[compiler-rt] r177854 - [Sanitizer] First effort to implement atomic_compare_exchange for 1-byte vars on Windows

[Alexey Samsonov]

Author: samsonov
Date: Mon Mar 25 04:23:30 2013
New Revision: 177854

URL: http://llvm.org/viewvc/llvm-project?rev=177854&view=rev
Log:
[Sanitizer] First effort to implement atomic_compare_exchange for 1-byte vars on Windows

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_atomic_msvc.h

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_atomic_msvc.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_atomic_msvc.h?rev=177854&r1=177853&r2=177854&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_atomic_msvc.h (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_atomic_msvc.h Mon Mar 25 04:23:30 2013
@@ -134,6 +134,27 @@ INLINE u16 atomic_exchange(volatile atom
   return v;
 }
 
+INLINE bool atomic_compare_exchange_strong(volatile atomic_uint8_t *a,
+                                           u8 *cmp,
+                                           u8 xchg,
+                                           memory_order mo) {
+  (void)mo;
+  DCHECK(!((uptr)a % sizeof(*a)));
+  u8 cmpv = *cmp;
+  u8 prev;
+  __asm {
+    mov al, cmpv
+    mov ecx, a
+    mov dl, xchg
+    lock cmpxchg [ecx], dl
+    mov prev, al
+  }
+  if (prev == cmpv)
+    return true;
+  *cmp = prev;
+  return false;
+}
+
 INLINE bool atomic_compare_exchange_strong(volatile atomic_uintptr_t *a,
                                            uptr *cmp,
                                            uptr xchg,
@@ -149,9 +170,9 @@ INLINE bool atomic_compare_exchange_stro
 
 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);
 }