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Re: [PATCH] Fix some of the PR33870 fix fallout
On Sun, 28 Oct 2007, H.J. Lu wrote:
> On Sun, Oct 28, 2007 at 07:31:57PM +0100, Richard Guenther wrote:
> >
> > The PR33870 fix caused quite some compile-time regressions. While
> > this unfortunately cannot be avoided completely (at least without
> > changing what we partition, and thus potentially causing runtime
> > performance regressions), the following patch makes us re-consider
> > a few less vars.
> >
> > It also fixes one potential problem, if we don't have flow-sensitive
> > alias info, we shouldn't try to prune based on the offset/size from
> > the referece as we really don't know what the pointer points to.
> >
> > Bootstrapped on x86_64-unknown-linux-gnu, testing in progress. I'll
> > apply this to make our internal testers pick this up tonight.
> >
>
> I saw 11% drop in 200.sixtrack performance on Core 2 Duo 64bit
> between revision 129621 and revision 129678. Is that related to
> the fix for PR 33870?
This might be the case only if the VOPs were wrong before ;) What I
see on some testcases is that we have before the patch
# VUSE <MPT.4_3>
tmp_4 = (*s_4)[i_2];
while after the patch we have
# VUSE <MPT.4_3, SFT.2_1, SFT.3_2>
tmp_4 = (*s_4)[i_2];
because those are not in MPT.4 but are aliased by the load.
Richard.