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) {

	o1 |= uint32(p.To.Reg&0x1f) << 21                          // RT
	o1 |= uint32(p.From.Reg&0x1f) << 16                        // RA
	o0 |= uint32((p.RestArgs[0].Addr.Offset>>16)&0x3ffff) << 0 // si0
	o1 |= uint32(p.RestArgs[0].Addr.Offset&0xffff) << 0        // si1
	o0 |= uint32(p.RestArgs[1].Addr.Offset&0x1) << 20          // R
	out[1] = o1
	out[0] = o0
}

// pextd RA,RS,RB

		// 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 {

	ctxt.Diag("invalid encoding for argument %v", p)
}

func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
	for p := sym.Func().Text; p != nil; p = p.Link {
		checkaddr(ctxt, p, &p.From)
		for _, v := range p.RestArgs {
			checkaddr(ctxt, p, &v.Addr)
		}
		checkaddr(ctxt, p, &p.To)

		if ctxt.Arch.Progedit != nil {
			ctxt.Arch.Progedit(ctxt, p, newprog)
		}
		if p.To.Type != TYPE_BRANCH {
			continue
		}

		p1.From.Sym = ctxt.Lookup("_GLOBAL_OFFSET_TABLE_")
		p1.To.Type = obj.TYPE_REG
		p1.To.Reg = REG_BX

		p2.As = p.As
		p2.Scond = p.Scond
		p2.From = p.From
		if p.RestArgs != nil {
			p2.RestArgs = append(p2.RestArgs, p.RestArgs...)
		}
		p2.Reg = p.Reg
		p2.To = p.To
		// p.To.Type was set to TYPE_BRANCH above, but that makes checkaddr
		// in ../pass.go complain, so set it back to TYPE_MEM here, until p2

		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