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// Copyright 2015 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 (
"fmt"
"math"
)
// A Value represents a value in the SSA representation of the program.
// The ID and Type fields must not be modified. The remainder may be modified
// if they preserve the value of the Value (e.g. changing a (mul 2 x) to an (add x x)).
type Value struct {
// A unique identifier for the value. For performance we allocate these IDs
// densely starting at 1. There is no guarantee that there won't be occasional holes, though.
ID ID
// The operation that computes this value. See op.go.
Op Op
// The type of this value. Normally this will be a Go type, but there
// are a few other pseudo-types, see type.go.
Type Type
// Auxiliary info for this value. The type of this information depends on the opcode and type.
// AuxInt is used for integer values, Aux is used for other values.
// Floats are stored in AuxInt using math.Float64bits(f).
AuxInt int64
Aux interface{}
// Arguments of this value
Args []*Value
// Containing basic block
Block *Block
// Source line number
Line int32
// Use count. Each appearance in Value.Args and Block.Control counts once.
Uses int32
// Storage for the first three args
argstorage [3]*Value
}
// Examples:
// Opcode aux args
// OpAdd nil 2
// OpConst string 0 string constant
// OpConst int64 0 int64 constant
// OpAddcq int64 1 amd64 op: v = arg[0] + constant
// short form print. Just v#.
func (v *Value) String() string {
if v == nil {
return "nil" // should never happen, but not panicking helps with debugging
}
return fmt.Sprintf("v%d", v.ID)
}
func (v *Value) AuxInt8() int8 {
if opcodeTable[v.Op].auxType != auxInt8 {
v.Fatalf("op %s doesn't have an int8 aux field", v.Op)
}
return int8(v.AuxInt)
}
func (v *Value) AuxInt16() int16 {
if opcodeTable[v.Op].auxType != auxInt16 {
v.Fatalf("op %s doesn't have an int16 aux field", v.Op)
}
return int16(v.AuxInt)
}
func (v *Value) AuxInt32() int32 {
if opcodeTable[v.Op].auxType != auxInt32 {
v.Fatalf("op %s doesn't have an int32 aux field", v.Op)
}
return int32(v.AuxInt)
}
func (v *Value) AuxFloat() float64 {
if opcodeTable[v.Op].auxType != auxFloat32 && opcodeTable[v.Op].auxType != auxFloat64 {
v.Fatalf("op %s doesn't have a float aux field", v.Op)
}
return math.Float64frombits(uint64(v.AuxInt))
}
func (v *Value) AuxValAndOff() ValAndOff {
if opcodeTable[v.Op].auxType != auxSymValAndOff {
v.Fatalf("op %s doesn't have a ValAndOff aux field", v.Op)
}
return ValAndOff(v.AuxInt)
}
// long form print. v# = opcode <type> [aux] args [: reg]
func (v *Value) LongString() string {
s := fmt.Sprintf("v%d = %s", v.ID, v.Op)
s += " <" + v.Type.String() + ">"
s += v.auxString()
for _, a := range v.Args {
s += fmt.Sprintf(" %v", a)
}
r := v.Block.Func.RegAlloc
if int(v.ID) < len(r) && r[v.ID] != nil {
s += " : " + r[v.ID].Name()
}
return s
}
func (v *Value) auxString() string {
switch opcodeTable[v.Op].auxType {
case auxBool:
if v.AuxInt == 0 {
return " [false]"
} else {
return " [true]"
}
case auxInt8:
return fmt.Sprintf(" [%d]", v.AuxInt8())
case auxInt16:
return fmt.Sprintf(" [%d]", v.AuxInt16())
case auxInt32:
return fmt.Sprintf(" [%d]", v.AuxInt32())
case auxInt64, auxInt128:
return fmt.Sprintf(" [%d]", v.AuxInt)
case auxSizeAndAlign:
return fmt.Sprintf(" [%s]", SizeAndAlign(v.AuxInt))
case auxFloat32, auxFloat64:
return fmt.Sprintf(" [%g]", v.AuxFloat())
case auxString:
return fmt.Sprintf(" {%q}", v.Aux)
case auxSym:
if v.Aux != nil {
return fmt.Sprintf(" {%v}", v.Aux)
}
case auxSymOff, auxSymInt32:
s := ""
if v.Aux != nil {
s = fmt.Sprintf(" {%v}", v.Aux)
}
if v.AuxInt != 0 {
s += fmt.Sprintf(" [%v]", v.AuxInt)
}
return s
case auxSymValAndOff:
s := ""
if v.Aux != nil {
s = fmt.Sprintf(" {%v}", v.Aux)
}
return s + fmt.Sprintf(" [%s]", v.AuxValAndOff())
case auxSymSizeAndAlign:
s := ""
if v.Aux != nil {
s = fmt.Sprintf(" {%v}", v.Aux)
}
return s + fmt.Sprintf(" [%s]", SizeAndAlign(v.AuxInt))
}
return ""
}
func (v *Value) AddArg(w *Value) {
if v.Args == nil {
v.resetArgs() // use argstorage
}
v.Args = append(v.Args, w)
w.Uses++
}
func (v *Value) AddArgs(a ...*Value) {
if v.Args == nil {
v.resetArgs() // use argstorage
}
v.Args = append(v.Args, a...)
for _, x := range a {
x.Uses++
}
}
func (v *Value) SetArg(i int, w *Value) {
v.Args[i].Uses--
v.Args[i] = w
w.Uses++
}
func (v *Value) RemoveArg(i int) {
v.Args[i].Uses--
copy(v.Args[i:], v.Args[i+1:])
v.Args[len(v.Args)-1] = nil // aid GC
v.Args = v.Args[:len(v.Args)-1]
}
func (v *Value) SetArgs1(a *Value) {
v.resetArgs()
v.AddArg(a)
}
func (v *Value) SetArgs2(a *Value, b *Value) {
v.resetArgs()
v.AddArg(a)
v.AddArg(b)
}
func (v *Value) resetArgs() {
for _, a := range v.Args {
a.Uses--
}
v.argstorage[0] = nil
v.argstorage[1] = nil
v.argstorage[2] = nil
v.Args = v.argstorage[:0]
}
func (v *Value) reset(op Op) {
v.Op = op
v.resetArgs()
v.AuxInt = 0
v.Aux = nil
}
// copyInto makes a new value identical to v and adds it to the end of b.
func (v *Value) copyInto(b *Block) *Value {
c := b.NewValue0(v.Line, v.Op, v.Type)
c.Aux = v.Aux
c.AuxInt = v.AuxInt
c.AddArgs(v.Args...)
for _, a := range v.Args {
if a.Type.IsMemory() {
v.Fatalf("can't move a value with a memory arg %s", v.LongString())
}
}
return c
}
func (v *Value) Logf(msg string, args ...interface{}) { v.Block.Logf(msg, args...) }
func (v *Value) Log() bool { return v.Block.Log() }
func (v *Value) Fatalf(msg string, args ...interface{}) {
v.Block.Func.Config.Fatalf(v.Line, msg, args...)
}
// isGenericIntConst returns whether v is a generic integer constant.
func (v *Value) isGenericIntConst() bool {
return v != nil && (v.Op == OpConst64 || v.Op == OpConst32 || v.Op == OpConst16 || v.Op == OpConst8)
}
// ExternSymbol is an aux value that encodes a variable's
// constant offset from the static base pointer.
type ExternSymbol struct {
Typ Type // Go type
Sym fmt.Stringer // A *gc.Sym referring to a global variable
// Note: the offset for an external symbol is not
// calculated until link time.
}
// ArgSymbol is an aux value that encodes an argument or result
// variable's constant offset from FP (FP = SP + framesize).
type ArgSymbol struct {
Typ Type // Go type
Node GCNode // A *gc.Node referring to the argument/result variable.
}
// AutoSymbol is an aux value that encodes a local variable's
// constant offset from SP.
type AutoSymbol struct {
Typ Type // Go type
Node GCNode // A *gc.Node referring to a local (auto) variable.
}
func (s *ExternSymbol) String() string {
return s.Sym.String()
}
func (s *ArgSymbol) String() string {
return s.Node.String()
}
func (s *AutoSymbol) String() string {
return s.Node.String()
}
// Reg returns the register assigned to v, in cmd/internal/obj/$ARCH numbering.
func (v *Value) Reg() int16 {
reg := v.Block.Func.RegAlloc[v.ID]
if reg == nil {
v.Fatalf("nil register for value: %s\n%s\n", v.LongString(), v.Block.Func)
}
return reg.(*Register).objNum
}
// Reg0 returns the register assigned to the first output of v, in cmd/internal/obj/$ARCH numbering.
func (v *Value) Reg0() int16 {
reg := v.Block.Func.RegAlloc[v.ID].(LocPair)[0]
if reg == nil {
v.Fatalf("nil first register for value: %s\n%s\n", v.LongString(), v.Block.Func)
}
return reg.(*Register).objNum
}
// Reg1 returns the register assigned to the second output of v, in cmd/internal/obj/$ARCH numbering.
func (v *Value) Reg1() int16 {
reg := v.Block.Func.RegAlloc[v.ID].(LocPair)[1]
if reg == nil {
v.Fatalf("nil second register for value: %s\n%s\n", v.LongString(), v.Block.Func)
}
return reg.(*Register).objNum
}
func (v *Value) RegName() string {
reg := v.Block.Func.RegAlloc[v.ID]
if reg == nil {
v.Fatalf("nil register for value: %s\n%s\n", v.LongString(), v.Block.Func)
}
return reg.(*Register).name
}