From ef7d42fca18c16fbaf103822ad16f23246e2905d Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@google.com>
Date: Mon, 6 Jan 2014 12:55:46 -0800
Subject: Object model changes to support 64bit.

Modify mirror objects so that references between them use an ObjectReference
value type rather than an Object* so that functionality to compress larger
references can be captured in the ObjectRefererence implementation.
ObjectReferences are 32bit and all other aspects of object layout remain as
they are currently.

Expand fields in objects holding pointers so they can hold 64bit pointers. Its
expected the size of these will come down by improving where we hold compiler
meta-data.
Stub out x86_64 architecture specific runtime implementation.
Modify OutputStream so that reads and writes are of unsigned quantities.
Make the use of portable or quick code more explicit.
Templatize AtomicInteger to support more than just int32_t as a type.
Add missing, and fix issues relating to, missing annotalysis information on the
mutator lock.
Refactor and share implementations for array copy between System and uses
elsewhere in the runtime.
Fix numerous 64bit build issues.

Change-Id: I1a5694c251a42c9eff71084dfdd4b51fff716822
---
 runtime/mirror/object_reference.h | 91 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 runtime/mirror/object_reference.h

(limited to 'runtime/mirror/object_reference.h')

diff --git a/runtime/mirror/object_reference.h b/runtime/mirror/object_reference.h
new file mode 100644
index 0000000000..b30890f99a
--- /dev/null
+++ b/runtime/mirror/object_reference.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
+#define ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
+
+#include "locks.h"
+
+namespace art {
+namespace mirror {
+
+class Object;
+
+// Classes shared with the managed side of the world need to be packed so that they don't have
+// extra platform specific padding.
+#define MANAGED PACKED(4)
+
+// Value type representing a reference to a mirror::Object of type MirrorType.
+template<bool kPoisonReferences, class MirrorType>
+class MANAGED ObjectReference {
+ public:
+  MirrorType* AsMirrorPtr() const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    return UnCompress();
+  }
+
+  void Assign(MirrorType* other) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    reference_ = Compress(other);
+  }
+
+  void Clear() {
+    reference_ = 0;
+  }
+
+  uint32_t AsVRegValue() const {
+    return reference_;
+  }
+
+ protected:
+  ObjectReference<kPoisonReferences, MirrorType>(MirrorType* mirror_ptr)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
+      : reference_(Compress(mirror_ptr)) {
+  }
+
+  // Compress reference to its bit representation.
+  static uint32_t Compress(MirrorType* mirror_ptr) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    uintptr_t as_bits = reinterpret_cast<uintptr_t>(mirror_ptr);
+    return static_cast<uint32_t>(kPoisonReferences ? -as_bits : as_bits);
+  }
+
+  // Uncompress an encoded reference from its bit representation.
+  MirrorType* UnCompress() const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    uintptr_t as_bits = kPoisonReferences ? -reference_ : reference_;
+    return reinterpret_cast<MirrorType*>(as_bits);
+  }
+
+  friend class Object;
+
+  // The encoded reference to a mirror::Object.
+  uint32_t reference_;
+};
+
+// References between objects within the managed heap.
+template<class MirrorType>
+class MANAGED HeapReference : public ObjectReference<false, MirrorType> {
+ public:
+  static HeapReference<MirrorType> FromMirrorPtr(MirrorType* mirror_ptr)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
+    return HeapReference<MirrorType>(mirror_ptr);
+  }
+ private:
+  HeapReference<MirrorType>(MirrorType* mirror_ptr) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
+      : ObjectReference<false, MirrorType>(mirror_ptr) {}
+};
+
+}  // namespace mirror
+}  // namespace art
+
+#endif  // ART_RUNTIME_MIRROR_OBJECT_REFERENCE_H_
-- 
cgit v1.2.3-59-g8ed1b