http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42445
--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-01-06 16:34:30 UTC --- (In reply to comment #3) > I know nothing about what the issue is supposed to be here or what is or > is not supposed to be in COLLECT_GCC_OPTIONS or how COLLECT_GCC_OPTIONS is > used. We have several issues: 1. COLLECT_GCC_OPTIONS is used by LTO. 2. GCC driver knows -march=native. 3. Compilers, cc1/cc1plus, ... don't know -march=native. GCC driver translates -march=native to something cc1/cc1plus knows. Since -march=native isn't saved in COLLECT_GCC_OPTIONS, LTO doesn't work with -march=native. If -march=native handling is moved from GCC driver to cc1/cc1plus, this issue can be solved very easily.