go: cmd/compile: uncaught RuntimeError: memory access out of bounds

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

$ go version
go version go1.14.1 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/hajimehoshi/Library/Caches/go-build"
GOENV="/Users/hajimehoshi/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/hajimehoshi/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
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/ht/ky_bwgzs4bd5z1hh02k34x_h0000gn/T/go-build937690981=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Build this Go program as Wasm and run it on a browser several times:

package main

import (
        "fmt"
        "time"
)

func main() {
        ch1 := make(chan string)
        ch2 := make(chan string)
        ch3 := make(chan struct{})

        go func() {
                for {
                        time.Sleep(5 * time.Millisecond)
                        ch1 <- "A"
                }
        }()
        go func() {
                for {
                        time.Sleep(7 * time.Millisecond)
                        ch2 <- "B"
                }
        }()
        go func() {
                for {
                        time.Sleep(3 * time.Second)
                        close(ch3)
                }
        }()

loop:
        for {
                select {
                case str := <-ch1:
                        fmt.Println(str)
                case str := <-ch2:
                        fmt.Println(str)
                case <-ch3:
                        fmt.Println("Done")
                        break loop
                }
        }
}

What did you expect to see?

No error (except for ‘already exit’)

What did you see instead?

Sometimes I saw this error:

Uncaught RuntimeError: memory access out of bounds
    at runtime.__waitq_.dequeue (wasm-function[113]:0xbe09)
    at runtime.chanrecv (wasm-function[109]:0xab34)
    at runtime.chanrecv1 (wasm-function[108]:0xa89b)
    at syscall.fsCall (wasm-function[1636]:0x12510e)
    at syscall.Write (wasm-function[1634]:0x12471b)
    at internal_poll.__FD_.Write (wasm-function[1657]:0x128d1e)
    at os.__File_.Write (wasm-function[1669]:0x129ef2)
    at fmt.Fprintln (wasm-function[1700]:0x131eb1)
    at main.main (wasm-function[1720]:0x14065c)
    at wasm_pc_f_loop (wasm-function[950]:0xc3a5f)


  | runtime.__waitq_.dequeue | @ | 008b857e-113:116
  | runtime.chanrecv | @ | 008b857e-109:249
  | runtime.chanrecv1 | @ | 008b857e-108:37
  | syscall.fsCall | @ | 008b857e-1636:354
  | syscall.Write | @ | 008b857e-1634:451
  | internal_poll.__FD_.Write | @ | 008b857e-1657:385
  | os.__File_.Write | @ | 008b857e-1669:164
  | fmt.Fprintln | @ | 008b857e-1700:170
  | main.main | @ | 008b857e-1720:471
  | wasm_pc_f_loop | @ | 008b857e-950:14
  | wasm_export_resume | @ | 008b857e-949:5
  | _resume | @ | wasm_exec.js:544
  | (anonymous) | @ | wasm_exec.js:308
  | setTimeout (async) |   |  
  | runtime.scheduleTimeoutEvent | @ | wasm_exec.js:306
  | runtime.scheduleTimeoutEvent | @ | 008b857e-969:6
  | runtime.beforeIdle | @ | 008b857e-158:107
  | runtime.findrunnable | @ | 008b857e-564:1278
  | runtime.schedule | @ | 008b857e-569:960
  | runtime.park_m | @ | 008b857e-572:245
  | runtime.mcall | @ | 008b857e-899:77
  | runtime.gopark | @ | 008b857e-515:312
  | runtime.selectgo | @ | 008b857e-655:2335
  | main.main | @ | 008b857e-1720:349
  | wasm_pc_f_loop | @ | 008b857e-950:14
  | wasm_export_resume | @ | 008b857e-949:5
  | _resume | @ | wasm_exec.js:544
  | (anonymous) | @ | wasm_exec.js:308
...