1 //===-- sanitizer_atomic_clang.h --------------------------------*- 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 // This file is a part of ThreadSanitizer/AddressSanitizer runtime. 10 // Not intended for direct inclusion. Include sanitizer_atomic.h. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef SANITIZER_ATOMIC_CLANG_H 15 #define SANITIZER_ATOMIC_CLANG_H 16 17 #if defined(__i386__) || defined(__x86_64__) 18 # include "sanitizer_atomic_clang_x86.h" 19 #else 20 # include "sanitizer_atomic_clang_other.h" 21 #endif 22 23 namespace __sanitizer { 24 25 // We would like to just use compiler builtin atomic operations 26 // for loads and stores, but they are mostly broken in clang: 27 // - they lead to vastly inefficient code generation 28 // (http://llvm.org/bugs/show_bug.cgi?id=17281) 29 // - 64-bit atomic operations are not implemented on x86_32 30 // (http://llvm.org/bugs/show_bug.cgi?id=15034) 31 // - they are not implemented on ARM 32 // error: undefined reference to '__atomic_load_4' 33 34 // See http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html 35 // for mappings of the memory model to different processors. 36 37 inline void atomic_signal_fence(memory_order) { 38 __asm__ __volatile__("" ::: "memory"); 39 } 40 41 inline void atomic_thread_fence(memory_order) { 42 __sync_synchronize(); 43 } 44 45 template<typename T> 46 inline typename T::Type atomic_fetch_add(volatile T *a, 47 typename T::Type v, memory_order mo) { 48 (void)mo; 49 DCHECK(!((uptr)a % sizeof(*a))); 50 return __sync_fetch_and_add(&a->val_dont_use, v); 51 } 52 53 template<typename T> 54 inline typename T::Type atomic_fetch_sub(volatile T *a, 55 typename T::Type v, memory_order mo) { 56 (void)mo; 57 DCHECK(!((uptr)a % sizeof(*a))); 58 return __sync_fetch_and_add(&a->val_dont_use, -v); 59 } 60 61 template<typename T> 62 inline typename T::Type atomic_exchange(volatile T *a, 63 typename T::Type v, memory_order mo) { 64 DCHECK(!((uptr)a % sizeof(*a))); 65 if (mo & (memory_order_release | memory_order_acq_rel | memory_order_seq_cst)) 66 __sync_synchronize(); 67 v = __sync_lock_test_and_set(&a->val_dont_use, v); 68 if (mo == memory_order_seq_cst) 69 __sync_synchronize(); 70 return v; 71 } 72 73 template <typename T> 74 inline bool atomic_compare_exchange_strong(volatile T *a, typename T::Type *cmp, 75 typename T::Type xchg, 76 memory_order mo) { 77 // Transitioned from __sync_val_compare_and_swap to support targets like 78 // SPARC V8 that cannot inline atomic cmpxchg. __atomic_compare_exchange 79 // can then be resolved from libatomic. __ATOMIC_SEQ_CST is used to best 80 // match the __sync builtin memory order. 81 return __atomic_compare_exchange(&a->val_dont_use, cmp, &xchg, false, 82 __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); 83 } 84 85 template<typename T> 86 inline bool atomic_compare_exchange_weak(volatile T *a, 87 typename T::Type *cmp, 88 typename T::Type xchg, 89 memory_order mo) { 90 return atomic_compare_exchange_strong(a, cmp, xchg, mo); 91 } 92 93 } // namespace __sanitizer 94 95 // This include provides explicit template instantiations for atomic_uint64_t 96 // on MIPS32, which does not directly support 8 byte atomics. It has to 97 // proceed the template definitions above. 98 #if defined(_MIPS_SIM) && defined(_ABIO32) 99 #include "sanitizer_atomic_clang_mips.h" 100 #endif 101 102 #undef ATOMIC_ORDER 103 104 #endif // SANITIZER_ATOMIC_CLANG_H 105