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.

8 files changed, 49 insertions, 72 deletions

diff --git a/sysdeps/i386/fpu/e_log2f.S b/sysdeps/i386/fpu/e_log2f.S
deleted file mode 100644
index 344eeb495e..0000000000
--- a/sysdeps/i386/fpu/e_log2f.S
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * Written by J.T. Conklin <jtc@netbsd.org>.
- * Adapted for use as log2 by Ulrich Drepper <drepper@cygnus.com>.
- * Public domain.
- *
- * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
- */
-
-#include <machine/asm.h>
-
-	.section .rodata.cst8,"aM",@progbits,8
-
-	.p2align 3
-	.type one,@object
-one:	.double 1.0
-	ASM_SIZE_DIRECTIVE(one)
-	/* It is not important that this constant is precise.  It is only
-	   a value which is known to be on the safe side for using the
-	   fyl2xp1 instruction.  */
-	.type limit,@object
-limit:	.double 0.29
-	ASM_SIZE_DIRECTIVE(limit)
-
-
-#ifdef PIC
-# define MO(op) op##@GOTOFF(%edx)
-#else
-# define MO(op) op
-#endif
-
-	.text
-ENTRY(__ieee754_log2f)
-#ifdef PIC
-	LOAD_PIC_REG (dx)
-#endif
-	fldl	MO(one)
-	flds	4(%esp)		// x : 1
-	fxam
-	fnstsw
-	fld	%st		// x : x : 1
-	sahf
-	jc	3f		// in case x is NaN or ħInf
-4:	fsub	%st(2), %st	// x-1 : x : 1
-	fld	%st		// x-1 : x-1 : x : 1
-	fabs			// |x-1| : x-1 : x : 1
-	fcompl	MO(limit)	// x-1 : x : 1
-	fnstsw			// x-1 : x : 1
-	andb	$0x45, %ah
-	jz	2f
-	fxam
-	fnstsw
-	andb	$0x45, %ah
-	cmpb	$0x40, %ah
-	jne	5f
-	fabs			// log2(1) is +0 in all rounding modes.
-5:	fstp	%st(1)		// x-1 : 1
-	fyl2xp1			// log(x)
-	ret
-
-2:	fstp	%st(0)		// x : 1
-	fyl2x			// log(x)
-	ret
-
-3:	jp	4b		// in case x is ħInf
-	fstp	%st(1)
-	fstp	%st(1)
-	ret
-END (__ieee754_log2f)
-strong_alias (__ieee754_log2f, __log2f_finite)
diff --git a/sysdeps/i386/fpu/e_log2f_data.c b/sysdeps/i386/fpu/e_log2f_data.c
deleted file mode 100644
index 1cc8931700..0000000000
--- a/sysdeps/i386/fpu/e_log2f_data.c
+++ /dev/null
@@ -1 +0,0 @@
-/* Not needed.  */
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index ba9b9ec00f..64cac565f2 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -2300,8 +2300,10 @@ ldouble: 3
 
 Function: "log2":
 double: 1
+float: 1
 float128: 2
 idouble: 1
+ifloat: 1
 ifloat128: 2
 ildouble: 1
 ldouble: 1
diff --git a/sysdeps/i386/fpu/w_log2f.c b/sysdeps/i386/fpu/w_log2f.c
deleted file mode 100644
index 3f5c71cec2..0000000000
--- a/sysdeps/i386/fpu/w_log2f.c
+++ /dev/null
@@ -1 +0,0 @@
-#include <sysdeps/../math/w_log2f.c>
diff --git a/sysdeps/i386/i686/fpu/multiarch/Makefile b/sysdeps/i386/i686/fpu/multiarch/Makefile
index ee4c3f39e7..eee3b8b1fd 100644
--- a/sysdeps/i386/i686/fpu/multiarch/Makefile
+++ b/sysdeps/i386/i686/fpu/multiarch/Makefile
@@ -1,8 +1,9 @@
 ifeq ($(subdir),math)
-libm-sysdep_routines += e_exp2f-sse2 e_expf-sse2 e_logf-sse2 \
+libm-sysdep_routines += e_exp2f-sse2 e_expf-sse2 e_logf-sse2 e_log2f-sse2 \
 			s_sinf-sse2 s_cosf-sse2 s_sincosf-sse2
 
 CFLAGS-e_exp2f-sse2.c = -msse2 -mfpmath=sse
 CFLAGS-e_expf-sse2.c = -msse2 -mfpmath=sse
+CFLAGS-e_log2f-sse2.c = -msse2 -mfpmath=sse
 CFLAGS-e_logf-sse2.c = -msse2 -mfpmath=sse
 endif
diff --git a/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c b/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c
new file mode 100644
index 0000000000..a9ed25e399
--- /dev/null
+++ b/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c
@@ -0,0 +1,3 @@
+#define __log2f __log2f_sse2
+
+#include <sysdeps/ieee754/flt-32/e_log2f.c>
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>
diff --git a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
index c86294b778..b5d74df580 100644
--- a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
+++ b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
@@ -2300,8 +2300,10 @@ ldouble: 3
 
 Function: "log2":
 double: 1
+float: 1
 float128: 2
 idouble: 1
+ifloat: 1
 ifloat128: 2
 ildouble: 1
 ldouble: 1