libcxx/include/__memory/builtin_new_allocator.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___MEMORY_BUILTIN_NEW_ALLOCATOR_H
  10 #define _LIBCPP___MEMORY_BUILTIN_NEW_ALLOCATOR_H
  11
  12 #include <__config>
  13 #include <__memory/unique_ptr.h>
  14 #include <new>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 // __builtin_new_allocator -- A non-templated helper for allocating and
  23 // deallocating memory using __builtin_operator_new and
  24 // __builtin_operator_delete. It should be used in preference to
  25 // `std::allocator<T>` to avoid additional instantiations.
  26 struct __builtin_new_allocator {
  27   struct __builtin_new_deleter {
  28     typedef void* pointer_type;
  29
  30     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __builtin_new_deleter(size_t __size, size_t __align)
  31         : __size_(__size), __align_(__align) {}
  32
  33     _LIBCPP_HIDE_FROM_ABI void operator()(void* __p) const _NOEXCEPT {
  34       std::__libcpp_deallocate(__p, __size_, __align_);
  35     }
  36
  37   private:
  38     size_t __size_;
  39     size_t __align_;
  40   };
  41
  42   typedef unique_ptr<void, __builtin_new_deleter> __holder_t;
  43
  44   _LIBCPP_HIDE_FROM_ABI static __holder_t __allocate_bytes(size_t __s, size_t __align) {
  45     return __holder_t(std::__libcpp_allocate(__s, __align), __builtin_new_deleter(__s, __align));
  46   }
  47
  48   _LIBCPP_HIDE_FROM_ABI static void __deallocate_bytes(void* __p, size_t __s, size_t __align) _NOEXCEPT {
  49     std::__libcpp_deallocate(__p, __s, __align);
  50   }
  51
  52   template <class _Tp>
  53   _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI static __holder_t __allocate_type(size_t __n) {
  54     return __allocate_bytes(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
  55   }
  56
  57   template <class _Tp>
  58   _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI static void
  59   __deallocate_type(void* __p, size_t __n) _NOEXCEPT {
  60     __deallocate_bytes(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
  61   }
  62 };
  63
  64 _LIBCPP_END_NAMESPACE_STD
  65
  66 #endif // _LIBCPP___MEMORY_BUILTIN_NEW_ALLOCATOR_H