i386: Replace assembly versions of e_log2f with generic e_log2f.c

This patch replaces i386 assembly versions of e_log2f with generic
e_log2f.c.  For workload-spec2017.wrf, on Nehalem, it improves
performance by:

                           Before            After     Improvement
reciprocal-throughput      92.3845          30.8752       199%
latency                    112.855          54.8645       105%

On Skylake, it improves performance by:

                           Before            After     Improvement
reciprocal-throughput      98.7488          22.7507       334%
latency                    118.01           51.6083       128%

On IvyBridge with --disable-multi-arch, it improves performance by:

                           Before            After     Improvement
reciprocal-throughput      106.635          28.8596       269%
latency                    129.888          56.9187       128%

	* sysdeps/i386/fpu/e_log2f.S: Removed.
	* sysdeps/i386/fpu/e_log2f_data.c: Likewise.
	* sysdeps/i386/fpu/w_log2f.c: Likewise.
	* sysdeps/i386/fpu/libm-test-ulps: Updated for generic e_log2f.c.
	* sysdeps/i386/i686/fpu/multiarch/libm-test-ulps: Likewise.
	* sysdeps/i386/i686/fpu/multiarch/Makefile (libm-sysdep_routines):
	Add e_log2f-sse2.
	(CFLAGS-e_log2f-sse2.c): New.
	* sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c: New file.
	* sysdeps/i386/i686/fpu/multiarch/e_log2f.c: Likewise.

1 files changed, 40 insertions, 0 deletions

diff --git a/sysdeps/i386/i686/fpu/multiarch/e_log2f.c b/sysdeps/i386/i686/fpu/multiarch/e_log2f.c
new file mode 100644
index 0000000000..2c4794932a
--- /dev/null
+++ b/sysdeps/i386/i686/fpu/multiarch/e_log2f.c
@@ -0,0 +1,40 @@
+/* Multiple versions of log2f.
+   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/>.  */
+
+extern float __redirect_log2f (float);
+
+#define SYMBOL_NAME log2f
+#include "ifunc-sse2.h"
+
+libc_ifunc_redirected (__redirect_log2f, __log2f, IFUNC_SELECTOR ());
+
+#ifdef SHARED
+__hidden_ver1 (__log2f_ia32, __GI___log2f, __redirect_log2f)
+  __attribute__ ((visibility ("hidden")));
+
+# include <shlib-compat.h>
+versioned_symbol (libm, __log2f, log2f, GLIBC_2_27);
+#else
+weak_alias (__log2f, log2f)
+#endif
+
+strong_alias (__log2f, __ieee754_log2f)
+strong_alias (__log2f, __log2f_finite)
+
+#define __log2f __log2f_ia32
+#include <sysdeps/ieee754/flt-32/e_log2f.c>