From ec0ce0d3be4ae21add09139c705852ed8bb114c7 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Thu, 26 Feb 2015 17:18:54 +0000
Subject: Fix asin missing underflows (bug 16351).

Similar to various other bugs in this area, some asin 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, powerpc and mips64.

	[BZ #16351]
	* sysdeps/i386/fpu/e_asin.S (dbl_min): New object.
	(MO): New macro.
	(__ieee754_asin): Force underflow exception for results with small
	absolute value.
	* sysdeps/i386/fpu/e_asinf.S (flt_min): New object.
	(MO): New macro.
	(__ieee754_asinf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/dbl-64/e_asin.c: Include <float.h> and <math.h>.
	(__ieee754_asin): Force underflow exception for results with small
	absolute value.
	* sysdeps/ieee754/flt-32/e_asinf.c: Include <float.h>.
	(__ieee754_asinf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128/e_asinl.c: Include <float.h>.
	(__ieee754_asinl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128ibm/e_asinl.c: Include <float.h>.
	(__ieee754_asinl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-96/e_asinl.c: Include <float.h>.
	(__ieee754_asinl): Force underflow exception for results with
	small absolute value.
	* sysdeps/x86_64/fpu/multiarch/e_asin.c [HAVE_FMA4_SUPPORT]:
	Include <math.h>.
	* math/auto-libm-test-in: Do not mark underflow exceptions as
	possibly missing for bug 16351.
	* math/auto-libm-test-out: Regenerated.
---
 sysdeps/ieee754/dbl-64/e_asin.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'sysdeps/ieee754/dbl-64')

diff --git a/sysdeps/ieee754/dbl-64/e_asin.c b/sysdeps/ieee754/dbl-64/e_asin.c
index e90f47ccc2..b87e557988 100644
--- a/sysdeps/ieee754/dbl-64/e_asin.c
+++ b/sysdeps/ieee754/dbl-64/e_asin.c
@@ -39,6 +39,8 @@
 #include "powtwo.tbl"
 #include "MathLib.h"
 #include "uasncs.h"
+#include <float.h>
+#include <math.h>
 #include <math_private.h>
 
 #ifndef SECTION
@@ -67,7 +69,15 @@ __ieee754_asin(double x){
   m = u.i[HIGH_HALF];
   k = 0x7fffffff&m;              /* no sign */
 
-  if (k < 0x3e500000) return x;  /* for x->0 => sin(x)=x */
+  if (k < 0x3e500000)
+    {
+      if (fabs (x) < DBL_MIN)
+	{
+	  double force_underflow = x * x;
+	  math_force_eval (force_underflow);
+	}
+      return x;  /* for x->0 => sin(x)=x */
+    }
   /*----------------------2^-26 <= |x| < 2^ -3    -----------------*/
   else
   if (k < 0x3fc00000) {
-- 
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