svn commit: r229844 - stable/8/lib/msun/src

[David Schultz]

Author: das
Date: Mon Jan  9 04:58:02 2012
New Revision: 229844
URL: http://svn.freebsd.org/changeset/base/229844

Log:
  MFC r226595:
    Per IEEE754r, pow(1, y) is 1 even if y is NaN, and pow(-1, +-Inf) is 1.

Modified:
  stable/8/lib/msun/src/e_pow.c
  stable/8/lib/msun/src/e_powf.c
Directory Properties:
  stable/8/lib/msun/   (props changed)

Modified: stable/8/lib/msun/src/e_pow.c
==============================================================================
--- stable/8/lib/msun/src/e_pow.c	Mon Jan  9 04:57:59 2012	(r229843)
+++ stable/8/lib/msun/src/e_pow.c	Mon Jan  9 04:58:02 2012	(r229844)
@@ -109,6 +109,9 @@ __ieee754_pow(double x, double y)
     /* y==zero: x**0 = 1 */
 	if((iy|ly)==0) return one; 	
 
+    /* x==1: 1**y = 1, even if y is NaN */
+	if (hx==0x3ff00000 && lx == 0) return one;
+
     /* y!=zero: result is NaN if either arg is NaN */
 	if(ix > 0x7ff00000 || ((ix==0x7ff00000)&&(lx!=0)) ||
 	   iy > 0x7ff00000 || ((iy==0x7ff00000)&&(ly!=0))) 
@@ -138,7 +141,7 @@ __ieee754_pow(double x, double y)
 	if(ly==0) { 	
 	    if (iy==0x7ff00000) {	/* y is +-inf */
 	        if(((ix-0x3ff00000)|lx)==0)
-		    return  y - y;	/* inf**+-1 is NaN */
+		    return  one;	/* (-1)**+-inf is NaN */
 	        else if (ix >= 0x3ff00000)/* (|x|>1)**+-inf = inf,0 */
 		    return (hy>=0)? y: zero;
 	        else			/* (|x|<1)**-,+inf = inf,0 */

Modified: stable/8/lib/msun/src/e_powf.c
==============================================================================
--- stable/8/lib/msun/src/e_powf.c	Mon Jan  9 04:57:59 2012	(r229843)
+++ stable/8/lib/msun/src/e_powf.c	Mon Jan  9 04:58:02 2012	(r229844)
@@ -67,6 +67,9 @@ __ieee754_powf(float x, float y)
     /* y==zero: x**0 = 1 */
 	if(iy==0) return one;
 
+    /* x==1: 1**y = 1, even if y is NaN */
+	if (hx==0x3f800000) return one;
+
     /* y!=zero: result is NaN if either arg is NaN */
 	if(ix > 0x7f800000 ||
 	   iy > 0x7f800000)
@@ -90,7 +93,7 @@ __ieee754_powf(float x, float y)
     /* special value of y */
 	if (iy==0x7f800000) {	/* y is +-inf */
 	    if (ix==0x3f800000)
-	        return  y - y;	/* inf**+-1 is NaN */
+	        return  one;	/* (-1)**+-inf is NaN */
 	    else if (ix > 0x3f800000)/* (|x|>1)**+-inf = inf,0 */
 	        return (hy>=0)? y: zero;
 	    else			/* (|x|<1)**-,+inf = inf,0 */