Hi all,
  I've written an article about how I implemented profile-guided optimization (PGO) of virtual calls to direct calls (a micro-micro-optimization, expected performance gain of just a few percent if any!). I hope it's interesting for those of you who like to read about compiler internals.

https://johanengelen.github.io/ldc/2016/04/13/PGO-in-LDC-virtual-calls.html

It's my first programming article, please be gentle with your comments :-)

cheers,
  Johan

On 04/13/2016 07:34 AM, Johan Engelen wrote:
> Hi all,
>    I've written an article about how I implemented profile-guided
> optimization (PGO) of virtual calls to direct calls (a
> micro-micro-optimization, expected performance gain of just a few
> percent if any!). I hope it's interesting for those of you who like to
> read about compiler internals.
>
> https://johanengelen.github.io/ldc/2016/04/13/PGO-in-LDC-virtual-calls.html
>
> It's my first programming article, please be gentle with your comments :-)
>
> cheers,
>    Johan

Noice.

https://twitter.com/D_Programming/status/720236648034877440

https://www.facebook.com/dlang.org/posts/1275322695814742

https://www.reddit.com/r/programming/comments/4elfok/profile_guided_optimization_optimizing_ds_virtual/

http://hackerne.ws


Andrei

On Wednesday, 13 April 2016 at 13:08:30 UTC, Andrei Alexandrescu wrote:
>
> Noice.
>
> https://twitter.com/D_Programming/status/720236648034877440
>
> https://www.facebook.com/dlang.org/posts/1275322695814742
>
> https://www.reddit.com/r/programming/comments/4elfok/profile_guided_optimization_optimizing_ds_virtual/
>
> http://hackerne.ws

Thanks for posting these!

-Johan

On Wednesday, 13 April 2016 at 11:34:26 UTC, Johan Engelen wrote:
> Hi all,
>   I've written an article about how I implemented profile-guided optimization (PGO) of virtual calls to direct calls (a micro-micro-optimization, expected performance gain of just a few percent if any!).

I've updated the article with performance measurements of just the D code of LDC: the improvement with PGO is about 7% !

On Thursday, 14 April 2016 at 08:20:53 UTC, Johan Engelen wrote:
> On Wednesday, 13 April 2016 at 13:08:30 UTC, Andrei Alexandrescu wrote:
>>
>> Noice.
>>
>> https://twitter.com/D_Programming/status/720236648034877440
>>
>> https://www.facebook.com/dlang.org/posts/1275322695814742
>>
>> https://www.reddit.com/r/programming/comments/4elfok/profile_guided_optimization_optimizing_ds_virtual/
>>
>> http://hackerne.ws
>
> Thanks for posting these!
>
> -Johan

Found this, too:
http://llvmweekly.org/issue/120

Am Fri, 15 Apr 2016 09:04:21 +0000
schrieb Johan Engelen <j@j.nl>:

> On Wednesday, 13 April 2016 at 11:34:26 UTC, Johan Engelen wrote:
> > Hi all,
> >   I've written an article about how I implemented
> > profile-guided optimization (PGO) of virtual calls to direct
> > calls (a micro-micro-optimization, expected performance gain of
> > just a few percent if any!).
> 
> I've updated the article with performance measurements of just the D code of LDC: the improvement with PGO is about 7% !

Compilers are full of logic that makes some code 0.5% faster. The sum of all these little bits is what makes up an optimizing compiler and if today you still find an optimization that's worth 1 or 2% you have a jackpot!

7% is quite a bit more than any other option like -cpu=native could achieve. If feasible I'd enjoy if ldc2 shipped with a pgo configuration option. If you use the compiler in a lot of edit/compile cycles it will pay off.

-- 
Marco

On Wednesday, 20 April 2016 at 22:10:53 UTC, Marco Leise wrote:
> 
> 7% is quite a bit more than any other option like -cpu=native could achieve. If feasible I'd enjoy if ldc2 shipped with a pgo configuration option. If you use the compiler in a lot of edit/compile cycles it will pay off.

This was the use-case I was optimizing for, and so I will add an option to pass a PGO profile to the CMake script :-)
Note that it is a 7% improvement in the D part of LDC. The optimizer (LLVM, C++) takes most of the time during compilation and so the overall performance increase is smaller.

On Wednesday, 13 April 2016 at 11:34:26 UTC, Johan Engelen wrote:
> Hi all,
>   I've written an article about how I implemented profile-guided optimization (PGO)

I packaged LDC v1.0.0 with PGO for OS X:
https://github.com/JohanEngelen/ldc/releases/tag/v1.0.0-beta1-pgo

All your feedback is very welcome :-)

cheers,
  Johan