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[Bug optimization/11707] [3.4 Regression] [new unroller] constants not propagated in unrolled loop iterations with a conditional
- From: "rakdver at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 29 Sep 2003 12:31:21 -0000
- Subject: [Bug optimization/11707] [3.4 Regression] [new unroller] constants not propagated in unrolled loop iterations with a conditional
- References: <20030729133436.11707.rguenth@tat.physik.uni-tuebingen.de>
- Reply-to: 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 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.