Clean up the runtime read barrier and fix fake address dependency.

- Rename GetReadBarrierPointer to GetReadBarrierState.
- Change its return type to uint32_t.
- Fix the runtime fake address dependency for arm/arm64 using inline
  asm.
- Drop ReadBarrier::black_ptr_ and some brooks code.

Bug: 12687968
Test: test-art with CC, Ritz EAAC, libartd boot on N9.
Change-Id: I595970db825db5be2e98ee1fcbd7696d5501af55
diff --git a/runtime/gc/reference_queue.cc b/runtime/gc/reference_queue.cc
index 4e6f7da..a0eb197 100644
--- a/runtime/gc/reference_queue.cc
+++ b/runtime/gc/reference_queue.cc
@@ -75,19 +75,19 @@
     // collector (SemiSpace) is running.
     CHECK(ref != nullptr);
     collector::ConcurrentCopying* concurrent_copying = heap->ConcurrentCopyingCollector();
-    mirror::Object* rb_ptr = ref->GetReadBarrierPointer();
-    if (rb_ptr == ReadBarrier::GrayPtr()) {
-      ref->AtomicSetReadBarrierPointer(ReadBarrier::GrayPtr(), ReadBarrier::WhitePtr());
-      CHECK_EQ(ref->GetReadBarrierPointer(), ReadBarrier::WhitePtr());
+    uint32_t rb_state = ref->GetReadBarrierState();
+    if (rb_state == ReadBarrier::GrayState()) {
+      ref->AtomicSetReadBarrierState(ReadBarrier::GrayState(), ReadBarrier::WhiteState());
+      CHECK_EQ(ref->GetReadBarrierState(), ReadBarrier::WhiteState());
     } else {
       // In ConcurrentCopying::ProcessMarkStackRef() we may leave a white reference in the queue and
       // find it here, which is OK.
-      CHECK_EQ(rb_ptr, ReadBarrier::WhitePtr()) << "ref=" << ref << " rb_ptr=" << rb_ptr;
+      CHECK_EQ(rb_state, ReadBarrier::WhiteState()) << "ref=" << ref << " rb_state=" << rb_state;
       ObjPtr<mirror::Object> referent = ref->GetReferent<kWithoutReadBarrier>();
       // The referent could be null if it's cleared by a mutator (Reference.clear()).
       if (referent != nullptr) {
         CHECK(concurrent_copying->IsInToSpace(referent.Ptr()))
-            << "ref=" << ref << " rb_ptr=" << ref->GetReadBarrierPointer()
+            << "ref=" << ref << " rb_state=" << ref->GetReadBarrierState()
             << " referent=" << referent;
       }
     }