http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47312
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-02 15:30:51 UTC --- (In reply to comment #2) > One possibility would be to only fold __builtin_fma* into FMA_EXPR after IPA > passes. Expanding FMA_EXPR as __builtin_fma (thus, a libcall) as fallback sounds safe. We probably have similar issues for other builtins (consider the generic vector lowering code for example). Thus, in expr.c only dispatch to expand_ternary_op if there is an optab available, else emit a libcall. "Folding" back to __builtin_fma* sounds ugly.