From: Gabriel F. T. Gomes <gftg@linux.vnet.ibm.com>
Date: Fri, 6 Jan 2017 15:05:30 +0000 (-0200)
Subject: ldbl-128: Fix y0 and y1 for -Inf input [BZ #21130]
X-Git-Tag: glibc-2.26~788
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b987917e6aa7ffe2fd74f0b6a989438e6edd0727;p=thirdparty%2Fglibc.git

ldbl-128: Fix y0 and y1 for -Inf input [BZ #21130]

The Bessel functions of the second type (Yn) are not defined for
negative input and should return NAN with the "invalid" exception
raised, in these cases.  However, current code checks for infinity and
return zero, regardless of the sign.  This error is exposed for long
double when linking with -lieee.  Without this flag, the error is not
exposed, because the wrappers for these functions, which use
__kernel_standard functionality, return the correct value.

Tested for powerpc64le.

	[BZ #21130]
	* sysdeps/ieee754/ldbl-128/e_j0l.c (__ieee754_y0l): Return NAN
	with the "invalid" exception raised when x is -Inf.
	* sysdeps/ieee754/ldbl-128/e_j1l.c (__ieee754_y1l): Likewise.
---

diff --git a/ChangeLog b/ChangeLog
index fac0e11c40b..27f41f7ad04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-02-12  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>
+
+	[BZ #21130]
+	* sysdeps/ieee754/ldbl-128/e_j0l.c (__ieee754_y0l): Return NAN
+	with the "invalid" exception raised when x is -Inf.
+	* sysdeps/ieee754/ldbl-128/e_j1l.c (__ieee754_y1l): Likewise.
+
 2017-02-10  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	* string/bits/string2.h (strchr): Remove define.
diff --git a/sysdeps/ieee754/ldbl-128/e_j0l.c b/sysdeps/ieee754/ldbl-128/e_j0l.c
index d7110071368..855b5a578ba 100644
--- a/sysdeps/ieee754/ldbl-128/e_j0l.c
+++ b/sysdeps/ieee754/ldbl-128/e_j0l.c
@@ -829,12 +829,7 @@ _Float128
   _Float128 xx, xinv, z, p, q, c, s, cc, ss;
 
   if (! isfinite (x))
-    {
-      if (x != x)
-	return x + x;
-      else
-	return 0;
-    }
+    return 1 / (x + x * x);
   if (x <= 0)
     {
       if (x < 0)
diff --git a/sysdeps/ieee754/ldbl-128/e_j1l.c b/sysdeps/ieee754/ldbl-128/e_j1l.c
index 9e782305d9d..db8dca0ab13 100644
--- a/sysdeps/ieee754/ldbl-128/e_j1l.c
+++ b/sysdeps/ieee754/ldbl-128/e_j1l.c
@@ -847,12 +847,7 @@ __ieee754_y1l (_Float128 x)
   _Float128 xx, xinv, z, p, q, c, s, cc, ss;
 
   if (! isfinite (x))
-    {
-      if (x != x)
-	return x + x;
-      else
-	return 0;
-    }
+    return 1 / (x + x * x);
   if (x <= 0)
     {
       if (x < 0)