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| 1 | //===-- Shared/RefCnt.h - Helper to keep track of references --- C++ ------===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | //===----------------------------------------------------------------------===// |
| 10 | |
| 11 | #ifndef OMPTARGET_SHARED_REF_CNT_H |
| 12 | #define OMPTARGET_SHARED_REF_CNT_H |
| 13 | |
| 14 | #include <atomic> |
| 15 | #include <cassert> |
| 16 | #include <limits> |
| 17 | #include <memory> |
| 18 | |
| 19 | namespace llvm { |
| 20 | namespace omp { |
| 21 | namespace target { |
| 22 | |
| 23 | /// Utility class for thread-safe reference counting. Any class that needs |
| 24 | /// objects' reference counting can inherit from this entity or have it as a |
| 25 | /// class data member. |
| 26 | template <typename Ty = uint32_t, |
| 27 | std::memory_order MemoryOrder = std::memory_order_relaxed> |
| 28 | struct RefCountTy { |
| 29 | /// Create a refcount object initialized to zero. |
| 30 | RefCountTy() : Refs(0) {} |
| 31 | |
| 32 | ~RefCountTy() { assert(Refs == 0 && "Destroying with non-zero refcount"); } |
| 33 | |
| 34 | /// Increase the reference count atomically. |
| 35 | void increase() { Refs.fetch_add(1, MemoryOrder); } |
| 36 | |
| 37 | /// Decrease the reference count and return whether it became zero. Decreasing |
| 38 | /// the counter in more units than it was previously increased results in |
| 39 | /// undefined behavior. |
| 40 | bool decrease() { |
| 41 | Ty Prev = Refs.fetch_sub(1, MemoryOrder); |
| 42 | assert(Prev > 0 && "Invalid refcount"); |
| 43 | return (Prev == 1); |
| 44 | } |
| 45 | |
| 46 | Ty get() const { return Refs.load(MemoryOrder); } |
| 47 | |
| 48 | private: |
| 49 | /// The atomic reference counter. |
| 50 | std::atomic<Ty> Refs; |
| 51 | }; |
| 52 | } // namespace target |
| 53 | } // namespace omp |
| 54 | } // namespace llvm |
| 55 | |
| 56 | #endif |
| 57 |
Warning: This file is not a C or C++ file. It does not have highlighting.