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

David Holmes david.holmes at oracle.com
Wed Nov 6 13:13:57 UTC 2019 

On 4/11/2019 8:27 pm, Magnus Ihse Bursie wrote:
> 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.

This change broke all cross-compilation.

David

> /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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>>>
>>>
>>
>

More information about the build-dev mailing list