[Bug tree-optimization/49365] 436.cactusADM performance regression

[changpeng.fang at amd dot com]

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