Load(aX, RAX)
	case 2:
		Comment(fmt.Sprintf("%s = 2×%s×%s", r, aX, bX))
		Load(aX, RAX)
		SHLQ(Imm(1), RAX)
	default:
		panic("unsupported i value")
	}
	MULQ(mustAddr(bX)) // RDX, RAX = RAX * bX
	MOVQ(RAX, r.lo)
	MOVQ(RDX, r.hi)
}

// addMul64 sets r to r + i * aX * bX.
func addMul64(r uint128, i uint64, aX, bX namedComponent) {
	switch i {
	case 1:
		Comment(fmt.Sprintf("%s += %s×%s", r, aX, bX))

type regmmst struct {
	mmst_reg  [10]int8
	mmst_rsrv [6]int8
}

type regxmm struct {
	xmm_reg [16]int8
}

type regs64 struct {
	rax    uint64
	rbx    uint64
	rcx    uint64
	rdx    uint64
	rdi    uint64
	rsi    uint64
	rbp    uint64
	rsp    uint64
	r8     uint64
	r9     uint64
	r10    uint64
	r11    uint64
	r12    uint64
	r13    uint64
	r14    uint64

	R14      uint64
	R13      uint64
	R12      uint64
	Rbp      uint64
	Rbx      uint64
	R11      uint64
	R10      uint64
	R9       uint64
	R8       uint64
	Rax      uint64
	Rcx      uint64
	Rdx      uint64
	Rsi      uint64
	Rdi      uint64
	Orig_rax uint64
	Rip      uint64
	Cs       uint64
	Eflags   uint64
	Rsp      uint64
	Ss       uint64
	Fs_base  uint64
	Gs_base  uint64

	// invoke INT3. The debugger should write the argument
	// frame for the call at SP, set up argument registers, push
	// the trapping PC on the stack, set the PC to the function to
	// call, set RDX to point to the closure (if a closure call),
	// and resume execution.
	//
	// If the function returns, this will set R12 to 1 and invoke
	// INT3. The debugger can then inspect any return value saved

		{"PtraceRegs.R9", Field, 0},
		{"PtraceRegs.Rax", Field, 0},
		{"PtraceRegs.Rbp", Field, 0},
		{"PtraceRegs.Rbx", Field, 0},
		{"PtraceRegs.Rcx", Field, 0},
		{"PtraceRegs.Rdi", Field, 0},
		{"PtraceRegs.Rdx", Field, 0},
		{"PtraceRegs.Rip", Field, 0},
		{"PtraceRegs.Rsi", Field, 0},
		{"PtraceRegs.Rsp", Field, 0},
		{"PtraceRegs.Ss", Field, 0},
		{"PtraceRegs.Uregs", Field, 0},
		{"PtraceRegs.Xcs", Field, 0},