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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 *

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#ifndef SHARE_VM_GC_SHARED_BARRIERSET_HPP

#define SHARE_VM_GC_SHARED_BARRIERSET_HPP

#include "memory/memRegion.hpp"

#include "oops/oopsHierarchy.hpp"

#include "utilities/fakeRttiSupport.hpp"

// This class provides the interface between a barrier implementation and

// the rest of the system.

class BarrierSet: public CHeapObj<mtGC> {

  friend class VMStructs;

public:

  // Fake RTTI support.  For a derived class T to participate

  // - T must have a corresponding Name entry.

  // - GetName<T> must be specialized to return the corresponding Name

  //   entry.

  // - If T is a base class, the constructor must have a FakeRtti

  //   parameter and pass it up to its base class, with the tag set

  //   augmented with the corresponding Name entry.

  // - If T is a concrete class, the constructor must create a

  //   FakeRtti object whose tag set includes the corresponding Name

  //   entry, and pass it up to its base class.

  enum Name {                   // associated class

    ModRef,                     // ModRefBarrierSet

    CardTableModRef,            // CardTableModRefBS

    CardTableForRS,             // CardTableModRefBSForCTRS

    CardTableExtension,         // CardTableExtension

    G1SATBCT,                   // G1SATBCardTableModRefBS

    G1SATBCTLogging             // G1SATBCardTableLoggingModRefBS

  };

protected:

  typedef FakeRttiSupport<BarrierSet, Name> FakeRtti;

private:

  FakeRtti _fake_rtti;

  // Metafunction mapping a class derived from BarrierSet to the

  // corresponding Name enum tag.

  template<typename T> struct GetName;

  // Downcast argument to a derived barrier set type.

  // The cast is checked in a debug build.

  // T must have a specialization for BarrierSet::GetName<T>.

  template<typename T> friend T* barrier_set_cast(BarrierSet* bs);

public:

  // Note: This is not presently the Name corresponding to the

  // concrete class of this object.

  BarrierSet::Name kind() const { return _fake_rtti.concrete_tag(); }

  // Test whether this object is of the type corresponding to bsn.

  bool is_a(BarrierSet::Name bsn) const { return _fake_rtti.has_tag(bsn); }

  // End of fake RTTI support.

protected:

  BarrierSet(const FakeRtti& fake_rtti) : _fake_rtti(fake_rtti) { }

  ~BarrierSet() { }

public:

  // Invoke the barrier, if any, necessary when writing "new_val" into the

  // ref field at "offset" in "obj".

  // (For efficiency reasons, this operation is specialized for certain

  // barrier types.  Semantically, it should be thought of as a call to the

  // virtual "_work" function below, which must implement the barrier.)

  // First the pre-write versions...

  template <class T> inline void write_ref_field_pre(T* field, oop new_val);

  // ...then the post-write version.

  inline void write_ref_field(void* field, oop new_val, bool release = false);

protected:

  virtual void write_ref_field_pre_work(      oop* field, oop new_val) {};

  virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};

  virtual void write_ref_field_work(void* field, oop new_val, bool release) = 0;

public:

  // Operations on arrays, or general regions (e.g., for "clone") may be

  // optimized by some barriers.

  // Below length is the # array elements being written

  virtual void write_ref_array_pre(oop* dst, int length,

                                   bool dest_uninitialized = false) {}

  virtual void write_ref_array_pre(narrowOop* dst, int length,

                                   bool dest_uninitialized = false) {}

  // Below count is the # array elements being written, starting

  // at the address "start", which may not necessarily be HeapWord-aligned

  inline void write_ref_array(HeapWord* start, size_t count);

  // Static versions, suitable for calling from generated code;

  // count is # array elements being written, starting with "start",

  // which may not necessarily be HeapWord-aligned.

  static void static_write_ref_array_pre(HeapWord* start, size_t count);

  static void static_write_ref_array_post(HeapWord* start, size_t count);

protected:

  virtual void write_ref_array_work(MemRegion mr) = 0;

public:

  // (For efficiency reasons, this operation is specialized for certain

  // barrier types.  Semantically, it should be thought of as a call to the

  // virtual "_work" function below, which must implement the barrier.)

  void write_region(MemRegion mr);

protected:

  virtual void write_region_work(MemRegion mr) = 0;

public:

  // Inform the BarrierSet that the the covered heap region that starts

  // with "base" has been changed to have the given size (possibly from 0,

  // for initialization.)

  virtual void resize_covered_region(MemRegion new_region) = 0;

  // If the barrier set imposes any alignment restrictions on boundaries

  // within the heap, this function tells whether they are met.

  virtual bool is_aligned(HeapWord* addr) = 0;

  // Print a description of the memory for the barrier set

  virtual void print_on(outputStream* st) const = 0;

};

template<typename T>

inline T* barrier_set_cast(BarrierSet* bs) {

  assert(bs->is_a(BarrierSet::GetName<T>::value), "wrong type of barrier set");

  return static_cast<T*>(bs);

}

#endif // SHARE_VM_GC_SHARED_BARRIERSET_HPP