http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56253
--- Comment #3 from Uros Bizjak <ubizjak at gmail dot com> 2013-02-08 12:58:49
UTC ---
(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")
