Author: Nikolas Klauser Date: 2025-02-18T21:56:43-08:00 New Revision: 04295354b0f0f101773c4f9437680d45a70bab24
URL: https://github.com/llvm/llvm-project/commit/04295354b0f0f101773c4f9437680d45a70bab24 DIFF: https://github.com/llvm/llvm-project/commit/04295354b0f0f101773c4f9437680d45a70bab24.diff LOG: Revert "[libc++] Reduce std::conjunction overhead (#124259)" It turns out that the new implementation takes significantly more stack memory for some reason. This reverts commit 2696e4fb9567d23ce065a067e7f4909b310daf50. (cherry picked from commit 0227396417d4625bc93affdd8957ff8d90c76299) Added: Modified: libcxx/include/__type_traits/conjunction.h Removed: ################################################################################ diff --git a/libcxx/include/__type_traits/conjunction.h b/libcxx/include/__type_traits/conjunction.h index 6b6717a50a468..ad9656acd47ec 100644 --- a/libcxx/include/__type_traits/conjunction.h +++ b/libcxx/include/__type_traits/conjunction.h @@ -10,6 +10,8 @@ #define _LIBCPP___TYPE_TRAITS_CONJUNCTION_H #include <__config> +#include <__type_traits/conditional.h> +#include <__type_traits/enable_if.h> #include <__type_traits/integral_constant.h> #include <__type_traits/is_same.h> @@ -19,29 +21,22 @@ _LIBCPP_BEGIN_NAMESPACE_STD -template <bool> -struct _AndImpl; +template <class...> +using __expand_to_true _LIBCPP_NODEBUG = true_type; -template <> -struct _AndImpl<true> { - template <class _Res, class _First, class... _Rest> - using _Result _LIBCPP_NODEBUG = - typename _AndImpl<bool(_First::value) && sizeof...(_Rest) != 0>::template _Result<_First, _Rest...>; -}; +template <class... _Pred> +__expand_to_true<__enable_if_t<_Pred::value>...> __and_helper(int); -template <> -struct _AndImpl<false> { - template <class _Res, class...> - using _Result _LIBCPP_NODEBUG = _Res; -}; +template <class...> +false_type __and_helper(...); // _And always performs lazy evaluation of its arguments. // // However, `_And<_Pred...>` itself will evaluate its result immediately (without having to // be instantiated) since it is an alias, unlike `conjunction<_Pred...>`, which is a struct. // If you want to defer the evaluation of `_And<_Pred...>` itself, use `_Lazy<_And, _Pred...>`. -template <class... _Args> -using _And _LIBCPP_NODEBUG = typename _AndImpl<sizeof...(_Args) != 0>::template _Result<true_type, _Args...>; +template <class... _Pred> +using _And _LIBCPP_NODEBUG = decltype(std::__and_helper<_Pred...>(0)); template <bool... _Preds> struct __all_dummy; @@ -51,11 +46,22 @@ struct __all : _IsSame<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)... #if _LIBCPP_STD_VER >= 17 -template <class... _Args> -struct _LIBCPP_NO_SPECIALIZATIONS conjunction : _And<_Args...> {}; +template <class...> +struct _LIBCPP_NO_SPECIALIZATIONS conjunction : true_type {}; + +_LIBCPP_DIAGNOSTIC_PUSH +# if __has_warning("-Winvalid-specialization") +_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-specialization") +# endif +template <class _Arg> +struct conjunction<_Arg> : _Arg {}; + +template <class _Arg, class... _Args> +struct conjunction<_Arg, _Args...> : conditional_t<!bool(_Arg::value), _Arg, conjunction<_Args...>> {}; +_LIBCPP_DIAGNOSTIC_POP template <class... _Args> -_LIBCPP_NO_SPECIALIZATIONS inline constexpr bool conjunction_v = _And<_Args...>::value; +_LIBCPP_NO_SPECIALIZATIONS inline constexpr bool conjunction_v = conjunction<_Args...>::value; #endif // _LIBCPP_STD_VER >= 17 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
