https://gcc.gnu.org/bugzilla/show_bug.cgi?id=27855
Aldy Hernandez <aldyh at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |aldyh at gcc dot gnu.org --- Comment #54 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- Results from comparing trunk and gcc-4_6-branch on (average of 7 runs): Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz 4.6.x -O2 -ffast-math -msse4.1 -DTYPE=double -fno-tree-reassoc atlasmm 60 1000 0.100 5415.4 -O2 -ffast-math -msse4.1 -DTYPE=double atlasmm 60 1000 0.082 4797.4 Performance penalty: 12.9% trunk: -O2 -ffast-math -msse4.1 -DTYPE=double -fno-tree-reassoc atlasmm 60 1000 0.105 5217.0 -O2 -ffast-math -msse4.1 -DTYPE=double atlasmm 60 1000 0.108 4773.0 Performance change: 9.3% It looks like the penalty for using fno-tree-reassoc now is even less than it was in 4.6.x. The original report was for a 30% drop. Has this been fixed, or am I missing something? (different flags for my 4.6 run? Is the 4.6 branch not a suitable representation of the 4.6.2 compiler against which this bug was originally filed against?)