wcc/cgen: zero-init sub-8-byte bare lets, both stages; bytes test honest (#16-team)
A bare 'let x: T;' with 1 <= size(T) <= 7 matched no zero-fill arm in either stage (8B and >8B were already zeroed) - 'let c: [3]u8;' read stack garbage. User-ruled zero-value semantics: cstage gate sz>8 -> sz>0; wwstage zsz==8 arm hoisted above the fill-run arm (required - 8B would otherwise route into the run and diverge) and run gate zsz>0. New 840 pin: dirty-frame probe rows, dual-dim (run + cs/ww byte-id); discriminators fail exit-154 on pre-fix binaries. Fused with the lib/bytes test conversion (rule 11): either half alone turns 967 red. The old exit(signalled+10) wrapped a real 1782-count ltrim failure to exit 0 - green depended on the garbage. Converted to assert form (completes the 35/35 @test conversion); ltrim rows keep the bare 'let c: [3]u8;' as the consumer proof of the fix.
This commit is contained in:
271
test/wcc/840_zeroinit_run.c
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271
test/wcc/840_zeroinit_run.c
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/*
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* 840_zeroinit_run — task #16. A bare `let x: T;` (no initializer) must
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* zero-fill its slot (Go zero-value, rob's ruling). Before the fix, cgen
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* emitted the zero-fill ONLY for 8B-primitive slots and >8B composites; a
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* SUB-8 aggregate (`let c: [3]u8;` = 3 bytes, a 3-byte struct, …) matched
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* neither arm and fell through to NOTHING, so the slot read whatever the
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* stack held.
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*
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* THE BUG (cstage == wwstage, BOTH wrong — shared gap, NOT rule-10):
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* ken's bytes verdict (.ai/ken-bytes16-verdict.md) traced lib/bytes'
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* green-but-broken 967 to ltrim_cases' `let c: [3]u8;` reading a prior
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* deep-frame sibling's leftover bytes. The masking was a stack-zero
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* accident: a bare let on a FRESH frame happens to read 0, so the bug
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* only fires when a deep-framed fn ran first. byte-id was BLIND (#263):
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* both stages emitted the identical no-store sequence.
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*
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* REPRO SHAPE (ken's bytes-independent minimal repro, generalised):
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* dirty() writes a big local ([64]u8 = 222) to soil the stack region;
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* probe() then declares the bare let as its FIRST local — reusing
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* dirty()'s slot — and reads it. A correct zero-fill returns 0; the
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* pre-fix garbage returned (222 * width) & 0xff (154 for [3]u8).
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*
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* THE FIX (#16, both stages): widen the no-rhs zero-fill gate from
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* `sz > 8` to `sz > 0` (cgen.c N_LET) and add the symmetric `zsz > 0`
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* run arm (cgenstmt.ww cglet), so 1..7-byte slots zero through the same
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* MOVL/MOVB tail. sz == 8 keeps its immediate MOVQ $0; sz == 0 (`[0]T`)
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* needs no stores.
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*
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* EACH ROW CARRIES BOTH DIMENSIONS (802 model):
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* (a) cstage `ww build` + run, asserting exit 0 — pins that the bare let
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* reads zero even after a dirtied frame (runtime correctness the
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* byte-id gate cannot see).
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* (b) w6c vs w6c_ww `.s` cmp — FAILS if the stages diverge (rule-10).
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*
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* GATE POLARITY: must stay GREEN. A nonzero exit means a bare-let slot
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* regressed to reading stack garbage; a byte-id FAIL means the stages
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* diverged on the zero-fill emission.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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static int
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runwait(const char *cmd)
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{
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int rc = system(cmd);
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if (rc == -1) return -1;
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if (WIFEXITED(rc)) return WEXITSTATUS(rc);
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return -1;
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}
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struct row { const char *label; const char *src; int want_exit; };
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/* Every row shares the dirty()→probe() spine: dirty soils the frame,
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* probe declares the bare let FIRST and reads it. want_exit is 0 (all
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* reads zero). The discriminating rows are the SUB-8 aggregates ([3]u8,
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* [5]u8, [7]u8, the 3-byte struct) — the exact gap #16 closed; the
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* scalar / [20]u8 / str / slice rows are controls (already zeroed pre-#16
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* via the sz==8 and sz>8 arms) pinning no-regression. */
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static const struct row rows[] = {
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/* the exact ken repro: [3]u8 sub-8 array. Pre-fix returned 154. */
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{ "arr3_u8",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = {\n"
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" let c: [3]u8;\n"
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" return (c[0]: i32) + (c[1]: i32) + (c[2]: i32);\n"
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"};\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* sub-8, width 5 — exercises the MOVL+MOVB tail split (4 + 1). */
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{ "arr5_u8",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = {\n"
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" let c: [5]u8; let acc: i32 = 0; let j: i32 = 0;\n"
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" for (j < 5) { acc += (c[j]: i32); j += 1; };\n"
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" return acc;\n"
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"};\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* sub-8, width 7 — the widest sub-8 extent (MOVL + MOVW + MOVB is
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* unreachable under the run's 4/1 tail, so this is MOVL + 3×MOVB). */
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{ "arr7_u8",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = {\n"
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" let c: [7]u8; let acc: i32 = 0; let j: i32 = 0;\n"
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" for (j < 7) { acc += (c[j]: i32); j += 1; };\n"
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" return acc;\n"
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"};\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* sub-8 STRUCT (3 bytes) — the non-array half of the gap. Read each
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* field; a garbage slot would sum nonzero. */
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{ "struct3_u8",
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"package main;\n"
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"type S = struct { a: u8, b: u8, c: u8 };\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = {\n"
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" let s: S;\n"
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" return (s.a: i32) + (s.b: i32) + (s.c: i32);\n"
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"};\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* CONTROL: scalar i32 (sz==8) — zeroed pre-#16 by the MOVQ $0 arm. */
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{ "scalar_i32",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = { let x: i32; return x; };\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* CONTROL: [20]u8 (>8) — zeroed pre-#16 by the #84 sz>8 run. */
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{ "arr20_u8",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = {\n"
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" let c: [20]u8; let acc: i32 = 0; let j: i32 = 0;\n"
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" for (j < 20) { acc += (c[j]: i32); j += 1; };\n"
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" return acc;\n"
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"};\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* CONTROL: bare str header (24B) — rob's declmod `let empty: str;`
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* shape. .len must read 0 (zeroed pre-#16 by the sz>8 run). */
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{ "str_hdr",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = { let empty: str; return empty.len; };\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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/* CONTROL: bare slice header (24B) — .len must read 0. */
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{ "slice_hdr",
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"package main;\n"
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"fn dirty() void = {\n"
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" let big: [64]u8; let i: i32 = 0;\n"
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" for (i < 64) { big[i] = 222u8; i += 1; };\n"
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"};\n"
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"fn probe() i32 = { let xs: []i32; return xs.len; };\n"
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"export fn main() i32 = { dirty(); return probe(); };\n", 0 },
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{ NULL, NULL, 0 }
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};
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static int
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slurp_eq(const char *a, const char *b)
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{
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FILE *fa = fopen(a, "rb");
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FILE *fb = fopen(b, "rb");
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if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
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int rc = 0;
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for (;;) {
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int ca = fgetc(fa);
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int cb = fgetc(fb);
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if (ca != cb) { rc = -1; break; }
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if (ca == EOF) break;
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}
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fclose(fa); fclose(fb);
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return rc;
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}
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int
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main(void)
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{
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const char *bin = getenv("BIN");
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if (!bin) bin = "out/bin";
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char absbin[1024];
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if (bin[0] != '/') {
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char cwd[1024];
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if (getcwd(cwd, sizeof cwd) == NULL) return 1;
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snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
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bin = absbin;
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}
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char w6c[1100], w6c_ww[1100];
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snprintf(w6c, sizeof w6c, "%s/w6c", bin);
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snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);
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if (access(w6c_ww, X_OK) != 0) {
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fprintf(stderr, "zeroinit: w6c_ww missing — cannot run the "
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"cs==ww byte-id gate\n");
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return 1;
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}
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int n = 0, fail = 0;
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for (int i = 0; rows[i].src; i++, n++) {
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char src[64];
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snprintf(src, sizeof src, "/tmp/wwzi_%d_%d.ww", getpid(), i);
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FILE *f = fopen(src, "wb");
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if (f == NULL) { fail++; continue; }
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fputs(rows[i].src, f);
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fclose(f);
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/* (a) cstage build + run in a scratch dir. */
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char tmpdir[64];
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snprintf(tmpdir, sizeof tmpdir, "/tmp/wwzi_%d_d_%d", getpid(), i);
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mkdir(tmpdir, 0755);
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char cmd[2048];
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snprintf(cmd, sizeof cmd, "cd %s && %s/ww build %s",
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tmpdir, bin, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: cstage build failed\n",
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rows[i].label);
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fail++;
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unlink(src); rmdir(tmpdir);
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continue;
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}
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char outbin[128];
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const char *base = strrchr(src, '/');
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base = base ? base + 1 : src;
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snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
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char *dot = strrchr(outbin, '.');
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if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
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int got = runwait(outbin);
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if (got != rows[i].want_exit) {
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fprintf(stderr, "row[%s]: cstage exit %d, want %d "
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"(bare let read stack garbage?)\n",
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rows[i].label, got, rows[i].want_exit);
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fail++;
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}
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unlink(outbin); rmdir(tmpdir);
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/* (b) cs==ww byte-id gate. */
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char cs_s[64], ws_s[64];
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snprintf(cs_s, sizeof cs_s, "/tmp/wwzi_%d_%d_cs.s", getpid(), i);
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snprintf(ws_s, sizeof ws_s, "/tmp/wwzi_%d_%d_ww.s", getpid(), i);
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snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, cs_s, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c failed\n", rows[i].label);
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fail++; unlink(src); continue;
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}
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snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
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w6c_ww, ws_s, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c_ww failed\n", rows[i].label);
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fail++; unlink(src); unlink(cs_s); continue;
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}
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if (slurp_eq(cs_s, ws_s) != 0) {
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fprintf(stderr, "row[%s]: cstage/wwstage .s DIFFER "
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"(rule-10 byte-id violation)\n", rows[i].label);
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fail++;
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}
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unlink(src); unlink(cs_s); unlink(ws_s);
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}
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if (fail) {
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fprintf(stderr, "%d/%d zeroinit tests failed\n", fail, n);
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return 1;
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}
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printf("zeroinit: %d/%d ok (cstage run + cs==ww byte-id)\n", n, n);
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return 0;
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}
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