assert(!hoist_params->lhs_args[kv.second]);
      assert(!hoist_params->rhs_args[kv.second]);

      if (hoist_params->scalar_operand_idx == 1) {
        hoist_params->lhs_args[kv.second] = kv.first;
        hoist_params->rhs_args[kv.second] = identity_const;
      } else {
        assert(hoist_params->scalar_operand_idx == 0);
        hoist_params->lhs_args[kv.second] = identity_const;

// return the first source operand in p.RestArgs.
// In combination with Prog.From and Prog.To it makes common 3 operand
// case easier to use.
func (p *Prog) GetFrom3() *Addr {
	for i := range p.RestArgs {
		if p.RestArgs[i].Pos == Source {
			return &p.RestArgs[i].Addr
		}
	}
	return nil
}

// AddRestSource assigns []Args{{a, Source}} to p.RestArgs.
func (p *Prog) AddRestSource(a Addr) {

		// Should not happen but might as well show it if it does.
		fmt.Fprintf(w, "%s%v", sep, Rconv(int(p.Reg)))
		sep = ", "
	}
	for i := range p.RestArgs {
		if p.RestArgs[i].Pos == Source {
			io.WriteString(w, sep)
			WriteDconv(w, p, &p.RestArgs[i].Addr)
			sep = ", "
		}
	}

	if p.As == ATEXT {
		// If there are attributes, print them. Otherwise, skip the comma.

	//                                "ADDEX R3, R4, $3, R5"
	case AVSHASIGMAW, AVSHASIGMAD, AADDEX, AXXSLDWI, AXXPERMDI:
		if len(p.RestArgs) == 2 && p.Reg == 0 && p.RestArgs[0].Addr.Type == obj.TYPE_CONST && p.RestArgs[1].Addr.Type == obj.TYPE_REG {
			p.Reg = p.RestArgs[1].Addr.Reg
			p.RestArgs = p.RestArgs[:1]
		}
	}

	if c.ctxt.Headtype == objabi.Haix {
		c.rewriteToUseTOC(p)
	} else if c.ctxt.Flag_dynlink {

		return &optab[p.Optab-1]
	}
	if len(p.RestArgs) > 3 {
		c.ctxt.Diag("too many RestArgs: got %v, maximum is 3\n", len(p.RestArgs))
		return nil
	}

	// Initialize classes for all arguments.
	p.From.Class = int8(c.aclass(&p.From) + 1)
	p.To.Class = int8(c.aclass(&p.To) + 1)
	for i := range p.RestArgs {
		p.RestArgs[i].Addr.Class = int8(c.aclass(&p.RestArgs[i].Addr) + 1)
	}

					return
				}
				// For ARM64 CASP-like instructions, its 2nd destination operand is register pair(Rt, Rt+1) that can
				// not fit into prog.RegTo2, so save it to the prog.RestArgs.
				prog.AddRestDest(a[2])
			default:
				prog.From = a[0]
				prog.Reg = p.getRegister(prog, op, &a[1])
				prog.To = a[2]
			}
		case sys.I386:
			prog.From = a[0]
			prog.AddRestSource(a[1])

type Optab struct {
	as    obj.As // Opcode
	a1    uint8  // p.From argument (obj.Addr). p is of type obj.Prog.
	a2    uint8  // p.Reg argument (int16 Register)
	a3    uint8  // p.RestArgs[0]  (obj.AddrPos)
	a4    uint8  // p.RestArgs[1]
	a5    uint8  // p.RestARgs[2]
	a6    uint8  // p.To (obj.Addr)
	type_ int8   // cases in asmout below. E.g., 44 = st r,(ra+rb); 45 = ld (ra+rb), r
	size  int8   // Text space in bytes to lay operation

	}

	// 2nd destination operand
	a5 := C_NONE
	if p.RegTo2 != 0 {
		a5 = C_REG
	}

	// 3rd source operand
	a3 := C_NONE
	if len(p.RestArgs) > 0 {
		a3 = int(p.RestArgs[0].Class)
		if a3 == 0 {
			a3 = c.aclass(&p.RestArgs[0].Addr) + 1
			p.RestArgs[0].Class = int8(a3)
		}
		a3--
	}

	ops := oprange[p.As&obj.AMask]
	c1 := &xcmp[a1]
	c4 := &xcmp[a4]
	for i := range ops {

func unpackOps4(p *obj.Prog) (arg0, arg1, arg2, dst *obj.Addr) {
	return &p.From, &p.RestArgs[0].Addr, &p.RestArgs[1].Addr, &p.To
}

// unpackOps5 extracts 5 operands from p.
func unpackOps5(p *obj.Prog) (arg0, arg1, arg2, arg3, dst *obj.Addr) {
	return &p.From, &p.RestArgs[0].Addr, &p.RestArgs[1].Addr, &p.RestArgs[2].Addr, &p.To

const (
	REGFROM = 1
)

type Optab struct {
	as    obj.As
	a1    uint8 // Prog.From
	a2    uint8 // 2nd source operand, Prog.Reg or Prog.RestArgs[XXX]
	a3    uint8 // 3rd source operand, Prog.RestArgs[XXX]
	a4    uint8 // Prog.To
	a5    uint8 // 2nd destination operand, Prog.RegTo2 or Prog.RestArgs[XXX]
	type_ int8
	size_ int8 // the value of this field is not static, use the size() method to return the value
	param int16
	flag  int8