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Re: [PATCH] Fix PR37053: Move tweaks of commutative precedence to target hook


On Fri, 2009-06-26 at 18:15 +0400, Maxim Kuvyrkov wrote:
> The attached patch fixes PR37053 
> (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37053#c5).
> 
> The problem was introduced by patch for PR28690 
> (http://gcc.gnu.org/ml/gcc-patches/2006-12/msg00268.html, rtlanal.c 
> hunk); this hunk causes ICE on m68k (and, possibly, other) architectures.
[snip]
> My first impulse was to remove the pointer tweak; but, well, if PowerPC 
> really benefits from it,


I will say we worked for a long time coming up with the patch we did so
that it didn't affect other arches.  In particular, HJ ran a lot of
performance tests to make sure it didn't degrade performance on x86.
I will also note, that without this patch, SPEC2000 performance degrades
by about 30% across the entire benchmark suite and 500% on galgel on
POWER6, so yeah, we benefit from it. :)


> ..., let's make it a hook.
> 
> The attached patch does just that.  Bootstrapped on x86_64-linux-gnu and 
> cross-build to powerpc-linux-gnu (with no new warnings in logs); ok to 
> apply?

I'll let others comment on whether they want a target hook solution or not.
If they don't, I'm willing to work with you to come up with something that
works for both of us.

In the mean time, I have asked Luis to test your patch on POWER6 to ensure
there are no performance degradations.  It doesn't look like there should
be, but...


Peter




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