Reapply: [oilpan]: Change marking to do precise roots first and conservative

Source/platform/heap/ThreadState.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 224 matching lines @@
     // Initialize threading infrastructure. Should be called from the main
     // thread.
     static void init();
     static void shutdown();
     static void shutdownHeapIfNecessary();
     bool isTerminating() { return m_isTerminating; }
 
     static void attachMainThread();
     static void detachMainThread();
 
-    // Trace all GC roots, called when marking the managed heap objects.
-    static void visitRoots(Visitor*);
+    // Trace all persistent roots, called when marking the managed heap objects.
+    static void visitPersistentRoots(Visitor*);
+
+    // Trace all objects found on the stack, used when doing conservative GCs.
+    static void visitStackRoots(Visitor*);
 
     // Associate ThreadState object with the current thread. After this
     // call thread can start using the garbage collected heap infrastructure.
     // It also has to periodically check for safepoints.
     static void attach();
 
     // Disassociate attached ThreadState from the current thread. The thread
     // can no longer use the garbage collected heap after this call.
     static void detach();
 
@@ skipping 245 matching lines @@
 #endif
 
     void pushWeakObjectPointerCallback(void*, WeakPointerCallback);
     bool popAndInvokeWeakPointerCallback(Visitor*);
 
     void getStats(HeapStats&);
     HeapStats& stats() { return m_stats; }
     HeapStats& statsAfterLastGC() { return m_statsAfterLastGC; }
 
     void setupHeapsForTermination();
-    void visitLocalRoots(Visitor*);
 
 private:
     explicit ThreadState();
     ~ThreadState();
 
     friend class SafePointBarrier;
     friend class SafePointAwareMutexLocker;
 
     void enterSafePoint(StackState, void*);
     NO_SANITIZE_ADDRESS void copyStackUntilSafePointScope();
@@ skipping 32 matching lines @@
 
     // We can't create a static member of type ThreadState here
     // because it will introduce global constructor and destructor.
     // We would like to manage lifetime of the ThreadState attached
     // to the main thread explicitly instead and still use normal
     // constructor and destructor for the ThreadState class.
     // For this we reserve static storage for the main ThreadState
     // and lazily construct ThreadState in it using placement new.
     static uint8_t s_mainThreadStateStorage[];
 
-    void trace(Visitor*);
-
     ThreadIdentifier m_thread;
     OwnPtr<PersistentNode> m_persistents;
     StackState m_stackState;
     intptr_t* m_startOfStack;
     intptr_t* m_endOfStack;
     void* m_safePointScopeMarker;
     Vector<Address> m_safePointStackCopy;
     bool m_atSafePoint;
     Vector<Interruptor*> m_interruptors;
     bool m_gcRequested;
@@ skipping 138 matching lines @@
     // HeapPage header. We use some of the bits to determine
     // whether the page is part of a terminting thread or
     // if the page is traced after being terminated (orphaned).
     uintptr_t m_terminating : 1;
     uintptr_t m_tracedAfterOrphaned : 1;
 };
 
 }
 
 #endif // ThreadState_h