ww/test/wcc/940_str_forrange_loopvar_run.c

/*
 * 940_str_forrange_loopvar_run — corpus coverage for the step-3 Fold 1
 * fold: ranging a `str` value-form (`for (let b .. s)`) and reading the
 * loop var `b` back must narrow to MOVZBQ (u8 zero-extend), matching
 * cstage. Pre-fold the wwstage cgen registered the loop var with a nil
 * tnode (str had no element node the way []u8 does), so the read-back
 * fell through localloadop to a wide MOVQ; cstage's checker stamps the
 * binding u8, so it narrowed. The fold synthesises the u8 element off
 * str.sub (Phase 2 F1) so the loop var carries a u8 tnode and the
 * existing narrow-load logic fires on its own.
 *
 * REAL GATE IS SHAPE BYTE-ID, NOT RUNTIME. The MOVQ-vs-MOVZBQ
 * divergence is runtime-benign: the slot is always written by a
 * MOVZBQ-into-AX then MOVQ-AX-into-slot, so the upper bytes are already
 * zero — a MOVQ read-back yields the same value a MOVZBQ would. A
 * runtime probe therefore passes on BOTH the buggy and the fixed code
 * and CANNOT distinguish them. The load-bearing gate is diffing the
 * cstage (w6c) and wwstage (w6c_ww) .s at the loop-var read:
 *   pre-fold:  cstage MOVZBQ  vs  wwstage MOVQ   (1-line diff)
 *   post-fold: byte-identical
 * This fixture exists for corpus presence — it confirms the path lowers
 * and runs correctly through both drivers; it does not by itself prove
 * the narrow.
 *
 * Loop-var read-back is exercised two ways the fold touches:
 *   - Site A: pass `b` to a fn (`use1(b)` → cgident read into an arg).
 *   - Site B: use `b` in an arithmetic expression (`sum += b: i32`).
 */
#include <stdio.h>
#include <stdlib.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[] = {
	/* Site A — read-back into a fn arg. "AB" is 0x41,0x42; the callee
	 * checks each byte zero-extends to its exact value, so a botched
	 * wide read (had the slot held garbage) would mismatch. */
	{ "sitea_arg_readback",
	  "fn check(x: u8) i32 = {\n"
	  "    if (x: i32 < 65) { return 1; };\n"
	  "    if (x: i32 > 66) { return 1; };\n"
	  "    return 0;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let s: str = \"AB\";\n"
	  "    for (let b .. s) {\n"
	  "        if (check(b) != 0) { return 1; };\n"
	  "    };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
	/* Site B — read-back in an arithmetic expression. Sum the bytes of
	 * "AB" (0x41 + 0x42 = 131) and confirm. */
	{ "siteb_expr_readback",
	  "export fn main() i32 = {\n"
	  "    let s: str = \"AB\";\n"
	  "    let sum: i32 = 0;\n"
	  "    for (let b .. s) {\n"
	  "        sum += b: i32;\n"
	  "    };\n"
	  "    if (sum != 131) { return 1; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char tmpdir[96], src[160], outbin[160], rmcmd[160], cmd[1024];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/strforrange_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(src, sizeof src, "%s/strforrange_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/strforrange_%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;
}

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

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