xref: /freebsd/contrib/llvm-project/libcxx/include/barrier (revision 7a6dacaca14b62ca4b74406814becb87a3fefac0)
15ffd83dbSDimitry Andric// -*- C++ -*-
2349cc55cSDimitry Andric//===----------------------------------------------------------------------===//
35ffd83dbSDimitry Andric//
45ffd83dbSDimitry Andric// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
55ffd83dbSDimitry Andric// See https://llvm.org/LICENSE.txt for license information.
65ffd83dbSDimitry Andric// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
75ffd83dbSDimitry Andric//
85ffd83dbSDimitry Andric//===----------------------------------------------------------------------===//
95ffd83dbSDimitry Andric
105ffd83dbSDimitry Andric#ifndef _LIBCPP_BARRIER
115ffd83dbSDimitry Andric#define _LIBCPP_BARRIER
125ffd83dbSDimitry Andric
135ffd83dbSDimitry Andric/*
145ffd83dbSDimitry Andric    barrier synopsis
155ffd83dbSDimitry Andric
165ffd83dbSDimitry Andricnamespace std
175ffd83dbSDimitry Andric{
185ffd83dbSDimitry Andric
195ffd83dbSDimitry Andric  template<class CompletionFunction = see below>
205ffd83dbSDimitry Andric  class barrier
215ffd83dbSDimitry Andric  {
225ffd83dbSDimitry Andric  public:
235ffd83dbSDimitry Andric    using arrival_token = see below;
245ffd83dbSDimitry Andric
25e8d8bef9SDimitry Andric    static constexpr ptrdiff_t max() noexcept;
26e8d8bef9SDimitry Andric
275ffd83dbSDimitry Andric    constexpr explicit barrier(ptrdiff_t phase_count,
285ffd83dbSDimitry Andric                               CompletionFunction f = CompletionFunction());
295ffd83dbSDimitry Andric    ~barrier();
305ffd83dbSDimitry Andric
315ffd83dbSDimitry Andric    barrier(const barrier&) = delete;
325ffd83dbSDimitry Andric    barrier& operator=(const barrier&) = delete;
335ffd83dbSDimitry Andric
345ffd83dbSDimitry Andric    [[nodiscard]] arrival_token arrive(ptrdiff_t update = 1);
355ffd83dbSDimitry Andric    void wait(arrival_token&& arrival) const;
365ffd83dbSDimitry Andric
375ffd83dbSDimitry Andric    void arrive_and_wait();
385ffd83dbSDimitry Andric    void arrive_and_drop();
395ffd83dbSDimitry Andric
405ffd83dbSDimitry Andric  private:
415ffd83dbSDimitry Andric    CompletionFunction completion; // exposition only
425ffd83dbSDimitry Andric  };
435ffd83dbSDimitry Andric
445ffd83dbSDimitry Andric}
455ffd83dbSDimitry Andric
465ffd83dbSDimitry Andric*/
475ffd83dbSDimitry Andric
48*7a6dacacSDimitry Andric#include <__config>
49*7a6dacacSDimitry Andric
50*7a6dacacSDimitry Andric#ifdef _LIBCPP_HAS_NO_THREADS
51*7a6dacacSDimitry Andric#  error "<barrier> is not supported since libc++ has been configured without support for threads."
52*7a6dacacSDimitry Andric#endif
53*7a6dacacSDimitry Andric
5481ad6265SDimitry Andric#include <__assert> // all public C++ headers provide the assertion handler
5506c3fb27SDimitry Andric#include <__atomic/atomic_base.h>
5606c3fb27SDimitry Andric#include <__atomic/memory_order.h>
57e8d8bef9SDimitry Andric#include <__availability>
58bdd1243dSDimitry Andric#include <__memory/unique_ptr.h>
5906c3fb27SDimitry Andric#include <__thread/poll_with_backoff.h>
6004eeddc0SDimitry Andric#include <__thread/timed_backoff_policy.h>
61bdd1243dSDimitry Andric#include <__utility/move.h>
6206c3fb27SDimitry Andric#include <cstddef>
6306c3fb27SDimitry Andric#include <cstdint>
6481ad6265SDimitry Andric#include <limits>
6506c3fb27SDimitry Andric#include <version>
665ffd83dbSDimitry Andric
675ffd83dbSDimitry Andric#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
685ffd83dbSDimitry Andric#  pragma GCC system_header
695ffd83dbSDimitry Andric#endif
705ffd83dbSDimitry Andric
71e8d8bef9SDimitry Andric_LIBCPP_PUSH_MACROS
72e8d8bef9SDimitry Andric#include <__undef_macros>
73e8d8bef9SDimitry Andric
745ffd83dbSDimitry Andric#if _LIBCPP_STD_VER >= 14
755ffd83dbSDimitry Andric
765ffd83dbSDimitry Andric_LIBCPP_BEGIN_NAMESPACE_STD
775ffd83dbSDimitry Andric
78cb14a3feSDimitry Andricstruct __empty_completion {
79cb14a3feSDimitry Andric  inline _LIBCPP_HIDE_FROM_ABI void operator()() noexcept {}
805ffd83dbSDimitry Andric};
815ffd83dbSDimitry Andric
825ffd83dbSDimitry Andric#  ifndef _LIBCPP_HAS_NO_TREE_BARRIER
835ffd83dbSDimitry Andric
845ffd83dbSDimitry Andric/*
855ffd83dbSDimitry Andric
865ffd83dbSDimitry AndricThe default implementation of __barrier_base is a classic tree barrier.
875ffd83dbSDimitry Andric
885ffd83dbSDimitry AndricIt looks different from literature pseudocode for two main reasons:
895ffd83dbSDimitry Andric 1. Threads that call into std::barrier functions do not provide indices,
905ffd83dbSDimitry Andric    so a numbering step is added before the actual barrier algorithm,
915ffd83dbSDimitry Andric    appearing as an N+1 round to the N rounds of the tree barrier.
925ffd83dbSDimitry Andric 2. A great deal of attention has been paid to avoid cache line thrashing
935ffd83dbSDimitry Andric    by flattening the tree structure into cache-line sized arrays, that
945ffd83dbSDimitry Andric    are indexed in an efficient way.
955ffd83dbSDimitry Andric
965ffd83dbSDimitry Andric*/
975ffd83dbSDimitry Andric
985ffd83dbSDimitry Andricusing __barrier_phase_t = uint8_t;
995ffd83dbSDimitry Andric
1005ffd83dbSDimitry Andricclass __barrier_algorithm_base;
1015ffd83dbSDimitry Andric
102cb14a3feSDimitry Andric_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __barrier_algorithm_base*
103cb14a3feSDimitry Andric__construct_barrier_algorithm_base(ptrdiff_t& __expected);
1045ffd83dbSDimitry Andric
105cb14a3feSDimitry Andric_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI bool
106cb14a3feSDimitry Andric__arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier, __barrier_phase_t __old_phase);
1075ffd83dbSDimitry Andric
108cb14a3feSDimitry Andric_LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void
109cb14a3feSDimitry Andric__destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier);
1105ffd83dbSDimitry Andric
1115ffd83dbSDimitry Andrictemplate <class _CompletionF>
1125ffd83dbSDimitry Andricclass __barrier_base {
11381ad6265SDimitry Andric  ptrdiff_t __expected_;
114cb14a3feSDimitry Andric  unique_ptr<__barrier_algorithm_base, void (*)(__barrier_algorithm_base*)> __base_;
11581ad6265SDimitry Andric  __atomic_base<ptrdiff_t> __expected_adjustment_;
11681ad6265SDimitry Andric  _CompletionF __completion_;
11781ad6265SDimitry Andric  __atomic_base<__barrier_phase_t> __phase_;
1185ffd83dbSDimitry Andric
1195ffd83dbSDimitry Andricpublic:
1205ffd83dbSDimitry Andric  using arrival_token = __barrier_phase_t;
1215ffd83dbSDimitry Andric
122cb14a3feSDimitry Andric  static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { return numeric_limits<ptrdiff_t>::max(); }
1235ffd83dbSDimitry Andric
1245f757f3fSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI
1255ffd83dbSDimitry Andric  __barrier_base(ptrdiff_t __expected, _CompletionF __completion = _CompletionF())
126cb14a3feSDimitry Andric      : __expected_(__expected),
127cb14a3feSDimitry Andric        __base_(std::__construct_barrier_algorithm_base(this->__expected_), &__destroy_barrier_algorithm_base),
128cb14a3feSDimitry Andric        __expected_adjustment_(0),
129cb14a3feSDimitry Andric        __completion_(std::move(__completion)),
130cb14a3feSDimitry Andric        __phase_(0) {}
131cb14a3feSDimitry Andric  [[__nodiscard__]] _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t __update) {
132*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
13306c3fb27SDimitry Andric        __update <= __expected_, "update is greater than the expected count for the current barrier phase");
13406c3fb27SDimitry Andric
13581ad6265SDimitry Andric    auto const __old_phase = __phase_.load(memory_order_relaxed);
136753f127fSDimitry Andric    for (; __update; --__update)
13781ad6265SDimitry Andric      if (__arrive_barrier_algorithm_base(__base_.get(), __old_phase)) {
13881ad6265SDimitry Andric        __completion_();
13981ad6265SDimitry Andric        __expected_ += __expected_adjustment_.load(memory_order_relaxed);
14081ad6265SDimitry Andric        __expected_adjustment_.store(0, memory_order_relaxed);
14181ad6265SDimitry Andric        __phase_.store(__old_phase + 2, memory_order_release);
14281ad6265SDimitry Andric        __phase_.notify_all();
1435ffd83dbSDimitry Andric      }
1445ffd83dbSDimitry Andric    return __old_phase;
1455ffd83dbSDimitry Andric  }
146cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __old_phase) const {
147cb14a3feSDimitry Andric    auto const __test_fn = [this, __old_phase]() -> bool { return __phase_.load(memory_order_acquire) != __old_phase; };
148bdd1243dSDimitry Andric    std::__libcpp_thread_poll_with_backoff(__test_fn, __libcpp_timed_backoff_policy());
1495ffd83dbSDimitry Andric  }
150cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() {
15181ad6265SDimitry Andric    __expected_adjustment_.fetch_sub(1, memory_order_relaxed);
1525ffd83dbSDimitry Andric    (void)arrive(1);
1535ffd83dbSDimitry Andric  }
1545ffd83dbSDimitry Andric};
1555ffd83dbSDimitry Andric
1565ffd83dbSDimitry Andric#  else
1575ffd83dbSDimitry Andric
1585ffd83dbSDimitry Andric/*
1595ffd83dbSDimitry Andric
1605ffd83dbSDimitry AndricThe alternative implementation of __barrier_base is a central barrier.
1615ffd83dbSDimitry Andric
1625ffd83dbSDimitry AndricTwo versions of this algorithm are provided:
1635ffd83dbSDimitry Andric 1. A fairly straightforward implementation of the litterature for the
1645ffd83dbSDimitry Andric    general case where the completion function is not empty.
1655ffd83dbSDimitry Andric 2. An optimized implementation that exploits 2's complement arithmetic
1665ffd83dbSDimitry Andric    and well-defined overflow in atomic arithmetic, to handle the phase
1675ffd83dbSDimitry Andric    roll-over for free.
1685ffd83dbSDimitry Andric
1695ffd83dbSDimitry Andric*/
1705ffd83dbSDimitry Andric
1715ffd83dbSDimitry Andrictemplate <class _CompletionF>
1725ffd83dbSDimitry Andricclass __barrier_base {
1735ffd83dbSDimitry Andric  __atomic_base<ptrdiff_t> __expected;
1745ffd83dbSDimitry Andric  __atomic_base<ptrdiff_t> __arrived;
1755ffd83dbSDimitry Andric  _CompletionF __completion;
1765ffd83dbSDimitry Andric  __atomic_base<bool> __phase;
177cb14a3feSDimitry Andric
1785ffd83dbSDimitry Andricpublic:
1795ffd83dbSDimitry Andric  using arrival_token = bool;
1805ffd83dbSDimitry Andric
181cb14a3feSDimitry Andric  static constexpr ptrdiff_t max() noexcept { return numeric_limits<ptrdiff_t>::max(); }
1825ffd83dbSDimitry Andric
183cb14a3feSDimitry Andric  _LIBCPP_HIDE_FROM_ABI __barrier_base(ptrdiff_t __expected, _CompletionF __completion = _CompletionF())
184cb14a3feSDimitry Andric      : __expected(__expected), __arrived(__expected), __completion(std::move(__completion)), __phase(false) {}
185cb14a3feSDimitry Andric  [[nodiscard]] _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t update) {
1865ffd83dbSDimitry Andric    auto const __old_phase  = __phase.load(memory_order_relaxed);
1875ffd83dbSDimitry Andric    auto const __result     = __arrived.fetch_sub(update, memory_order_acq_rel) - update;
1885ffd83dbSDimitry Andric    auto const new_expected = __expected.load(memory_order_relaxed);
18906c3fb27SDimitry Andric
190*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
19106c3fb27SDimitry Andric        update <= new_expected, "update is greater than the expected count for the current barrier phase");
19206c3fb27SDimitry Andric
1935ffd83dbSDimitry Andric    if (0 == __result) {
1945ffd83dbSDimitry Andric      __completion();
1955ffd83dbSDimitry Andric      __arrived.store(new_expected, memory_order_relaxed);
1965ffd83dbSDimitry Andric      __phase.store(!__old_phase, memory_order_release);
1975ffd83dbSDimitry Andric      __phase.notify_all();
1985ffd83dbSDimitry Andric    }
1995ffd83dbSDimitry Andric    return __old_phase;
2005ffd83dbSDimitry Andric  }
201cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __old_phase) const {
2025ffd83dbSDimitry Andric    __phase.wait(__old_phase, memory_order_acquire);
2035ffd83dbSDimitry Andric  }
204cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() {
2055ffd83dbSDimitry Andric    __expected.fetch_sub(1, memory_order_relaxed);
2065ffd83dbSDimitry Andric    (void)arrive(1);
2075ffd83dbSDimitry Andric  }
2085ffd83dbSDimitry Andric};
2095ffd83dbSDimitry Andric
2105ffd83dbSDimitry Andrictemplate <>
2115ffd83dbSDimitry Andricclass __barrier_base<__empty_completion> {
2125ffd83dbSDimitry Andric  static constexpr uint64_t __expected_unit = 1ull;
2135ffd83dbSDimitry Andric  static constexpr uint64_t __arrived_unit  = 1ull << 32;
2145ffd83dbSDimitry Andric  static constexpr uint64_t __expected_mask = __arrived_unit - 1;
2155ffd83dbSDimitry Andric  static constexpr uint64_t __phase_bit     = 1ull << 63;
2165ffd83dbSDimitry Andric  static constexpr uint64_t __arrived_mask  = (__phase_bit - 1) & ~__expected_mask;
2175ffd83dbSDimitry Andric
2185ffd83dbSDimitry Andric  __atomic_base<uint64_t> __phase_arrived_expected;
2195ffd83dbSDimitry Andric
220cb14a3feSDimitry Andric  static _LIBCPP_HIDE_FROM_ABI constexpr uint64_t __init(ptrdiff_t __count) _NOEXCEPT {
221cb14a3feSDimitry Andric    return ((uint64_t(1u << 31) - __count) << 32) | (uint64_t(1u << 31) - __count);
2225ffd83dbSDimitry Andric  }
2235ffd83dbSDimitry Andric
2245ffd83dbSDimitry Andricpublic:
2255ffd83dbSDimitry Andric  using arrival_token = uint64_t;
2265ffd83dbSDimitry Andric
227cb14a3feSDimitry Andric  static constexpr ptrdiff_t max() noexcept { return ptrdiff_t(1u << 31) - 1; }
2285ffd83dbSDimitry Andric
229cb14a3feSDimitry Andric  _LIBCPP_HIDE_FROM_ABI explicit inline __barrier_base(ptrdiff_t __count, __empty_completion = __empty_completion())
230cb14a3feSDimitry Andric      : __phase_arrived_expected(__init(__count)) {}
231cb14a3feSDimitry Andric  [[nodiscard]] inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t update) {
2325ffd83dbSDimitry Andric    auto const __inc = __arrived_unit * update;
2335ffd83dbSDimitry Andric    auto const __old = __phase_arrived_expected.fetch_add(__inc, memory_order_acq_rel);
23406c3fb27SDimitry Andric
235*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
23606c3fb27SDimitry Andric        update <= __old, "update is greater than the expected count for the current barrier phase");
23706c3fb27SDimitry Andric
2385ffd83dbSDimitry Andric    if ((__old ^ (__old + __inc)) & __phase_bit) {
2395ffd83dbSDimitry Andric      __phase_arrived_expected.fetch_add((__old & __expected_mask) << 32, memory_order_relaxed);
2405ffd83dbSDimitry Andric      __phase_arrived_expected.notify_all();
2415ffd83dbSDimitry Andric    }
2425ffd83dbSDimitry Andric    return __old & __phase_bit;
2435ffd83dbSDimitry Andric  }
244cb14a3feSDimitry Andric  inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __phase) const {
2455ffd83dbSDimitry Andric    auto const __test_fn = [=]() -> bool {
2465ffd83dbSDimitry Andric      uint64_t const __current = __phase_arrived_expected.load(memory_order_acquire);
2475ffd83dbSDimitry Andric      return ((__current & __phase_bit) != __phase);
2485ffd83dbSDimitry Andric    };
2495ffd83dbSDimitry Andric    __libcpp_thread_poll_with_backoff(__test_fn, __libcpp_timed_backoff_policy());
2505ffd83dbSDimitry Andric  }
251cb14a3feSDimitry Andric  inline _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() {
2525ffd83dbSDimitry Andric    __phase_arrived_expected.fetch_add(__expected_unit, memory_order_relaxed);
2535ffd83dbSDimitry Andric    (void)arrive(1);
2545ffd83dbSDimitry Andric  }
2555ffd83dbSDimitry Andric};
2565ffd83dbSDimitry Andric
25781ad6265SDimitry Andric#  endif // !_LIBCPP_HAS_NO_TREE_BARRIER
2585ffd83dbSDimitry Andric
2595ffd83dbSDimitry Andrictemplate <class _CompletionF = __empty_completion>
2605ffd83dbSDimitry Andricclass barrier {
261bdd1243dSDimitry Andric  __barrier_base<_CompletionF> __b_;
262cb14a3feSDimitry Andric
2635ffd83dbSDimitry Andricpublic:
2645ffd83dbSDimitry Andric  using arrival_token = typename __barrier_base<_CompletionF>::arrival_token;
2655ffd83dbSDimitry Andric
266cb14a3feSDimitry Andric  static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { return __barrier_base<_CompletionF>::max(); }
2675ffd83dbSDimitry Andric
268cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI explicit barrier(
269cb14a3feSDimitry Andric      ptrdiff_t __count, _CompletionF __completion = _CompletionF())
2705f757f3fSDimitry Andric      : __b_(__count, std::move(__completion)) {
271*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
27206c3fb27SDimitry Andric        __count >= 0,
27306c3fb27SDimitry Andric        "barrier::barrier(ptrdiff_t, CompletionFunction): barrier cannot be initialized with a negative value");
274*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
27506c3fb27SDimitry Andric        __count <= max(),
27606c3fb27SDimitry Andric        "barrier::barrier(ptrdiff_t, CompletionFunction): barrier cannot be initialized with "
27706c3fb27SDimitry Andric        "a value greater than max()");
2785ffd83dbSDimitry Andric  }
2795ffd83dbSDimitry Andric
2805ffd83dbSDimitry Andric  barrier(barrier const&)            = delete;
2815ffd83dbSDimitry Andric  barrier& operator=(barrier const&) = delete;
2825ffd83dbSDimitry Andric
283cb14a3feSDimitry Andric  [[__nodiscard__]] _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI arrival_token arrive(ptrdiff_t __update = 1) {
284*7a6dacacSDimitry Andric    _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(__update > 0, "barrier:arrive must be called with a value greater than 0");
285bdd1243dSDimitry Andric    return __b_.arrive(__update);
2865ffd83dbSDimitry Andric  }
287cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void wait(arrival_token&& __phase) const {
2885f757f3fSDimitry Andric    __b_.wait(std::move(__phase));
2895ffd83dbSDimitry Andric  }
290cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_wait() { wait(arrive()); }
291cb14a3feSDimitry Andric  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void arrive_and_drop() { __b_.arrive_and_drop(); }
2925ffd83dbSDimitry Andric};
2935ffd83dbSDimitry Andric
2945ffd83dbSDimitry Andric_LIBCPP_END_NAMESPACE_STD
2955ffd83dbSDimitry Andric
2965ffd83dbSDimitry Andric#endif // _LIBCPP_STD_VER >= 14
2975ffd83dbSDimitry Andric
298e8d8bef9SDimitry Andric_LIBCPP_POP_MACROS
299e8d8bef9SDimitry Andric
300bdd1243dSDimitry Andric#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
30106c3fb27SDimitry Andric#  include <atomic>
302bdd1243dSDimitry Andric#  include <concepts>
303bdd1243dSDimitry Andric#  include <iterator>
304bdd1243dSDimitry Andric#  include <memory>
305bdd1243dSDimitry Andric#  include <stdexcept>
306bdd1243dSDimitry Andric#  include <variant>
307bdd1243dSDimitry Andric#endif
308bdd1243dSDimitry Andric
3095ffd83dbSDimitry Andric#endif //_LIBCPP_BARRIER
310