http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56253
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2013-02-08 13:30:14 UTC --- (In reply to comment #3) > (In reply to comment #1) > > > not sure why we use builtins for these basic operations... > > Because they have to be emitted also for non-SSE math. > > From config/i386/sse.md: > > ;; The standard names for fma is only available with SSE math enabled. > (define_expand "fma<mode>4" > [(set (match_operand:FMAMODE 0 "register_operand") > (fma:FMAMODE > (match_operand:FMAMODE 1 "nonimmediate_operand") > (match_operand:FMAMODE 2 "nonimmediate_operand") > (match_operand:FMAMODE 3 "nonimmediate_operand")))] > "(TARGET_FMA || TARGET_FMA4) && TARGET_SSE_MATH") > > ... > > ;; The builtin for intrinsics is not constrained by SSE math enabled. > > (define_expand "fma4i_fmadd_<mode>" > [(set (match_operand:FMAMODE 0 "register_operand") > (fma:FMAMODE > (match_operand:FMAMODE 1 "nonimmediate_operand") > (match_operand:FMAMODE 2 "nonimmediate_operand") > (match_operand:FMAMODE 3 "nonimmediate_operand")))] > "TARGET_FMA || TARGET_FMA4") Ah, of course ... That leaves the option of folding in targetm.fold_builtin (when the standard names are available, of course).
