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Re: Predictive commoning miscompiles 482.sphinx3 in SPEC CPU 2006

On 6/1/07, H. J. Lu <hjl@lucon.org> wrote: 
On Fri, Jun 01, 2007 at 09:37:54AM -0700, H. J. Lu wrote:
> The predictive commoning patch:
>
> http://gcc.gnu.org/ml/gcc-patches/2007-05/msg01061.html
>
> miscompiles 482.sphinx3 in SPEC CPU 2006 with -O2 -ffast-math on
> Linux/x86-64.  Zdenek, do you have any ideas?
>

Something is wrong. Predictive commoning is supposed to be turned
on at -O3. But it definitely afffects -O2. Why?


Because the patch had other effects like adding a DCE after Copyprop
in the loop optimizer section.

This actually speed up a couple of benchmarks in SPEC 2k too (mgrid
and apsi comes to mind).

Thanks,
Andrew Pinski

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