http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49365
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-06-10 15:36:49 UTC --- I'm trying to get my hands on it. Most code differences betweeen good and bad rev. appear in loop array prefetching. Before aprefetch dumps differ only for datestamp.c, PUGH/SetupPGV.c and regex.c. I'm trying binaries with -fno-prefetch-loop-arrays now (well, on Monday that is). Prefetching uses tree_num_loop_insns which uses estimate_num_insns. Prefetching is enabled by default for barcelona (but also for K8 where I don't see this issue). So my bet is on prefetching costs getting confused and need adjustment.
