ww/test/wcc/710_cast_enum_movl.c

/*
 * 710_cast_enum_movl — cstage and wwstage agree byte-for-byte on the
 * N_CAST narrow-clamp when the dst is an enum (task #25).
 *
 * Pre-fix: cstage's N_CAST handler in cmd/w6c/cgen.c walked
 * `type_isint`/`type_isunsigned` which recurse through TY_ENUM into
 * `t->sub`; for a u32→enum-u32 cast that landed on the size==4 unsigned
 * branch and emitted a redundant `MOVL AX, AX`. Wwstage's cgcast walker
 * (selfhost/cmd/wcc/cgenexpr.ww) only steps through N_TBANG / N_TNAME;
 * `aliaslookup` on an enum returns the N_TENUM body, which breaks the
 * loop and skips the clamp.
 *
 * Surfaced by worker-stat during #10: when kstat.mode was first typed
 * as raw `u32`, `out.mode = k.mode` parsed as a u32→enum-u32 cast via
 * `fs.mode`, and the cstage→wwstage asm divergence broke 993_ww_ww +
 * 995_self_rebuild on the first selfhost pass. Workaround in tree
 * (lib/os/os.ww:498, kstat.mode: mode) sidesteps until this fix lands;
 * reverting it is a sibling cleanup, out of scope here.
 *
 * Fix shape: cstage's N_CAST clamp gate adds an explicit
 * `tu->kind == TY_ENUM` skip, mirroring wwstage's lacuna. The predicate
 * recursion through TY_ENUM in `type_isint`/`type_isunsigned` is
 * preserved — other call sites depend on it; only this site gates
 * explicitly. Skip is on dst kind only, so `enum-u32 → u32` still emits
 * the clamp, matching wwstage's asymmetry. A principled
 * identity-width identity-sign skip across both stages is filed as
 * a separate followup.
 *
 *   row              | shape                                  | gate
 *   -----------------+----------------------------------------+----------
 *   u32_to_enum_u32  | `let y: m = x: m;` with m=enum u32.    | exit=7
 *                    | Headline. Both stages emit ONE MOVL    | + byte-id
 *                    | (the slot load); no clamp.             |
 *   enum_u32_to_u32  | reverse direction: `let z: u32 = y;`.  | exit=7
 *                    | Both stages emit clamp MOVL AX, AX     | + byte-id
 *                    | (post-load) — pins the asymmetry.      |
 *   u32_to_enum_u8   | dst is enum u8. Pre-fix cstage emits   | exit=7
 *                    | ANDQ $0xFF; wwstage skips. Post-fix    | + byte-id
 *                    | both skip — matches wwstage. (Width    |
 *                    | narrowing through the enum-u8 is a     |
 *                    | known shared gap; principled followup. |
 *                    | The u8-typed local's slot load uses    |
 *                    | MOVZBQ which masks anyway, so program  |
 *                    | semantics stays right at this width.)  |
 *   i64_to_enum_i32  | signed-narrow: dst is enum i32.        | exit=7
 *                    | Pre-fix cstage emits MOVSXD; post-fix  | + byte-id
 *                    | skips. The slot is read with MOVSXD    |
 *                    | downstream so sign-ext survives.       |
 *   struct_field_rt  | mirror of lib/os fillfilestat: a u32   | exit=7
 *                    | struct field copied into an enum-typed | + byte-id
 *                    | field by chained N_DOT. Pins the field-|
 *                    | store path through the cast.           |
 *
 * Cstage exit-code rows confirm the binary still runs correctly
 * post-fix; the asm-byte-id rows are the regression-pinning rows for
 * the symmetric-emit contract. ww2!=ww3 byte-id (995_self_rebuild)
 * covers a broader surface but doesn't isolate this corner.
 */
#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[] = {
	/* 1. Headline #25 case: u32 → enum-u32. Pre-fix cstage emitted
	 * `MOVL AX, AX` after the slot load; wwstage skipped. The cast
	 * is a no-op at runtime so program semantics is unchanged
	 * either way — exit code stays 7 regardless. The asm-byte-id
	 * row is what catches the regression. */
	{ "u32_to_enum_u32",
	  "type mymode = enum u32 { A = 1u32, B = 2u32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet x: u32 = 7u32;\n"
	  "\tlet y: mymode = x: mymode;\n"
	  "\treturn (y: u32): i32;\n"
	  "};\n",
	  7 },

	/* 2. Reverse direction: enum-u32 → u32. Both stages still emit
	 * the clamp `MOVL AX, AX` here (wwstage's walker steps through
	 * the N_TNAME("u32") rhs and primsize=4 fires). The byte-id
	 * row pins that the fix didn't accidentally widen the skip to
	 * include this case. */
	{ "enum_u32_to_u32",
	  "type mymode = enum u32 { A = 1u32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet y: mymode = 7u32: mymode;\n"
	  "\tlet z: u32 = y: u32;\n"
	  "\treturn z: i32;\n"
	  "};\n",
	  7 },

	/* 3. Different enum width: u32 → enum-u8. Wwstage skips clamp
	 * because dst is an enum (lacuna); cstage now also skips
	 * (mirror). The local's u8 slot reads with MOVZBQ later, so
	 * the value 7 still reads back as 7. Pinning byte-id here
	 * documents that the skip is by dst-kind, not by dst-size —
	 * the principled identity-width fix would behave differently
	 * here, so this row is the canary that flips when the
	 * followup lands. */
	{ "u32_to_enum_u8",
	  "type small = enum u8 { A = 1u8 };\n"
	  "fn main() i32 = {\n"
	  "\tlet x: u32 = 7u32;\n"
	  "\tlet y: small = x: small;\n"
	  "\treturn (y: u32): i32;\n"
	  "};\n",
	  7 },

	/* 4. Signed-narrow path: i64 → enum-i32. Pre-fix cstage emitted
	 * `MOVSXD AX, AX`; wwstage skipped. Post-fix both skip. The
	 * enum-i32 local's slot read uses MOVSXD downstream so the
	 * sign-extension is recovered on use. */
	{ "i64_to_enum_i32",
	  "type sflag = enum i32 { A = 1i32 };\n"
	  "fn main() i32 = {\n"
	  "\tlet x: i64 = 7i64;\n"
	  "\tlet y: sflag = x: sflag;\n"
	  "\treturn (y: i32);\n"
	  "};\n",
	  7 },

	/* 5. Mirror of lib/os fillfilestat: struct field of one type
	 * copied into an enum-typed field of another struct via
	 * chained N_DOT. The `out.mode = k.mode` shape is exactly
	 * what blew up worker-stat's first kstat.mode: u32 attempt
	 * pre-fix (993_ww_ww + 995_self_rebuild went red). */
	{ "struct_field_rt",
	  "type mymode = enum u32 { A = 1u32 };\n"
	  "type src = struct { mode: u32 };\n"
	  "type dst = struct { mode: mymode };\n"
	  "fn main() i32 = {\n"
	  "\tlet a: src = src { mode = 7u32 };\n"
	  "\tlet b: dst;\n"
	  "\tb.mode = a.mode: mymode;\n"
	  "\treturn (b.mode: u32): i32;\n"
	  "};\n",
	  7 },
};

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/cem_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/cem_%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 #25; an
 * exit-code-only comparison wouldn't catch a redundant MOVL drift
 * because the program semantics is unchanged. */
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/cem_asm_%d_%d.ww", getpid(), i);
	snprintf(cs,  sizeof cs,  "/tmp/cem_asm_%d_%d_c.s", getpid(), i);
	snprintf(ws,  sizeof ws,  "/tmp/cem_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, "cast_enum_movl: 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,
				    "cast_enum_movl[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	/* Asm byte-identity diff, only when wwstage is built. This is
	 * the row that pins the #25 fix. */
	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,
		    "cast_enum_movl: %d/%d fixtures failed\n", fail, total);
		return 1;
	}
	printf("cast_enum_movl: %d/%d ok\n", total, total);
	return 0;
}