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cmd/compile: ICE in SSA when make is invoked with negative value instead of runtime panic about "len out of range" #36259

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hideki1234 opened this issue Dec 24, 2019 · 1 comment
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@hideki1234
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@hideki1234 hideki1234 commented Dec 24, 2019

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

$ go version
go version go1.13.5 windows/amd64

Does this issue reproduce with the latest release?

Yes, it does

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

go env Output
$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=D:\Users\hidek\AppData\Local\go-build
set GOENV=D:\Users\hidek\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=D:\Users\hidek\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=D:\Users\hidek\bin\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=D:\Users\hidek\bin\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=D:\Users\hidek\AppData\Local\Temp\go-build088172418=/tmp/go-build -gno-record-gcc-switches

What did you do?

I compiled the code below:

package main

import (
    "fmt"
)

func rotate(s []int, m int) {
    l := len(s)
    m = m % l
    buf := make([]int, m)

    copy(buf, s)
    copy(s, s[m:])
    copy(s[l-m:], buf)
}

func testRotate() {
    a0 := [...]int{1,2,3,4,5}
    fmt.Println(a0)

    rotate(a0[:], 1)
    fmt.Println(a0)

    rotate(a0[:], -3)
    fmt.Println(a0)
}

func main() {
    testRotate()
}

What did you expect to see?

rotate(a0[:], -3) is unsafe because it can result in calling make with a negative value. So I expected a runtime error or a meaningful compile error/warning message.

What did you see instead?

I got an internal compiler error:

# command-line-arguments
.\ex4-4.go:21:11: internal compiler error: 'testRotate': not lowered: v281, Move SSA UNSAFEPTR PTR SSA

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

@gopherbot
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@gopherbot gopherbot commented Dec 24, 2019

Change https://golang.org/cl/212405 mentions this issue: cmd/compile: avoid memmove -> SSA move rewrite when size is negative

@odeke-em odeke-em added this to the Go1.15 milestone Dec 24, 2019
@odeke-em odeke-em changed the title Internal compiler error cmd/compile: ICE in SSA when make is invoked with negative value instead of runtime panic about "len out of range" Dec 24, 2019
@cagedmantis cagedmantis added the NeedsFix label Jan 2, 2020
@gopherbot gopherbot closed this in bc98e35 Feb 24, 2020
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