Re: PPC optimisations

[Ralph Schmidt <laire at basis dot owl dot de>]

You wrote:
> >>>>> "Philippe C D Robert" writes:
>
> Philippe> I just have a question regarding gcc on PPC plattforms. As it
> seems the Philippe> compiler doesn't optimise very well compared to eg.
> x86. Since I am not really a Philippe> compiler hacker, could someone
> explain to me what the most 'expensive' Philippe> weaknesses are in this
> respect? And how much differs gcc on PPC from other RISC Philippe> archs
> such as eg. gcc on ALPHA?
>
> I do not think the above statement is true and you need to provide
> more justification as to what you are asking.  Also, are you referring to
> gcc-2.95 or to the development sources.  I also would suggest that you
> look at the numerous PowerPC architecture-specific optimizations which
> have been added to the development sources.
>

Well..i've only done a simple test of the current ppc snapshot Franz Sirl
manages and though it had fixed the bug report i gave some days ago it still
had some weird parts.
After i manage a build for my real host system i'll check how it improves
the ppc 68k emulation(global registers, each instruction downcoded) where
the old gcc2.95.2 missed several optimisation possibilties.
I'm also interested into a better ppc gcc support but my impression was that
the focus isn't really on making the code generation as good as possible but
more on things like 64bit,language/bugs,stdlib and linux support.
Personally i can only contribute cases where the code the compiler generates
could be done better...i'm not able to improve the ppc backend myself for  
experience and time reasons.
So there must be somebody who is listening about ppc optimisation misses and
who's able to add that to the compiler....

Regards
---
Ralph Schmidt,laire@popmail.owl.de(private),NextMail welcome