cmd/compile: internal compiler error: unexpected type uint for 1

[zeebo]

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

$ go version
go version devel +9a00e64633 Fri Jul 5 12:11:36 2019 +0000 linux/amd6

Does this issue reproduce with the latest release?

No.

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

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/jeff/.cache/go-build"
GOENV="/home/jeff/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/jeff/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org"
GOROOT="/home/jeff/gotip"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/jeff/gotip/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/jeff/tmp/crash/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-build477512344=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

import "unsafe"

func main() {
	var l uint64
	var p unsafe.Pointer
	_ = unsafe.Pointer(uintptr(p) + (uintptr(l) >> 1))
}

What did you expect to see?

Successful compilation.

What did you see instead?

# crash
./foo.go:10:20: internal compiler error: unexpected type uint for 1

goroutine 1 [running]:
runtime/debug.Stack(0xfdc4a0, 0xc0000b6008, 0x0)
	/home/jeff/gotip/src/runtime/debug/stack.go:24 +0x9d
cmd/compile/internal/gc.Fatalf(0xe45afa, 0x19, 0xc0003491b8, 0x2, 0x2)
	/home/jeff/gotip/src/cmd/compile/internal/gc/subr.go:188 +0x291
cmd/compile/internal/gc.(*Escape).unsafeValue(0xc0000f2210, 0xc0000f2278, 0x0, 0xc000360d80)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:597 +0x2a7
cmd/compile/internal/gc.(*Escape).unsafeValue(0xc0000f2210, 0xc0000f2278, 0x0, 0xc000360a80)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:619 +0xc8
cmd/compile/internal/gc.(*Escape).unsafeValue(0xc0000f2210, 0xc0000f2278, 0x0, 0xc000360b80)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:619 +0xc8
cmd/compile/internal/gc.(*Escape).exprSkipInit(0xc0000f2210, 0xc0000f2278, 0x0, 0xc000360780)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:480 +0x723
cmd/compile/internal/gc.(*Escape).expr(0xc0000f2210, 0xc0000f2278, 0x0, 0xc000360780)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:414 +0x6a
cmd/compile/internal/gc.(*Escape).assign(0xc0000f2210, 0xc00033d0e0, 0xc000360780, 0xe35d70, 0x6, 0xc000360700)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:702 +0x17b
cmd/compile/internal/gc.(*Escape).stmt(0xc0000f2210, 0xc000360700)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:364 +0x27c
cmd/compile/internal/gc.(*Escape).stmts(0xc0000f2210, 0xc00037c7a0)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:403 +0x58
cmd/compile/internal/gc.(*Escape).walkFunc(0xc0000f2210, 0xc0002e2160)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:204 +0x78
cmd/compile/internal/gc.escapeFuncs(0xc0000b6450, 0x1, 0x1, 0xc0002e4900)
	/home/jeff/gotip/src/cmd/compile/internal/gc/escape.go:145 +0x117
cmd/compile/internal/gc.(*bottomUpVisitor).visit(0xc0003497a8, 0xc0002e2160, 0xbf402d1f18dba43e)
	/home/jeff/gotip/src/cmd/compile/internal/gc/scc.go:118 +0x295
cmd/compile/internal/gc.visitBottomUp(0xc000094a20, 0x2, 0x2, 0xe5b258)
	/home/jeff/gotip/src/cmd/compile/internal/gc/scc.go:58 +0x95
cmd/compile/internal/gc.escapes(...)
	/home/jeff/gotip/src/cmd/compile/internal/gc/esc.go:49
cmd/compile/internal/gc.Main(0xe5b0c8)
	/home/jeff/gotip/src/cmd/compile/internal/gc/main.go:646 +0x2f42
main.main()
	/home/jeff/gotip/src/cmd/compile/main.go:51 +0xac

[agnivade]

Marked as release blocker since this is a regression.

@randall77

[agnivade]

Bisected to 996a687

It passes with -gcflags=all=-newescape=false

@mdempsky @dr2chase

[mdempsky]

Thanks for the easy repro and bisection, @zeebo @agnivade.

I think the fix is in unsafeValue, for OLSH and ORSH nodes we should call discard(n.Right) instead of unsafeValue(n.Right).

[gopherbot]

Change https://golang.org/cl/185039 mentions this issue: cmd/compile: fix unsafeValue handles OLSH/ORSH wrong