Optimize exp

Add __exp*_finite optimizations and rewrite some wrappers.

2 files changed, 42 insertions, 55 deletions

diff --git a/sysdeps/ieee754/flt-32/e_expf.c b/sysdeps/ieee754/flt-32/e_expf.c
index b9cd53c033..872d34bc5b 100644
--- a/sysdeps/ieee754/flt-32/e_expf.c
+++ b/sysdeps/ieee754/flt-32/e_expf.c
@@ -1,5 +1,5 @@
 /* Single-precision floating point e^x.
-   Copyright (C) 1997, 1998, 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 1997, 1998, 2005, 2006, 2011 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Geoffrey Keating <geoffk@ozemail.com.au>
 
@@ -33,8 +33,8 @@
    Then e^x is approximated as
 
    e^x = 2^n ( e^(t/512 + delta[t])
-               + ( e^(t/512 + delta[t])
-                   * ( p(x + delta[t] + n * ln(2)) - delta ) ) )
+	       + ( e^(t/512 + delta[t])
+		   * ( p(x + delta[t] + n * ln(2)) - delta ) ) )
 
    where
    - p(x) is a polynomial approximating e(x)-1;
@@ -138,3 +138,4 @@ __ieee754_expf (float x)
     /* Return x, if x is a NaN or Inf; or overflow, otherwise.  */
     return TWO127*x;
 }
+strong_alias (__ieee754_expf, __expf_finite)
diff --git a/sysdeps/ieee754/flt-32/w_expf.c b/sysdeps/ieee754/flt-32/w_expf.c
index 83b268f570..151c584547 100644
--- a/sysdeps/ieee754/flt-32/w_expf.c
+++ b/sysdeps/ieee754/flt-32/w_expf.c
@@ -1,60 +1,46 @@
-/* w_expf.c -- float version of w_exp.c.
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- */
-
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice 
- * is preserved.
- * ====================================================
- */
-
-#if defined(LIBM_SCCS) && !defined(lint)
-static char rcsid[] = "$NetBSD: w_expf.c,v 1.3 1995/05/10 20:48:53 jtc Exp $";
-#endif
-
-/* 
- * wrapper expf(x)
- */
-
-#include "math.h"
-#include "math_private.h"
-
-#ifdef __STDC__
+/* 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 <math.h>
+#include <math_private.h>
+
 static const float
-#else
-static float
-#endif
 o_threshold=  8.8722831726e+01,  /* 0x42b17217 */
 u_threshold= -1.0397208405e+02;  /* 0xc2cff1b5 */
 
-#ifdef __STDC__
-	float __expf(float x)		/* wrapper expf */
-#else
-	float __expf(x)			/* wrapper expf */
-	float x;
-#endif
+
+/* wrapper expf */
+float
+__expf (float x)
 {
-#ifdef _IEEE_LIBM
-	return __ieee754_expf(x);
-#else
-	float z;
-	z = __ieee754_expf(x);
-	if(_LIB_VERSION == _IEEE_) return z;
-	if(__finitef(x)) {
-	    if(x>o_threshold)
-	        /* exp overflow */
-	        return (float)__kernel_standard((double)x,(double)x,106);
-	    else if(x<u_threshold)
-	        /* exp underflow */
-	        return (float)__kernel_standard((double)x,(double)x,107);
-	} 
-	return z;
-#endif
+  if (__builtin_expect (x > o_threshold, 0))
+    {
+      if (_LIB_VERSION != _IEEE_)
+	return __kernel_standard_f (x, x, 106);
+    }
+  else if (__builtin_expect (x < u_threshold, 0))
+    {
+      if (_LIB_VERSION != _IEEE_)
+	return __kernel_standard_f (x, x, 107);
+    }
+
+  return __ieee754_expf (x);
 }
 hidden_def (__expf)
 weak_alias (__expf, expf)