Issue acquire barrier in SkRefCnt::unique().

include/core/SkRefCnt.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkRefCnt_DEFINED
@@ skipping 33 matching lines @@
 
     /** Return the reference count. Use only for debugging. */
     int32_t getRefCnt() const { return fRefCnt; }
 
     /** May return true if the caller is the only owner.
      *  Ensures that all previous owner's actions are complete.
      */
     bool unique() const {
         // We believe we're reading fRefCnt in a safe way here, so we stifle the TSAN warning about
         // an unproctected read.  Generally, don't read fRefCnt, and don't stifle this warning.
-        bool const unique = (1 == SK_ANNOTATE_UNPROTECTED_READ(fRefCnt));
+        bool const unique = (1 == sk_acquire_load(&fRefCnt));
         if (unique) {
             // Acquire barrier (L/SL), if not provided by load of fRefCnt.
             // Prevents user's 'unique' code from happening before decrements.
-            //TODO: issue the barrier.
+            //TODO: issue the barrier only when unique is true
         }
         return unique;
     }
 
     /** Increment the reference count. Must be balanced by a call to unref().
     */
     void ref() const {
         SkASSERT(fRefCnt > 0);
         sk_atomic_inc(&fRefCnt);  // No barrier required.
     }
@@ skipping 172 matching lines @@
 };
 // Can't use the #define trick below to guard a bare SkAutoTUnref(...) because it's templated. :(
 
 class SkAutoUnref : public SkAutoTUnref<SkRefCnt> {
 public:
     SkAutoUnref(SkRefCnt* obj) : SkAutoTUnref<SkRefCnt>(obj) {}
 };
 #define SkAutoUnref(...) SK_REQUIRE_LOCAL_VAR(SkAutoUnref)
 
 #endif