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PATCH: Support FMA in fma

From: "H.J. Lu" <hongjiu dot lu at intel dot com>
To: GNU C Library <libc-alpha at sourceware dot org>
Cc: drepper at redhat dot com
Date: Wed, 29 Jul 2009 09:48:32 -0700
Subject: PATCH: Support FMA in fma
Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>

Hi,

This patch adds FMA support in fma. I added __libc_cpu_features and
__libc_init_cpu_features so that I can use them in libm.  Tested on
AVX emulator.

Thanks.


H.J.
---
2009-07-29  H.J. Lu  <hongjiu.lu@intel.com>

	* math/s_fma.c (FMA): New.
	(__fma): Renamed to ...
	(FMA): This.

	* sysdeps/x86_64/multiarch/Makefile (CFLAGS-init-arch.c): New.
	(libm-sysdep_routines): Add s_fma-c.

	* sysdeps/x86_64/multiarch/init-arch.c (__libc_cpu_features): New.
	(__libc_init_cpu_features): Likewise.

	* sysdeps/x86_64/multiarch/init-arch.h (__libc_cpu_features): New.
	(__libc_init_cpu_features): Likewise.
	(INIT_ARCH): Use __libc_cpu_features and __libc_init_cpu_features
	if NOT_IN_libc is defined.
	(HAS_POPCOUNT): Use __libc_cpu_features.cpuid if NOT_IN_libc is
	defined.
	(HAS_SSE4_2): Likewise.
	(HAS_FMA): New.

	* sysdeps/x86_64/multiarch/Versions: New.
	* sysdeps/x86_64/multiarch/s_fma-c.c: Likewise.
	* sysdeps/x86_64/multiarch/s_fma.c: Likewise.

diff --git a/math/s_fma.c b/math/s_fma.c
index e5ff5a7..407acdd 100644
--- a/math/s_fma.c
+++ b/math/s_fma.c
@@ -1,5 +1,5 @@
 /* Compute x * y + z as ternary operation.
-   Copyright (C) 1997, 2001 Free Software Foundation, Inc.
+   Copyright (C) 1997, 2001, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
@@ -20,8 +20,12 @@
 
 #include <math.h>
 
+#ifndef FMA
+# define FMA __fma
+#endif
+
 double
-__fma (double x, double y, double z)
+FMA (double x, double y, double z)
 {
   return (x * y) + z;
 }
diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index b066402..dad0731 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -1,5 +1,6 @@
 ifeq ($(subdir),csu)
 aux += init-arch
+CFLAGS-init-arch.c += -fno-common
 gen-as-const-headers += ifunc-defines.sym
 endif
 
@@ -14,3 +15,9 @@ CFLAGS-strstr.c += -msse4
 CFLAGS-strcasestr.c += -msse4
 endif
 endif
+
+ifeq ($(subdir),math)
+ifeq (yes,$(config-cflags-avx))
+libm-sysdep_routines += s_fma-c
+endif
+endif
diff --git a/sysdeps/x86_64/multiarch/Versions b/sysdeps/x86_64/multiarch/Versions
new file mode 100644
index 0000000..0d2d71a
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/Versions
@@ -0,0 +1,6 @@
+libc {
+  GLIBC_PRIVATE {
+    # Internal libc interface to libm
+    __libc_init_cpu_features; __libc_cpu_features;
+  }
+}
diff --git a/sysdeps/x86_64/multiarch/init-arch.c b/sysdeps/x86_64/multiarch/init-arch.c
index 35fd19a..365c8ac 100644
--- a/sysdeps/x86_64/multiarch/init-arch.c
+++ b/sysdeps/x86_64/multiarch/init-arch.c
@@ -86,3 +86,6 @@ __init_cpu_features (void)
   else
     __cpu_features.kind = arch_kind_other;
 }
+
+strong_alias (__cpu_features, __libc_cpu_features)
+strong_alias (__init_cpu_features, __libc_init_cpu_features)
diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
index 48a2127..7d49acd 100644
--- a/sysdeps/x86_64/multiarch/init-arch.h
+++ b/sysdeps/x86_64/multiarch/init-arch.h
@@ -45,19 +45,43 @@ extern struct cpu_features
   unsigned int family;
   unsigned int model;
 } __cpu_features attribute_hidden;
+extern struct cpu_features __libc_cpu_features;
 
 
 extern void __init_cpu_features (void) attribute_hidden;
-#define INIT_ARCH()\
+extern void __libc_init_cpu_features (void);
+#ifdef NOT_IN_libc
+# define INIT_ARCH()\
+  do							\
+    if (__libc_cpu_features.kind == arch_kind_unknown)	\
+      __libc_init_cpu_features ();			\
+  while (0)
+#else
+# define INIT_ARCH()\
   do							\
     if (__cpu_features.kind == arch_kind_unknown)	\
       __init_cpu_features ();				\
   while (0)
+#endif
 
 /* Following are the feature tests used throughout libc.  */
 
-#define HAS_POPCOUNT \
+#ifdef NOT_IN_libc
+# define HAS_POPCOUNT \
+  ((__libc_cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 23)) != 0)
+
+# define HAS_SSE4_2 \
+  ((__libc_cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 20)) != 0)
+
+# define HAS_FMA \
+  ((__libc_cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 12)) != 0)
+#else
+# define HAS_POPCOUNT \
   ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 23)) != 0)
 
-#define HAS_SSE4_2 \
+# define HAS_SSE4_2 \
   ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 20)) != 0)
+
+# define HAS_FMA \
+  ((__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx & (1 << 12)) != 0)
+#endif
diff --git a/sysdeps/x86_64/multiarch/s_fma-c.c b/sysdeps/x86_64/multiarch/s_fma-c.c
new file mode 100644
index 0000000..68837a5
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/s_fma-c.c
@@ -0,0 +1,32 @@
+/* FMA version of fma
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   Contributed by Intel Corporation.
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <config.h>
+
+#ifdef HAVE_AVX_SUPPORT
+
+double
+__fma_fma (double x, double y, double z)
+{
+  asm ("vfmadd213sd %3, %2, %0" : "=x" (x) : "0" (x), "x" (y), "xm" (z));
+  return x;
+}
+
+#endif
diff --git a/sysdeps/x86_64/multiarch/s_fma.c b/sysdeps/x86_64/multiarch/s_fma.c
new file mode 100644
index 0000000..205bb1c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/s_fma.c
@@ -0,0 +1,14 @@
+#include <config.h>
+
+#ifdef HAVE_AVX_SUPPORT
+# include "init-arch.h"
+# define FMA __fma_sse2
+
+extern double __fma (double, double, double);
+extern double __fma_fma (double, double, double);
+extern double __fma_sse2 (double, double, double);
+
+libc_ifunc (__fma, HAS_FMA ? __fma_fma : __fma_sse2);
+#endif
+
+#include <math/s_fma.c>

Follow-Ups:
- Re: PATCH: Support FMA in fma
  - From: Agner Fog

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