Thread overview
Does LDC support profiling at all?
Dec 22
Nathan S.
December 22
DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :)

Thanks.


December 22
On Friday, 22 December 2017 at 09:52:26 UTC, Chris Katko wrote:
> DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :)
>
> Thanks.

Is -fprofile-instr-generate=<place to write profile> what you're looking for?
December 23
On Friday, 22 December 2017 at 09:52:26 UTC, Chris Katko wrote:
> DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :)

Fine grained PGO profiling:
-fprofile-instr-generate
http://johanengelen.github.io/ldc/2016/07/15/Profile-Guided-Optimization-with-LDC.html

Function entry/exit profiling:
-finstrument-functions
https://github.com/ldc-developers/ldc/issues/1839
https://www.youtube.com/watch?v=LNav5qvyK7I

I suspect it is not too much effort to add DMD's -profile and -profile=gc to LDC, but noone has done it yet.

Another thing that is relatively easy to add to LDC: https://llvm.org/docs/XRay.html

-Johan


December 23
On Saturday, 23 December 2017 at 12:23:33 UTC, Johan Engelen wrote:
> Fine grained PGO profiling:
> -fprofile-instr-generate
> http://johanengelen.github.io/ldc/2016/07/15/Profile-Guided-Optimization-with-LDC.html
>
> Function entry/exit profiling:
> -finstrument-functions
> https://github.com/ldc-developers/ldc/issues/1839
> https://www.youtube.com/watch?v=LNav5qvyK7I
>
> I suspect it is not too much effort to add DMD's -profile and -profile=gc to LDC, but noone has done it yet.
>
> Another thing that is relatively easy to add to LDC: https://llvm.org/docs/XRay.html

Apart from profiling based on compiler instrumentation, don't forget that LDC uses the standard object file formats/runtime libraries for the various platforms, so all the usual profiling tools like perf, VTune, Valgrind, etc. work just fine.

I would usually start with one of the latter for general-purpose optimization work.

 — David
December 24
On Saturday, 23 December 2017 at 12:23:33 UTC, Johan Engelen wrote:
> On Friday, 22 December 2017 at 09:52:26 UTC, Chris Katko wrote:
>> DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :)
>
> Fine grained PGO profiling:
> -fprofile-instr-generate
> http://johanengelen.github.io/ldc/2016/07/15/Profile-Guided-Optimization-with-LDC.html
>
> Function entry/exit profiling:
> -finstrument-functions
> https://github.com/ldc-developers/ldc/issues/1839
> https://www.youtube.com/watch?v=LNav5qvyK7I
>
> I suspect it is not too much effort to add DMD's -profile and -profile=gc to LDC, but noone has done it yet.
>
> Another thing that is relatively easy to add to LDC: https://llvm.org/docs/XRay.html
>
> -Johan

Wow, thanks guys! I didn't realize I'd get so much information so quickly here on the forums. The documentation online for LDC is very sparse and confusing. After spending plenty of attempts, I went out of my way to install DMD just to get profiling because I couldn't figure it out with LDC.

It would probably be really helpful to get a clear Wiki guide for this information LDC. I'll write it myself if necessary once I try your recommendations and test them out.
December 24
On Sunday, 24 December 2017 at 02:48:32 UTC, Chris Katko wrote:
>
> It would probably be really helpful to get a clear Wiki guide for this information LDC. I'll write it myself if necessary once I try your recommendations and test them out.

This would help us out a lot, thanks.

-Johan



December 26
On Friday, 22 December 2017 at 09:52:26 UTC, Chris Katko wrote:
> DMD can use -profile and -profile=gc. But I tried for HOURS to find the equivalent for LDC and came up with only profile-guided optimization--which I don't believe I want. Yet, if we can get PGO... where's the PROFILE itself it's using to make those decisions! :)
>
> Thanks.

Hi Chris,

I think you might be looking for google perftools.
See:
 1. https://github.com/prasunanand/gperftools_d/
 2. https://github.com/gperftools/gperftools

I have been using gperftools_d a lot to profile my code and optimize.It generates really
cool [graphs](https://github.com/prasunanand/gperftools_d/blob/master/examples/profile.pdf).

If you need PGO, you can look here for reference:
https://github.com/prasunanand/faster_lmm_d/blob/master/Makefile#L122

Let me know if this helps or you face any issues using gperftools_d.

Regards,
Prasun