cmd/compile: internal compiler error: panic: interface conversion: ir.Node is *ir.BasicLit, not *ir.ConstExpr

[578559967]

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

$ go version
go version go1.20 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/r/Library/Caches/go-build"
GOENV="/Users/r/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/r/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/r/go"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/Users/r/sdk/go1.20"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/r/sdk/go1.20/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/r/workspace/testcode/testinline/bug2.1/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/j_/rq9ph2cd3h50w468sgv34lwh0000gn/T/go-build2923148267=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.20 darwin/arm64
GOROOT/bin/go tool compile -V: compile version go1.20
uname -v: Darwin Kernel Version 22.2.0: Fri Nov 11 02:03:51 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T6000
ProductName:		macOS
ProductVersion:		13.1
BuildVersion:		22C65
lldb --version: lldb-1400.0.38.17
Apple Swift version 5.7.2 (swiftlang-5.7.2.135.5 clang-1400.0.29.51)

What did you do?

go.mod:

module foo

go 1.20

pkg/a.go:

package pkg

func Assert(msgAndArgs ...any) {
}

func Run() int {
        Assert("%v")
        return 0
}

func Run2() int {
        return Run()
}

b.go:

package main

import "foo/pkg"

var A = pkg.Run2()

func main() {
}

GOEXPERIMENT=nounified go1.20 build ./b.go

What did you expect to see?

Build successfully.

What did you see instead?

# command-line-arguments
./b.go:5:5: internal compiler error: panic: interface conversion: ir.Node is *ir.BasicLit, not *ir.ConstExpr

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

[cuonglm]

Sounds like the non-unified frontend importer import "%v" as an untyped constant: https://github.com/golang/go/blob/release-branch.go1.20/src/cmd/compile/internal/typecheck/iimport.go#L1283, while the unified IR frontend represents "%v" as a constant-fold - constant expression - node. That's why there's an ICE with GOEXPERIMENT=nounified.

The non-unified frontend is gone at tip, so I think there's nothing to do here.

cc @mdempsky

[randall77]

We should check 1.19. If it fails there we should arrange a backport for that.

[cuonglm]

We should check 1.19. If it fails there we should arrange a backport for that.

Inline static init is only added in 1.20, 1.19 have no effect.

[sywhang]

Can confirm this issue is only happening on Go 1.20 and is currently blocking Uber's upgrade to Go 1.20.

[cuonglm]

Can confirm this issue is only happening on Go 1.20 and is currently blocking Uber's upgrade to Go 1.20.

This only affects non-unified IR IIRC, do you set GOEXPERIMENT=nounified in your go build?

[sywhang]

do you set GOEXPERIMENT=nounified in your go build?

Unfortunately yes, we have some codegen based tooling that's seeing huge build time regression due to almost 10x regression in calling gcexportdata.Read when we do not set that.

[cuonglm]

do you set GOEXPERIMENT=nounified in your go build?

Unfortunately yes, we have some codegen based tooling that's seeing huge build time regression due to almost 10x regression in calling gcexportdata.Read when we do not set that.

Thanks for confirmation, I just worry there's another regression in Unified IR.

Note that GOEXPERIMENT=nounified will be gone in go1.21, so you may want to file new issue about that regression so we could take a look.

[sywhang]

Will do. We do have plans to migrate that codegen toolchain not rely on gcexportdata before 1.21 is out but we'll get back to you soon with some repro and profile after further investigation.

[sywhang]

An even simpler repro:

package main

import (
	"go.uber.org/zap"
)

var nopLogger = zap.NewNop()

func main() {
	nopLogger.Info("Hi")
}

[gopherbot]

Change https://go.dev/cl/466175 mentions this issue: cmd/compile/internal/staticinit: fix panic in interface conversion

[gopherbot]

Change https://go.dev/cl/466277 mentions this issue: cmd/compile: rename EvalConst to EvalExpr

[sywhang]

@mdempsky @cuonglm Thanks for the reviews. Can this be backported to Go 1.20 branch?

[cuonglm]

@mdempsky @cuonglm Thanks for the reviews. Can this be backported to Go 1.20 branch?

Let wait for the decision in #58439. The fix there will also fix this issue if backported.

[gopherbot]

Change https://go.dev/cl/467015 mentions this issue: cmd/compile: disable inline static init optimization

[gopherbot]

Change https://go.dev/cl/467016 mentions this issue: cmd/compile: reenable inline static init

[cuonglm]

CL https://go-review.googlesource.com/c/go/+/467035 is going to be backported, so I don't think we need to backport this one.