test: port 989_ffivariadic_run to ww; retire the C carrier

test/tool/ffivariadic_test.ww

@@ -0,0 +1,127 @@
+package ffivariadic_test;
+
+// SysV variadic-FFI AL contract, runtime-gated on both driver stages.
+// Port of the retired native carrier test/wcc/989_ffivariadic_run.c;
+// every assertion preserved.
+//
+// A ww caller of a C variadic fn (`@symbol("fixture") fn fixture(n:
+// i64, ...) f64;`) must set AL to the count of XMM regs used for the
+// variadic FLOAT args: the C callee gates its xmm-save-area stores on
+// `test %al,%al`, so a wrong AL makes va_arg(double) read garbage.
+// The pre-fix bug hardcoded AL=0 (`XORQ AX,AX`) — correct only for a
+// zero-float call. Ref SysV §3.5.7, ref/qbe/amd64/sysv.c:384.
+//
+// Byte-id can never see AL correctness, so each row builds a ww
+// caller against the host-cc-built va_arg(double) summer
+// (test/wcc/data/ffivariadic/fixture.c archived as
+// out/ffivariadic/libffifix.a, self-contained: zero relocs/undef
+// syms, no libc, so w6l links it hermetically) and asserts the
+// runtime sum via the binary's exit code, on BOTH `ww` and `ww_ww`.
+//
+// NON-VACUITY: fixture(2,1.0,2.0) is vacuous on this box — with AL=0
+// the two skipped xmm slots alias stale stack already holding
+// 1.0/2.0. At >=3 floats the coincidence breaks deterministically,
+// so every f64 row uses >=3 floats and reverting the fix FAILS here.
+//
+// f32 rows (#14): C default argument promotion widens each f32 arg
+// to f64. f32three — exact values, unpromoted MOVSS leaves stale
+// high 4B, sum misses 7.0. f32inexact — 0.1 is INEXACT in f32; the
+// expected side `(x: f64)` is the SAME var widened at runtime, so
+// equality holds iff the f32-ROUNDED value was promoted (not the f64
+// literal, not garbage); single f32 arg also lands the fi==1
+// boundary. f32mixed — only the f32 args promote; the native-f64 arg
+// passes at width, never double-promoted.
+//
+// Dropped C machinery, not assertions: the ww_ww-absent skip gate
+// (the Make target declares both drivers) and the unlink/rmdir
+// accounting (testenv.clean asserts the removal).
+
+import os;
+import os.exec;
+import strings;
+import testenv;
+import time;
+
+fn fail(label: str, why: str) void = {
+	let m: str = strings.concat("ffivariadic FAIL: ", label, " -- ",
+		why, "\n");
+	os.write(2, m.ptr, m.len: u64);
+	assert(false);
+};
+
+fn tmo() time.duration = {
+	return (240i64 * (time.second: i64)): time.duration;
+};
+
+// -1 encodes an abnormal (non-EXIT) termination, never a valid code.
+fn runcode(dir: str, name: str, argv: []str) i32 = {
+	let co: testenv.commandout;
+	testenv.runcommand(dir, dir, name, argv, tmo(), &co);
+	if (co.termination != exec.termination.EXIT) { return -1; };
+	return co.code;
+};
+
+fn caller(call: str, want: str) str = {
+	return strings.concat(
+		"package main;\n",
+		"@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n",
+		"export fn main() int = {\n",
+		"\tlet r: f64 = ", call, ";\n",
+		"\tif (r == ", want, ") { return 0; };\n",
+		"\treturn 1;\n",
+		"};\n");
+};
+
+@test fn variadic_al() void = {
+	let labels: []str = ["three", "five", "eight", "f32three",
+		"f32inexact", "f32mixed"];
+	let srcs: []str = [
+		caller("fixture(3, 1.0, 2.0, 3.0)", "6.0"),
+		caller("fixture(5, 1.0, 2.0, 3.0, 4.0, 5.0)", "15.0"),
+		caller("fixture(8, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0)",
+			"36.0"),
+		caller("fixture(3, 1.5: f32, 2.5: f32, 3.0: f32)", "7.0"),
+		strings.concat(
+			"package main;\n",
+			"@symbol(\"fixture\") fn fixture(n: i64, ...) f64;\n",
+			"export fn main() int = {\n",
+			"\tlet x: f32 = 0.1: f32;\n",
+			"\tlet r: f64 = fixture(1, x);\n",
+			"\tif (r == (x: f64)) { return 0; };\n",
+			"\treturn 1;\n",
+			"};\n"),
+		caller("fixture(3, 1.5: f32, 2.0, 3.5: f32)", "7.0"),
+	];
+	let libdir: str = strings.concat(testenv.repo(), "/out/ffivariadic");
+	let drvs: []str = ["ww", "ww_ww"];
+	let td: str = testenv.fresh();
+	let i: i32 = 0;
+	for (i < labels.len) {
+		let src: str = strings.concat(td, "/", labels[i], ".ww");
+		testenv.writefile(src, srcs[i]);
+		let s: i32 = 0;
+		for (s < 2) {
+			// "out." prefix: a bare <label>.<drv> stem collides with
+			// the <label>.ww SOURCE name on the cstage driver leg
+			let out: str = strings.concat(td, "/out.", labels[i], ".",
+				drvs[s]);
+			let av: []str = [testenv.driver(drvs[s]), "build",
+				strings.concat("-L", libdir), "-lffifix", "-o", out,
+				src];
+			if (runcode(td, strings.concat("build_", labels[i], "_",
+				drvs[s]), av) != 0) {
+				fail(labels[i], strings.concat(drvs[s],
+					" build failed (-lffifix link)"));
+			};
+			let rav: []str = [out];
+			if (runcode(td, strings.concat("run_", labels[i], "_",
+				drvs[s]), rav) != 0) {
+				fail(labels[i], strings.concat(drvs[s],
+					" wrong variadic sum (AL/promotion contract)"));
+			};
+			s += 1;
+		};
+		i += 1;
+	};
+	testenv.clean(td);
+};