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cmd/compile: don't rewrite (CMP (AND x y) 0) to TEST if AND has other uses

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If the AND has other uses, we end up saving an argument to the AND
in another register, so we can use it for the TEST. No point in doing that.

Change-Id: I73444a6aeddd6f55e2328ce04d77c3e6cf4a83e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/241280
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 2020-07-07 09:32:12 -07:00
parent 8b8f926fc3
commit ef9c8a38ad
3 changed files with 128 additions and 40 deletions
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16
src/cmd/compile/internal/ssa/gen/AMD64.rules
View file

@ -1463,14 +1463,14 @@
(MULQconst [c] (NEGQ x)) && c != -(1<<31) -> (MULQconst [-c] x)
// checking AND against 0.
(CMPQconst (ANDQ x y) [0]) -> (TESTQ x y)
(CMPLconst (ANDL x y) [0]) -> (TESTL x y)
(CMPWconst (ANDL x y) [0]) -> (TESTW x y)
(CMPBconst (ANDL x y) [0]) -> (TESTB x y)
(CMPQconst (ANDQconst [c] x) [0]) -> (TESTQconst [c] x)
(CMPLconst (ANDLconst [c] x) [0]) -> (TESTLconst [c] x)
(CMPWconst (ANDLconst [c] x) [0]) -> (TESTWconst [int64(int16(c))] x)
(CMPBconst (ANDLconst [c] x) [0]) -> (TESTBconst [int64(int8(c))] x)
(CMPQconst a:(ANDQ x y) [0]) && a.Uses == 1 -> (TESTQ x y)
(CMPLconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTL x y)
(CMPWconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTW x y)
(CMPBconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTB x y)
(CMPQconst a:(ANDQconst [c] x) [0]) && a.Uses == 1 -> (TESTQconst [c] x)
(CMPLconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTLconst [c] x)
(CMPWconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTWconst [int64(int16(c))] x)
(CMPBconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTBconst [int64(int8(c))] x)
// Convert TESTx to TESTxconst if possible.
(TESTQ (MOVQconst [c]) x) && is32Bit(c) -> (TESTQconst [c] x)

128
src/cmd/compile/internal/ssa/rewriteAMD64.go
View file

@ -6924,26 +6924,42 @@ func rewriteValueAMD64_OpAMD64CMPBconst(v *Value) bool {
v.reset(OpAMD64FlagLT_ULT)
return true
}
// match: (CMPBconst (ANDL x y) [0])
// match: (CMPBconst a:(ANDL x y) [0])
// cond: a.Uses == 1
// result: (TESTB x y)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDL {
break
}
y := a.Args[1]
x := a.Args[0]
if !(a.Uses == 1) {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
v.reset(OpAMD64TESTB)
v.AddArg2(x, y)
return true
}
// match: (CMPBconst (ANDLconst [c] x) [0])
// match: (CMPBconst a:(ANDLconst [c] x) [0])
// cond: a.Uses == 1
// result: (TESTBconst [int64(int8(c))] x)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDLconst {
break
}
c := a.AuxInt
x := a.Args[0]
if !(a.Uses == 1) {
break
}
c := v_0.AuxInt
x := v_0.Args[0]
v.reset(OpAMD64TESTBconst)
v.AuxInt = int64(int8(c))
v.AddArg(x)
@ -7309,26 +7325,42 @@ func rewriteValueAMD64_OpAMD64CMPLconst(v *Value) bool {
v.reset(OpAMD64FlagLT_ULT)
return true
}
// match: (CMPLconst (ANDL x y) [0])
// match: (CMPLconst a:(ANDL x y) [0])
// cond: a.Uses == 1
// result: (TESTL x y)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDL {
break
}
y := a.Args[1]
x := a.Args[0]
if !(a.Uses == 1) {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
v.reset(OpAMD64TESTL)
v.AddArg2(x, y)
return true
}
// match: (CMPLconst (ANDLconst [c] x) [0])
// match: (CMPLconst a:(ANDLconst [c] x) [0])
// cond: a.Uses == 1
// result: (TESTLconst [c] x)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDLconst {
break
}
c := a.AuxInt
x := a.Args[0]
if !(a.Uses == 1) {
break
}
c := v_0.AuxInt
x := v_0.Args[0]
v.reset(OpAMD64TESTLconst)
v.AuxInt = c
v.AddArg(x)
@ -7874,26 +7906,42 @@ func rewriteValueAMD64_OpAMD64CMPQconst(v *Value) bool {
v.reset(OpAMD64FlagLT_ULT)
return true
}
// match: (CMPQconst (ANDQ x y) [0])
// match: (CMPQconst a:(ANDQ x y) [0])
// cond: a.Uses == 1
// result: (TESTQ x y)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDQ {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDQ {
break
}
y := a.Args[1]
x := a.Args[0]
if !(a.Uses == 1) {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
v.reset(OpAMD64TESTQ)
v.AddArg2(x, y)
return true
}
// match: (CMPQconst (ANDQconst [c] x) [0])
// match: (CMPQconst a:(ANDQconst [c] x) [0])
// cond: a.Uses == 1
// result: (TESTQconst [c] x)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDQconst {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDQconst {
break
}
c := a.AuxInt
x := a.Args[0]
if !(a.Uses == 1) {
break
}
c := v_0.AuxInt
x := v_0.Args[0]
v.reset(OpAMD64TESTQconst)
v.AuxInt = c
v.AddArg(x)
@ -8244,26 +8292,42 @@ func rewriteValueAMD64_OpAMD64CMPWconst(v *Value) bool {
v.reset(OpAMD64FlagLT_ULT)
return true
}
// match: (CMPWconst (ANDL x y) [0])
// match: (CMPWconst a:(ANDL x y) [0])
// cond: a.Uses == 1
// result: (TESTW x y)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDL {
break
}
y := a.Args[1]
x := a.Args[0]
if !(a.Uses == 1) {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
v.reset(OpAMD64TESTW)
v.AddArg2(x, y)
return true
}
// match: (CMPWconst (ANDLconst [c] x) [0])
// match: (CMPWconst a:(ANDLconst [c] x) [0])
// cond: a.Uses == 1
// result: (TESTWconst [int64(int16(c))] x)
for {
if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
if v.AuxInt != 0 {
break
}
a := v_0
if a.Op != OpAMD64ANDLconst {
break
}
c := a.AuxInt
x := a.Args[0]
if !(a.Uses == 1) {
break
}
c := v_0.AuxInt
x := v_0.Args[0]
v.reset(OpAMD64TESTWconst)
v.AuxInt = int64(int16(c))
v.AddArg(x)

24
test/codegen/logic.go Normal file
View file

@ -0,0 +1,24 @@
// asmcheck
// 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 codegen
var gx, gy int
// Test to make sure that (CMPQ (ANDQ x y) [0]) does not get rewritten to
// (TESTQ x y) if the ANDQ has other uses. If that rewrite happens, then one
// of the args of the ANDQ needs to be saved so it can be used as the arg to TESTQ.
func andWithUse(x, y int) int {
// Load x,y into registers, so those MOVQ will not appear at the z := x&y line.
gx, gy = x, y
// amd64:-"MOVQ"
z := x & y
if z == 0 {
return 77
}
// use z by returning it
return z
}