Cleanup the semaphore headers

libcudacxx/include/cuda/std/__cuda/semaphore.h → libcudacxx/include/cuda/__semaphore/counting_semaphore.h

@@ -8,8 +8,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCUDACXX___CUDA_SEMAPHORE_H
-#define _LIBCUDACXX___CUDA_SEMAPHORE_H
+#ifndef _CUDA___SEMAPHORE_COUNTING_SEMAPHORE_H
+#define _CUDA___SEMAPHORE_COUNTING_SEMAPHORE_H
 
 #include <cuda/std/detail/__config>
 
@@ -21,16 +21,21 @@
 #  pragma system_header
 #endif // no system header
 
+#include <cuda/std/__semaphore/atomic_semaphore.h>
+#include <cuda/std/cstdint>
+
+_CCCL_PUSH_MACROS
+
 _LIBCUDACXX_BEGIN_NAMESPACE_CUDA
 
 template <thread_scope _Sco, ptrdiff_t __least_max_value = INT_MAX>
-class counting_semaphore : public _CUDA_VSTD::__semaphore_base<__least_max_value, _Sco>
+class counting_semaphore : public _CUDA_VSTD::__atomic_semaphore<_Sco, __least_max_value>
 {
-  static_assert(__least_max_value <= _CUDA_VSTD::__semaphore_base<__least_max_value, _Sco>::max(), "");
+  static_assert(__least_max_value <= _CUDA_VSTD::__atomic_semaphore<_Sco, __least_max_value>::max(), "");
 
 public:
   _LIBCUDACXX_HIDE_FROM_ABI constexpr counting_semaphore(ptrdiff_t __count = 0)
-      : _CUDA_VSTD::__semaphore_base<__least_max_value, _Sco>(__count)
+      : _CUDA_VSTD::__atomic_semaphore<_Sco, __least_max_value>(__count)
   {}
   _CCCL_HIDE_FROM_ABI ~counting_semaphore() = default;
 
@@ -43,4 +48,6 @@ using binary_semaphore = counting_semaphore<_Sco, 1>;
 
 _LIBCUDACXX_END_NAMESPACE_CUDA
 
-#endif // _LIBCUDACXX___CUDA_SEMAPHORE_H
+_CCCL_POP_MACROS
+
+#endif // _CUDA___SEMAPHORE_COUNTING_SEMAPHORE_H

libcudacxx/include/cuda/semaphore

@@ -11,6 +11,21 @@
 #ifndef _CUDA_SEMAPHORE
 #define _CUDA_SEMAPHORE
 
+#if defined(__CUDA_ARCH__) && __CUDA_ARCH__ < 700
+#  error "CUDA synchronization primitives are only supported for sm_70 and up."
+#endif
+
+#include <cuda/std/detail/__config>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+
+#include <cuda/__semaphore/counting_semaphore.h>
 #include <cuda/std/semaphore>
 
 #endif // _CUDA_SEMAPHORE

libcudacxx/include/cuda/std/__semaphore/atomic_semaphore.h

@@ -0,0 +1,234 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCUDACXX___SEMAPHORE_ATOMIC_SEMAPHORE_H
+#define _LIBCUDACXX___SEMAPHORE_ATOMIC_SEMAPHORE_H
+
+#include <cuda/std/detail/__config>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+
+#include <cuda/std/atomic>
+#include <cuda/std/chrono>
+#include <cuda/std/cstdint>
+
+_CCCL_PUSH_MACROS
+
+_LIBCUDACXX_BEGIN_NAMESPACE_STD
+
+template <thread_scope _Sco, ptrdiff_t __least_max_value>
+class __atomic_semaphore
+{
+  __atomic_impl<ptrdiff_t, _Sco> __count;
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool __fetch_sub_if_slow(ptrdiff_t __old)
+  {
+    while (__old != 0)
+    {
+      if (__count.compare_exchange_weak(__old, __old - 1, memory_order_acquire, memory_order_relaxed))
+      {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool __fetch_sub_if()
+  {
+    ptrdiff_t __old = __count.load(memory_order_acquire);
+    if (__old == 0)
+    {
+      return false;
+    }
+    if (__count.compare_exchange_weak(__old, __old - 1, memory_order_acquire, memory_order_relaxed))
+    {
+      return true;
+    }
+    return __fetch_sub_if_slow(__old); // fail only if not __available
+  }
+
+  _LIBCUDACXX_HIDE_FROM_ABI void __wait_slow()
+  {
+    while (1)
+    {
+      ptrdiff_t const __old = __count.load(memory_order_acquire);
+      if (__old != 0)
+      {
+        break;
+      }
+      __count.wait(__old, memory_order_relaxed);
+    }
+  }
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool __acquire_slow_timed(chrono::nanoseconds const& __rel_time)
+  {
+    return __libcpp_thread_poll_with_backoff(
+      [this]() {
+        ptrdiff_t const __old = __count.load(memory_order_acquire);
+        return __old != 0 && __fetch_sub_if_slow(__old);
+      },
+      __rel_time);
+  }
+
+public:
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI static constexpr ptrdiff_t max() noexcept
+  {
+    return numeric_limits<ptrdiff_t>::max();
+  }
+
+  _LIBCUDACXX_HIDE_FROM_ABI constexpr __atomic_semaphore(ptrdiff_t __count) noexcept
+      : __count(__count)
+  {}
+
+  _CCCL_HIDE_FROM_ABI ~__atomic_semaphore() = default;
+
+  __atomic_semaphore(__atomic_semaphore const&)            = delete;
+  __atomic_semaphore& operator=(__atomic_semaphore const&) = delete;
+
+  _LIBCUDACXX_HIDE_FROM_ABI void release(ptrdiff_t __update = 1)
+  {
+    __count.fetch_add(__update, memory_order_release);
+    if (__update > 1)
+    {
+      __count.notify_all();
+    }
+    else
+    {
+      __count.notify_one();
+    }
+  }
+
+  _LIBCUDACXX_HIDE_FROM_ABI void acquire()
+  {
+    while (!try_acquire())
+    {
+      __wait_slow();
+    }
+  }
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire() noexcept
+  {
+    return __fetch_sub_if();
+  }
+
+  template <class Clock, class Duration>
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire_until(chrono::time_point<Clock, Duration> const& __abs_time)
+  {
+    if (try_acquire())
+    {
+      return true;
+    }
+    else
+    {
+      return __acquire_slow_timed(__abs_time - Clock::now());
+    }
+  }
+
+  template <class Rep, class Period>
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire_for(chrono::duration<Rep, Period> const& __rel_time)
+  {
+    if (try_acquire())
+    {
+      return true;
+    }
+    else
+    {
+      return __acquire_slow_timed(__rel_time);
+    }
+  }
+};
+
+template <thread_scope _Sco>
+class __atomic_semaphore<_Sco, 1>
+{
+  __atomic_impl<int, _Sco> __available;
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool __acquire_slow_timed(chrono::nanoseconds const& __rel_time)
+  {
+    return __libcpp_thread_poll_with_backoff(
+      [this]() {
+        return try_acquire();
+      },
+      __rel_time);
+  }
+
+public:
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI static constexpr ptrdiff_t max() noexcept
+  {
+    return 1;
+  }
+
+  _LIBCUDACXX_HIDE_FROM_ABI constexpr __atomic_semaphore(ptrdiff_t __available)
+      : __available(__available)
+  {}
+
+  _CCCL_HIDE_FROM_ABI ~__atomic_semaphore() = default;
+
+  __atomic_semaphore(__atomic_semaphore const&)            = delete;
+  __atomic_semaphore& operator=(__atomic_semaphore const&) = delete;
+
+  _LIBCUDACXX_HIDE_FROM_ABI void release(ptrdiff_t __update = 1)
+  {
+    _CCCL_ASSERT(__update == 1, "");
+    __available.store(1, memory_order_release);
+    __available.notify_one();
+    (void) __update;
+  }
+
+  _LIBCUDACXX_HIDE_FROM_ABI void acquire()
+  {
+    while (!try_acquire())
+    {
+      __available.wait(0, memory_order_relaxed);
+    }
+  }
+
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire() noexcept
+  {
+    return 1 == __available.exchange(0, memory_order_acquire);
+  }
+
+  template <class Clock, class Duration>
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire_until(chrono::time_point<Clock, Duration> const& __abs_time)
+  {
+    if (try_acquire())
+    {
+      return true;
+    }
+    else
+    {
+      return __acquire_slow_timed(__abs_time - Clock::now());
+    }
+  }
+
+  template <class Rep, class Period>
+  _CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI bool try_acquire_for(chrono::duration<Rep, Period> const& __rel_time)
+  {
+    if (try_acquire())
+    {
+      return true;
+    }
+    else
+    {
+      return __acquire_slow_timed(__rel_time);
+    }
+  }
+};
+
+_LIBCUDACXX_END_NAMESPACE_STD
+
+_CCCL_POP_MACROS
+
+#endif // _LIBCUDACXX___SEMAPHORE_ATOMIC_SEMAPHORE_H

libcudacxx/include/cuda/std/__semaphore/counting_semaphore.h

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCUDACXX___SEMAPHORE_COUNTING_SEMAPHORE_H
+#define _LIBCUDACXX___SEMAPHORE_COUNTING_SEMAPHORE_H
+
+#include <cuda/std/detail/__config>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+
+#include <cuda/std/__semaphore/atomic_semaphore.h>
+#include <cuda/std/cstdint>
+
+_CCCL_PUSH_MACROS
+
+_LIBCUDACXX_BEGIN_NAMESPACE_STD
+
+template <ptrdiff_t __least_max_value = INT_MAX>
+class counting_semaphore : public __atomic_semaphore<thread_scope_system, __least_max_value>
+{
+  static_assert(__least_max_value <= __atomic_semaphore<thread_scope_system, __least_max_value>::max(), "");
+
+public:
+  _LIBCUDACXX_HIDE_FROM_ABI constexpr counting_semaphore(ptrdiff_t __count = 0)
+      : __atomic_semaphore<thread_scope_system, __least_max_value>(__count)
+  {}
+  _CCCL_HIDE_FROM_ABI ~counting_semaphore() = default;
+
+  counting_semaphore(const counting_semaphore&)            = delete;
+  counting_semaphore& operator=(const counting_semaphore&) = delete;
+};
+
+using binary_semaphore = counting_semaphore<1>;
+
+_LIBCUDACXX_END_NAMESPACE_STD
+
+_CCCL_POP_MACROS
+
+#endif // _LIBCUDACXX___SEMAPHORE_COUNTING_SEMAPHORE_H