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cmd/compile: combine xor and rotate right into shifted EOR on arm64 #48002

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ericlagergren opened this issue Aug 27, 2021 · 3 comments
Closed

cmd/compile: combine xor and rotate right into shifted EOR on arm64 #48002

ericlagergren opened this issue Aug 27, 2021 · 3 comments
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arch-arm64 FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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Backlog

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@ericlagergren
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ericlagergren commented Aug 27, 2021 •
edited

What version of Go are you using (go version)?

$ go version
go version go1.17 darwin/arm64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN="/Users/eric/gopath/bin"
GOCACHE="/Users/eric/Library/Caches/go-build"
GOENV="/Users/eric/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/eric/gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/eric/gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.17"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/2f/2_yz21b92h94_pvr2m00gzh80000gn/T/go-build15658485=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

https://play.golang.org/p/LNnAPEjrB1u

What did you expect to see?

The compiler generate EOR with a shifted register. E.g., turning

s.x3 = t3 ^ rotr(t3, 10) ^ rotr(t3, 17)

into (ignoring any typoed register names)

eor x3, x3, x2, ror #10
eor x2, x3, x2 ror #17

What did you see instead?

mov	x3, #10
ror	x3, x2, x3
eor	x3, x3, x2
mov	x4, #17
ror	x2, x2, x4
eor	x2, x2, x3
@ericlagergren ericlagergren changed the title cmd/compile: combine xor and rotate right on ARMv8 cmd/compile: combine xor and rotate right into shifted EOR on ARMv8 Aug 27, 2021
@toothrot toothrot added NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. arch-arm Issues solely affecting the 32-bit arm architecture. labels Aug 27, 2021
@toothrot toothrot added this to the Backlog milestone Aug 27, 2021
@RuinanSun
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I will work with my teammates on this issue, thanks for reporting that.

@greatroar greatroar mentioned this issue Sep 19, 2021
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@greatroar
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This is labeled arch-arm, but it's about arm64.

@ALTree ALTree added arch-arm64 and removed arch-arm Issues solely affecting the 32-bit arm architecture. labels Sep 19, 2021
@randall77 randall77 changed the title cmd/compile: combine xor and rotate right into shifted EOR on ARMv8 cmd/compile: combine xor and rotate right into shifted EOR on arm64 Sep 19, 2021
@gopherbot
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Change https://golang.org/cl/350912 mentions this issue: cmd/compile: allow rotates to be merged with arithmetic ops on arm64

@golang golang locked and limited conversation to collaborators Sep 20, 2022
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