llvm dev - Jan 2022 - Is profile data collection broken in clang-13?

Hello,  I hop that this is the right place to ask this...


My system is Ubuntu 20.04.

I have a pretty standard build process for some C++ targets that runs a 
bunch of tests with instrumentation enabled (-fprofile-instr-generate 
and -fcoverage-mapping on compile and link) which has been working fine 
up until I changed from clang-12 to clang-13 tools.


Now llvm-profdata merge reports "warning: file.profraw: malformed 
instrumentation profile data" for each profraw file.


The only change is the tool chain.


"file" describes the profraw files as LLVM raw profile data, version
6. 
Running any other version of llvm-profdata produces "unsupported 
instrumentation profile format version" warnings, so the profraw file 
generation appears to be correctly generated.


Thanks,

Ian

Hi Ian,

I encountered the same issue after upgrading to clang-13. In my case the
problem was related to profiling an application with a shared library. I
believe the profraw file gets corrupted when two binaries (main executable
and a shared library) are accessing it.

My solution is to add %m to LLVM_PROFILE_FILE. This way each binary will be
using independent profile files.

See bug report: https://github.com/llvm/llvm-project/issues/50966.

Before clang-13 this scenario was working, but I'm not sure this was
intended and supported.

Bests,
Paweł

On Wed, Jan 5, 2022 at 8:57 AM Ian Collins via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello,  I hop that this is the right place to ask this...
>
>
> My system is Ubuntu 20.04.
>
> I have a pretty standard build process for some C++ targets that runs a
> bunch of tests with instrumentation enabled (-fprofile-instr-generate
> and -fcoverage-mapping on compile and link) which has been working fine
> up until I changed from clang-12 to clang-13 tools.
>
>
> Now llvm-profdata merge reports "warning: file.profraw: malformed
> instrumentation profile data" for each profraw file.
>
>
> The only change is the tool chain.
>
>
> "file" describes the profraw files as LLVM raw profile data,
version 6.
> Running any other version of llvm-profdata produces "unsupported
> instrumentation profile format version" warnings, so the profraw file
> generation appears to be correctly generated.
>
>
> Thanks,
>
> Ian
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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