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 <cstddef>
  15 #include <new>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_BEGIN_NAMESPACE_STD
  22
  23 // __builtin_new_allocator -- A non-templated helper for allocating and
  24 // deallocating memory using __builtin_operator_new and
  25 // __builtin_operator_delete. It should be used in preference to
  26 // `std::allocator<T>` to avoid additional instantiations.
  27 struct __builtin_new_allocator {
  28   struct __builtin_new_deleter {
  29     typedef void* pointer_type;
  30
  31     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __builtin_new_deleter(size_t __size, size_t __align)
  32         : __size_(__size), __align_(__align) {}
  33
  34     _LIBCPP_HIDE_FROM_ABI void operator()(void* __p) const _NOEXCEPT {
  35         _VSTD::__libcpp_deallocate(__p, __size_, __align_);
  36     }
  37
  38    private:
  39     size_t __size_;
  40     size_t __align_;
  41   };
  42
  43   typedef unique_ptr<void, __builtin_new_deleter> __holder_t;
  44
  45   _LIBCPP_HIDE_FROM_ABI static __holder_t __allocate_bytes(size_t __s, size_t __align) {
  46       return __holder_t(_VSTD::__libcpp_allocate(__s, __align),
  47                      __builtin_new_deleter(__s, __align));
  48   }
  49
  50   _LIBCPP_HIDE_FROM_ABI static void __deallocate_bytes(void* __p, size_t __s,
  51                                  size_t __align) _NOEXCEPT {
  52       _VSTD::__libcpp_deallocate(__p, __s, __align);
  53   }
  54
  55   template <class _Tp>
  56   _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE
  57   _LIBCPP_HIDE_FROM_ABI static __holder_t __allocate_type(size_t __n) {
  58       return __allocate_bytes(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
  59   }
  60
  61   template <class _Tp>
  62   _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE
  63   _LIBCPP_HIDE_FROM_ABI static void __deallocate_type(void* __p, size_t __n) _NOEXCEPT {
  64       __deallocate_bytes(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
  65   }
  66 };
  67
  68 _LIBCPP_END_NAMESPACE_STD
  69
  70 #endif // _LIBCPP___MEMORY_BUILTIN_NEW_ALLOCATOR_H