diff options
Diffstat (limited to 'libsanitizer/sanitizer_common/sanitizer_atomic_clang.h')
| -rw-r--r-- | libsanitizer/sanitizer_common/sanitizer_atomic_clang.h | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/libsanitizer/sanitizer_common/sanitizer_atomic_clang.h b/libsanitizer/sanitizer_common/sanitizer_atomic_clang.h index bb4611d51e6..88819e32a73 100644 --- a/libsanitizer/sanitizer_common/sanitizer_atomic_clang.h +++ b/libsanitizer/sanitizer_common/sanitizer_atomic_clang.h @@ -39,7 +39,17 @@ INLINE typename T::Type atomic_load( | memory_order_acquire | memory_order_seq_cst)); DCHECK(!((uptr)a % sizeof(*a))); typename T::Type v; - // FIXME(dvyukov): 64-bit load is not atomic on 32-bits. + // FIXME: + // 64-bit atomic operations are not atomic on 32-bit platforms. + // The implementation lacks necessary memory fences on ARM/PPC. + // We would like to use compiler builtin atomic operations, + // but they are mostly broken: + // - they lead to vastly inefficient code generation + // (http://llvm.org/bugs/show_bug.cgi?id=17281) + // - 64-bit atomic operations are not implemented on x86_32 + // (http://llvm.org/bugs/show_bug.cgi?id=15034) + // - they are not implemented on ARM + // error: undefined reference to '__atomic_load_4' if (mo == memory_order_relaxed) { v = a->val_dont_use; } else { @@ -55,7 +65,6 @@ INLINE void atomic_store(volatile T *a, typename T::Type v, memory_order mo) { DCHECK(mo & (memory_order_relaxed | memory_order_release | memory_order_seq_cst)); DCHECK(!((uptr)a % sizeof(*a))); - // FIXME(dvyukov): 64-bit store is not atomic on 32-bits. if (mo == memory_order_relaxed) { a->val_dont_use = v; } else { @@ -111,12 +120,14 @@ INLINE bool atomic_compare_exchange_strong(volatile T *a, template<typename T> INLINE bool atomic_compare_exchange_weak(volatile T *a, - typename T::Type *cmp, - typename T::Type xchg, - memory_order mo) { + typename T::Type *cmp, + typename T::Type xchg, + memory_order mo) { return atomic_compare_exchange_strong(a, cmp, xchg, mo); } } // namespace __sanitizer +#undef ATOMIC_ORDER + #endif // SANITIZER_ATOMIC_CLANG_H |