li := len(nargs) - 1
	last := nargs[li]
	nargs[li] = "-O0"
	nargs = append(nargs, extraArgs...)
	nargs = append(nargs, last)

	if *debugGcc {
		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(nargs, " "))
		os.Stderr.Write(stdin)
		fmt.Fprint(os.Stderr, "EOF\n")
	}
	stdout, stderr, _ := run(stdin, nargs)
	if *debugGcc {
		os.Stderr.Write(stdout)
		os.Stderr.Write(stderr)

	SHA256MSG2 (BX), X11     // 440f38cd1b
	SHA256MSG2 (R11), X11    // 450f38cd1b
	SHA256MSG2 X2, X11       // 440f38cdda
	SHA256MSG2 X11, X11      // 450f38cddb
	// Test VPERMQ with both uint8 and int8 immediate args
	VPERMQ $-40, Y8, Y8 // c443fd00c0d8
	VPERMQ $216, Y8, Y8 // c443fd00c0d8
	// Test that VPERMPD that shares ytab list with VPERMQ continues to work too.
	VPERMPD $-40, Y7, Y7 // c4e3fd01ffd8