[Bug optimization/11319] [3.3/3.4 regression] loop miscompiled on ppc32

["wilson at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11319



------- Additional Comments From wilson at gcc dot gnu dot org  2003-09-07 05:35 -------
The bug has been fixed by the alias.c patch.  However, there were questions
raised about the effect of the patch on the performance of gcc compiled code.  I
have left the bug report open for now as a reminder to look into this issue.

I have checked in a patch to fix the loop_regs_update !INSN_P problem I
mentioned earlier.
  http://gcc.gnu.org/ml/gcc-patches/2003-09/msg00397.html

I have done SPEC testing on a Pentium4 system running GNU/Linux.  I used -O2
-march=pentium4 as the gcc optimization options.  I see no significant effect on
the performance for those benchmarks that I could get running.  I do see a
noticable drop in 301.apsi performance after the first loop_regs_update patch
went in, but it went back up after the alias.c patch went in, so the problem
seems to have corrected itself.

PowerPC performance tests are pending.



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