Fix j1, jn missing underflows (bug 16559).

Similar to various other bugs in this area, j1 and jn implementations
can fail to raise the underflow exception when the internal
computation is exact although the actual function is inexact.  This
patch forces the exception in a similar way to other such fixes.  (The
ldbl-128 / ldbl-128ibm j1l implementation is different and doesn't
need a change for this until spurious underflows in it are fixed.)

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #16559]
	* sysdeps/ieee754/dbl-64/e_j1.c: Include <float.h>.
	(__ieee754_j1): Force underflow exception for small results.
	* sysdeps/ieee754/dbl-64/e_jn.c (__ieee754_jn): Likewise.
	* sysdeps/ieee754/flt-32/e_j1f.c: Include <float.h>.
	(__ieee754_j1f): Force underflow exception for small results.
	* sysdeps/ieee754/flt-32/e_jnf.c (__ieee754_jnf): Likewise.
	* sysdeps/ieee754/ldbl-128/e_jnl.c (__ieee754_jnl): Likewise.
	* sysdeps/ieee754/ldbl-128ibm/e_jnl.c (__ieee754_jnl): Likewise.
	* sysdeps/ieee754/ldbl-96/e_j1l.c: Include <float.h>.
	(__ieee754_j1l): Force underflow exception for small results.
	* sysdeps/ieee754/ldbl-96/e_jnl.c (__ieee754_jnl): Likewise.
	* math/auto-libm-test-in: Add more tests of j1 and jn.
	* math/auto-libm-test-out: Regenerated.

8 files changed, 55 insertions, 5 deletions

diff --git a/sysdeps/ieee754/dbl-64/e_j1.c b/sysdeps/ieee754/dbl-64/e_j1.c
index 653f33abe1..26ffdfe282 100644
--- a/sysdeps/ieee754/dbl-64/e_j1.c
+++ b/sysdeps/ieee754/dbl-64/e_j1.c
@@ -59,6 +59,7 @@
  */
 
 #include <errno.h>
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -124,8 +125,16 @@ __ieee754_j1 (double x)
     }
   if (__glibc_unlikely (ix < 0x3e400000))                  /* |x|<2**-27 */
     {
-      if (huge + x > one)
-	return 0.5 * x;                 /* inexact if x!=0 necessary */
+      if (huge + x > one)                 /* inexact if x!=0 necessary */
+	{
+	  double ret = 0.5 * x;
+	  if (fabs (ret) < DBL_MIN)
+	    {
+	      double force_underflow = ret * ret;
+	      math_force_eval (force_underflow);
+	    }
+	  return ret;
+	}
     }
   z = x * x;
   r1 = z * R[0]; z2 = z * z;
diff --git a/sysdeps/ieee754/dbl-64/e_jn.c b/sysdeps/ieee754/dbl-64/e_jn.c
index b0ddd5e841..ccef2dcd80 100644
--- a/sysdeps/ieee754/dbl-64/e_jn.c
+++ b/sysdeps/ieee754/dbl-64/e_jn.c
@@ -246,6 +246,11 @@ __ieee754_jn (int n, double x)
   }
   if (ret == 0)
     ret = __copysign (DBL_MIN, ret) * DBL_MIN;
+  else if (fabs (ret) < DBL_MIN)
+    {
+      double force_underflow = ret * ret;
+      math_force_eval (force_underflow);
+    }
   return ret;
 }
 strong_alias (__ieee754_jn, __jn_finite)
diff --git a/sysdeps/ieee754/flt-32/e_j1f.c b/sysdeps/ieee754/flt-32/e_j1f.c
index 7ffb57e806..63de21f609 100644
--- a/sysdeps/ieee754/flt-32/e_j1f.c
+++ b/sysdeps/ieee754/flt-32/e_j1f.c
@@ -14,6 +14,7 @@
  */
 
 #include <errno.h>
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -69,7 +70,14 @@ __ieee754_j1f(float x)
 		else	 return  z;
 	}
 	if(__builtin_expect(ix<0x32000000, 0)) {	/* |x|<2**-27 */
-	    if(huge+x>one) return (float)0.5*x;/* inexact if x!=0 necessary */
+	    if(huge+x>one) {		/* inexact if x!=0 necessary */
+		float ret = (float) 0.5 * x;
+		if (fabsf (ret) < FLT_MIN) {
+		    float force_underflow = ret * ret;
+		    math_force_eval (force_underflow);
+		}
+		return ret;
+	    }
 	}
 	z = x*x;
 	r =  z*(r00+z*(r01+z*(r02+z*r03)));
diff --git a/sysdeps/ieee754/flt-32/e_jnf.c b/sysdeps/ieee754/flt-32/e_jnf.c
index ec5a81b653..44a3761adb 100644
--- a/sysdeps/ieee754/flt-32/e_jnf.c
+++ b/sysdeps/ieee754/flt-32/e_jnf.c
@@ -170,6 +170,10 @@ __ieee754_jnf(int n, float x)
     }
     if (ret == 0)
 	ret = __copysignf (FLT_MIN, ret) * FLT_MIN;
+    else if (fabsf (ret) < FLT_MIN) {
+	float force_underflow = ret * ret;
+	math_force_eval (force_underflow);
+    }
     return ret;
 }
 strong_alias (__ieee754_jnf, __jnf_finite)
diff --git a/sysdeps/ieee754/ldbl-128/e_jnl.c b/sysdeps/ieee754/ldbl-128/e_jnl.c
index 14d65ff081..a419994a86 100644
--- a/sysdeps/ieee754/ldbl-128/e_jnl.c
+++ b/sysdeps/ieee754/ldbl-128/e_jnl.c
@@ -297,6 +297,11 @@ __ieee754_jnl (int n, long double x)
   }
   if (ret == 0)
     ret = __copysignl (LDBL_MIN, ret) * LDBL_MIN;
+  else if (fabsl (ret) < LDBL_MIN)
+    {
+      long double force_underflow = ret * ret;
+      math_force_eval (force_underflow);
+    }
   return ret;
 }
 strong_alias (__ieee754_jnl, __jnl_finite)
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
index 5d0a2b5b6a..7594196a1f 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_jnl.c
@@ -297,6 +297,11 @@ __ieee754_jnl (int n, long double x)
   }
   if (ret == 0)
     ret = __copysignl (LDBL_MIN, ret) * LDBL_MIN;
+  else if (fabsl (ret) < LDBL_MIN)
+    {
+      long double force_underflow = ret * ret;
+      math_force_eval (force_underflow);
+    }
   return ret;
 }
 strong_alias (__ieee754_jnl, __jnl_finite)
diff --git a/sysdeps/ieee754/ldbl-96/e_j1l.c b/sysdeps/ieee754/ldbl-96/e_j1l.c
index 1bd54995a8..46e28dfe11 100644
--- a/sysdeps/ieee754/ldbl-96/e_j1l.c
+++ b/sysdeps/ieee754/ldbl-96/e_j1l.c
@@ -72,6 +72,7 @@
  */
 
 #include <errno.h>
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -150,8 +151,16 @@ __ieee754_j1l (long double x)
     }
   if (__glibc_unlikely (ix < 0x3fde))       /* |x| < 2^-33 */
     {
-      if (huge + x > one)
-	return 0.5 * x;		/* inexact if x!=0 necessary */
+      if (huge + x > one)		/* inexact if x!=0 necessary */
+	{
+	  long double ret = 0.5 * x;
+	  if (fabsl (ret) < LDBL_MIN)
+	    {
+	      long double force_underflow = ret * ret;
+	      math_force_eval (force_underflow);
+	    }
+	  return ret;
+	}
     }
   z = x * x;
   r = z * (R[0] + z * (R[1]+ z * (R[2] + z * (R[3] + z * R[4]))));
diff --git a/sysdeps/ieee754/ldbl-96/e_jnl.c b/sysdeps/ieee754/ldbl-96/e_jnl.c
index 49c9c421b0..2f3a452f55 100644
--- a/sysdeps/ieee754/ldbl-96/e_jnl.c
+++ b/sysdeps/ieee754/ldbl-96/e_jnl.c
@@ -290,6 +290,11 @@ __ieee754_jnl (int n, long double x)
   }
   if (ret == 0)
     ret = __copysignl (LDBL_MIN, ret) * LDBL_MIN;
+  else if (fabsl (ret) < LDBL_MIN)
+    {
+      long double force_underflow = ret * ret;
+      math_force_eval (force_underflow);
+    }
   return ret;
 }
 strong_alias (__ieee754_jnl, __jnl_finite)