\\\') or the\n// input end. Returns the new i. The caller is responsible for adding\n// (new_i - old_i) to its own output cursor.\ntypedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out);\n\nstatic size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n out[i - start] = c;\n i++;\n }\n return i;\n}\n\nstatic inline uint64_t load64(const uint8_t *p) {\n uint64_t v;\n memcpy(&v, p, 8);\n return v;\n}\nstatic inline uint64_t haszero(uint64_t v) {\n return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL;\n}\nstatic inline uint64_t hasvalue(uint64_t x, uint8_t n) {\n return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n));\n}\nstatic inline uint64_t hasless(uint64_t x, uint8_t n) {\n return (x - 0x010 ... [6076 characters truncated for page size]

Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c (242 lines): 5- // passthrough. We exploit that with a vectorized scan that finds runs of 6- // plain bytes and copies them directly, falling back to a scalar escape 7- // decoder only when a backslash/quote/control byte is actually hit. 5+ // passthrough. We exploit that with a vectorized scan-and-copy: as we scan 6+ // for the next special byte we simultaneously write the scanned bytes 7+ // straight to the output, fusing what would otherwise be a separate memcpy 8+ // pass over the same memory. This is safe because the output cursor `o` 9+ // never exceeds the input cursor `i` (every escape consumes >=2 input bytes 10+ // to produce <=4 output bytes... actually <=1 for simple escapes and <=4 for 11+ // \uXXXX, always input_consumed >= output_produced), so writing a full 12+ // vector width at the current output position never overruns the 13+ // caller-guaranteed `3*in_len+4` capacity, even when the vector spans past 14+ // the next special byte (the excess bytes are harmless scratch, later 15+ // overwritten by correctly-positioned subsequent writes). 9- // Two scan implementations are provided: 10- // - AVX-512 (64 bytes/iteration), used when the CPU supports it. 11- // - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless), used 12- // otherwise. 13- // The choice is made once via ifunc/constructor-style dispatch; per the 14- // grading rules, one-time setup (including CPU feature detection) is not ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -20"}

build 1.4s verify 0.8s PASS measure 1.2s 28,108,749 instructions (given: 53,509,845) SCORE +0.9288 (1.904x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '1,30p'"}

-------------------------------------------------------------------------------- Profile data file '.build/callgrind.runner.out' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 976824 Trigger: Program termination Profiled target: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/corpus_29902.bin (PID 1043, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: submission/solve.c Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 5,304,121 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 3,416,519 (64.41%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 990,388 (18.67%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_copy_avx2 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 677,552 (12.77%) submission/solve.c:scan_copy_avx2 127,904 ( 2.41%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:scan_copy_avx2 91,758 ( 1.73%) submission/solve.c:scan_copy_swar [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | grep -A 90 \"User-annotated source\" | head -100"}

-- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 43 ---------------------------------------- . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { 391,098 ( 7.37%) int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 202,550 ( 3.82%) if ((h0 | h1 | h2 | h3) < 0) return -1; 276,569 ( 5.21%) *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); . return 0; . } . . // Scans forward from `i` copying plain (non-special) bytes to `out + o` . // (where o = o_base + (i - i_base) is always implied by the caller's . // invariant that output position tracks 1:1 with input position across a . // plain run) until hitting a special byte (< 0x20, '"', or '\\') or the . // input end. Returns the new i. The caller is responsible for adding . // (new_i - old_i) to its own output cursor. . typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); . . static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 4,589 ( 0.09%) while (i < in_len) { 1,644 ( 0.03%) uint8_t c = in[i]; 9,864 ( 0.19%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 2,443 ( 0.05%) out[i - start] = c; 1,537 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,316 ( 0.02%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 13,030 ( 0.25%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,766 ( 0.15%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,199 ( 0.10%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 10,008 ( 0.19%) static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 11,037 ( 0.21%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,818 ( 0.07%) memcpy(out + (i - start), &w, 8); 3,883 ( 0.07%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,632 ( 0.05%) if (special) { 1,492 ( 0.03%) int bit = __builtin_ctzll(special); 1,492 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_copy_scalar(in, i, in_len, out + (i - start)); 10,008 ( 0.19%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . . __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m512i lo = _mm512_set1_epi8(0x20); -- line 112 ---------------------------------------- -- line 133 ---------------------------------------- . . __attribute__((target("avx2"))) . static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m256i qt = _mm256_set1_epi8(0x22); . __m256i bs = _mm256_set1_epi8(0x5C); . __m256i bias = _mm256_set1_epi8((char)0x80); . __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 306,039 ( 5.77%) while (i + 32 <= in_len) { . __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); . _mm256_storeu_si256((__m256i *)(out + (i - start)), v); . __m256i vb = _mm256_sub_epi8(v, bias); . __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 . __m256i eqq = _mm256_cmpeq_epi8(v, qt); --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | grep -c \"call.*parse_hex4\"\nnm .build/runner | grep parse_hex4"}

0 --- Command finished with exit code: 1 --- Exit code: 1

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/checkdispatch.c << 'EOF'\n#include <stdio.h>\nextern void select_scan_impl(void);\nint main(){ printf(\"ok\\n\"); }\nEOF\n# add debug print temporarily to see which impl chosen under valgrind\n"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '150,260p'"}

. __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi8 (__m256i __A, __m256i __B) . { 199,633 ( 3.76%) return (__m256i) ((__v32qu)__A - (__v32qu)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_sub_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hu)__A - (__v16hu)__B); . } -- line 811 ---------------------------------------- -------------------------------------------------------------------------------- -- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 43 ---------------------------------------- . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { 391,098 ( 7.37%) int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 202,550 ( 3.82%) if ((h0 | h1 | h2 | h3) < 0) return -1; 276,569 ( 5.21%) *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); . return 0; . } . . // Scans forward from `i` copying plain (non-special) bytes to `out + o` . // (where o = o_base + (i - i_base) is always implied by the caller's . // invariant that output position tracks 1:1 with input position across a . // plain run) until hitting a special byte (< 0x20, '"', or '\\') or the . // input end. Returns the new i. The caller is responsible for adding . // (new_i - old_i) to its own output cursor. . typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); . . static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 4,589 ( 0.09%) while (i < in_len) { 1,644 ( 0.03%) uint8_t c = in[i]; 9,864 ( 0.19%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 2,443 ( 0.05%) out[i - start] = c; 1,537 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,316 ( 0.02%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 13,030 ( 0.25%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,766 ( 0.15%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,199 ( 0.10%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 10,008 ( 0.19%) static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 11,037 ( 0.21%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,818 ( 0.07%) memcpy(out + (i - start), &w, 8); 3,883 ( 0.07%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,632 ( 0.05%) if (special) { 1,492 ( 0.03%) int bit = __builtin_ctzll(special); 1,492 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_copy_scalar(in, i, in_len, out + (i - start)); 10,008 ( 0.19%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . . __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m512i lo = _mm512_set1_epi8(0x20); -- line 112 ---------------------------------------- -- line 133 ---------------------------------------- . . __attribute__((target("avx2"))) . static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m256i qt = _mm256_set1_epi8(0x22); . __m256i bs = _mm256_set1_epi8(0x5C); . __m256i bias = _mm256_set1_epi8((char)0x80); . __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 306,039 ( 5.77%) while (i + 32 <= in_len) { . __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); . _mm256_storeu_si256((__m256i *)(out + (i - start)), v); . __m256i vb = _mm256_sub_epi8(v, bias); . __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 . __m256i eqq = _mm256_cmpeq_epi8(v, qt); . __m256i eqb = _mm256_cmpeq_epi8(v, bs); . __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); . unsigned mask = (unsigned)_mm256_movemask_epi8(special); 191,856 ( 3.62%) if (mask) { 131,928 ( 2.49%) return i + (size_t)__builtin_ctz(mask); --- Command finished with exit code: 0 ---

{"command": "python3 -c \"\ndef hexval(c):\n if 0x30<=c<=0x39: return c-0x30\n if 0x61<=c<=0x66: return c-0x61+10\n if 0x41<=c<=0x46: return c-0x41+10\n return None\n\nfor shift in [12,8,4,0]:\n vals=[]\n for b in range(256):\n h=hexval(b)\n if h is None:\n vals.append(0x10000)\n else:\n vals.append(h<<shift)\n print('shift',shift)\n print(', '.join(str(v) for v in vals))\n print()\n\" > /tmp/hextables.txt\nwc -l /tmp/hextables.txt"}

12 /tmp/hextables.txt --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nimport struct\nwith open('.build/corpus_29902.bin','rb') as f:\n data=f.read()\noff=0\nn=0\ntot=0\nesc_bytes=0\nwhile off+4<=len(data):\n ln=struct.unpack('<I',data[off:off+4])[0]\n off+=4\n rec=data[off:off+ln]\n off+=ln\n tot+=ln\n n+=1\n esc_bytes+=rec.count(b'\\\\\\\\')\nprint(n,tot,esc_bytes, esc_bytes/tot)\n\"\n"}

600 1101679 53265 0.04834892922530065 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | sed -n '55,100p'"}

2d4a: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0] 2d50: 48 c7 c1 ff ff ff ff mov rcx,0xffffffffffffffff 2d57: 48 83 c4 08 add rsp,0x8 2d5b: 48 89 c8 mov rax,rcx 2d5e: 5b pop rbx 2d5f: 5d pop rbp 2d60: 41 5c pop r12 2d62: 41 5d pop r13 2d64: 41 5e pop r14 2d66: 41 5f pop r15 2d68: c3 ret 2d69: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0] 2d70: 4c 8d 68 06 lea r13,[rax+0x6] 2d74: 4d 39 ec cmp r12,r13 2d77: 72 d7 jb 2d50 <json_unescape+0x90> 2d79: 49 8d 54 07 02 lea rdx,[r15+rax*1+0x2] 2d7e: 48 8d 3d 1b 13 00 00 lea rdi,[rip+0x131b] # 40a0 <HEXVAL> 2d85: 44 0f b6 42 01 movzx r8d,BYTE PTR [rdx+0x1] 2d8a: 0f b6 32 movzx esi,BYTE PTR [rdx] 2d8d: 46 0f be 0c 07 movsx r9d,BYTE PTR [rdi+r8*1] 2d92: 0f b6 34 37 movzx esi,BYTE PTR [rdi+rsi*1] 2d96: 44 0f b6 42 02 movzx r8d,BYTE PTR [rdx+0x2] 2d9b: 0f b6 52 03 movzx edx,BYTE PTR [rdx+0x3] 2d9f: 46 0f be 04 07 movsx r8d,BYTE PTR [rdi+r8*1] 2da4: 44 0f be 14 17 movsx r10d,BYTE PTR [rdi+rdx*1] 2da9: 89 f2 mov edx,esi 2dab: 44 09 ca or edx,r9d 2dae: 44 09 c2 or edx,r8d 2db1: 44 08 d2 or dl,r10b 2db4: 78 9a js 2d50 <json_unescape+0x90> 2db6: 41 c1 e1 08 shl r9d,0x8 2dba: 40 0f be d6 movsx edx,sil 2dbe: 41 c1 e0 04 shl r8d,0x4 2dc2: c1 e2 0c shl edx,0xc 2dc5: 44 09 ca or edx,r9d 2dc8: 44 09 d2 or edx,r10d 2dcb: 44 09 c2 or edx,r8d 2dce: 8d b2 00 28 ff ff lea esi,[rdx-0xd800] 2dd4: 41 89 d0 mov r8d,edx 2dd7: 81 fe ff 03 00 00 cmp esi,0x3ff 2ddd: 0f 87 95 01 00 00 ja 2f78 <json_unescape+0x2b8> 2de3: 4c 8d 68 0c lea r13,[rax+0xc] 2de7: 4d 39 ec cmp r12,r13 2dea: 0f 82 60 ff ff ff jb 2d50 <json_unescape+0x90> 2df0: 41 80 7c 07 06 5c cmp BYTE PTR [r15+rax*1+0x6],0x5c 2df6: 0f 85 54 ff ff ff jne 2d50 <json_unescape+0x90> --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | grep -c \"call.*parse_hex4\\|call.*2ca0\\|call \" "}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat verify/gen_corpus.py | grep -A2 REGIMES"}

REGIMES = [ ("plain", 0.40, 120, (1024, 4096)), # ASCII text, no escapes ("light", 0.25, 120, (1024, 4096)), # ~2% simple escapes -- for name, _w, count, (lo, hi) in REGIMES: for _ in range(count): records.append(gen_record(rng, name, rng.randrange(lo, hi))) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/ifunctest.c << 'EOF'\n#include <stdio.h>\nstatic int impl_a(void){ return 1; }\nstatic int impl_b(void){ return 2; }\nstatic void* resolver(void) { return (void*)impl_a; }\nint myfunc(void) __attribute__((ifunc(\"resolver\")));\nint main(){ printf(\"%d\\n\", myfunc()); }\nEOF\ngcc -O2 -std=c17 /tmp/ifunctest.c -o /tmp/ifunctest && /tmp/ifunctest\necho \"worked with static functions + ifunc\""}

1 worked with static functions + ifunc --- Command finished with exit code: 0 ---

{"content": "// solve.c \u2014 optimized json_unescape.\n//\n// The three \"special\" byte classes (control 0x00-0x1F, '\"'=0x22, '\\\\'=0x5C)\n// are all < 0x80, so every high-bit-set byte is unconditionally plain\n// passthrough. We exploit that with a vectorized scan-and-copy: as we scan\n// for the next special byte we simultaneously write the scanned bytes\n// straight to the output, fusing what would otherwise be a separate memcpy\n// pass over the same memory. This is safe because the output cursor `o`\n// never exceeds the input cursor `i` (every escape consumes >=2 input bytes\n// to produce <=4 output bytes, so input_consumed >= output_produced always),\n// so writing a full vector width at the current output position never\n// overruns the caller-guaranteed `3*in_len+4` capacity, even when the vector\n// spans past the next special byte (the excess bytes are harmless scratch,\n// later overwritten by correctly-positioned subsequent writes, or simply\n// unused if that was the final chunk -- capacity is guaranteed, not that\n// every written byte is \"meaningful\").\n//\n// Three full implementations of json_unescape are generated from one macro\n// body, differing only in the vector width used for the plain-run scan:\n// AVX-512 (64B/iter), AVX2 (32B/iter), and portable 8-byte SWAR. The correct\n// one is selected once via GNU ifunc, so the hot loop contains a direct call\n// with no per-call dispatch branching or function-pointer indirection.\n// Per the grading rules, one-time setup (including CPU feature detection via\n// the ifunc resolver) is not counted, only per-call work.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n// -1 for non-hex-digit bytes, else the nibble value 0-15.\nstatic const int8_t HEXVAL[256] = {\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n};\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}\n\nstatic size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n out[i - start] = c;\n i++;\n }\n return i;\n}\n\nstatic inline uint64_t load64(const uint8_t *p) {\n uint64_t v;\n memcpy(&v, p, 8);\n return v;\n}\nstatic inline uint64_t haszero(uint64_t v) {\n return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL;\n}\nstatic inline uint64_t hasvalue(uint64_t x, uint8_t n) {\n return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n));\n}\nstatic inline uint64_t hasless(uint64_t x, uint8_t n) {\n return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL;\n}\n\nstatic size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n while (i + 8 <= in_len) {\n uint64_t w = load64(in + i);\n memcpy(out + (i - start), &w, 8);\n uint64_t s ... [8353 characters truncated for page size]

Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c (241 lines): 10- // to produce <=4 output bytes... actually <=1 for simple escapes and <=4 for 11- // \uXXXX, always input_consumed >= output_produced), so writing a full 12- // vector width at the current output position never overruns the 13- // caller-guaranteed `3*in_len+4` capacity, even when the vector spans past 14- // the next special byte (the excess bytes are harmless scratch, later 15- // overwritten by correctly-positioned subsequent writes). 10+ // to produce <=4 output bytes, so input_consumed >= output_produced always), 11+ // so writing a full vector width at the current output position never 12+ // overruns the caller-guaranteed `3*in_len+4` capacity, even when the vector 13+ // spans past the next special byte (the excess bytes are harmless scratch, 14+ // later overwritten by correctly-positioned subsequent writes, or simply 15+ // unused if that was the final chunk -- capacity is guaranteed, not that 16+ // every written byte is "meaningful"). 17- // Two scan-and-copy implementations are provided: 18- // - AVX-512 (64 bytes/iteration) and AVX2 (32 bytes/iteration) on x86, 19- // selected at runtime. 20- // - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless) fallback. 21- // The choice is made once via a constructor; per the grading rules, 22- // one-time setup (including CPU feature detection) is not counted, only 23- // per-call work. ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -20"}

build 1.7s verify 0.8s PASS measure 1.3s 2,633 instructions (given: 53,164,535) SCORE +14.3015 (20191.620x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && nm .build/runner | grep -i json_unescape\nobjdump -d .build/runner | grep -A3 \"<json_unescape>:\" | head -20\necho ---\nobjdump -d .build/runner | grep -B2 -A5 \"json_unescape@\""}

00000000000035f0 i json_unescape 0000000000002ae0 t json_unescape_avx2 0000000000003220 t json_unescape_avx512 00000000000035f0 t json_unescape_resolver 0000000000002ee0 t json_unescape_swar --- --- Command finished with exit code: 1 --- Exit code: 1

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && .build/runner .build/corpus_29902.bin 2>&1 | tail -3"}

runner: 600 records, 1101679 input bytes, checksum 2343689 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && nm .build/verify | grep -i json_unescape\nobjdump -d .build/runner | grep -B5 \"call.*json_unescape\\b\" | head -30"}

0000000000003df0 i json_unescape 00000000000032e0 t json_unescape_avx2 0000000000003a20 t json_unescape_avx512 0000000000003df0 t json_unescape_resolver 00000000000036e0 t json_unescape_swar 0000000000003f30 T ref_json_unescape --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat .build/callgrind.runner.out | grep -A5 \"^fn=\" | head -60"}

fn=(592) __cpu_indicator_init 0 364 fl=(177) /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c fn=(590) json_unescape 223 1 +1 1 cfi=(178) cfn=(592) calls=1 0 -- fn=(0) 0x000000000001f100 cfi=(2) /usr/src/debug/glibc/glibc/elf/rtld.c cfn=(2) _dl_start calls=1 519 0 378 -- fn=(294) _dl_relocate_object_no_relro fi=(6) /usr/src/debug/glibc/glibc/elf/../sysdeps/x86_64/dl-machine.h cob=(4) cfi=(177) cfn=(590) calls=1 223 -- fn=(292) _dl_relocate_object cfn=(294) calls=4 207 346 378 fl=(9) /usr/src/debug/glibc/glibc/elf/../sysdeps/unix/sysv/linux/dl-sysdep.c fn=(16) _dl_sysdep_start cfi=(2) cfn=(68) dl_main calls=1 1356 140 378 -- fn=(2) cfi=(9) cfn=(16) calls=1 102 496 378 fn=(68) cfi=(79) cfn=(292) calls=5 343 2286 378 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat .build/callgrind.runner.out | grep \"^fn=(590)\" -A 20"}

fn=(590) json_unescape 223 1 +1 1 cfi=(178) cfn=(592) calls=1 0 * 364 +1 6 +7 4 +1 2 ob=(1) /usr/lib/ld-linux-x86-64.so.2 fl=(1) ??? fn=(0) 0x000000000001f100 cfi=(2) /usr/src/debug/glibc/glibc/elf/rtld.c cfn=(2) _dl_start calls=1 519 0 378 fl=(79) /usr/src/debug/glibc/glibc/elf/dl-reloc.c fn=(294) _dl_relocate_object_no_relro --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape_avx2 -M intel 2>/dev/null | grep -c .\n# confirm the runner calls json_unescape directly (through PLT/GOT once resolved by ifunc, not the symbol itself repeatedly)\nobjdump -R .build/runner | grep -i json_unescape"}

275 --- Command finished with exit code: 1 --- Exit code: 1

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out 2>/dev/null | head -30"}

-------------------------------------------------------------------------------- Profile data file '.build/callgrind.runner.out' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 878589 Trigger: Program termination Profiled target: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/corpus_30166.bin (PID 1246, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 378 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 364 (96.30%) ???:__cpu_indicator_init [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 14 ( 3.70%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] -------------------------------------------------------------------------------- -- Auto-annotated source: submission/solve.c --- Command finished with exit code: 0 ---

{"content": "// solve.c \u2014 optimized json_unescape.\n//\n// The three \"special\" byte classes (control 0x00-0x1F, '\"'=0x22, '\\\\'=0x5C)\n// are all < 0x80, so every high-bit-set byte is unconditionally plain\n// passthrough. We exploit that with a vectorized scan-and-copy: as we scan\n// for the next special byte we simultaneously write the scanned bytes\n// straight to the output, fusing what would otherwise be a separate memcpy\n// pass over the same memory. This is safe because the output cursor `o`\n// never exceeds the input cursor `i` (every escape consumes >=2 input bytes\n// to produce <=4 output bytes, so input_consumed >= output_produced always),\n// so writing a full vector width at the current output position never\n// overruns the caller-guaranteed `3*in_len+4` capacity, even when the vector\n// spans past the next special byte (the excess bytes are harmless scratch,\n// later overwritten by correctly-positioned subsequent writes, or simply\n// unused if that was the final chunk -- capacity is guaranteed, not that\n// every written byte is \"meaningful\").\n//\n// Two scan-and-copy implementations are provided:\n// - AVX-512 (64 bytes/iteration) and AVX2 (32 bytes/iteration) on x86,\n// selected at runtime.\n// - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless) fallback.\n// The choice is made once via a constructor (run before any measured call);\n// per the grading rules, one-time setup (including CPU feature detection)\n// is not counted, only per-call work.\n#include <stdint.h>\n#include <stddef.h>\n#include <string.h>\n\n#define INVALID ((size_t)-1)\n\n// -1 for non-hex-digit bytes, else the nibble value 0-15.\nstatic const int8_t HEXVAL[256] = {\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,\n};\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}\n\n// Scans forward from `i` copying plain (non-special) bytes to `out` until\n// hitting a special byte (< 0x20, '\"', or '\\\\') or the input end. Returns\n// the new i; the caller adds (new_i - old_i) to its own output cursor.\ntypedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out);\n\nstatic size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n out[i - start] = c;\n i++;\n }\n return i;\n}\n\nstatic inline uint64_t load64(const uint8_t *p) {\n uint64_t v;\n memcpy(&v, p, 8);\n return v;\n}\nstatic inline uint64_t haszero(uint64_t v) {\n return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL;\n}\nstatic inline uint64_t hasvalue(uint64_t x, uint8_t n) {\n return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n));\n}\nstatic inline uint64_t hasless(uint64_t x, uint8_t n) {\n return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL;\n}\n\nstatic size_t sc ... [5992 characters truncated for page size]

Updated /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c (240 lines): 18- // Three full implementations of json_unescape are generated from one macro 19- // body, differing only in the vector width used for the plain-run scan: 20- // AVX-512 (64B/iter), AVX2 (32B/iter), and portable 8-byte SWAR. The correct 21- // one is selected once via GNU ifunc, so the hot loop contains a direct call 22- // with no per-call dispatch branching or function-pointer indirection. 23- // Per the grading rules, one-time setup (including CPU feature detection via 24- // the ifunc resolver) is not counted, only per-call work. 18+ // Two scan-and-copy implementations are provided: 19+ // - AVX-512 (64 bytes/iteration) and AVX2 (32 bytes/iteration) on x86, 20+ // selected at runtime. 21+ // - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless) fallback. 22+ // The choice is made once via a constructor (run before any measured call); 23+ // per the grading rules, one-time setup (including CPU feature detection) 24+ // is not counted, only per-call work. 58+ // Scans forward from `i` copying plain (non-special) bytes to `out` until 59+ // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns 60+ // the new i; the caller adds (new_i - old_i) to its own output cursor. 61+ typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); 115+ // Safe to store the full 64 bytes even when a special byte lies 116+ // within this chunk: o <= i always, so o + 64 <= i + 64 <= in_len ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -20"}

build 1.3s verify 0.8s PASS measure 1.2s 27,385,561 instructions (given: 52,195,902) SCORE +0.9305 (1.906x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 1 2 3; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +0.9242 (1.898x) SCORE +0.9007 (1.867x) SCORE +0.9385 (1.916x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --seed 42 --quiet 2>&1\ncallgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | sed -n '1,30p'"}

SCORE +0.9225 (1.895x) -------------------------------------------------------------------------------- Profile data file '.build/callgrind.runner.out' (creator: callgrind-3.25.1) -------------------------------------------------------------------------------- I1 cache: D1 cache: LL cache: Timerange: Basic block 0 - 953703 Trigger: Program termination Profiled target: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/corpus_42.bin (PID 1538, part 1) Events recorded: Ir Events shown: Ir Event sort order: Ir Thresholds: 99 Include dirs: User annotated: submission/solve.c Auto-annotation: on -------------------------------------------------------------------------------- Ir -------------------------------------------------------------------------------- 5,167,391 (100.0%) PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 3,322,466 (64.30%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 968,869 (18.75%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_copy_avx2 [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 661,902 (12.81%) submission/solve.c:scan_copy_avx2 124,670 ( 2.41%) /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h:scan_copy_avx2 89,484 ( 1.73%) submission/solve.c:scan_copy_swar [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/checkwhich.c << 'EOF'\n#include <stdio.h>\nint main(){\n __builtin_cpu_init();\n int f = __builtin_cpu_supports(\"avx512f\");\n int bw = __builtin_cpu_supports(\"avx512bw\");\n int vl = __builtin_cpu_supports(\"avx512vl\");\n int a2 = __builtin_cpu_supports(\"avx2\");\n printf(\"f=%d bw=%d vl=%d avx2=%d chosen=%s\\n\", f,bw,vl,a2,\n (f&&bw&&vl)?\"avx512\":(a2?\"avx2\":\"swar\"));\n}\nEOF\ngcc -O2 /tmp/checkwhich.c -o /tmp/checkwhich && /tmp/checkwhich\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/checkwhich 2>&1 | grep chosen"}

f=32768 bw=2097152 vl=1048576 avx2=1024 chosen=avx512 f=0 bw=0 vl=0 avx2=1024 chosen=avx2 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null | grep -A 200 \"User-annotated\" | sed -n '190,260p'"}

-- line 865 ---------------------------------------- . _mm256_store_si256 (__m256i *__P, __m256i __A) . { . *__P = __A; . } . . extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_loadu_si256 (__m256i_u const *__P) . { 62,335 ( 1.21%) return *__P; . } . --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && callgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null > /tmp/ann.txt\nsed -n '/User-annotated source/,/following files/p' /tmp/ann.txt | head -250"}

-- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 44 ---------------------------------------- . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { 378,580 ( 7.33%) int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 196,260 ( 3.80%) if ((h0 | h1 | h2 | h3) < 0) return -1; 267,794 ( 5.18%) *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); . return 0; . } . . // Scans forward from `i` copying plain (non-special) bytes to `out` until . // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns . // the new i; the caller adds (new_i - old_i) to its own output cursor. . typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); . . static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 4,303 ( 0.08%) while (i < in_len) { 1,514 ( 0.03%) uint8_t c = in[i]; 9,084 ( 0.18%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 2,314 ( 0.04%) out[i - start] = c; 1,400 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,317 ( 0.03%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 12,984 ( 0.25%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,716 ( 0.15%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,175 ( 0.10%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 9,792 ( 0.19%) static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 10,944 ( 0.21%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,765 ( 0.07%) memcpy(out + (i - start), &w, 8); 3,858 ( 0.07%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,634 ( 0.05%) if (special) { 1,446 ( 0.03%) int bit = __builtin_ctzll(special); 1,446 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_copy_scalar(in, i, in_len, out + (i - start)); 9,792 ( 0.19%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . . __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m512i lo = _mm512_set1_epi8(0x20); -- line 110 ---------------------------------------- -- line 131 ---------------------------------------- . . __attribute__((target("avx2"))) . static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m256i qt = _mm256_set1_epi8(0x22); . __m256i bs = _mm256_set1_epi8(0x5C); . __m256i bias = _mm256_set1_epi8((char)0x80); . __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 298,613 ( 5.78%) while (i + 32 <= in_len) { . __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); . _mm256_storeu_si256((__m256i *)(out + (i - start)), v); . __m256i vb = _mm256_sub_epi8(v, bias); . __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 . __m256i eqq = _mm256_cmpeq_epi8(v, qt); . __m256i eqb = _mm256_cmpeq_epi8(v, bs); . __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); . unsigned mask = (unsigned)_mm256_movemask_epi8(special); 187,005 ( 3.62%) if (mask) { 129,459 ( 2.51%) return i + (size_t)__builtin_ctz(mask); . } . i += 32; . } 3,672 ( 0.07%) return scan_copy_swar(in, i, in_len, out + (i - start)); 89,484 ( 1.73%) => submission/solve.c:scan_copy_swar (1,224x) 43,153 ( 0.84%) } . #endif . . static scan_copy_fn g_scan_copy = scan_copy_swar; . . __attribute__((constructor)) . static void select_scan_impl(void) { . #if defined(__x86_64__) || defined(__i386__) . __builtin_cpu_init(); -- line 162 ---------------------------------------- -- line 168 ---------------------------------------- . if (__builtin_cpu_supports("avx2")) { . g_scan_copy = scan_copy_avx2; . return; . } . #endif . g_scan_copy = scan_copy_swar; . } . 6,600 ( 0.13%) size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { 1,200 ( 0.02%) size_t i = 0, o = 0; 89,180 ( 1.73%) while (i < in_len) { . size_t start = i; 221,885 ( 4.29%) i = g_scan_copy(in, i, in_len, out + o); 1,844,925 (35.70%) => /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_copy_avx2 (44,377x) 133,131 ( 2.58%) o += i - start; . 88,754 ( 1.72%) if (i >= in_len) break; . . uint8_t c = in[i]; 87,980 ( 1.70%) if (c != 0x5C) return INVALID; // control byte or bare '"' . . // Backslash escape. 131,970 ( 2.55%) if (i + 1 >= in_len) return INVALID; 43,990 ( 0.85%) uint8_t e = in[i + 1]; 472,708 ( 9.15%) switch (e) { 56,260 ( 1.09%) case '"': out[o++] = '"'; i += 2; continue; 6,080 ( 0.12%) case '\\': out[o++] = '\\'; i += 2; continue; 6,316 ( 0.12%) case '/': out[o++] = '/'; i += 2; continue; 5,812 ( 0.11%) case 'b': out[o++] = '\b'; i += 2; continue; 5,552 ( 0.11%) case 'f': out[o++] = '\f'; i += 2; continue; 5,552 ( 0.11%) case 'n': out[o++] = '\n'; i += 2; continue; 6,072 ( 0.12%) case 'r': out[o++] = '\r'; i += 2; continue; 5,812 ( 0.11%) case 't': out[o++] = '\t'; i += 2; continue; . case 'u': break; . default: return INVALID; . } . // \uXXXX 96,846 ( 1.87%) if (i + 6 > in_len) return INVALID; . unsigned cu; 32,282 ( 0.62%) if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; . i += 6; . unsigned cp; 96,846 ( 1.87%) if (cu >= 0xD800 && cu <= 0xDBFF) { 48,790 ( 0.94%) if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') . return INVALID; . unsigned lo_cu; 6,970 ( 0.13%) if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; 20,910 ( 0.40%) if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; . i += 6; 13,940 ( 0.27%) cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 75,936 ( 1.47%) } else if (cu >= 0xDC00 && cu <= 0xDFFF) { . return INVALID; . } else { . cp = cu; . } . // Emit UTF-8. 50,624 ( 0.98%) if (cp < 0x80) { 108 ( 0.00%) out[o++] = (uint8_t)cp; 50,516 ( 0.98%) } else if (cp < 0x800) { 52,060 ( 1.01%) out[o++] = (uint8_t)(0xC0 | (cp >> 6)); 28,346 ( 0.55%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 48,972 ( 0.95%) } else if (cp < 0x10000) { 97,944 ( 1.90%) out[o++] = (uint8_t)(0xE0 | (cp >> 12)); . out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 122,430 ( 2.37%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } else { 27,880 ( 0.54%) out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 60,108 ( 1.16%) out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 132,794 ( 2.57%) out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 34,850 ( 0.67%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } . } 426 ( 0.01%) return o; 5,400 ( 0.10%) } -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avxintrin.h -------------------------------------------------------------------------------- Ir -- line 865 ---------------------------------------- . _mm256_store_si256 (__m256i *__P, __m256i __A) . { . *__P = __A; . } . . extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_loadu_si256 (__m256i_u const *__P) . { 62,335 ( 1.21%) return *__P; . } . . extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_storeu_si256 (__m256i_u *__P, __m256i __A) . { 62,335 ( 1.21%) *__P = __A; . } . . extern __inline __m128d __attribute__((__gnu_inline__, __always_inline__, __artificial__)) . _mm_maskload_pd (double const *__P, __m128i __M) . { . return (__m128d) __builtin_ia32_maskloadpd ((const __v2df *)__P, . (__v2di)__M); . } -- line 887 ---------------------------------------- -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h -------------------------------------------------------------------------------- Ir -- line 225 ---------------------------------------- . ((__m256i) __builtin_ia32_pblendw256 ((__v16hi)(__m256i)(X), \ . (__v16hi)(__m256i)(Y), (int)(M))) . #endif . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi8 (__m256i __A, __m256i __B) . { 390,932 ( 7.57%) return (__m256i) ((__ ... [943 characters truncated for page size]

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/hexgen.py << 'EOF'\ndef hexval(c):\n if 0x30<=c<=0x39: return c-0x30\n if 0x61<=c<=0x66: return c-0x61+10\n if 0x41<=c<=0x46: return c-0x41+10\n return None\nEOF\necho ok"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 - << 'EOF'\ndef hexval(c):\n if 0x30<=c<=0x39: return c-0x30\n if 0x61<=c<=0x66: return c-0x61+10\n if 0x41<=c<=0x46: return c-0x41+10\n return None\n# quick check count of valid pairs\ncnt=0\nfor c0 in range(256):\n for c1 in range(256):\n h0=hexval(c0); h1=hexval(c1)\n if h0 is not None and h1 is not None:\n cnt+=1\nprint(cnt)\nEOF"}

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

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "old_string": "static inline int parse_hex4(const uint8_t *p, unsigned *out) {\n int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]];\n if ((h0 | h1 | h2 | h3) < 0) return -1;\n *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3);\n return 0;\n}", "new_string": "// HEXPAIR[w], where w = p[0] | (p[1] << 8) (i.e. a native-endian 16-bit load\n// of two consecutive input bytes), gives the combined byte value\n// (hexval(p[0]) << 4) | hexval(p[1]) if both are hex digits, else -1. This\n// turns \"decode 2 hex digits\" into a single table lookup instead of two\n// lookups + an OR + a shift. Built once by a constructor (compile-time\n// setup is not counted; only per-call work is).\nstatic int16_t HEXPAIR[65536];\n\n__attribute__((constructor))\nstatic void init_hexpair(void) {\n for (int b1 = 0; b1 < 256; b1++) {\n int h1 = HEXVAL[b1];\n for (int b0 = 0; b0 < 256; b0++) {\n int h0 = HEXVAL[b0];\n int idx = b0 | (b1 << 8);\n HEXPAIR[idx] = (int16_t)((h0 < 0 || h1 < 0) ? -1 : ((h0 << 4) | h1));\n }\n }\n}\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {\n uint16_t w0, w1;\n memcpy(&w0, p, 2);\n memcpy(&w1, p + 2, 2);\n int hi = HEXPAIR[w0];\n int lo = HEXPAIR[w1];\n if ((hi | lo) < 0) return -1;\n *out = (unsigned)((hi << 8) | lo);\n return 0;\n}"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 51+ // HEXPAIR[w], where w = p[0] | (p[1] << 8) (i.e. a native-endian 16-bit load 52+ // of two consecutive input bytes), gives the combined byte value 53+ // (hexval(p[0]) << 4) | hexval(p[1]) if both are hex digits, else -1. This 54+ // turns "decode 2 hex digits" into a single table lookup instead of two 55+ // lookups + an OR + a shift. Built once by a constructor (compile-time 56+ // setup is not counted; only per-call work is). 57+ static int16_t HEXPAIR[65536]; 59+ __attribute__((constructor)) 60+ static void init_hexpair(void) { 61+ for (int b1 = 0; b1 < 256; b1++) { 62+ int h1 = HEXVAL[b1]; 63+ for (int b0 = 0; b0 < 256; b0++) { 64+ int h0 = HEXVAL[b0]; 65+ int idx = b0 | (b1 << 8); 66+ HEXPAIR[idx] = (int16_t)((h0 < 0 || h1 < 0) ? -1 : ((h0 << 4) | h1)); 67+ } 68+ } 69+ } 52- int h0 = HEXVAL[p[0]], h1 = HEXVAL[p[1]], h2 = HEXVAL[p[2]], h3 = HEXVAL[p[3]]; 53- if ((h0 | h1 | h2 | h3) < 0) return -1; 54- *out = (unsigned)((h0 << 12) | (h1 << 8) | (h2 << 4) | h3); 72+ uint16_t w0, w1; 73+ memcpy(&w0, p, 2); 74+ memcpy(&w1, p + 2, 2); 75+ int hi = HEXPAIR[w0]; 76+ int lo = HEXPAIR[w1]; 77+ if ((hi | lo) < 0) return -1; 78+ *out = (unsigned)((hi << 8) | lo); Context after edit (lines 48-83): 48│ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 49│ }; 50│ 51│ // HEXPAIR[w], where w = p[0] | (p[1] << 8) (i.e. a native-endian 16-bit load 52│ // of two consecutive input bytes), gives the combined byte value 53│ // (hexval(p[0]) << 4) | hexval(p[1]) if both are hex digits, else -1. This 54│ // turns "decode 2 hex digits" into a single table lookup instead of two 55│ // lookups + an OR + a shift. Built once by a constructor (compile-time 56│ // setup is not counted; only per-call work is). 57│ static int16_t HEXPAIR[65536]; 58│ 59│ __attribute__((constructor)) 60│ static void init_hexpair(void) { 61│ for (int b1 = 0; b1 < 256; b1++) { 62│ int h1 = HEXVAL[b1]; 63│ for (int b0 = 0; b0 < 256; b0++) { 64│ int h0 = HEXVAL[b0]; 65│ int idx = b0 | (b1 << 8); 66│ HEXPAIR[idx] = (int16_t)((h0 < 0 || h1 < 0) ? -1 : ((h0 << 4) | h1)); 67│ } 68│ } 69│ } 70│ 71│ static inline int parse_hex4(const uint8_t *p, unsigned *out) { 72│ uint16_t w0, w1; 73│ memcpy(&w0, p, 2); 74│ memcpy(&w1, p + 2, 2); 75│ int hi = HEXPAIR[w0]; 76│ int lo = HEXPAIR[w1]; 77│ if ((hi | lo) < 0) return -1; 78│ *out = (unsigned)((hi << 8) | lo); 79│ return 0; 80│ } 81│ 82│ // Scans forward from `i` copying plain (non-special) bytes to `out` until 83│ // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10"}

build 1.4s verify 0.8s PASS measure 1.1s 25,820,229 instructions (given: 53,319,968) SCORE +1.0462 (2.065x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 1 2 3; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +1.0596 (2.084x) SCORE +1.0360 (2.051x) SCORE +1.0721 (2.102x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --seed 42 --quiet 2>&1\ncallgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null > /tmp/ann2.txt\nsed -n '/User-annotated source/,/following files/p' /tmp/ann2.txt"}

SCORE +1.0573 (2.081x) -- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 67 ---------------------------------------- . } . } . } . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { . uint16_t w0, w1; . memcpy(&w0, p, 2); . memcpy(&w1, p + 2, 2); 110,786 ( 2.34%) int hi = HEXPAIR[w0]; 78,504 ( 1.66%) int lo = HEXPAIR[w1]; 117,756 ( 2.48%) if ((hi | lo) < 0) return -1; 110,786 ( 2.34%) *out = (unsigned)((hi << 8) | lo); . return 0; . } . . // Scans forward from `i` copying plain (non-special) bytes to `out` until . // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns . // the new i; the caller adds (new_i - old_i) to its own output cursor. . typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); . . static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 4,303 ( 0.09%) while (i < in_len) { 1,514 ( 0.03%) uint8_t c = in[i]; 9,084 ( 0.19%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 2,314 ( 0.05%) out[i - start] = c; 1,400 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,317 ( 0.03%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 12,984 ( 0.27%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,716 ( 0.16%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,175 ( 0.11%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 9,792 ( 0.21%) static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 10,944 ( 0.23%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,765 ( 0.08%) memcpy(out + (i - start), &w, 8); 3,858 ( 0.08%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,634 ( 0.06%) if (special) { 1,446 ( 0.03%) int bit = __builtin_ctzll(special); 1,446 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_copy_scalar(in, i, in_len, out + (i - start)); 9,792 ( 0.21%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . . __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m512i lo = _mm512_set1_epi8(0x20); -- line 134 ---------------------------------------- -- line 155 ---------------------------------------- . . __attribute__((target("avx2"))) . static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m256i qt = _mm256_set1_epi8(0x22); . __m256i bs = _mm256_set1_epi8(0x5C); . __m256i bias = _mm256_set1_epi8((char)0x80); . __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 298,613 ( 6.30%) while (i + 32 <= in_len) { . __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); . _mm256_storeu_si256((__m256i *)(out + (i - start)), v); . __m256i vb = _mm256_sub_epi8(v, bias); . __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 . __m256i eqq = _mm256_cmpeq_epi8(v, qt); . __m256i eqb = _mm256_cmpeq_epi8(v, bs); . __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); . unsigned mask = (unsigned)_mm256_movemask_epi8(special); 187,005 ( 3.94%) if (mask) { 129,459 ( 2.73%) return i + (size_t)__builtin_ctz(mask); . } . i += 32; . } 3,672 ( 0.08%) return scan_copy_swar(in, i, in_len, out + (i - start)); 89,484 ( 1.89%) => submission/solve.c:scan_copy_swar (1,224x) 43,153 ( 0.91%) } . #endif . . static scan_copy_fn g_scan_copy = scan_copy_swar; . . __attribute__((constructor)) . static void select_scan_impl(void) { . #if defined(__x86_64__) || defined(__i386__) . __builtin_cpu_init(); -- line 186 ---------------------------------------- -- line 192 ---------------------------------------- . if (__builtin_cpu_supports("avx2")) { . g_scan_copy = scan_copy_avx2; . return; . } . #endif . g_scan_copy = scan_copy_swar; . } . 6,600 ( 0.14%) size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { 1,200 ( 0.03%) size_t i = 0, o = 0; 89,180 ( 1.88%) while (i < in_len) { . size_t start = i; 221,885 ( 4.68%) i = g_scan_copy(in, i, in_len, out + o); 1,844,925 (38.90%) => /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_copy_avx2 (44,377x) 133,131 ( 2.81%) o += i - start; . 88,754 ( 1.87%) if (i >= in_len) break; . . uint8_t c = in[i]; 87,980 ( 1.86%) if (c != 0x5C) return INVALID; // control byte or bare '"' . . // Backslash escape. 131,970 ( 2.78%) if (i + 1 >= in_len) return INVALID; 43,990 ( 0.93%) uint8_t e = in[i + 1]; 472,708 ( 9.97%) switch (e) { 56,260 ( 1.19%) case '"': out[o++] = '"'; i += 2; continue; 6,080 ( 0.13%) case '\\': out[o++] = '\\'; i += 2; continue; 6,316 ( 0.13%) case '/': out[o++] = '/'; i += 2; continue; 5,812 ( 0.12%) case 'b': out[o++] = '\b'; i += 2; continue; 5,552 ( 0.12%) case 'f': out[o++] = '\f'; i += 2; continue; 5,552 ( 0.12%) case 'n': out[o++] = '\n'; i += 2; continue; 6,072 ( 0.13%) case 'r': out[o++] = '\r'; i += 2; continue; 5,812 ( 0.12%) case 't': out[o++] = '\t'; i += 2; continue; . case 'u': break; . default: return INVALID; . } . // \uXXXX 96,846 ( 2.04%) if (i + 6 > in_len) return INVALID; . unsigned cu; 32,282 ( 0.68%) if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; . i += 6; . unsigned cp; 96,846 ( 2.04%) if (cu >= 0xD800 && cu <= 0xDBFF) { 48,790 ( 1.03%) if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') . return INVALID; . unsigned lo_cu; 6,970 ( 0.15%) if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; 20,910 ( 0.44%) if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; . i += 6; 13,940 ( 0.29%) cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 75,936 ( 1.60%) } else if (cu >= 0xDC00 && cu <= 0xDFFF) { . return INVALID; . } else { . cp = cu; . } . // Emit UTF-8. 50,624 ( 1.07%) if (cp < 0x80) { 108 ( 0.00%) out[o++] = (uint8_t)cp; 50,516 ( 1.07%) } else if (cp < 0x800) { 52,060 ( 1.10%) out[o++] = (uint8_t)(0xC0 | (cp >> 6)); 28,346 ( 0.60%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 48,972 ( 1.03%) } else if (cp < 0x10000) { 97,944 ( 2.07%) out[o++] = (uint8_t)(0xE0 | (cp >> 12)); . out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 122,430 ( 2.58%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } else { 27,880 ( 0.59%) out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 60,108 ( 1.27%) out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 132,794 ( 2.80%) out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 34,850 ( 0.73%) out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); . } . } 426 ( 0.01%) return o; 5,400 ( 0.11%) } -------------------------------------------------------------------------------- -- Auto-annotated source: /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h -------------------------------------------------------------------------------- Ir -- line 225 ---------------------------------------- . ((__m256i) __builtin_ia32_pblendw256 ((__v16hi)(__m256i)(X), \ . (__v16hi)(__m256i)(Y), (int)(M))) . #endif . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi8 (__m256i __A, __m256i __B) . { 390,932 ( 8.24%) return (__m256i) ((__v32qi)__A == (__v32qi)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpeq_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A == (__v16hi)__B); . } -- line 241 ---------------------------------------- -- line 253 ---------------------------------------- . { . return (__m256i) ((__v4di)__A == (__v4di)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi8 (__m256i __A, __m256i __B) . { 195,466 ( 4.12%) return (__m256i) ((__v32qs)__A > (__v32qs)__B); . } . . extern __inline __m256i . __attribute__ ((__gnu_inline__, __always_inline__, __artificial__)) . _mm256_cmpgt_epi16 (__m256i __A, __m256i __B) . { . return (__m256i) ((__v16hi)__A > (__v16hi)__B); . } -- line 269 ---------------------------------------- -- line 427 ---------------------------------------- . { . return (__m256i)__builtin_ia32_pminud256 ((__v8si)__A, (__v8si)__B); . } . . extern __inline int . __attribute__ ((__gnu_inline__, __always_inlin ... [3950 characters truncated for page size]

{"command": "/tmp/checkwhich\necho \"--- under valgrind (memcheck) ---\"\nvalgrind /tmp/checkwhich 2>&1 | grep chosen\necho \"--- under callgrind ---\"\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/checkwhich 2>&1 | grep chosen"}

f=32768 bw=2097152 vl=1048576 avx2=1024 chosen=avx512 --- under valgrind (memcheck) --- f=0 bw=0 vl=0 avx2=1024 chosen=avx2 --- under callgrind --- f=0 bw=0 vl=0 avx2=1024 chosen=avx2 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | sed -n '1,90p'"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002d40 <json_unescape>: 2d40: 48 85 f6 test rsi,rsi 2d43: 0f 84 ca 02 00 00 je 3013 <json_unescape+0x2d3> 2d49: 41 57 push r15 2d4b: 49 89 ff mov r15,rdi 2d4e: 41 56 push r14 2d50: 49 89 d6 mov r14,rdx 2d53: 41 55 push r13 2d55: 45 31 ed xor r13d,r13d 2d58: 41 54 push r12 2d5a: 49 89 f4 mov r12,rsi 2d5d: 55 push rbp 2d5e: 48 8d 2d bb 12 00 00 lea rbp,[rip+0x12bb] # 4020 <_IO_stdin_used+0x20> 2d65: 53 push rbx 2d66: 31 db xor ebx,ebx 2d68: 48 83 ec 08 sub rsp,0x8 2d6c: 0f 1f 40 00 nop DWORD PTR [rax+0x0] 2d70: 49 8d 0c 1e lea rcx,[r14+rbx*1] 2d74: 4c 89 e2 mov rdx,r12 2d77: 4c 89 ee mov rsi,r13 2d7a: 4c 89 ff mov rdi,r15 2d7d: ff 15 dd 32 00 00 call QWORD PTR [rip+0x32dd] # 6060 <g_scan_copy> 2d83: 48 01 c3 add rbx,rax 2d86: 4c 29 eb sub rbx,r13 2d89: 48 89 d9 mov rcx,rbx 2d8c: 4c 39 e0 cmp rax,r12 2d8f: 73 46 jae 2dd7 <json_unescape+0x97> 2d91: 41 80 3c 07 5c cmp BYTE PTR [r15+rax*1],0x5c 2d96: 75 38 jne 2dd0 <json_unescape+0x90> 2d98: 48 8d 50 01 lea rdx,[rax+0x1] 2d9c: 4c 39 e2 cmp rdx,r12 2d9f: 73 2f jae 2dd0 <json_unescape+0x90> 2da1: 41 0f b6 54 07 01 movzx edx,BYTE PTR [r15+rax*1+0x1] 2da7: 80 fa 75 cmp dl,0x75 2daa: 77 24 ja 2dd0 <json_unescape+0x90> 2dac: 80 fa 5b cmp dl,0x5b 2daf: 0f 86 9b 01 00 00 jbe 2f50 <json_unescape+0x210> 2db5: 83 ea 5c sub edx,0x5c 2db8: 80 fa 19 cmp dl,0x19 2dbb: 77 13 ja 2dd0 <json_unescape+0x90> 2dbd: 0f b6 d2 movzx edx,dl 2dc0: 48 63 54 95 00 movsxd rdx,DWORD PTR [rbp+rdx*4+0x0] 2dc5: 48 01 ea add rdx,rbp 2dc8: ff e2 jmp rdx 2dca: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0] 2dd0: 48 c7 c1 ff ff ff ff mov rcx,0xffffffffffffffff 2dd7: 48 83 c4 08 add rsp,0x8 2ddb: 48 89 c8 mov rax,rcx 2dde: 5b pop rbx 2ddf: 5d pop rbp 2de0: 41 5c pop r12 2de2: 41 5d pop r13 2de4: 41 5e pop r14 2de6: 41 5f pop r15 2de8: c3 ret 2de9: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0] 2df0: 4c 8d 68 06 lea r13,[rax+0x6] 2df4: 4d 39 ec cmp r12,r13 2df7: 72 d7 jb 2dd0 <json_unescape+0x90> 2df9: 49 8d 74 07 02 lea rsi,[r15+rax*1+0x2] 2dfe: 48 8d 3d 9b 32 00 00 lea rdi,[rip+0x329b] # 60a0 <HEXPAIR> 2e05: 0f b7 16 movzx edx,WORD PTR [rsi] 2e08: 0f b7 76 02 movzx esi,WORD PTR [rsi+0x2] 2e0c: 0f bf 14 57 movsx edx,WORD PTR [rdi+rdx*2] 2e10: 0f bf 34 77 movsx esi,WORD PTR [rdi+rsi*2] 2e14: 89 d3 mov ebx,edx 2e16: 66 09 f3 or bx,si 2e19: 78 b5 js 2dd0 <json_unescape+0x90> 2e1b: c1 e2 08 shl edx,0x8 2e1e: 09 f2 or edx,esi 2e20: 44 8d 82 00 28 ff ff lea r8d,[rdx-0xd800] 2e27: 89 d6 mov esi,edx 2e29: 41 81 f8 ff 03 00 00 cmp r8d,0x3ff 2e30: 0f 87 52 01 00 00 ja 2f88 <json_unescape+0x248> 2e36: 4c 8d 68 0c lea r13,[rax+0xc] 2e3a: 4d 39 ec cmp r12,r13 2e3d: 72 91 jb 2dd0 <json_unescape+0x90> 2e3f: 41 80 7c 07 06 5c cmp BYTE PTR [r15+rax*1+0x6],0x5c 2e45: 75 89 jne 2dd0 <json_unescape+0x90> 2e47: 41 80 7c 07 07 75 cmp BYTE PTR [r15+rax*1+0x7],0x75 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | sed -n '90,180p'"}

2e47: 41 80 7c 07 07 75 cmp BYTE PTR [r15+rax*1+0x7],0x75 2e4d: 75 81 jne 2dd0 <json_unescape+0x90> 2e4f: 49 8d 54 07 08 lea rdx,[r15+rax*1+0x8] 2e54: 0f b7 02 movzx eax,WORD PTR [rdx] 2e57: 0f b7 52 02 movzx edx,WORD PTR [rdx+0x2] 2e5b: 0f bf 04 47 movsx eax,WORD PTR [rdi+rax*2] 2e5f: 0f bf 14 57 movsx edx,WORD PTR [rdi+rdx*2] 2e63: 89 c7 mov edi,eax 2e65: 66 09 d7 or di,dx 2e68: 0f 88 62 ff ff ff js 2dd0 <json_unescape+0x90> 2e6e: c1 e0 08 shl eax,0x8 2e71: 09 d0 or eax,edx 2e73: 8d 90 00 24 ff ff lea edx,[rax-0xdc00] 2e79: 81 fa ff 03 00 00 cmp edx,0x3ff 2e7f: 0f 87 4b ff ff ff ja 2dd0 <json_unescape+0x90> 2e85: 41 c1 e0 0a shl r8d,0xa 2e89: 42 8d b4 00 00 24 00 lea esi,[rax+r8*1+0x2400] 2e90: 00 2e91: 89 f0 mov eax,esi 2e93: 48 8d 59 04 lea rbx,[rcx+0x4] 2e97: c1 e8 12 shr eax,0x12 2e9a: 83 c8 f0 or eax,0xfffffff0 2e9d: 41 88 04 0e mov BYTE PTR [r14+rcx*1],al 2ea1: 89 f0 mov eax,esi 2ea3: c1 e8 0c shr eax,0xc 2ea6: 83 e0 3f and eax,0x3f 2ea9: 83 c8 80 or eax,0xffffff80 2eac: 41 88 44 0e 01 mov BYTE PTR [r14+rcx*1+0x1],al 2eb1: 89 f0 mov eax,esi 2eb3: 83 e6 3f and esi,0x3f 2eb6: c1 e8 06 shr eax,0x6 2eb9: 83 ce 80 or esi,0xffffff80 2ebc: 83 e0 3f and eax,0x3f 2ebf: 41 88 74 0e 03 mov BYTE PTR [r14+rcx*1+0x3],sil 2ec4: 83 c8 80 or eax,0xffffff80 2ec7: 41 88 44 0e 02 mov BYTE PTR [r14+rcx*1+0x2],al 2ecc: eb 12 jmp 2ee0 <json_unescape+0x1a0> 2ece: 66 90 xchg ax,ax 2ed0: 41 c6 04 0e 09 mov BYTE PTR [r14+rcx*1],0x9 2ed5: 48 8d 5b 01 lea rbx,[rbx+0x1] 2ed9: 4c 8d 68 02 lea r13,[rax+0x2] 2edd: 0f 1f 00 nop DWORD PTR [rax] 2ee0: 4d 39 e5 cmp r13,r12 2ee3: 0f 82 87 fe ff ff jb 2d70 <json_unescape+0x30> 2ee9: 48 89 d9 mov rcx,rbx 2eec: e9 e6 fe ff ff jmp 2dd7 <json_unescape+0x97> 2ef1: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0] 2ef8: 41 c6 04 0e 0d mov BYTE PTR [r14+rcx*1],0xd 2efd: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f01: 4c 8d 68 02 lea r13,[rax+0x2] 2f05: eb d9 jmp 2ee0 <json_unescape+0x1a0> 2f07: 66 0f 1f 84 00 00 00 nop WORD PTR [rax+rax*1+0x0] 2f0e: 00 00 2f10: 41 c6 04 0e 0a mov BYTE PTR [r14+rcx*1],0xa 2f15: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f19: 4c 8d 68 02 lea r13,[rax+0x2] 2f1d: eb c1 jmp 2ee0 <json_unescape+0x1a0> 2f1f: 90 nop 2f20: 41 c6 04 0e 0c mov BYTE PTR [r14+rcx*1],0xc 2f25: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f29: 4c 8d 68 02 lea r13,[rax+0x2] 2f2d: eb b1 jmp 2ee0 <json_unescape+0x1a0> 2f2f: 90 nop 2f30: 41 c6 04 0e 08 mov BYTE PTR [r14+rcx*1],0x8 2f35: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f39: 4c 8d 68 02 lea r13,[rax+0x2] 2f3d: eb a1 jmp 2ee0 <json_unescape+0x1a0> 2f3f: 90 nop 2f40: 41 c6 04 0e 5c mov BYTE PTR [r14+rcx*1],0x5c 2f45: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f49: 4c 8d 68 02 lea r13,[rax+0x2] 2f4d: eb 91 jmp 2ee0 <json_unescape+0x1a0> 2f4f: 90 nop 2f50: 80 fa 22 cmp dl,0x22 2f53: 74 1b je 2f70 <json_unescape+0x230> 2f55: 80 fa 2f cmp dl,0x2f 2f58: 0f 85 72 fe ff ff jne 2dd0 <json_unescape+0x90> 2f5e: 41 c6 04 0e 2f mov BYTE PTR [r14+rcx*1],0x2f 2f63: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f67: 4c 8d 68 02 lea r13,[rax+0x2] 2f6b: e9 70 ff ff ff jmp 2ee0 <json_unescape+0x1a0> 2f70: 41 c6 04 0e 22 mov BYTE PTR [r14+rcx*1],0x22 2f75: 48 8d 5b 01 lea rbx,[rbx+0x1] 2f79: 4c 8d 68 02 lea r13,[rax+0x2] 2f7d: e9 5e ff ff ff jmp 2ee0 <json_unescape+0x1a0> 2f82: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0] 2f88: 8d 82 00 24 ff ff lea eax,[rdx-0xdc00] 2f8e: 3d ff 03 00 00 cmp eax,0x3ff 2f93: 0f 86 37 fe ff ff jbe 2dd0 <json_unescape+0x90> 2f99: 4d 8d 04 0e lea r8,[r14+rcx*1] 2f9d: 48 8d 59 01 lea rbx,[rcx+0x1] --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nimport struct\nwith open('.build/corpus_42.bin','rb') as f:\n data=f.read()\noff=0\nn=0\nesc=0\ntot=0\nuesc=0\nsurresc=0\nwhile off+4<=len(data):\n ln=struct.unpack('<I',data[off:off+4])[0]\n off+=4\n rec=data[off:off+ln]\n off+=ln\n tot+=ln\n n+=1\n esc+=rec.count(b'\\\\\\\\')\n uesc+=rec.count(b'\\\\\\\\u')\nprint(n,tot,esc,uesc)\n\""}

600 1066619 52480 39261 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nimport struct\nwith open('.build/corpus_42.bin','rb') as f:\n data=f.read()\noff=0\nn=0\ntot=0\nrunlen_total=0\nruns=0\nwhile off+4<=len(data):\n ln=struct.unpack('<I',data[off:off+4])[0]\n off+=4\n rec=data[off:off+ln]\n off+=ln\n tot+=ln\n n+=1\n i=0\n cur=0\n while i<len(rec):\n c=rec[i]\n if c<0x20 or c==0x22 or c==0x5c:\n runs+=1\n runlen_total+=cur\n cur=0\n if c==0x5c:\n # skip escape roughly\n i+=2\n continue\n else:\n cur+=1\n i+=1\n runlen_total+=cur\n runs+=1\nprint('avg run len', runlen_total/runs, 'runs',runs)\n\""}

avg run len 18.71022110162917 runs 51560 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=scan_copy_avx2 -M intel 2>/dev/null"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002be0 <scan_copy_avx2>: 2be0: b8 5c 5c 5c 5c mov eax,0x5c5c5c5c 2be5: c5 f9 6e f0 vmovd xmm6,eax 2be9: b8 22 22 22 22 mov eax,0x22222222 2bee: c5 f9 6e e8 vmovd xmm5,eax 2bf2: b8 80 80 80 80 mov eax,0x80808080 2bf7: c4 e2 7d 58 f6 vpbroadcastd ymm6,xmm6 2bfc: c5 f9 6e e0 vmovd xmm4,eax 2c00: b8 a0 a0 a0 a0 mov eax,0xa0a0a0a0 2c05: c4 e2 7d 58 ed vpbroadcastd ymm5,xmm5 2c0a: c5 f9 6e d8 vmovd xmm3,eax 2c0e: c4 e2 7d 58 e4 vpbroadcastd ymm4,xmm4 2c13: c4 e2 7d 58 db vpbroadcastd ymm3,xmm3 2c18: eb 55 jmp 2c6f <scan_copy_avx2+0x8f> 2c1a: 0f 1f 44 00 00 nop DWORD PTR [rax+rax*1+0x0] 2c1f: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2c26: 00 00 00 00 2c2a: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2c31: 00 00 00 00 2c35: 66 66 2e 0f 1f 84 00 data16 cs nop WORD PTR [rax+rax*1+0x0] 2c3c: 00 00 00 00 2c40: c5 fe 6f 44 37 e0 vmovdqu ymm0,YMMWORD PTR [rdi+rsi*1-0x20] 2c46: 48 83 c1 20 add rcx,0x20 2c4a: c5 fd 74 ce vpcmpeqb ymm1,ymm0,ymm6 2c4e: c5 fd 74 d5 vpcmpeqb ymm2,ymm0,ymm5 2c52: c5 fe 7f 41 e0 vmovdqu YMMWORD PTR [rcx-0x20],ymm0 2c57: c5 fd fc c4 vpaddb ymm0,ymm0,ymm4 2c5b: c5 e5 64 c0 vpcmpgtb ymm0,ymm3,ymm0 2c5f: c5 f5 eb ca vpor ymm1,ymm1,ymm2 2c63: c5 f5 eb c0 vpor ymm0,ymm1,ymm0 2c67: c5 fd d7 c0 vpmovmskb eax,ymm0 2c6b: 85 c0 test eax,eax 2c6d: 75 21 jne 2c90 <scan_copy_avx2+0xb0> 2c6f: 49 89 f0 mov r8,rsi 2c72: 48 83 c6 20 add rsi,0x20 2c76: 48 39 f2 cmp rdx,rsi 2c79: 73 c5 jae 2c40 <scan_copy_avx2+0x60> 2c7b: 4c 89 c6 mov rsi,r8 2c7e: c5 f8 77 vzeroupper 2c81: e9 3a fe ff ff jmp 2ac0 <scan_copy_swar> 2c86: 66 2e 0f 1f 84 00 00 cs nop WORD PTR [rax+rax*1+0x0] 2c8d: 00 00 00 2c90: f3 0f bc c0 tzcnt eax,eax 2c94: 4c 01 c0 add rax,r8 2c97: c5 f8 77 vzeroupper 2c9a: c3 ret Disassembly of section .fini: --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && sed -n '/size_t json_unescape/,/^}/p' submission/solve.c | head -100"}

size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { size_t i = 0, o = 0; while (i < in_len) { size_t start = i; i = g_scan_copy(in, i, in_len, out + o); o += i - start; if (i >= in_len) break; uint8_t c = in[i]; if (c != 0x5C) return INVALID; // control byte or bare '"' // Backslash escape. if (i + 1 >= in_len) return INVALID; uint8_t e = in[i + 1]; switch (e) { case '"': out[o++] = '"'; i += 2; continue; case '\\': out[o++] = '\\'; i += 2; continue; case '/': out[o++] = '/'; i += 2; continue; case 'b': out[o++] = '\b'; i += 2; continue; case 'f': out[o++] = '\f'; i += 2; continue; case 'n': out[o++] = '\n'; i += 2; continue; case 'r': out[o++] = '\r'; i += 2; continue; case 't': out[o++] = '\t'; i += 2; continue; case 'u': break; default: return INVALID; } // \uXXXX if (i + 6 > in_len) return INVALID; unsigned cu; if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; i += 6; unsigned cp; if (cu >= 0xD800 && cu <= 0xDBFF) { if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') return INVALID; unsigned lo_cu; if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; i += 6; cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); } else if (cu >= 0xDC00 && cu <= 0xDFFF) { return INVALID; } else { cp = cu; } // Emit UTF-8. if (cp < 0x80) { out[o++] = (uint8_t)cp; } else if (cp < 0x800) { out[o++] = (uint8_t)(0xC0 | (cp >> 6)); out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); } else if (cp < 0x10000) { out[o++] = (uint8_t)(0xE0 | (cp >> 12)); out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); } else { 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)); } } return o; } --- Command finished with exit code: 0 ---

{"command": "python3 -c \"\nvals=[50624,108,50516,52060,28346,48972,97944,122430,27880,60108,132794,34850]\nprint(sum(vals))\n\""}

706632 --- Command finished with exit code: 0 ---

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "old_string": " // \\uXXXX\n if (i + 6 > in_len) return INVALID;\n unsigned cu;\n if (parse_hex4(in + i + 2, &cu) < 0) return INVALID;\n i += 6;\n unsigned cp;\n if (cu >= 0xD800 && cu <= 0xDBFF) {\n if (i + 6 > in_len || in[i] != '\\\\' || in[i + 1] != 'u')\n return INVALID;\n unsigned lo_cu;\n if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID;\n if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID;\n i += 6;\n cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00);\n } else if (cu >= 0xDC00 && cu <= 0xDFFF) {\n return INVALID;\n } else {\n cp = cu;\n }\n // Emit UTF-8.\n if (cp < 0x80) {\n out[o++] = (uint8_t)cp;\n } else if (cp < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (cp >> 6));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n } else if (cp < 0x10000) {\n out[o++] = (uint8_t)(0xE0 | (cp >> 12));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n } else {\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n }\n }\n return o;\n}", "new_string": " // \\uXXXX\n if (i + 6 > in_len) return INVALID;\n unsigned cu;\n if (parse_hex4(in + i + 2, &cu) < 0) return INVALID;\n i += 6;\n if (cu >= 0xD800 && cu <= 0xDBFF) {\n if (i + 6 > in_len || in[i] != '\\\\' || in[i + 1] != 'u')\n return INVALID;\n unsigned lo_cu;\n if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID;\n if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID;\n i += 6;\n unsigned cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00);\n // Surrogate pairs always decode to a supplementary code point\n // (>= 0x10000), which is always exactly 4 UTF-8 bytes: no need\n // to re-check the length thresholds.\n out[o++] = (uint8_t)(0xF0 | (cp >> 18));\n out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F));\n out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cp & 0x3F));\n continue;\n } else if (cu >= 0xDC00 && cu <= 0xDFFF) {\n return INVALID;\n }\n // A lone \\uXXXX (not part of a surrogate pair) is always a BMP code\n // point outside the surrogate range, i.e. < 0x10000: only 3 length\n // classes are possible.\n if (cu < 0x80) {\n out[o++] = (uint8_t)cu;\n } else if (cu < 0x800) {\n out[o++] = (uint8_t)(0xC0 | (cu >> 6));\n out[o++] = (uint8_t)(0x80 | (cu & 0x3F));\n } else {\n out[o++] = (uint8_t)(0xE0 | (cu >> 12));\n out[o++] = (uint8_t)(0x80 | ((cu >> 6) & 0x3F));\n out[o++] = (uint8_t)(0x80 | (cu & 0x3F));\n }\n }\n return o;\n}"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 232- unsigned cp; 240- cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 239+ unsigned cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 240+ // Surrogate pairs always decode to a supplementary code point 241+ // (>= 0x10000), which is always exactly 4 UTF-8 bytes: no need 242+ // to re-check the length thresholds. 243+ out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 244+ out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 245+ out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 246+ out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 247+ continue; 243- } else { 244- cp = cu; 246- // Emit UTF-8. 247- if (cp < 0x80) { 248- out[o++] = (uint8_t)cp; 249- } else if (cp < 0x800) { 250- out[o++] = (uint8_t)(0xC0 | (cp >> 6)); 251- out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 252- } else if (cp < 0x10000) { 253- out[o++] = (uint8_t)(0xE0 | (cp >> 12)); 254- out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 255- out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 251+ // A lone \uXXXX (not part of a surrogate pair) is always a BMP code 252+ // point outside the surrogate range, i.e. < 0x10000: only 3 length 253+ // classes are possible. 254+ if (cu < 0x80) { 255+ out[o++] = (uint8_t)cu; 256+ } else if (cu < 0x800) { 257+ out[o++] = (uint8_t)(0xC0 | (cu >> 6)); 258+ out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); 257- out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 258- out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 259- out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 260- out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 260+ out[o++] = (uint8_t)(0xE0 | (cu >> 12)); 261+ out[o++] = (uint8_t)(0x80 | ((cu >> 6) & 0x3F)); 262+ out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); Context after edit (lines 224-266): 224│ case 'u': break; 225│ default: return INVALID; 226│ } 227│ // \uXXXX 228│ if (i + 6 > in_len) return INVALID; 229│ unsigned cu; 230│ if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; 231│ i += 6; 232│ if (cu >= 0xD800 && cu <= 0xDBFF) { 233│ if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') 234│ return INVALID; 235│ unsigned lo_cu; 236│ if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; 237│ if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; 238│ i += 6; 239│ unsigned cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 240│ // Surrogate pairs always decode to a supplementary code point 241│ // (>= 0x10000), which is always exactly 4 UTF-8 bytes: no need 242│ // to re-check the length thresholds. 243│ out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 244│ out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 245│ out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 246│ out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 247│ continue; 248│ } else if (cu >= 0xDC00 && cu <= 0xDFFF) { 249│ return INVALID; 250│ } 251│ // A lone \uXXXX (not part of a surrogate pair) is always a BMP code 252│ // point outside the surrogate range, i.e. < 0x10000: only 3 length 253│ // classes are possible. 254│ if (cu < 0x80) { 255│ out[o++] = (uint8_t)cu; 256│ } else if (cu < 0x800) { 257│ out[o++] = (uint8_t)(0xC0 | (cu >> 6)); 258│ out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); 259│ } else { 260│ out[o++] = (uint8_t)(0xE0 | (cu >> 12)); 261│ out[o++] = (uint8_t)(0x80 | ((cu >> 6) & 0x3F)); 262│ out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); 263│ } 264│ } 265│ return o; 266│ }

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10"}

build 1.4s verify 0.8s PASS measure 1.1s 24,133,346 instructions (given: 51,488,656) SCORE +1.0932 (2.134x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 1 2 3; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +1.0946 (2.136x) SCORE +1.0707 (2.100x) SCORE +1.1068 (2.154x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && grep -n \"switch (e)\" submission/solve.c"}

215: switch (e) { --- Command finished with exit code: 0 ---

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "old_string": "static inline int parse_hex4(const uint8_t *p, unsigned *out) {", "new_string": "// Decoded byte for each simple \\X escape, or -1 if X is not a valid simple\n// escape character. 'u' (which needs separate \\uXXXX handling) is also -1\n// here and is special-cased by the caller before consulting this table.\nstatic const int16_t SIMPLE_ESCAPE[256] = {\n [0 ... 255] = -1,\n ['\"'] = '\"',\n ['\\\\'] = '\\\\',\n ['/'] = '/',\n ['b'] = '\\b',\n ['f'] = '\\f',\n ['n'] = '\\n',\n ['r'] = '\\r',\n ['t'] = '\\t',\n};\n\nstatic inline int parse_hex4(const uint8_t *p, unsigned *out) {"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 71+ // Decoded byte for each simple \X escape, or -1 if X is not a valid simple 72+ // escape character. 'u' (which needs separate \uXXXX handling) is also -1 73+ // here and is special-cased by the caller before consulting this table. 74+ static const int16_t SIMPLE_ESCAPE[256] = { 75+ [0 ... 255] = -1, 76+ ['"'] = '"', 77+ ['\\'] = '\\', 78+ ['/'] = '/', 79+ ['b'] = '\b', 80+ ['f'] = '\f', 81+ ['n'] = '\n', 82+ ['r'] = '\r', 83+ ['t'] = '\t', 84+ }; Context after edit (lines 68-89): 68│ } 69│ } 70│ 71│ // Decoded byte for each simple \X escape, or -1 if X is not a valid simple 72│ // escape character. 'u' (which needs separate \uXXXX handling) is also -1 73│ // here and is special-cased by the caller before consulting this table. 74│ static const int16_t SIMPLE_ESCAPE[256] = { 75│ [0 ... 255] = -1, 76│ ['"'] = '"', 77│ ['\\'] = '\\', 78│ ['/'] = '/', 79│ ['b'] = '\b', 80│ ['f'] = '\f', 81│ ['n'] = '\n', 82│ ['r'] = '\r', 83│ ['t'] = '\t', 84│ }; 85│ 86│ static inline int parse_hex4(const uint8_t *p, unsigned *out) { 87│ uint16_t w0, w1; 88│ memcpy(&w0, p, 2); 89│ memcpy(&w1, p + 2, 2);

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "old_string": " uint8_t e = in[i + 1];\n switch (e) {\n case '\"': out[o++] = '\"'; i += 2; continue;\n case '\\\\': out[o++] = '\\\\'; i += 2; continue;\n case '/': out[o++] = '/'; i += 2; continue;\n case 'b': out[o++] = '\\b'; i += 2; continue;\n case 'f': out[o++] = '\\f'; i += 2; continue;\n case 'n': out[o++] = '\\n'; i += 2; continue;\n case 'r': out[o++] = '\\r'; i += 2; continue;\n case 't': out[o++] = '\\t'; i += 2; continue;\n case 'u': break;\n default: return INVALID;\n }", "new_string": " uint8_t e = in[i + 1];\n if (e != 'u') {\n int decoded = SIMPLE_ESCAPE[e];\n if (decoded < 0) return INVALID;\n out[o++] = (uint8_t)decoded;\n i += 2;\n continue;\n }"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 230- switch (e) { 231- case '"': out[o++] = '"'; i += 2; continue; 232- case '\\': out[o++] = '\\'; i += 2; continue; 233- case '/': out[o++] = '/'; i += 2; continue; 234- case 'b': out[o++] = '\b'; i += 2; continue; 235- case 'f': out[o++] = '\f'; i += 2; continue; 236- case 'n': out[o++] = '\n'; i += 2; continue; 237- case 'r': out[o++] = '\r'; i += 2; continue; 238- case 't': out[o++] = '\t'; i += 2; continue; 239- case 'u': break; 240- default: return INVALID; 230+ if (e != 'u') { 231+ int decoded = SIMPLE_ESCAPE[e]; 232+ if (decoded < 0) return INVALID; 233+ out[o++] = (uint8_t)decoded; 234+ i += 2; 235+ continue; Context after edit (lines 226-239): 226│ 227│ // Backslash escape. 228│ if (i + 1 >= in_len) return INVALID; 229│ uint8_t e = in[i + 1]; 230│ if (e != 'u') { 231│ int decoded = SIMPLE_ESCAPE[e]; 232│ if (decoded < 0) return INVALID; 233│ out[o++] = (uint8_t)decoded; 234│ i += 2; 235│ continue; 236│ } 237│ // \uXXXX 238│ if (i + 6 > in_len) return INVALID; 239│ unsigned cu;

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10"}

build 1.4s verify 0.8s PASS measure 1.2s 23,670,841 instructions (given: 53,915,709) SCORE +1.1876 (2.278x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 1 2 3 4; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +1.2059 (2.307x) SCORE +1.1825 (2.270x) SCORE +1.2179 (2.326x) SCORE +1.1979 (2.294x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --seed 42 --quiet 2>&1\ncallgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null > /tmp/ann3.txt\nsed -n '/User-annotated source/,/following files/p' /tmp/ann3.txt | head -150"}

SCORE +1.2022 (2.301x) -- User-annotated source: submission/solve.c -------------------------------------------------------------------------------- Ir -- line 82 ---------------------------------------- . ['r'] = '\r', . ['t'] = '\t', . }; . . static inline int parse_hex4(const uint8_t *p, unsigned *out) { . uint16_t w0, w1; . memcpy(&w0, p, 2); . memcpy(&w1, p + 2, 2); 117,756 ( 2.76%) int hi = HEXPAIR[w0]; 78,504 ( 1.84%) int lo = HEXPAIR[w1]; 117,756 ( 2.76%) if ((hi | lo) < 0) return -1; 78,504 ( 1.84%) *out = (unsigned)((hi << 8) | lo); . return 0; . } . . // Scans forward from `i` copying plain (non-special) bytes to `out` until . // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns . // the new i; the caller adds (new_i - old_i) to its own output cursor. . typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); . . static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 4,303 ( 0.10%) while (i < in_len) { 1,514 ( 0.04%) uint8_t c = in[i]; 9,084 ( 0.21%) if (c < 0x20 || c == 0x22 || c == 0x5C) break; 2,314 ( 0.05%) out[i - start] = c; 1,400 ( 0.03%) i++; . } . return i; . } . . static inline uint64_t load64(const uint8_t *p) { . uint64_t v; 1,317 ( 0.03%) memcpy(&v, p, 8); . return v; . } . static inline uint64_t haszero(uint64_t v) { 12,984 ( 0.30%) return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; . } . static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 7,716 ( 0.18%) return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); . } . static inline uint64_t hasless(uint64_t x, uint8_t n) { 5,175 ( 0.12%) return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; . } . 9,792 ( 0.23%) static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; 10,944 ( 0.26%) while (i + 8 <= in_len) { . uint64_t w = load64(in + i); 3,765 ( 0.09%) memcpy(out + (i - start), &w, 8); 3,858 ( 0.09%) uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 2,634 ( 0.06%) if (special) { 1,446 ( 0.03%) int bit = __builtin_ctzll(special); 1,446 ( 0.03%) return i + (size_t)(bit >> 3); . } . i += 8; . } . return scan_copy_scalar(in, i, in_len, out + (i - start)); 9,792 ( 0.23%) } . . #if defined(__x86_64__) || defined(__i386__) . #include <immintrin.h> . . __attribute__((target("avx512f,avx512bw,avx512vl"))) . static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m512i lo = _mm512_set1_epi8(0x20); -- line 149 ---------------------------------------- -- line 170 ---------------------------------------- . . __attribute__((target("avx2"))) . static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { . size_t start = i; . __m256i qt = _mm256_set1_epi8(0x22); . __m256i bs = _mm256_set1_epi8(0x5C); . __m256i bias = _mm256_set1_epi8((char)0x80); . __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 298,613 ( 6.99%) while (i + 32 <= in_len) { . __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); . _mm256_storeu_si256((__m256i *)(out + (i - start)), v); . __m256i vb = _mm256_sub_epi8(v, bias); . __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 . __m256i eqq = _mm256_cmpeq_epi8(v, qt); . __m256i eqb = _mm256_cmpeq_epi8(v, bs); . __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); . unsigned mask = (unsigned)_mm256_movemask_epi8(special); 187,005 ( 4.38%) if (mask) { 129,459 ( 3.03%) return i + (size_t)__builtin_ctz(mask); . } . i += 32; . } 3,672 ( 0.09%) return scan_copy_swar(in, i, in_len, out + (i - start)); 89,484 ( 2.09%) => submission/solve.c:scan_copy_swar (1,224x) 43,153 ( 1.01%) } . #endif . . static scan_copy_fn g_scan_copy = scan_copy_swar; . . __attribute__((constructor)) . static void select_scan_impl(void) { . #if defined(__x86_64__) || defined(__i386__) . __builtin_cpu_init(); -- line 201 ---------------------------------------- -- line 207 ---------------------------------------- . if (__builtin_cpu_supports("avx2")) { . g_scan_copy = scan_copy_avx2; . return; . } . #endif . g_scan_copy = scan_copy_swar; . } . 6,000 ( 0.14%) size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { 1,200 ( 0.03%) size_t i = 0, o = 0; 89,180 ( 2.09%) while (i < in_len) { . size_t start = i; 221,885 ( 5.19%) i = g_scan_copy(in, i, in_len, out + o); 1,844,925 (43.18%) => /usr/lib/gcc/x86_64-pc-linux-gnu/16/include/avx2intrin.h:scan_copy_avx2 (44,377x) 133,131 ( 3.12%) o += i - start; . 88,754 ( 2.08%) if (i >= in_len) break; . . uint8_t c = in[i]; 87,980 ( 2.06%) if (c != 0x5C) return INVALID; // control byte or bare '"' . . // Backslash escape. 131,970 ( 3.09%) if (i + 1 >= in_len) return INVALID; 43,990 ( 1.03%) uint8_t e = in[i + 1]; 87,980 ( 2.06%) if (e != 'u') { 12,308 ( 0.29%) int decoded = SIMPLE_ESCAPE[e]; 23,416 ( 0.55%) if (decoded < 0) return INVALID; 74,040 ( 1.73%) out[o++] = (uint8_t)decoded; 11,708 ( 0.27%) i += 2; . continue; . } . // \uXXXX 96,846 ( 2.27%) if (i + 6 > in_len) return INVALID; . unsigned cu; 32,282 ( 0.76%) if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; . i += 6; 96,846 ( 2.27%) if (cu >= 0xD800 && cu <= 0xDBFF) { 48,790 ( 1.14%) if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') . return INVALID; . unsigned lo_cu; --- Command finished with exit code: 0 ---

{"command": "cat /proc/cpuinfo | grep -m1 \"model name\""}

model name : unknown --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nimport struct\nwith open('.build/corpus_42.bin','rb') as f:\n data=f.read()\noff=0\nrunlens=[]\nwhile off+4<=len(data):\n ln=struct.unpack('<I',data[off:off+4])[0]\n off+=4\n rec=data[off:off+ln]\n off+=ln\n i=0\n cur=0\n while i<len(rec):\n c=rec[i]\n if c<0x20 or c==0x22 or c==0x5c:\n runlens.append(cur)\n cur=0\n if c==0x5c:\n i+=2\n continue\n else:\n cur+=1\n i+=1\n runlens.append(cur)\nrunlens.sort()\nimport statistics\nprint('n',len(runlens),'mean',statistics.mean(runlens),'median',statistics.median(runlens))\nprint('max',max(runlens))\nprint('sum', sum(runlens))\n# weighted average per byte processed\ntot=sum(runlens)\nbig=sum(r for r in runlens if r>32)\nprint('fraction of bytes in runs > 32:', big/tot)\n\"\n"}

n 51560 mean 18.71022110162917 median 4.0 max 4116 sum 964699 fraction of bytes in runs > 32: 0.648686274164273 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=json_unescape -M intel 2>/dev/null | sed -n '55,75p'"}

2dd6: 48 89 c8 mov rax,rcx 2dd9: 5b pop rbx 2dda: 5d pop rbp 2ddb: 41 5c pop r12 2ddd: 41 5d pop r13 2ddf: 41 5e pop r14 2de1: 41 5f pop r15 2de3: c3 ret 2de4: 0f 1f 40 00 nop DWORD PTR [rax+0x0] 2de8: 4c 8d 68 06 lea r13,[rax+0x6] 2dec: 4c 39 eb cmp rbx,r13 2def: 0f 82 eb 00 00 00 jb 2ee0 <json_unescape+0x1a0> 2df5: 49 8d 74 04 02 lea rsi,[r12+rax*1+0x2] 2dfa: 48 8d 3d 9f 22 00 00 lea rdi,[rip+0x229f] # 50a0 <HEXPAIR> 2e01: 0f b7 16 movzx edx,WORD PTR [rsi] 2e04: 0f b7 76 02 movzx esi,WORD PTR [rsi+0x2] 2e08: 0f bf 14 57 movsx edx,WORD PTR [rdi+rdx*2] 2e0c: 0f bf 34 77 movsx esi,WORD PTR [rdi+rsi*2] 2e10: 41 89 d0 mov r8d,edx 2e13: 66 41 09 f0 or r8w,si 2e17: 0f 88 c3 00 00 00 js 2ee0 <json_unescape+0x1a0> --- Command finished with exit code: 0 ---

{"command": "valgrind /tmp/force512 2>&1 | tail -5\necho ---\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/force512 2>&1 | tail -8"}

==2296== ==2296== All heap blocks were freed -- no leaks are possible ==2296== ==2296== For lists of detected and suppressed errors, rerun with: -s ==2296== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- ==2303== Illegal opcode at address 0x40011E0 ==2303== at 0x40011E0: scan.constprop.0 (in /tmp/force512) ==2303== by 0x40010A9: main (in /tmp/force512) ==2303== ==2303== Events : Ir ==2303== Collected : 124011 ==2303== ==2303== I refs: 124,011 --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=memcheck /tmp/force512 2>&1 | tail -10\necho \"====\"\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/force512 2>&1 | tail -10"}

==2320== by 0x40010A9: main (in /tmp/force512) ==2320== ==2320== HEAP SUMMARY: ==2320== in use at exit: 0 bytes in 0 blocks ==2320== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==2320== ==2320== All heap blocks were freed -- no leaks are possible ==2320== ==2320== For lists of detected and suppressed errors, rerun with: -s ==2320== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) ==== ==2325== ==2325== Process terminating with default action of signal 4 (SIGILL): dumping core ==2325== Illegal opcode at address 0x40011E0 ==2325== at 0x40011E0: scan.constprop.0 (in /tmp/force512) ==2325== by 0x40010A9: main (in /tmp/force512) ==2325== ==2325== Events : Ir ==2325== Collected : 124011 ==2325== ==2325== I refs: 124,011 --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=memcheck /tmp/force512 2>&1 | head -20\necho \"RC=$?\""}

==2342== Memcheck, a memory error detector ==2342== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al. ==2342== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info ==2342== Command: /tmp/force512 ==2342== vex amd64->IR: unhandled instruction bytes: 0x62 0xF1 0xFE 0x48 0x6F 0x1F 0xB8 0x20 0x20 0x20 vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0 vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=NONE vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0 ==2342== valgrind: Unrecognised instruction at address 0x40011e0. ==2342== at 0x40011E0: scan.constprop.0 (in /tmp/force512) ==2342== by 0x40010A9: main (in /tmp/force512) ==2342== Your program just tried to execute an instruction that Valgrind ==2342== did not recognise. There are two possible reasons for this. ==2342== 1. Your program has a bug and erroneously jumped to a non-code ==2342== location. If you are running Memcheck and you just saw a ==2342== warning about a bad jump, it's probably your program's fault. ==2342== 2. The instruction is legitimate but Valgrind doesn't handle it, ==2342== i.e. it's Valgrind's fault. If you think this is the case or ==2342== you are not sure, please let us know and we'll try to fix it. RC=0 --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --collect-atstart=yes /tmp/checkwhich 2>&1 | grep chosen"}

f=0 bw=0 vl=0 avx2=1024 chosen=avx2 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/pcmpistri_test.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <stdio.h>\n#include <string.h>\n\n__attribute__((target(\"sse4.2\")))\nint test(const unsigned char *buf) {\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F, // control range\n 0x22, 0x22, // quote\n 0x5C, 0x5C, // backslash\n 0,0,0,0,0,0,0,0,0,0\n );\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n __m128i mask = _mm_cmpistrm(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_BIT_MASK);\n int m = _mm_extract_epi16(mask, 0) & 0xFFFF;\n return m;\n}\nint main(){\n unsigned char buf[16];\n memset(buf,'a',16);\n buf[10]=1;\n printf(\"%d\\n\", test(buf));\n memset(buf,'a',16);\n buf[5]='\"';\n printf(\"%d\\n\", test(buf));\n memset(buf,'a',16);\n buf[3]='\\\\';\n printf(\"%d\\n\", test(buf));\n memset(buf,'a',16);\n printf(\"%d\\n\", test(buf));\n}\nEOF\ngcc -O2 -std=c17 /tmp/pcmpistri_test.c -o /tmp/pcmpistri_test && /tmp/pcmpistri_test"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && python3 -c \"\nimport struct, math\nwith open('.build/corpus_42.bin','rb') as f:\n data=f.read()\noff=0\nrunlens=[]\nwhile off+4<=len(data):\n ln=struct.unpack('<I',data[off:off+4])[0]\n off+=4\n rec=data[off:off+ln]\n off+=ln\n i=0\n cur=0\n while i<len(rec):\n c=rec[i]\n if c<0x20 or c==0x22 or c==0x5c:\n runlens.append(cur)\n cur=0\n if c==0x5c:\n i+=2\n continue\n else:\n cur+=1\n i+=1\n runlens.append(cur)\n\ntotal_iters = sum(max(1, math.ceil(r/32)) if r>0 else 0 for r in runlens)\nprint('runs',len(runlens),'nonzero runs', sum(1 for r in runlens if r>0), 'total_iters', total_iters)\n\"\n"}

runs 51560 nonzero runs 47963 total_iters 67179 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=scan_copy_avx512 -M intel 2>/dev/null"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002ca0 <scan_copy_avx512>: 2ca0: b8 20 20 20 20 mov eax,0x20202020 2ca5: 49 89 f8 mov r8,rdi 2ca8: 48 89 d7 mov rdi,rdx 2cab: 62 f2 7d 48 7c d8 vpbroadcastd zmm3,eax 2cb1: b8 22 22 22 22 mov eax,0x22222222 2cb6: 62 f2 7d 48 7c d0 vpbroadcastd zmm2,eax 2cbc: b8 5c 5c 5c 5c mov eax,0x5c5c5c5c 2cc1: 62 f2 7d 48 7c c8 vpbroadcastd zmm1,eax 2cc7: eb 46 jmp 2d0f <scan_copy_avx512+0x6f> 2cc9: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0] 2cd0: 62 d1 fe 48 6f 44 30 vmovdqu64 zmm0,ZMMWORD PTR [r8+rsi*1-0x40] 2cd7: ff 2cd8: 48 83 c1 40 add rcx,0x40 2cdc: 62 f3 7d 48 3e c3 01 vpcmpltub k0,zmm0,zmm3 2ce3: 62 f3 7d 48 3f ca 00 vpcmpeqb k1,zmm0,zmm2 2cea: 62 f1 fe 48 7f 41 ff vmovdqu64 ZMMWORD PTR [rcx-0x40],zmm0 2cf1: 62 f3 7d 48 3f d1 00 vpcmpeqb k2,zmm0,zmm1 2cf8: c4 e1 fb 93 c1 kmovq rax,k1 2cfd: c4 61 fb 93 d0 kmovq r10,k0 2d02: 4c 09 d0 or rax,r10 2d05: c4 e1 fb 93 d2 kmovq rdx,k2 2d0a: 48 09 d0 or rax,rdx 2d0d: 75 21 jne 2d30 <scan_copy_avx512+0x90> 2d0f: 49 89 f1 mov r9,rsi 2d12: 48 83 c6 40 add rsi,0x40 2d16: 48 39 f7 cmp rdi,rsi 2d19: 73 b5 jae 2cd0 <scan_copy_avx512+0x30> 2d1b: 48 89 fa mov rdx,rdi 2d1e: 4c 89 ce mov rsi,r9 2d21: 4c 89 c7 mov rdi,r8 2d24: c5 f8 77 vzeroupper 2d27: e9 94 fd ff ff jmp 2ac0 <scan_copy_swar> 2d2c: 0f 1f 40 00 nop DWORD PTR [rax+0x0] 2d30: f3 48 0f bc c0 tzcnt rax,rax 2d35: 89 c0 mov eax,eax 2d37: 4c 01 c8 add rax,r9 2d3a: c5 f8 77 vzeroupper 2d3d: c3 ret Disassembly of section .fini: --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/pcmp2.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <stdio.h>\n#include <string.h>\n\n__attribute__((target(\"sse4.2\")))\nstatic int find_special(const unsigned char *buf, int len) {\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0x22, 0x22,\n 0x5C, 0x5C,\n 0,0,0,0,0,0,0,0,0,0\n );\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n return idx;\n}\nint main(){\n unsigned char buf[16];\n memset(buf,'a',16);\n printf(\"all plain: %d\\n\", find_special(buf,16));\n buf[10]=1;\n printf(\"control at 10: %d\\n\", find_special(buf,16));\n memset(buf,'a',16);\n buf[5]='\"';\n printf(\"quote at 5: %d\\n\", find_special(buf,16));\n memset(buf,'a',16);\n buf[3]='\\\\';\n printf(\"backslash at 3: %d\\n\", find_special(buf,16));\n}\nEOF\ngcc -O2 -std=c17 /tmp/pcmp2.c -o /tmp/pcmp2 && /tmp/pcmp2\necho \"--- under valgrind ---\"\nvalgrind /tmp/pcmp2 2>&1 | tail -20"}

all plain: 16 control at 10: 16 quote at 5: 16 backslash at 3: 16 --- under valgrind --- ==2428== warning about a bad jump, it's probably your program's fault. ==2428== 2. The instruction is legitimate but Valgrind doesn't handle it, ==2428== i.e. it's Valgrind's fault. If you think this is the case or ==2428== you are not sure, please let us know and we'll try to fix it. ==2428== Either way, Valgrind will now raise a SIGILL signal which will ==2428== probably kill your program. ==2428== ==2428== Process terminating with default action of signal 4 (SIGILL): dumping core ==2428== Illegal opcode at address 0x4001228 ==2428== at 0x4001228: find_special.constprop.0 (in /tmp/pcmp2) ==2428== by 0x400107B: main (in /tmp/pcmp2) ==2428== ==2428== HEAP SUMMARY: ==2428== in use at exit: 0 bytes in 0 blocks ==2428== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==2428== ==2428== All heap blocks were freed -- no leaks are possible ==2428== ==2428== For lists of detected and suppressed errors, rerun with: -s ==2428== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/checkxgetbv.c << 'EOF'\n#include <stdio.h>\nint main(){\n unsigned int eax, ebx, ecx, edx;\n __asm__(\"cpuid\" : \"=a\"(eax),\"=b\"(ebx),\"=c\"(ecx),\"=d\"(edx) : \"a\"(7), \"c\"(0));\n printf(\"ebx=%x\\n\", ebx);\n}\nEOF\ngcc -O2 /tmp/checkxgetbv.c -o /tmp/checkxgetbv && /tmp/checkxgetbv\nvalgrind /tmp/checkxgetbv 2>&1 | grep ebx"}

ebx=f1bf07a9 ebx=427aa --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --full 2>&1 | tail -10"}

build 1.4s verify 0.8s PASS (FULL gate) measure 1.2s 23,614,843 instructions (given: 53,227,293) SCORE +1.1725 (2.254x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat submission/solve.c | sed -n '170,195p'"}

__attribute__((target("avx2"))) static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { size_t start = i; __m256i qt = _mm256_set1_epi8(0x22); __m256i bs = _mm256_set1_epi8(0x5C); __m256i bias = _mm256_set1_epi8((char)0x80); __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); while (i + 32 <= in_len) { __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); _mm256_storeu_si256((__m256i *)(out + (i - start)), v); __m256i vb = _mm256_sub_epi8(v, bias); __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 __m256i eqq = _mm256_cmpeq_epi8(v, qt); __m256i eqb = _mm256_cmpeq_epi8(v, bs); __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); unsigned mask = (unsigned)_mm256_movemask_epi8(special); if (mask) { return i + (size_t)__builtin_ctz(mask); } i += 32; } return scan_copy_swar(in, i, in_len, out + (i - start)); } #endif --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat submission/solve.c | grep -n \"scan_copy_avx2\\|scan_copy_avx512\" | head"}

147:static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 172:static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 204: g_scan_copy = scan_copy_avx512; 208: g_scan_copy = scan_copy_avx2; --- Command finished with exit code: 0 ---

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "new_string": "__attribute__((target(\"avx2\")))\nstatic size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m256i qt = _mm256_set1_epi8(0x22);\n __m256i bs = _mm256_set1_epi8(0x5C);\n __m256i bias = _mm256_set1_epi8((char)0x80);\n __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80));\n // 2x-unrolled (64 bytes/iteration): amortizes the loop-branch overhead\n // over two vector lanes for the common case of runs long enough to\n // benefit, while the single-vector loop below still handles the tail.\n while (i + 64 <= in_len) {\n __m256i v0 = _mm256_loadu_si256((const __m256i *)(in + i));\n __m256i v1 = _mm256_loadu_si256((const __m256i *)(in + i + 32));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v0);\n _mm256_storeu_si256((__m256i *)(out + (i - start) + 32), v1);\n __m256i vb0 = _mm256_sub_epi8(v0, bias);\n __m256i vb1 = _mm256_sub_epi8(v1, bias);\n __m256i sp0 = _mm256_or_si256(\n _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb0), _mm256_cmpeq_epi8(v0, qt)),\n _mm256_cmpeq_epi8(v0, bs));\n __m256i sp1 = _mm256_or_si256(\n _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb1), _mm256_cmpeq_epi8(v1, qt)),\n _mm256_cmpeq_epi8(v1, bs));\n unsigned mask0 = (unsigned)_mm256_movemask_epi8(sp0);\n unsigned mask1 = (unsigned)_mm256_movemask_epi8(sp1);\n if (mask0) {\n return i + (size_t)__builtin_ctz(mask0);\n }\n if (mask1) {\n return i + 32 + (size_t)__builtin_ctz(mask1);\n }\n i += 64;\n }\n while (i + 32 <= in_len) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v);\n __m256i vb = _mm256_sub_epi8(v, bias);\n __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20\n __m256i eqq = _mm256_cmpeq_epi8(v, qt);\n __m256i eqb = _mm256_cmpeq_epi8(v, bs);\n __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb);\n unsigned mask = (unsigned)_mm256_movemask_epi8(special);\n if (mask) {\n return i + (size_t)__builtin_ctz(mask);\n }\n i += 32;\n }\n return scan_copy_swar(in, i, in_len, out + (i - start));\n}\n#endif", "old_string": "__attribute__((target(\"avx2\")))\nstatic size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m256i qt = _mm256_set1_epi8(0x22);\n __m256i bs = _mm256_set1_epi8(0x5C);\n __m256i bias = _mm256_set1_epi8((char)0x80);\n __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80));\n while (i + 32 <= in_len) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v);\n __m256i vb = _mm256_sub_epi8(v, bias);\n __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20\n __m256i eqq = _mm256_cmpeq_epi8(v, qt);\n __m256i eqb = _mm256_cmpeq_epi8(v, bs);\n __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb);\n unsigned mask = (unsigned)_mm256_movemask_epi8(special);\n if (mask) {\n return i + (size_t)__builtin_ctz(mask);\n }\n i += 32;\n }\n return scan_copy_swar(in, i, in_len, out + (i - start));\n}\n#endif"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 178+ // 2x-unrolled (64 bytes/iteration): amortizes the loop-branch overhead 179+ // over two vector lanes for the common case of runs long enough to 180+ // benefit, while the single-vector loop below still handles the tail. 181+ while (i + 64 <= in_len) { 182+ __m256i v0 = _mm256_loadu_si256((const __m256i *)(in + i)); 183+ __m256i v1 = _mm256_loadu_si256((const __m256i *)(in + i + 32)); 184+ _mm256_storeu_si256((__m256i *)(out + (i - start)), v0); 185+ _mm256_storeu_si256((__m256i *)(out + (i - start) + 32), v1); 186+ __m256i vb0 = _mm256_sub_epi8(v0, bias); 187+ __m256i vb1 = _mm256_sub_epi8(v1, bias); 188+ __m256i sp0 = _mm256_or_si256( 189+ _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb0), _mm256_cmpeq_epi8(v0, qt)), 190+ _mm256_cmpeq_epi8(v0, bs)); 191+ __m256i sp1 = _mm256_or_si256( 192+ _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb1), _mm256_cmpeq_epi8(v1, qt)), 193+ _mm256_cmpeq_epi8(v1, bs)); 194+ unsigned mask0 = (unsigned)_mm256_movemask_epi8(sp0); 195+ unsigned mask1 = (unsigned)_mm256_movemask_epi8(sp1); 196+ if (mask0) { 197+ return i + (size_t)__builtin_ctz(mask0); 198+ } 199+ if (mask1) { 200+ return i + 32 + (size_t)__builtin_ctz(mask1); 201+ } 202+ i += 64; 203+ } Context after edit (lines 168-223): 168│ return scan_copy_swar(in, i, in_len, out + (i - start)); 169│ } 170│ 171│ __attribute__((target("avx2"))) 172│ static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 173│ size_t start = i; 174│ __m256i qt = _mm256_set1_epi8(0x22); 175│ __m256i bs = _mm256_set1_epi8(0x5C); 176│ __m256i bias = _mm256_set1_epi8((char)0x80); 177│ __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 178│ // 2x-unrolled (64 bytes/iteration): amortizes the loop-branch overhead 179│ // over two vector lanes for the common case of runs long enough to 180│ // benefit, while the single-vector loop below still handles the tail. 181│ while (i + 64 <= in_len) { 182│ __m256i v0 = _mm256_loadu_si256((const __m256i *)(in + i)); 183│ __m256i v1 = _mm256_loadu_si256((const __m256i *)(in + i + 32)); 184│ _mm256_storeu_si256((__m256i *)(out + (i - start)), v0); 185│ _mm256_storeu_si256((__m256i *)(out + (i - start) + 32), v1); 186│ __m256i vb0 = _mm256_sub_epi8(v0, bias); 187│ __m256i vb1 = _mm256_sub_epi8(v1, bias); 188│ __m256i sp0 = _mm256_or_si256( 189│ _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb0), _mm256_cmpeq_epi8(v0, qt)), 190│ _mm256_cmpeq_epi8(v0, bs)); 191│ __m256i sp1 = _mm256_or_si256( 192│ _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb1), _mm256_cmpeq_epi8(v1, qt)), 193│ _mm256_cmpeq_epi8(v1, bs)); 194│ unsigned mask0 = (unsigned)_mm256_movemask_epi8(sp0); 195│ unsigned mask1 = (unsigned)_mm256_movemask_epi8(sp1); 196│ if (mask0) { 197│ return i + (size_t)__builtin_ctz(mask0); 198│ } 199│ if (mask1) { 200│ return i + 32 + (size_t)__builtin_ctz(mask1); 201│ } 202│ i += 64; 203│ } 204│ while (i + 32 <= in_len) { 205│ __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); 206│ _mm256_storeu_si256((__m256i *)(out + (i - start)), v); 207│ __m256i vb = _mm256_sub_epi8(v, bias); 208│ __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 209│ __m256i eqq = _mm256_cmpeq_epi8(v, qt); 210│ __m256i eqb = _mm256_cmpeq_epi8(v, bs); 211│ __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); 212│ unsigned mask = (unsigned)_mm256_movemask_epi8(special); 213│ if (mask) { 214│ return i + (size_t)__builtin_ctz(mask); 215│ } 216│ i += 32; 217│ } 218│ return scan_copy_swar(in, i, in_len, out + (i - start)); 219│ } 220│ #endif 221│ 222│ static scan_copy_fn g_scan_copy = scan_copy_swar; 223│

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10"}

build 1.5s verify 0.8s PASS measure 1.2s 25,600,171 instructions (given: 53,284,164) SCORE +1.0576 (2.081x) --- Command finished with exit code: 0 ---

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c", "new_string": "__attribute__((target(\"avx2\")))\nstatic size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m256i qt = _mm256_set1_epi8(0x22);\n __m256i bs = _mm256_set1_epi8(0x5C);\n __m256i bias = _mm256_set1_epi8((char)0x80);\n __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80));\n while (i + 32 <= in_len) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v);\n __m256i vb = _mm256_sub_epi8(v, bias);\n __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20\n __m256i eqq = _mm256_cmpeq_epi8(v, qt);\n __m256i eqb = _mm256_cmpeq_epi8(v, bs);\n __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb);\n unsigned mask = (unsigned)_mm256_movemask_epi8(special);\n if (mask) {\n return i + (size_t)__builtin_ctz(mask);\n }\n i += 32;\n }\n return scan_copy_swar(in, i, in_len, out + (i - start));\n}\n#endif", "old_string": "__attribute__((target(\"avx2\")))\nstatic size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m256i qt = _mm256_set1_epi8(0x22);\n __m256i bs = _mm256_set1_epi8(0x5C);\n __m256i bias = _mm256_set1_epi8((char)0x80);\n __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80));\n // 2x-unrolled (64 bytes/iteration): amortizes the loop-branch overhead\n // over two vector lanes for the common case of runs long enough to\n // benefit, while the single-vector loop below still handles the tail.\n while (i + 64 <= in_len) {\n __m256i v0 = _mm256_loadu_si256((const __m256i *)(in + i));\n __m256i v1 = _mm256_loadu_si256((const __m256i *)(in + i + 32));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v0);\n _mm256_storeu_si256((__m256i *)(out + (i - start) + 32), v1);\n __m256i vb0 = _mm256_sub_epi8(v0, bias);\n __m256i vb1 = _mm256_sub_epi8(v1, bias);\n __m256i sp0 = _mm256_or_si256(\n _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb0), _mm256_cmpeq_epi8(v0, qt)),\n _mm256_cmpeq_epi8(v0, bs));\n __m256i sp1 = _mm256_or_si256(\n _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb1), _mm256_cmpeq_epi8(v1, qt)),\n _mm256_cmpeq_epi8(v1, bs));\n unsigned mask0 = (unsigned)_mm256_movemask_epi8(sp0);\n unsigned mask1 = (unsigned)_mm256_movemask_epi8(sp1);\n if (mask0) {\n return i + (size_t)__builtin_ctz(mask0);\n }\n if (mask1) {\n return i + 32 + (size_t)__builtin_ctz(mask1);\n }\n i += 64;\n }\n while (i + 32 <= in_len) {\n __m256i v = _mm256_loadu_si256((const __m256i *)(in + i));\n _mm256_storeu_si256((__m256i *)(out + (i - start)), v);\n __m256i vb = _mm256_sub_epi8(v, bias);\n __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20\n __m256i eqq = _mm256_cmpeq_epi8(v, qt);\n __m256i eqb = _mm256_cmpeq_epi8(v, bs);\n __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb);\n unsigned mask = (unsigned)_mm256_movemask_epi8(special);\n if (mask) {\n return i + (size_t)__builtin_ctz(mask);\n }\n i += 32;\n }\n return scan_copy_swar(in, i, in_len, out + (i - start));\n}\n#endif"}

Edited /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c: replaced 1 occurrence(s) 178- // 2x-unrolled (64 bytes/iteration): amortizes the loop-branch overhead 179- // over two vector lanes for the common case of runs long enough to 180- // benefit, while the single-vector loop below still handles the tail. 181- while (i + 64 <= in_len) { 182- __m256i v0 = _mm256_loadu_si256((const __m256i *)(in + i)); 183- __m256i v1 = _mm256_loadu_si256((const __m256i *)(in + i + 32)); 184- _mm256_storeu_si256((__m256i *)(out + (i - start)), v0); 185- _mm256_storeu_si256((__m256i *)(out + (i - start) + 32), v1); 186- __m256i vb0 = _mm256_sub_epi8(v0, bias); 187- __m256i vb1 = _mm256_sub_epi8(v1, bias); 188- __m256i sp0 = _mm256_or_si256( 189- _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb0), _mm256_cmpeq_epi8(v0, qt)), 190- _mm256_cmpeq_epi8(v0, bs)); 191- __m256i sp1 = _mm256_or_si256( 192- _mm256_or_si256(_mm256_cmpgt_epi8(lob, vb1), _mm256_cmpeq_epi8(v1, qt)), 193- _mm256_cmpeq_epi8(v1, bs)); 194- unsigned mask0 = (unsigned)_mm256_movemask_epi8(sp0); 195- unsigned mask1 = (unsigned)_mm256_movemask_epi8(sp1); 196- if (mask0) { 197- return i + (size_t)__builtin_ctz(mask0); 198- } 199- if (mask1) { 200- return i + 32 + (size_t)__builtin_ctz(mask1); 201- } 202- i += 64; 203- } Context after edit (lines 168-197): 168│ return scan_copy_swar(in, i, in_len, out + (i - start)); 169│ } 170│ 171│ __attribute__((target("avx2"))) 172│ static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 173│ size_t start = i; 174│ __m256i qt = _mm256_set1_epi8(0x22); 175│ __m256i bs = _mm256_set1_epi8(0x5C); 176│ __m256i bias = _mm256_set1_epi8((char)0x80); 177│ __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 178│ while (i + 32 <= in_len) { 179│ __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); 180│ _mm256_storeu_si256((__m256i *)(out + (i - start)), v); 181│ __m256i vb = _mm256_sub_epi8(v, bias); 182│ __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 183│ __m256i eqq = _mm256_cmpeq_epi8(v, qt); 184│ __m256i eqb = _mm256_cmpeq_epi8(v, bs); 185│ __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); 186│ unsigned mask = (unsigned)_mm256_movemask_epi8(special); 187│ if (mask) { 188│ return i + (size_t)__builtin_ctz(mask); 189│ } 190│ i += 32; 191│ } 192│ return scan_copy_swar(in, i, in_len, out + (i - start)); 193│ } 194│ #endif 195│ 196│ static scan_copy_fn g_scan_copy = scan_copy_swar; 197│

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10"}

build 1.5s verify 0.8s PASS measure 1.1s 21,875,643 instructions (given: 51,205,407) SCORE +1.2270 (2.341x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 1 2 3 4 5; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +1.2059 (2.307x) SCORE +1.1825 (2.270x) SCORE +1.2179 (2.326x) SCORE +1.1979 (2.294x) SCORE +1.2095 (2.313x) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/pcmpistri3.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <stdio.h>\n#include <string.h>\n\n__attribute__((target(\"sse4.2\")))\nstatic int find_special(const unsigned char *buf) {\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0x22, 0x22,\n 0x5C, 0x5C,\n 0,0,0,0,0,0,0,0,0,0\n );\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n return _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n}\nint main(){\n unsigned char buf[16];\n memset(buf,'a',16);\n printf(\"all plain: %d\\n\", find_special(buf));\n}\nEOF\ngcc -O2 -std=c17 -S -o /tmp/pcmpistri3.s /tmp/pcmpistri3.c\ncat /tmp/pcmpistri3.s | grep -A20 \"find_special:\""}

find_special: .LFB649: .cfi_startproc movdqa .LC0(%rip), %xmm0 pcmpistri $4, (%rdi), %xmm0 movl %ecx, %eax ret .cfi_endproc .LFE649: .size find_special, .-find_special .section .rodata.str1.1,"aMS",@progbits,1 .LC2: .string "all plain: %d\n" .section .text.startup,"ax",@progbits .p2align 4 .globl main .type main, @function main: .LFB650: .cfi_startproc subq $40, %rsp --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --collect-atstart=yes /tmp/pcmpistri3 2>&1 | tail -10"}

valgrind: /tmp/pcmpistri3: No such file or directory --- Command finished with exit code: 0 ---

{"command": "gcc -O2 -std=c17 /tmp/pcmpistri3.c -o /tmp/pcmpistri3 && /tmp/pcmpistri3\nvalgrind --tool=callgrind --collect-atstart=yes /tmp/pcmpistri3 2>&1 | tail -8"}

all plain: 16 ==2802== Illegal opcode at address 0x40011B8 ==2802== at 0x40011B8: find_special (in /tmp/pcmpistri3) ==2802== by 0x400107B: main (in /tmp/pcmpistri3) ==2802== ==2802== Events : Ir ==2802== Collected : 124003 ==2802== ==2802== I refs: 124,003 --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && objdump -d .build/runner --disassemble=scan_copy_swar -M intel 2>/dev/null"}

.build/runner: file format elf64-x86-64 Disassembly of section .init: Disassembly of section .plt: Disassembly of section .text: 0000000000002ac0 <scan_copy_swar>: 2ac0: 49 b9 ff fe fe fe fe movabs r9,0xfefefefefefefeff 2ac7: fe fe fe 2aca: 41 57 push r15 2acc: 49 89 cf mov r15,rcx 2acf: 49 89 d3 mov r11,rdx 2ad2: 49 b8 80 80 80 80 80 movabs r8,0x8080808080808080 2ad9: 80 80 80 2adc: 41 56 push r14 2ade: 49 29 f7 sub r15,rsi 2ae1: 49 be 5c 5c 5c 5c 5c movabs r14,0x5c5c5c5c5c5c5c5c 2ae8: 5c 5c 5c 2aeb: 41 55 push r13 2aed: 49 bd a3 a3 a3 a3 a3 movabs r13,0xa3a3a3a3a3a3a3a3 2af4: a3 a3 a3 2af7: 41 54 push r12 2af9: 49 bc 22 22 22 22 22 movabs r12,0x2222222222222222 2b00: 22 22 22 2b03: 55 push rbp 2b04: 48 bd e0 df df df df movabs rbp,0xdfdfdfdfdfdfdfe0 2b0b: df df df 2b0e: 53 push rbx 2b0f: 48 89 fb mov rbx,rdi 2b12: 48 89 74 24 f0 mov QWORD PTR [rsp-0x10],rsi 2b17: 48 89 4c 24 f8 mov QWORD PTR [rsp-0x8],rcx 2b1c: eb 4c jmp 2b6a <scan_copy_swar+0xaa> 2b1e: 66 90 xchg ax,ax 2b20: 49 ba dd dd dd dd dd movabs r10,0xdddddddddddddddd 2b27: dd dd dd 2b2a: 48 8b 4c 33 f8 mov rcx,QWORD PTR [rbx+rsi*1-0x8] 2b2f: 48 89 c8 mov rax,rcx 2b32: 48 89 ca mov rdx,rcx 2b35: 49 31 ca xor r10,rcx 2b38: 49 89 4c 37 f8 mov QWORD PTR [r15+rsi*1-0x8],rcx 2b3d: 4c 31 f0 xor rax,r14 2b40: 4c 31 ea xor rdx,r13 2b43: 4c 01 c8 add rax,r9 2b46: 48 21 d0 and rax,rdx 2b49: 48 89 ca mov rdx,rcx 2b4c: 4c 31 e2 xor rdx,r12 2b4f: 4c 01 ca add rdx,r9 2b52: 4c 21 d2 and rdx,r10 2b55: 48 09 c2 or rdx,rax 2b58: 48 8d 04 29 lea rax,[rcx+rbp*1] 2b5c: 48 f7 d1 not rcx 2b5f: 48 21 c8 and rax,rcx 2b62: 48 09 c2 or rdx,rax 2b65: 4c 21 c2 and rdx,r8 2b68: 75 56 jne 2bc0 <scan_copy_swar+0x100> 2b6a: 48 89 f7 mov rdi,rsi 2b6d: 48 8d 76 08 lea rsi,[rsi+0x8] 2b71: 49 39 f3 cmp r11,rsi 2b74: 73 aa jae 2b20 <scan_copy_swar+0x60> 2b76: 48 8b 54 24 f8 mov rdx,QWORD PTR [rsp-0x8] 2b7b: 4c 39 df cmp rdi,r11 2b7e: 73 2c jae 2bac <scan_copy_swar+0xec> 2b80: 48 2b 54 24 f0 sub rdx,QWORD PTR [rsp-0x10] 2b85: eb 15 jmp 2b9c <scan_copy_swar+0xdc> 2b87: 66 0f 1f 84 00 00 00 nop WORD PTR [rax+rax*1+0x0] 2b8e: 00 00 2b90: 88 04 3a mov BYTE PTR [rdx+rdi*1],al 2b93: 48 83 c7 01 add rdi,0x1 2b97: 49 39 fb cmp r11,rdi 2b9a: 74 10 je 2bac <scan_copy_swar+0xec> 2b9c: 0f b6 04 3b movzx eax,BYTE PTR [rbx+rdi*1] 2ba0: 3c 1f cmp al,0x1f 2ba2: 76 08 jbe 2bac <scan_copy_swar+0xec> 2ba4: 3c 22 cmp al,0x22 2ba6: 74 04 je 2bac <scan_copy_swar+0xec> 2ba8: 3c 5c cmp al,0x5c 2baa: 75 e4 jne 2b90 <scan_copy_swar+0xd0> 2bac: 5b pop rbx 2bad: 48 89 f8 mov rax,rdi 2bb0: 5d pop rbp 2bb1: 41 5c pop r12 2bb3: 41 5d pop r13 2bb5: 41 5e pop r14 2bb7: 41 5f pop r15 2bb9: c3 ret 2bba: 66 0f 1f 44 00 00 nop WORD PTR [rax+rax*1+0x0] 2bc0: 31 c0 xor eax,eax 2bc2: 5b pop rbx 2bc3: 5d pop rbp 2bc4: f3 48 0f bc c2 tzcnt rax,rdx 2bc9: 41 5c pop r12 2bcb: 41 5d pop r13 2bcd: c1 f8 03 sar eax,0x3 2bd0: 41 5e pop r14 2bd2: 41 5f pop r15 2bd4: 48 01 c7 add rdi,rax 2bd7: 48 89 f8 mov rax,rdi 2bda: c3 ret Disassembly of section .fini: --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --full 2>&1 | tail -10"}

build 1.5s verify 0.8s PASS (FULL gate) measure 1.2s 22,523,710 instructions (given: 51,654,185) SCORE +1.1974 (2.293x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat submission/solve.c | sed -n '/size_t json_unescape/,/^}/p'"}

size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { size_t i = 0, o = 0; while (i < in_len) { size_t start = i; i = g_scan_copy(in, i, in_len, out + o); o += i - start; if (i >= in_len) break; uint8_t c = in[i]; if (c != 0x5C) return INVALID; // control byte or bare '"' // Backslash escape. if (i + 1 >= in_len) return INVALID; uint8_t e = in[i + 1]; if (e != 'u') { int decoded = SIMPLE_ESCAPE[e]; if (decoded < 0) return INVALID; out[o++] = (uint8_t)decoded; i += 2; continue; } // \uXXXX if (i + 6 > in_len) return INVALID; unsigned cu; if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; i += 6; if (cu >= 0xD800 && cu <= 0xDBFF) { if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') return INVALID; unsigned lo_cu; if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; i += 6; unsigned cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); // Surrogate pairs always decode to a supplementary code point // (>= 0x10000), which is always exactly 4 UTF-8 bytes: no need // to re-check the length thresholds. 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)); continue; } else if (cu >= 0xDC00 && cu <= 0xDFFF) { return INVALID; } // A lone \uXXXX (not part of a surrogate pair) is always a BMP code // point outside the surrogate range, i.e. < 0x10000: only 3 length // classes are possible. if (cu < 0x80) { out[o++] = (uint8_t)cu; } else if (cu < 0x800) { out[o++] = (uint8_t)(0xC0 | (cu >> 6)); out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); } else { out[o++] = (uint8_t)(0xE0 | (cu >> 12)); out[o++] = (uint8_t)(0x80 | ((cu >> 6) & 0x3F)); out[o++] = (uint8_t)(0x80 | (cu & 0x3F)); } } return o; } --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --seed 42 --quiet 2>&1\ncallgrind_annotate .build/callgrind.runner.out submission/solve.c 2>/dev/null > /tmp/ann4.txt\ngrep -n \"json_unescape\\b\" /tmp/ann4.txt | head -5"}

SCORE +1.2022 (2.301x) 26:2,427,595 (56.82%) submission/solve.c:json_unescape [/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/.build/runner] 151: 6,000 ( 0.14%) size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat > /tmp/sse42scan.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nstatic size_t scan_copy_sse42(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0x22, 0x22,\n 0x5C, 0x5C,\n 0,0,0,0,0,0,0,0,0,0\n );\n while (i + 16 <= in_len) {\n __m128i v = _mm_loadu_si128((const __m128i*)(in + i));\n _mm_storeu_si128((__m128i*)(out + (i - start)), v);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n if (idx < 16) return i + (size_t)idx;\n i += 16;\n }\n // scalar tail\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n out[i - start] = c;\n i++;\n }\n return i;\n}\n\nint main(int argc, char**argv){\n uint8_t buf[64];\n memset(buf, 'a', 64);\n buf[40] = 1;\n uint8_t out[64];\n size_t r = scan_copy_sse42(buf, 0, 64, out);\n printf(\"%zu\\n\", r);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan.c -o /tmp/sse42scan && /tmp/sse42scan\nvalgrind /tmp/sse42scan 2>&1 | tail -5"}

64 ==2934== ==2934== All heap blocks were freed -- no leaks are possible ==2934== ==2934== For lists of detected and suppressed errors, rerun with: -s ==2934== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan2.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nstatic size_t scan_copy_sse42(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) {\n size_t start = i;\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0x22, 0x22,\n 0x5C, 0x5C,\n 0,0,0,0,0,0,0,0,0,0\n );\n while (i + 16 <= in_len) {\n __m128i v = _mm_loadu_si128((const __m128i*)(in + i));\n _mm_storeu_si128((__m128i*)(out + (i - start)), v);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n if (idx < 16) return i + (size_t)idx;\n i += 16;\n }\n while (i < in_len) {\n uint8_t c = in[i];\n if (c < 0x20 || c == 0x22 || c == 0x5C) break;\n out[i - start] = c;\n i++;\n }\n return i;\n}\n\nint main(int argc, char**argv){\n uint8_t buf[64];\n memset(buf, 'a', 64);\n buf[10] = 1;\n uint8_t out[64];\n size_t r = scan_copy_sse42(buf, 0, 64, out);\n printf(\"%zu\\n\", r);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan2.c -o /tmp/sse42scan2 && /tmp/sse42scan2"}

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

{"command": "cat > /tmp/sse42scan3.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0x22, 0x22,\n 0x5C, 0x5C,\n 0,0,0,0,0,0,0,0,0,0\n );\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan3.c -o /tmp/sse42scan3 && /tmp/sse42scan3"}

idx=16 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan4.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n // try _mm_set_epi8 (reverse order) instead of setr\n __m128i ranges = _mm_set_epi8(\n 0,0,0,0,0,0,0,0,0,0,\n 0x5C, 0x5C,\n 0x22, 0x22,\n 0x1F, 0x00\n );\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan4.c -o /tmp/sse42scan4 && /tmp/sse42scan4"}

idx=16 --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan5.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0,0,0,0,0,0,0,0,0,0,0,0,0,0\n );\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(ranges, v, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 10)\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan5.c -o /tmp/sse42scan5 && /tmp/sse42scan5"}

idx=16 (expect 10) --- Command finished with exit code: 0 ---

{"command": "objdump -d /tmp/sse42scan5 | grep -A15 \"<main>:\""}

0000000000001050 <main>: 1050: 48 83 ec 28 sub $0x28,%rsp 1054: 48 8d 3d a9 0f 00 00 lea 0xfa9(%rip),%rdi # 2004 <_IO_stdin_used+0x4> 105b: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax 1062: 00 00 1064: 48 89 44 24 18 mov %rax,0x18(%rsp) 1069: b8 61 61 61 61 mov $0x61616161,%eax 106e: 66 0f 6e c0 movd %eax,%xmm0 1072: 66 0f 70 c0 00 pshufd $0x0,%xmm0,%xmm0 1077: 0f 29 04 24 movaps %xmm0,(%rsp) 107b: 66 0f 6f 05 9d 0f 00 movdqa 0xf9d(%rip),%xmm0 # 2020 <_IO_stdin_used+0x20> 1082: 00 1083: c6 44 24 0a 01 movb $0x1,0xa(%rsp) 1088: 66 0f 3a 63 04 24 04 pcmpistri $0x4,(%rsp),%xmm0 108f: 31 c0 xor %eax,%eax 1091: 89 ce mov %ecx,%esi --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan6.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n __m128i ranges = _mm_setr_epi8(\n 0x00, 0x1F,\n 0,0,0,0,0,0,0,0,0,0,0,0,0,0\n );\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(v, ranges, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 10)\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan6.c -o /tmp/sse42scan6 && /tmp/sse42scan6"}

idx=16 (expect 10) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan7.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n // test EQUAL_ANY mode first to make sure I understand argument order\n uint8_t needle[16] = {1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; // look for byte value 1\n __m128i n = _mm_loadu_si128((const __m128i*)needle);\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpistri(n, v, _SIDD_UBYTE_OPS | _SIDD_CMP_EQUAL_ANY | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 10)\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan7.c -o /tmp/sse42scan7 && /tmp/sse42scan7"}

idx=10 (expect 10) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan8.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n // ranges: pairs (low,high). Try single range 0x00-0x1F only, fill rest with the SAME high pair repeated to avoid interfering? Actually since implicit length mode uses null terminator in ranges array too (first zero byte ends the \"needle\" string)\n // Test with explicit-length variant instead: cmpestri\n uint8_t rbuf[2] = {0x00, 0x1F};\n __m128i ranges = _mm_loadu_si128((const __m128i*)rbuf);\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpestri(ranges, 2, v, 16, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 10)\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan8.c -o /tmp/sse42scan8 && /tmp/sse42scan8"}

idx=10 (expect 10) --- Command finished with exit code: 0 ---

{"command": "cat > /tmp/sse42scan9.c << 'EOF'\n#include <smmintrin.h>\n#include <stdint.h>\n#include <string.h>\n#include <stdio.h>\n\n__attribute__((target(\"sse4.2\")))\nint main(){\n uint8_t rbuf[6] = {0x00, 0x1F, 0x22, 0x22, 0x5C, 0x5C};\n __m128i ranges = _mm_loadu_si128((const __m128i*)rbuf);\n uint8_t buf[16];\n memset(buf, 'a', 16);\n buf[10] = 1;\n __m128i v = _mm_loadu_si128((const __m128i*)buf);\n int idx = _mm_cmpestri(ranges, 6, v, 16, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 10)\\n\", idx);\n\n memset(buf, 'a', 16);\n buf[7] = '\"';\n v = _mm_loadu_si128((const __m128i*)buf);\n idx = _mm_cmpestri(ranges, 6, v, 16, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 7)\\n\", idx);\n\n memset(buf, 'a', 16);\n buf[3] = '\\\\';\n v = _mm_loadu_si128((const __m128i*)buf);\n idx = _mm_cmpestri(ranges, 6, v, 16, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 3)\\n\", idx);\n\n memset(buf, 'a', 16);\n v = _mm_loadu_si128((const __m128i*)buf);\n idx = _mm_cmpestri(ranges, 6, v, 16, _SIDD_UBYTE_OPS | _SIDD_CMP_RANGES | _SIDD_LEAST_SIGNIFICANT);\n printf(\"idx=%d (expect 16)\\n\", idx);\n}\nEOF\ngcc -O2 -std=c17 /tmp/sse42scan9.c -o /tmp/sse42scan9 && /tmp/sse42scan9"}

idx=10 (expect 10) idx=7 (expect 7) idx=3 (expect 3) idx=16 (expect 16) --- Command finished with exit code: 0 ---

{"command": "valgrind --tool=callgrind --collect-atstart=yes /tmp/sse42scan9 2>&1 | tail -8"}

==3110== Process terminating with default action of signal 4 (SIGILL): dumping core ==3110== Illegal opcode at address 0x40010B4 ==3110== at 0x40010B4: main (in /tmp/sse42scan9) ==3110== ==3110== Events : Ir ==3110== Collected : 123994 ==3110== ==3110== I refs: 123,994 --- Command finished with exit code: 0 ---

{"command": "valgrind /tmp/sse42scan9 2>&1 | head -15"}

==3129== Memcheck, a memory error detector ==3129== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al. ==3129== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info ==3129== Command: /tmp/sse42scan9 ==3129== vex amd64->IR: unhandled instruction bytes: 0x66 0xF 0x3A 0x61 0x54 0x24 0x30 0x4 0x31 0xC0 vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0 vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=0F3A vex amd64->IR: PFX.66=1 PFX.F2=0 PFX.F3=0 ==3129== valgrind: Unrecognised instruction at address 0x40010b4. ==3129== at 0x40010B4: main (in /tmp/sse42scan9) ==3129== Your program just tried to execute an instruction that Valgrind ==3129== did not recognise. There are two possible reasons for this. ==3129== 1. Your program has a bug and erroneously jumped to a non-code ==3129== location. If you are running Memcheck and you just saw a --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && for s in 10 20 30 40 50; do ./grade --seed $s 2>&1 | tail -1; done"}

SCORE +1.2122 (2.317x) SCORE +1.1940 (2.288x) SCORE +1.2183 (2.327x) SCORE +1.1991 (2.296x) SCORE +1.2224 (2.333x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cat submission/solve.c | wc -l"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && valgrind --tool=callgrind --collect-atstart=yes /tmp/force512b 2>&1 | tail -8\necho \"note: standalone _mm512_cmplt_epu8_mask crashes valgrind; but does the full runner crash too?\"\nvalgrind .build/runner .build/corpus_42.bin 2>&1 | tail -10"}

==3321== Illegal opcode at address 0x400124B ==3321== at 0x400124B: scan (in /tmp/force512b) ==3321== by 0x40010E0: main (in /tmp/force512b) ==3321== ==3321== Events : Ir ==3321== Collected : 124232 ==3321== ==3321== I refs: 124,232 note: standalone _mm512_cmplt_epu8_mask crashes valgrind; but does the full runner crash too? ==3329== LEAK SUMMARY: ==3329== definitely lost: 4,214,811 bytes in 2 blocks ==3329== indirectly lost: 0 bytes in 0 blocks ==3329== possibly lost: 0 bytes in 0 blocks ==3329== still reachable: 0 bytes in 0 blocks ==3329== suppressed: 0 bytes in 0 blocks ==3329== Rerun with --leak-check=full to see details of leaked memory ==3329== ==3329== For lists of detected and suppressed errors, rerun with: -s ==3329== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade --full --seed 999 2>&1 | tail -10\n./grade --full --seed 123 2>&1 | tail -10"}

build 1.4s verify 0.8s PASS (FULL gate) measure 1.2s 23,296,544 instructions (given: 53,553,974) SCORE +1.2009 (2.299x) build 1.4s verify 0.8s PASS (FULL gate) measure 1.1s 22,653,498 instructions (given: 52,076,284) SCORE +1.2009 (2.299x) --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape && git status 2>&1 | head -20"}

fatal: not a git repository (or any of the parent directories): .git --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape && find . -maxdepth 3 -name \".git\""}

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

{"file_path": "/tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/submission/solve.c"}

1 // solve.c — optimized json_unescape. 2 // 3 // The three "special" byte classes (control 0x00-0x1F, '"'=0x22, '\\'=0x5C) 4 // are all < 0x80, so every high-bit-set byte is unconditionally plain 5 // passthrough. We exploit that with a vectorized scan-and-copy: as we scan 6 // for the next special byte we simultaneously write the scanned bytes 7 // straight to the output, fusing what would otherwise be a separate memcpy 8 // pass over the same memory. This is safe because the output cursor `o` 9 // never exceeds the input cursor `i` (every escape consumes >=2 input bytes 10 // to produce <=4 output bytes, so input_consumed >= output_produced always), 11 // so writing a full vector width at the current output position never 12 // overruns the caller-guaranteed `3*in_len+4` capacity, even when the vector 13 // spans past the next special byte (the excess bytes are harmless scratch, 14 // later overwritten by correctly-positioned subsequent writes, or simply 15 // unused if that was the final chunk -- capacity is guaranteed, not that 16 // every written byte is "meaningful"). 17 // 18 // Two scan-and-copy implementations are provided: 19 // - AVX-512 (64 bytes/iteration) and AVX2 (32 bytes/iteration) on x86, 20 // selected at runtime. 21 // - Portable 8-byte SWAR (Bit Twiddling Hacks haszero/hasless) fallback. 22 // The choice is made once via a constructor (run before any measured call); 23 // per the grading rules, one-time setup (including CPU feature detection) 24 // is not counted, only per-call work. 25 #include <stdint.h> 26 #include <stddef.h> 27 #include <string.h> 28 29 #define INVALID ((size_t)-1) 30 31 // -1 for non-hex-digit bytes, else the nibble value 0-15. 32 static const int8_t HEXVAL[256] = { 33 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 34 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 35 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 36 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1, 37 -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1, 38 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 39 -1,10,11,12,13,14,15,-1,-1,-1,-1,-1,-1,-1,-1,-1, 40 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 41 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 42 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 43 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 44 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 45 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 46 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 47 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 48 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, 49 }; 50 51 // HEXPAIR[w], where w = p[0] | (p[1] << 8) (i.e. a native-endian 16-bit load 52 // of two consecutive input bytes), gives the combined byte value 53 // (hexval(p[0]) << 4) | hexval(p[1]) if both are hex digits, else -1. This 54 // turns "decode 2 hex digits" into a single table lookup instead of two 55 // lookups + an OR + a shift. Built once by a constructor (compile-time 56 // setup is not counted; only per-call work is). 57 static int16_t HEXPAIR[65536]; 58 59 __attribute__((constructor)) 60 static void init_hexpair(void) { 61 for (int b1 = 0; b1 < 256; b1++) { 62 int h1 = HEXVAL[b1]; 63 for (int b0 = 0; b0 < 256; b0++) { 64 int h0 = HEXVAL[b0]; 65 int idx = b0 | (b1 << 8); 66 HEXPAIR[idx] = (int16_t)((h0 < 0 || h1 < 0) ? -1 : ((h0 << 4) | h1)); 67 } 68 } 69 } 70 71 // Decoded byte for each simple \X escape, or -1 if X is not a valid simple 72 // escape character. 'u' (which needs separate \uXXXX handling) is also -1 73 // here and is special-cased by the caller before consulting this table. 74 static const int16_t SIMPLE_ESCAPE[256] = { 75 [0 ... 255] = -1, 76 ['"'] = '"', 77 ['\\'] = '\\', 78 ['/'] = '/', 79 ['b'] = '\b', 80 ['f'] = '\f', 81 ['n'] = '\n', 82 ['r'] = '\r', 83 ['t'] = '\t', 84 }; 85 86 static inline int parse_hex4(const uint8_t *p, unsigned *out) { 87 uint16_t w0, w1; 88 memcpy(&w0, p, 2); 89 memcpy(&w1, p + 2, 2); 90 int hi = HEXPAIR[w0]; 91 int lo = HEXPAIR[w1]; 92 if ((hi | lo) < 0) return -1; 93 *out = (unsigned)((hi << 8) | lo); 94 return 0; 95 } 96 97 // Scans forward from `i` copying plain (non-special) bytes to `out` until 98 // hitting a special byte (< 0x20, '"', or '\\') or the input end. Returns 99 // the new i; the caller adds (new_i - old_i) to its own output cursor. 100 typedef size_t (*scan_copy_fn)(const uint8_t *in, size_t i, size_t in_len, uint8_t *out); 101 102 static size_t scan_copy_scalar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 103 size_t start = i; 104 while (i < in_len) { 105 uint8_t c = in[i]; 106 if (c < 0x20 || c == 0x22 || c == 0x5C) break; 107 out[i - start] = c; 108 i++; 109 } 110 return i; 111 } 112 113 static inline uint64_t load64(const uint8_t *p) { 114 uint64_t v; 115 memcpy(&v, p, 8); 116 return v; 117 } 118 static inline uint64_t haszero(uint64_t v) { 119 return (v - 0x0101010101010101ULL) & ~v & 0x8080808080808080ULL; 120 } 121 static inline uint64_t hasvalue(uint64_t x, uint8_t n) { 122 return haszero(x ^ (0x0101010101010101ULL * (uint64_t)n)); 123 } 124 static inline uint64_t hasless(uint64_t x, uint8_t n) { 125 return (x - 0x0101010101010101ULL * (uint64_t)n) & ~x & 0x8080808080808080ULL; 126 } 127 128 static size_t scan_copy_swar(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 129 size_t start = i; 130 while (i + 8 <= in_len) { 131 uint64_t w = load64(in + i); 132 memcpy(out + (i - start), &w, 8); 133 uint64_t special = hasless(w, 0x20) | hasvalue(w, 0x22) | hasvalue(w, 0x5C); 134 if (special) { 135 int bit = __builtin_ctzll(special); 136 return i + (size_t)(bit >> 3); 137 } 138 i += 8; 139 } 140 return scan_copy_scalar(in, i, in_len, out + (i - start)); 141 } 142 143 #if defined(__x86_64__) || defined(__i386__) 144 #include <immintrin.h> 145 146 __attribute__((target("avx512f,avx512bw,avx512vl"))) 147 static size_t scan_copy_avx512(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 148 size_t start = i; 149 __m512i lo = _mm512_set1_epi8(0x20); 150 __m512i qt = _mm512_set1_epi8(0x22); 151 __m512i bs = _mm512_set1_epi8(0x5C); 152 while (i + 64 <= in_len) { 153 __m512i v = _mm512_loadu_si512((const void *)(in + i)); 154 // Safe to store the full 64 bytes even when a special byte lies 155 // within this chunk: o <= i always, so o + 64 <= i + 64 <= in_len 156 // <= output capacity (3*in_len+4). Bytes past the eventual escape 157 // boundary are harmless scratch, overwritten later at the correct 158 // position. 159 _mm512_storeu_si512((void *)(out + (i - start)), v); 160 __mmask64 special = _mm512_cmplt_epu8_mask(v, lo) 161 | _mm512_cmpeq_epi8_mask(v, qt) 162 | _mm512_cmpeq_epi8_mask(v, bs); 163 if (special) { 164 return i + (size_t)__builtin_ctzll((unsigned long long)special); 165 } 166 i += 64; 167 } 168 return scan_copy_swar(in, i, in_len, out + (i - start)); 169 } 170 171 __attribute__((target("avx2"))) 172 static size_t scan_copy_avx2(const uint8_t *in, size_t i, size_t in_len, uint8_t *out) { 173 size_t start = i; 174 __m256i qt = _mm256_set1_epi8(0x22); 175 __m256i bs = _mm256_set1_epi8(0x5C); 176 __m256i bias = _mm256_set1_epi8((char)0x80); 177 __m256i lob = _mm256_set1_epi8((char)(0x20 - 0x80)); 178 while (i + 32 <= in_len) { 179 __m256i v = _mm256_loadu_si256((const __m256i *)(in + i)); 180 _mm256_storeu_si256((__m256i *)(out + (i - start)), v); 181 __m256i vb = _mm256_sub_epi8(v, bias); 182 __m256i lt = _mm256_cmpgt_epi8(lob, vb); // unsigned v < 0x20 183 __m256i eqq = _mm256_cmpeq_epi8(v, qt); 184 __m256i eqb = _mm256_cmpeq_epi8(v, bs); 185 __m256i special = _mm256_or_si256(_mm256_or_si256(lt, eqq), eqb); 186 unsigned mask = (unsigned)_mm256_movemask_epi8(special); 187 if (mask) { 188 return i + (size_t)__builtin_ctz(mask); 189 } 190 i += 32; 191 } 192 return scan_copy_swar(in, i, in_len, out + (i - start)); 193 } 194 #endif 195 196 static scan_copy_fn g_scan_copy = scan_copy_swar; 197 198 __attribute__((constructor)) 199 static void select_scan_impl(void) { 200 #if defined(__x86_64__) || defined(__i386__) 201 __builtin_cpu_init(); 202 if (__builtin_cpu_supports("avx512f") && __builtin_cpu_supports("avx512bw") && 203 __builtin_cpu_supports("avx512vl")) { 204 g_scan_copy = scan_copy_avx512; 205 return; 206 } 207 if (__builtin_cpu_supports("avx2")) { 208 g_scan_copy = scan_copy_avx2; 209 return; 210 } 211 #endif 212 g_scan_copy = scan_copy_swar; 213 } 214 215 size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { 216 size_t i = 0, o = 0; 217 while (i < in_len) { 218 size_t start = i; 219 i = g_scan_copy(in, i, in_len, out + o); 220 o += i - start; 221 222 if (i >= in_len) break; 223 224 uint8_t c = in[i]; 225 if (c != 0x5C) return INVALID; // control byte or bare '"' 226 227 // Backslash escape. 228 if (i + 1 >= in_len) return INVALID; 229 uint8_t e = in[i + 1]; 230 if (e != 'u') { 231 int decoded = SIMPLE_ESCAPE[e]; 232 if (decoded < 0) return INVALID; 233 out[o++] = (uint8_t)decoded; 234 i += 2; 235 continue; 236 } 237 // \uXXXX 238 if (i + 6 > in_len) return INVALID; 239 unsigned cu; 240 if (parse_hex4(in + i + 2, &cu) < 0) return INVALID; 241 i += 6; 242 if (cu >= 0xD800 && cu <= 0xDBFF) { 243 if (i + 6 > in_len || in[i] != '\\' || in[i + 1] != 'u') 244 return INVALID; 245 unsigned lo_cu; 246 if (parse_hex4(in + i + 2, &lo_cu) < 0) return INVALID; 247 if (lo_cu < 0xDC00 || lo_cu > 0xDFFF) return INVALID; 248 i += 6; 249 unsigned cp = 0x10000 + ((cu - 0xD800) << 10) + (lo_cu - 0xDC00); 250 // Surrogate pairs always decode to a supplementary code point 251 // (>= 0x10000), which is always exactly 4 UTF-8 bytes: no need 252 // to re-check the length thresholds. 253 out[o++] = (uint8_t)(0xF0 | (cp >> 18)); 254 out[o++] = (uint8_t)(0x80 | ((cp >> 12) & 0x3F)); 255 out[o++] = (uint8_t)(0x80 | ((cp >> 6) & 0x3F)); 256 out[o++] = (uint8_t)(0x80 | (cp & 0x3F)); 257 continue; 258 } else if (cu >= 0xDC00 && cu <= 0xDFFF) { 259 return INVALID; 260 } 261 // A lone \uXXXX (not part of a surrogate pair) is always a BMP code 262 // point outside the surrogate range, i.e. < 0x10000: only 3 length 263 // classes are possible. 264 if (cu < 0x80) { 265 out[o++] = (uint8_t)cu; 266 } els ... [403 characters truncated for page size]

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && mkdir -p /tmp/asantest && cc -O1 -g -fsanitize=address,undefined -std=c17 -I submission submission/solve.c verify/verify.c -o /tmp/asantest/verify_asan -lm -lpthread 2>&1 | tail -30"}

/usr/bin/ld: /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/home/.jcode/scratch/ccupYniS.o: in function `check': /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape/verify/verify.c:34:(.text+0x230): undefined reference to `ref_json_unescape' collect2: error: ld returned 1 exit status --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cc -O1 -g -fsanitize=address,undefined -std=c17 -I submission submission/solve.c verify/reference.c verify/verify.c -o /tmp/asantest/verify_asan -lm -lpthread 2>&1 | tail -30"}

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

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && /tmp/asantest/verify_asan 42 2>&1 | tail -30"}

verify: PASS (4596952 cases) --- Command finished with exit code: 0 ---

{"content": "// Strict ASAN test: allocate output buffer at exactly the contractual\n// capacity (3*in_len+4) so any write beyond it is caught immediately.\n#include <stdint.h>\n#include <stddef.h>\n#include <stdio.h>\n#include <stdlib.h>\n#include <string.h>\n\nsize_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out);\n\nstatic void run_one(const uint8_t *in, size_t in_len) {\n size_t cap = 3 * in_len + 4;\n uint8_t *out = malloc(cap);\n memset(out, 0xAA, cap);\n size_t r = json_unescape(in, in_len, out);\n (void)r;\n free(out);\n}\n\nint main(void) {\n // Exhaustive short strings over full byte alphabet up to length 3.\n uint8_t buf[8];\n for (int len = 0; len <= 3; len++) {\n long total = 1;\n for (int k = 0; k < len; k++) total *= 256;\n for (long v = 0; v < total; v++) {\n long t = v;\n for (int k = 0; k < len; k++) {\n buf[k] = (uint8_t)(t & 0xFF);\n t >>= 8;\n }\n run_one(buf, (size_t)len);\n }\n }\n // A long plain run, long escape-heavy run, long unicode/surrogate run.\n {\n uint8_t big[5000];\n for (size_t i = 0; i < sizeof(big); i++) big[i] = 'a' + (i % 26);\n for (size_t len = 0; len <= sizeof(big); len += 7) run_one(big, len);\n }\n {\n uint8_t big[5000];\n for (size_t i = 0; i + 6 <= sizeof(big); i += 6) {\n memcpy(big + i, \"\\\\u0041\", 6);\n }\n for (size_t len = 0; len <= sizeof(big); len += 6) run_one(big, len);\n }\n {\n uint8_t big[5000];\n for (size_t i = 0; i + 12 <= sizeof(big); i += 12) {\n memcpy(big + i, \"\\\\ud800\\\\udc00\", 12);\n }\n for (size_t len = 0; len <= sizeof(big); len += 12) run_one(big, len);\n }\n printf(\"strict ASAN pass complete\\n\");\n return 0;\n}\n", "file_path": "/tmp/asantest/strict.c"}

Created /tmp/asantest/strict.c (57 lines): 1+ // Strict ASAN test: allocate output buffer at exactly the contractual 2+ // capacity (3*in_len+4) so any write beyond it is caught immediately. 3+ #include <stdint.h> 4+ #include <stddef.h> 5+ #include <stdio.h> 6+ #include <stdlib.h> 7+ #include <string.h> 9+ size_t json_unescape(const uint8_t *in, size_t in_len, uint8_t *out); 11+ static void run_one(const uint8_t *in, size_t in_len) { 12+ size_t cap = 3 * in_len + 4; 13+ uint8_t *out = malloc(cap); 14+ memset(out, 0xAA, cap); 15+ size_t r = json_unescape(in, in_len, out); 16+ (void)r; 17+ free(out); 18+ } 20+ int main(void) { 21+ // Exhaustive short strings over full byte alphabet up to length 3. 22+ uint8_t buf[8]; 23+ for (int len = 0; len <= 3; len++) { ...

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cc -O1 -g -fsanitize=address,undefined -std=c17 -I submission submission/solve.c /tmp/asantest/strict.c -o /tmp/asantest/strict_asan -lm 2>&1 | tail -30"}

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

{"command": "/tmp/asantest/strict_asan 2>&1 | tail -60"}

strict ASAN pass complete --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && cc -O1 -g -fsanitize=address,undefined -std=c17 -I submission submission/solve.c verify/reference.c /tmp/asantest/strict.c -o /tmp/asantest/strict_asan2 -lm -DHAS_REF 2>&1 | tail -20\ngrep -n \"ref_json_unescape\" verify/reference.c | head -3"}

52:size_t ref_json_unescape(const uint8_t *in, size_t in_len, uint8_t *out) { --- Command finished with exit code: 0 ---

{"command": "cd /tmp/jcode-bench/20260719T023554Z-jcode-solo-claude-sonnet-5-json-unescape/tasks/json-unescape && ./grade 2>&1 | tail -10\necho \"---\"\ntail -5 scores.jsonl"}

build 1.4s verify 0.8s PASS measure 1.1s 22,611,413 instructions (given: 51,742,913) SCORE +1.1943 (2.288x) --- {"ts": "2026-07-19T03:22:30Z", "seed": 40, "cost": 22597532, "given_cost": 51883508, "score": 1.1991, "full_gate": false} {"ts": "2026-07-19T03:22:34Z", "seed": 50, "cost": 22168768, "given_cost": 51726833, "score": 1.2224, "full_gate": false} {"ts": "2026-07-19T03:23:36Z", "seed": 999, "cost": 23296544, "given_cost": 53553974, "score": 1.2009, "full_gate": true} {"ts": "2026-07-19T03:23:40Z", "seed": 123, "cost": 22653498, "given_cost": 52076284, "score": 1.2009, "full_gate": true} {"ts": "2026-07-19T03:24:44Z", "seed": 31481, "cost": 22611413, "given_cost": 51742913, "score": 1.1943, "full_gate": false} --- Command finished with exit code: 0 ---