From: Szabolcs Nagy <nsz@port70.net>
Date: Sat, 11 Apr 2015 00:35:07 +0000 (+0000)
Subject: math: fix pow(+-0,-inf) not to raise divbyzero flag
X-Git-Tag: v1.1.9~53
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=cb5c057c87240a9534f8e0d9b7ff2560082f6218;p=oweals%2Fmusl.git

math: fix pow(+-0,-inf) not to raise divbyzero flag

this reverts the commit f29fea00b5bc72d4b8abccba2bb1e312684d1fce
which was based on a bug in C99 and POSIX and did not match IEEE-754
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1515.pdf
---

diff --git a/src/math/pow.c b/src/math/pow.c
index 82f684bd..b66f632d 100644
--- a/src/math/pow.c
+++ b/src/math/pow.c
@@ -143,7 +143,7 @@ double pow(double x, double y)
 				return 1.0;
 			else if (ix >= 0x3ff00000) /* (|x|>1)**+-inf = inf,0 */
 				return hy >= 0 ? y : 0.0;
-			else if ((ix|lx) != 0)     /* (|x|<1)**+-inf = 0,inf if x!=0 */
+			else                       /* (|x|<1)**+-inf = 0,inf */
 				return hy >= 0 ? 0.0 : -y;
 		}
 		if (iy == 0x3ff00000) {    /* y is +-1 */
diff --git a/src/math/powf.c b/src/math/powf.c
index 59baf6f3..427c8965 100644
--- a/src/math/powf.c
+++ b/src/math/powf.c
@@ -90,7 +90,7 @@ float powf(float x, float y)
 			return 1.0f;
 		else if (ix > 0x3f800000)  /* (|x|>1)**+-inf = inf,0 */
 			return hy >= 0 ? y : 0.0f;
-		else if (ix != 0)          /* (|x|<1)**+-inf = 0,inf if x!=0 */
+		else                       /* (|x|<1)**+-inf = 0,inf */
 			return hy >= 0 ? 0.0f: -y;
 	}
 	if (iy == 0x3f800000)    /* y is +-1 */
diff --git a/src/math/powl.c b/src/math/powl.c
index a765706d..5b6da07b 100644
--- a/src/math/powl.c
+++ b/src/math/powl.c
@@ -227,7 +227,7 @@ long double powl(long double x, long double y)
 	if (y <= -LDBL_MAX) {
 		if (x > 1.0 || x < -1.0)
 			return 0.0;
-		if (x != 0.0)
+		if (x != 0.0 || y == -INFINITY)
 			return INFINITY;
 	}
 	if (x >= LDBL_MAX) {