cmd/asm: generates invalid MULX instruction

[armfazh]

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

$ go version
go version go1.20.1 linux/amd64

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="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOENV="/home/user/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/user/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/user/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"

CGO_ENABLED="1"

GOMOD=""

GOWORK=""

CGO_CFLAGS="-O2 -g"

CGO_CPPFLAGS=""

CGO_CXXFLAGS="-O2 -g"

CGO_FFLAGS="-O2 -g"

CGO_LDFLAGS="-O2 -g"

PKG_CONFIG="pkg-config"

GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1448370878=/tmp/go-build -gno-record-gcc-switches"

What did you do?

main.go

package main

var myGlobal = [2]uint64{0,0}

//go:noescape
func a1()

func main() {
    _ = myGlobal
    a1()
}

mulx_amd64.s

TEXT ·a1(SB),0,$0-0
    MULXQ ·myGlobal(SB), AX, CX
    RET

Command:

$ go mod init example.com/mulx
$ go build -buildmode=plugin

What did you expect to see?

Command compiles this program succesfully.

What did you see instead?

# example.com/mulx
asm: "".a1: invalid instruction: 00007 (/home/user/mulx_amd64.s:2)	MULXQ	(R15), CX
asm: assembly failed

[thanm]

@golang/compiler

[gopherbot]

Change https://go.dev/cl/471675 mentions this issue: cmd/asm: preserve 3rd arg when GOT-rewriting assembly instructions