selfhost+test: size match-spill slot by scrutinee, not 24B (#9)
wwstage cgmatch hardcoded `spillsz = 24` + unconditional CX write
where cstage emits `slot_size = (su->kind == TY_TAGGED) ? su->size
: 16` with `if (slot_size > 16)` gating. For 1-word-payload variants
like `(*u8 | oserror)` the slot is 16B; wwstage over-allocated and
over-wrote past the receiver's read window.
Factor cgmatch's non-ident scrutinee-type resolution + spill sizing
into matchscrutt + matchspillsz in cgenutil.ww. cgmatch gates CX
write on `spillsz > 16`; R8 gate `> 24` already correct. scanlocals
N_MATCH branch uses the same helpers — scan+emit lockstep.
Test 716: 4 rows × {cstage runtime, wwstage runtime, asm-byte-id}.
Aliased (*u8 | oserror) ok/err arms, raw (*u8 | i64) for hypothesis
breadth, (str | i64) 24B regression guard.
This commit is contained in:
287
test/wcc/716_match_spill_pointer_payload.c
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287
test/wcc/716_match_spill_pointer_payload.c
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@@ -0,0 +1,287 @@
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/*
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* 716_match_spill_pointer_payload — wwstage @match_spill scratch slot
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* sized to the scrutinee's tagged-union slot, not a hardcoded 24B
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* default. Surfaced during task #23 (lib/os path *u8 → str migration)
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* where `kpath` originally returned `(*u8 | oserror)`.
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*
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* Pre-fix (#9): cgmatch's non-ident scrutinee spill defaulted spillsz
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* to 24 and only grew it; cgendecl scanlocals mirrored with a hardcoded
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* `total += 24`. For a 1-word-payload tagged union (`(*u8 | oserror)`
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* with `type oserror = !i64`) the actual slot is 16B (tag + one 8B
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* word) — cstage allocated $48 / 16B slot / 2-word ABI (AX=tag, DX),
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* wwstage allocated $64 / 24B slot / 3-word ABI (AX=tag, DX, CX).
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* Frame-size drift broke bootstrap byte-identity the moment any caller
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* matched on such a return.
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*
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* Fix (#9, wwstage-only per rule 10): factor scrutinee-type resolution
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* into matchscrutt; factor slot-size computation into matchspillsz
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* (default 16, mirroring cmd/w6c/cgen.c cgmatch's `slot_size = (su->
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* kind == TY_TAGGED) ? su->size : 16`). cgmatch gates CX write on
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* `spillsz > 16` (R8 gate `> 24` was already correct). scanlocals
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* uses the same helpers so scan + emit stay lockstep.
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*
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* What this test pins:
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* - Asm byte-identity between cstage and wwstage for the canonical
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* `(*u8 | oserror)` shape (aliased !i64) and the raw `(*u8 | i64)`
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* shape — both must produce $48 frame, 16B spill slot, 2-word
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* return ABI.
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* - Runtime: both arms (pointer / error) round-trip the payload
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* correctly through the narrower spill.
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* - 24B-slot regression guard: `(str | i64)` (max payload 16B, slot
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* 24B) still byte-identical post-fix — the gate must keep the CX
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* write for slot_size > 16.
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*
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* NOT covered: raw `(*u8 | !i64)` (no alias) — wwstage's variant-index
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* resolution for the raw N_TBANG-in-union shape has a separate pre-
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* existing tag-emit divergence from cstage (tag=0 vs tag=1) that is
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* orthogonal to the spill-slot sizing fixed by #9. Documented at the
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* probe .ai/probe_tagged_return_pointer_payload.ww.
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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; };
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static const struct row rows[] = {
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/* 1. Canonical `(*u8 | oserror)` (aliased !i64). Pointer arm
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* returns the first byte through a str-literal `.ptr`. Avoiding
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* a top-level `let buf: [16]u8;` sidesteps an orthogonal wwstage
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* DATAW-emit divergence for module-scope uninit `[N]u8`. */
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{ "ptr_payload_aliased_bang_ok",
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"type oserror = !i64;\n"
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"fn kpath(p: str) (*u8 | oserror) = {\n"
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" if (p.len < 0) { return -36i64: oserror; };\n"
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" let s: str = \"A\";\n"
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" return s.ptr;\n"
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"};\n"
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"fn main() i32 = {\n"
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" let q: str = \"x\";\n"
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" match (kpath(q)) {\n"
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" case let e: oserror => return (e: i64): i32;\n"
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" case let p: *u8 => return p[0]: i32;\n"
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" };\n"
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" return 0;\n"
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"};\n",
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65 },
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/* 2. Same shape, error arm: pre-fix the 24B spill clobbered CX
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* (irrelevant tag-only path) and bumped the frame; this row
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* pins the error arm round-trips -36 + 100 = 64. */
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{ "ptr_payload_aliased_bang_err",
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"type oserror = !i64;\n"
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"fn kpath(p: str) (*u8 | oserror) = {\n"
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" if (p.len >= 0) { return -36i64: oserror; };\n"
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" let s: str = \"A\";\n"
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" return s.ptr;\n"
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"};\n"
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"fn main() i32 = {\n"
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" let q: str = \"x\";\n"
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" match (kpath(q)) {\n"
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" case let e: oserror => return ((e: i64): i32) + 100;\n"
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" case let p: *u8 => return p[0]: i32;\n"
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" };\n"
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" return 0;\n"
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"};\n",
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64 },
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/* 3. Raw `(*u8 | i64)` — no alias, no `!`. Hypothesis (b) probe:
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* the spill-slot fix holds regardless of whether the payload is
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* wrapped in a type alias. */
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{ "ptr_payload_raw_i64_ok",
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"fn kpath(p: str) (*u8 | i64) = {\n"
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" if (p.len < 0) { return -36i64; };\n"
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" let s: str = \"Z\";\n"
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" return s.ptr;\n"
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"};\n"
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"fn main() i32 = {\n"
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" let q: str = \"x\";\n"
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" match (kpath(q)) {\n"
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" case let e: i64 => return e: i32;\n"
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" case let p: *u8 => return p[0]: i32;\n"
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" };\n"
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" return 0;\n"
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"};\n",
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90 },
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/* 4. 24B-slot regression guard. `(str | i64)` slot = 8 tag +
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* 16 str = 24. The CX write at slot+16 is required (carries
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* .len for the str arm). Pre-fix this row passed; post-fix the
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* `spillsz > 16` gate must keep CX. Returns s.len for "hello"
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* = 5. */
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{ "str_payload_24B_keeps_cx",
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"fn pick(b: bool) (str | i64) = {\n"
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" if (b) { return \"hello\"; };\n"
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" return 7i64;\n"
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"};\n"
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"fn main() i32 = {\n"
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" match (pick(true)) {\n"
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" case let e: i64 => return (e: i32) + 200;\n"
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" case let s: str => return s.len: i32;\n"
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" };\n"
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" return 0;\n"
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"};\n",
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5 },
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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/wcmsp_%d_%d.ww", getpid(), i);
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snprintf(tmpdir, sizeof tmpdir, "/tmp/wcmsp_%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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snprintf(cmd, sizeof cmd, "cd %s && %s build %s",
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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 — pin frame size + spill layout by diffing the
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* w6c vs w6c_ww text output. The whole point of #9 is that wwstage's
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* frame stops bloating for 1-word-payload variants, so the bytes
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* must match (modulo orthogonal divergences — none on these rows). */
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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/wcmsp_asm_%d_%d.ww", getpid(), i);
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snprintf(cs, sizeof cs, "/tmp/wcmsp_asm_%d_%d_c.s", getpid(), i);
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snprintf(ws, sizeof ws, "/tmp/wcmsp_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, "%s/w6c -o %s %s 2>/dev/null", 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, "%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[512];
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if (bin[0] != '/') {
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char cwd[256];
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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[640];
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snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
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char wdrv[640];
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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, "match_spill_pointer_payload: 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 got = run_driver(drivers[d].path, &rows[i], i);
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total++;
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if (got != rows[i].want) {
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fprintf(stderr,
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"match_spill_pointer_payload[%s][%s]: exit=%d want=%d\n",
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drivers[d].name, rows[i].label,
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got, rows[i].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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"match_spill_pointer_payload: %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("match_spill_pointer_payload: %d/%d ok\n", total, total);
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return 0;
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}
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Reference in New Issue
Block a user