Avoid strict-aliasing problems with Handles.

Replace use of reinterpret_cast with down_cast.

Bug: 18074773

Change-Id: Id42d462f2798f69a2210e5912f441c868b8b5812

1 files changed, 16 insertions, 24 deletions

diff --git a/runtime/handle_scope.h b/runtime/handle_scope.h
index f795e387f0..13c939fc3c 100644
--- a/runtime/handle_scope.h
+++ b/runtime/handle_scope.h
@@ -159,7 +159,7 @@ class HandleWrapper : public MutableHandle<T> {
   }
 
  private:
-  T** obj_;
+  T** const obj_;
 };
 
 // Scoped handle storage of a fixed size that is usually stack allocated.
@@ -169,31 +169,10 @@ class PACKED(4) StackHandleScope FINAL : public HandleScope {
   explicit StackHandleScope(Thread* self);
   ~StackHandleScope();
 
-  // Currently unused, using this GetReference instead of the one in HandleScope is preferred to
-  // avoid compiler optimizations incorrectly optimizing out of bound array accesses.
-  // TODO: Remove this when it is un-necessary.
-  ALWAYS_INLINE mirror::Object* GetReference(size_t i) const
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
-    DCHECK_LT(i, kNumReferences);
-    return GetReferences()[i].AsMirrorPtr();
-  }
-
-  ALWAYS_INLINE MutableHandle<mirror::Object> GetHandle(size_t i)
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
-    DCHECK_LT(i, kNumReferences);
-    return MutableHandle<mirror::Object>(&GetReferences()[i]);
-  }
-
-  ALWAYS_INLINE void SetReference(size_t i, mirror::Object* object)
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
-    DCHECK_LT(i, kNumReferences);
-    GetReferences()[i].Assign(object);
-  }
-
   template<class T>
   MutableHandle<T> NewHandle(T* object) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     SetReference(pos_, object);
-    MutableHandle<T> h(GetHandle(pos_));
+    MutableHandle<T> h(GetHandle<T>(pos_));
     pos_++;
     return h;
   }
@@ -201,12 +180,25 @@ class PACKED(4) StackHandleScope FINAL : public HandleScope {
   template<class T>
   HandleWrapper<T> NewHandleWrapper(T** object) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     SetReference(pos_, *object);
-    MutableHandle<T> h(GetHandle(pos_));
+    MutableHandle<T> h(GetHandle<T>(pos_));
     pos_++;
     return HandleWrapper<T>(object, h);
   }
 
  private:
+  template<class T>
+  ALWAYS_INLINE MutableHandle<T> GetHandle(size_t i)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    DCHECK_LT(i, kNumReferences);
+    return MutableHandle<T>(&GetReferences()[i]);
+  }
+
+  ALWAYS_INLINE void SetReference(size_t i, mirror::Object* object)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    DCHECK_LT(i, kNumReferences);
+    GetReferences()[i].Assign(object);
+  }
+
   // Reference storage needs to be first as expected by the HandleScope layout.
   StackReference<mirror::Object> storage_[kNumReferences];