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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>
133 lines
2 KiB
Go
133 lines
2 KiB
Go
// +build amd64 s390x arm64
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// errorcheck -0 -d=ssa/phiopt/debug=3
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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//go:noinline
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func f0(a bool) bool {
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x := false
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if a {
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x = true
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} else {
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x = false
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}
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return x // ERROR "converted OpPhi to Copy$"
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}
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//go:noinline
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func f1(a bool) bool {
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x := false
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if a {
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x = false
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} else {
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x = true
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}
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return x // ERROR "converted OpPhi to Not$"
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}
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//go:noinline
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func f2(a, b int) bool {
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x := true
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if a == b {
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x = false
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}
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return x // ERROR "converted OpPhi to Not$"
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}
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//go:noinline
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func f3(a, b int) bool {
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x := false
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if a == b {
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x = true
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}
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return x // ERROR "converted OpPhi to Copy$"
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}
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//go:noinline
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func f4(a, b bool) bool {
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return a || b // ERROR "converted OpPhi to OrB$"
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}
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//go:noinline
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func f5or(a int, b bool) bool {
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var x bool
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if a == 0 {
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x = true
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} else {
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x = b
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}
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return x // ERROR "converted OpPhi to OrB$"
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}
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//go:noinline
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func f5and(a int, b bool) bool {
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var x bool
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if a == 0 {
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x = b
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} else {
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x = false
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}
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return x // ERROR "converted OpPhi to AndB$"
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}
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//go:noinline
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func f6or(a int, b bool) bool {
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x := b
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if a == 0 {
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// f6or has side effects so the OpPhi should not be converted.
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x = f6or(a, b)
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}
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return x
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}
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//go:noinline
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func f6and(a int, b bool) bool {
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x := b
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if a == 0 {
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// f6and has side effects so the OpPhi should not be converted.
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x = f6and(a, b)
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}
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return x
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}
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//go:noinline
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func f7or(a bool, b bool) bool {
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return a || b // ERROR "converted OpPhi to OrB$"
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}
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//go:noinline
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func f7and(a bool, b bool) bool {
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return a && b // ERROR "converted OpPhi to AndB$"
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}
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//go:noinline
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func f8(s string) (string, bool) {
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neg := false
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if s[0] == '-' { // ERROR "converted OpPhi to Copy$"
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neg = true
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s = s[1:]
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}
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return s, neg
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}
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var d int
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//go:noinline
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func f9(a, b int) bool {
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c := false
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if a < 0 { // ERROR "converted OpPhi to Copy$"
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if b < 0 {
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d = d + 1
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}
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c = true
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}
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return c
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}
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func main() {
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}
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