http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54966
--- Comment #11 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-11-12 13:19:42 UTC --- much better with gcc version 4.8.0 20121112 (experimental) [trunk revision 193427] (GCC) but for "size 6. v1" with lto [innocent@vinavx0 bugs48]$ c++ -Ofast smatrix.ii -march=native ; taskset -c 2 ./a.out size 5. v1: time in cycles 6925.32 size 5. v2: time in cycles 2123.49 size 5. v3: time in cycles 1067.43 size 6. v1: time in cycles 31216.7 size 6. v2: time in cycles 3521.98 size 6. v3: time in cycles 2523.74 [innocent@vinavx0 bugs48]$ c++ -Ofast smatrix.ii -march=native -flto; taskset -c 2 ./a.out size 5. v1: time in cycles 6367.09 size 5. v2: time in cycles 1181.97 size 5. v3: time in cycles 1194.82 size 6. v1: time in cycles 34811.5 size 6. v2: time in cycles 1909.71 size 6. v3: time in cycles 1803.48 of course inlining also the case " v1" would be even better !(the code is equivalent to v2 and v3) I've some other more complex functions where inline is "different" than 4.7.2 but not necessarily better will try to cut a test case
