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Loop unrolling bug still present
- From: micis at gmx dot de
- To: gcc at gcc dot gnu dot org
- Date: Tue, 1 Jun 2004 11:43:58 +0200 (MEST)
- Subject: Loop unrolling bug still present
It was stated that in the second prerelease of GCC-3.3.4 from 30 May 2004
the -funroll-loop miscompilation has been fixed.
That is true for the default option set.
However, if you use the options
-O2 -funroll-loops --param max-unrolled-insns=xxx
execution of memcpy-1.c will still fail for all xxx > 192
(I only tested PowerPC target)
On PowerPC (G5) I found that --param max-unrolled-insns=600 results
in about 20% - 30% higher speed in my application (mostly Altivec image