Fix std::midpoint for denormal values
* include/std/numeric (midpoint(T, T)): Change implementation for floating-point types to avoid incorrect rounding of denormals. * testsuite/26_numerics/midpoint/floating.cc: Add check for correct rounding with denormals. * testsuite/26_numerics/gcd/gcd_neg.cc: Adjust dg-error line numbers. * testsuite/26_numerics/lcm/lcm_neg.cc: Likewise. From-SVN: r272616
This commit is contained in:
parent
ff164b601b
commit
a3c8d7fbe2
|
@ -1,5 +1,12 @@
|
|||
2019-06-24 Jonathan Wakely <jwakely@redhat.com>
|
||||
|
||||
* include/std/numeric (midpoint(T, T)): Change implementation for
|
||||
floating-point types to avoid incorrect rounding of denormals.
|
||||
* testsuite/26_numerics/midpoint/floating.cc: Add check for correct
|
||||
rounding with denormals.
|
||||
* testsuite/26_numerics/gcd/gcd_neg.cc: Adjust dg-error line numbers.
|
||||
* testsuite/26_numerics/lcm/lcm_neg.cc: Likewise.
|
||||
|
||||
* testsuite/18_support/headers/cfloat/values_c++17.cc: New test.
|
||||
|
||||
2019-06-20 Jonathan Wakely <jwakely@redhat.com>
|
||||
|
|
|
@ -69,9 +69,8 @@
|
|||
* @defgroup numerics Numerics
|
||||
*
|
||||
* Components for performing numeric operations. Includes support for
|
||||
* for complex number types, random number generation, numeric
|
||||
* (n-at-a-time) arrays, generalized numeric algorithms, and special
|
||||
* math functions.
|
||||
* complex number types, random number generation, numeric (n-at-a-time)
|
||||
* arrays, generalized numeric algorithms, and mathematical special functions.
|
||||
*/
|
||||
|
||||
#if __cplusplus >= 201402L
|
||||
|
@ -156,11 +155,22 @@ namespace __detail
|
|||
|
||||
#endif // C++17
|
||||
|
||||
_GLIBCXX_END_NAMESPACE_VERSION
|
||||
} // namespace std
|
||||
|
||||
#endif // C++14
|
||||
|
||||
#if __cplusplus > 201703L
|
||||
#include <limits>
|
||||
#include <bits/std_abs.h>
|
||||
|
||||
namespace std _GLIBCXX_VISIBILITY(default)
|
||||
{
|
||||
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
||||
// midpoint
|
||||
# define __cpp_lib_interpolate 201902L
|
||||
|
||||
template<typename _Tp>
|
||||
template<typename _Tp>
|
||||
constexpr
|
||||
enable_if_t<__and_v<is_arithmetic<_Tp>, is_same<remove_cv_t<_Tp>, _Tp>,
|
||||
__not_<is_same<_Tp, bool>>>,
|
||||
|
@ -182,11 +192,17 @@ template<typename _Tp>
|
|||
}
|
||||
return __a + __k * _Tp(_Up(__M - __m) / 2);
|
||||
}
|
||||
else
|
||||
else // is_floating
|
||||
{
|
||||
return __builtin_isnormal(__a) && __builtin_isnormal(__b)
|
||||
? __a / 2 + __b / 2
|
||||
: (__a + __b) / 2;
|
||||
constexpr _Tp __lo = numeric_limits<_Tp>::min() * 2;
|
||||
constexpr _Tp __hi = numeric_limits<_Tp>::max() / 2;
|
||||
if (std::abs(__a) <= __hi && std::abs(__b) <= __hi) [[likely]]
|
||||
return (__a + __b) / 2; // always correctly rounded
|
||||
if (std::abs(__a) < __lo) // not safe to halve __a
|
||||
return __a + __b/2;
|
||||
if (std::abs(__b) < __lo) // not safe to halve __b
|
||||
return __a/2 + __b;
|
||||
return __a/2 + __b/2; // otherwise correctly rounded
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -197,12 +213,10 @@ template<typename _Tp>
|
|||
{
|
||||
return __a + (__b - __a) / 2;
|
||||
}
|
||||
#endif // C++20
|
||||
|
||||
_GLIBCXX_END_NAMESPACE_VERSION
|
||||
} // namespace std
|
||||
|
||||
#endif // C++14
|
||||
#endif // C++20
|
||||
|
||||
#if __cplusplus > 201402L
|
||||
#include <bits/stl_function.h>
|
||||
|
|
|
@ -46,9 +46,9 @@ test01()
|
|||
std::gcd<const int&, const int&>(0.1, 0.1); // { dg-error "from here" }
|
||||
}
|
||||
|
||||
// { dg-error "integers" "" { target *-*-* } 133 }
|
||||
// { dg-error "integers" "" { target *-*-* } 134 }
|
||||
// { dg-error "integers" "" { target *-*-* } 135 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 136 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 138 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 135 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 137 }
|
||||
// { dg-prune-output "deleted function" }
|
||||
// { dg-prune-output "invalid operands" }
|
||||
|
|
|
@ -46,9 +46,9 @@ test01()
|
|||
std::lcm<const int&, const int&>(0.1, 0.1); // { dg-error "from here" }
|
||||
}
|
||||
|
||||
// { dg-error "integers" "" { target *-*-* } 147 }
|
||||
// { dg-error "integers" "" { target *-*-* } 148 }
|
||||
// { dg-error "integers" "" { target *-*-* } 149 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 150 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 152 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 149 }
|
||||
// { dg-error "not bools" "" { target *-*-* } 151 }
|
||||
// { dg-prune-output "deleted function" }
|
||||
// { dg-prune-output "invalid operands" }
|
||||
|
|
|
@ -20,6 +20,7 @@
|
|||
|
||||
#include <numeric>
|
||||
#include <limits>
|
||||
#include <cfloat>
|
||||
#include <testsuite_hooks.h>
|
||||
|
||||
void
|
||||
|
@ -57,6 +58,19 @@ test03()
|
|||
VERIFY( std::midpoint(9e9l, -9e9l) == 0.0l );
|
||||
}
|
||||
|
||||
namespace test04
|
||||
{
|
||||
// https://gcc.gnu.org/ml/libstdc++/2019-03/msg00065.html
|
||||
constexpr double d = DBL_MIN + DBL_TRUE_MIN;
|
||||
static_assert( std::midpoint(d, d) == d );
|
||||
|
||||
constexpr float f = FLT_MIN + FLT_TRUE_MIN;
|
||||
static_assert( std::midpoint(f, f) == f );
|
||||
|
||||
constexpr long double l = LDBL_MIN + LDBL_TRUE_MIN;
|
||||
static_assert( std::midpoint(l, l) == l );
|
||||
}
|
||||
|
||||
int main()
|
||||
{
|
||||
test01();
|
||||
|
|
Loading…
Reference in New Issue