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|
//===------------------------ memory.cpp ----------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define _LIBCPP_BUILDING_MEMORY
#include "memory"
#ifndef _LIBCPP_HAS_NO_THREADS
#include "mutex"
#include "thread"
#endif
#include "include/atomic_support.h"
_LIBCPP_BEGIN_NAMESPACE_STD
namespace
{
// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
// should be sufficient for thread safety.
// See https://llvm.org/bugs/show_bug.cgi?id=22803
template <class T>
inline T
increment(T& t) _NOEXCEPT
{
return __libcpp_atomic_add(&t, 1, _AO_Relaxed);
}
template <class T>
inline T
decrement(T& t) _NOEXCEPT
{
return __libcpp_atomic_add(&t, -1, _AO_Acq_Rel);
}
} // namespace
const allocator_arg_t allocator_arg = allocator_arg_t();
bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {}
const char*
bad_weak_ptr::what() const _NOEXCEPT
{
return "bad_weak_ptr";
}
__shared_count::~__shared_count()
{
}
void
__shared_count::__add_shared() _NOEXCEPT
{
increment(__shared_owners_);
}
bool
__shared_count::__release_shared() _NOEXCEPT
{
if (decrement(__shared_owners_) == -1)
{
__on_zero_shared();
return true;
}
return false;
}
__shared_weak_count::~__shared_weak_count()
{
}
void
__shared_weak_count::__add_shared() _NOEXCEPT
{
__shared_count::__add_shared();
}
void
__shared_weak_count::__add_weak() _NOEXCEPT
{
increment(__shared_weak_owners_);
}
void
__shared_weak_count::__release_shared() _NOEXCEPT
{
if (__shared_count::__release_shared())
__release_weak();
}
void
__shared_weak_count::__release_weak() _NOEXCEPT
{
if (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 0;
}
#if !defined(_LIBCPP_NO_RTTI) || !defined(_LIBCPP_BUILD_STATIC)
const void*
__shared_weak_count::__get_deleter(const type_info&) const _NOEXCEPT
{
return 0;
}
#endif // _LIBCPP_NO_RTTI
#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
static const std::size_t __sp_mut_count = 16;
static pthread_mutex_t mut_back_imp[__sp_mut_count] =
{
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER
};
static mutex* mut_back = reinterpret_cast<std::mutex*>(mut_back_imp);
_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
: __lx(p)
{
}
void
__sp_mut::lock() _NOEXCEPT
{
mutex& m = *static_cast<mutex*>(__lx);
unsigned count = 0;
while (!m.try_lock())
{
if (++count > 16)
{
m.lock();
break;
}
this_thread::yield();
}
}
void
__sp_mut::unlock() _NOEXCEPT
{
static_cast<mutex*>(__lx)->unlock();
}
__sp_mut&
__get_sp_mut(const void* p)
{
static __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]
};
return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
}
#endif // defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
void
declare_reachable(void*)
{
}
void
declare_no_pointers(char*, size_t)
{
}
void
undeclare_no_pointers(char*, size_t)
{
}
pointer_safety
get_pointer_safety() _NOEXCEPT
{
return pointer_safety::relaxed;
}
void*
__undeclare_reachable(void* p)
{
return p;
}
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<size_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
|
