go: cmd/compile: fatal error: out of memory on reslice with negative index

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

$ go version
go version go1.11.2 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/ccooper/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/ccooper/work/polaris"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/kz/p8_8brl12k1gjbc79cjvpdtr0000gn/T/go-build092783061=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Performed a reslice with a negative index.

https://play.golang.org/p/6TIXJwN55zR

What did you expect to see?

1 -1 panic: runtime error: slice bounds out of range

What did you see instead?

1 -1 fatal error: out of memory

runtime stack: runtime.throw(0x10c30b4, 0xd) /usr/local/go/src/runtime/panic.go:608 +0x72 runtime.largeAlloc(0xfffffffffffffffe, 0x1040100, 0x11be000) /usr/local/go/src/runtime/malloc.go:1007 +0x181 runtime.mallocgc.func1() /usr/local/go/src/runtime/malloc.go:914 +0x46 runtime.systemstack(0x0) /usr/local/go/src/runtime/asm_amd64.s:351 +0x66 runtime.mstart() /usr/local/go/src/runtime/proc.go:1229

goroutine 1 [running]: runtime.systemstack_switch() /usr/local/go/src/runtime/asm_amd64.s:311 fp=0xc00007ae18 sp=0xc00007ae10 pc=0x104eae0 runtime.mallocgc(0xfffffffffffffffe, 0x0, 0x0, 0x0) /usr/local/go/src/runtime/malloc.go:913 +0x896 fp=0xc00007aeb8 sp=0xc00007ae18 pc=0x100aaa6 runtime.slicebytetostring(0x0, 0xc000014099, 0xfffffffffffffffe, 0x7, 0x0, 0x0) /usr/local/go/src/runtime/string.go:102 +0x9f fp=0xc00007aee8 sp=0xc00007aeb8 pc=0x103e9af main.main() /Users/ccooper/work/polaris/src/github.com/alistanis/oom/main.go:12 +0x173 fp=0xc00007af98 sp=0xc00007aee8 pc=0x10910c3 runtime.main() /usr/local/go/src/runtime/proc.go:201 +0x207 fp=0xc00007afe0 sp=0xc00007af98 pc=0x10287c7 runtime.goexit() /usr/local/go/src/runtime/asm_amd64.s:1333 +0x1 fp=0xc00007afe8 sp=0xc00007afe0 pc=0x1050a21 exit status 2

I would expect this to fail in either case, but I was surprised by the error message. I found it when I mistakenly missed a bounds check on a reslice and thought I had actually reached an out of memory issue - the machine I was using had ~200MB of free RAM so I thought that was actually the case at first.