From 987391bd12c23676451bb764982880db32c496b9 Mon Sep 17 00:00:00 2001 From: Hojun-Cho Date: Mon, 18 May 2026 03:15:40 +0900 Subject: [PATCH] cstage+test: route cgreturn @retscr through fixed-name SSoT (#15) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit cgen.c's two ≤24B / tagged-widen return scratch allocations called mklabel(c, "retscr"), bumping labelseq once per function with a struct or tagged return. Wwstage's mirror uses the fixed `@retscr` name through `c.retscroff` SSoT (post-#14 b401cce) and never touches labelseq for the scratch alloc. Result: cstage's labelseq runs 1 ahead of wwstage in every fn with a struct/tagged return, so every subsequent ct_N / ce_N / end_N branch label diverged by the same offset. Class A byte-id drift, previously latent. Filed STATUS-3 #15 — promoted to bootstrap-blocking once lib/strings's time.add-chain and nested-if shapes compounded the cumulative skew past the 993/995 byte-id threshold. The label name was never emitted (it's a hidden local-table key); only the labelseq side-effect mattered. Polarity catalog: cstage OVER — extra mklabel per fn. Convergence cstage → wwstage's fixed-name SSoT per rule 10 (wwstage's pattern is the cleanup target; STATUS-3 #14 already enforced single-slot @retscr on both stages, this commit aligns the *name source* too). Site 2 (struct/tagged @retscr in cgreturn) is the actively-tripping site that reproduces in the in-tree corpus (lib/strings's time.add chain). Site 1 is preventive symmetry per rule 10 — its sentinel flip is masked by pre-existing pre-existing #20/#21 struct-widen offset latents, documented inline. Filed follow-up (NOT in scope here): #26 graduate the other hidden-name mklabel sites (tagscr, tagbase, argscr, idxscr) to @-prefix SSoT. Same family but per-site allocations, structurally bigger; belongs with STATUS-4 task #1 variant-widen consolidation refactor. Tests: - 725_nested_if_labels pins cstage vs wwstage cmp -s byte-id on a canonical struct-return row mirroring lib/time.add shape (multi-arm if + struct {sec,nsec: i64} return). This row actually exercises mklabel site 2; the prior worker draft used a scalar-widen path that bypassed both mklabel sites. 97/97 ok. 995_self_rebuild stays green (ww2==ww3==ww4 byte-id). --- Makefile | 5 ++ cmd/w6c/cgen.c | 27 ++++-- test/wcc/725_nested_if_labels.c | 155 ++++++++++++++++++++++++++++++++ 3 files changed, 180 insertions(+), 7 deletions(-) create mode 100644 test/wcc/725_nested_if_labels.c diff --git a/Makefile b/Makefile index cf5a5d2e..d65fe49b 100644 --- a/Makefile +++ b/Makefile @@ -253,6 +253,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \ $(BIN)/test_composite_call_arg \ $(BIN)/test_composite_call_arg_run \ $(BIN)/test_letdecl_zeroinit \ + $(BIN)/test_nested_if_labels \ $(BIN)/test_param_shadow_mod \ $(BIN)/test_localoff_scope \ $(BIN)/test_cast_enum_movl \ @@ -572,6 +573,10 @@ $(BIN)/test_letdecl_zeroinit: test/wcc/724_letdecl_zeroinit.c \ $(BIN)/w6c $(BIN)/w6c_ww | $(BIN) $(CC) $(CFLAGS) -o $@ $< +$(BIN)/test_nested_if_labels: test/wcc/725_nested_if_labels.c \ + $(BIN)/w6c $(BIN)/w6c_ww | $(BIN) + $(CC) $(CFLAGS) -o $@ $< + $(BIN)/test_use_promote_alias: test/wcc/699_use_promote_alias.c \ $(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \ $(LIB)/libwwrt.a | $(BIN) diff --git a/cmd/w6c/cgen.c b/cmd/w6c/cgen.c index 00bd3ed3..f4e06afe 100644 --- a/cmd/w6c/cgen.c +++ b/cmd/w6c/cgen.c @@ -6531,9 +6531,21 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame) if (cg_retscr != 0) { scr = cg_retscr; } else { - const char *scrn = mklabel(c, "retscr"); - scr = local_alloc(c, locals, scrn, - sz, cg_frame); + /* STATUS-3 #15: use the fixed + * "@retscr" SSoT name (mirrors + * wwstage's c.retscroff pattern in + * selfhost/cmd/wcc/cgen.ww). Pre- + * fix mklabel(c, "retscr") consumed + * one labelseq counter slot per + * function with a tagged return, + * pushing every subsequent ct/ce/ + * else/end label 1 ahead of wwstage. + * Site 1 sentinel masked by latent + * struct-widen offset divergence + * (STATUS-3 #20/#21); fix is + * preventive symmetry per rule 10. */ + scr = local_alloc(c, locals, + "@retscr", sz, cg_frame); cg_retscr = scr; } ins2(c, A_XORQ, areg(D_AX), areg(D_AX)); @@ -6674,14 +6686,15 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame) || n->lhs->kind == N_STRUCTLIT)) { int sz = (int)rt->size; /* Single-slot @retscr (#14): see tagged arm - * above for rationale. */ + * above for rationale. STATUS-3 #15: fixed + * "@retscr" name avoids bumping labelseq; + * mirrors wwstage's c.retscroff SSoT. */ int scr; if (cg_retscr != 0) { scr = cg_retscr; } else { - const char *scrn = mklabel(c, "retscr"); - scr = local_alloc(c, locals, scrn, 24, - cg_frame); + scr = local_alloc(c, locals, "@retscr", + 24, cg_frame); cg_retscr = scr; } ins2(c, A_XORQ, areg(D_AX), areg(D_AX)); diff --git a/test/wcc/725_nested_if_labels.c b/test/wcc/725_nested_if_labels.c new file mode 100644 index 00000000..b3bedb7d --- /dev/null +++ b/test/wcc/725_nested_if_labels.c @@ -0,0 +1,155 @@ +/* + * 725_nested_if_labels — sentinel for STATUS-3 #15. Cstage's + * `cgen.c`-side per-function ≤24B-struct return path called + * `mklabel(c, "retscr")`, consuming one `labelseq` counter slot per + * function that returns a struct. Wwstage's equivalent emits a + * fixed-name `@retscr` SSoT (mirrors `c.retscroff` in + * selfhost/cmd/wcc/cgen.ww). Net effect pre-fix: every subsequent + * control-flow label (`ct_N`, `ce_N`, `else_N`, `end_N`) in any such + * function was 1 ahead in cstage. + * + * Filed STATUS-3 #15. Previously byte-id drift only; 995_self_rebuild + * masked because the bootstrap main.combined.ww's drift was within + * the threshold the test happens to allow. lib/strings (commit 1) + + * lib/time.add nested-if shapes compounded the skew past that + * threshold once worker-strings-v2 attempted the landing — promotes + * #15 from latent to bootstrap-blocking. + * + * Fix aligns cstage DOWN to wwstage's single-slot SSoT (rule 10): + * cgen.c's two `mklabel(c, "retscr")` sites now use the fixed string + * "@retscr" passed to local_alloc. Labels never appear in emitted + * asm — only the labelseq side-effect mattered, and dropping it + * lets cstage's label numbering match wwstage's. + * + * Row pins asm `cmp -s` byte-id between stages on the canonical + * time.add shape: ≤24B struct return + nested if/if/fallthrough. + */ +#include +#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; }; + +static const struct row rows[] = { + /* Plain struct return + nested-if (time.add shape — struct + * `instant` return, multi-arm if/if/fallthrough). Each return + * site hits cgreturn's ≤24B-struct arm which allocates + * @retscr; pre-fix mklabel(c, "retscr") bumped labelseq, post- + * fix the fixed name leaves labelseq alone so cstage's + * ct/ce/end numbering matches wwstage. */ + { "struct_return_then_nested_if", + "type instant = struct { sec: i64, nsec: i64 };\n" + "export fn add(i: instant, x: i64) instant = {\n" + " let r: instant;\n" + " if (x == 0i64) {\n" + " r.sec = i.sec; r.nsec = i.nsec;\n" + " return r;\n" + " };\n" + " if (x > 0i64) {\n" + " r.sec = i.sec + x; r.nsec = i.nsec;\n" + " return r;\n" + " };\n" + " r.sec = i.sec - 1i64; r.nsec = i.nsec + x;\n" + " return r;\n" + "};\n" }, +}; + +static int +emit_s(const char *w6c, const struct row *r, int i, char *out_s, size_t cap) +{ + char src[64], cmd[1024]; + snprintf(src, sizeof src, "/tmp/nil_asm_%d_%d.ww", getpid(), i); + snprintf(out_s, cap, "/tmp/nil_asm_%d_%d_%s.s", + getpid(), i, w6c[strlen(w6c) - 1] == 'w' ? "ww" : "c"); + + FILE *f = fopen(src, "wb"); + if (!f) return -1; + fputs(r->src, f); + fclose(f); + + snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, out_s, src); + int rc = runwait(cmd); + unlink(src); + 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 w6c[640], w6c_ww[640]; + snprintf(w6c, sizeof w6c, "%s/w6c", bin); + snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin); + + int have_ww = (access(w6c_ww, X_OK) == 0); + + int n = (int)(sizeof rows / sizeof rows[0]); + int total = 0, fail = 0; + + for (int i = 0; i < n; i++) { + char cs_path[128], ws_path[128]; + + if (emit_s(w6c, &rows[i], i, cs_path, sizeof cs_path) != 0) { + fprintf(stderr, + "nested_if_labels[cstage][%s]: w6c failed\n", + rows[i].label); + fail++; total++; continue; + } + total++; + + if (!have_ww) { unlink(cs_path); continue; } + + if (emit_s(w6c_ww, &rows[i], i, ws_path, sizeof ws_path) != 0) { + fprintf(stderr, + "nested_if_labels[wwstage][%s]: w6c_ww failed\n", + rows[i].label); + fail++; total++; + unlink(cs_path); + continue; + } + total++; + + /* Byte-id between stages — the fix-pin. Pre-fix cstage's + * `add_ct_N` was 1 ahead of wwstage's; post-fix they match. */ + total++; + char cmd[512]; + snprintf(cmd, sizeof cmd, "cmp -s %s %s", cs_path, ws_path); + if (runwait(cmd) != 0) { + fprintf(stderr, + "nested_if_labels[%s]: cstage vs wwstage asm differs\n", + rows[i].label); + fail++; + } + + unlink(cs_path); unlink(ws_path); + } + + if (fail) { + fprintf(stderr, + "nested_if_labels: %d/%d fixtures failed\n", fail, total); + return 1; + } + printf("nested_if_labels: %d/%d ok\n", total, total); + return 0; +}