cmd/compile: duplicate instructions after rewrite func results #74788
Description
Go version
go version go1.26-devel_b10eb1d042 Mon Jul 28 17:39:26 2025 -0700 linux/amd64
Output of go env in your module/workspace:
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='0'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/kylin/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/kylin/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3413711938=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/home/kylin/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/kylin/go'
GOPRIVATE=''
GOPROXY='https://goproxy.cn,direct'
GOROOT='/home/kylin/go/src/googlesource.com/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/kylin/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/kylin/go/src/googlesource.com/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.26-devel_b10eb1d042 Mon Jul 28 17:39:26 2025 -0700'
GOWORK=''
PKG_CONFIG='pkg-config'What did you do?
Disassemble the following function:
//go:noinline
func fn(a [2]int) (r [2]int) {
return a
}What did you see happen?
0x4690e0 0f10442408 MOVUPS 0x8(SP), X0
0x4690e5 0f11442418 MOVUPS X0, 0x18(SP)
0x4690ea 0f10442408 MOVUPS 0x8(SP), X0
0x4690ef 0f11442418 MOVUPS X0, 0x18(SP)
0x4690f4 c3 RET
What did you expect to see?
0x4690e0 0f10442408 MOVUPS 0x8(SP), X0
0x4690e5 0f11442418 MOVUPS X0, 0x18(SP)
0x4690ea c3 RET