// <experimental/memory_resource> -*- C++ -*-
-// Copyright (C) 2015 Free Software Foundation, Inc.
+// Copyright (C) 2015-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
/** @file experimental/memory_resource
* This is a TS C++ Library header.
+ * @ingroup libfund-ts
*/
#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
#define _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE 1
-#include <memory>
-#include <new>
-#include <atomic>
-#include <cstddef>
-#include <bits/alloc_traits.h>
+#pragma GCC system_header
+
+#include <bits/requires_hosted.h> // experimental is currently omitted
+
+#if __cplusplus >= 201402L
+
+#include <memory> // align, uses_allocator, __uses_alloc
+#include <experimental/utility> // pair, experimental::erased_type
+#include <tuple> // tuple, forward_as_tuple
+#include <atomic> // atomic
+#include <new> // placement new
+#include <cstddef> // max_align_t
+#include <bits/new_allocator.h>
+#include <debug/assertions.h>
+
+namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+ template<typename _Tp> class malloc_allocator;
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace __gnu_cxx
namespace std {
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
namespace experimental {
inline namespace fundamentals_v2 {
namespace pmr {
-_GLIBCXX_BEGIN_NAMESPACE_VERSION
+#define __cpp_lib_experimental_memory_resources 201402L
+
+ // Standard memory resources
+ // 8.5 Class memory_resource
class memory_resource;
- template <typename _Tp>
+ // 8.6 Class template polymorphic_allocator
+ template<typename _Tp>
class polymorphic_allocator;
- template <typename _Alloc>
+ template<typename _Alloc, typename _Resource = memory_resource>
class __resource_adaptor_imp;
- template <typename _Alloc>
+ // 8.7 Alias template resource_adaptor
+ template<typename _Alloc>
using resource_adaptor = __resource_adaptor_imp<
typename allocator_traits<_Alloc>::template rebind_alloc<char>>;
- template <typename _Tp>
- struct __uses_allocator_construction_helper;
-
- // Global memory resources
+ // 8.8 Global memory resources
memory_resource* new_delete_resource() noexcept;
memory_resource* null_memory_resource() noexcept;
-
- // The default memory resource
memory_resource* get_default_resource() noexcept;
memory_resource* set_default_resource(memory_resource* __r) noexcept;
- // Standard memory resources
+ // TODO 8.9 Pool resource classes
- // 8.5 Class memory_resource
class memory_resource
{
static constexpr size_t _S_max_align = alignof(max_align_t);
public:
- virtual ~memory_resource() { }
+ memory_resource() = default;
+ memory_resource(const memory_resource&) = default;
+ virtual ~memory_resource() = default;
- void*
+ memory_resource& operator=(const memory_resource&) = default;
+
+ _GLIBCXX_NODISCARD void*
allocate(size_t __bytes, size_t __alignment = _S_max_align)
{ return do_allocate(__bytes, __alignment); }
};
inline bool
- operator==(const memory_resource& __a,
- const memory_resource& __b) noexcept
+ operator==(const memory_resource& __a, const memory_resource& __b) noexcept
{ return &__a == &__b || __a.is_equal(__b); }
inline bool
- operator!=(const memory_resource& __a,
- const memory_resource& __b) noexcept
+ operator!=(const memory_resource& __a, const memory_resource& __b) noexcept
{ return !(__a == __b); }
- // 8.6 Class template polymorphic_allocator
- template <class _Tp>
+ template<typename _Tp>
class polymorphic_allocator
{
- using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
- using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
-
- template<typename _Tp1, typename... _Args>
- void
- _M_construct(__uses_alloc0, _Tp1* __p, _Args&&... __args)
- { ::new(__p) _Tp1(std::forward<_Args>(__args)...); }
-
- template<typename _Tp1, typename... _Args>
- void
- _M_construct(__uses_alloc1_, _Tp1* __p, _Args&&... __args)
- { ::new(__p) _Tp1(allocator_arg, this->resource(),
- std::forward<_Args>(__args)...); }
-
- template<typename _Tp1, typename... _Args>
- void
- _M_construct(__uses_alloc2_, _Tp1* __p, _Args&&... __args)
- { ::new(__p) _Tp1(std::forward<_Args>(__args)...,
- this->resource()); }
-
public:
using value_type = _Tp;
polymorphic_allocator&
operator=(const polymorphic_allocator& __rhs) = default;
- _Tp* allocate(size_t __n)
+ _GLIBCXX_NODISCARD _Tp* allocate(size_t __n)
{ return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp),
alignof(_Tp))); }
- void deallocate(_Tp* __p, size_t __n)
+ void
+ deallocate(_Tp* __p, size_t __n)
{ _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); }
template <typename _Tp1, typename... _Args> //used here
- void construct(_Tp1* __p, _Args&&... __args)
+ void
+ construct(_Tp1* __p, _Args&&... __args)
{
- auto __use_tag = __use_alloc<_Tp1, memory_resource*,
- _Args...>(this->resource());
- _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
+ std::__uses_allocator_construct(this->resource(), __p,
+ std::forward<_Args>(__args)...);
}
// Specializations for pair using piecewise construction
template <typename _Tp1, typename _Tp2,
typename... _Args1, typename... _Args2>
- void construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
- tuple<_Args1...> __x,
- tuple<_Args2...> __y)
+ void
+ construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t,
+ tuple<_Args1...> __x, tuple<_Args2...> __y)
{
+ memory_resource* const __resource = this->resource();
auto __x_use_tag =
- __use_alloc<_Tp1, memory_resource*, _Args1...>(this->resource());
+ std::__use_alloc<_Tp1, memory_resource*, _Args1...>(__resource);
auto __y_use_tag =
- __use_alloc<_Tp2, memory_resource*, _Args2...>(this->resource());
+ std::__use_alloc<_Tp2, memory_resource*, _Args2...>(__resource);
::new(__p) std::pair<_Tp1, _Tp2>(piecewise_construct,
_M_construct_p(__x_use_tag, __x),
}
template <typename _Tp1, typename _Tp2>
- void construct(pair<_Tp1,_Tp2>* __p)
+ void
+ construct(pair<_Tp1,_Tp2>* __p)
{ this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
- void construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
- { this->construct(__p, piecewise_construct,
- forward_as_tuple(std::forward<_Up>(__x)),
- forward_as_tuple(std::forward<_Vp>(__y))); }
+ void
+ construct(pair<_Tp1,_Tp2>* __p, _Up&& __x, _Vp&& __y)
+ {
+ this->construct(__p, piecewise_construct,
+ std::forward_as_tuple(std::forward<_Up>(__x)),
+ std::forward_as_tuple(std::forward<_Vp>(__y)));
+ }
template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
- void construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
- { this->construct(__p, piecewise_construct, forward_as_tuple(__pr.first),
- forward_as_tuple(__pr.second)); }
+ void
+ construct(pair<_Tp1,_Tp2>* __p, const std::pair<_Up, _Vp>& __pr)
+ {
+ this->construct(__p, piecewise_construct,
+ std::forward_as_tuple(__pr.first),
+ std::forward_as_tuple(__pr.second));
+ }
template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp>
- void construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
- { this->construct(__p, piecewise_construct,
- forward_as_tuple(std::forward<_Up>(__pr.first)),
- forward_as_tuple(std::forward<_Vp>(__pr.second))); }
+ void
+ construct(pair<_Tp1,_Tp2>* __p, pair<_Up, _Vp>&& __pr)
+ {
+ this->construct(__p, piecewise_construct,
+ std::forward_as_tuple(std::forward<_Up>(__pr.first)),
+ std::forward_as_tuple(std::forward<_Vp>(__pr.second)));
+ }
template <typename _Up>
- void destroy(_Up* __p)
+ void
+ destroy(_Up* __p)
{ __p->~_Up(); }
// Return a default-constructed allocator (no allocator propagation)
- polymorphic_allocator select_on_container_copy_construction() const
+ polymorphic_allocator
+ select_on_container_copy_construction() const
{ return polymorphic_allocator(); }
- memory_resource* resource() const
- { return _M_resource; }
+ memory_resource* resource() const { return _M_resource; }
private:
+ using __uses_alloc1_ = __uses_alloc1<memory_resource*>;
+ using __uses_alloc2_ = __uses_alloc2<memory_resource*>;
+
template<typename _Tuple>
_Tuple&&
_M_construct_p(__uses_alloc0, _Tuple& __t)
};
template <class _Tp1, class _Tp2>
- bool operator==(const polymorphic_allocator<_Tp1>& __a,
- const polymorphic_allocator<_Tp2>& __b) noexcept
+ bool
+ operator==(const polymorphic_allocator<_Tp1>& __a,
+ const polymorphic_allocator<_Tp2>& __b) noexcept
{ return *__a.resource() == *__b.resource(); }
template <class _Tp1, class _Tp2>
- bool operator!=(const polymorphic_allocator<_Tp1>& __a,
- const polymorphic_allocator<_Tp2>& __b) noexcept
+ bool
+ operator!=(const polymorphic_allocator<_Tp1>& __a,
+ const polymorphic_allocator<_Tp2>& __b) noexcept
{ return !(__a == __b); }
+
+ /// @cond undocumented
+ class __resource_adaptor_common
+ {
+ template<typename, typename> friend class __resource_adaptor_imp;
+
+ struct _AlignMgr
+ {
+ _AlignMgr(size_t __nbytes, size_t __align)
+ : _M_nbytes(__nbytes), _M_align(__align)
+ { }
+
+ // Total size that needs to be allocated.
+ size_t
+ _M_alloc_size() const { return _M_buf_size() + _M_token_size(); }
+
+ void*
+ _M_adjust(void* __ptr) const
+ {
+ const auto __orig_ptr = static_cast<char*>(__ptr);
+ size_t __space = _M_buf_size();
+ // Align the pointer within the buffer:
+ std::align(_M_align, _M_nbytes, __ptr, __space);
+ const auto __aligned_ptr = static_cast<char*>(__ptr);
+ const auto __token_size = _M_token_size();
+ // Store token immediately after the aligned block:
+ char* const __end = __aligned_ptr + _M_nbytes;
+ if (__token_size == 1)
+ _S_write<unsigned char>(__end, __aligned_ptr - __orig_ptr);
+ else if (__token_size == sizeof(short))
+ _S_write<unsigned short>(__end, __aligned_ptr - __orig_ptr);
+ else if (__token_size == sizeof(int) && sizeof(int) < sizeof(char*))
+ _S_write<unsigned int>(__end, __aligned_ptr - __orig_ptr);
+ else // (__token_size == sizeof(char*))
+ // Just store the original pointer:
+ _S_write<char*>(__end, __orig_ptr);
+ return __aligned_ptr;
+ }
+
+ char*
+ _M_unadjust(char* __ptr) const
+ {
+ const char* const __end = __ptr + _M_nbytes;
+ char* __orig_ptr;
+ const auto __token_size = _M_token_size();
+ // Read the token and restore the original pointer:
+ if (__token_size == 1)
+ __orig_ptr = __ptr - _S_read<unsigned char>(__end);
+ else if (__token_size == sizeof(short))
+ __orig_ptr = __ptr - _S_read<unsigned short>(__end);
+ else if (__token_size == sizeof(int)
+ && sizeof(int) < sizeof(char*))
+ __orig_ptr = __ptr - _S_read<unsigned int>(__end);
+ else // (__token_size == sizeof(char*))
+ __orig_ptr = _S_read<char*>(__end);
+ // The adjustment is always less than the requested alignment,
+ // so if that isn't true now then either the wrong size was passed
+ // to deallocate or the token was overwritten by a buffer overflow:
+ __glibcxx_assert(static_cast<size_t>(__ptr - __orig_ptr) < _M_align);
+ return __orig_ptr;
+ }
+
+ private:
+ size_t _M_nbytes;
+ size_t _M_align;
+
+ // Number of bytes needed to fit block of given size and alignment.
+ size_t
+ _M_buf_size() const { return _M_nbytes + _M_align - 1; }
+
+ // Number of additional bytes needed to write the token.
+ int
+ _M_token_size() const
+ {
+ if (_M_align <= (1ul << __CHAR_BIT__))
+ return 1;
+ if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__)))
+ return sizeof(short);
+ if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__)))
+ return sizeof(int);
+ return sizeof(char*);
+ }
+
+ template<typename _Tp>
+ static void
+ _S_write(void* __to, _Tp __val)
+ { __builtin_memcpy(__to, &__val, sizeof(_Tp)); }
+
+ template<typename _Tp>
+ static _Tp
+ _S_read(const void* __from)
+ {
+ _Tp __val;
+ __builtin_memcpy(&__val, __from, sizeof(_Tp));
+ return __val;
+ }
+ };
+ };
+ /// @endcond
+
// 8.7.1 __resource_adaptor_imp
- template <typename _Alloc>
- class __resource_adaptor_imp : public memory_resource
+ template<typename _Alloc, typename _Resource>
+ class __resource_adaptor_imp
+ : public _Resource, private __resource_adaptor_common
{
+ using memory_resource = _Resource;
+
+ static_assert(is_same<char,
+ typename allocator_traits<_Alloc>::value_type>::value,
+ "Allocator's value_type is char");
+ static_assert(is_same<char*,
+ typename allocator_traits<_Alloc>::pointer>::value,
+ "Allocator's pointer type is value_type*");
+ static_assert(is_same<const char*,
+ typename allocator_traits<_Alloc>::const_pointer>::value,
+ "Allocator's const_pointer type is value_type const*");
+ static_assert(is_same<void*,
+ typename allocator_traits<_Alloc>::void_pointer>::value,
+ "Allocator's void_pointer type is void*");
+ static_assert(is_same<const void*,
+ typename allocator_traits<_Alloc>::const_void_pointer>::value,
+ "Allocator's const_void_pointer type is void const*");
+
public:
using allocator_type = _Alloc;
__resource_adaptor_imp&
operator=(const __resource_adaptor_imp&) = default;
- allocator_type get_allocator() const { return _M_alloc; }
+ allocator_type get_allocator() const noexcept { return _M_alloc; }
protected:
+#if (defined __sun__ || defined __VXWORKS__) && defined __i386__
+// Cannot use max_align_t on 32-bit Solaris x86, see PR libstdc++/77691
+# define _GLIBCXX_MAX_ALIGN_MATCHES_MALLOC 0
+#elif defined __hpux__ && defined __hppa__ && defined __LP64__
+// Ignore inconsistent long double and malloc alignment (libstdc++/77691)
+# define _GLIBCXX_MAX_ALIGN_MATCHES_MALLOC 0
+#else
+# define _GLIBCXX_MAX_ALIGN_MATCHES_MALLOC 1
+#endif
+
virtual void*
- do_allocate(size_t __bytes, size_t __alignment)
+ do_allocate(size_t __bytes, size_t __alignment) override
{
- using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
- size_t __new_size = _S_aligned_size(__bytes,
- _S_supported(__alignment) ?
- __alignment : _S_max_align);
- return _Aligned_alloc().allocate(__new_size);
+#if _GLIBCXX_MAX_ALIGN_MATCHES_MALLOC
+ if (__alignment == alignof(max_align_t))
+ return _M_allocate<alignof(max_align_t)>(__bytes);
+#endif
+ switch (__alignment)
+ {
+ case 1:
+ return _M_alloc.allocate(__bytes);
+ case 2:
+ return _M_allocate<2>(__bytes);
+ case 4:
+ return _M_allocate<4>(__bytes);
+ case 8:
+ return _M_allocate<8>(__bytes);
+ }
+ const _AlignMgr __mgr(__bytes, __alignment);
+ // Assume _M_alloc returns 1-byte aligned memory, so allocate enough
+ // space to fit a block of the right size and alignment, plus some
+ // extra bytes to store a token for retrieving the original pointer.
+ return __mgr._M_adjust(_M_alloc.allocate(__mgr._M_alloc_size()));
}
virtual void
- do_deallocate(void* __p, size_t __bytes, size_t __alignment)
+ do_deallocate(void* __ptr, size_t __bytes, size_t __alignment) noexcept
+ override
{
- using _Aligned_alloc = std::__alloc_rebind<_Alloc, char>;
- size_t __new_size = _S_aligned_size(__bytes,
- _S_supported(__alignment) ?
- __alignment : _S_max_align);
- _Aligned_alloc().deallocate(static_cast<typename
- _Aligned_alloc::pointer>(__p),
- __new_size);
+#if _GLIBCXX_MAX_ALIGN_MATCHES_MALLOC
+ if (__alignment == alignof(max_align_t))
+ return (void) _M_deallocate<alignof(max_align_t)>(__ptr, __bytes);
+#endif
+ switch (__alignment)
+ {
+ case 1:
+ return (void) _M_alloc.deallocate((char*)__ptr, __bytes);
+ case 2:
+ return (void) _M_deallocate<2>(__ptr, __bytes);
+ case 4:
+ return (void) _M_deallocate<4>(__ptr, __bytes);
+ case 8:
+ return (void) _M_deallocate<8>(__ptr, __bytes);
+ }
+ const _AlignMgr __mgr(__bytes, __alignment);
+ // Use the stored token to retrieve the original pointer.
+ _M_alloc.deallocate(__mgr._M_unadjust((char*)__ptr),
+ __mgr._M_alloc_size());
}
virtual bool
- do_is_equal(const memory_resource& __other) const noexcept
+ do_is_equal(const memory_resource& __other) const noexcept override
{
- auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other);
- return __p ? (_M_alloc == __p->_M_alloc) : false;
+#if __cpp_rtti
+ if (auto __p = dynamic_cast<const __resource_adaptor_imp*>(&__other))
+ return _M_alloc == __p->_M_alloc;
+#else
+ if (this == &__other) // Need RTTI to do better than this.
+ return true;
+#endif
+ return false;
}
private:
- // Calculate Aligned Size
- // Returns a size that is larger than or equal to __size and divided by
- // __alignment, where __alignment is required to be the power of 2.
- static size_t
- _S_aligned_size(size_t __size, size_t __alignment)
- { return ((__size - 1)|(__alignment - 1)) + 1; }
-
- // Determine whether alignment meets one of those preconditions:
- // 1. Equals to Zero
- // 2. Is power of two
- static bool
- _S_supported (size_t __x)
- { return ((__x != 0) && !(__x & (__x - 1))); }
-
- _Alloc _M_alloc;
+ template<size_t _Num>
+ struct _Aligned_type { alignas(_Num) char __c[_Num]; };
+
+ // Rebind the allocator to the specified type and use it to allocate.
+ template<size_t _Num, typename _Tp = _Aligned_type<_Num>>
+ void*
+ _M_allocate(size_t __bytes)
+ {
+ typename allocator_traits<_Alloc>::template
+ rebind_alloc<_Tp> __a2(_M_alloc);
+ const size_t __n = (__bytes + _Num - 1) / _Num;
+ return __a2.allocate(__n);
+ }
+
+ // Rebind the allocator to the specified type and use it to deallocate.
+ template<size_t _Num, typename _Tp = _Aligned_type<_Num>>
+ void
+ _M_deallocate(void* __ptr, size_t __bytes) noexcept
+ {
+ typename allocator_traits<_Alloc>::template
+ rebind_alloc<_Tp> __a2(_M_alloc);
+ const size_t __n = (__bytes + _Num - 1) / _Num;
+ __a2.deallocate((_Tp*)__ptr, __n);
+ }
+
+ _Alloc _M_alloc{};
};
// Global memory resources
- inline std::atomic<memory_resource*>&
- __get_default_resource()
- {
- static atomic<memory_resource*> _S_default_resource(new_delete_resource());
- return _S_default_resource;
- }
inline memory_resource*
new_delete_resource() noexcept
{
- static resource_adaptor<std::allocator<char>> __r;
- return static_cast<memory_resource*>(&__r);
+ using type = resource_adaptor<std::__new_allocator<char>>;
+ alignas(type) static unsigned char __buf[sizeof(type)];
+ static type* __r = new(__buf) type;
+ return __r;
}
- template <typename _Alloc>
- class __null_memory_resource : private memory_resource
+ inline memory_resource*
+ null_memory_resource() noexcept
+ {
+ class type final : public memory_resource
{
- protected:
void*
- do_allocate(size_t __bytes, size_t __alignment)
+ do_allocate(size_t, size_t) override
{ std::__throw_bad_alloc(); }
void
- do_deallocate(void* __p, size_t __bytes, size_t __alignment)
+ do_deallocate(void*, size_t, size_t) noexcept override
{ }
bool
- do_is_equal(const memory_resource& __other) const noexcept
- { }
-
- friend memory_resource* null_memory_resource() noexcept;
+ do_is_equal(const memory_resource& __other) const noexcept override
+ { return this == &__other; }
};
- inline memory_resource*
- null_memory_resource() noexcept
- {
- static __null_memory_resource<void> __r;
- return static_cast<memory_resource*>(&__r);
+ alignas(type) static unsigned char __buf[sizeof(type)];
+ static type* __r = new(__buf) type;
+ return __r;
}
// The default memory resource
+
+ /// @cond undocumented
+ inline auto&
+ __get_default_resource()
+ {
+#ifndef _GLIBCXX_HAS_GTHREADS
+ struct type {
+ using value_type = memory_resource*;
+ explicit type(value_type __r) : _M_r(__r) { }
+ value_type _M_r;
+ value_type load() const { return _M_r; }
+ value_type exchange(value_type __r) { return std::__exchange(_M_r, __r); }
+ };
+#else
+ using type = atomic<memory_resource*>;
+#endif
+ alignas(type) static unsigned char __buf[sizeof(type)];
+ static type* __r = new(__buf) type(new_delete_resource());
+ return *__r;
+ }
+ /// @endcond
+
+ /// Get the current default resource.
inline memory_resource*
get_default_resource() noexcept
{ return __get_default_resource().load(); }
+ /// Change the default resource and return the previous one.
inline memory_resource*
set_default_resource(memory_resource* __r) noexcept
{
return __get_default_resource().exchange(__r);
}
-_GLIBCXX_END_NAMESPACE_VERSION
} // namespace pmr
} // namespace fundamentals_v2
} // namespace experimental
-} // namespace std
-#endif
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+#endif // C++14
+#endif // _GLIBCXX_EXPERIMENTAL_MEMORY_RESOURCE
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