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DO NOT MERGE: [libc++] Move __clamp_to_integral to <cmath>, and harden against min()/max() macros

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@370900 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 87e6185621d332d2ef8695b94778663380c83bb9)

Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=994957
Bug: http://b/139690488
Change-Id: Ice92a8ea6f675be069a70c5ad1003cf99b4fc474
(cherry picked from commit 82e0483c4a47233ed2f7bab545b32e5ddd474e59)
(cherry picked from commit 21beede0ddfffab3e31961a68f7282b54f3ab52a)
This commit is contained in:
Louis Dionne
2019-09-04 13:35:03 +00:00
committed by Dan Albert
parent 55b6136b3a
commit 7af7a63c2e
3 changed files with 51 additions and 34 deletions
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32
include/cmath
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@@ -303,6 +303,8 @@ long double truncl(long double x);
#include <__config> #include <__config>
#include <math.h> #include <math.h>
#include <limits>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header #pragma GCC system_header
@@ -612,6 +614,36 @@ __libcpp_isfinite(_A1 __lcpp_x) _NOEXCEPT
return isfinite(__lcpp_x); return isfinite(__lcpp_x);
} }
template <class _IntT, class _FloatT,
bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
static_assert(is_integral<_IntT>::value, "must be an integral type");
static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
static_assert(is_same<_FloatT, float>::value || is_same<_FloatT, double>::value
|| is_same<_FloatT,long double>::value, "unsupported floating point type");
return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits);
}
// Convert a floating point number to the specified integral type after
// clamping to the integral types representable range.
//
// The behavior is undefined if `__r` is NaN.
template <class _IntT, class _RealT>
_LIBCPP_INLINE_VISIBILITY
_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
using _Lim = std::numeric_limits<_IntT>;
const _IntT _MaxVal = std::__max_representable_int_for_float<_IntT, _RealT>();
if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) {
return _Lim::max();
} else if (__r <= _Lim::lowest()) {
return _Lim::min();
}
return static_cast<_IntT>(__r);
}
_LIBCPP_END_NAMESPACE_STD _LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_CMATH #endif // _LIBCPP_CMATH

34
include/math.h
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@@ -1426,40 +1426,6 @@ trunc(_A1 __lcpp_x) _NOEXCEPT {return ::trunc((double)__lcpp_x);}
#endif // !(defined(_LIBCPP_MSVCRT) && ((_VC_CRT_MAJOR_VERSION-0) < 14)) #endif // !(defined(_LIBCPP_MSVCRT) && ((_VC_CRT_MAJOR_VERSION-0) < 14))
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _IntT, class _FloatT,
bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
static_assert(is_integral<_IntT>::value, "must be an integral type");
static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
static_assert(_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value
|| _IsSame<_FloatT,long double>::value, "unsupported floating point type");
return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits);
}
// Convert a floating point number to the specified integral type after
// clamping to the integral types representable range.
//
// The behavior is undefined if `__r` is NaN.
template <class _IntT, class _RealT>
_LIBCPP_INLINE_VISIBILITY
_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
using _Lim = std::numeric_limits<_IntT>;
const _IntT _MaxVal = std::__max_representable_int_for_float<_IntT, _RealT>();
if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) {
return _Lim::max();
} else if (__r <= _Lim::lowest()) {
return _Lim::min();
}
return static_cast<_IntT>(__r);
}
_LIBCPP_END_NAMESPACE_STD
} // extern "C++" } // extern "C++"
#endif // __cplusplus #endif // __cplusplus

19
test/libcxx/numerics/c.math/undef_min_max.pass.cpp Normal file
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@@ -0,0 +1,19 @@
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic ignored "-W#warnings"
#endif
#define min THIS IS A NASTY MACRO!
#define max THIS IS A NASTY MACRO!
#include <cmath>
#include "test_macros.h"
int main(int, char**) { return 0; }