RFR: 8233285: Demangling C++ symbols in jhsdb jstack --mixed

Mon Nov 4 10:27:44 UTC 2019

On 2019-11-02 13:43, Daniel D. Daugherty wrote:
> Since this review contains build changes, I've added build-dev at ...
Thanks Dan for noticing this and cc:ing us.

Yasumasa: build changes look fine. Thanks.

/Magnus
>
> Dan
>
>
> On 11/1/19 4:56 AM, Yasumasa Suenaga wrote:
>> (Changed subject to review request)
>>
>> Hi,
>>
>> I converted LinuxDebuggerLocal.c to C++ code, and it works fine on 
>> submit repo.
>> (mach5-one-ysuenaga-JDK-8233285-1-20191101-0746-6336009)
>>
>>   http://cr.openjdk.java.net/~ysuenaga/JDK-8233285/webrev.00/
>>
>> Could you review it?
>>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> On 2019/11/01 8:54, Yasumasa Suenaga wrote:
>>> Hi David,
>>>
>>> On 2019/11/01 7:55, David Holmes wrote:
>>>> Hi Yasumasa,
>>>>
>>>> New build dependencies cannot be added lightly. This impacts 
>>>> everyone who maintains build/test farms.
>>>
>>> Ok, thanks for telling it.
>>>
>>>> We already use the C++ demangling capabilities in the VM. Is there 
>>>> some way to export that for use by libsaproc ?
>>>>
>>>> Otherwise using C++ demangle may still be the better choice given 
>>>> we already have it as a dependency.
>>>
>>> I found abi::__cxa_demangle() is used in ElfDecoder::demangle() at 
>>> decoder_linux.cpp .
>>> It is similar with my original proposal.
>>>
>>>>>>>>>> http://cr.openjdk.java.net/~ysuenaga/sa-demangle/
>>>
>>> I agree with David to use C++ demangle way.
>>> However we need to choice the fix from following:
>>>
>>>    A. Convert LinuxDebuggerLocal.c to C++ code
>>>    B. Add C++ code for libsaproc.so to demangle symbols.
>>>
>>> I've discussed with Chris about it in [1].
>>> Option A might be large change.
>>>
>>>
>>> Thanks,
>>>
>>> Yasumasa
>>>
>>>
>>> [1] 
>>> https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-October/029716.html
>>>
>>>
>>>> David
>>>>
>>>> On 1/11/2019 12:58 am, Chris Plummer wrote:
>>>>> Hi Yasumasa,
>>>>>
>>>>> Here's the failure during configure:
>>>>>
>>>>> [2019-10-31T06:07:45,131Z] checking demangle.h usability... no
>>>>> [2019-10-31T06:07:45,150Z] checking demangle.h presence... no
>>>>> [2019-10-31T06:07:45,150Z] checking for demangle.h... no
>>>>> [2019-10-31T06:07:45,151Z] configure: error: Could not find 
>>>>> demangle.h! You might be able to fix this by running 'sudo yum 
>>>>> install binutils-devel'.
>>>>>
>>>>> Chris
>>>>>
>>>>>
>>>>> On 10/31/19 1:08 AM, Yasumasa Suenaga wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I filed this enhancement to JBS:
>>>>>>
>>>>>>   https://bugs.openjdk.java.net/browse/JDK-8233285
>>>>>>
>>>>>> Also I pushed the changes to submit repo, but it was failed.
>>>>>>
>>>>>>   http://hg.openjdk.java.net/jdk/submit/rev/bfbc49233c26
>>>>>>   http://hg.openjdk.java.net/jdk/submit/rev/430e4f65ef25
>>>>>>
>>>>>> According to the email from Mach 5, dependency errors were 
>>>>>> occurred in jib.
>>>>>> Can someone share the details?
>>>>>> I'm not familiar in jib, so I want help.
>>>>>>
>>>>>>   mach5-one-ysuenaga-JDK-8233285-20191031-0606-6301426
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Yasumasa
>>>>>>
>>>>>>
>>>>>> On 2019/10/31 11:23, Chris Plummer wrote:
>>>>>>> You can change the configure script. I don't know if there's any 
>>>>>>> concerns with using libiberty.a. That's possibly a legal 
>>>>>>> question (GNU GPL). You might want to ask that on jdk-dev and/or 
>>>>>>> build-dev.
>>>>>>>
>>>>>>> Chris
>>>>>>>
>>>>>>> On 10/30/19 7:14 PM, Yasumasa Suenaga wrote:
>>>>>>>> Hi Chris,
>>>>>>>>
>>>>>>>> Thanks for quick reply!
>>>>>>>>
>>>>>>>> If we convert LinuxDebuggerLocal.c to C++ code, we have to 
>>>>>>>> convert a lot of JNI calls to C++ style.
>>>>>>>> For example:
>>>>>>>>
>>>>>>>>   (*env)->FindClass(env, "java/lang/String")
>>>>>>>>       to
>>>>>>>>   env->FindClass("java/lang/String")
>>>>>>>>
>>>>>>>> Can it be accepted?
>>>>>>>>
>>>>>>>> OTOH I said in my email, to use cplus_demangle(), we need to 
>>>>>>>> link libiberty.a which is provided by binutils. Thus I think we 
>>>>>>>> need to check libiberty.a in configure script. Is it ok?
>>>>>>>>
>>>>>>>>
>>>>>>>> I prefer to use cplus_demangle() if we can change configure 
>>>>>>>> script.
>>>>>>>>
>>>>>>>>
>>>>>>>> Yasumasa
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2019/10/31 11:03, Chris Plummer wrote:
>>>>>>>>> Hi Yasumasa,
>>>>>>>>>
>>>>>>>>> I don't have concerns with adding C++ source to SA, but in 
>>>>>>>>> order to do so you've put the new native code in its own file 
>>>>>>>>> rather than in LinuxDebuggerLocal.c. I'd like to see that 
>>>>>>>>> resolved. So either convert LinuxDebuggerLocal.c to C++, or 
>>>>>>>>> use cplus_demangle().
>>>>>>>>>
>>>>>>>>> thanks,
>>>>>>>>>
>>>>>>>>> Chris
>>>>>>>>>
>>>>>>>>> On 10/30/19 6:54 PM, Yasumasa Suenaga wrote:
>>>>>>>>>> Hi all,
>>>>>>>>>>
>>>>>>>>>> I saw C++ frames in `jhsdb jstack --mixed`, and they were 
>>>>>>>>>> mangled as below:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 0x00007ff255a8fa4c 
>>>>>>>>>> _ZN9JavaCalls11call_helperEP9JavaValueRK12methodHandleP17JavaCallArgumentsP6Thread 
>>>>>>>>>> + 0x6ac
>>>>>>>>>> 0x00007ff255a8cc1d 
>>>>>>>>>> _ZN9JavaCalls12call_virtualEP9JavaValueP5KlassP6SymbolS5_P17JavaCallArgumentsP6Thread 
>>>>>>>>>> + 0x33d
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> We can demangle them via c++filt, but I think it is more 
>>>>>>>>>> convenience if jstack can show demangling symbols.
>>>>>>>>>> I think we can demangle in jstack with this patch. If it is 
>>>>>>>>>> accepted, I will file it to JBS and send review request.
>>>>>>>>>> What do you think?
>>>>>>>>>>
>>>>>>>>>> http://cr.openjdk.java.net/~ysuenaga/sa-demangle/
>>>>>>>>>>
>>>>>>>>>> We can get the stack as below after applying this patch:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 0x00007ff1aba20a4c JavaCalls::call_helper(JavaValue*, 
>>>>>>>>>> methodHandle const&, JavaCallArguments*, Thread*) + 0x6ac
>>>>>>>>>> 0x00007ff1aba1dc1d JavaCalls::call_virtual(JavaValue*, 
>>>>>>>>>> Klass*, Symbol*, Symbol*, JavaCallArguments*, Thread*) + 0x33d
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I use abi::__cxa_demangle() for demangling, so this patch 
>>>>>>>>>> adds C++ source to SA.
>>>>>>>>>> If it is not comfortable, we can use cplus_demangle().
>>>>>>>>>> But this function is provided by libiberty.a, so we need to 
>>>>>>>>>> link it to libsaproc and need to check libiberty.a in 
>>>>>>>>>> configure script.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Thanks,
>>>>>>>>>>
>>>>>>>>>> Yasumasa
>>>>>>>>>
>>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>>>
>>
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