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
diff --git a/runtime/atomic.h b/runtime/atomic.h
index b1e9870..2a47e46 100644
--- a/runtime/atomic.h
+++ b/runtime/atomic.h
@@ -26,6 +26,69 @@
 
 class Mutex;
 
+template<typename T>
+class Atomic {
+ public:
+  Atomic<T>() : value_(0) { }
+
+  explicit Atomic<T>(T value) : value_(value) { }
+
+  Atomic<T>& operator=(T desired) {
+    Store(desired);
+    return *this;
+  }
+
+  T Load() const {
+    return value_;
+  }
+
+  operator T() const {
+    return Load();
+  }
+
+  T FetchAndAdd(const T value) {
+    return __sync_fetch_and_add(&value_, value);  // Return old_value.
+  }
+
+  T FetchAndSub(const T value) {
+    return __sync_fetch_and_sub(&value_, value);  // Return old value.
+  }
+
+  T operator++() {  // Prefix operator.
+    return __sync_add_and_fetch(&value_, 1);  // Return new value.
+  }
+
+  T operator++(int) {  // Postfix operator.
+    return __sync_fetch_and_add(&value_, 1);  // Return old value.
+  }
+
+  T operator--() {  // Prefix operator.
+    return __sync_sub_and_fetch(&value_, 1);  // Return new value.
+  }
+
+  T operator--(int) {  // Postfix operator.
+    return __sync_fetch_and_sub(&value_, 1);  // Return old value.
+  }
+
+  bool CompareAndSwap(T expected_value, T desired_value) {
+    return __sync_bool_compare_and_swap(&value_, expected_value, desired_value);
+  }
+
+  volatile T* Address() {
+    return &value_;
+  }
+
+ private:
+  // Unsafe = operator for non atomic operations on the integer.
+  void Store(T desired) {
+    value_ = desired;
+  }
+
+  volatile T value_;
+};
+
+typedef Atomic<int32_t> AtomicInteger;
+
 // NOTE: Two "quasiatomic" operations on the exact same memory address
 // are guaranteed to operate atomically with respect to each other,
 // but no guarantees are made about quasiatomic operations mixed with
@@ -80,7 +143,7 @@
   static void MembarLoadStore() {
   #if defined(__arm__)
     __asm__ __volatile__("dmb ish" : : : "memory");
-  #elif defined(__i386__)
+  #elif defined(__i386__) || defined(__x86_64__)
     __asm__ __volatile__("" : : : "memory");
   #elif defined(__mips__)
     __asm__ __volatile__("sync" : : : "memory");
@@ -92,7 +155,7 @@
   static void MembarLoadLoad() {
   #if defined(__arm__)
     __asm__ __volatile__("dmb ish" : : : "memory");
-  #elif defined(__i386__)
+  #elif defined(__i386__) || defined(__x86_64__)
     __asm__ __volatile__("" : : : "memory");
   #elif defined(__mips__)
     __asm__ __volatile__("sync" : : : "memory");
@@ -104,7 +167,7 @@
   static void MembarStoreStore() {
   #if defined(__arm__)
     __asm__ __volatile__("dmb ishst" : : : "memory");
-  #elif defined(__i386__)
+  #elif defined(__i386__) || defined(__x86_64__)
     __asm__ __volatile__("" : : : "memory");
   #elif defined(__mips__)
     __asm__ __volatile__("sync" : : : "memory");
@@ -116,7 +179,7 @@
   static void MembarStoreLoad() {
   #if defined(__arm__)
     __asm__ __volatile__("dmb ish" : : : "memory");
-  #elif defined(__i386__)
+  #elif defined(__i386__) || defined(__x86_64__)
     __asm__ __volatile__("mfence" : : : "memory");
   #elif defined(__mips__)
     __asm__ __volatile__("sync" : : : "memory");