x/tools/go/pointer: internal error (panic) in pointer analysis - not a tagged object

[zyq823]

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

$ go version 

go1.15.2 linux/amd64

Does this issue reproduce with the latest release?

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

go env Output

$ go env
GO111MODULE=""

GOARCH="amd64"

GOBIN=""

GOCACHE="/home/xxx/.cache/go-build"

GOENV="/home/xxx/.config/go/env"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOINSECURE=""

GOMODCACHE="/home/xxx/go/pkg/mod"

GONOPROXY=""

GONOSUMDB=""

GOOS="linux"

GOPATH="/home/xxx/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"

GCCGO="gccgo"

AR="ar"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/home/xxx/Downloads/research/xx/istio/go.mod"

CGO_CFLAGS="-g -O2"

CGO_CPPFLAGS=""

CGO_CXXFLAGS="-g -O2"

CGO_FFLAGS="-g -O2"

CGO_LDFLAGS="-g -O2"

PKG_CONFIG="pkg-config"

GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build086903914=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Running a go analyzer I wrote that incorporates the pointer package, on the istio codebase

What did you expect to see?

Error-free analysis that utilizes Go's pointer analysis package.

What did you see instead?

A panic error in the pointer analysis package was triggered. As shown below,

Internal panic in pointer analysis:
goroutine 1 [running]:
runtime/debug.Stack(0x24, 0x0, 0x0)
/usr/local/go/src/runtime/debug/stack.go:24 +0x9f
runtime/debug.PrintStack()
/usr/local/go/src/runtime/debug/stack.go:16 +0x25
golang.org/x/tools/go/pointer.Analyze.func1(0xc1fad78658)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/analysis.go:227 +0x10b
panic(0x6cc900, 0xc054a07080)
/usr/local/go/src/runtime/panic.go:969 +0x175
golang.org/x/tools/go/pointer.(*analysis).taggedValue(0xc0f5566a80, 0xc00009dacb, 0x4, 0x64, 0xc07c8d8700)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/gen.go:272 +0x105
golang.org/x/tools/go/pointer.(*typeFilterConstraint).solve(0xc0b7ae0940, 0xc0f5566a80, 0xc08e16d940)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/solve.go:273 +0xcc
golang.org/x/tools/go/pointer.(*analysis).solveConstraints(0xc0f5566a80, 0xc09b797620, 0xc08e16d940)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/solve.go:165 +0x178
golang.org/x/tools/go/pointer.(*analysis).solve(0xc0f5566a80)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/solve.go:59 +0x1ad
golang.org/x/tools/go/pointer.Analyze(0xc0f5a34a00, 0x0, 0x790a20, 0xc054a070b0)
/home/xxx/go/pkg/mod/golang.org/x/tools@v0.0.0-20200806022845-90696ccdc692/go/pointer/analysis.go:331 +0x4bc
main.(*analysis).pointerAnalysis(0xc000f42960, 0x798860, 0xc0eb11c660, 0x0, 0x797ea0, 0xc0eae465f0)
/home/xxx/Downloads/research/go2/race_checker/pointerAnalysis.go:25 +0x125
main.(*analysis).insMakeInterface(0xc000f42960, 0xc0eae465f0, 0x0, 0x797ea0, 0xc0eae465f0)
/home/xxx/Downloads/research/go2/race_checker/ssaInstructions.go:317 +0x1ac
main.(*analysis).visitAllInstructions(0xc000f42960, 0xc0786d5040, 0x0)
/home/xxx/Downloads/research/go2/race_checker/staticAnalysis.go:414 +0x1b1e
main.(*analysis).insCall(0xc000f42960, 0xc0931fb800, 0x0, 0x797240, 0xc0931fb800, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
/home/xxx/Downloads/research/go2/race_checker/ssaInstructions.go:394 +0x452
main.(*analysis).visitAllInstructions(0xc000f42960, 0xc0786f3b80, 0x0)
/home/xxx/Downloads/research/go2/race_checker/staticAnalysis.go:416 +0x1da5
main.staticAnalysis(0xc0000ae030, 0x0, 0x0, 0x1, 0x0)
/home/xxx/Downloads/research/go2/race_checker/staticAnalysis.go:134 +0x99c
main.main()
/home/xxx/Downloads/research/go2/race_checker/main.go:150 +0x26d
FATA[13:01:11] internal error in pointer analysis: not a tagged object: n645835 (please report this bug)

[ianlancetaylor]

Can you show us how to recreate the problem ourselves? Thanks.

[ianlancetaylor]

CC @alandonovan @matloob

[zyq823]

Here is a synopsis of some code in my program that led to the panic. I was testing it on istio (upon building binary file in istio/istioctl/cmd/istioctl)

type pa struct {
	ptaConfig	*pointer.Config
}

func main() {
	flag.Parse()
	args := flag.Args()
	cfg := &packages.Config{
		Mode:  packages.LoadAllSyntax, 
		Dir:   "",     
		Tests: false,  
	}

	initial, _ := packages.Load(cfg, args...)
	prog, pkgs := ssautil.AllPackages(initial, 0)
	prog.Build()

	var mains []*ssa.Package
	for _, p := range pkgs {
		if p != nil && p.Pkg.Name() == "main" && p.Func("main") != nil {
			mains = append(mains, p)
		}
	}

	fn := mains[0].Func("main")
	config := &pointer.Config{
		Mains:	mains,
	}

	PTA := &pa {
		ptaConfig: config,
	}
	PTA.visitFn(fn)
}

func (p *pa) visitFn(fn *ssa.Function) {
	if fn != nil && (fn.Name() == "main" || fn.Name() == "ConfigAndEnvProcessing" || fn.Name() == "GetExitCode") {
		basicBlocks := fn.Blocks
		for k := 0; k < len(basicBlocks); k++ {
			b := basicBlocks[k]
			for _, i := range b.Instrs {
				switch ins := i.(type) {
				case *ssa.Call:
					p.visitFn(ins.Call.StaticCallee())
				case *ssa.MakeInterface:
					switch insT := ins.X.(type) {
					case *ssa.UnOp:
						if pointer.CanPoint(ins.X.Type()) {
							p.ptaConfig.AddQuery(ins.X)
						}
						if _, ok := insT.X.(*ssa.Global); !ok {
							result, _ := pointer.Analyze(p.ptaConfig)
							_ = result
						}
					}
				default:
					continue
				}
			}
		}
	}
}

[MyLGG]

anybody else can solve this problem now? I also meet the same problem when use x/tools/go/pointer

[zpavlinovic]

The information here is helpful, but I wonder if we can get a minimal reproducible example. @MyLGG, do you perhaps have an example like that or the bug you are seeing also manifests on istio code base?

[gopherbot]

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