Fix sin, sincos missing underflows (bug 16526, bug 16538).

Similar to various other bugs in this area, some sin and sincos
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.

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #16526]
	[BZ #16538]
	* sysdeps/ieee754/dbl-64/s_sin.c: Include <float.h>.
	(__sin): Force underflow exception for arguments with small
	absolute value.
	* sysdeps/ieee754/flt-32/k_sinf.c: Include <float.h>.
	(__kernel_sinf): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/ieee754/ldbl-128/k_sincosl.c: Include <float.h>.
	(__kernel_sincosl): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/ieee754/ldbl-128/k_sinl.c: Include <float.h>.
	(__kernel_sinl): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/ieee754/ldbl-128ibm/k_sincosl.c: Include <float.h>.
	(__kernel_sincosl): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/ieee754/ldbl-128ibm/k_sinl.c: Include <float.h>.
	(__kernel_sinl): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/ieee754/ldbl-96/k_sinl.c: Include <float.h>.
	(__kernel_sinl): Force underflow exception for arguments with
	small absolute value.
	* sysdeps/powerpc/fpu/k_sinf.c: Include <float.h>.
	(__kernel_sinf): Force underflow exception for arguments with
	small absolute value.
	* math/auto-libm-test-in: Add more tests of sin and sincos.
	* math/auto-libm-test-out: Regenerated.

1 files changed, 14 insertions, 6 deletions

diff --git a/sysdeps/ieee754/ldbl-128/k_sincosl.c b/sysdeps/ieee754/ldbl-128/k_sincosl.c
index 2f66dee6d8..7b5c4b0e81 100644
--- a/sysdeps/ieee754/ldbl-128/k_sincosl.c
+++ b/sysdeps/ieee754/ldbl-128/k_sincosl.c
@@ -17,6 +17,7 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -109,12 +110,19 @@ __kernel_sincosl(long double x, long double y, long double *sinx, long double *c
       /* Argument is small enough to approximate it by a Chebyshev
 	 polynomial of degree 16(17).  */
       if (tix < 0x3fc60000)		/* |x| < 2^-57 */
-	if (!((int)x))			/* generate inexact */
-	  {
-	    *sinx = x;
-	    *cosx = ONE;
-	    return;
-	  }
+	{
+	  if (fabsl (x) < LDBL_MIN)
+	    {
+	      long double force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
+	  if (!((int)x))			/* generate inexact */
+	    {
+	      *sinx = x;
+	      *cosx = ONE;
+	      return;
+	    }
+	}
       z = x * x;
       *sinx = x + (x * (z*(SIN1+z*(SIN2+z*(SIN3+z*(SIN4+
 			z*(SIN5+z*(SIN6+z*(SIN7+z*SIN8)))))))));