M3:  "mmx3",
	M4:  "mmx4",
	M5:  "mmx5",
	M6:  "mmx6",
	M7:  "mmx7",
	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",

	// TODO: Maybe the constants are named wrong.
	SPB: "spl",
	BPB: "bpl",

	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",
	DS:   "%ds",
	ES:   "%es",

	// "VMOVQ r/m64, xmm1"/6E vs "VMOVQ xmm2/m64, xmm1"/7E with mem operand.
	VMOVQ (AX), X20           // 62e1fd086e20 or 62e1fe087e20
	VMOVQ 7(DX), X20          // 62e1fd086ea207000000 or 62e1fe087ea207000000
	VMOVQ -15(R11)(CX*1), X20 // 62c1fd086ea40bf1ffffff or 62c1fe087ea40bf1ffffff
	VMOVQ (SP)(AX*2), X20     // 62e1fd086e2444 or 62e1fe087e2444
	// "VMOVQ xmm1, r/m64"/7E vs "VMOVQ xmm1, xmm2/m64"/D6 with mem operand.

_0args:

	// Call stdcall function.
	CALL	AX

	ADDQ	$(const_maxArgs*8), SP

	// Return result.
	MOVQ	0(SP), CX
	MOVQ	8(SP), SP
	MOVQ	AX, libcall_r1(CX)
	// Floating point return values are returned in XMM0. Setting r2 to this
	// value in case this call returned a floating point value. For details,
	// see https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention
	MOVQ    X0, libcall_r2(CX)

	// GetLastError().

	xArgSTi          // arg ST(i) with +i in opcode
	xArgSreg         // arg Sreg
	xArgTR0dashTR7   // arg TR0-TR7
	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

	}
	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

					// Calculate the addend as the offset into the section.
					//
					// The rip-relative offset stored in the object file is encoded
					// as follows:
					//
					//    movsd	0x00000360(%rip),%xmm0
					//
					// To get the absolute address of the value this rip-relative address is pointing
					// to, we must add the address of the next instruction to it. This is done by

	{Zr_m_xm_nr, 1, argList{Ymr, Ym}},  // 0x7f MMX MOVQ
	{Zm_r_xm_nr, 2, argList{Yxr, Ymr}}, // Pf2, 0xd6 MOVDQ2Q
	{Zm_r_xm_nr, 2, argList{Yxm, Yxr}}, // Pf3, 0x7e MOVQ xmm1/m64 -> xmm2
	{Zr_m_xm_nr, 2, argList{Yxr, Yxm}}, // Pe, 0xd6 MOVQ xmm1 -> xmm2/m64

	// valid only in 64-bit mode, usually with 64-bit prefix
	{Zr_m, 1, argList{Yrl, Yml}},      // 0x89
	{Zm_r, 1, argList{Yml, Yrl}},      // 0x8b

package x86

// VEX instructions that come in two forms:
//	VTHING xmm2/m128, xmmV, xmm1
//	VTHING ymm2/m256, ymmV, ymm1
//
// The opcode array in the corresponding Optab entry
// should contain the (VEX prefixes, opcode byte) pair
// for each of the two forms.
// For example, the entries for VPXOR are:
//
//	VPXOR xmm2/m128, xmmV, xmm1
//	VEX.NDS.128.66.0F.WIG EF /r
//
//	VPXOR ymm2/m256, ymmV, ymm1