x/text: building as a plugin failure on darwin/arm64

[zoncoen]

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

$ go version
go version go1.20.1 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=""
GOCACHE="/Users/zoncoen/Library/Caches/go-build"
GOENV="/Users/zoncoen/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/zoncoen/dev/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/zoncoen/dev"
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="go1.20.1"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/zoncoen/dev/src/github.com/zoncoen-sample/go1.20-plugin-issue/go.mod"
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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/7b/75304vxx7szc4b0lph6y311c0000gp/T/go-build328686675=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

go build fails with -buildmode=plugin flag on darwin/arm64 if the code imports golang.org/x/text.

$ go build -buildmode=plugin -o plugin.so .

$ cat main.go
package main

import "golang.org/x/text/date"

func EtcUTC() int {
        return date.EtcUTC
}

The complete reproducing code is here.

What did you expect to see?

go build succeeds without error.

What did you see instead?

$ go build -buildmode=plugin -o plugin.so .
# golang.org/x/text/internal/language
:1: REGTMP used in large offset load: 00204 (/Users/zoncoen/dev/pkg/mod/golang.org/x/text@v0.7.0/internal/language/coverage.go:18)       MOVD    2189(R27), R5

I have confirmed that it builds correctly on linux/amd64.

[dmitshur]

CC @mpvl, @golang/runtime.

[cherrymui]

This looks like some issue in the assembler. I can look into that.

[dtrudg]

We are seeing the same issue on linux/arm64 (RHEL8, RHEL9, SLES15) when building a plugin with go 1.20.1

# golang.org/x/text/internal/language
    <autogenerated>:1: REGTMP used in large offset load: 00204 (golang.org/x/text@v0.7.0/internal/language/coverage.go:18)  MOVD    2189(R27), R5
    FATAL:   Plugin compile failed with error: while building plugin .so: exit status 1
    error: Bad exit status from /var/tmp/rpm-tmp.CfiMwQ (%build)
        Bad exit status from /var/tmp/rpm-tmp.CfiMwQ (%build)

The build completes without errors on linux/amd64, and on arm64 with go 1.19.5

[cherrymui]

I think this is due to CL https://golang.org/cl/445535 . The CL description says

If off is very large, it becomes:
  MOVD sym@GOT, REGTMP
  MOVD $off, Rt
  ADD  Rt, REGTMP
  MOVx (REGTMP), Ry

The question is what is Rt? It cannot use REGTMP. Maybe it can use Ry but currently it doesn't do so. Also, Ry only works for load, not store.

cc @golang/arm @erifan

[gopherbot]

Change https://go.dev/cl/474175 mentions this issue: Revert "cmd/compile: enable address folding for global symbols of shared library"

[cherrymui]

@gopherbot please backport this to Go 1.20. This can cause code failing to build. Thanks.

[gopherbot]

Backport issue(s) opened: #58920 (for 1.20).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/474235 mentions this issue: [release-branch.go1.20] Revert "cmd/compile: enable address folding for global symbols of shared library"

[gopherbot]

Change https://go.dev/cl/473999 mentions this issue: cmd/compile: enable address folding for globals on ARM64, just not -dynlink mode

[cherrymui]

The culprit CL is reverted. I sent CL 473999 to re-enable the optimization but not in -dynlink mode, which is -buildmode=plugin uses and where the problem actually is.

[zoncoen]

I confirmed gotip (devel go1.21-fc45eb3 Thu Mar 9 00:51:36 2023 +0000 darwin/arm64) could build actual code. Thank you.

[erifan]

I'm sorry to introduce this bug, and thanks @cherrymui for taking care of this.