[Mesa-dev] How difficult would it be to have debugging information for Jitted code show up?

[Emil Velikov]

On 14 November 2014 01:48, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> Hi Steven,
>
> On 14 November 2014 01:40, Steven Stewart-Gallus
> <sstewartgallus00 at mylangara.bc.ca> wrote:
>> But my distribution does build Mesa with debugging symbols. I have the package
>> libgl1-mesa-dri-dbg installed which gives me debugging symbols such as
>> drm_intel_bo_wait_rendering and drm_intel_bo_subdata. I assume I don't have is
>> debugging information for JITted code although maybe the problem is a bug in
>> perf (they've had problems with artificial intrinsics before.) Please assume I
>> have at least the small quantity of intelligence needed to have installed the
>> debugging symbols for the library I a. But tell me, what do you see when you
>> profile glxgears with perf?
>>
> Let me put things a bit differently: the classic drivers (be that i965
> or any other) do _not_ use LLVM. So when you say that there are no
> debug symbols for the JITted code. that does not make sense for
> most(all?) people thus they assume the closest thing. Which is that
> you're missing the debug symbols, therefore giving you instructions on
> how to get them(rebuild mesa).
>
> So can you please tell us what makes you think that using the i965
> driver, goes into LLVM/JITted code ?
> Perhaps having some sort of backtrace (I know the some functions names
> will be ??) or a testcase might bring some light :)
>
For anyone interested/hitting this issue:
It seems that the debug package did not provide the relevant files,
causing this misunderstanding.
Now that I think about it seems to be the exact same issue about
Debian's build/packaging system [1].
So as a note of self - don't trust your distribution to always get it
right, double check :P


-Emil

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=755921