libsanitizer/sanitizer_common/sanitizer_atomic_clang.h

   1 //===-- sanitizer_atomic_clang.h --------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of ThreadSanitizer/AddressSanitizer runtime.
   9 // Not intended for direct inclusion. Include sanitizer_atomic.h.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef SANITIZER_ATOMIC_CLANG_H
  14 #define SANITIZER_ATOMIC_CLANG_H
  15
  16 #if defined(__i386__) || defined(__x86_64__)
  17 # include "sanitizer_atomic_clang_x86.h"
  18 #else
  19 # include "sanitizer_atomic_clang_other.h"
  20 #endif
  21
  22 namespace __sanitizer {
  23
  24 // We would like to just use compiler builtin atomic operations
  25 // for loads and stores, but they are mostly broken in clang:
  26 // - they lead to vastly inefficient code generation
  27 // (http://llvm.org/bugs/show_bug.cgi?id=17281)
  28 // - 64-bit atomic operations are not implemented on x86_32
  29 // (http://llvm.org/bugs/show_bug.cgi?id=15034)
  30 // - they are not implemented on ARM
  31 // error: undefined reference to '__atomic_load_4'
  32
  33 // See http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html
  34 // for mappings of the memory model to different processors.
  35
  36 INLINE void atomic_signal_fence(memory_order) {
  37   __asm__ __volatile__("" ::: "memory");
  38 }
  39
  40 INLINE void atomic_thread_fence(memory_order) {
  41   __sync_synchronize();
  42 }
  43
  44 template<typename T>
  45 INLINE typename T::Type atomic_fetch_add(volatile T *a,
  46     typename T::Type v, memory_order mo) {
  47   (void)mo;
  48   DCHECK(!((uptr)a % sizeof(*a)));
  49   return __sync_fetch_and_add(&a->val_dont_use, v);
  50 }
  51
  52 template<typename T>
  53 INLINE typename T::Type atomic_fetch_sub(volatile T *a,
  54     typename T::Type v, memory_order mo) {
  55   (void)mo;
  56   DCHECK(!((uptr)a % sizeof(*a)));
  57   return __sync_fetch_and_add(&a->val_dont_use, -v);
  58 }
  59
  60 template<typename T>
  61 INLINE typename T::Type atomic_exchange(volatile T *a,
  62     typename T::Type v, memory_order mo) {
  63   DCHECK(!((uptr)a % sizeof(*a)));
  64   if (mo & (memory_order_release | memory_order_acq_rel | memory_order_seq_cst))
  65     __sync_synchronize();
  66   v = __sync_lock_test_and_set(&a->val_dont_use, v);
  67   if (mo == memory_order_seq_cst)
  68     __sync_synchronize();
  69   return v;
  70 }
  71
  72 template<typename T>
  73 INLINE bool atomic_compare_exchange_strong(volatile T *a,
  74                                            typename T::Type *cmp,
  75                                            typename T::Type xchg,
  76                                            memory_order mo) {
  77   typedef typename T::Type Type;
  78   Type cmpv = *cmp;
  79   Type prev = __sync_val_compare_and_swap(&a->val_dont_use, cmpv, xchg);
  80   if (prev == cmpv)
  81     return true;
  82   *cmp = prev;
  83   return false;
  84 }
  85
  86 template<typename T>
  87 INLINE bool atomic_compare_exchange_weak(volatile T *a,
  88                                          typename T::Type *cmp,
  89                                          typename T::Type xchg,
  90                                          memory_order mo) {
  91   return atomic_compare_exchange_strong(a, cmp, xchg, mo);
  92 }
  93
  94 }  // namespace __sanitizer
  95
  96 #undef ATOMIC_ORDER
  97
  98 #endif  // SANITIZER_ATOMIC_CLANG_H