/* * 989_ffivariadic_run — C1 (catB-54): a ww caller of a C variadic function * (`@symbol("f") fn f(a: i64, ...) f64;`) must set the SysV AL register to * the number of XMM regs used to pass the variadic FLOAT args. The C callee * gates its xmm-save-area stores on `test %al,%al`, so a wrong AL makes * va_arg(double) read garbage. * * THE BUG (cat-A silent miscompile, byte-id-blind): cgen.c hardcoded AL=0 * (`XORQ AX,AX`) at the variadic-call site — correct only for a zero-float * variadic call. THE FIX: emit AL = the XMM cursor `fi` (the count of float * args placed in XMM regs). Ref SysV §3.5.7, ref/qbe/amd64/sysv.c:384. * * RUNTIME gate (byte-id can never see AL correctness): each row builds a ww * caller that calls the C fixture `double fixture(long n, ...)` (a * va_arg(double) summer, test/wcc/data/ffivariadic/fixture.c, linked from * libffifix.a) and asserts the returned sum. Runs on BOTH the cstage `ww` * and wwstage `ww_ww` drivers (C2): AL is byte-id-blind, so a wwstage fi / * f32-promotion divergence is caught only by a wrong runtime sum here. * * NON-VACUITY DEVIATION (reported to lead): the spec's `fixture(2,1.0,2.0)` * is VACUOUS on this box — with AL=0 the two skipped xmm slots happen to * alias stale stack that already holds 1.0/2.0, so the 2-float call returns * the correct 3.0 even unfixed. At 3+ floats the coincidence breaks: AL=0 * deterministically returns the wrong sum. Every row below uses >=3 floats, * so reverting the fix to `XORQ AX,AX` FAILS this test (proven). A 2-float * row would pass both ways and prove nothing. */ #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; int want_exit; /* 0 == sum matched */ }; static const struct row rows[] = { /* 3 floats: 1+2+3 == 6. The smallest non-vacuous count (see header). */ { "three", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let r: f64 = fixture(3, 1.0, 2.0, 3.0);\n" " if (r == 6.0) { return 0; };\n" " return 1;\n" "};\n", 0 }, /* 5 floats, fewer than the 8 XMM arg regs: 1+2+3+4+5 == 15. */ { "five", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let r: f64 = fixture(5, 1.0, 2.0, 3.0, 4.0, 5.0);\n" " if (r == 15.0) { return 0; };\n" " return 1;\n" "};\n", 0 }, /* 8 floats == all XMM arg regs (AL caps at 8): 1+..+8 == 36. */ { "eight", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let r: f64 = fixture(8, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0);\n" " if (r == 36.0) { return 0; };\n" " return 1;\n" "};\n", 0 }, /* 3 f32 args (#14): C default arg promotion widens each to f64, so * the callee's va_arg(double) reads 1.5+2.5+3.0 == 7.0. Values are * exact in f32, so the f64 compare is exact. Unpromoted (MOVSS, 4B) * the high 4B of each 8B slot is stale stack, so va_arg(double) * pulls garbage and the sum misses 7.0 — this row FAILS pre-fix. */ { "f32three", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let r: f64 = fixture(3, 1.5: f32, 2.5: f32, 3.0: f32);\n" " if (r == 7.0) { return 0; };\n" " return 1;\n" "};\n", 0 }, /* Sharper than f32three: 0.1 is INEXACT in f32, so the f32-rounded * value differs from the f64 literal 0.1. The expected side `(x: f64)` * is the SAME f32 var widened at runtime (CVTSS2SD), so equality holds * iff the variadic arg carried the f32-rounded value promoted to f64 — * NOT the original f64 literal and NOT stale-high-bit garbage. Both a * no-promote (MOVSS) and a hypothetical direct-f64 pass would miss it. * Single f32 arg also exercises the fi==1 boundary. */ { "f32inexact", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let x: f32 = 0.1: f32;\n" " let r: f64 = fixture(1, x);\n" " if (r == (x: f64)) { return 0; };\n" " return 1;\n" "};\n", 0 }, /* Mixed f32 + f64 in one variadic call: only the f32 args (1.5, 3.5) * promote; the f64 arg (2.0) passes at its native width and must NOT be * double-promoted or skewed. 1.5+2.0+3.5 == 7.0, exact in both widths. */ { "f32mixed", "package main;\n" "@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n" "export fn main() int = {\n" " let r: f64 = fixture(3, 1.5: f32, 2.0, 3.5: f32);\n" " if (r == 7.0) { return 0; };\n" " return 1;\n" "};\n", 0 }, }; /* run_build — build+run `src` via cstage `driver`, linking libffifix.a from * `libdir`. Returns the binary's exit code, or -1 on a build failure. */ static int run_build(const char *driver, const char *libdir, const struct row *r, int i) { char src[128], tmpdir[64], outbin[128], work[160], cmd[1024]; snprintf(tmpdir, sizeof tmpdir, "/tmp/ffivar_%d_%d", getpid(), i); if (mkdir(tmpdir, 0755) != 0) { perror(tmpdir); return -2; } snprintf(src, sizeof src, "%s/ffivar_%d_%d.ww", tmpdir, getpid(), i); snprintf(outbin, sizeof outbin, "%s/out", tmpdir); int result = -2, cleanfail = 0; FILE *f = fopen(src, "wb"); if (!f) { perror(src); goto cleanup; } int werr = fputs(r->src, f) == EOF; if (fclose(f) != 0) werr = 1; if (werr) { perror(src); goto cleanup; } /* explicit -o so both the binary and out.sepwork land INSIDE tmpdir */ snprintf(cmd, sizeof cmd, "%s build -L%s -lffifix -o %s %s 2>/dev/null", driver, libdir, outbin, src); int brc = runwait(cmd); int got = -1; if (brc == 0) got = runwait(outbin); result = brc == 0 ? got : -1; cleanup: if (unlink(src) != 0 && errno != ENOENT) { perror(src); cleanfail = 1; } if (unlink(outbin) != 0 && errno != ENOENT) { perror(outbin); cleanfail = 1; } snprintf(work, sizeof work, "%s.sepwork", outbin); snprintf(cmd, sizeof cmd, "rm -rf %s", work); if (runwait(cmd) != 0) { fprintf(stderr, "ffivariadic[%s]: cleanup failed: %s\n", r->label, work); cleanfail = 1; } if (rmdir(tmpdir) != 0) { perror(tmpdir); cleanfail = 1; } if (cleanfail) { fprintf(stderr, "ffivariadic[%s]: temporary cleanup failed\n", r->label); if (result == r->want_exit) result = -2; } return result; } int main(void) { const char *bin = getenv("BIN"); if (!bin) bin = "out/bin"; char absbin[1024]; if (bin[0] != '/') { char cwd[1024]; if (getcwd(cwd, sizeof cwd) == NULL) return 1; snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin); bin = absbin; } char cdrv[1024], wdrv[1024], libdir[1024]; snprintf(cdrv, sizeof cdrv, "%s/ww", bin); snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin); /* libffifix.a lives beside $(BIN) under $(OUT)/ffivariadic — the * Makefile builds it there as a prereq of this test binary. */ snprintf(libdir, sizeof libdir, "%s/../ffivariadic", bin); /* C2: run each row on BOTH the cstage `ww` and the wwstage `ww_ww` * driver. AL correctness is byte-id-blind, so a wwstage fi/promotion * divergence is invisible to the 990-997 gates but caught here as a * wrong sum (nonzero exit). wwstage is access-gated like the other * dual-stage runtime tests (989_chainidx_run) so a cstage-only tree * still runs the cstage rows. */ struct { const char *name; const char *drv; int gated; } 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 && access(drivers[d].drv, X_OK) != 0) { fprintf(stderr, "ffivariadic: skip %s (no %s)\n", drivers[d].name, drivers[d].drv); continue; } for (int i = 0; i < n; i++) { total++; int got = run_build(drivers[d].drv, libdir, &rows[i], i); if (got != rows[i].want_exit) { fprintf(stderr, "ffivariadic[%s][%s]: exit=%d want=%d\n", drivers[d].name, rows[i].label, got, rows[i].want_exit); fail++; } } } if (fail) { fprintf(stderr, "ffivariadic: %d/%d fixtures failed\n", fail, total); return 1; } printf("ffivariadic: %d/%d ok\n", total, total); return 0; }