http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53967
--- Comment #14 from bfriesen at simple dot dallas.tx.us 2012-07-18 14:28:04 UTC --- With -m64 -mtune=generic -march=x86-64 -mfpmath=sse -O2 -funroll-loops -fschedule-insns I see a whole-program performance jump from 0.047 iter/s to 0.156 iter/s (331% boost). That is huge! Given the fundamental properties of this algorithm (the image processing algorithm most often recommended to be moved to a GPU) the world would be a better place if this performance was the normal case. With -m64 -mtune=generic -march=x86-64 -mfpmath=sse -O2 -fschedule-insns I see 0.101 iter/s These must not be included in -O3 since -m64 -mtune=generic -march=x86-64 -mfpmath=sse -O3 produces only 0.048 iter/s
