go/test/phiopt.go

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cmd/compile/internal/ssa: strengthen phiopt pass The current phiopt pass just transforms the following code x := false if b { x = true} into x = b But we find code in runtime.atoi like this: neg := false if s[0] == '-' { neg = true s = s[1:] } The current phiopt pass does not covert it into code like: neg := s[0] == '-' if neg { s = s[1:] } Therefore, this patch strengthens the phiopt pass so that the boolean Phi value "neg" can be replaced with a copy of control value "s[0] == '-'", thereby using "cmp+cset" instead of a branch. But in some cases even replacing the boolean Phis cannot eliminate this branch. In the following case, this patch replaces "d" with a copy of "a<0", but the regalloc pass will insert the "Load {c}" value into an empty block to split the live ranges, which causes the branch to not be eliminated. For example: func test(a, b, c int) (bool, int) { d := false if (a<0) { if (b<0) { c = c+1 } d = true } return d, c } The optimized assembly code: MOVD "".a(FP), R0 TBZ $63, R0, 48 MOVD "".c+16(FP), R1 ADD $1, R1, R2 MOVD "".b+8(FP), R3 CMP ZR, R3 CSEL LT, R2, R1, R1 CMP ZR, R0 CSET LT, R0 MOVB R0, "".~r3+24(FP) MOVD R1, "".~r4+32(FP) RET (R30) MOVD "".c+16(FP), R1 JMP 28 The benchmark: name old time/op new time/op delta pkg:cmd/compile/internal/ssa goos:linux goarch:arm64 PhioptPass 117783.250000ns +- 1% 117219.111111ns +- 1% ~ (p=0.074 n=8+9) Statistical data from compilecmp tool: compilecmp local/master -> HEAD local/master (a826f7dc45): debug/dwarf: support DW_FORM_rnglistx aka formRnglistx HEAD (e57e003c10): cmd/compile/internal/ssa: strengthen phiopt pass benchstat -geomean /tmp/2516644532 /tmp/1075915815 completed 50 of 50, estimated time remaining 0s (ETA 7:10PM) name old time/op new time/op delta Template 554ms _ 3% 553ms _ 3% ~ (p=0.986 n=49+48) Unicode 252ms _ 4% 249ms _ 4% -1.33% (p=0.002 n=47+49) GoTypes 3.16s _ 3% 3.18s _ 3% +0.77% (p=0.022 n=44+48) Compiler 257ms _ 4% 258ms _ 4% ~ (p=0.121 n=50+49) SSA 24.2s _ 4% 24.2s _ 5% ~ (p=0.694 n=49+50) Flate 338ms _ 4% 338ms _ 4% ~ (p=0.592 n=43+46) GoParser 506ms _ 3% 507ms _ 3% ~ (p=0.942 n=49+50) Reflect 1.37s _ 4% 1.37s _ 5% ~ (p=0.408 n=50+50) Tar 486ms _ 3% 487ms _ 4% ~ (p=0.911 n=47+50) XML 619ms _ 2% 619ms _ 3% ~ (p=0.368 n=46+48) LinkCompiler 1.29s _31% 1.32s _23% ~ (p=0.306 n=49+44) ExternalLinkCompiler 3.39s _10% 3.36s _ 6% ~ (p=0.311 n=48+46) LinkWithoutDebugCompiler 846ms _37% 793ms _24% -6.29% (p=0.040 n=50+49) [Geo mean] 974ms 971ms -0.36% name old user-time/op new user-time/op delta Template 910ms _12% 893ms _13% ~ (p=0.098 n=49+49) Unicode 495ms _28% 492ms _18% ~ (p=0.562 n=50+46) GoTypes 4.42s _15% 4.39s _13% ~ (p=0.684 n=49+50) Compiler 419ms _22% 422ms _16% ~ (p=0.579 n=48+50) SSA 36.5s _ 7% 36.6s _ 8% ~ (p=0.465 n=50+47) Flate 521ms _21% 523ms _16% ~ (p=0.889 n=50+47) GoParser 810ms _12% 792ms _15% ~ (p=0.149 n=50+50) Reflect 1.98s _13% 2.02s _13% ~ (p=0.144 n=47+50) Tar 826ms _15% 806ms _19% ~ (p=0.115 n=49+49) XML 988ms _14% 1003ms _14% ~ (p=0.179 n=50+50) LinkCompiler 1.79s _ 8% 1.84s _11% +2.81% (p=0.001 n=49+49) ExternalLinkCompiler 3.69s _ 4% 3.71s _ 3% ~ (p=0.261 n=50+50) LinkWithoutDebugCompiler 838ms _10% 827ms _11% ~ (p=0.323 n=50+48) [Geo mean] 1.44s 1.44s -0.05% name old alloc/op new alloc/op delta Template 39.0MB _ 1% 39.0MB _ 1% ~ (p=0.445 n=50+49) Unicode 28.5MB _ 0% 28.5MB _ 0% ~ (p=0.460 n=50+50) GoTypes 169MB _ 1% 169MB _ 1% ~ (p=0.092 n=48+50) Compiler 23.4MB _ 1% 23.4MB _ 1% -0.19% (p=0.032 n=50+49) SSA 1.54GB _ 0% 1.55GB _ 1% +0.14% (p=0.001 n=50+50) Flate 23.8MB _ 1% 23.8MB _ 2% ~ (p=0.702 n=49+49) GoParser 35.4MB _ 1% 35.4MB _ 1% ~ (p=0.786 n=50+50) Reflect 85.3MB _ 1% 85.3MB _ 1% ~ (p=0.298 n=50+50) Tar 34.6MB _ 2% 34.6MB _ 2% ~ (p=0.683 n=50+50) XML 44.5MB _ 3% 44.0MB _ 2% -1.05% (p=0.000 n=50+46) LinkCompiler 136MB _ 0% 136MB _ 0% +0.01% (p=0.005 n=50+50) ExternalLinkCompiler 128MB _ 0% 128MB _ 0% ~ (p=0.179 n=50+50) LinkWithoutDebugCompiler 84.3MB _ 0% 84.3MB _ 0% +0.01% (p=0.006 n=50+50) [Geo mean] 70.7MB 70.6MB -0.07% name old allocs/op new allocs/op delta Template 410k _ 0% 410k _ 0% ~ (p=0.606 n=48+49) Unicode 310k _ 0% 310k _ 0% ~ (p=0.674 n=50+50) GoTypes 1.81M _ 0% 1.81M _ 0% ~ (p=0.674 n=50+50) Compiler 202k _ 0% 202k _ 0% +0.02% (p=0.046 n=50+50) SSA 16.3M _ 0% 16.3M _ 0% +0.10% (p=0.000 n=50+50) Flate 244k _ 0% 244k _ 0% ~ (p=0.834 n=49+50) GoParser 380k _ 0% 380k _ 0% ~ (p=0.410 n=50+50) Reflect 1.08M _ 0% 1.08M _ 0% ~ (p=0.782 n=48+50) Tar 368k _ 0% 368k _ 0% ~ (p=0.585 n=50+49) XML 453k _ 0% 453k _ 0% -0.01% (p=0.025 n=49+49) LinkCompiler 713k _ 0% 713k _ 0% +0.01% (p=0.044 n=50+50) ExternalLinkCompiler 794k _ 0% 794k _ 0% +0.01% (p=0.000 n=50+49) LinkWithoutDebugCompiler 251k _ 0% 251k _ 0% ~ (p=0.092 n=47+50) [Geo mean] 615k 615k +0.01% name old maxRSS/op new maxRSS/op delta Template 37.0M _ 4% 37.2M _ 3% ~ (p=0.062 n=48+48) Unicode 36.9M _ 5% 37.3M _ 4% +1.10% (p=0.021 n=50+47) GoTypes 94.3M _ 3% 94.9M _ 4% +0.69% (p=0.022 n=45+46) Compiler 33.4M _ 3% 33.4M _ 5% ~ (p=0.964 n=49+50) SSA 741M _ 3% 738M _ 3% ~ (p=0.164 n=50+50) Flate 28.5M _ 6% 28.8M _ 4% +1.07% (p=0.009 n=50+49) GoParser 35.0M _ 3% 35.3M _ 4% +0.83% (p=0.010 n=50+48) Reflect 57.2M _ 6% 57.1M _ 4% ~ (p=0.815 n=50+49) Tar 34.9M _ 3% 35.0M _ 3% ~ (p=0.134 n=49+48) XML 39.5M _ 5% 40.0M _ 3% +1.35% (p=0.001 n=50+48) LinkCompiler 220M _ 2% 220M _ 2% ~ (p=0.547 n=49+48) ExternalLinkCompiler 235M _ 2% 236M _ 2% ~ (p=0.538 n=47+44) LinkWithoutDebugCompiler 179M _ 1% 179M _ 1% ~ (p=0.775 n=50+50) [Geo mean] 74.9M 75.2M +0.43% name old text-bytes new text-bytes delta HelloSize 784kB _ 0% 784kB _ 0% +0.01% (p=0.000 n=50+50) name old data-bytes new data-bytes delta HelloSize 13.1kB _ 0% 13.1kB _ 0% ~ (all equal) name old bss-bytes new bss-bytes delta HelloSize 206kB _ 0% 206kB _ 0% ~ (all equal) name old exe-bytes new exe-bytes delta HelloSize 1.28MB _ 0% 1.28MB _ 0% +0.00% (p=0.000 n=50+50) file before after _ % addr2line 4006300 4004484 -1816 -0.045% api 5029956 5029324 -632 -0.013% asm 4936311 4939423 +3112 +0.063% buildid 2595059 2595291 +232 +0.009% cgo 4401029 4397333 -3696 -0.084% compile 22246677 22246863 +186 +0.001% cover 4443825 4443065 -760 -0.017% dist 3366078 3365838 -240 -0.007% doc 3776391 3776615 +224 +0.006% fix 3218800 3218648 -152 -0.005% link 6365321 6365345 +24 +0.000% nm 3923625 3923857 +232 +0.006% objdump 4295569 4295041 -528 -0.012% pack 2390745 2389217 -1528 -0.064% pprof 12870094 12866942 -3152 -0.024% test2json 2587265 2587073 -192 -0.007% trace 9612629 9613981 +1352 +0.014% vet 6791008 6792072 +1064 +0.016% total 106856682 106850412 -6270 -0.006% Update #37608 Change-Id: Ic6206b22fd1faf570be9fd3c2511aa6c4ce38cdb Reviewed-on: https://go-review.googlesource.com/c/go/+/252937 Trust: fannie zhang <Fannie.Zhang@arm.com> Run-TryBot: fannie zhang <Fannie.Zhang@arm.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2020-07-28 02:29:06 +00:00
// +build amd64 s390x arm64
// errorcheck -0 -d=ssa/phiopt/debug=3
// Copyright 2016 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 main
//go:noinline
func f0(a bool) bool {
x := false
if a {
x = true
} else {
x = false
}
return x // ERROR "converted OpPhi to Copy$"
}
//go:noinline
func f1(a bool) bool {
x := false
if a {
x = false
} else {
x = true
}
return x // ERROR "converted OpPhi to Not$"
}
//go:noinline
func f2(a, b int) bool {
x := true
if a == b {
x = false
}
return x // ERROR "converted OpPhi to Not$"
}
//go:noinline
func f3(a, b int) bool {
x := false
if a == b {
x = true
}
return x // ERROR "converted OpPhi to Copy$"
}
//go:noinline
func f4(a, b bool) bool {
return a || b // ERROR "converted OpPhi to OrB$"
}
//go:noinline
func f5or(a int, b bool) bool {
var x bool
if a == 0 {
x = true
} else {
x = b
}
return x // ERROR "converted OpPhi to OrB$"
}
//go:noinline
func f5and(a int, b bool) bool {
var x bool
if a == 0 {
x = b
} else {
x = false
}
return x // ERROR "converted OpPhi to AndB$"
}
//go:noinline
func f6or(a int, b bool) bool {
x := b
if a == 0 {
// f6or has side effects so the OpPhi should not be converted.
x = f6or(a, b)
}
return x
}
//go:noinline
func f6and(a int, b bool) bool {
x := b
if a == 0 {
// f6and has side effects so the OpPhi should not be converted.
x = f6and(a, b)
}
return x
}
//go:noinline
func f7or(a bool, b bool) bool {
return a || b // ERROR "converted OpPhi to OrB$"
}
//go:noinline
func f7and(a bool, b bool) bool {
return a && b // ERROR "converted OpPhi to AndB$"
}
cmd/compile/internal/ssa: strengthen phiopt pass The current phiopt pass just transforms the following code x := false if b { x = true} into x = b But we find code in runtime.atoi like this: neg := false if s[0] == '-' { neg = true s = s[1:] } The current phiopt pass does not covert it into code like: neg := s[0] == '-' if neg { s = s[1:] } Therefore, this patch strengthens the phiopt pass so that the boolean Phi value "neg" can be replaced with a copy of control value "s[0] == '-'", thereby using "cmp+cset" instead of a branch. But in some cases even replacing the boolean Phis cannot eliminate this branch. In the following case, this patch replaces "d" with a copy of "a<0", but the regalloc pass will insert the "Load {c}" value into an empty block to split the live ranges, which causes the branch to not be eliminated. For example: func test(a, b, c int) (bool, int) { d := false if (a<0) { if (b<0) { c = c+1 } d = true } return d, c } The optimized assembly code: MOVD "".a(FP), R0 TBZ $63, R0, 48 MOVD "".c+16(FP), R1 ADD $1, R1, R2 MOVD "".b+8(FP), R3 CMP ZR, R3 CSEL LT, R2, R1, R1 CMP ZR, R0 CSET LT, R0 MOVB R0, "".~r3+24(FP) MOVD R1, "".~r4+32(FP) RET (R30) MOVD "".c+16(FP), R1 JMP 28 The benchmark: name old time/op new time/op delta pkg:cmd/compile/internal/ssa goos:linux goarch:arm64 PhioptPass 117783.250000ns +- 1% 117219.111111ns +- 1% ~ (p=0.074 n=8+9) Statistical data from compilecmp tool: compilecmp local/master -> HEAD local/master (a826f7dc45): debug/dwarf: support DW_FORM_rnglistx aka formRnglistx HEAD (e57e003c10): cmd/compile/internal/ssa: strengthen phiopt pass benchstat -geomean /tmp/2516644532 /tmp/1075915815 completed 50 of 50, estimated time remaining 0s (ETA 7:10PM) name old time/op new time/op delta Template 554ms _ 3% 553ms _ 3% ~ (p=0.986 n=49+48) Unicode 252ms _ 4% 249ms _ 4% -1.33% (p=0.002 n=47+49) GoTypes 3.16s _ 3% 3.18s _ 3% +0.77% (p=0.022 n=44+48) Compiler 257ms _ 4% 258ms _ 4% ~ (p=0.121 n=50+49) SSA 24.2s _ 4% 24.2s _ 5% ~ (p=0.694 n=49+50) Flate 338ms _ 4% 338ms _ 4% ~ (p=0.592 n=43+46) GoParser 506ms _ 3% 507ms _ 3% ~ (p=0.942 n=49+50) Reflect 1.37s _ 4% 1.37s _ 5% ~ (p=0.408 n=50+50) Tar 486ms _ 3% 487ms _ 4% ~ (p=0.911 n=47+50) XML 619ms _ 2% 619ms _ 3% ~ (p=0.368 n=46+48) LinkCompiler 1.29s _31% 1.32s _23% ~ (p=0.306 n=49+44) ExternalLinkCompiler 3.39s _10% 3.36s _ 6% ~ (p=0.311 n=48+46) LinkWithoutDebugCompiler 846ms _37% 793ms _24% -6.29% (p=0.040 n=50+49) [Geo mean] 974ms 971ms -0.36% name old user-time/op new user-time/op delta Template 910ms _12% 893ms _13% ~ (p=0.098 n=49+49) Unicode 495ms _28% 492ms _18% ~ (p=0.562 n=50+46) GoTypes 4.42s _15% 4.39s _13% ~ (p=0.684 n=49+50) Compiler 419ms _22% 422ms _16% ~ (p=0.579 n=48+50) SSA 36.5s _ 7% 36.6s _ 8% ~ (p=0.465 n=50+47) Flate 521ms _21% 523ms _16% ~ (p=0.889 n=50+47) GoParser 810ms _12% 792ms _15% ~ (p=0.149 n=50+50) Reflect 1.98s _13% 2.02s _13% ~ (p=0.144 n=47+50) Tar 826ms _15% 806ms _19% ~ (p=0.115 n=49+49) XML 988ms _14% 1003ms _14% ~ (p=0.179 n=50+50) LinkCompiler 1.79s _ 8% 1.84s _11% +2.81% (p=0.001 n=49+49) ExternalLinkCompiler 3.69s _ 4% 3.71s _ 3% ~ (p=0.261 n=50+50) LinkWithoutDebugCompiler 838ms _10% 827ms _11% ~ (p=0.323 n=50+48) [Geo mean] 1.44s 1.44s -0.05% name old alloc/op new alloc/op delta Template 39.0MB _ 1% 39.0MB _ 1% ~ (p=0.445 n=50+49) Unicode 28.5MB _ 0% 28.5MB _ 0% ~ (p=0.460 n=50+50) GoTypes 169MB _ 1% 169MB _ 1% ~ (p=0.092 n=48+50) Compiler 23.4MB _ 1% 23.4MB _ 1% -0.19% (p=0.032 n=50+49) SSA 1.54GB _ 0% 1.55GB _ 1% +0.14% (p=0.001 n=50+50) Flate 23.8MB _ 1% 23.8MB _ 2% ~ (p=0.702 n=49+49) GoParser 35.4MB _ 1% 35.4MB _ 1% ~ (p=0.786 n=50+50) Reflect 85.3MB _ 1% 85.3MB _ 1% ~ (p=0.298 n=50+50) Tar 34.6MB _ 2% 34.6MB _ 2% ~ (p=0.683 n=50+50) XML 44.5MB _ 3% 44.0MB _ 2% -1.05% (p=0.000 n=50+46) LinkCompiler 136MB _ 0% 136MB _ 0% +0.01% (p=0.005 n=50+50) ExternalLinkCompiler 128MB _ 0% 128MB _ 0% ~ (p=0.179 n=50+50) LinkWithoutDebugCompiler 84.3MB _ 0% 84.3MB _ 0% +0.01% (p=0.006 n=50+50) [Geo mean] 70.7MB 70.6MB -0.07% name old allocs/op new allocs/op delta Template 410k _ 0% 410k _ 0% ~ (p=0.606 n=48+49) Unicode 310k _ 0% 310k _ 0% ~ (p=0.674 n=50+50) GoTypes 1.81M _ 0% 1.81M _ 0% ~ (p=0.674 n=50+50) Compiler 202k _ 0% 202k _ 0% +0.02% (p=0.046 n=50+50) SSA 16.3M _ 0% 16.3M _ 0% +0.10% (p=0.000 n=50+50) Flate 244k _ 0% 244k _ 0% ~ (p=0.834 n=49+50) GoParser 380k _ 0% 380k _ 0% ~ (p=0.410 n=50+50) Reflect 1.08M _ 0% 1.08M _ 0% ~ (p=0.782 n=48+50) Tar 368k _ 0% 368k _ 0% ~ (p=0.585 n=50+49) XML 453k _ 0% 453k _ 0% -0.01% (p=0.025 n=49+49) LinkCompiler 713k _ 0% 713k _ 0% +0.01% (p=0.044 n=50+50) ExternalLinkCompiler 794k _ 0% 794k _ 0% +0.01% (p=0.000 n=50+49) LinkWithoutDebugCompiler 251k _ 0% 251k _ 0% ~ (p=0.092 n=47+50) [Geo mean] 615k 615k +0.01% name old maxRSS/op new maxRSS/op delta Template 37.0M _ 4% 37.2M _ 3% ~ (p=0.062 n=48+48) Unicode 36.9M _ 5% 37.3M _ 4% +1.10% (p=0.021 n=50+47) GoTypes 94.3M _ 3% 94.9M _ 4% +0.69% (p=0.022 n=45+46) Compiler 33.4M _ 3% 33.4M _ 5% ~ (p=0.964 n=49+50) SSA 741M _ 3% 738M _ 3% ~ (p=0.164 n=50+50) Flate 28.5M _ 6% 28.8M _ 4% +1.07% (p=0.009 n=50+49) GoParser 35.0M _ 3% 35.3M _ 4% +0.83% (p=0.010 n=50+48) Reflect 57.2M _ 6% 57.1M _ 4% ~ (p=0.815 n=50+49) Tar 34.9M _ 3% 35.0M _ 3% ~ (p=0.134 n=49+48) XML 39.5M _ 5% 40.0M _ 3% +1.35% (p=0.001 n=50+48) LinkCompiler 220M _ 2% 220M _ 2% ~ (p=0.547 n=49+48) ExternalLinkCompiler 235M _ 2% 236M _ 2% ~ (p=0.538 n=47+44) LinkWithoutDebugCompiler 179M _ 1% 179M _ 1% ~ (p=0.775 n=50+50) [Geo mean] 74.9M 75.2M +0.43% name old text-bytes new text-bytes delta HelloSize 784kB _ 0% 784kB _ 0% +0.01% (p=0.000 n=50+50) name old data-bytes new data-bytes delta HelloSize 13.1kB _ 0% 13.1kB _ 0% ~ (all equal) name old bss-bytes new bss-bytes delta HelloSize 206kB _ 0% 206kB _ 0% ~ (all equal) name old exe-bytes new exe-bytes delta HelloSize 1.28MB _ 0% 1.28MB _ 0% +0.00% (p=0.000 n=50+50) file before after _ % addr2line 4006300 4004484 -1816 -0.045% api 5029956 5029324 -632 -0.013% asm 4936311 4939423 +3112 +0.063% buildid 2595059 2595291 +232 +0.009% cgo 4401029 4397333 -3696 -0.084% compile 22246677 22246863 +186 +0.001% cover 4443825 4443065 -760 -0.017% dist 3366078 3365838 -240 -0.007% doc 3776391 3776615 +224 +0.006% fix 3218800 3218648 -152 -0.005% link 6365321 6365345 +24 +0.000% nm 3923625 3923857 +232 +0.006% objdump 4295569 4295041 -528 -0.012% pack 2390745 2389217 -1528 -0.064% pprof 12870094 12866942 -3152 -0.024% test2json 2587265 2587073 -192 -0.007% trace 9612629 9613981 +1352 +0.014% vet 6791008 6792072 +1064 +0.016% total 106856682 106850412 -6270 -0.006% Update #37608 Change-Id: Ic6206b22fd1faf570be9fd3c2511aa6c4ce38cdb Reviewed-on: https://go-review.googlesource.com/c/go/+/252937 Trust: fannie zhang <Fannie.Zhang@arm.com> Run-TryBot: fannie zhang <Fannie.Zhang@arm.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2020-07-28 02:29:06 +00:00
//go:noinline
func f8(s string) (string, bool) {
neg := false
if s[0] == '-' { // ERROR "converted OpPhi to Copy$"
neg = true
s = s[1:]
}
return s, neg
}
var d int
//go:noinline
func f9(a, b int) bool {
c := false
if a < 0 { // ERROR "converted OpPhi to Copy$"
if b < 0 {
d = d + 1
}
c = true
}
return c
}
func main() {
}