зеркало из https://github.com/CryptoPro/go.git
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>
This commit is contained in:
fanzha02
fannie zhang
Родитель
23ffb5b9ae
Коммит
ba6bd967d2
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|
@ -0,0 +1,32 @@
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// Copyright 2020 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 ssa
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import (
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"math/rand"
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"testing"
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)
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var d int
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//go:noinline
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func fn(a, b int) bool {
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c := false
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if a > 0 {
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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 BenchmarkPhioptPass(b *testing.B) {
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for i := 0; i < b.N; i++ {
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a := rand.Perm(i/10 + 10)
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for i := 1; i < len(a)/2; i++ {
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fn(a[i]-a[i-1], a[i+len(a)/2-2]-a[i+len(a)/2-1])
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}
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}
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}
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@ -46,7 +46,6 @@ func phiopt(f *Func) {
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continue
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}
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// b0 is the if block giving the boolean value.
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// reverse is the predecessor from which the truth value comes.
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var reverse int
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if b0.Succs[0].b == pb0 && b0.Succs[1].b == pb1 {
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@ -120,6 +119,141 @@ func phiopt(f *Func) {
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}
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}
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}
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// strengthen phi optimization.
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// Main use case is to transform:
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// x := false
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// if c {
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// x = true
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// ...
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// }
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// into
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// x := c
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// if x { ... }
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//
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// For example, in SSA code a case appears as
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// b0
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// If c -> b, sb0
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// sb0
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// If d -> sd0, sd1
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// sd1
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// ...
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// sd0
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// Plain -> b
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// b
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// x = (OpPhi (ConstBool [true]) (ConstBool [false]))
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//
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// In this case we can also replace x with a copy of c.
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//
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// The optimization idea:
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// 1. block b has a phi value x, x = OpPhi (ConstBool [true]) (ConstBool [false]),
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// and len(b.Preds) is equal to 2.
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// 2. find the common dominator(b0) of the predecessors(pb0, pb1) of block b, and the
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// dominator(b0) is a If block.
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// Special case: one of the predecessors(pb0 or pb1) is the dominator(b0).
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// 3. the successors(sb0, sb1) of the dominator need to dominate the predecessors(pb0, pb1)
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// of block b respectively.
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// 4. replace this boolean Phi based on dominator block.
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//
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// b0(pb0) b0(pb1) b0
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// | \ / | / \
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// | sb1 sb0 | sb0 sb1
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// | ... ... | ... ...
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// | pb1 pb0 | pb0 pb1
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// | / \ | \ /
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// b b b
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//
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var lca *lcaRange
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for _, b := range f.Blocks {
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if len(b.Preds) != 2 || len(b.Values) == 0 {
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// TODO: handle more than 2 predecessors, e.g. a || b || c.
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continue
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}
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for _, v := range b.Values {
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// find a phi value v = OpPhi (ConstBool [true]) (ConstBool [false]).
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// TODO: v = OpPhi (ConstBool [true]) (Arg <bool> {value})
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if v.Op != OpPhi {
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continue
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}
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if v.Args[0].Op != OpConstBool || v.Args[1].Op != OpConstBool {
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continue
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}
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if v.Args[0].AuxInt == v.Args[1].AuxInt {
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continue
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}
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pb0 := b.Preds[0].b
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pb1 := b.Preds[1].b
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if pb0.Kind == BlockIf && pb0 == sdom.Parent(b) {
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// special case: pb0 is the dominator block b0.
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// b0(pb0)
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// | \
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// | sb1
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// | ...
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// | pb1
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// | /
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// b
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// if another successor sb1 of b0(pb0) dominates pb1, do replace.
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ei := b.Preds[0].i
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sb1 := pb0.Succs[1-ei].b
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if sdom.IsAncestorEq(sb1, pb1) {
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convertPhi(pb0, v, ei)
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break
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}
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} else if pb1.Kind == BlockIf && pb1 == sdom.Parent(b) {
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// special case: pb1 is the dominator block b0.
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// b0(pb1)
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// / |
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// sb0 |
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// ... |
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// pb0 |
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// \ |
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// b
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// if another successor sb0 of b0(pb0) dominates pb0, do replace.
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ei := b.Preds[1].i
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sb0 := pb1.Succs[1-ei].b
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if sdom.IsAncestorEq(sb0, pb0) {
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convertPhi(pb1, v, ei-1)
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break
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}
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} else {
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// b0
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// / \
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// sb0 sb1
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// ... ...
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// pb0 pb1
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// \ /
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// b
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//
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// Build data structure for fast least-common-ancestor queries.
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if lca == nil {
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lca = makeLCArange(f)
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}
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b0 := lca.find(pb0, pb1)
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if b0.Kind != BlockIf {
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break
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}
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sb0 := b0.Succs[0].b
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sb1 := b0.Succs[1].b
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var reverse int
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if sdom.IsAncestorEq(sb0, pb0) && sdom.IsAncestorEq(sb1, pb1) {
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reverse = 0
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} else if sdom.IsAncestorEq(sb1, pb0) && sdom.IsAncestorEq(sb0, pb1) {
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reverse = 1
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} else {
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break
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}
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if len(sb0.Preds) != 1 || len(sb1.Preds) != 1 {
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// we can not replace phi value x in the following case.
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// if gp == nil || sp < lo { x = true}
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// if a || b { x = true }
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// so the if statement can only have one condition.
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break
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}
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convertPhi(b0, v, reverse)
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}
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}
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}
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}
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func phioptint(v *Value, b0 *Block, reverse int) {
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@ -174,3 +308,16 @@ func phioptint(v *Value, b0 *Block, reverse int) {
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f.Warnl(v.Block.Pos, "converted OpPhi bool -> int%d", v.Type.Size()*8)
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}
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}
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// b is the If block giving the boolean value.
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// v is the phi value v = (OpPhi (ConstBool [true]) (ConstBool [false])).
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// reverse is the predecessor from which the truth value comes.
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func convertPhi(b *Block, v *Value, reverse int) {
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f := b.Func
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ops := [2]Op{OpNot, OpCopy}
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v.reset(ops[v.Args[reverse].AuxInt])
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v.AddArg(b.Controls[0])
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if f.pass.debug > 0 {
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f.Warnl(b.Pos, "converted OpPhi to %v", v.Op)
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}
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}
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@ -178,6 +178,12 @@ func (t SparseTree) Child(x *Block) *Block {
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return t[x.ID].child
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}
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// Parent returns the parent of x in the dominator tree, or
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// nil if x is the function's entry.
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func (t SparseTree) Parent(x *Block) *Block {
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return t[x.ID].parent
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}
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// isAncestorEq reports whether x is an ancestor of or equal to y.
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func (t SparseTree) IsAncestorEq(x, y *Block) bool {
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if x == y {
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|
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@ -1,4 +1,4 @@
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// +build amd64 s390x
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// +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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@ -104,5 +104,29 @@ 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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