cmd/compile: optimize regalloc for phi value
When allocating registers for phi value, only the primary predecessor is considered.
Taking into account the allocation status of other predecessors can help reduce
unnecessary copy or spill operations. Many such cases can be found in the standard
library, such as runtime.wirep, moveByType, etc. The test results from benchstat
also show that this change helps reduce the file size.
name old time/op new time/op delta
Template 328ms ± 5% 326ms ± 4% ~ (p=0.254 n=50+47)
Unicode 156ms ± 7% 158ms ±10% ~ (p=0.412 n=49+49)
GoTypes 1.07s ± 3% 1.07s ± 2% ~ (p=0.664 n=48+49)
Compiler 4.43s ± 3% 4.44s ± 3% ~ (p=0.758 n=48+50)
SSA 10.3s ± 2% 10.4s ± 2% +0.43% (p=0.017 n=50+46)
Flate 208ms ± 9% 209ms ± 7% ~ (p=0.920 n=49+46)
GoParser 260ms ± 5% 262ms ± 4% ~ (p=0.063 n=50+48)
Reflect 687ms ± 3% 685ms ± 2% ~ (p=0.459 n=50+48)
Tar 293ms ± 4% 293ms ± 5% ~ (p=0.695 n=49+48)
XML 391ms ± 4% 389ms ± 3% ~ (p=0.109 n=49+46)
LinkCompiler 570ms ± 5% 563ms ± 5% -1.10% (p=0.006 n=46+47)
ExternalLinkCompiler 1.57s ± 3% 1.56s ± 3% ~ (p=0.118 n=47+46)
LinkWithoutDebugCompiler 349ms ± 6% 349ms ± 5% ~ (p=0.726 n=49+47)
[Geo mean] 645ms 645ms -0.05%
name old user-time/op new user-time/op delta
Template 507ms ±14% 513ms ±14% ~ (p=0.398 n=48+49)
Unicode 345ms ±29% 345ms ±38% ~ (p=0.521 n=47+49)
GoTypes 1.95s ±16% 1.94s ±19% ~ (p=0.324 n=50+50)
Compiler 8.26s ±16% 8.22s ±14% ~ (p=0.834 n=50+50)
SSA 19.6s ± 8% 19.2s ±15% ~ (p=0.056 n=50+50)
Flate 293ms ± 9% 299ms ±12% ~ (p=0.057 n=47+50)
GoParser 388ms ± 9% 387ms ±14% ~ (p=0.660 n=46+50)
Reflect 1.15s ±28% 1.12s ±18% ~ (p=0.648 n=49+48)
Tar 456ms ±10% 476ms ±15% +4.48% (p=0.001 n=46+48)
XML 648ms ±27% 634ms ±16% ~ (p=0.685 n=50+46)
LinkCompiler 1.00s ± 8% 1.00s ± 8% ~ (p=0.638 n=50+50)
ExternalLinkCompiler 1.96s ± 5% 1.96s ± 5% ~ (p=0.792 n=50+50)
LinkWithoutDebugCompiler 443ms ±10% 442ms ±11% ~ (p=0.813 n=50+50)
[Geo mean] 1.05s 1.05s -0.09%
name old alloc/op new alloc/op delta
Template 36.0MB ± 0% 36.0MB ± 0% ~ (p=0.599 n=49+50)
Unicode 29.8MB ± 0% 29.8MB ± 0% ~ (p=0.739 n=50+50)
GoTypes 118MB ± 0% 118MB ± 0% ~ (p=0.436 n=50+50)
Compiler 562MB ± 0% 562MB ± 0% ~ (p=0.693 n=50+50)
SSA 1.42GB ± 0% 1.42GB ± 0% -0.10% (p=0.000 n=50+49)
Flate 22.5MB ± 0% 22.5MB ± 0% ~ (p=0.429 n=48+49)
GoParser 27.7MB ± 0% 27.7MB ± 0% ~ (p=0.705 n=49+48)
Reflect 77.7MB ± 0% 77.7MB ± 0% -0.01% (p=0.043 n=50+50)
Tar 33.8MB ± 0% 33.8MB ± 0% ~ (p=0.241 n=49+50)
XML 42.8MB ± 0% 42.8MB ± 0% ~ (p=0.677 n=47+49)
LinkCompiler 98.3MB ± 0% 98.3MB ± 0% ~ (p=0.157 n=50+50)
ExternalLinkCompiler 89.4MB ± 0% 89.4MB ± 0% ~ (p=0.683 n=50+50)
LinkWithoutDebugCompiler 56.7MB ± 0% 56.7MB ± 0% ~ (p=0.155 n=49+49)
[Geo mean] 77.3MB 77.3MB -0.01%
name old allocs/op new allocs/op delta
Template 367k ± 0% 367k ± 0% ~ (p=0.863 n=50+50)
Unicode 345k ± 0% 345k ± 0% ~ (p=0.744 n=49+49)
GoTypes 1.28M ± 0% 1.28M ± 0% ~ (p=0.957 n=48+50)
Compiler 5.39M ± 0% 5.39M ± 0% +0.00% (p=0.012 n=50+49)
SSA 13.9M ± 0% 13.9M ± 0% +0.02% (p=0.000 n=47+49)
Flate 230k ± 0% 230k ± 0% -0.01% (p=0.007 n=47+49)
GoParser 292k ± 0% 292k ± 0% ~ (p=0.891 n=50+49)
Reflect 977k ± 0% 977k ± 0% ~ (p=0.274 n=50+50)
Tar 343k ± 0% 343k ± 0% ~ (p=0.942 n=50+50)
XML 418k ± 0% 418k ± 0% ~ (p=0.374 n=50+49)
LinkCompiler 516k ± 0% 516k ± 0% ~ (p=0.205 n=49+47)
ExternalLinkCompiler 570k ± 0% 570k ± 0% ~ (p=0.783 n=49+47)
LinkWithoutDebugCompiler 169k ± 0% 169k ± 0% ~ (p=0.233 n=50+46)
[Geo mean] 672k 672k +0.00%
name old maxRSS/op new maxRSS/op delta
Template 34.5M ± 3% 34.4M ± 3% ~ (p=0.566 n=49+48)
Unicode 36.0M ± 6% 35.9M ± 6% ~ (p=0.736 n=50+50)
GoTypes 75.7M ± 7% 75.4M ± 5% ~ (p=0.412 n=50+50)
Compiler 314M ±10% 313M ± 8% ~ (p=0.708 n=50+50)
SSA 730M ± 6% 735M ± 6% ~ (p=0.324 n=50+50)
Flate 25.8M ± 5% 25.6M ± 6% ~ (p=0.415 n=49+50)
GoParser 28.5M ± 3% 28.5M ± 4% ~ (p=0.977 n=46+50)
Reflect 57.4M ± 4% 57.2M ± 3% ~ (p=0.173 n=50+50)
Tar 33.3M ± 3% 33.2M ± 4% ~ (p=0.621 n=48+50)
XML 39.6M ± 5% 39.6M ± 4% ~ (p=0.997 n=50+50)
LinkCompiler 168M ± 2% 167M ± 1% ~ (p=0.072 n=49+45)
ExternalLinkCompiler 179M ± 1% 179M ± 1% ~ (p=0.147 n=48+50)
LinkWithoutDebugCompiler 136M ± 1% 136M ± 1% ~ (p=0.789 n=47+49)
[Geo mean] 79.2M 79.1M -0.12%
name old text-bytes new text-bytes delta
HelloSize 812kB ± 0% 811kB ± 0% -0.06% (p=0.000 n=50+50)
name old data-bytes new data-bytes delta
HelloSize 13.3kB ± 0% 13.3kB ± 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 1.21MB ± 0% 1.21MB ± 0% -0.03% (p=0.000 n=50+50)
file before after Δ %
addr2line
4057421 4056237 -1184 -0.029%
api
4952451 4946715 -5736 -0.116%
asm
4888993 4888185 -808 -0.017%
buildid
2617705 2616441 -1264 -0.048%
cgo
4521849 4520681 -1168 -0.026%
compile
19143451 19141243 -2208 -0.012%
cover
4847391 4837151 -10240 -0.211%
dist
3473877 3472565 -1312 -0.038%
doc
3821496 3820432 -1064 -0.028%
fix
3220587 3220659 +72 +0.002%
link
6587504 6582576 -4928 -0.075%
nm
4000154 3998690 -1464 -0.037%
objdump
4409449 4407625 -1824 -0.041%
pack
2398086 2393110 -4976 -0.207%
pprof
13599060 13606111 +7051 +0.052%
test2json
2645148 2645692 +544 +0.021%
trace
10355281 10355862 +581 +0.006%
vet
6780026 6779666 -360 -0.005%
total
106319929 106289641 -30288 -0.028%
Change-Id: Ia5399286958c187c8664c769bbddf7bc4c1cae99
Reviewed-on: https://go-review.googlesource.com/c/go/+/263600
Run-TryBot: eric fang <eric.fang@arm.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: eric fang <eric.fang@arm.com>
Reviewed-by: Keith Randall <khr@golang.org>