runtime: GDBPython test failed on linux/arm64

[mengzhuo]

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

go version devel +f58b02a29c Sun Nov 11 18:49:40 2018 +0000 linux/arm64

Does this issue reproduce with the latest release?

no

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

GOARCH="arm64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/go"
GOPROXY=""
GORACE=""
GOROOT="/root/godev"
GOTMPDIR=""
GOTOOLDIR="/root/godev/pkg/tool/linux_arm64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
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 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build549632965=/tmp/go-build -gno-record-gcc-switches"

What did you do?

./all.bash -v

What did you expect to see?

all tests passed.

What did you see instead?

--- FAIL: TestGdbPython (4.37s)
    runtime-gdb_test.go:66: gdb version 8.1
    runtime-gdb_test.go:213: gdb output: Loading Go Runtime support.
        Loaded  Script
        Yes     /root/godev/src/runtime/runtime-gdb.py
        Breakpoint 1 at 0x8f018: file /tmp/go-build158656782/main.go, line 15.
        [New LWP 25349]
        [New LWP 25358]
        [New LWP 25359]
        [New LWP 25360]
        hi
        [New LWP 25363]

        Thread 1 "a.exe" hit Breakpoint 1, main.main () at /tmp/go-build158656782/main.go:17
        17              gslice = slicevar
        BEGIN info goroutines
        * 1 running  syscall.Syscall
          2 runnable runtime.forcegchelper
          17 waiting  runtime.gopark
          18 waiting  runtime.gopark
        END
        BEGIN print mapvar
        $1 = map[string]string = {["ghi"] = "jkl", ["abc"] = "def"}
        END
        BEGIN print strvar
        $2 = "abc"
        END
        BEGIN info locals
        mapvar = map[string]string = {["ghi"] = "jkl", ["abc"] = "def"}
        strvar = "abc"
        slicevar =  []stringTraceback (most recent call last):
          File "/root/godev/src/runtime/runtime-gdb.py", line 134, in children
            if sval.len > sval.cap:
          File "/root/godev/src/runtime/runtime-gdb.py", line 84, in len
            return int(self.val['len'])
        gdb.error: value has been optimized out
        END

        BEGIN goroutine 1 bt
        #0  main.main () at /tmp/go-build158656782/main.go:17
        END
        BEGIN goroutine 2 bt
        #0  runtime.forcegchelper () at /root/godev/src/runtime/proc.go:242
        #1  0x000000000008f018 in fmt.Println (a=..., n=<optimized out>, err=...) at /root/godev/src/fmt/print.go:275
        #2  main.main () at /tmp/go-build158656782/main.go:14
        Traceback (most recent call last):
          File "/root/godev/src/runtime/runtime-gdb.py", line 536, in invoke
            gdb.parse_and_eval('$sp = $save_sp')
        gdb.error: Attempt to assign to an unmodifiable value.
        Error occurred in Python command: Attempt to assign to an unmodifiable value.
        END
        Breakpoint 2 at 0x8f058: file /tmp/go-build158656782/main.go, line 18.
        runtime: newstack sp=0x4000040fd0 stack=[0x4000090000, 0x4000091000]
                morebuf={pc:0x8f018 sp:0x4000040fd0 lr:0x0}
                sched={pc:0x37bec sp:0x4000040fd0 lr:0x8f018 ctxt:0x0}
        runtime: gp=0x4000000180, goid=1, gp->status=0x2
         runtime: split stack overflow: 0x4000040fd0 < 0x4000090000
        fatal error: runtime: split stack overflow

        runtime stack:
        runtime.throw(0xc4dee, 0x1d)
                /root/godev/src/runtime/panic.go:608 +0x54
        runtime.newstack()
                /root/godev/src/runtime/stack.go:995 +0x718
        runtime.morestack()
                /root/godev/src/runtime/asm_arm64.s:309 +0x70

        goroutine 1 [running]:
        runtime.forcegchelper()
                /root/godev/src/runtime/proc.go:242 +0x12c fp=0x4000040fd0 sp=0x4000040fd0 pc=0x37bec
        runtime: unexpected return pc for main.main called from 0x0
        stack: frame={sp:0x4000040fd0, fp:0x4000041080} stack=[0x4000090000,0x4000091000)

        fmt.Println(...)
                /root/godev/src/fmt/print.go:275
        main.main()
                /tmp/go-build158656782/main.go:14 +0x1c8 fp=0x4000041080 sp=0x4000040fd0 pc=0x8f018
        [LWP 25363 exited]
        [LWP 25360 exited]
        [LWP 25359 exited]
        [LWP 25358 exited]
        [LWP 25349 exited]
        [Inferior 1 (process 25331) exited with code 02]
        BEGIN goroutine 1 bt at the end
        No such goroutine:  1
        END

    runtime-gdb_test.go:286: goroutine 1 bt at the end failed: No such goroutine:  1
FAIL
FAIL    runtime 45.405s