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: https://sourceware.org/git/?a=commitdiff_plain;h=b987917e6aa7ffe2fd74f0b6a989438e6edd0727;p=glibc.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 fac0e11c40..27f41f7ad0 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 d711007136..855b5a578b 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 9e782305d9..db8dca0ab1 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)