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

[serguei.spit...@oracle.com]

Hi Yasumasa,

This change looks good.
Even though it seems to be not impacting platforms other than Linux
it is better to make sure it is built Okay on all platforms.

Thanks,
Serguei


On 11/1/19 01:56, 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