Home | History | Annotate | Line # | Download | only in sanitizer_common 
      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 platforms, which do not directly support 8 byte atomics. It has to
     97 // proceed the template definitions above.
     98 #if defined(_MIPS_SIM) && defined(_ABIO32) && _MIPS_SIM == _ABIO32
     99 #  include "sanitizer_atomic_clang_mips.h"
    100 #endif
    101 #if SANITIZER_NETBSD
    102 #  include <machine/types.h>
    103 #  ifndef __HAVE_ATOMIC64_OPS
    104 #    include "sanitizer_atomic_clang_mips.h"
    105 #  endif
    106 #endif
    107 
    108 #undef ATOMIC_ORDER
    109 
    110 #endif  // SANITIZER_ATOMIC_CLANG_H
    111