Re: loop optimization in gcc

[sandeep soni <saintiwara at gmail dot com>]

On Wed, Oct 14, 2009 at 9:02 PM, Tobias Grosser
<grosser@fim.uni-passau.de> wrote:
> On Wed, 2009-10-14 at 20:12 +0530, sandeep soni wrote:
>> > Hi,
>> >
>> > you also might want to take a look at the Graphite project.
>> > http://gcc.gnu.org/wiki/Graphite where we do loop optimizations and
>> > automatic parallelization based on the polytop model. If you need any
>> > help feel free to ask.
>> >
>> > Tobias
>> >
>> >
>>
>> Hi,
>>
>> This seems to be quite interesting and challenging.Moreover,it is very
>> close to what we are trying to achieve as well (on a small scale that
>> is).I have started preliminary reading on the polytope model and the
>> working of GRAPHITE. I will ask you if i face any doubts.It would be
>> nice to contribute to this project.
>>
>>
>> For the starters, can you tell me if GRAPHITE also does source to
>> source transformations or otherwise to optimize??Coz i had read
>> somewhere else that the polyhedral model used source to source
>> transformations.
>
> Hi,
>
> you are right. There are several polytope frameworks that work on the
> source code level (LooPo, Cloog/Clan from Cedric Bastoul), however
> Graphite works on the intermediate level tree-ssa in gcc. Therefore we
> can not do any source to source transformations.
> The idea is to not be limited to specific input languages or special
> formatting of the code, but to be able to use the powerful analysis in
> the gcc middle end.
> This allows us to work on any input language and to detect loops that do
> not even look like a loop in the input program (goto-loops). Using the
> powerful scalar evolution framework in gcc Graphite also handles loops
> that do not look like affine linear loops.
> This is a powerful approach in its earlier stages. Basic loops and
> simple code transformations already work, but there is still a lot left
> to be done.
>
> Tobi
>
>

Hi,

 Sounds absolutely convincing to me. I am too keen to contribute in
this in any way possible.I will first try to understand how it works
totally .Would you mind me pressing on with some of issues in the near
future? I am afraid though that they might be a bit more theoretical
to begin with.


-- 
cheers
sandy