ww/test/wcc/912_sar_shr_run.c

/*
 * 912_sar_shr_run — runtime + byte-id net for #136: signed right-shift
 * (both plain `>>` and `>>=`) must use SAR (arithmetic, sign-extends
 * MSB), not SHR (logical, zero-fill). Pre-fix BOTH stages emitted SHRQ
 * for signed RSHIFT because A_SARQ wasn't in the w6a opcode table, so
 * `let i: i32 = -200; i >>= 2;` produced i = 0x3FFFFFCE (1073741774)
 * instead of -50. cs==ww held → gate-blind. #133-expanded shipped with
 * this pre-existing concern documented (parity with cgen.c:4145 deref-
 * lvalue compound site); #136 closes it.
 *
 * Fix: add A_SARQ to w6a + w6c + w6a_ww opcode tables (encoding REX.W
 * D3 /7, parallel to SHR's D3 /5), then sweep cgen sites in both
 * stages to dispatch SARQ vs SHRQ on the operand signedness. Sites
 * covered (per-stage 6 each):
 *   - plain `>>` binop (cgbin TK_RSHIFT)
 *   - chained-ptr-field compound RSHIFTEQ (#133-expanded site 1)
 *   - N_INDEX-lhs compound RSHIFTEQ (#133-expanded site 2)
 *   - deref-target compound RSHIFTEQ (pre-existing)
 *   - top-level let compound RSHIFTEQ
 *   - IDENT-local compound RSHIFTEQ
 *
 * The bootstrap audit at design time showed zero current signed-RSHIFT
 * callers in lib/+selfhost/, so 990-997 byte-id stays GREEN; the only
 * shifts are on the previously-broken paths.
 *
 * Rows cover the operator + signedness × storage matrix:
 *   - i32_neg_rshifteq: lead's repro pattern, -200 >>= 2 = -50 (was
 *     1073741774 pre-fix on SHRQ)
 *   - i64_neg_rshifteq: same shape, i64
 *   - i32_pos_rshifteq: control, SARQ and SHRQ produce same result on
 *     positives; asserts no regression
 *   - u32_rshifteq: unsigned control, must still use SHRQ (no change)
 *   - i32_neg_rshift_binop: plain `>>` (not compound) on negative i32,
 *     covers the cgen 2596 / 3176 TK_RSHIFT N_BIN site
 *
 * Each row carries (a) cstage `ww build` + run asserting the exit
 * code and (b) w6c vs w6c_ww `.s` cmp (rule-10 byte-id). Exit codes
 * use small absolute values + 256 to encode signed expectations:
 * -50 → 206 = 256-50 (Unix exit is 8-bit unsigned). i64 row clamped
 * similarly.
 */
#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_exit; };

static const struct row rows[] = {
	/* The #136 repro: signed i32 >>=. Pre-fix produced wrong large
	 * positive; post-fix produces -50. Exit code = -50 as u8 = 206. */
	{ "i32_neg_rshifteq",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "	let i: i32 = -200;\n"
	  "	i >>= 2;\n"
	  "	return i;\n"
	  "};\n", 206 },
	/* signed i64 >>=. Same shape, wider type. Result -50 as exit u8
	 * = 206. */
	{ "i64_neg_rshifteq",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "	let i: i64 = -200i64;\n"
	  "	i >>= 2i64;\n"
	  "	return i: i32;\n"
	  "};\n", 206 },
	/* Positive control: SARQ and SHRQ agree. 200 >> 2 = 50. */
	{ "i32_pos_rshifteq",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "	let i: i32 = 200;\n"
	  "	i >>= 2;\n"
	  "	return i;\n"
	  "};\n", 50 },
	/* Unsigned control: SHRQ unchanged. 200u32 >> 2 = 50. */
	{ "u32_rshifteq",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "	let i: u32 = 200u32;\n"
	  "	i >>= 2u32;\n"
	  "	return i: i32;\n"
	  "};\n", 50 },
	/* Plain `>>` (not compound) on signed negative: covers cgbin
	 * TK_RSHIFT site (cgen.c:2596 / cgenexpr.ww:3176). */
	{ "i32_neg_rshift_binop",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "	let i: i32 = -200;\n"
	  "	let r: i32 = i >> 2;\n"
	  "	return r;\n"
	  "};\n", 206 },
	{ NULL, NULL, 0 }
};

static int
slurp_eq(const char *a, const char *b)
{
	FILE *fa = fopen(a, "rb");
	FILE *fb = fopen(b, "rb");
	if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
	int rc = 0;
	for (;;) {
		int ca = fgetc(fa);
		int cb = fgetc(fb);
		if (ca != cb) { rc = -1; break; }
		if (ca == EOF) break;
	}
	fclose(fa); fclose(fb);
	return rc;
}

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 w6c[1100], w6c_ww[1100];
	snprintf(w6c, sizeof w6c, "%s/w6c", bin);
	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);
	if (access(w6c_ww, X_OK) != 0) {
		fprintf(stderr, "sarshr: w6c_ww missing — cannot run the "
		    "cs==ww byte-id gate (the whole point of this test)\n");
		return 1;
	}

	int n = 0, fail = 0;
	for (int i = 0; rows[i].src; i++, n++) {
		char src[64];
		snprintf(src, sizeof src, "/tmp/wwsar_%d_%d.ww", getpid(), i);
		FILE *f = fopen(src, "wb");
		if (f == NULL) { fail++; continue; }
		fputs(rows[i].src, f);
		fclose(f);

		char tmpdir[64];
		snprintf(tmpdir, sizeof tmpdir, "/tmp/wwsar_%d_d_%d",
		    getpid(), i);
		mkdir(tmpdir, 0755);

		char cmd[2048];
		snprintf(cmd, sizeof cmd, "cd %s && %s/ww build %s",
		    tmpdir, bin, src);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "row[%s]: cstage build failed\n",
			    rows[i].label);
			fail++;
			unlink(src); rmdir(tmpdir);
			continue;
		}

		char outbin[128];
		const char *base = strrchr(src, '/');
		base = base ? base + 1 : src;
		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
		char *dot = strrchr(outbin, '.');
		if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';

		int got = runwait(outbin);
		if (got != rows[i].want_exit) {
			fprintf(stderr, "row[%s]: cstage exit %d, want %d\n",
			    rows[i].label, got, rows[i].want_exit);
			fail++;
		}
		unlink(outbin); rmdir(tmpdir);

		char cs_s[64], ws_s[64];
		snprintf(cs_s, sizeof cs_s, "/tmp/wwsar_%d_%d_cs.s",
		    getpid(), i);
		snprintf(ws_s, sizeof ws_s, "/tmp/wwsar_%d_%d_ww.s",
		    getpid(), i);

		snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
		    w6c, cs_s, src);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "row[%s]: w6c failed\n", rows[i].label);
			fail++; unlink(src); continue;
		}
		snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
		    w6c_ww, ws_s, src);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "row[%s]: w6c_ww failed\n",
			    rows[i].label);
			fail++; unlink(src); unlink(cs_s); continue;
		}
		if (slurp_eq(cs_s, ws_s) != 0) {
			fprintf(stderr,
			    "row[%s]: cstage/wwstage .s DIFFER (rule-10 "
			    "byte-id violation)\n", rows[i].label);
			fail++;
		}
		unlink(src); unlink(cs_s); unlink(ws_s);
	}

	if (fail) {
		fprintf(stderr, "%d/%d sar/shr tests failed\n", fail, n);
		return 1;
	}
	printf("sarshr: %d/%d ok (cstage run + cs==ww byte-id)\n",
	    n, n);
	return 0;
}