Louis Dionne e39095a32e [libc++] Define _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER whenever we enable warnings in the test suite
This should make CI consistent on all the compilers we support. Most of
this patch is working around various warnings emitted by GCC in our code
base, which are now being shown when we compile the tests.

After this patch, the whole test suite should be warning free on all
compilers we support and test, except for a few warnings on GCC that
we silence explicitly until we figure out the proper fix for them.

Differential Revision: https://reviews.llvm.org/D120684
2022-03-15 17:17:54 -04:00

113 lines
2.5 KiB
C++

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_LATCH
#define _LIBCPP_LATCH
/*
latch synopsis
namespace std
{
class latch
{
public:
static constexpr ptrdiff_t max() noexcept;
constexpr explicit latch(ptrdiff_t __expected);
~latch();
latch(const latch&) = delete;
latch& operator=(const latch&) = delete;
void count_down(ptrdiff_t __update = 1);
bool try_wait() const noexcept;
void wait() const;
void arrive_and_wait(ptrdiff_t __update = 1);
private:
ptrdiff_t __counter; // exposition only
};
}
*/
#include <__availability>
#include <__config>
#include <atomic>
#include <version>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#ifdef _LIBCPP_HAS_NO_THREADS
# error <latch> is not supported on this single threaded system
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
#if _LIBCPP_STD_VER >= 14
_LIBCPP_BEGIN_NAMESPACE_STD
class latch
{
__atomic_base<ptrdiff_t> __a;
public:
static constexpr ptrdiff_t max() noexcept {
return numeric_limits<ptrdiff_t>::max();
}
inline _LIBCPP_INLINE_VISIBILITY
constexpr explicit latch(ptrdiff_t __expected) : __a(__expected) { }
~latch() = default;
latch(const latch&) = delete;
latch& operator=(const latch&) = delete;
inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
void count_down(ptrdiff_t __update = 1)
{
auto const __old = __a.fetch_sub(__update, memory_order_release);
if(__old == __update)
__a.notify_all();
}
inline _LIBCPP_INLINE_VISIBILITY
bool try_wait() const noexcept
{
return 0 == __a.load(memory_order_acquire);
}
inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
void wait() const
{
__cxx_atomic_wait(&__a.__a_, [&]() -> bool {
return try_wait();
});
}
inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
void arrive_and_wait(ptrdiff_t __update = 1)
{
count_down(__update);
wait();
}
};
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER >= 14
_LIBCPP_POP_MACROS
#endif //_LIBCPP_LATCH