ww/test/wcc/680_arr_elem_field.c

/*
 * 680_arr_elem_field — `arr[i].field` lowers to a single (idx*esz +
 * base) → field-load sequence, not a fall-through that returns the
 * element value (or address) as the dot's result. Filed from task #8
 * (originally framed as a wwstage bug; investigation flipped — cstage's
 * N_DOT had no N_INDEX-lhs branch and fell through, leaving the
 * caller's (AX, BX) shape junk for str/scalar leaf consumers).
 *
 * The cgenutil dotchainresolve workaround spills via `let nd = stk[i];
 * nd.str` to keep cstage from seeing the direct shape; this test pins
 * the direct shape so the spill can be retired in a follow-up.
 *
 * Coverage — both `[N]*Struct` and `[N]Struct` shapes, str / i32 / u8
 * fields. Cstage and wwstage each on every fixture; wwstage gated on
 * access(X_OK).
 *
 * `&arr[i].field` (TK_AMP through chained N_DOT N_INDEX) is task #9
 * territory and intentionally out of scope here. Write-side
 * `arr[i].field = v` is covered elsewhere — the wwstage write gap
 * surfaces separately.
 */
#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[] = {
	/* [N]*Struct, str field at non-zero offset. The original
	 * task-#8 repro — stk[0].name where stk: [16]*nd.
	 * Returns len("hello") = 5. */
	{ "ptr_arr_str_field",
	  "type nd = struct {\n"
	  "    a: i32, b: i32,\n"
	  "    name: str,\n"
	  "};\n"
	  "fn main() i32 = {\n"
	  "    let v: nd; v.a = 1; v.b = 2; v.name = \"hello\";\n"
	  "    let stk: [16]*nd; stk[0] = &v;\n"
	  "    let s: str = stk[0].name;\n"
	  "    return s.len: i32;\n"
	  "};\n",
	  5 },
	/* [N]*Struct, scalar i32 field. Pins the non-str leaf load
	 * path through fldloadop (MOVSXD here for i32). Returns 42. */
	{ "ptr_arr_i32_field",
	  "type nd = struct { name: str, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let v: nd; v.name = \"hi\"; v.x = 42;\n"
	  "    let stk: [16]*nd; stk[0] = &v;\n"
	  "    return stk[0].x;\n"
	  "};\n",
	  42 },
	/* [N]*Struct, u8 field — pins the sub-word zero-extend (MOVZBQ)
	 * branch. Returns 7. */
	{ "ptr_arr_u8_field",
	  "type nd = struct { tag: u8, pad: u8, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let v: nd; v.tag = 7u8; v.pad = 0u8; v.x = 99;\n"
	  "    let stk: [8]*nd; stk[0] = &v;\n"
	  "    return stk[0].tag: i32;\n"
	  "};\n",
	  7 },
	/* [N]Struct (value array), str field. Element address goes
	 * straight into AX; field load reads at foff(AX). Returns
	 * len("world") = 5. */
	{ "val_arr_str_field",
	  "type nd = struct { name: str, x: i32 };\n"
	  "fn setit(p: *nd, s: str, vv: i32) void = { p.name = s; p.x = vv; };\n"
	  "fn main() i32 = {\n"
	  "    let arr: [4]nd;\n"
	  "    setit(&arr[1], \"world\", 100);\n"
	  "    let s: str = arr[1].name;\n"
	  "    return s.len: i32;\n"
	  "};\n",
	  5 },
	/* [N]Struct, scalar i32 field. Pins the value-array path for a
	 * non-str leaf — same address compute, MOVL load. Returns 100. */
	{ "val_arr_i32_field",
	  "type nd = struct { name: str, x: i32 };\n"
	  "fn setit(p: *nd, s: str, vv: i32) void = { p.name = s; p.x = vv; };\n"
	  "fn main() i32 = {\n"
	  "    let arr: [4]nd;\n"
	  "    setit(&arr[2], \"q\", 100);\n"
	  "    return arr[2].x;\n"
	  "};\n",
	  100 },
	/* [N]Struct, u8 leaf — pins the value-array sub-word path
	 * (no MOVQ-to-deref, direct address arithmetic into AX) then
	 * fldloadop's MOVZBQ. Returns 9. */
	{ "val_arr_u8_field",
	  "type nd = struct { tag: u8, pad: u8, x: i32 };\n"
	  "fn setit(p: *nd, t: u8, vv: i32) void = { p.tag = t; p.x = vv; };\n"
	  "fn main() i32 = {\n"
	  "    let arr: [4]nd;\n"
	  "    setit(&arr[2], 9u8, 50);\n"
	  "    return arr[2].tag: i32;\n"
	  "};\n",
	  9 },
	/* [N]*Struct, i8 leaf with a negative value — pins that
	 * fldloadop sign-extends (MOVBQSX) through the new branch
	 * rather than the old MOVZBQ. Compare against -3 in i32 to
	 * avoid the WEXITSTATUS truncation collision (sign-ext: -3,
	 * zero-ext: 253 — both clash mod 256 if returned directly). */
	{ "ptr_arr_i8_signed",
	  "type nd = struct { tag: i8, pad: u8, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let v: nd; v.tag = -3i8; v.pad = 0u8; v.x = 0;\n"
	  "    let stk: [4]*nd; stk[0] = &v;\n"
	  "    let t: i32 = stk[0].tag: i32;\n"
	  "    if (t == -3) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* Idx is a non-zero variable expression — pins the IMULQ path
	 * and confirms the address compute doesn't accidentally fold
	 * to a constant displacement. Returns len("third") = 5. */
	{ "ptr_arr_dyn_idx",
	  "type nd = struct { name: str, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let a: nd; a.name = \"first\"; a.x = 1;\n"
	  "    let b: nd; b.name = \"two\";   b.x = 2;\n"
	  "    let c: nd; c.name = \"third\"; c.x = 3;\n"
	  "    let stk: [4]*nd;\n"
	  "    stk[0] = &a; stk[1] = &b; stk[2] = &c;\n"
	  "    let i: i32 = 2;\n"
	  "    let s: str = stk[i].name;\n"
	  "    return s.len: i32;\n"
	  "};\n",
	  5 },
};

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/wae_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(src, sizeof src, "%s/wae_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/wae_%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[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_elem_field: 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_elem_field[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}
	if (fail) {
		fprintf(stderr,
		    "arr_elem_field: %d/%d fixtures failed\n", fail, total);
		return 1;
	}
	printf("arr_elem_field: %d/%d ok\n", total, total);
	return 0;
}