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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 "gc/shared/barrierSetConfig.hpp"

#include "memory/memRegion.hpp"

#include "oops/access.hpp"

#include "oops/accessBackend.hpp"

#include "oops/oopsHierarchy.hpp"

#include "utilities/fakeRttiSupport.hpp"

class JavaThread;

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

// the rest of the system.

class BarrierSet: public CHeapObj<mtGC> {

  friend class VMStructs;

  static BarrierSet* _bs;

public:

  enum Name {

#define BARRIER_SET_DECLARE_BS_ENUM(bs_name) bs_name ,

    FOR_EACH_BARRIER_SET_DO(BARRIER_SET_DECLARE_BS_ENUM)

#undef BARRIER_SET_DECLARE_BS_ENUM

    UnknownBS

  };

  static BarrierSet* barrier_set() { return _bs; }

protected:

  // 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.

  typedef FakeRttiSupport<BarrierSet, Name> FakeRtti;

private:

  FakeRtti _fake_rtti;

public:

  // Metafunction mapping a class derived from BarrierSet to the

  // corresponding Name enum tag.

  template<typename T> struct GetName;

  // Metafunction mapping a Name enum type to the corresponding

  // lass derived from BarrierSet.

  template<BarrierSet::Name T> struct GetType;

  // 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:

  // 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);

  // Support for optimizing compilers to call the barrier set on slow path allocations

  // that did not enter a TLAB. Used for e.g. ReduceInitialCardMarks.

  // The allocation is safe to use iff it returns true. If not, the slow-path allocation

  // is redone until it succeeds. This can e.g. prevent allocations from the slow path

  // to be in old.

  virtual void on_slowpath_allocation_exit(JavaThread* thread, oop new_obj) {}

  virtual void on_thread_attach(JavaThread* thread) {}

  virtual void on_thread_detach(JavaThread* thread) {}

  virtual void make_parsable(JavaThread* thread) {}

protected:

  virtual void write_ref_array_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;

  static void set_bs(BarrierSet* bs) { _bs = bs; }

  // The AccessBarrier of a BarrierSet subclass is called by the Access API

  // (cf. oops/access.hpp) to perform decorated accesses. GC implementations

  // may override these default access operations by declaring an

  // AccessBarrier class in its BarrierSet. Its accessors will then be

  // automatically resolved at runtime.

  //

  // In order to register a new FooBarrierSet::AccessBarrier with the Access API,

  // the following steps should be taken:

  // 1) Provide an enum "name" for the BarrierSet in barrierSetConfig.hpp

  // 2) Make sure the barrier set headers are included from barrierSetConfig.inline.hpp

  // 3) Provide specializations for BarrierSet::GetName and BarrierSet::GetType.

  template <DecoratorSet decorators, typename BarrierSetT>

  class AccessBarrier: protected RawAccessBarrier<decorators> {

  private:

    typedef RawAccessBarrier<decorators> Raw;

  public:

    // Primitive heap accesses. These accessors get resolved when

    // IN_HEAP is set (e.g. when using the HeapAccess API), it is

    // not an oop_* overload, and the barrier strength is AS_NORMAL.

    template <typename T>

    static T load_in_heap(T* addr) {

      return Raw::template load<T>(addr);

    }

    template <typename T>

    static T load_in_heap_at(oop base, ptrdiff_t offset) {

      return Raw::template load_at<T>(base, offset);

    }

    template <typename T>

    static void store_in_heap(T* addr, T value) {

      Raw::store(addr, value);

    }

    template <typename T>

    static void store_in_heap_at(oop base, ptrdiff_t offset, T value) {

      Raw::store_at(base, offset, value);

    }

    template <typename T>

    static T atomic_cmpxchg_in_heap(T new_value, T* addr, T compare_value) {

      return Raw::atomic_cmpxchg(new_value, addr, compare_value);

    }

    template <typename T>

    static T atomic_cmpxchg_in_heap_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {

      return Raw::oop_atomic_cmpxchg_at(new_value, base, offset, compare_value);

    }

    template <typename T>

    static T atomic_xchg_in_heap(T new_value, T* addr) {

      return Raw::atomic_xchg(new_value, addr);

    }

    template <typename T>

    static T atomic_xchg_in_heap_at(T new_value, oop base, ptrdiff_t offset) {

      return Raw::atomic_xchg_at(new_value, base, offset);

    }

    template <typename T>

    static bool arraycopy_in_heap(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {

      return Raw::arraycopy(src_obj, dst_obj, src, dst, length);

    }

    // Heap oop accesses. These accessors get resolved when

    // IN_HEAP is set (e.g. when using the HeapAccess API), it is

    // an oop_* overload, and the barrier strength is AS_NORMAL.

    template <typename T>

    static oop oop_load_in_heap(T* addr) {

      return Raw::template oop_load<oop>(addr);

    }

    static oop oop_load_in_heap_at(oop base, ptrdiff_t offset) {

      return Raw::template oop_load_at<oop>(base, offset);

    }

    template <typename T>

    static void oop_store_in_heap(T* addr, oop value) {

      Raw::oop_store(addr, value);

    }

    static void oop_store_in_heap_at(oop base, ptrdiff_t offset, oop value) {

      Raw::oop_store_at(base, offset, value);

    }

    template <typename T>

    static oop oop_atomic_cmpxchg_in_heap(oop new_value, T* addr, oop compare_value) {

      return Raw::oop_atomic_cmpxchg(new_value, addr, compare_value);

    }

    static oop oop_atomic_cmpxchg_in_heap_at(oop new_value, oop base, ptrdiff_t offset, oop compare_value) {

      return Raw::oop_atomic_cmpxchg_at(new_value, base, offset, compare_value);

    }

    template <typename T>

    static oop oop_atomic_xchg_in_heap(oop new_value, T* addr) {

      return Raw::oop_atomic_xchg(new_value, addr);

    }

    static oop oop_atomic_xchg_in_heap_at(oop new_value, oop base, ptrdiff_t offset) {

      return Raw::oop_atomic_xchg_at(new_value, base, offset);

    }

    template <typename T>

    static bool oop_arraycopy_in_heap(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {

      return Raw::oop_arraycopy(src_obj, dst_obj, src, dst, length);

    }

    // Off-heap oop accesses. These accessors get resolved when

    // IN_HEAP is not set (e.g. when using the RootAccess API), it is

    // an oop* overload, and the barrier strength is AS_NORMAL.

    template <typename T>

    static oop oop_load_not_in_heap(T* addr) {

      return Raw::template oop_load<oop>(addr);

    }

    template <typename T>

    static void oop_store_not_in_heap(T* addr, oop value) {

      Raw::oop_store(addr, value);

    }

    template <typename T>

    static oop oop_atomic_cmpxchg_not_in_heap(oop new_value, T* addr, oop compare_value) {

      return Raw::oop_atomic_cmpxchg(new_value, addr, compare_value);

    }

    template <typename T>

    static oop oop_atomic_xchg_not_in_heap(oop new_value, T* addr) {

      return Raw::oop_atomic_xchg(new_value, addr);

    }

    // Clone barrier support

    static void clone_in_heap(oop src, oop dst, size_t size) {

      Raw::clone(src, dst, size);

    }

    static oop resolve(oop obj) {

      return Raw::resolve(obj);

    }

  };

};

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