src/cmd/compile/internal/ssa/numberlines.go

// Copyright 2018 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.

package ssa

import "cmd/compile/internal/ssa/ssaop"

// NotStmtBoundary reports whether a value with opcode op can never be a statement
// boundary. Such values don't correspond to a user's understanding of a
// statement boundary.
func NotStmtBoundary(op ssaop.Op) bool {
	switch op {
	case ssaop.OpCopy, ssaop.OpPhi, ssaop.OpVarDef, ssaop.OpVarLive, ssaop.OpUnknown, ssaop.OpFwdRef, ssaop.OpArg, ssaop.OpArgIntReg, ssaop.OpArgFloatReg:
		return true
	}
	return false
}

func (b *Block) FirstPossibleStmtValue() *Value {
	for _, v := range b.Values {
		if NotStmtBoundary(v.Op) {
			continue
		}
		return v
	}
	return nil
}