Fix atanhl missing underflows (bug 16352).

Similar to various other bugs in this area, some atanh implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact.  This patch forces the exception in a
similar way to previous fixes.  (No change in this regard is needed
for the i386 implementation; special handling to force underflows in
these cases will only be needed there when the spurious underflows,
bug 18049, get fixed.)

Tested for x86_64, x86, powerpc and mips64.

	[BZ #16352]
	* sysdeps/i386/fpu/e_atanh.S (dbl_min): New object.
	(__ieee754_atanh): Force underflow exception for results with
	small absolute value.
	* sysdeps/i386/fpu/e_atanhf.S (flt_min): New object.
	(__ieee754_atanhf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/dbl-64/e_atanh.c: Include <float.h>.
	(__ieee754_atanh): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/flt-32/e_atanhf.c: Include <float.h>.
	(__ieee754_atanhf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128ibm/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-96/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* math/auto-libm-test-in: Do not allow missing underflow
	exceptions from atanh.
	* math/auto-libm-test-out: Regenerated.

5 files changed, 38 insertions, 2 deletions

diff --git a/sysdeps/ieee754/dbl-64/e_atanh.c b/sysdeps/ieee754/dbl-64/e_atanh.c
index b95399ddab..6b00b800f2 100644
--- a/sysdeps/ieee754/dbl-64/e_atanh.c
+++ b/sysdeps/ieee754/dbl-64/e_atanh.c
@@ -35,6 +35,7 @@
 
  */
 
+#include <float.h>
 #include <inttypes.h>
 #include <math.h>
 #include <math_private.h>
@@ -51,6 +52,11 @@ __ieee754_atanh (double x)
       if (__glibc_unlikely (xa < 0x1.0p-28))
 	{
 	  math_force_eval (huge + x);
+	  if (fabs (x) < DBL_MIN)
+	    {
+	      double force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
 	  return x;
 	}
 
diff --git a/sysdeps/ieee754/flt-32/e_atanhf.c b/sysdeps/ieee754/flt-32/e_atanhf.c
index a6d8bd139f..bc74960e16 100644
--- a/sysdeps/ieee754/flt-32/e_atanhf.c
+++ b/sysdeps/ieee754/flt-32/e_atanhf.c
@@ -35,6 +35,7 @@
 
  */
 
+#include <float.h>
 #include <inttypes.h>
 #include <math.h>
 #include <math_private.h>
@@ -51,6 +52,11 @@ __ieee754_atanhf (float x)
       if (__glibc_unlikely (xa < 0x1.0p-28f))
 	{
 	  math_force_eval (huge + x);
+	  if (fabsf (x) < FLT_MIN)
+	    {
+	      float force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
 	  return x;
 	}
 
diff --git a/sysdeps/ieee754/ldbl-128/e_atanhl.c b/sysdeps/ieee754/ldbl-128/e_atanhl.c
index c5cceb5224..a5a7ee0712 100644
--- a/sysdeps/ieee754/ldbl-128/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-128/e_atanhl.c
@@ -32,6 +32,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -57,7 +58,15 @@ __ieee754_atanhl(long double x)
 	    else
 	      return (x-x)/(x-x);
 	  }
-	if(ix<0x3fc60000 && (huge+x)>zero) return x;	/* x < 2^-57 */
+	if(ix<0x3fc60000 && (huge+x)>zero)	/* x < 2^-57 */
+	  {
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
+	    return x;
+	  }
 
 	if(ix<0x3ffe0000) {		/* x < 0.5 */
 	    t = u.value+u.value;
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c b/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
index 5a989992f5..bcd1fce4ed 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
@@ -28,6 +28,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -54,7 +55,15 @@ __ieee754_atanhl(long double x)
 	    if (t == one)
 		return x/zero;
 	}
-	if(ix<0x3c70000000000000LL&&(huge+x)>zero) return x;	/* x<2**-56 */
+	if(ix<0x3c70000000000000LL&&(huge+x)>zero)	/* x<2**-56 */
+	  {
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
+	    return x;
+	  }
 	x = fabsl (x);
 	if(ix<0x3fe0000000000000LL) {		/* x < 0.5 */
 	    t = x+x;
diff --git a/sysdeps/ieee754/ldbl-96/e_atanhl.c b/sysdeps/ieee754/ldbl-96/e_atanhl.c
index 305d50e309..9a957c9065 100644
--- a/sysdeps/ieee754/ldbl-96/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-96/e_atanhl.c
@@ -32,6 +32,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -54,6 +55,11 @@ __ieee754_atanhl(long double x)
 	    return x/zero;
 	if(ix<0x3fdf) {
 	    math_force_eval(huge+x);
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
 	    return x;	/* x<2**-32 */
 	}
 	SET_LDOUBLE_EXP(x,ix);