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[Bug tree-optimization/49365] 436.cactusADM performance regression
- From: "changpeng.fang at amd dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 14 Jun 2011 22:23:08 +0000
- Subject: [Bug tree-optimization/49365] 436.cactusADM performance regression
- Auto-submitted: auto-generated
- References: <bug-49365-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49365
--- Comment #5 from Changpeng Fang <changpeng.fang at amd dot com> 2011-06-14 22:22:11 UTC ---
It seems there is a prefetch generation bug on Bulldozer.
With -O3 -ffast-math -funroll-loops -fpeel-loops -march=bdver1
-fprefetch-loop-arrays, I got a normal timing of 795s.
However, when "--param min-insn-to-prefetch-ratio=9" is added, the timing
becomes 2853s.
This may be a different bug, in the opposite direction to amdfam10
I also want to mention here that software prefetching was actually enabled
at -O3 and higher for Bulldozer, when Honza cleaned up the code in i386.c
http://gcc.gnu.org/ml/gcc-patches/2011-05/msg00573.html