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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include <experimental/memory_resource>
#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
# include <atomic>
#elif !defined(_LIBCPP_HAS_NO_THREADS)
# include <mutex>
# if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
# pragma comment(lib, "pthread")
# endif
#endif
_LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
// memory_resource
//memory_resource::~memory_resource() {}
// new_delete_resource()
class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
: public memory_resource
{
void *do_allocate(size_t size, size_t align) override {
#ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
if (__is_overaligned_for_new(align))
__throw_bad_alloc();
#endif
return _VSTD::__libcpp_allocate(size, align);
}
void do_deallocate(void *p, size_t n, size_t align) override {
_VSTD::__libcpp_deallocate(p, n, align);
}
bool do_is_equal(memory_resource const & other) const noexcept override
{ return &other == this; }
public:
~__new_delete_memory_resource_imp() override = default;
};
// null_memory_resource()
class _LIBCPP_TYPE_VIS __null_memory_resource_imp
: public memory_resource
{
public:
~__null_memory_resource_imp() = default;
protected:
virtual void* do_allocate(size_t, size_t) {
__throw_bad_alloc();
}
virtual void do_deallocate(void *, size_t, size_t) {}
virtual bool do_is_equal(memory_resource const & __other) const noexcept
{ return &__other == this; }
};
namespace {
union ResourceInitHelper {
struct {
__new_delete_memory_resource_imp new_delete_res;
__null_memory_resource_imp null_res;
} resources;
char dummy;
_LIBCPP_CONSTEXPR_AFTER_CXX11 ResourceInitHelper() : resources() {}
~ResourceInitHelper() {}
};
// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
// attribute with a value that's reserved for the implementation (we're the implementation).
#include "memory_resource_init_helper.h"
} // end namespace
memory_resource * new_delete_resource() noexcept {
return &res_init.resources.new_delete_res;
}
memory_resource * null_memory_resource() noexcept {
return &res_init.resources.null_res;
}
// default_memory_resource()
static memory_resource *
__default_memory_resource(bool set = false, memory_resource * new_res = nullptr) noexcept
{
#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
static constinit atomic<memory_resource*> __res{&res_init.resources.new_delete_res};
if (set) {
new_res = new_res ? new_res : new_delete_resource();
// TODO: Can a weaker ordering be used?
return _VSTD::atomic_exchange_explicit(
&__res, new_res, memory_order_acq_rel);
}
else {
return _VSTD::atomic_load_explicit(
&__res, memory_order_acquire);
}
#elif !defined(_LIBCPP_HAS_NO_THREADS)
static constinit memory_resource *res = &res_init.resources.new_delete_res;
static mutex res_lock;
if (set) {
new_res = new_res ? new_res : new_delete_resource();
lock_guard<mutex> guard(res_lock);
memory_resource * old_res = res;
res = new_res;
return old_res;
} else {
lock_guard<mutex> guard(res_lock);
return res;
}
#else
static constinit memory_resource *res = &res_init.resources.new_delete_res;
if (set) {
new_res = new_res ? new_res : new_delete_resource();
memory_resource * old_res = res;
res = new_res;
return old_res;
} else {
return res;
}
#endif
}
memory_resource * get_default_resource() noexcept
{
return __default_memory_resource();
}
memory_resource * set_default_resource(memory_resource * __new_res) noexcept
{
return __default_memory_resource(true, __new_res);
}
_LIBCPP_END_NAMESPACE_LFTS_PMR
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