From: Joseph Myers <joseph@codesourcery.com>
Date: Fri, 25 May 2012 11:07:07 +0000 (+0000)
Subject: Fix acosf underflow (bug 14153).
X-Git-Tag: glibc-2.16-tps~163
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b65504975c97e1ec7aadaa75dcefb42e7e70fa1f;p=thirdparty%2Fglibc.git

Fix acosf underflow (bug 14153).
---

diff --git a/ChangeLog b/ChangeLog
index c6c2cad7257..ceb3f5af775 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2012-05-24  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #14153]
+	* sysdeps/ieee754/flt-32/e_acosf.c (__ieee754_acosf): Return pi/2
+	for |x| <= 2**-26, not 2**-57.
+	* math/libm-test.inc (acos_test): Do not allow spurious underflow
+	exception.
+
 2012-05-24  Jeff Law  <law@redhat.com>
 
 	* stdio-common/Makefile (tests): Add bug25.
diff --git a/NEWS b/NEWS
index 7ccfb903ef6..932934dbc83 100644
--- a/NEWS
+++ b/NEWS
@@ -28,7 +28,7 @@ Version 2.16
   13941, 13942, 13954, 13955, 13956, 13963, 13967, 13968, 13970, 13973,
   13979, 13983, 13986, 14012, 14027, 14033, 14034, 14036, 14040, 14043,
   14044, 14049, 14053, 14055, 14059, 14064, 14080, 14083, 14103, 14104,
-  14109, 14122, 14123
+  14109, 14122, 14123, 14153
 
 * ISO C11 support:
 
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 5946ca890b4..ed13f53ec87 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -804,8 +804,7 @@ acos_test (void)
   TEST_f_f (acos, 0.5, M_PI_6l*2.0);
   TEST_f_f (acos, -0.5, M_PI_6l*4.0);
   TEST_f_f (acos, 0.75L, 0.722734247813415611178377352641333362L);
-  /* Bug 14153: spurious exception may occur.  */
-  TEST_f_f (acos, 2e-17L, 1.57079632679489659923132169163975144L, UNDERFLOW_EXCEPTION_OK_FLOAT);
+  TEST_f_f (acos, 2e-17L, 1.57079632679489659923132169163975144L);
   TEST_f_f (acos, 0.0625L, 1.50825556499840522843072005474337068L);
   TEST_f_f (acos, 0x0.ffffffp0L, 3.4526698471620358760324948263873649728491e-4L);
   TEST_f_f (acos, -0x0.ffffffp0L, 3.1412473866050770348750401337968641476999L);
diff --git a/sysdeps/ieee754/flt-32/e_acosf.c b/sysdeps/ieee754/flt-32/e_acosf.c
index c0f1d4ea743..6f792f6604c 100644
--- a/sysdeps/ieee754/flt-32/e_acosf.c
+++ b/sysdeps/ieee754/flt-32/e_acosf.c
@@ -46,7 +46,7 @@ __ieee754_acosf(float x)
 	    return (x-x)/(x-x);		/* acos(|x|>1) is NaN */
 	}
 	if(ix<0x3f000000) {	/* |x| < 0.5 */
-	    if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
+	    if(ix<=0x32800000) return pio2_hi+pio2_lo;/*if|x|<=2**-26*/
 	    z = x*x;
 	    p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
 	    q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));