From: Ulrich Drepper <drepper@gmail.com>
Date: Tue, 18 Oct 2011 03:16:34 +0000 (-0400)
Subject: Small optimization of generic exp2
X-Git-Tag: glibc-2.15~213
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=99ce7b04edf17821a6abd19844f10e8c1cd3c724;p=platform%2Fupstream%2Fglibc.git

Small optimization of generic exp2
---

diff --git a/ChangeLog b/ChangeLog
index c47826c..ad7db01 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2011-10-17  Ulrich Drepper  <drepper@gmail.com>
 
+	* sysdeps/ieee754/dbl-64/e_exp2.c (__ieee754_exp2): Small optimization.
+
 	* sysdeps/ieee754/dbl-64/wordsize-64/s_frexp.c: New file.
 
 	* sysdeps/x86_64/fpu/math_private.h: Relax asm requirements for
diff --git a/sysdeps/ieee754/dbl-64/e_exp2.c b/sysdeps/ieee754/dbl-64/e_exp2.c
index 674cdb0..c973f35 100644
--- a/sysdeps/ieee754/dbl-64/e_exp2.c
+++ b/sysdeps/ieee754/dbl-64/e_exp2.c
@@ -53,8 +53,19 @@ __ieee754_exp2 (double x)
   static const double lomark = (double) (DBL_MIN_EXP - DBL_MANT_DIG - 1);
 
   /* Check for usual case.  */
-  if (isless (x, himark) && isgreaterequal (x, lomark))
+  if (__builtin_expect (isless (x, himark), 1))
     {
+      /* Exceptional cases:  */
+      if (__builtin_expect (! isgreaterequal (x, lomark), 0))
+	{
+	  if (__isinf (x))
+	    /* e^-inf == 0, with no error.  */
+	    return 0;
+	  else
+	    /* Underflow */
+	    return TWOM1000 * TWOM1000;
+	}
+
       static const double THREEp42 = 13194139533312.0;
       int tval, unsafe;
       double rx, x22, result;
@@ -120,16 +131,6 @@ __ieee754_exp2 (double x)
       else
 	return result * scale_u.d;
     }
-  /* Exceptional cases:  */
-  else if (isless (x, himark))
-    {
-      if (__isinf (x))
-	/* e^-inf == 0, with no error.  */
-	return 0;
-      else
-	/* Underflow */
-	return TWOM1000 * TWOM1000;
-    }
   else
     /* Return x, if x is a NaN or Inf; or overflow, otherwise.  */
     return TWO1023*x;