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285 lines (253 loc) · 7.02 KB
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// Copyright 2013 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 ir
// This file defines the Const SSA value type.
import (
"fmt"
"go/constant"
"go/types"
"strconv"
"strings"
"golang.org/x/exp/typeparams"
"honnef.co/go/tools/go/types/typeutil"
)
// NewConst returns a new constant of the specified value and type.
// val must be valid according to the specification of Const.Value.
func NewConst(val constant.Value, typ types.Type) *Const {
return &Const{
register: register{
typ: typ,
},
Value: val,
}
}
// intConst returns an 'int' constant that evaluates to i.
// (i is an int64 in case the host is narrower than the target.)
func intConst(i int64) *Const {
return NewConst(constant.MakeInt64(i), tInt)
}
// nilConst returns a nil constant of the specified type, which may
// be any reference type, including interfaces.
func nilConst(typ types.Type) *Const {
return NewConst(nil, typ)
}
// stringConst returns a 'string' constant that evaluates to s.
func stringConst(s string) *Const {
return NewConst(constant.MakeString(s), tString)
}
// zeroConst returns a new "zero" constant of the specified type.
func zeroConst(t types.Type) Constant {
if _, ok := t.Underlying().(*types.Interface); ok && !typeparams.IsTypeParam(t) {
// Handle non-generic interface early to simplify following code.
return nilConst(t)
}
tset := typeutil.NewTypeSet(t)
switch typ := tset.CoreType().(type) {
case *types.Struct:
values := make([]Value, typ.NumFields())
for i := 0; i < typ.NumFields(); i++ {
values[i] = zeroConst(typ.Field(i).Type())
}
return &AggregateConst{
register: register{typ: t},
Values: values,
}
case *types.Tuple:
values := make([]Value, typ.Len())
for i := 0; i < typ.Len(); i++ {
values[i] = zeroConst(typ.At(i).Type())
}
return &AggregateConst{
register: register{typ: t},
Values: values,
}
}
isNillable := func(term *types.Term) bool {
switch typ := term.Type().Underlying().(type) {
case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature, *typeutil.Iterator:
return true
case *types.Basic:
switch typ.Kind() {
case types.UnsafePointer, types.UntypedNil:
return true
default:
return false
}
default:
return false
}
}
isInfo := func(info types.BasicInfo) func(*types.Term) bool {
return func(term *types.Term) bool {
basic, ok := term.Type().Underlying().(*types.Basic)
if !ok {
return false
}
return (basic.Info() & info) != 0
}
}
isArray := func(term *types.Term) bool {
_, ok := term.Type().Underlying().(*types.Array)
return ok
}
switch {
case tset.All(isInfo(types.IsNumeric)):
return NewConst(constant.MakeInt64(0), t)
case tset.All(isInfo(types.IsString)):
return NewConst(constant.MakeString(""), t)
case tset.All(isInfo(types.IsBoolean)):
return NewConst(constant.MakeBool(false),
8000
t)
case tset.All(isNillable):
return nilConst(t)
case tset.All(isArray):
var k ArrayConst
k.setType(t)
return &k
default:
var k GenericConst
k.setType(t)
return &k
}
}
func (c *Const) RelString(from *types.Package) string {
var p string
if c.Value == nil {
p = "nil"
} else if c.Value.Kind() == constant.String {
v := constant.StringVal(c.Value)
const max = 20
// TODO(adonovan): don't cut a rune in half.
if len(v) > max {
v = v[:max-3] + "..." // abbreviate
}
p = strconv.Quote(v)
} else {
p = c.Value.String()
}
return fmt.Sprintf("Const <%s> {%s}", relType(c.Type(), from), p)
}
func (c *Const) String() string {
if c.block == nil {
// Constants don't have a block till late in the compilation process. But we want to print consts during
// debugging.
return c.RelString(nil)
}
return c.RelString(c.Parent().pkg())
}
func (v *ArrayConst) RelString(pkg *types.Package) string {
return fmt.Sprintf("ArrayConst <%s>", relType(v.Type(), pkg))
}
func (v *ArrayConst) String() string {
return v.RelString(v.Parent().pkg())
}
func (v *AggregateConst) RelString(pkg *types.Package) string {
values := make([]string, len(v.Values))
for i, v := range v.Values {
if v != nil {
values[i] = v.Name()
} else {
values[i] = "nil"
}
}
return fmt.Sprintf("AggregateConst <%s> (%s)", relType(v.Type(), pkg), strings.Join(values, ", "))
}
func (v *AggregateConst) String() string {
if v.block == nil {
return v.RelString(nil)
}
return v.RelString(v.Parent().pkg())
}
func (v *GenericConst) RelString(pkg *types.Package) string {
return fmt.Sprintf("GenericConst <%s>", relType(v.Type(), pkg))
}
func (v *GenericConst) String() string {
return v.RelString(v.Parent().pkg())
}
// IsNil returns true if this constant represents a typed or untyped nil value.
func (c *Const) IsNil() bool {
return c.Value == nil
}
// Int64 returns the numeric value of this constant truncated to fit
// a signed 64-bit integer.
func (c *Const) Int64() int64 {
switch x := constant.ToInt(c.Value); x.Kind() {
case constant.Int:
if i, ok := constant.Int64Val(x); ok {
return i
}
return 0
case constant.Float:
f, _ := constant.Float64Val(x)
return int64(f)
}
panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}
// Uint64 returns the numeric value of this constant truncated to fit
// an unsigned 64-bit integer.
func (c *Const) Uint64() uint64 {
switch x := constant.ToInt(c.Value); x.Kind() {
case constant.Int:
if u, ok := constant.Uint64Val(x); ok {
return u
}
return 0
case constant.Float:
f, _ := constant.Float64Val(x)
return uint64(f)
}
panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}
// Float64 returns the numeric value of this constant truncated to fit
// a float64.
func (c *Const) Float64() float64 {
f, _ := constant.Float64Val(c.Value)
return f
}
// Complex128 returns the complex value of this constant truncated to
// fit a complex128.
func (c *Const) Complex128() complex128 {
re, _ := constant.Float64Val(constant.Real(c.Value))
im, _ := constant.Float64Val(constant.Imag(c.Value))
return complex(re, im)
}
func (c *Const) equal(o Constant) bool {
// TODO(dh): don't use == for types, this will miss identical pointer types, among others
oc, ok := o.(*Const)
if !ok {
return false
}
return c.typ == oc.typ && c.Value == oc.Value
}
func (c *AggregateConst) equal(o Constant) bool {
oc, ok := o.(*AggregateConst)
if !ok {
return false
}
// TODO(dh): don't use == for types, this will miss identical pointer types, among others
if c.typ != oc.typ {
return false
}
for i, v := range c.Values {
if !v.(Constant).equal(oc.Values[i].(Constant)) {
return false
}
}
return true
}
func (c *ArrayConst) equal(o Constant) bool {
oc, ok := o.(*ArrayConst)
if !ok {
return false
}
// TODO(dh): don't use == for types, this will miss identical pointer types, among others
return c.typ == oc.typ
}
func (c *GenericConst) equal(o Constant) bool {
oc, ok := o.(*GenericConst)
if !ok {
return false
}
// TODO(dh): don't use == for types, this will miss identical pointer types, among others
return c.typ == oc.typ
}