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3b10c5d2ab
All representations of floating-point numbers in types with IEC 60559
binary exchange format are canonical. On the other hand, types with IEC
60559 extended formats, such as those implemented under ldbl-96 and
ldbl-128ibm, contain representations that are not canonical.
TS 18661-1 introduced the type-generic macro iscanonical, which returns
whether a floating-point value is canonical or not. In Glibc, this
type-generic macro is implemented using the macro __MATH_TG, which, when
support for float128 is enabled, relies on __builtin_types_compatible_p
to select between floating-point types. However, this use of
iscanonical breaks C++ applications, because the builtin is only
available in C mode.
This patch provides a C++ implementation of iscanonical that relies on
function overloading, rather than builtins, to select between
floating-point types.
Unlike the C++ implementations for iszero and issignaling, this
implementation ignores __NO_LONG_DOUBLE_MATH. The double type always
matches IEC 60559 double format, which is always canonical. Thus, when
double and long double are the same (__NO_LONG_DOUBLE_MATH), iscanonical
always returns 1 and is not implemented with __MATH_TG.
Tested for powerpc64, powerpc64le and x86_64.
[BZ #22235]
* math/math.h: Trivial fix for unbalanced parentheses in comment.
* math/Makefile [CXX] (tests): Add test-math-iscanonical.cc.
(CFLAGS-test-math-iscanonical.cc): New variable.
* math/test-math-iscanonical.cc: New file.
* sysdeps/ieee754/ldbl-96/bits/iscanonical.h (iscanonical):
Provide a C++ implementation based on function overloading,
rather than using __MATH_TG, which uses C-only builtins.
* sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h (iscanonical):
Likewise.
* sysdeps/powerpc/powerpc64le/Makefile
(CFLAGS-test-math-iscanonical.cc): New variable.
(cherry picked from commit aa0235dfde)
49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
/* Test for the C++ implementation of iscanonical.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#define _GNU_SOURCE 1
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#include <math.h>
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#include <stdio.h>
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static bool errors;
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template <class T>
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static void
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check_type ()
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{
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T val = 0;
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/* Check if iscanonical is available in C++ mode (bug 22235). */
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if (iscanonical (val) == 0)
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errors++;
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}
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static int
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do_test (void)
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{
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check_type<float> ();
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check_type<double> ();
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check_type<long double> ();
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#if __HAVE_DISTINCT_FLOAT128
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check_type<_Float128> ();
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#endif
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return errors;
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}
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#include <support/test-driver.c>
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