x86-64: Add sincosf with vector FMA

Since the x86-64 assembly version of sincosf is higly optimized with
vector instructions, there isn't much room for improvement.  However
s_sincosf.c written in C with vector math and intrinsics can be
optimized by GCC with FMA.

On Skylake, bench-sincosf reports performance improvement:

           Assembly       FMA         improvement
max        104.042       101.008         3%
min        9.426         8.586           10%
mean       20.6209       18.2238         13%

	* sysdeps/x86_64/fpu/multiarch/Makefile (libm-sysdep_routines):
	Add s_sincosf-sse2 and s_sincosf-fma.
	(CFLAGS-s_sincosf-fma.c): New.
	* sysdeps/x86_64/fpu/multiarch/s_sincosf-fma.c: New file.
	* sysdeps/x86_64/fpu/multiarch/s_sincosf-sse2.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/s_sincosf.c: Likewise.
	* sysdeps/x86_64/fpu/s_sincosf.S: Don't add alias if
	__sincosf is defined.

1 files changed, 28 insertions, 0 deletions

diff --git a/sysdeps/x86_64/fpu/multiarch/s_sincosf.c b/sysdeps/x86_64/fpu/multiarch/s_sincosf.c
new file mode 100644
index 0000000000..6cb4295558
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/s_sincosf.c
@@ -0,0 +1,28 @@
+/* Multiple versions of sincosf.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <libm-alias-float.h>
+
+extern void __redirect_sincosf (float, float *, float *);
+
+#define SYMBOL_NAME sincosf
+#include "ifunc-fma.h"
+
+libc_ifunc_redirected (__redirect_sincosf, __sincosf, IFUNC_SELECTOR ());
+
+libm_alias_float (__sincos, sincos)