From 0ac5ae2335292908f39031b1ea9fe8edce433c0f Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@gmail.com>
Date: Wed, 12 Oct 2011 11:27:51 -0400
Subject: Optimize libm

libm is now somewhat integrated with gcc's -ffinite-math-only option
and lots of the wrapper functions have been optimized.
---
 math/w_log2.c | 49 +++++++++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 16 deletions(-)

(limited to 'math/w_log2.c')

diff --git a/math/w_log2.c b/math/w_log2.c
index 90d2dff5d6..6d420438d4 100644
--- a/math/w_log2.c
+++ b/math/w_log2.c
@@ -1,29 +1,46 @@
-/*
- * wrapper log2(X)
- */
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
 
+   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 <fenv.h>
 #include <math.h>
 #include <math_private.h>
 
+
+/* wrapper log2(x) */
 double
-__log2 (double x)	/* wrapper log2 */
+__log2 (double x)
 {
-#ifdef _IEEE_LIBM
-  return __ieee754_log2 (x);
-#else
-  double z;
-  z = __ieee754_log2 (x);
-  if (_LIB_VERSION == _IEEE_ || __isnan (x)) return z;
-  if (x <= 0.0)
+  if (__builtin_expect (x <= 0.0, 0) && _LIB_VERSION != _IEEE_)
     {
       if (x == 0.0)
-	return __kernel_standard (x, x, 48); /* log2 (0) */
+	{
+	  feraiseexcept (FE_DIVBYZERO);
+	  return __kernel_standard (x, x, 48); /* log2(0) */
+	}
       else
-	return __kernel_standard (x, x, 49); /* log2 (x < 0) */
+	{
+	  feraiseexcept (FE_INVALID);
+	  return __kernel_standard (x, x, 49); /* log2(x<0) */
+	}
     }
-  else
-    return z;
-#endif
+
+  return  __ieee754_log2 (x);
 }
 weak_alias (__log2, log2)
 #ifdef NO_LONG_DOUBLE
-- 
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