/* * 716_match_spill_pointer_payload — wwstage @match_spill scratch slot * sized to the scrutinee's tagged-union slot, not a hardcoded 24B * default. Surfaced during task #23 (lib/os path *u8 → str migration) * where `kpath` originally returned `(*u8 | oserror)`. * * Pre-fix (#9): cgmatch's non-ident scrutinee spill defaulted spillsz * to 24 and only grew it; cgendecl scanlocals mirrored with a hardcoded * `total += 24`. For a 1-word-payload tagged union (`(*u8 | oserror)` * with `type oserror = !i64`) the actual slot is 16B (tag + one 8B * word) — cstage allocated $48 / 16B slot / 2-word ABI (AX=tag, DX), * wwstage allocated $64 / 24B slot / 3-word ABI (AX=tag, DX, CX). * Frame-size drift broke bootstrap byte-identity the moment any caller * matched on such a return. * * Fix (#9, wwstage-only per rule 10): factor scrutinee-type resolution * into matchscrutt; factor slot-size computation into matchspillsz * (default 16, mirroring cmd/w6c/cgen.c cgmatch's `slot_size = (su-> * kind == TY_TAGGED) ? su->size : 16`). cgmatch gates CX write on * `spillsz > 16` (R8 gate `> 24` was already correct). scanlocals * uses the same helpers so scan + emit stay lockstep. * * What this test pins: * - Asm byte-identity between cstage and wwstage for the canonical * `(*u8 | oserror)` shape (aliased !i64) and the raw `(*u8 | i64)` * shape — both must produce $48 frame, 16B spill slot, 2-word * return ABI. * - Runtime: both arms (pointer / error) round-trip the payload * correctly through the narrower spill. * - 24B-slot regression guard: `(str | i64)` (max payload 16B, slot * 24B) still byte-identical post-fix — the gate must keep the CX * write for slot_size > 16. * * NOT covered: raw `(*u8 | !i64)` (no alias) — wwstage's variant-index * resolution for the raw N_TBANG-in-union shape has a separate pre- * existing tag-emit divergence from cstage (tag=0 vs tag=1) that is * orthogonal to the spill-slot sizing fixed by #9. Documented at the * probe .ai/probe_tagged_return_pointer_payload.ww. */ #include #include #include #include #include static int runwait(const char *cmd) { int rc = system(cmd); if (rc == -1) return -1; if (WIFEXITED(rc)) return WEXITSTATUS(rc); return -1; } struct row { const char *label; const char *src; int want; }; static const struct row rows[] = { /* 1. Canonical `(*u8 | oserror)` (aliased !i64). Pointer arm * returns the first byte through a str-literal `.ptr`. Avoiding * a top-level `let buf: [16]u8;` sidesteps an orthogonal wwstage * DATAW-emit divergence for module-scope uninit `[N]u8`. */ { "ptr_payload_aliased_bang_ok", "type oserror = !i64;\n" "fn kpath(p: str) (*u8 | oserror) = {\n" " if (p.len < 0) { return -36i64: oserror; };\n" " let s: str = \"A\";\n" " return s.ptr;\n" "};\n" "fn main() i32 = {\n" " let q: str = \"x\";\n" " match (kpath(q)) {\n" " case let e: oserror => return (e: i64): i32;\n" " case let p: *u8 => return p[0]: i32;\n" " };\n" " return 0;\n" "};\n", 65 }, /* 2. Same shape, error arm: pre-fix the 24B spill clobbered CX * (irrelevant tag-only path) and bumped the frame; this row * pins the error arm round-trips -36 + 100 = 64. */ { "ptr_payload_aliased_bang_err", "type oserror = !i64;\n" "fn kpath(p: str) (*u8 | oserror) = {\n" " if (p.len >= 0) { return -36i64: oserror; };\n" " let s: str = \"A\";\n" " return s.ptr;\n" "};\n" "fn main() i32 = {\n" " let q: str = \"x\";\n" " match (kpath(q)) {\n" " case let e: oserror => return ((e: i64): i32) + 100;\n" " case let p: *u8 => return p[0]: i32;\n" " };\n" " return 0;\n" "};\n", 64 }, /* 3. Raw `(*u8 | i64)` — no alias, no `!`. Hypothesis (b) probe: * the spill-slot fix holds regardless of whether the payload is * wrapped in a type alias. */ { "ptr_payload_raw_i64_ok", "fn kpath(p: str) (*u8 | i64) = {\n" " if (p.len < 0) { return -36i64; };\n" " let s: str = \"Z\";\n" " return s.ptr;\n" "};\n" "fn main() i32 = {\n" " let q: str = \"x\";\n" " match (kpath(q)) {\n" " case let e: i64 => return e: i32;\n" " case let p: *u8 => return p[0]: i32;\n" " };\n" " return 0;\n" "};\n", 90 }, /* 4. 24B-slot regression guard. `(str | i64)` slot = 8 tag + * 16 str = 24. The CX write at slot+16 is required (carries * .len for the str arm). Pre-fix this row passed; post-fix the * `spillsz > 16` gate must keep CX. Returns s.len for "hello" * = 5. */ { "str_payload_24B_keeps_cx", "fn pick(b: bool) (str | i64) = {\n" " if (b) { return \"hello\"; };\n" " return 7i64;\n" "};\n" "fn main() i32 = {\n" " match (pick(true)) {\n" " case let e: i64 => return (e: i32) + 200;\n" " case let s: str => return s.len: i32;\n" " };\n" " return 0;\n" "};\n", 5 }, }; static int run_driver(const char *driver, const struct row *r, int i) { char src[128], tmpdir[64], outbin[128], rmcmd[160], cmd[1024]; snprintf(tmpdir, sizeof tmpdir, "/tmp/wcmsp_%d_d_%d", getpid(), i); mkdir(tmpdir, 0755); snprintf(src, sizeof src, "%s/wcmsp_%d_%d.ww", tmpdir, getpid(), i); snprintf(outbin, sizeof outbin, "%s/wcmsp_%d_%d", tmpdir, getpid(), i); snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir); FILE *f = fopen(src, "wb"); if (!f) { runwait(rmcmd); return -1; } fputs(r->src, f); fclose(f); snprintf(cmd, sizeof cmd, "%s build -o %s %s", driver, outbin, src); if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: build via %s failed\n", r->label, driver); runwait(rmcmd); return -1; } int got = runwait(outbin); runwait(rmcmd); return got; } /* asm_byte_identical — pin frame size + spill layout by diffing the * w6c vs w6c_ww text output. The whole point of #9 is that wwstage's * frame stops bloating for 1-word-payload variants, so the bytes * must match (modulo orthogonal divergences — none on these rows). */ static int asm_byte_identical(const char *bin, const struct row *r, int i) { char src[64], cs[64], ws[64], cmd[1024]; snprintf(src, sizeof src, "/tmp/wcmsp_asm_%d_%d.ww", getpid(), i); snprintf(cs, sizeof cs, "/tmp/wcmsp_asm_%d_%d_c.s", getpid(), i); snprintf(ws, sizeof ws, "/tmp/wcmsp_asm_%d_%d_w.s", getpid(), i); FILE *f = fopen(src, "wb"); if (!f) return -1; fputs(r->src, f); fclose(f); snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s 2>/dev/null", bin, cs, src); if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c errored\n", r->label); unlink(src); return -1; } snprintf(cmd, sizeof cmd, "%s/w6c_ww -o %s %s 2>/dev/null", bin, ws, src); if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label); unlink(src); unlink(cs); return -1; } FILE *fc = fopen(cs, "rb"); FILE *fw = fopen(ws, "rb"); int rc = 0; if (!fc || !fw) { rc = -1; } else { for (;;) { int a = fgetc(fc); int b = fgetc(fw); if (a != b) { rc = -1; break; } if (a == EOF) break; } } if (fc) fclose(fc); if (fw) fclose(fw); if (rc != 0) fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n", r->label); unlink(src); unlink(cs); unlink(ws); return rc; } int main(void) { const char *bin = getenv("BIN"); if (!bin) bin = "out/bin"; char absbin[512]; if (bin[0] != '/') { char cwd[256]; if (getcwd(cwd, sizeof cwd) == NULL) return 1; snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin); bin = absbin; } char cdrv[640]; snprintf(cdrv, sizeof cdrv, "%s/ww", bin); char wdrv[640]; snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin); struct { const char *name; const char *path; int gated_on_existence; } drivers[] = { { "cstage", cdrv, 0 }, { "wwstage", wdrv, 1 }, { NULL, NULL, 0 }, }; int n = (int)(sizeof rows / sizeof rows[0]); int total = 0, fail = 0; for (int d = 0; drivers[d].name; d++) { if (drivers[d].gated_on_existence && access(drivers[d].path, X_OK) != 0) { fprintf(stderr, "match_spill_pointer_payload: skip %s (no %s)\n", drivers[d].name, drivers[d].path); continue; } for (int i = 0; i < n; i++) { int got = run_driver(drivers[d].path, &rows[i], i); total++; if (got != rows[i].want) { fprintf(stderr, "match_spill_pointer_payload[%s][%s]: exit=%d want=%d\n", drivers[d].name, rows[i].label, got, rows[i].want); fail++; } } } if (access(wdrv, X_OK) == 0) { for (int i = 0; i < n; i++) { total++; if (asm_byte_identical(bin, &rows[i], i) != 0) fail++; } } if (fail) { fprintf(stderr, "match_spill_pointer_payload: %d/%d fixtures failed\n", fail, total); return 1; } printf("match_spill_pointer_payload: %d/%d ok\n", total, total); return 0; }