ww/test/wcc/640_int_cast_signed.c

/*
 * 640_int_cast_signed — signed narrow `(i64): i8|i16|i32` must
 * sign-extend the narrowed value, not silently truncate. Each
 * fixture casts a high-bit-set source to a narrow signed type,
 * widens back to i64, and returns 42 on the expected match. A
 * cast that fails to sign-extend leaks the low bits and the
 * comparison falls through to the `0` arm.
 *
 * Exercises both stages via the user-facing `ww run` (cstage)
 * and `ww_ww run` (wwstage) when present; the loop runs each
 * driver in turn so a regression on either side is caught
 * here without spawning extra targets.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "wwtestpkg.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[] = {
	/* i8 ← 0xFFFF_FF80: low byte is 0x80, expect -128 after
	 * narrow + widen-back round trip. */
	{ "i8_high_bits_set",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0xFFFFFF80i64;\n"
	  "  let y: i8 = x: i8;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -128i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i8 ← 0x80: bare low byte still encodes -128 once narrowed. */
	{ "i8_low_byte_negative",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0x80i64;\n"
	  "  let y: i8 = x: i8;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -128i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i8 ← 0x7F: positive, no sign-extend. */
	{ "i8_positive_max",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0x7Fi64;\n"
	  "  let y: i8 = x: i8;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == 127i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i16 ← 0xFFFF_8000: low 16 bits encode -32768. */
	{ "i16_high_bits_set",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0xFFFF8000i64;\n"
	  "  let y: i16 = x: i16;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -32768i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i16 ← 0x8000: low half-word's sign bit alone. */
	{ "i16_low_word_negative",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0x8000i64;\n"
	  "  let y: i16 = x: i16;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -32768i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i32 ← 0xFFFFFFFF_80000000: low 32 bits encode INT32_MIN. */
	{ "i32_high_bits_set",
	  "fn main() i32 = {\n"
	  "  let x: i64 = -2147483648i64;\n"
	  "  let y: i32 = x: i32;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -2147483648i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* i32 ← 0x0000_0000_8000_0000: low dword's sign bit alone. */
	{ "i32_low_dword_negative",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0x80000000i64;\n"
	  "  let y: i32 = x: i32;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -2147483648i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* Compare against the narrow target's own range, not the
	 * widened slot — i32 - 1 must roll over to INT32_MAX after
	 * MOVSXD sign-extends the wrap-around value. */
	{ "i32_wrap_negative_to_positive",
	  "fn main() i32 = {\n"
	  "  let x: i64 = 0x80000000i64;\n"
	  "  let y: i32 = (x - 1i64): i32;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == 2147483647i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* `!T` error-flag wrapper must not block the narrow clamp.
	 * Pins the wwstage N_TBANG peel in cgcast: without it, the
	 * unsigned u8 mask was skipped and 0x1FF leaked through. */
	{ "u8bang_unsigned_narrow",
	  "type u8x = !u8;\n"
	  "fn main() i32 = {\n"
	  "  let y: u8x = 0x1FFu64: u8x;\n"
	  "  let z: u64 = y: u64;\n"
	  "  if (z == 0xFFu64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
	/* Signed `!T` companion — sign-extend must fire through the
	 * bang wrapper so `(0xFF80): !i8 → i64` reads back -128. */
	{ "i8bang_signed_narrow",
	  "type i8x = !i8;\n"
	  "fn main() i32 = {\n"
	  "  let y: i8x = 0xFF80i64: i8x;\n"
	  "  let z: i64 = y: i64;\n"
	  "  if (z == -128i64) { return 42; };\n"
	  "  return 0;\n"
	  "};\n",
	  42 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char tmpdir[64], src[128], outbin[128], rmcmd[160], cmd[1024];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/wwic_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(src, sizeof src, "%s/wwic_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/wwic_%d_%d", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);

	FILE *f = fopen(src, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	wwtest_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[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];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[1024];
	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, "int_cast_signed: 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,
				    "int_cast_signed[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}
	if (fail) {
		fprintf(stderr,
		    "int_cast_signed: %d/%d fixtures failed\n", fail, total);
		return 1;
	}
	printf("int_cast_signed: %d/%d ok\n", total, total);
	return 0;
}