Reserve bits in the lock word for read barriers.

This prepares for the CC collector to use the standard object header
model by storing the read barrier state in the lock word.

Bug: 19355854
Bug: 12687968
Change-Id: Ia7585662dd2cebf0479a3e74f734afe5059fb70f

3 files changed, 2 insertions, 12 deletions

diff --git a/runtime/gc/collector/concurrent_copying.cc b/runtime/gc/collector/concurrent_copying.cc
index 734c935..057eed1 100644
--- a/runtime/gc/collector/concurrent_copying.cc
+++ b/runtime/gc/collector/concurrent_copying.cc
@@ -484,14 +484,6 @@ inline mirror::Object* ConcurrentCopying::GetFwdPtr(mirror::Object* from_ref) {
   }
 }
 
-inline void ConcurrentCopying::SetFwdPtr(mirror::Object* from_ref, mirror::Object* to_ref) {
-  DCHECK(region_space_->IsInFromSpace(from_ref));
-  DCHECK(region_space_->IsInToSpace(to_ref) || heap_->GetNonMovingSpace()->HasAddress(to_ref));
-  LockWord lw = from_ref->GetLockWord(false);
-  DCHECK_NE(lw.GetState(), LockWord::kForwardingAddress);
-  from_ref->SetLockWord(LockWord::FromForwardingAddress(reinterpret_cast<size_t>(to_ref)), false);
-}
-
 // The following visitors are that used to verify that there's no
 // references to the from-space left after marking.
 class ConcurrentCopyingVerifyNoFromSpaceRefsVisitor {
diff --git a/runtime/gc/collector/concurrent_copying.h b/runtime/gc/collector/concurrent_copying.h
index d0e0446..bbb551a 100644
--- a/runtime/gc/collector/concurrent_copying.h
+++ b/runtime/gc/collector/concurrent_copying.h
@@ -230,8 +230,6 @@ class ConcurrentCopying : public GarbageCollector {
   bool IsOnAllocStack(mirror::Object* ref) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
   mirror::Object* GetFwdPtr(mirror::Object* from_ref)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
-  void SetFwdPtr(mirror::Object* from_ref, mirror::Object* to_ref)
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
   void FlipThreadRoots() LOCKS_EXCLUDED(Locks::mutator_lock_);;
   void SwapStacks(Thread* self) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
   void RecordLiveStackFreezeSize(Thread* self);
diff --git a/runtime/gc/collector/mark_compact.cc b/runtime/gc/collector/mark_compact.cc
index 234bce5..d1ce0bc 100644
--- a/runtime/gc/collector/mark_compact.cc
+++ b/runtime/gc/collector/mark_compact.cc
@@ -91,7 +91,7 @@ void MarkCompact::ForwardObject(mirror::Object* obj) {
   const size_t alloc_size = RoundUp(obj->SizeOf(), space::BumpPointerSpace::kAlignment);
   LockWord lock_word = obj->GetLockWord(false);
   // If we have a non empty lock word, store it and restore it later.
-  if (lock_word.GetValue() != LockWord().GetValue()) {
+  if (!LockWord::IsDefault(lock_word)) {
     // Set the bit in the bitmap so that we know to restore it later.
     objects_with_lockword_->Set(obj);
     lock_words_to_restore_.push_back(lock_word);
@@ -509,7 +509,7 @@ void MarkCompact::MoveObject(mirror::Object* obj, size_t len) {
   // Use memmove since there may be overlap.
   memmove(reinterpret_cast<void*>(dest_addr), reinterpret_cast<const void*>(obj), len);
   // Restore the saved lock word if needed.
-  LockWord lock_word;
+  LockWord lock_word = LockWord::Default();
   if (UNLIKELY(objects_with_lockword_->Test(obj))) {
     lock_word = lock_words_to_restore_.front();
     lock_words_to_restore_.pop_front();