ww/test/wcc/937_str_arrfield_store_cap_run.c

/*
 * 937_str_arrfield_store_cap_run — runtime coverage for the G1 fold: STORING a
 * str into a FIELD of an INDEXED element `arr[i].f = v` must write the full 24B
 * {ptr,len,cap} header, not just {ptr,len}. str is 24B since Phase 2 (#1); the
 * write-side mirror of the landed arrfield READ (936) previously stored only 2
 * words (AX=ptr@foff+0, BX=len@foff+8) and silently DROPPED cap.
 *
 * This is only meaningful now that the arrfield READ is 3-word (936): before
 * that fix the store+read were 2-word-symmetric and cap was untouched at both
 * ends, so a dropped store-cap was invisible. Now the read returns the real
 * +16 word, so a 2-word store is observable.
 *
 * Sites: cgen.c's `arr[i].field = v` str branch (N_DOT lhs, N_INDEX lhs.lhs,
 * N_IDENT idxbase) and the cgenexpr.ww cgassign twin. The composed mechanic:
 * the rhs str leaves AX=ptr/BX=len/CX=cap, all three spilled across the
 * index/address computation (the index scale `MOVQ $esz, CX; IMULQ` would
 * clobber cap), the element address staged in DX off the str AX/BX/CX
 * convention (mirroring the s.f=v store), then the full triple stored at
 * foff+0/+8/+16.
 *
 * Rows mirror the 936 arrfield READ rows:
 *   A  [N]S  local array  : `arr[i].f = v`  (LEAQ base, value element).
 *   B  []S   local slice  : `sl[i].f = v`   (MOVQ slice.ptr base, value elem).
 *   D  [N]*S pointer-elem : `arr[i].f = v`  (LEAQ base, MOVQ deref to the *S).
 *
 * RHS cap!=len: each test str is a literal whose .cap is mutated to a value
 * DISTINCT from its len (NOT a bare literal — literals carry cap==len, which
 * would hide a dropped cap; #12: global literal .cap reads 0). cap and len are
 * both nonzero and unequal so a 2-word store that drops cap is detectable.
 *
 * PRE-POISON (B != A, both nonzero, != len): before the G1 store under test,
 * all three slot words are seeded with a DIFFERENT str (ptr='q', len=4,
 * cap=5=A) via a PROVEN already-3-word store path — never the G1 store itself
 * (if G1 is broken its own poison write would also drop cap, leaving +16
 * uninit rather than a controlled poison). A/B poison via `&arr[i]` + a
 * *struct field store (`pr.f = q`); D poisons the pointee via the proven
 * s1local field store (`st.f = q`). The G1 store then writes the test str
 * (ptr='h', len=2, cap=8=B). A broken 2-word store never touches +16, so the
 * 3-word read-back observes the poison cap 5, never 8 — deterministic
 * discrimination with no reliance on a stale register.
 *
 * FULL-TRIPLE ASSERT: a register-reallocation slip in the 3-word store could
 * clobber ptr or len while wiring cap, and a cap-only assert would miss it. So
 * each row reads the value back (landed 3-word arrfield read) and checks all
 * three words: ptr (first byte through it — 'h'=104), len (2), cap (8). The
 * 2-word store writes ptr/len correctly (they ARE the two words it keeps), so
 * cap is the fail-before discriminator; ptr/len guard the fix.
 *
 * Verified fail-before (stashed the store edit on BOTH stages → all rows exit
 * 1, cap reads the poison 5) / pass-after (exit 0), both the cstage `ww` and
 * wwstage `ww_ww` drivers.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>

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[] = {
	/* A — `arr[i].f = v` into a [N]S local array (LEAQ base, value
	 * element). Poison the slot (cap=5,len=4,'q') via &arr[1] + a
	 * *struct field store; then the G1 store lands the test str
	 * (cap=8,len=2,'h'). */
	{ "arrfield_store_array_value",
	  "type rec = struct { f: str };\n"
	  "export fn main() i32 = {\n"
	  "    let q: str = \"qqqq\"; q.cap = 5i32;\n"
	  "    let p: str = \"hi\";   p.cap = 8i32;\n"
	  "    let arr: [3]rec;\n"
	  "    let pr: *rec = &arr[1];\n"
	  "    pr.f = q;\n"
	  "    arr[1].f = p;\n"
	  "    let s: str = arr[1].f;\n"
	  "    if (s.cap: i32 != 8) { return 1; };\n"
	  "    if (s.len: i32 != 2) { return 2; };\n"
	  "    if (s[0] != 104u8) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
	/* B — `sl[i].f = v` into a []S local slice (MOVQ slice.ptr base,
	 * value element). The slice views the same backing array; poison the
	 * element through the array pointer, store the test str through the
	 * slice, read it back through the slice. */
	{ "arrfield_store_slice_value",
	  "type rec = struct { f: str };\n"
	  "export fn main() i32 = {\n"
	  "    let q: str = \"qqqq\"; q.cap = 5i32;\n"
	  "    let p: str = \"hi\";   p.cap = 8i32;\n"
	  "    let arr: [3]rec;\n"
	  "    let pr: *rec = &arr[1];\n"
	  "    pr.f = q;\n"
	  "    let sl: []rec = arr[0:3];\n"
	  "    sl[1].f = p;\n"
	  "    let s: str = sl[1].f;\n"
	  "    if (s.cap: i32 != 8) { return 1; };\n"
	  "    if (s.len: i32 != 2) { return 2; };\n"
	  "    if (s[0] != 104u8) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
	/* D — `arr[i].f = v` into a [N]*S pointer element (LEAQ base, MOVQ
	 * deref to the *S, then store at the field). The element points at a
	 * separately-built struct poisoned via the proven s1local field store
	 * (`st.f = q`); the G1 store derefs arr[1] and overwrites st.f. */
	{ "arrfield_store_ptr_elem",
	  "type rec = struct { f: str };\n"
	  "export fn main() i32 = {\n"
	  "    let q: str = \"qqqq\"; q.cap = 5i32;\n"
	  "    let p: str = \"hi\";   p.cap = 8i32;\n"
	  "    let st: rec;\n"
	  "    st.f = q;\n"
	  "    let arr: [3]*rec;\n"
	  "    arr[1] = &st;\n"
	  "    arr[1].f = p;\n"
	  "    let s: str = arr[1].f;\n"
	  "    if (s.cap: i32 != 8) { return 1; };\n"
	  "    if (s.len: i32 != 2) { return 2; };\n"
	  "    if (s[0] != 104u8) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[96], tmpdir[96], cmd[1024];
	snprintf(src, sizeof src, "/tmp/strarrfieldstore_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/strarrfieldstore_%d_d_%d", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s",
	    tmpdir, driver, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[160];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

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,
			    "str_arrfield_store_cap_run: 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,
				    "str_arrfield_store_cap_run[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	if (fail) {
		fprintf(stderr, "str_arrfield_store_cap_run: %d/%d fixtures failed\n",
		    fail, total);
		return 1;
	}
	printf("str_arrfield_store_cap_run: %d/%d ok\n", total, total);
	return 0;
}