ww/test/wcc/682_arr_enum_elem.c

/*
 * 682_arr_enum_elem — cstage and wwstage agree, byte-for-byte and at
 * runtime, on `[N]enum` element access (task #8).
 *
 * The bug: wwstage's elemsizeofc (selfhost/cmd/wcc/cgenutil.ww) was the
 * odd-one-out among the elem*c helpers — its siblings elemissignedc /
 * elemisfloatc read the checker-stamped tinfo (t.type_.sub), but
 * elemsizeofc derived the element width purely structurally
 * (elemsizeof -> primsize -> slotsize). A named-narrow element
 * (`[N]tk`, tk = enum i32) is not a builtin prim, so primsize returned
 * 0 and elemsizeofc fell through to a raw 8-byte slot instead of the
 * enum's i32 backing (4). That mis-sized BOTH manifestations through
 * the one choke-point:
 *   (a) cgindex READ  — `a[i]` strode by 8 (MOVQ) where cstage strode by
 *       4 (MOVSXD), reading the wrong/out-of-bounds element for i>=1.
 *   (b) array-init STORE — a local `[N]enum` literal init stored at
 *       stride 8 into a stride-4 frame slot, overrunning the slot and
 *       smashing the frame -> wwstage-built binary SEGFAULTED.
 * cstage is runtime-correct (cgen.c N_INDEX idx_eff(bt)->sub->size,
 * N_LET array-init lu->sub->size, cgen.c:6387). The fix aligns wwstage
 * UP: elemsizeofc now reads the element size off the stamped tinfo
 * (peeling TY_NAMED), recovering 4 for `enum i32` and bringing all four
 * elem*c helpers onto the same tinfo SSoT.
 *
 * No in-tree `[N]enum` / aliased-narrow element existed before kwtab,
 * which is why this was byte-id-gate-blind until now.
 *
 *   row              | shape                              | want
 *   -----------------+------------------------------------+--------------
 *   global_idx0      | global [4]tk, return g[0]. idx0 is | 7  + byte-id
 *                    | stride-independent (offset 0).     |
 *   global_read      | global [4]tk, return g[2]. Pre-fix | 99 + byte-id
 *                    | stride-8 read offset 16 = past the |
 *                    | 16-byte array -> garbage.          |
 *   local_read       | LOCAL [4]tk init, return a[1].     | 21 + byte-id
 *                    | Exercises the array-init STORE +   |
 *                    | the stride-4 READ together.        |
 *   local_init_sum   | LOCAL [4]tk, return a[0]+a[3].     | 10 + byte-id
 *                    | First+last element after init.     |
 *   local_signed     | LOCAL [2]tk with a negative enum   | 251 (-5)
 *                    | value, return a[0]:i32. Pins the   | + byte-id
 *                    | MOVSXD sign-extend at stride 4     |
 *                    | (pre-fix MOVQ read 8 bytes).       |
 *   frame_smash      | LOCAL [6]tk init + read a[5].      | 5  + byte-id
 *                    | Pre-fix stride-8 store writes 48   |
 *                    | bytes into a 24-byte slot ->       |
 *                    | frame smash / SEGFAULT under       |
 *                    | wwstage. Correct stride-4 store    |
 *                    | (24 bytes) round-trips a[5]=5.     |
 *   width1_u8        | LOCAL [3]tu (enum u8), read a[1].  | 200 + byte-id
 *                    | Pins the narrow-scalar class at    |
 *                    | width 1: stride-1 store + MOVZBQ   |
 *                    | zero-extend load (UNSIGNED enum).  |
 *                    | Pre-fix stride-8 store/read over-  |
 *                    | runs the 3-byte slot -> garbage.   |
 *   width2_i16       | LOCAL [3]ts (enum i16) w/ negative | 251 (-5)
 *                    | value, read a[1]:i32. Pins width 2:| + byte-id
 *                    | stride-2 store + MOVSWQ sign-      |
 *                    | extend (pre-fix stride-8 garbage). |
 *
 * width1/width2 widen the coverage from the single enum-i32 (width 4)
 * case to the whole {1,2,4} narrow-scalar class the fix closes, and add
 * the unsigned (MOVZBQ) load path alongside the signed (MOVSXD/MOVSWQ).
 *
 * Exit-code rows confirm both stages run correctly. The asm-byte-id
 * rows pin the symmetric stride-4 MOVSXD emit (cstage == wwstage);
 * pre-fix wwstage emitted stride-8 MOVQ, so the diff was non-empty.
 */
#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[] = {
	{ "global_idx0",
	  "type tk = enum i32 { A = 7i32, B = 21i32, C = 99i32, D = 3i32 };\n"
	  "let g: [4]tk = [tk.A, tk.B, tk.C, tk.D];\n"
	  "fn main() i32 = {\n"
	  "\treturn g[0]: i32;\n"
	  "};\n",
	  7 },

	{ "global_read",
	  "type tk = enum i32 { A = 7i32, B = 21i32, C = 99i32, D = 3i32 };\n"
	  "let g: [4]tk = [tk.A, tk.B, tk.C, tk.D];\n"
	  "fn main() i32 = {\n"
	  "\treturn g[2]: i32;\n"
	  "};\n",
	  99 },

	{ "local_read",
	  "type tk = enum i32 { A = 7i32, B = 21i32, C = 99i32, D = 3i32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [4]tk = [tk.A, tk.B, tk.C, tk.D];\n"
	  "\treturn a[1]: i32;\n"
	  "};\n",
	  21 },

	{ "local_init_sum",
	  "type tk = enum i32 { A = 7i32, B = 21i32, C = 99i32, D = 3i32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [4]tk = [tk.A, tk.B, tk.C, tk.D];\n"
	  "\treturn (a[0]: i32) + (a[3]: i32);\n"
	  "};\n",
	  10 },

	{ "local_signed",
	  "type tk = enum i32 { A = 7i32, G = -5i32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [2]tk = [tk.G, tk.A];\n"
	  "\treturn a[0]: i32;\n"
	  "};\n",
	  251 },

	{ "frame_smash",
	  "type tk = enum i32 { A = 7i32, B = 21i32, C = 99i32,\n"
	  "\tD = 3i32, E = 11i32, F = 5i32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [6]tk = [tk.A, tk.B, tk.C, tk.D, tk.E, tk.F];\n"
	  "\treturn a[5]: i32;\n"
	  "};\n",
	  5 },

	{ "width1_u8",
	  "type tu = enum u8 { A = 7u8, B = 200u8, C = 3u8 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [3]tu = [tu.A, tu.B, tu.C];\n"
	  "\treturn a[1]: i32;\n"
	  "};\n",
	  200 },

	{ "width2_i16",
	  "type ts = enum i16 { A = 7i16, G = -5i16, C = 99i16 };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: [3]ts = [ts.A, ts.G, ts.C];\n"
	  "\treturn a[1]: i32;\n"
	  "};\n",
	  251 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/aee_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/aee_%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 2>/dev/null",
	    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[128];
	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;
}

/* asm_byte_identical — generate .s via cstage's w6c and wwstage's
 * w6c_ww and diff. This is the regression-pinning row for #8: pre-fix
 * wwstage emitted stride-8 MOVQ where cstage emitted stride-4 MOVSXD,
 * so the diff was non-empty. */
static int
asm_byte_identical(const char *bin, const struct row *r, int i)
{
	char src[64], cs[64], ws[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/aee_asm_%d_%d.ww", getpid(), i);
	snprintf(cs,  sizeof cs,  "/tmp/aee_asm_%d_%d_c.s", getpid(), i);
	snprintf(ws,  sizeof ws,  "/tmp/aee_asm_%d_%d_w.s", getpid(), i);

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

	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s 2>/dev/null", bin, cs, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c errored\n", r->label);
		unlink(src);
		return -1;
	}
	snprintf(cmd, sizeof cmd, "%s/w6c_ww -o %s %s 2>/dev/null",
	    bin, ws, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label);
		unlink(src); unlink(cs);
		return -1;
	}

	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	int rc = 0;
	if (!fc || !fw) {
		rc = -1;
	} else {
		for (;;) {
			int a = fgetc(fc);
			int b = fgetc(fw);
			if (a != b) { rc = -1; break; }
			if (a == EOF) break;
		}
	}
	if (fc) fclose(fc);
	if (fw) fclose(fw);
	if (rc != 0)
		fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n",
		    r->label);
	unlink(src); unlink(cs); unlink(ws);
	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 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, "arr_enum_elem: 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,
				    "arr_enum_elem[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	if (access(wdrv, X_OK) == 0) {
		for (int i = 0; i < n; i++) {
			total++;
			if (asm_byte_identical(bin, &rows[i], i) != 0)
				fail++;
		}
	}

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