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fanzha02 ba6bd967d2 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>		2021-03-29 05:50:11 +00:00
.github	.github: add link to questions in ISSUE_TEMPLATE	2020-01-06 17:05:31 +00:00
api	syscall: restore broken GetQueuedCompletionStatus signature but make it not crash	2021-02-24 23:35:00 +00:00
doc	cmd/go: assume Go 1.16 instead of Go 1.11 for dependencies that lack explicit 'go' directives	2021-03-19 19:59:56 +00:00
lib/time	lib/time, time/tzdata: update tzdata to 2021a	2021-01-25 16:08:46 +00:00
misc	cmd/compile, cmd/link: dynamically export writable static tmps	2021-03-16 23:14:54 +00:00
src	cmd/compile/internal/ssa: strengthen phiopt pass	2021-03-29 05:50:11 +00:00
test	cmd/compile/internal/ssa: strengthen phiopt pass	2021-03-29 05:50:11 +00:00
.gitattributes	all: treat all files as binary, but check in .bat with CRLF	2020-06-08 15:31:43 +00:00
.gitignore	.gitignore: ignore src/cmd/dist/dist	2017-10-28 21:55:49 +00:00
AUTHORS	A+C: add new e-mail addresses for Andy Pan	2021-03-12 02:56:04 +00:00
CONTRIBUTING.md	all: restore changes from faulty merge/revert	2018-02-12 20:13:59 +00:00
CONTRIBUTORS	A+C: add new e-mail addresses for Andy Pan	2021-03-12 02:56:04 +00:00
LICENSE	doc: revert copyright date to 2009	2016-06-01 22:40:04 +00:00
PATENTS	…
README.md	README: pull gopher image from website	2021-02-16 18:25:10 +00:00
SECURITY.md	SECURITY.md: update go versions	2019-09-26 15:34:57 +00:00
codereview.cfg	codereview.cfg: add codereview.cfg for master branch	2021-02-19 18:44:53 +00:00

README.md

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image by Renee French, licensed under Creative Commons 3.0 Attributions license.

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