//===----------------------------------------------------------------------===//

//

// 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 <__config>

#ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS

#  define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS

#endif

#include <memory>

#ifndef _LIBCPP_HAS_NO_THREADS

#  include <mutex>

#  include <thread>

#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)

#    pragma comment(lib, "pthread")

#  endif

#endif

#include "include/atomic_support.h"

_LIBCPP_BEGIN_NAMESPACE_STD

bad_weak_ptr::~bad_weak_ptr() noexcept {}

const char* bad_weak_ptr::what() const noexcept { return "bad_weak_ptr"; }

__shared_count::~__shared_count() {}

__shared_weak_count::~__shared_weak_count() {}

#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)

void __shared_count::__add_shared() noexcept { __libcpp_atomic_refcount_increment(__shared_owners_); }

bool __shared_count::__release_shared() noexcept {

  if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {

    __on_zero_shared();

    return true;

  }

  return false;

}

void __shared_weak_count::__add_shared() noexcept { __shared_count::__add_shared(); }

void __shared_weak_count::__add_weak() noexcept { __libcpp_atomic_refcount_increment(__shared_weak_owners_); }

void __shared_weak_count::__release_shared() noexcept {

  if (__shared_count::__release_shared())

    __release_weak();

}

#endif // _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS

void __shared_weak_count::__release_weak() noexcept {

  // NOTE: The acquire load here is an optimization of the very

  // common case where a shared pointer is being destructed while

  // having no other contended references.

  //

  // BENEFIT: We avoid expensive atomic stores like XADD and STREX

  // in a common case.  Those instructions are slow and do nasty

  // things to caches.

  //

  // IS THIS SAFE?  Yes.  During weak destruction, if we see that we

  // are the last reference, we know that no-one else is accessing

  // us. If someone were accessing us, then they would be doing so

  // while the last shared / weak_ptr was being destructed, and

  // that's undefined anyway.

  //

  // If we see anything other than a 0, then we have possible

  // contention, and need to use an atomicrmw primitive.

  // The same arguments don't apply for increment, where it is legal

  // (though inadvisable) to share shared_ptr references between

  // threads, and have them all get copied at once.  The argument

  // also doesn't apply for __release_shared, because an outstanding

  // weak_ptr::lock() could read / modify the shared count.

  if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0) {

    // no need to do this store, because we are about

    // to destroy everything.

    //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);

    __on_zero_shared_weak();

  } else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)

    __on_zero_shared_weak();

}

__shared_weak_count* __shared_weak_count::lock() noexcept {

  long object_owners = __libcpp_atomic_load(&__shared_owners_);

  while (object_owners != -1) {

    if (__libcpp_atomic_compare_exchange(&__shared_owners_, &object_owners, object_owners + 1))

      return this;

  }

  return nullptr;

}

const void* __shared_weak_count::__get_deleter(const type_info&) const noexcept { return nullptr; }

#if !defined(_LIBCPP_HAS_NO_THREADS)

static constexpr std::size_t __sp_mut_count                = 32;

static constinit __libcpp_mutex_t mut_back[__sp_mut_count] = {

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,

    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER};

constexpr __sp_mut::__sp_mut(void* p) noexcept : __lx_(p) {}

void __sp_mut::lock() noexcept {

  auto m = static_cast<__libcpp_mutex_t*>(__lx_);

  __libcpp_mutex_lock(m);

}

void __sp_mut::unlock() noexcept { __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx_)); }

__sp_mut& __get_sp_mut(const void* p) {

  static constinit __sp_mut muts[__sp_mut_count] = {

      &mut_back[0],  &mut_back[1],  &mut_back[2],  &mut_back[3],  &mut_back[4],  &mut_back[5],  &mut_back[6],

      &mut_back[7],  &mut_back[8],  &mut_back[9],  &mut_back[10], &mut_back[11], &mut_back[12], &mut_back[13],

      &mut_back[14], &mut_back[15], &mut_back[16], &mut_back[17], &mut_back[18], &mut_back[19], &mut_back[20],

      &mut_back[21], &mut_back[22], &mut_back[23], &mut_back[24], &mut_back[25], &mut_back[26], &mut_back[27],

      &mut_back[28], &mut_back[29], &mut_back[30], &mut_back[31]};

  return muts[hash<const void*>()(p) & (__sp_mut_count - 1)];

}

#endif // !defined(_LIBCPP_HAS_NO_THREADS)

void* align(size_t alignment, size_t size, void*& ptr, size_t& space) {

  void* r = nullptr;

  if (size <= space) {

    char* p1 = static_cast<char*>(ptr);

    char* p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 + (alignment - 1)) & -alignment);

    size_t d = static_cast<size_t>(p2 - p1);

    if (d <= space - size) {

      r   = p2;

      ptr = r;

      space -= d;

    }

  }

  return r;

}

_LIBCPP_END_NAMESPACE_STD