llvm dev - Jul 2018 - profiling JIT compiled code with perf

Have you seen https://reviews.llvm.org/D44892? we are using it in Julia to
use perf on jitted code.

-Valentin

On Wed, 18 Jul 2018 at 17:13 Frank Tetzel via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> > Hello,
> >
> > is there any support in LLVM for the jitdump format [1] of perf?
> >
> > It enables perf report to also "zoom in" and annotate the
JIT compiled
> > code on assembly level with runtime percentage. It helps a lot to
> > understand which parts of the generated code is the bottleneck.
> >
> > I recently did a proof-of-concept for the JIT assembler asmjit [2]. It
> > just dumps the generated code in the right format and mmaps the file
> > to let perf record know about it. perf report picks it up
> > automatically.
> >
> > So, is there any profiling support for JIT compiled code?
>
>
> I guess that's a no.
>
> Is there a simple way to get a pointer to the assemble code and the
> exact size in bytes? Or should I just use the function pointer? Where
> do I get the size?
>
> Then I could at least dump the native code. Profiling on assembly level
> would already help a lot.
>
> Regards,
> Frank
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> Have you seen https://reviews.llvm.org/D44892? we are using it in
> Julia to use perf on jitted code.
No, I did not see this patch before. Thanks a lot for the pointer.

It seems to be doing exactly what I want. Let's see if I get it working.

Best regards,
Frank

Hi,

On 2018-07-19 14:57:42 +0200, Frank Tetzel via llvm-dev
wrote:
> > Have you seen https://reviews.llvm.org/D44892? we are using it in
> > Julia to use perf on jitted code.
> 
> No, I did not see this patch before. Thanks a lot for the pointer.
> 
> It seems to be doing exactly what I want. Let's see if I get it
working.
FWIW, I just merged this.  Did you have any luck getting it to work?

Greetings,

Andres Freund