http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59035
--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- If -ffp-contract=off is set for any object (whether explicitly, or implicitly by an option such as -std=c99), the safe option for LTO would be to set -ffp-contract=off at link time as well.