Fix tan missing underflows (bug 16517).

Similar to various other bugs in this area, some tan 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 #16517] * sysdeps/ieee754/dbl-64/s_tan.c: Include <float.h>. (tan): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/flt-32/k_tanf.c: Include <float.h>. (__kernel_tanf): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128ibm/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-96/k_tanl.c: Include <float.h>. (__kernel_tanl): Force underflow exception for arguments with small absolute value. * math/auto-libm-test-in: Add more tests of tan. * math/auto-libm-test-out: Regenerated.
git-mirror · Aug 7, 2015 · 37550cb · 37550cb
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diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,24 @@
+2015-08-07  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #16517]
+	* sysdeps/ieee754/dbl-64/s_tan.c: Include <float.h>.
+	(tan): Force underflow exception for arguments with small absolute
+	value.
+	* sysdeps/ieee754/flt-32/k_tanf.c: Include <float.h>.
+	(__kernel_tanf): Force underflow exception for arguments with
+	small absolute value.
+	* sysdeps/ieee754/ldbl-128/k_tanl.c: Include <float.h>.
+	(__kernel_tanl): Force underflow exception for arguments with
+	small absolute value.
+	* sysdeps/ieee754/ldbl-128ibm/k_tanl.c: Include <float.h>.
+	(__kernel_tanl): Force underflow exception for arguments with
+	small absolute value.
+	* sysdeps/ieee754/ldbl-96/k_tanl.c: Include <float.h>.
+	(__kernel_tanl): Force underflow exception for arguments with
+	small absolute value.
+	* math/auto-libm-test-in: Add more tests of tan.
+	* math/auto-libm-test-out: Regenerated.
+
 2015-08-07  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
 	Fix sysdeps/i386/fpu/s_scalbn.S build

diff --git a/NEWS b/NEWS
@@ -8,7 +8,7 @@ using `glibc' in the "product" field.
 Version 2.23
 
 * The following bugs are resolved with this release:
-  16519, 18265, 18525, 18618, 18647, 18661.
+  16517, 16519, 18265, 18525, 18618, 18647, 18661.
 
 Version 2.22
 

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
@@ -2659,6 +2659,10 @@ tan 9
 tan 10
 tan -0x1.062a48p+0
 tan -0x1.4f69cp+0
+tan min
+tan -min
+tan min_subnorm
+tan -min_subnorm
 
 tanh 0
 tanh -0

diff --git a/math/auto-libm-test-out b/math/auto-libm-test-out
diff --git a/sysdeps/ieee754/dbl-64/s_tan.c b/sysdeps/ieee754/dbl-64/s_tan.c
@@ -34,6 +34,7 @@
 /*********************************************************************/
 
 #include <errno.h>
+#include <float.h>
 #include "endian.h"
 #include <dla.h>
 #include "mpa.h"
@@ -91,6 +92,11 @@ tan (double x)
   /* (I) The case abs(x) <= 1.259e-8 */
   if (w <= g1.d)
     {
+      if (w < DBL_MIN)
+	{
+	  double force_underflow = x * x;
+	  math_force_eval (force_underflow);
+	}
       retval = x;
       goto ret;
     }

diff --git a/sysdeps/ieee754/flt-32/k_tanf.c b/sysdeps/ieee754/flt-32/k_tanf.c
@@ -17,6 +17,7 @@
 static char rcsid[] = "$NetBSD: k_tanf.c,v 1.4 1995/05/10 20:46:39 jtc Exp $";
 #endif
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 static const float
@@ -48,7 +49,17 @@ float __kernel_tanf(float x, float y, int iy)
 	if(ix<0x39000000)			/* x < 2**-13 */
 	    {if((int)x==0) {			/* generate inexact */
 		if((ix|(iy+1))==0) return one/fabsf(x);
-		else return (iy==1)? x: -one/x;
+		else if (iy == 1)
+		  {
+		    if (fabsf (x) < FLT_MIN)
+		      {
+			float force_underflow = x * x;
+			math_force_eval (force_underflow);
+		      }
+		    return x;
+		  }
+		else
+		  return -one / x;
 	    }
 	    }
 	if(ix>=0x3f2ca140) { 			/* |x|>=0.6744 */

diff --git a/sysdeps/ieee754/ldbl-128/k_tanl.c b/sysdeps/ieee754/ldbl-128/k_tanl.c
@@ -56,6 +56,7 @@
  *		       = 1 - 2*(tan(y) - (tan(y)^2)/(1+tan(y)))
  */
 
+#include <float.h>
 #include <libc-internal.h>
 #include <math.h>
 #include <math_private.h>
@@ -98,8 +99,17 @@ __kernel_tanl (long double x, long double y, int iy)
 	  if ((ix | u.parts32.w1 | u.parts32.w2 | u.parts32.w3
 	       | (iy + 1)) == 0)
 	    return one / fabs (x);
+	  else if (iy == 1)
+	    {
+	      if (fabsl (x) < LDBL_MIN)
+		{
+		  long double force_underflow = x * x;
+		  math_force_eval (force_underflow);
+		}
+	      return x;
+	    }
 	  else
-	    return (iy == 1) ? x : -one / x;
+	    return -one / x;
 	}
     }
   if (ix >= 0x3ffe5942) /* |x| >= 0.6743316650390625 */

diff --git a/sysdeps/ieee754/ldbl-128ibm/k_tanl.c b/sysdeps/ieee754/ldbl-128ibm/k_tanl.c
@@ -56,6 +56,7 @@
  *		       = 1 - 2*(tan(y) - (tan(y)^2)/(1+tan(y)))
  */
 
+#include <float.h>
 #include <libc-internal.h>
 #include <math.h>
 #include <math_private.h>
@@ -98,8 +99,17 @@ __kernel_tanl (long double x, long double y, int iy)
 	{
 	  if ((ix | lx | (iy + 1)) == 0)
 	    return one / fabs (x);
+	  else if (iy == 1)
+	    {
+	      if (fabsl (x) < LDBL_MIN)
+		{
+		  long double force_underflow = x * x;
+		  math_force_eval (force_underflow);
+		}
+	      return x;
+	    }
 	  else
-	    return (iy == 1) ? x : -one / x;
+	    return -one / x;
 	}
     }
   if (ix >= 0x3fe59420) /* |x| >= 0.6743316650390625 */

diff --git a/sysdeps/ieee754/ldbl-96/k_tanl.c b/sysdeps/ieee754/ldbl-96/k_tanl.c
@@ -56,6 +56,7 @@
  *		       = 1 - 2*(tan(y) - (tan(y)^2)/(1+tan(y)))
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 static const long double
@@ -94,8 +95,17 @@ __kernel_tanl (long double x, long double y, int iy)
 	{			/* generate inexact */
 	  if (x == 0 && iy == -1)
 	    return one / fabsl (x);
+	  else if (iy == 1)
+	    {
+	      if (absx < LDBL_MIN)
+		{
+		  long double force_underflow = x * x;
+		  math_force_eval (force_underflow);
+		}
+	      return x;
+	    }
 	  else
-	    return (iy == 1) ? x : -one / x;
+	    return -one / x;
 	}
     }
   if (absx >= 0.6743316650390625L)