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cmd/compile: fix zero extend after float->int conversion

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Don't do direct loads from argument slots if the sizes don't match.
This prevents us from loading from a float32 using a uint64 load
during expressions like uint64(math.float32Bits(f)) where f is a float32 arg.

Fixes #25322

Change-Id: I3887d76f78c844ba546243e7721d811c3d4a9700
Reviewed-on: https://go-review.googlesource.com/112637
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall 2018-05-10 10:15:52 -07:00 committed by Keith Randall
parent ef24fd739b
commit 599f56dc05
5 changed files with 53 additions and 13 deletions
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8
src/cmd/compile/internal/ssa/gen/AMD64.rules
View file

@ -2396,10 +2396,10 @@
// Load args directly into the register class where it will be used.
// We do this by just modifying the type of the Arg.
(MOVQf2i <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVLf2i <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVQi2f <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVLi2f <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVQf2i <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVLf2i <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVQi2f <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
(MOVLi2f <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
// LEAQ is rematerializeable, so this helps to avoid register spill.
// See issue 22947 for details

2
src/cmd/compile/internal/ssa/gen/AMD64Ops.go
View file

@ -482,7 +482,7 @@ func init() {
{name: "MOVQi2f", argLength: 1, reg: gpfp, typ: "Float64"}, // move 64 bits from int to float reg
{name: "MOVQf2i", argLength: 1, reg: fpgp, typ: "UInt64"}, // move 64 bits from float to int reg
{name: "MOVLi2f", argLength: 1, reg: gpfp, typ: "Float32"}, // move 32 bits from int to float reg
{name: "MOVLf2i", argLength: 1, reg: fpgp, typ: "UInt32"}, // move 32 bits from float to int reg
{name: "MOVLf2i", argLength: 1, reg: fpgp, typ: "UInt32"}, // move 32 bits from float to int reg, zero extend
{name: "PXOR", argLength: 2, reg: fp21, asm: "PXOR", commutative: true, resultInArg0: true}, // exclusive or, applied to X regs for float negation.

32
src/cmd/compile/internal/ssa/rewriteAMD64.go
View file

@ -13143,8 +13143,8 @@ func rewriteValueAMD64_OpAMD64MOVLatomicload_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
b := v.Block
_ = b
// match: (MOVLf2i <t> (Arg [off] {sym}))
// cond:
// match: (MOVLf2i <t> (Arg <u> [off] {sym}))
// cond: t.Size() == u.Size()
// result: @b.Func.Entry (Arg <t> [off] {sym})
for {
t := v.Type
@ -13152,8 +13152,12 @@ func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
if v_0.Op != OpArg {
break
}
u := v_0.Type
off := v_0.AuxInt
sym := v_0.Aux
if !(t.Size() == u.Size()) {
break
}
b = b.Func.Entry
v0 := b.NewValue0(v.Pos, OpArg, t)
v.reset(OpCopy)
@ -13167,8 +13171,8 @@ func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVLi2f_0(v *Value) bool {
b := v.Block
_ = b
// match: (MOVLi2f <t> (Arg [off] {sym}))
// cond:
// match: (MOVLi2f <t> (Arg <u> [off] {sym}))
// cond: t.Size() == u.Size()
// result: @b.Func.Entry (Arg <t> [off] {sym})
for {
t := v.Type
@ -13176,8 +13180,12 @@ func rewriteValueAMD64_OpAMD64MOVLi2f_0(v *Value) bool {
if v_0.Op != OpArg {
break
}
u := v_0.Type
off := v_0.AuxInt
sym := v_0.Aux
if !(t.Size() == u.Size()) {
break
}
b = b.Func.Entry
v0 := b.NewValue0(v.Pos, OpArg, t)
v.reset(OpCopy)
@ -15520,8 +15528,8 @@ func rewriteValueAMD64_OpAMD64MOVQatomicload_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
b := v.Block
_ = b
// match: (MOVQf2i <t> (Arg [off] {sym}))
// cond:
// match: (MOVQf2i <t> (Arg <u> [off] {sym}))
// cond: t.Size() == u.Size()
// result: @b.Func.Entry (Arg <t> [off] {sym})
for {
t := v.Type
@ -15529,8 +15537,12 @@ func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
if v_0.Op != OpArg {
break
}
u := v_0.Type
off := v_0.AuxInt
sym := v_0.Aux
if !(t.Size() == u.Size()) {
break
}
b = b.Func.Entry
v0 := b.NewValue0(v.Pos, OpArg, t)
v.reset(OpCopy)
@ -15544,8 +15556,8 @@ func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
func rewriteValueAMD64_OpAMD64MOVQi2f_0(v *Value) bool {
b := v.Block
_ = b
// match: (MOVQi2f <t> (Arg [off] {sym}))
// cond:
// match: (MOVQi2f <t> (Arg <u> [off] {sym}))
// cond: t.Size() == u.Size()
// result: @b.Func.Entry (Arg <t> [off] {sym})
for {
t := v.Type
@ -15553,8 +15565,12 @@ func rewriteValueAMD64_OpAMD64MOVQi2f_0(v *Value) bool {
if v_0.Op != OpArg {
break
}
u := v_0.Type
off := v_0.AuxInt
sym := v_0.Aux
if !(t.Size() == u.Size()) {
break
}
b = b.Func.Entry
v0 := b.NewValue0(v.Pos, OpArg, t)
v.reset(OpCopy)

23
test/fixedbugs/issue25322.go Normal file
View file

@ -0,0 +1,23 @@
// cmpout
// 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.
// Missing zero extension when converting a float32
// to a uint64.
package main
import (
"fmt"
"math"
)
func Foo(v float32) {
fmt.Printf("%x\n", uint64(math.Float32bits(v)))
}
func main() {
Foo(2.0)
}

1
test/fixedbugs/issue25322.out Normal file
View file

@ -0,0 +1 @@
40000000