if symname == nil {
		symname = func(uint64) (string, uint64) { return "", 0 }
	}

	// Adjust opcode [sic].
	switch inst.Op {
	case FDIV, FDIVR, FSUB, FSUBR, FDIVP, FDIVRP, FSUBP, FSUBRP:
		// DC E0, DC F0: libopcodes swaps FSUBR/FSUB and FDIVR/FDIV, at least
		// if you believe the Intel manual is correct (the encoding is irregular as given;
		// libopcodes uses the more regular expected encoding).

	case FST, FSTP, FISTTP, FIST, FISTP, FBSTP:
		if len(args) == 1 {
			args = append(args, "st0")
		}

	case FLD, FXCH, FCOM, FCOMP, FIADD, FIMUL, FICOM, FICOMP, FISUBR, FIDIV, FUCOM, FUCOMP, FILD, FBLD, FADD, FMUL, FSUB, FSUBR, FISUB, FDIV, FDIVR, FIDIVR:
		if len(args) == 1 {
			args = []string{"st0", args[0]}
		}

	case MASKMOVDQU, MASKMOVQ, XLATB, OUTSB, OUTSW, OUTSD:
	FixSegment:
		for i := len(inst.Prefix) - 1; i >= 0; i-- {

	FSIN:            "FSIN",
	FSINCOS:         "FSINCOS",
	FSQRT:           "FSQRT",
	FST:             "FST",
	FSTP:            "FSTP",
	FSUB:            "FSUB",
	FSUBP:           "FSUBP",
	FSUBR:           "FSUBR",
	FSUBRP:          "FSUBRP",
	FTST:            "FTST",
	FUCOM:           "FUCOM",
	FUCOMI:          "FUCOMI",
	FUCOMIP:         "FUCOMIP",
	FUCOMP:          "FUCOMP",

	//TODO: FSTPT (R11)                     // 41db3b
	//TODO: FSUB F2, F0                     // d8e2
	//TODO: FSUB F3, F0                     // d8e3
	//TODO: FSUBR F0, F2                    // dcea
	//TODO: FSUBR F0, F3                    // dceb
	//TODO: FSUBS (BX)                      // d823
	//TODO: FSUBS (R11)                     // 41d823
	//TODO: FSUBL (BX)                      // dc23