From: Gabriel F. T. Gomes <gftg@linux.vnet.ibm.com>
Date: Mon, 13 Feb 2017 00:36:27 +0000 (-0200)
Subject: Fix y0 and y1 exception handling for zero input [BZ #21134]
X-Git-Tag: glibc-2.26~785
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4918e5f4cd63290bb0b2c614f52092ca6a779126;p=thirdparty%2Fglibc.git

Fix y0 and y1 exception handling for zero input [BZ #21134]

The Bessel functions of the second type (Yn) should raise the "divide
by zero" exception when input is zero (both positive and negative).
Current code gives the right output, but fails to set the exception.
This error is exposed for float, double, and 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, set the exception as expected.

Tested for powerpc64le.

	[BZ #21134]
	* sysdeps/ieee754/dbl-64/e_j0.c (__ieee754_y0): Raise the
	"divide by zero" exception when the input is zero.
	* sysdeps/ieee754/dbl-64/e_j1.c (__ieee754_y1): Likewise.
	* sysdeps/ieee754/flt-32/e_j0f.c (__ieee754_y0f): Likewise.
	* sysdeps/ieee754/flt-32/e_j1f.c (__ieee754_y1f): Likewise.
	* sysdeps/ieee754/ldbl-128/e_j0l.c (__ieee754_y0l): Likewise.
	* sysdeps/ieee754/ldbl-128/e_j1l.c (__ieee754_y1l): Likewise.
---

diff --git a/ChangeLog b/ChangeLog
index b040928a333..62961a2940a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2017-02-15  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>
+
+	[BZ #21134]
+	* sysdeps/ieee754/dbl-64/e_j0.c (__ieee754_y0): Raise the
+	"divide by zero" exception when the input is zero.
+	* sysdeps/ieee754/dbl-64/e_j1.c (__ieee754_y1): Likewise.
+	* sysdeps/ieee754/flt-32/e_j0f.c (__ieee754_y0f): Likewise.
+	* sysdeps/ieee754/flt-32/e_j1f.c (__ieee754_y1f): Likewise.
+	* sysdeps/ieee754/ldbl-128/e_j0l.c (__ieee754_y0l): Likewise.
+	* sysdeps/ieee754/ldbl-128/e_j1l.c (__ieee754_y1l): Likewise.
+
 2017-02-15  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/x86_64/fpu/test-double-vlen2.c: Move most contents to,
diff --git a/sysdeps/ieee754/dbl-64/e_j0.c b/sysdeps/ieee754/dbl-64/e_j0.c
index 9f25aa855e8..4b440cf0d04 100644
--- a/sysdeps/ieee754/dbl-64/e_j0.c
+++ b/sysdeps/ieee754/dbl-64/e_j0.c
@@ -169,7 +169,7 @@ __ieee754_y0 (double x)
   if (ix >= 0x7ff00000)
     return one / (x + x * x);
   if ((ix | lx) == 0)
-    return -HUGE_VAL + x;                  /* -inf and overflow exception.  */
+    return -1 / zero; /* -inf and divide by zero exception.  */
   if (hx < 0)
     return zero / (zero * x);
   if (ix >= 0x40000000)         /* |x| >= 2.0 */
diff --git a/sysdeps/ieee754/dbl-64/e_j1.c b/sysdeps/ieee754/dbl-64/e_j1.c
index 4827fbf3d39..eb446fd102d 100644
--- a/sysdeps/ieee754/dbl-64/e_j1.c
+++ b/sysdeps/ieee754/dbl-64/e_j1.c
@@ -174,7 +174,7 @@ __ieee754_y1 (double x)
   if (__glibc_unlikely (ix >= 0x7ff00000))
     return one / (x + x * x);
   if (__glibc_unlikely ((ix | lx) == 0))
-    return -HUGE_VAL + x;
+    return -1 / zero; /* -inf and divide by zero exception.  */
   /* -inf and overflow exception.  */;
   if (__glibc_unlikely (hx < 0))
     return zero / (zero * x);
diff --git a/sysdeps/ieee754/flt-32/e_j0f.c b/sysdeps/ieee754/flt-32/e_j0f.c
index bd0b80fdb0b..b783dd069dd 100644
--- a/sysdeps/ieee754/flt-32/e_j0f.c
+++ b/sysdeps/ieee754/flt-32/e_j0f.c
@@ -105,7 +105,7 @@ __ieee754_y0f(float x)
 	ix = 0x7fffffff&hx;
     /* Y0(NaN) is NaN, y0(-inf) is Nan, y0(inf) is 0, y0(0) is -inf.  */
 	if(ix>=0x7f800000) return  one/(x+x*x);
-	if(ix==0) return -HUGE_VALF+x;  /* -inf and overflow exception.  */
+	if(ix==0) return -1/zero; /* -inf and divide by zero exception.  */
 	if(hx<0) return zero/(zero*x);
 	if(ix >= 0x40000000) {  /* |x| >= 2.0 */
 	/* y0(x) = sqrt(2/(pi*x))*(p0(x)*sin(x0)+q0(x)*cos(x0))
diff --git a/sysdeps/ieee754/flt-32/e_j1f.c b/sysdeps/ieee754/flt-32/e_j1f.c
index f359a3d9ba6..805a87d85b7 100644
--- a/sysdeps/ieee754/flt-32/e_j1f.c
+++ b/sysdeps/ieee754/flt-32/e_j1f.c
@@ -112,7 +112,7 @@ __ieee754_y1f(float x)
     /* if Y1(NaN) is NaN, Y1(-inf) is NaN, Y1(inf) is 0 */
 	if(__builtin_expect(ix>=0x7f800000, 0)) return  one/(x+x*x);
 	if(__builtin_expect(ix==0, 0))
-		return -HUGE_VALF+x;  /* -inf and overflow exception.  */
+		return -1/zero; /* -inf and divide by zero exception.  */
 	if(__builtin_expect(hx<0, 0)) return zero/(zero*x);
 	if(ix >= 0x40000000) {  /* |x| >= 2.0 */
 		SET_RESTORE_ROUNDF (FE_TONEAREST);
diff --git a/sysdeps/ieee754/ldbl-128/e_j0l.c b/sysdeps/ieee754/ldbl-128/e_j0l.c
index 855b5a578ba..fb8d3518cea 100644
--- a/sysdeps/ieee754/ldbl-128/e_j0l.c
+++ b/sysdeps/ieee754/ldbl-128/e_j0l.c
@@ -834,7 +834,7 @@ _Float128
     {
       if (x < 0)
 	return (zero / (zero * x));
-      return -HUGE_VALL + x;
+      return -1 / zero; /* -inf and divide by zero exception.  */
     }
   xx = fabsl (x);
   if (xx <= 0x1p-57)
diff --git a/sysdeps/ieee754/ldbl-128/e_j1l.c b/sysdeps/ieee754/ldbl-128/e_j1l.c
index db8dca0ab13..6fc69faa3c5 100644
--- a/sysdeps/ieee754/ldbl-128/e_j1l.c
+++ b/sysdeps/ieee754/ldbl-128/e_j1l.c
@@ -852,7 +852,7 @@ __ieee754_y1l (_Float128 x)
     {
       if (x < 0)
 	return (zero / (zero * x));
-      return -HUGE_VALL + x;
+      return -1 / zero; /* -inf and divide by zero exception.  */
     }
   xx = fabsl (x);
   if (xx <= 0x1p-114)