https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78379
--- Comment #16 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> --- (In reply to Thomas Koenig from comment #15) > OMG, the world of processors is more complicated than I thought. > So, these rather modern AMD chips support AVX, but suck at it. > > Two questions: > > - Can you check if -mfma3 and/or -mfma4 make any difference? > > - If you start any program compiled with -g under the debugger, break > anywhere (for example at the beginning of the main program) > and do a "p __cpu_model", what do you get? The A10-5800K p __cpu_model $1 = {__cpu_vendor = 2, __cpu_type = 5, __cpu_subtype = 8, __cpu_features = {883711}} The A8: p __cpu_model $2 = {__cpu_vendor = 2, __cpu_type = 9, __cpu_subtype = 0, __cpu_features = {855039}} The A6: p __cpu_model $1 = {__cpu_vendor = 2, __cpu_type = 0, __cpu_subtype = 0, __cpu_features = {2111}} neither -mfma nor -mfma4 help