go softfloat 源码
golang softfloat 代码
文件路径：/src/cmd/compile/internal/ssa/softfloat.go
// Copyright 2017 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/types"
"math"
)
func softfloat(f *Func) {
if !f.Config.SoftFloat {
return
}
newInt64 := false
for _, b := range f.Blocks {
for _, v := range b.Values {
if v.Type.IsFloat() {
f.unCache(v)
switch v.Op {
case OpPhi, OpLoad, OpArg:
if v.Type.Size() == 4 {
v.Type = f.Config.Types.UInt32
} else {
v.Type = f.Config.Types.UInt64
}
case OpConst32F:
v.Op = OpConst32
v.Type = f.Config.Types.UInt32
v.AuxInt = int64(int32(math.Float32bits(auxTo32F(v.AuxInt))))
case OpConst64F:
v.Op = OpConst64
v.Type = f.Config.Types.UInt64
case OpNeg32F:
arg0 := v.Args[0]
v.reset(OpXor32)
v.Type = f.Config.Types.UInt32
v.AddArg(arg0)
mask := v.Block.NewValue0(v.Pos, OpConst32, v.Type)
mask.AuxInt = -0x80000000
v.AddArg(mask)
case OpNeg64F:
arg0 := v.Args[0]
v.reset(OpXor64)
v.Type = f.Config.Types.UInt64
v.AddArg(arg0)
mask := v.Block.NewValue0(v.Pos, OpConst64, v.Type)
mask.AuxInt = -0x8000000000000000
v.AddArg(mask)
case OpRound32F:
v.Op = OpCopy
v.Type = f.Config.Types.UInt32
case OpRound64F:
v.Op = OpCopy
v.Type = f.Config.Types.UInt64
}
newInt64 = newInt64 || v.Type.Size() == 8
} else if (v.Op == OpStore || v.Op == OpZero || v.Op == OpMove) && v.Aux.(*types.Type).IsFloat() {
switch size := v.Aux.(*types.Type).Size(); size {
case 4:
v.Aux = f.Config.Types.UInt32
case 8:
v.Aux = f.Config.Types.UInt64
newInt64 = true
default:
v.Fatalf("bad float type with size %d", size)
}
}
}
}
if newInt64 && f.Config.RegSize == 4 {
// On 32bit arch, decompose Uint64 introduced in the switch above.
decomposeBuiltIn(f)
applyRewrite(f, rewriteBlockdec64, rewriteValuedec64, removeDeadValues)
}
}
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