Another follow-on bug similar to bug 21485. The profiled optimizer on both
3.4.3 and 4.0.0 makes code worse than without it. Run times go up by 50% or
more.
Relevant flags are: -static -O3 -march=athlon-xp -fomit-frame-pointer
This runs a fixed number of iterations; time from the command line to compare.
This is probably an interesting bug on its own, or at least I hope so. However,
what I originally discovered with the real BYTEmark code was that 3.4.3's
profiled optimizer made the code better, but 4.0.0's made it worse. Somehow, in
the process of combining things into one file and removing redundant code,
3.4.3's profiled optimizer started pessimizing the code as well. Let me know if
I should attempt to reproduce that behavior again (though I might not be able to
come up with the single-preprocessed-file testcase for that).
--
Summary: BYTEmark bitmap test: Regression with Profiled
Optimization
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jbucata at tulsaconnect dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC host triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21527
