14824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 24824e7fdSDimitry Andric // 34824e7fdSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 44824e7fdSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 54824e7fdSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 64824e7fdSDimitry Andric // 74824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 84824e7fdSDimitry Andric 94824e7fdSDimitry Andric #ifndef _LIBCPP___COMPARE_STRONG_ORDER 104824e7fdSDimitry Andric #define _LIBCPP___COMPARE_STRONG_ORDER 114824e7fdSDimitry Andric 124824e7fdSDimitry Andric #include <__bit/bit_cast.h> 134824e7fdSDimitry Andric #include <__compare/compare_three_way.h> 144824e7fdSDimitry Andric #include <__compare/ordering.h> 154824e7fdSDimitry Andric #include <__config> 16bdd1243dSDimitry Andric #include <__type_traits/conditional.h> 17bdd1243dSDimitry Andric #include <__type_traits/decay.h> 184824e7fdSDimitry Andric #include <__utility/forward.h> 194824e7fdSDimitry Andric #include <__utility/priority_tag.h> 204824e7fdSDimitry Andric #include <cmath> 214824e7fdSDimitry Andric #include <cstdint> 224824e7fdSDimitry Andric #include <limits> 234824e7fdSDimitry Andric 244824e7fdSDimitry Andric #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER 254824e7fdSDimitry Andric # pragma GCC system_header 264824e7fdSDimitry Andric #endif 274824e7fdSDimitry Andric 284824e7fdSDimitry Andric _LIBCPP_PUSH_MACROS 294824e7fdSDimitry Andric #include <__undef_macros> 304824e7fdSDimitry Andric 314824e7fdSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 324824e7fdSDimitry Andric 3306c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 344824e7fdSDimitry Andric 354824e7fdSDimitry Andric // [cmp.alg] 364824e7fdSDimitry Andric namespace __strong_order { 374824e7fdSDimitry Andric struct __fn { 38bdd1243dSDimitry Andric // NOLINTBEGIN(libcpp-robust-against-adl) strong_order should use ADL, but only here 394824e7fdSDimitry Andric template <class _Tp, class _Up> 404824e7fdSDimitry Andric requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 41*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<2>) noexcept( 42*cb14a3feSDimitry Andric noexcept(strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))))) 43*cb14a3feSDimitry Andric -> decltype(strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) { 44*cb14a3feSDimitry Andric return strong_ordering(strong_order(std::forward<_Tp>(__t), std::forward<_Up>(__u))); 45*cb14a3feSDimitry Andric } 46bdd1243dSDimitry Andric // NOLINTEND(libcpp-robust-against-adl) 474824e7fdSDimitry Andric 484824e7fdSDimitry Andric template <class _Tp, class _Up, class _Dp = decay_t<_Tp>> 494824e7fdSDimitry Andric requires is_same_v<_Dp, decay_t<_Up>> && is_floating_point_v<_Dp> __go__fn50*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI static constexpr strong_ordering __go(_Tp&& __t, _Up&& __u, __priority_tag<1>) noexcept { 514824e7fdSDimitry Andric if constexpr (numeric_limits<_Dp>::is_iec559 && sizeof(_Dp) == sizeof(int32_t)) { 525f757f3fSDimitry Andric int32_t __rx = std::bit_cast<int32_t>(__t); 535f757f3fSDimitry Andric int32_t __ry = std::bit_cast<int32_t>(__u); 544824e7fdSDimitry Andric __rx = (__rx < 0) ? (numeric_limits<int32_t>::min() - __rx - 1) : __rx; 554824e7fdSDimitry Andric __ry = (__ry < 0) ? (numeric_limits<int32_t>::min() - __ry - 1) : __ry; 564824e7fdSDimitry Andric return (__rx <=> __ry); 574824e7fdSDimitry Andric } else if constexpr (numeric_limits<_Dp>::is_iec559 && sizeof(_Dp) == sizeof(int64_t)) { 585f757f3fSDimitry Andric int64_t __rx = std::bit_cast<int64_t>(__t); 595f757f3fSDimitry Andric int64_t __ry = std::bit_cast<int64_t>(__u); 604824e7fdSDimitry Andric __rx = (__rx < 0) ? (numeric_limits<int64_t>::min() - __rx - 1) : __rx; 614824e7fdSDimitry Andric __ry = (__ry < 0) ? (numeric_limits<int64_t>::min() - __ry - 1) : __ry; 624824e7fdSDimitry Andric return (__rx <=> __ry); 634824e7fdSDimitry Andric } else if (__t < __u) { 644824e7fdSDimitry Andric return strong_ordering::less; 654824e7fdSDimitry Andric } else if (__t > __u) { 664824e7fdSDimitry Andric return strong_ordering::greater; 674824e7fdSDimitry Andric } else if (__t == __u) { 684824e7fdSDimitry Andric if constexpr (numeric_limits<_Dp>::radix == 2) { 695f757f3fSDimitry Andric return std::signbit(__u) <=> std::signbit(__t); 704824e7fdSDimitry Andric } else { 714824e7fdSDimitry Andric // This is bullet 3 of the IEEE754 algorithm, relevant 724824e7fdSDimitry Andric // only for decimal floating-point; 734824e7fdSDimitry Andric // see https://stackoverflow.com/questions/69068075/ 745f757f3fSDimitry Andric if (__t == 0 || std::isinf(__t)) { 755f757f3fSDimitry Andric return std::signbit(__u) <=> std::signbit(__t); 764824e7fdSDimitry Andric } else { 774824e7fdSDimitry Andric int __texp, __uexp; 785f757f3fSDimitry Andric (void)std::frexp(__t, &__texp); 795f757f3fSDimitry Andric (void)std::frexp(__u, &__uexp); 804824e7fdSDimitry Andric return (__t < 0) ? (__texp <=> __uexp) : (__uexp <=> __texp); 814824e7fdSDimitry Andric } 824824e7fdSDimitry Andric } 834824e7fdSDimitry Andric } else { 844824e7fdSDimitry Andric // They're unordered, so one of them must be a NAN. 854824e7fdSDimitry Andric // The order is -QNAN, -SNAN, numbers, +SNAN, +QNAN. 865f757f3fSDimitry Andric bool __t_is_nan = std::isnan(__t); 875f757f3fSDimitry Andric bool __u_is_nan = std::isnan(__u); 885f757f3fSDimitry Andric bool __t_is_negative = std::signbit(__t); 895f757f3fSDimitry Andric bool __u_is_negative = std::signbit(__u); 90*cb14a3feSDimitry Andric using _IntType = 91*cb14a3feSDimitry Andric conditional_t< sizeof(__t) == sizeof(int32_t), 92*cb14a3feSDimitry Andric int32_t, 93*cb14a3feSDimitry Andric conditional_t< sizeof(__t) == sizeof(int64_t), int64_t, void> >; 940eae32dcSDimitry Andric if constexpr (is_same_v<_IntType, void>) { 954824e7fdSDimitry Andric static_assert(sizeof(_Dp) == 0, "std::strong_order is unimplemented for this floating-point type"); 964824e7fdSDimitry Andric } else if (__t_is_nan && __u_is_nan) { 974824e7fdSDimitry Andric // Order by sign bit, then by "payload bits" (we'll just use bit_cast). 984824e7fdSDimitry Andric if (__t_is_negative != __u_is_negative) { 994824e7fdSDimitry Andric return (__u_is_negative <=> __t_is_negative); 1004824e7fdSDimitry Andric } else { 1015f757f3fSDimitry Andric return std::bit_cast<_IntType>(__t) <=> std::bit_cast<_IntType>(__u); 1024824e7fdSDimitry Andric } 1034824e7fdSDimitry Andric } else if (__t_is_nan) { 1044824e7fdSDimitry Andric return __t_is_negative ? strong_ordering::less : strong_ordering::greater; 1054824e7fdSDimitry Andric } else { 1064824e7fdSDimitry Andric return __u_is_negative ? strong_ordering::greater : strong_ordering::less; 1074824e7fdSDimitry Andric } 1084824e7fdSDimitry Andric } 1094824e7fdSDimitry Andric } 1104824e7fdSDimitry Andric 1114824e7fdSDimitry Andric template <class _Tp, class _Up> 1124824e7fdSDimitry Andric requires is_same_v<decay_t<_Tp>, decay_t<_Up>> 113*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI static constexpr auto __go(_Tp&& __t, _Up&& __u, __priority_tag<0>) noexcept( 114*cb14a3feSDimitry Andric noexcept(strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u))))) 115*cb14a3feSDimitry Andric -> decltype(strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) { 116*cb14a3feSDimitry Andric return strong_ordering(compare_three_way()(std::forward<_Tp>(__t), std::forward<_Up>(__u))); 117*cb14a3feSDimitry Andric } 1184824e7fdSDimitry Andric 1194824e7fdSDimitry Andric template <class _Tp, class _Up> 1204824e7fdSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t, _Up&& __u) const 1215f757f3fSDimitry Andric noexcept(noexcept(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>()))) 122*cb14a3feSDimitry Andric -> decltype(__go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>())) { 123*cb14a3feSDimitry Andric return __go(std::forward<_Tp>(__t), std::forward<_Up>(__u), __priority_tag<2>()); 124*cb14a3feSDimitry Andric } 1254824e7fdSDimitry Andric }; 1264824e7fdSDimitry Andric } // namespace __strong_order 1274824e7fdSDimitry Andric 1284824e7fdSDimitry Andric inline namespace __cpo { 1294824e7fdSDimitry Andric inline constexpr auto strong_order = __strong_order::__fn{}; 1304824e7fdSDimitry Andric } // namespace __cpo 1314824e7fdSDimitry Andric 13206c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 1334824e7fdSDimitry Andric 1344824e7fdSDimitry Andric _LIBCPP_END_NAMESPACE_STD 1354824e7fdSDimitry Andric 1364824e7fdSDimitry Andric _LIBCPP_POP_MACROS 1374824e7fdSDimitry Andric 1384824e7fdSDimitry Andric #endif // _LIBCPP___COMPARE_STRONG_ORDER 139