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[libc++] Add
__truncating_cast
for safely casting float types to in…
…tegers This is needed anytime we need to clamp an arbitrary floating point value to an integer type. Thanks to Eric Fiselier for the patch. Differential Revision: https://reviews.llvm.org/D66836 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@370891 91177308-0d34-0410-b5e6-96231b3b80d8
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//===----------------------------------------------------------------------===// | ||
// | ||
// 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 | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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// __clamp_to_integral<IntT>(RealT) | ||
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// Test the conversion function that truncates floating point types to the | ||
// closest representable value for the specified integer type, or | ||
// numeric_limits<IntT>::max()/min() if the value isn't representable. | ||
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#include <limits> | ||
#include <cassert> | ||
#include <cmath> | ||
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template <class IntT> | ||
void test() { | ||
typedef std::numeric_limits<IntT> Lim; | ||
const bool MaxIsRepresentable = sizeof(IntT) < 8; | ||
const bool IsSigned = std::is_signed<IntT>::value; | ||
struct TestCase { | ||
double Input; | ||
IntT Expect; | ||
bool IsRepresentable; | ||
} TestCases[] = { | ||
{0, 0, true}, | ||
{1, 1, true}, | ||
{IsSigned ? static_cast<IntT>(-1) : 0, | ||
IsSigned ? static_cast<IntT>(-1) : 0, true}, | ||
{Lim::lowest(), Lim::lowest(), true}, | ||
{static_cast<double>(Lim::max()), Lim::max(), MaxIsRepresentable}, | ||
{static_cast<double>(Lim::max()) + 1, Lim::max(), false}, | ||
{static_cast<double>(Lim::max()) + 1024, Lim::max(), false}, | ||
{nextafter(static_cast<double>(Lim::max()), INFINITY), Lim::max(), false}, | ||
}; | ||
for (TestCase TC : TestCases) { | ||
auto res = std::__clamp_to_integral<IntT>(TC.Input); | ||
assert(res == TC.Expect); | ||
if (TC.IsRepresentable) { | ||
auto other = static_cast<IntT>(std::trunc(TC.Input)); | ||
assert(res == other); | ||
} else | ||
assert(res == Lim::min() || res == Lim::max()); | ||
} | ||
} | ||
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template <class IntT> | ||
void test_float() { | ||
typedef std::numeric_limits<IntT> Lim; | ||
const bool MaxIsRepresentable = sizeof(IntT) < 4; | ||
((void)MaxIsRepresentable); | ||
const bool IsSigned = std::is_signed<IntT>::value; | ||
struct TestCase { | ||
float Input; | ||
IntT Expect; | ||
bool IsRepresentable; | ||
} TestCases[] = { | ||
{0, 0, true}, | ||
{1, 1, true}, | ||
{IsSigned ? static_cast<IntT>(-1) : 0, | ||
IsSigned ? static_cast<IntT>(-1) : 0, true}, | ||
{Lim::lowest(), Lim::lowest(), true}, | ||
{static_cast<float>(Lim::max()), Lim::max(), MaxIsRepresentable }, | ||
{nextafter(static_cast<float>(Lim::max()), INFINITY), Lim::max(), false}, | ||
}; | ||
for (TestCase TC : TestCases) { | ||
auto res = std::__clamp_to_integral<IntT>(TC.Input); | ||
assert(res == TC.Expect); | ||
if (TC.IsRepresentable) { | ||
auto other = static_cast<IntT>(std::trunc(TC.Input)); | ||
assert(res == other); | ||
} else | ||
assert(res == Lim::min() || res == Lim::max()); | ||
} | ||
} | ||
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int main() { | ||
test<short>(); | ||
test<unsigned short>(); | ||
test<int>(); | ||
test<unsigned>(); | ||
test<long long>(); | ||
test<unsigned long long>(); | ||
test_float<short>(); | ||
test_float<int>(); | ||
test_float<long long>(); | ||
} |