[Bug optimization/11707] [3.4 Regression] [new unroller] constants not propagated in unrolled loop iterations with a conditional

["rguenth at tat dot physik dot uni-tuebingen dot de" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11707



------- Additional Comments From rguenth at tat dot physik dot uni-tuebingen dot de  2003-09-29 16:01 -------
Subject: Re:  [3.4 Regression] [new unroller] constants
 not propagated in unrolled loop iterations with a conditional

On 29 Sep 2003, rakdver at gcc dot gnu dot org wrote:

> ------- Additional Comments From rakdver at gcc dot gnu dot org  2003-09-29 12:31 -------
> This is just a pass ordering problem. Copy propagation in jump bypassing
> is being run between old and new loop unroller; so it acts on already unrolled
> loop with -fold-unroll-loops, but is not able to do anything senseful
> with -funroll-loops.
>
> On rtlopt-branch I have moved unroller before jump bypassing, this is why it
> does not reproduce there.
>
> On tree-ssa constant propagation is able to detect that a*=a is no-op in this
> case. Cool.
>
> Anyway, the attached patch fixes the problem.  I believe moving jump bypassing
> after unroller should not harm anything.

The attached patch fixes the regression to the 3.3 behavior which is still
a regression from 2.95.3 (unnecessary imull).

Richard.

--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/