phis = phis[:0]
			for i := len(b.Values) - 1; i >= 0; i-- {
				v := b.Values[i]
				live.remove(v.ID)
				if v.Op == OpPhi {
					// Save phi for later.
					// Note: its args might need a stack slot even though
					// the phi itself doesn't. So don't use needSlot.
					if !v.Type.IsMemory() && !v.Type.IsVoid() {
						phis = append(phis, v)
					}
					continue
				}

	}
}

// newPhiFor inserts a new Phi function into b,
// with all inputs set to v.
func newPhiFor(b *Block, v *Value) *Value {
	phiV := b.NewValue0(b.Pos, OpPhi, v.Type)

	for range b.Preds {
		phiV.AddArg(v)
	}
	return phiV
}

// rewriteNewPhis updates newphis[h] to record all places where the new phi function inserted

			// to phi to refer to the corresponding phi arg instead.
			// phi used to be evaluated prior to this block,
			// and now it is evaluated in this block.
			for _, v := range phi.Block.Values {
				if v.Op != OpPhi || v == phi {
					continue
				}
				for j, a := range v.Args {
					if a == phi {
						v.SetArg(j, phi.Args[j])
					}
				}
			}
			if phi.Uses != 0 {

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"cmd/compile/internal/types"
	"sort"
)

// decompose converts phi ops on compound builtin types into phi
// ops on simple types, then invokes rewrite rules to decompose
// other ops on those types.
func decomposeBuiltIn(f *Func) {
	// Decompose phis
	for _, b := range f.Blocks {

	case "amd64":
		const maxcost = 2
		phi := 0
		other := 0
		for _, v := range post.Values {
			if v.Op == OpPhi {
				// Each phi results in CondSelect, which lowers into CMOV,
				// CMOV has latency >1 on most CPUs.
				phi++
			}
			for _, x := range v.Args {
				if x.Block == no || x.Block == yes {
					other++
				}
			}
		}
		cost := phi * 1
		if phi > 1 {

func (fwdRefAux) CanBeAnSSAAux() {}

// insertPhis finds all the places in the function where a phi is
// necessary and inserts them.
// Uses FwdRef ops to find all uses of variables, and s.defvars to find
// all definitions.
// Phi values are inserted, and all FwdRefs are changed to a Copy
// of the appropriate phi or definition.
// TODO: make this part of cmd/compile/internal/ssa somehow?
func (s *state) insertPhis() {

					// reaching an op, but some ops can take
					// multiple pointers (e.g. NeqPtr, Phi etc.).
					// This is rare, so just propagate the first
					// value to keep things simple.
					used.Add(n)
					changed = true
				}
			}
		}
		if node == nil {
			return
		}
		if addr[v] == nil {
			// The address of an auto reaches this op.
			addr[v] = node
			changed = true
			return
		}

	work = append(work, bp{block: f.Entry})

	// map from value ID to known non-nil version of that value ID
	// (in the current dominator path being walked). This slice is updated by
	// walkStates to maintain the known non-nil values.
	// If there is extrinsic information about non-nil-ness, this map
	// points a value to itself. If a value is known non-nil because we
	// already did a nil check on it, it points to the nil check operation.

			If("bool2", "extra", "exit")),
		Bloc("extra",
			// prevent fuse from eliminating this block
			Valu("store", OpStore, types.TypeMem, 0, ptrType, "ptr1", "nilptr", "mem"),
			Goto("exit")),
		Bloc("exit",
			Valu("phi", OpPhi, types.TypeMem, 0, nil, "mem", "store"),
			Exit("phi")))

	CheckFunc(fun.f)
	// we need the opt here to rewrite the user nilcheck
	opt(fun.f)
	nilcheckelim(fun.f)

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains rules to decompose [u]int64 types on 32-bit
// architectures. These rules work together with the decomposeBuiltIn
// pass which handles phis of these typ.

(Int64Hi (Int64Make hi _)) => hi
(Int64Lo (Int64Make _ lo)) => lo