1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_VM_GC_SHARED_BARRIERSET_HPP
  26 #define SHARE_VM_GC_SHARED_BARRIERSET_HPP
  27 
  28 #include "gc/shared/barrierSetConfig.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "oops/access.hpp"
  31 #include "oops/accessBackend.hpp"
  32 #include "oops/oopsHierarchy.hpp"
  33 #include "utilities/fakeRttiSupport.hpp"
  34 
  35 class JavaThread;
  36 
  37 // This class provides the interface between a barrier implementation and
  38 // the rest of the system.
  39 
  40 class BarrierSet: public CHeapObj<mtGC> {
  41   friend class VMStructs;
  42 
  43   static BarrierSet* _bs;
  44 
  45 public:
  46   enum Name {
  47 #define BARRIER_SET_DECLARE_BS_ENUM(bs_name) bs_name ,
  48     FOR_EACH_BARRIER_SET_DO(BARRIER_SET_DECLARE_BS_ENUM)
  49 #undef BARRIER_SET_DECLARE_BS_ENUM
  50     UnknownBS
  51   };
  52 
  53   static BarrierSet* barrier_set() { return _bs; }
  54 
  55 protected:
  56   // Fake RTTI support.  For a derived class T to participate
  57   // - T must have a corresponding Name entry.
  58   // - GetName<T> must be specialized to return the corresponding Name
  59   //   entry.
  60   // - If T is a base class, the constructor must have a FakeRtti
  61   //   parameter and pass it up to its base class, with the tag set
  62   //   augmented with the corresponding Name entry.
  63   // - If T is a concrete class, the constructor must create a
  64   //   FakeRtti object whose tag set includes the corresponding Name
  65   //   entry, and pass it up to its base class.
  66   typedef FakeRttiSupport<BarrierSet, Name> FakeRtti;
  67 
  68 private:
  69   FakeRtti _fake_rtti;
  70 
  71 public:
  72   // Metafunction mapping a class derived from BarrierSet to the
  73   // corresponding Name enum tag.
  74   template<typename T> struct GetName;
  75 
  76   // Metafunction mapping a Name enum type to the corresponding
  77   // lass derived from BarrierSet.
  78   template<BarrierSet::Name T> struct GetType;
  79 
  80   // Note: This is not presently the Name corresponding to the
  81   // concrete class of this object.
  82   BarrierSet::Name kind() const { return _fake_rtti.concrete_tag(); }
  83 
  84   // Test whether this object is of the type corresponding to bsn.
  85   bool is_a(BarrierSet::Name bsn) const { return _fake_rtti.has_tag(bsn); }
  86 
  87   // End of fake RTTI support.
  88 
  89 protected:
  90   BarrierSet(const FakeRtti& fake_rtti) : _fake_rtti(fake_rtti) { }
  91   ~BarrierSet() { }
  92 
  93 public:
  94   // Operations on arrays, or general regions (e.g., for "clone") may be
  95   // optimized by some barriers.
  96 
  97   // Below length is the # array elements being written
  98   virtual void write_ref_array_pre(oop* dst, int length,
  99                                    bool dest_uninitialized = false) {}
 100   virtual void write_ref_array_pre(narrowOop* dst, int length,
 101                                    bool dest_uninitialized = false) {}
 102   // Below count is the # array elements being written, starting
 103   // at the address "start", which may not necessarily be HeapWord-aligned
 104   inline void write_ref_array(HeapWord* start, size_t count);
 105 
 106   // Static versions, suitable for calling from generated code;
 107   // count is # array elements being written, starting with "start",
 108   // which may not necessarily be HeapWord-aligned.
 109   static void static_write_ref_array_pre(HeapWord* start, size_t count);
 110   static void static_write_ref_array_post(HeapWord* start, size_t count);
 111 
 112   // Support for optimizing compilers to call the barrier set on slow path allocations
 113   // that did not enter a TLAB. Used for e.g. ReduceInitialCardMarks.
 114   // The allocation is safe to use iff it returns true. If not, the slow-path allocation
 115   // is redone until it succeeds. This can e.g. prevent allocations from the slow path
 116   // to be in old.
 117   virtual void on_slowpath_allocation_exit(JavaThread* thread, oop new_obj) {}
 118   virtual void on_thread_attach(JavaThread* thread) {}
 119   virtual void on_thread_detach(JavaThread* thread) {}
 120   virtual void make_parsable(JavaThread* thread) {}
 121 
 122 protected:
 123   virtual void write_ref_array_work(MemRegion mr) = 0;
 124 
 125 public:
 126   // Print a description of the memory for the barrier set
 127   virtual void print_on(outputStream* st) const = 0;
 128 
 129   static void set_bs(BarrierSet* bs) { _bs = bs; }
 130 
 131   // The AccessBarrier of a BarrierSet subclass is called by the Access API
 132   // (cf. oops/access.hpp) to perform decorated accesses. GC implementations
 133   // may override these default access operations by declaring an
 134   // AccessBarrier class in its BarrierSet. Its accessors will then be
 135   // automatically resolved at runtime.
 136   //
 137   // In order to register a new FooBarrierSet::AccessBarrier with the Access API,
 138   // the following steps should be taken:
 139   // 1) Provide an enum "name" for the BarrierSet in barrierSetConfig.hpp
 140   // 2) Make sure the barrier set headers are included from barrierSetConfig.inline.hpp
 141   // 3) Provide specializations for BarrierSet::GetName and BarrierSet::GetType.
 142   template <DecoratorSet decorators, typename BarrierSetT>
 143   class AccessBarrier: protected RawAccessBarrier<decorators> {
 144   private:
 145     typedef RawAccessBarrier<decorators> Raw;
 146 
 147   public:
 148     // Primitive heap accesses. These accessors get resolved when
 149     // IN_HEAP is set (e.g. when using the HeapAccess API), it is
 150     // not an oop_* overload, and the barrier strength is AS_NORMAL.
 151     template <typename T>
 152     static T load_in_heap(T* addr) {
 153       return Raw::template load<T>(addr);
 154     }
 155 
 156     template <typename T>
 157     static T load_in_heap_at(oop base, ptrdiff_t offset) {
 158       return Raw::template load_at<T>(base, offset);
 159     }
 160 
 161     template <typename T>
 162     static void store_in_heap(T* addr, T value) {
 163       Raw::store(addr, value);
 164     }
 165 
 166     template <typename T>
 167     static void store_in_heap_at(oop base, ptrdiff_t offset, T value) {
 168       Raw::store_at(base, offset, value);
 169     }
 170 
 171     template <typename T>
 172     static T atomic_cmpxchg_in_heap(T new_value, T* addr, T compare_value) {
 173       return Raw::atomic_cmpxchg(new_value, addr, compare_value);
 174     }
 175 
 176     template <typename T>
 177     static T atomic_cmpxchg_in_heap_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {
 178       return Raw::oop_atomic_cmpxchg_at(new_value, base, offset, compare_value);
 179     }
 180 
 181     template <typename T>
 182     static T atomic_xchg_in_heap(T new_value, T* addr) {
 183       return Raw::atomic_xchg(new_value, addr);
 184     }
 185 
 186     template <typename T>
 187     static T atomic_xchg_in_heap_at(T new_value, oop base, ptrdiff_t offset) {
 188       return Raw::atomic_xchg_at(new_value, base, offset);
 189     }
 190 
 191     template <typename T>
 192     static bool arraycopy_in_heap(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {
 193       return Raw::arraycopy(src_obj, dst_obj, src, dst, length);
 194     }
 195 
 196     // Heap oop accesses. These accessors get resolved when
 197     // IN_HEAP is set (e.g. when using the HeapAccess API), it is
 198     // an oop_* overload, and the barrier strength is AS_NORMAL.
 199     template <typename T>
 200     static oop oop_load_in_heap(T* addr) {
 201       return Raw::template oop_load<oop>(addr);
 202     }
 203 
 204     static oop oop_load_in_heap_at(oop base, ptrdiff_t offset) {
 205       return Raw::template oop_load_at<oop>(base, offset);
 206     }
 207 
 208     template <typename T>
 209     static void oop_store_in_heap(T* addr, oop value) {
 210       Raw::oop_store(addr, value);
 211     }
 212 
 213     static void oop_store_in_heap_at(oop base, ptrdiff_t offset, oop value) {
 214       Raw::oop_store_at(base, offset, value);
 215     }
 216 
 217     template <typename T>
 218     static oop oop_atomic_cmpxchg_in_heap(oop new_value, T* addr, oop compare_value) {
 219       return Raw::oop_atomic_cmpxchg(new_value, addr, compare_value);
 220     }
 221 
 222     static oop oop_atomic_cmpxchg_in_heap_at(oop new_value, oop base, ptrdiff_t offset, oop compare_value) {
 223       return Raw::oop_atomic_cmpxchg_at(new_value, base, offset, compare_value);
 224     }
 225 
 226     template <typename T>
 227     static oop oop_atomic_xchg_in_heap(oop new_value, T* addr) {
 228       return Raw::oop_atomic_xchg(new_value, addr);
 229     }
 230 
 231     static oop oop_atomic_xchg_in_heap_at(oop new_value, oop base, ptrdiff_t offset) {
 232       return Raw::oop_atomic_xchg_at(new_value, base, offset);
 233     }
 234 
 235     template <typename T>
 236     static bool oop_arraycopy_in_heap(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {
 237       return Raw::oop_arraycopy(src_obj, dst_obj, src, dst, length);
 238     }
 239 
 240     // Off-heap oop accesses. These accessors get resolved when
 241     // IN_HEAP is not set (e.g. when using the RootAccess API), it is
 242     // an oop* overload, and the barrier strength is AS_NORMAL.
 243     template <typename T>
 244     static oop oop_load_not_in_heap(T* addr) {
 245       return Raw::template oop_load<oop>(addr);
 246     }
 247 
 248     template <typename T>
 249     static void oop_store_not_in_heap(T* addr, oop value) {
 250       Raw::oop_store(addr, value);
 251     }
 252 
 253     template <typename T>
 254     static oop oop_atomic_cmpxchg_not_in_heap(oop new_value, T* addr, oop compare_value) {
 255       return Raw::oop_atomic_cmpxchg(new_value, addr, compare_value);
 256     }
 257 
 258     template <typename T>
 259     static oop oop_atomic_xchg_not_in_heap(oop new_value, T* addr) {
 260       return Raw::oop_atomic_xchg(new_value, addr);
 261     }
 262 
 263     // Clone barrier support
 264     static void clone_in_heap(oop src, oop dst, size_t size) {
 265       Raw::clone(src, dst, size);
 266     }
 267 
 268     static oop resolve(oop obj) {
 269       return Raw::resolve(obj);
 270     }
 271   };
 272 };
 273 
 274 template<typename T>
 275 inline T* barrier_set_cast(BarrierSet* bs) {
 276   assert(bs->is_a(BarrierSet::GetName<T>::value), "wrong type of barrier set");
 277   return static_cast<T*>(bs);
 278 }
 279 
 280 #endif // SHARE_VM_GC_SHARED_BARRIERSET_HPP