M3:   "%mm3",
	M4:   "%mm4",
	M5:   "%mm5",
	M6:   "%mm6",
	M7:   "%mm7",
	X0:   "%xmm0",
	X1:   "%xmm1",
	X2:   "%xmm2",
	X3:   "%xmm3",
	X4:   "%xmm4",
	X5:   "%xmm5",
	X6:   "%xmm6",
	X7:   "%xmm7",
	X8:   "%xmm8",
	X9:   "%xmm9",
	X10:  "%xmm10",
	X11:  "%xmm11",
	X12:  "%xmm12",
	X13:  "%xmm13",
	X14:  "%xmm14",
	X15:  "%xmm15",
	CS:   "%cs",
	SS:   "%ss",

	xArgXmm          // arg xmm
	xArgXMM0         // arg <XMM0>
	xArgXmm1         // arg xmm1
	xArgXmm2         // arg xmm2
	xArgXmm2M128     // arg xmm2/m128
	xArgYmm2M256     // arg ymm2/m256
	xArgXmm2M16      // arg xmm2/m16
	xArgXmm2M32      // arg xmm2/m32
	xArgXmm2M64      // arg xmm2/m64
	xArgXmmM128      // arg xmm/m128
	xArgXmmM32       // arg xmm/m32
	xArgXmmM64       // arg xmm/m64

	// 387 floating point registers.
	F0
	F1
	F2
	F3
	F4
	F5
	F6
	F7

	// MMX registers.
	M0
	M1
	M2
	M3
	M4
	M5
	M6
	M7

	// XMM registers.
	X0
	X1
	X2
	X3
	X4
	X5
	X6
	X7
	X8
	X9
	X10
	X11
	X12
	X13
	X14
	X15

	// Segment registers.
	ES
	CS
	SS
	DS
	FS

	}
	if k := ft.OutSlice()[0].Kind_ & abi.KindMask; k == abi.Float32 || k == abi.Float64 {
		// In cdecl and stdcall, float results are returned in
		// ST(0). In fastcall, they're returned in XMM0.
		// Either way, it's not AX.
		panic("compileCallback: float results not supported")
	}
	if intArgRegs == 0 {
		// Make room for the uintptr-sized result.
		// If there are argument registers, the return value will