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GNU C Library master sources branch, master, updated. glibc-2.15-470-g48e4479
- From: jsm28 at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 22 Mar 2012 12:55:34 -0000
- Subject: GNU C Library master sources branch, master, updated. glibc-2.15-470-g48e4479
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http://sources.redhat.com/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=48e44791e4d4d755bf7a7dd083d87584dc4779e4
commit 48e44791e4d4d755bf7a7dd083d87584dc4779e4
Author: Joseph Myers <joseph@codesourcery.com>
Date: Thu Mar 22 12:55:19 2012 +0000
Fix exp2l inaccuracy (bug 13824).
diff --git a/ChangeLog b/ChangeLog
index a993315..599c340 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2012-03-22 Joseph Myers <joseph@codesourcery.com>
+ [BZ #13824]
+ * math/e_exp2l.c: Include <float.h>.
+ (__ieee754_exp2l): Handle overflow and underflow cases
+ separately. Only pass fractional part of argument to
+ __ieee754_expl.
+ * math/libm-test.inc (exp2_test): Add more tests.
+
* sysdeps/ieee754/ldbl-128/k_cosl.c (__kernel_cosl): Negate y if
negating x to take absolute value.
* sysdeps/ieee754/ldbl-128/k_sincosl.c (__kernel_sincosl):
diff --git a/NEWS b/NEWS
index 78fac7b..5f9648e 100644
--- a/NEWS
+++ b/NEWS
@@ -11,12 +11,12 @@ Version 2.16
174, 350, 411, 2541, 2547, 2548, 2551, 2552, 2553, 2554, 2562, 2563, 2565,
2566, 2576, 3335, 3976, 3992, 4026, 4108, 4596, 4822, 5077, 5461, 5805,
- 5993, 6471, 6730, 6884, 6907, 6911, 9739, 9902, 10110, 10135, 10140, 10210,
- 10545, 10716, 11174, 11322, 11365, 11451, 11494, 12047, 13058, 13525,
- 13526, 13527, 13528, 13529, 13530, 13531, 13532, 13533, 13547, 13551,
- 13552, 13553, 13555, 13559, 13566, 13583, 13618, 13637, 13656, 13658,
- 13673, 13695, 13704, 13706, 13726, 13738, 13786, 13792, 13806, 13840,
- 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13883
+ 5993, 6471, 6730, 6884, 6907, 6911, 9739, 9902, 10110, 10135, 10140,
+ 10210, 10545, 10716, 11174, 11322, 11365, 11451, 11494, 12047, 13058,
+ 13525, 13526, 13527, 13528, 13529, 13530, 13531, 13532, 13533, 13547,
+ 13551, 13552, 13553, 13555, 13559, 13566, 13583, 13618, 13637, 13656,
+ 13658, 13673, 13695, 13704, 13706, 13726, 13738, 13786, 13792, 13806,
+ 13824, 13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13883
* ISO C11 support:
diff --git a/math/e_exp2l.c b/math/e_exp2l.c
index e7e4939..8904d3e 100644
--- a/math/e_exp2l.c
+++ b/math/e_exp2l.c
@@ -1,11 +1,49 @@
+/* Compute 2^x.
+ Copyright (C) 2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
#include <math.h>
#include <math_private.h>
+#include <float.h>
long double
__ieee754_exp2l (long double x)
{
- /* This is a very stupid and inprecise implementation. It'll get
- replaced sometime (soon?). */
- return __ieee754_expl (M_LN2l * x);
+ if (__builtin_expect (isless (x, (long double) LDBL_MAX_EXP), 1))
+ {
+ if (__builtin_expect (isgreaterequal (x, (long double) (LDBL_MIN_EXP
+ - LDBL_MANT_DIG
+ - 1)), 1))
+ {
+ int intx = (int) x;
+ long double fractx = x - intx;
+ return __scalbnl (__ieee754_expl (M_LN2l * fractx), intx);
+ }
+ else
+ {
+ /* Underflow or exact zero. */
+ if (__isinfl (x))
+ return 0;
+ else
+ return LDBL_MIN * LDBL_MIN;
+ }
+ }
+ else
+ /* Infinity, NaN or overflow. */
+ return LDBL_MAX * x;
}
strong_alias (__ieee754_exp2l, __exp2l_finite)
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 05a000e..fad767d 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -3127,6 +3127,21 @@ exp2_test (void)
TEST_f_f (exp2, -1e6, 0);
TEST_f_f (exp2, 0.75L, 1.68179283050742908606225095246642979L);
+ TEST_f_f (exp2, 100.5, 1.792728671193156477399422023278661496394e+30L);
+ TEST_f_f (exp2, 127, 0x1p127);
+ TEST_f_f (exp2, -149, 0x1p-149);
+
+#ifndef TEST_FLOAT
+ TEST_f_f (exp2, 1000.25, 1.274245659452564874772384918171765416737e+301L);
+ TEST_f_f (exp2, 1023, 0x1p1023);
+ TEST_f_f (exp2, -1074, 0x1p-1074);
+#endif
+
+#if defined TEST_LDOUBLE && LDBL_MAX_EXP >= 16384
+ TEST_f_f (exp2, 16383, 0x1p16383L);
+ TEST_f_f (exp2, -16400, 0x1p-16400L);
+#endif
+
END (exp2);
}
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 7 +++++++
NEWS | 12 ++++++------
math/e_exp2l.c | 44 +++++++++++++++++++++++++++++++++++++++++---
math/libm-test.inc | 15 +++++++++++++++
4 files changed, 69 insertions(+), 9 deletions(-)
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