http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53113
--- Comment #20 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to David Kredba from comment #17) > I can't bootstrap 4.9.0 snapshots without patch attached. My machine is > Core2 Quad where are not any avx instructions available. All is compiled > from sources (Gentoo) but libitm x86_avx.lo crashes bootstrap. -march=native > is by gcc translated to core2 what is correct. > The problem is -mno-avx is added by hand. GCC won't use generate AVX instructions with -march=native only if your machine supports AVX. x86_avx.cc is compiled with -mavx on purpose. libitm checks if AVX is supported at run-time and uses x86_avx if AVX is supported. -mno-avx shouldn't added by hand to bootstrap GCC. I think we should close this bug as WONTFIX.
