[Mono-dev] Current status of global regalloc (regalloc2.c)

[Sergei Dyshel]

Hi Zoltan,
I've tried LLVM in the past and even remember making it work on PowerPC (to
some extent). Of course it gives much better performance but it's too
heavy-weight back-end for my project and, besides, there are other reasons
why I can't use LLVM.

So I have too stay with 'mini' :-). I've made some tweaks to it but still
its division of vregs to local and global sometimes drastically decreases
code performance by making a lot of redundant moves.

So I started to think that may be global allocator is the only 'cure'. How
many work, do you think, will it take to make it work on PowerPC for simple
scenarios I described?
-- 
Regards,
Sergei Dyshel


On Tue, Sep 14, 2010 at 19:46, Zoltan Varga <vargaz at gmail.com> wrote:

> Hi,
>
>   If you want better performance, I suggest looking at the the llvm
> backend:
>
> http://www.mono-project.com/Mono_LLVM
>
>                    Zoltan
>
> On Tue, Sep 14, 2010 at 3:58 PM, Sergei Dyshel <qyron.private at gmail.com>wrote:
>
>> Hi,
>>
>> What is the current status of this feature? The regalloc2.c file wasn't
>> substantially updated during last couple of years. Some citations from the
>> file's comments section:
>>
>> Focus was on correctness and easy debuggability so *performance is bad*
>>
>>
>> Bad related to what? I've tried both schemes, current vs globalra, on some
>> computationally-intensive kernels and globally-allocated version seems
>> always to run faster, even with x2-x3 speedups in case of floating-point
>> kernels. Is this supposed behavior?
>>
>> Only works on amd64
>>
>>
>> Is this true for now? I'm actually interested in 32-bit x86 and PowerPC
>> back-ends. How much is required to make globalra work for them too? There
>> are relatively few places where globalra is used in 'mini-amd64.c' so it
>> doesn't seem hard to port these changes to 'mini-x86.c'.
>>
>> In my project I only need to execute very simple small computational
>> kernels, with no arguments, no calls to another functions (hence no need to
>> distinguish between callee/caller saved registers), only global static
>> arrays are used?
>>
>> Any answers/comments are greatly appreciated!
>> --
>> Regards,
>> Sergei Dyshel
>>
>> _______________________________________________
>> Mono-devel-list mailing list
>> Mono-devel-list at lists.ximian.com
>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.ximian.com/pipermail/mono-devel-list/attachments/20100914/57c75670/attachment.html