http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59262
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |WONTFIX --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- More specifically we cannot inline across changes of -ffast-math as that would generate wrong-code. Thus the non-fast-math 'sum' cannot be inlined into a fast-math annotated function. Which then of course defeats vectorization. Generally I'd advise against using the optimize attribute.