test: regression lock for struct-ABI size formula (#78 lock)
Project #78 was ken-flagged: cstage folded size(struct{i32,i32,i32}) to 12 (cmd/wcc/check.c:760, `(off + maxalign - 1) & ~(maxalign - 1)`) while wwstage walked a slot-padded fsz ladder and yielded 16. The two checkers ran different layout formulas.d4e500f(#169) closed the cgen ABI half by introducing structabisize and walking it via per- field tinfo.align;39f9267+66a91c8converged the remaining cgen sites that had picked the slot-padded number. Verified at the size(T) fold and the .s byte-id on every layout-edge shape. Add 762_struct_abi_size.c (6 table rows) to lock the closure. Each row carries a (sz, aln) field table; the expected size is computed in C via the Hare layout formula (rule 13: no hardcoded size literals — a formula bump lands in compute_expected and every row tracks). Both gates run per row: a runtime check that `return size(T): i32` matches the computed expected on both stages (catches a fold drift), and a w6c vs w6c_ww .s byte-id (catches a cgen-ABI walker drift even when the fold still matches — the two walkers are independent SSoTs). Rows target maxalign edges: i32_x3_maxalign4 #78 canonical, natural==ABI==12 i32_i32_i64_lead_narrow maxalign 8, narrow lead, ABI 16 i64_i32_i32_sub8_tail #169 sub-8 tail, ABI 16 (the round-up) i16_x3_maxalign2 maxalign 2, natural==ABI==6 i32_i32_i64_mid_align mid-record align step explicit i64_x3_natural_24 all 8-wide, natural==ABI==24 GATE POLARITY: this file must stay GREEN. A red here means eitherd4e500freverted, or one of the two layout walkers (check.c:760 / check.ww:958 / cgen.c struct_arg_size / cgenutil.ww structabisize) drifted from the formula.
This commit is contained in:
7
Makefile
7
Makefile
@@ -312,6 +312,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
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$(BIN)/test_check_enum_fold \
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$(BIN)/test_def_widen_const \
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$(BIN)/test_inferred_struct_arg_push \
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$(BIN)/test_struct_abi_size \
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$(BIN)/test_use_promote_alias \
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$(BIN)/test_field_signed $(BIN)/test_frame_argcount \
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$(BIN)/test_selfhost $(BIN)/test_w6a_ww $(BIN)/test_w6l_ww \
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@@ -591,6 +592,12 @@ $(BIN)/test_inferred_struct_arg_push: test/wcc/761_inferred_struct_arg_push.c \
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$(LIB)/libwwrt.a | $(BIN)
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$(CC) $(CFLAGS) -o $@ $<
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$(BIN)/test_struct_abi_size: test/wcc/762_struct_abi_size.c \
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$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
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$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
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$(LIB)/libwwrt.a | $(BIN)
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$(CC) $(CFLAGS) -o $@ $<
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$(BIN)/test_arrlit_str_full: test/wcc/711_arrlit_str_full.c \
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$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
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$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
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286
test/wcc/762_struct_abi_size.c
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286
test/wcc/762_struct_abi_size.c
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@@ -0,0 +1,286 @@
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/*
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* 762_struct_abi_size — defensive lock for project #78. cstage once
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* folded size(struct{i32,i32,i32}) to 12 while wwstage folded it to
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* 16; the two checkers walked different layout formulas. After
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* d4e500f (#169) introduced structabisize and the cgen ABI sites
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* converged onto a single (off + maxalign - 1) & ~(maxalign - 1)
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* formula on both sides, every layout-edge shape should agree —
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* BOTH at the size(T) fold (cstage check.c:760 / wwstage check.ww
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* astsize N_TSTRUCT) and at the register-RECV/RETURN ABI walker
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* (cgen.c struct_arg_size / structabisize). This probe pins both.
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*
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* The fold and the ABI walker share the formula but live in two
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* different sources: check.c:760 vs check.ww:958 (the language
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* builtin) and cmd/w6c/cgen.c struct_arg_size vs
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* selfhost/cmd/wcc/cgenutil.ww structabisize (the cgen ABI). Either
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* can drift independently — locking only the runtime exit code via
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* size(T) misses an ABI-walker regression that does not change the
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* literal fold; locking only the .s byte-id misses a fold regression
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* the cgen would happily honour. Both gates run per row.
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*
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* Expected size is COMPUTED from a (sz, aln) field table per row,
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* not hardcoded — a stage-internal formula bump (rule 13) lands the
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* change in compute_expected() and every row tracks. The probe must
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* red the moment any source-of-truth drifts from the documented
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* Hare-style layout: align(off, fa); off += fs; size = align(off,
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* maxalign).
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*
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* Shape coverage targets the maxalign edges where the bug class
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* lived:
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* 1. {3xi32} — #78 canonical, maxalign 4, natural 12,
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* ABI 12 (no round-up)
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* 2. {i32,i32,i64} — maxalign 8, narrow lead, ABI 16
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* 3. {i64,i32,i32} — maxalign 8 with sub-8 tail, ABI 16
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* (the #169 round-up case)
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* 4. {3xi16} — maxalign 2, natural 6, ABI 6
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* 5. {2xi32,i64} — maxalign 8 with mid-record alignment
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* padding (f3 must skip to off=8)
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* 6. {3xi64} — maxalign 8, all 8-wide, natural==ABI=24
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*
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* GATE POLARITY: this file must stay GREEN. A red here means either
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* d4e500f (#169 structabisize) reverted, or one of the two layout
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* walkers drifted from the formula.
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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 field { int sz; int aln; };
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struct row {
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const char *label;
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const char *src; /* must `return size(T): i32` */
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int nfields;
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struct field fields[8];
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};
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/* Hare / cstage check.c:701-760 / wwstage check.ww astsize N_TSTRUCT
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* formula. Per CLAUDE.md rule 13 the expected size for each row is
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* derived here, not literalled into the row table. */
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static int
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compute_expected(const struct field *f, int n)
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{
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int off = 0, maxalign = 1;
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for (int i = 0; i < n; i++) {
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int a = f[i].aln;
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if (a > maxalign) maxalign = a;
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off = (off + a - 1) & ~(a - 1);
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off += f[i].sz;
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}
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return (off + maxalign - 1) & ~(maxalign - 1);
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}
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static const struct row rows[] = {
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/* 1. {3xi32} — #78 canonical. cstage check.c:760 returned 12,
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* wwstage formerly walked a slot-padded ladder yielding 16. The
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* fold now uses astsize's (off + maxal - 1) & ~(maxal - 1) on
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* both sides; expect 12. */
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{ "i32_x3_maxalign4",
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"type t = struct { a: i32, b: i32, c: i32 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{4,4},{4,4},{4,4}} },
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/* 2. {i32,i32,i64} — maxalign 8, off lands at 8 before the i64,
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* total 16. */
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{ "i32_i32_i64_lead_narrow",
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"type t = struct { a: i32, b: i32, c: i64 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{4,4},{4,4},{8,8}} },
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/* 3. {i64,i32,i32} — natural extent 16, maxalign 8: the post-
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* field-3 round-up is a no-op here, but the #169 commit added
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* exactly this round-up so the structabisize walker matches
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* cstage on the maxalign-8 sub-8-tail shape (cf. {i64,i32}). */
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{ "i64_i32_i32_sub8_tail",
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"type t = struct { a: i64, b: i32, c: i32 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{8,8},{4,4},{4,4}} },
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/* 4. {3xi16} — maxalign 2, natural 6. Guards against a future
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* "round to 8" shortcut creeping back into either walker. */
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{ "i16_x3_maxalign2",
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"type t = struct { a: i16, b: i16, c: i16 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{2,2},{2,2},{2,2}} },
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/* 5. {2xi32,i64} — f3 must skip off from 8→8 (already aligned)
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* but the row exercises the mid-record align step explicitly;
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* a missing `off = align(off, fa)` would mis-place the i64. */
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{ "i32_i32_i64_mid_align",
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"type t = struct { a: i32, b: i32, c: i64 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{4,4},{4,4},{8,8}} },
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/* 6. {3xi64} — natural==ABI, the maxalign-rounded formula must
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* not double-round. */
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{ "i64_x3_natural_24",
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"type t = struct { a: i64, b: i64, c: i64 };\n"
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"export fn main() i32 = { return size(t): i32; };\n",
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3, {{8,8},{8,8},{8,8}} },
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};
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static int
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run_driver(const char *driver, const struct row *r, int i)
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{
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char src[64], tmpdir[64], cmd[1024];
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snprintf(src, sizeof src, "/tmp/wcabi_%d_%d.ww", getpid(), i);
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snprintf(tmpdir, sizeof tmpdir, "/tmp/wcabi_%d_d_%d", getpid(), i);
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FILE *f = fopen(src, "wb");
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if (!f) return -1;
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fputs(r->src, f);
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fclose(f);
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mkdir(tmpdir, 0755);
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/* timeout 180 per repo convention (cf. 760, 761); test/run does
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* not bound individual binaries. */
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snprintf(cmd, sizeof cmd, "cd %s && timeout 180 %s build %s 2>/dev/null",
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tmpdir, driver, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: build via %s failed\n",
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r->label, driver);
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unlink(src); rmdir(tmpdir);
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return -1;
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}
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const char *base = strrchr(src, '/');
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base = base ? base + 1 : src;
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char outbin[128];
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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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unlink(src); unlink(outbin); rmdir(tmpdir);
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return got;
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}
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/* asm_byte_identical — diff w6c vs w6c_ww text output. The cgen ABI
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* walker (structabisize since #169 / d4e500f) feeds the struct-
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* return + struct-arg push widths; a divergence on these shapes
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* surfaces as a .s difference even when the size(T) fold still
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* matches (the two walkers are independent SSoTs). */
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static int
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asm_byte_identical(const char *bin, const struct row *r, int i)
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{
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char src[64], cs[64], ws[64], cmd[1024];
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snprintf(src, sizeof src, "/tmp/wcabi_asm_%d_%d.ww", getpid(), i);
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snprintf(cs, sizeof cs, "/tmp/wcabi_asm_%d_%d_c.s", getpid(), i);
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snprintf(ws, sizeof ws, "/tmp/wcabi_asm_%d_%d_w.s", getpid(), i);
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FILE *f = fopen(src, "wb");
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if (!f) return -1;
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fputs(r->src, f);
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fclose(f);
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snprintf(cmd, sizeof cmd, "timeout 180 %s/w6c -o %s %s 2>/dev/null",
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bin, cs, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c errored\n", r->label);
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unlink(src);
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return -1;
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}
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snprintf(cmd, sizeof cmd, "timeout 180 %s/w6c_ww -o %s %s 2>/dev/null",
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bin, ws, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label);
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unlink(src); unlink(cs);
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return -1;
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}
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FILE *fc = fopen(cs, "rb");
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FILE *fw = fopen(ws, "rb");
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int rc = 0;
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if (!fc || !fw) {
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rc = -1;
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} else {
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for (;;) {
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int a = fgetc(fc);
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int b = fgetc(fw);
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if (a != b) { rc = -1; break; }
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if (a == EOF) break;
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}
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}
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if (fc) fclose(fc);
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if (fw) fclose(fw);
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if (rc != 0)
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fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n",
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r->label);
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unlink(src); unlink(cs); unlink(ws);
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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 cdrv[1024];
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snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
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char wdrv[1024];
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snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
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struct { const char *name; const char *path; int gated_on_existence; }
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drivers[] = {
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{ "cstage", cdrv, 0 },
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{ "wwstage", wdrv, 1 },
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{ NULL, NULL, 0 },
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};
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int n = (int)(sizeof rows / sizeof rows[0]);
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int total = 0, fail = 0;
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for (int d = 0; drivers[d].name; d++) {
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if (drivers[d].gated_on_existence
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&& access(drivers[d].path, X_OK) != 0) {
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fprintf(stderr, "struct_abi_size: skip %s (no %s)\n",
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drivers[d].name, drivers[d].path);
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continue;
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}
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for (int i = 0; i < n; i++) {
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int want = compute_expected(rows[i].fields,
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rows[i].nfields);
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int got = run_driver(drivers[d].path, &rows[i], i);
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total++;
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if (got != want) {
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fprintf(stderr,
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"struct_abi_size[%s][%s]: size=%d want=%d\n",
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drivers[d].name, rows[i].label,
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got, want);
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fail++;
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}
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}
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}
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if (access(wdrv, X_OK) == 0) {
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for (int i = 0; i < n; i++) {
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total++;
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if (asm_byte_identical(bin, &rows[i], i) != 0)
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fail++;
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}
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}
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if (fail) {
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fprintf(stderr,
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"struct_abi_size: %d/%d fixtures failed\n",
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fail, total);
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return 1;
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}
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printf("struct_abi_size: %d/%d ok\n", total, total);
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return 0;
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}
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