1 /*
  2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 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).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #ifndef SHARE_VM_MEMORY_UNIVERSE_HPP
 26 #define SHARE_VM_MEMORY_UNIVERSE_HPP
 27 
 28 #include "oops/array.hpp"
 29 #include "runtime/handles.hpp"
 30 #include "utilities/growableArray.hpp"
 31 
 32 // Universe is a name space holding known system classes and objects in the VM.
 33 //
 34 // Loaded classes are accessible through the SystemDictionary.
 35 //
 36 // The object heap is allocated and accessed through Universe, and various allocation
 37 // support is provided. Allocation by the interpreter and compiled code is done inline
 38 // and bails out to Scavenge::invoke_and_allocate.
 39 
 40 class CollectedHeap;
 41 class DeferredObjAllocEvent;
 42 
 43 
 44 // A helper class for caching a Method* when the user of the cache
 45 // only cares about the latest version of the Method*.  This cache safely
 46 // interacts with the RedefineClasses API.
 47 
 48 class LatestMethodCache : public CHeapObj<mtClass> {
 49   // We save the Klass* and the idnum of Method* in order to get
 50   // the current cached Method*.
 51  private:
 52   Klass*                _klass;
 53   int                   _method_idnum;
 54 
 55  public:
 56   LatestMethodCache()   { _klass = NULL; _method_idnum = -1; }
 57   ~LatestMethodCache()  { _klass = NULL; _method_idnum = -1; }
 58 
 59   void   init(Klass* k, Method* m);
 60   Klass* klass() const           { return _klass; }
 61   int    method_idnum() const    { return _method_idnum; }
 62 
 63   Method* get_method();
 64 
 65   // CDS support.  Replace the klass in this with the archive version
 66   // could use this for Enhanced Class Redefinition also.
 67   void serialize(SerializeClosure* f) {
 68     f->do_ptr((void**)&_klass);
 69   }
 70   void metaspace_pointers_do(MetaspaceClosure* it);
 71 };
 72 
 73 
 74 // For UseCompressedOops.
 75 struct NarrowPtrStruct {
 76   // Base address for oop-within-java-object materialization.
 77   // NULL if using wide oops or zero based narrow oops.
 78   address _base;
 79   // Number of shift bits for encoding/decoding narrow ptrs.
 80   // 0 if using wide ptrs or zero based unscaled narrow ptrs,
 81   // LogMinObjAlignmentInBytes/LogKlassAlignmentInBytes otherwise.
 82   int     _shift;
 83   // Generate code with implicit null checks for narrow ptrs.
 84   bool    _use_implicit_null_checks;
 85 };
 86 
 87 enum VerifyOption {
 88       VerifyOption_Default = 0,
 89 
 90       // G1
 91       VerifyOption_G1UsePrevMarking = VerifyOption_Default,
 92       VerifyOption_G1UseNextMarking = VerifyOption_G1UsePrevMarking + 1,
 93       VerifyOption_G1UseFullMarking = VerifyOption_G1UseNextMarking + 1
 94 };
 95 
 96 class Universe: AllStatic {
 97   // Ugh.  Universe is much too friendly.
 98   friend class MarkSweep;
 99   friend class oopDesc;
100   friend class ClassLoader;
101   friend class SystemDictionary;
102   friend class ReservedHeapSpace;
103   friend class VMStructs;
104   friend class VM_PopulateDumpSharedSpace;
105   friend class Metaspace;
106   friend class MetaspaceShared;
107 
108   friend jint  universe_init();
109   friend void  universe2_init();
110   friend bool  universe_post_init();
111   friend void  universe_post_module_init();
112 
113  private:
114   // Known classes in the VM
115   static Klass* _typeArrayKlassObjs[T_LONG+1];
116   static Klass* _objectArrayKlassObj;
117 
118   // Known objects in the VM
119 
120   // Primitive objects
121   static oop _int_mirror;
122   static oop _float_mirror;
123   static oop _double_mirror;
124   static oop _byte_mirror;
125   static oop _bool_mirror;
126   static oop _char_mirror;
127   static oop _long_mirror;
128   static oop _short_mirror;
129   static oop _void_mirror;
130 
131   static oop          _main_thread_group;             // Reference to the main thread group object
132   static oop          _system_thread_group;           // Reference to the system thread group object
133 
134   static objArrayOop  _the_empty_class_klass_array;   // Canonicalized obj array of type java.lang.Class
135   static oop          _the_null_sentinel;             // A unique object pointer unused except as a sentinel for null.
136   static oop          _the_null_string;               // A cache of "null" as a Java string
137   static oop          _the_min_jint_string;          // A cache of "-2147483648" as a Java string
138   static LatestMethodCache* _finalizer_register_cache; // static method for registering finalizable objects
139   static LatestMethodCache* _loader_addClass_cache;    // method for registering loaded classes in class loader vector
140   static LatestMethodCache* _pd_implies_cache;         // method for checking protection domain attributes
141   static LatestMethodCache* _throw_illegal_access_error_cache; // Unsafe.throwIllegalAccessError() method
142   static LatestMethodCache* _do_stack_walk_cache;      // method for stack walker callback
143 
144   // preallocated error objects (no backtrace)
145   static oop          _out_of_memory_error_java_heap;
146   static oop          _out_of_memory_error_metaspace;
147   static oop          _out_of_memory_error_class_metaspace;
148   static oop          _out_of_memory_error_array_size;
149   static oop          _out_of_memory_error_gc_overhead_limit;
150   static oop          _out_of_memory_error_realloc_objects;
151   static oop          _out_of_memory_error_retry;
152 
153   // preallocated cause message for delayed StackOverflowError
154   static oop          _delayed_stack_overflow_error_message;
155 
156   static Array<int>*            _the_empty_int_array;            // Canonicalized int array
157   static Array<u2>*             _the_empty_short_array;          // Canonicalized short array
158   static Array<Klass*>*         _the_empty_klass_array;          // Canonicalized klass array
159   static Array<InstanceKlass*>* _the_empty_instance_klass_array; // Canonicalized instance klass array
160   static Array<Method*>*        _the_empty_method_array;         // Canonicalized method array
161 
162   static Array<Klass*>*  _the_array_interfaces_array;
163 
164   // array of preallocated error objects with backtrace
165   static objArrayOop   _preallocated_out_of_memory_error_array;
166 
167   // number of preallocated error objects available for use
168   static volatile jint _preallocated_out_of_memory_error_avail_count;
169 
170   static oop          _null_ptr_exception_instance;   // preallocated exception object
171   static oop          _arithmetic_exception_instance; // preallocated exception object
172   static oop          _virtual_machine_error_instance; // preallocated exception object
173   // The object used as an exception dummy when exceptions are thrown for
174   // the vm thread.
175   static oop          _vm_exception;
176 
177   // References waiting to be transferred to the ReferenceHandler
178   static oop          _reference_pending_list;
179 
180   // The particular choice of collected heap.
181   static CollectedHeap* _collectedHeap;
182 
183   static intptr_t _non_oop_bits;
184 
185   // For UseCompressedOops.
186   static struct NarrowPtrStruct _narrow_oop;
187   // For UseCompressedClassPointers.
188   static struct NarrowPtrStruct _narrow_klass;
189   static address _narrow_ptrs_base;
190   // CompressedClassSpaceSize set to 1GB, but appear 3GB away from _narrow_ptrs_base during CDS dump.
191   static uint64_t _narrow_klass_range;
192   // array of dummy objects used with +FullGCAlot
193   debug_only(static objArrayOop _fullgc_alot_dummy_array;)
194   // index of next entry to clear
195   debug_only(static int         _fullgc_alot_dummy_next;)
196 
197   // Compiler/dispatch support
198   static int  _base_vtable_size;                      // Java vtbl size of klass Object (in words)
199 
200   // Initialization
201   static bool _bootstrapping;                         // true during genesis
202   static bool _module_initialized;                    // true after call_initPhase2 called
203   static bool _fully_initialized;                     // true after universe_init and initialize_vtables called
204 
205   // the array of preallocated errors with backtraces
206   static objArrayOop  preallocated_out_of_memory_errors()     { return _preallocated_out_of_memory_error_array; }
207 
208   // generate an out of memory error; if possible using an error with preallocated backtrace;
209   // otherwise return the given default error.
210   static oop        gen_out_of_memory_error(oop default_err);
211 
212   // Historic gc information
213   static size_t _heap_capacity_at_last_gc;
214   static size_t _heap_used_at_last_gc;
215 
216   static CollectedHeap* create_heap();
217   static jint initialize_heap();
218   static void initialize_basic_type_mirrors(TRAPS);
219   static void fixup_mirrors(TRAPS);
220 
221   static void reinitialize_vtable_of(Klass* k, TRAPS);
222   static void reinitialize_itables(TRAPS);
223   static void compute_base_vtable_size();             // compute vtable size of class Object
224 
225   static void genesis(TRAPS);                         // Create the initial world
226 
227   // Mirrors for primitive classes (created eagerly)
228   static oop check_mirror(oop m) {
229     assert(m != NULL, "mirror not initialized");
230     return m;
231   }
232 
233   static void     set_narrow_oop_base(address base) {
234     assert(UseCompressedOops, "no compressed oops?");
235     _narrow_oop._base    = base;
236   }
237   static void     set_narrow_klass_base(address base) {
238     assert(UseCompressedClassPointers, "no compressed klass ptrs?");
239     _narrow_klass._base   = base;
240   }
241   static void     set_narrow_klass_range(uint64_t range) {
242      assert(UseCompressedClassPointers, "no compressed klass ptrs?");
243      _narrow_klass_range = range;
244   }
245   static void     set_narrow_oop_use_implicit_null_checks(bool use) {
246     assert(UseCompressedOops, "no compressed ptrs?");
247     _narrow_oop._use_implicit_null_checks   = use;
248   }
249 
250   // Debugging
251   static int _verify_count;                           // number of verifies done
252 
253   // True during call to verify().  Should only be set/cleared in verify().
254   static bool _verify_in_progress;
255   static long verify_flags;
256 
257   static uintptr_t _verify_oop_mask;
258   static uintptr_t _verify_oop_bits;
259 
260   static void calculate_verify_data(HeapWord* low_boundary, HeapWord* high_boundary) PRODUCT_RETURN;
261   static void compute_verify_oop_data();
262 
263  public:
264   // Known classes in the VM
265   static Klass* boolArrayKlassObj()                 { return typeArrayKlassObj(T_BOOLEAN); }
266   static Klass* byteArrayKlassObj()                 { return typeArrayKlassObj(T_BYTE); }
267   static Klass* charArrayKlassObj()                 { return typeArrayKlassObj(T_CHAR); }
268   static Klass* intArrayKlassObj()                  { return typeArrayKlassObj(T_INT); }
269   static Klass* shortArrayKlassObj()                { return typeArrayKlassObj(T_SHORT); }
270   static Klass* longArrayKlassObj()                 { return typeArrayKlassObj(T_LONG); }
271   static Klass* floatArrayKlassObj()                { return typeArrayKlassObj(T_FLOAT); }
272   static Klass* doubleArrayKlassObj()               { return typeArrayKlassObj(T_DOUBLE); }
273 
274   static Klass* objectArrayKlassObj()               { return _objectArrayKlassObj; }
275 
276   static Klass* typeArrayKlassObj(BasicType t) {
277     assert((uint)t >= T_BOOLEAN, "range check for type: %s", type2name(t));
278     assert((uint)t < T_LONG+1,   "range check for type: %s", type2name(t));
279     assert(_typeArrayKlassObjs[t] != NULL, "domain check");
280     return _typeArrayKlassObjs[t];
281   }
282 
283   // Known objects in the VM
284   static oop int_mirror()                   { return check_mirror(_int_mirror); }
285   static oop float_mirror()                 { return check_mirror(_float_mirror); }
286   static oop double_mirror()                { return check_mirror(_double_mirror); }
287   static oop byte_mirror()                  { return check_mirror(_byte_mirror); }
288   static oop bool_mirror()                  { return check_mirror(_bool_mirror); }
289   static oop char_mirror()                  { return check_mirror(_char_mirror); }
290   static oop long_mirror()                  { return check_mirror(_long_mirror); }
291   static oop short_mirror()                 { return check_mirror(_short_mirror); }
292   static oop void_mirror()                  { return check_mirror(_void_mirror); }
293 
294   static void set_int_mirror(oop m)         { _int_mirror = m;    }
295   static void set_float_mirror(oop m)       { _float_mirror = m;  }
296   static void set_double_mirror(oop m)      { _double_mirror = m; }
297   static void set_byte_mirror(oop m)        { _byte_mirror = m;   }
298   static void set_bool_mirror(oop m)        { _bool_mirror = m;   }
299   static void set_char_mirror(oop m)        { _char_mirror = m;   }
300   static void set_long_mirror(oop m)        { _long_mirror = m;   }
301   static void set_short_mirror(oop m)       { _short_mirror = m;  }
302   static void set_void_mirror(oop m)        { _void_mirror = m;   }
303 
304   // table of same
305   static oop _mirrors[T_VOID+1];
306 
307   static oop java_mirror(BasicType t) {
308     assert((uint)t < T_VOID+1, "range check");
309     return check_mirror(_mirrors[t]);
310   }
311   static oop      main_thread_group()                 { return _main_thread_group; }
312   static void set_main_thread_group(oop group)        { _main_thread_group = group;}
313 
314   static oop      system_thread_group()               { return _system_thread_group; }
315   static void set_system_thread_group(oop group)      { _system_thread_group = group;}
316 
317   static objArrayOop  the_empty_class_klass_array ()  { return _the_empty_class_klass_array;   }
318   static Array<Klass*>* the_array_interfaces_array() { return _the_array_interfaces_array;   }
319   static oop          the_null_string()               { return _the_null_string;               }
320   static oop          the_min_jint_string()          { return _the_min_jint_string;          }
321 
322   static Method*      finalizer_register_method()     { return _finalizer_register_cache->get_method(); }
323   static Method*      loader_addClass_method()        { return _loader_addClass_cache->get_method(); }
324 
325   static Method*      protection_domain_implies_method() { return _pd_implies_cache->get_method(); }
326   static Method*      throw_illegal_access_error()    { return _throw_illegal_access_error_cache->get_method(); }
327 
328   static Method*      do_stack_walk_method()          { return _do_stack_walk_cache->get_method(); }
329 
330   static oop          the_null_sentinel()             { return _the_null_sentinel;             }
331   static address      the_null_sentinel_addr()        { return (address) &_the_null_sentinel;  }
332 
333   // Function to initialize these
334   static void initialize_known_methods(TRAPS);
335 
336   static oop          null_ptr_exception_instance()   { return _null_ptr_exception_instance;   }
337   static oop          arithmetic_exception_instance() { return _arithmetic_exception_instance; }
338   static oop          virtual_machine_error_instance() { return _virtual_machine_error_instance; }
339   static oop          vm_exception()                  { return _vm_exception; }
340 
341   // Reference pending list manipulation.  Access is protected by
342   // Heap_lock.  The getter, setter and predicate require the caller
343   // owns the lock.  Swap is used by parallel non-concurrent reference
344   // processing threads, where some higher level controller owns
345   // Heap_lock, so requires the lock is locked, but not necessarily by
346   // the current thread.
347   static oop          reference_pending_list();
348   static void         set_reference_pending_list(oop list);
349   static bool         has_reference_pending_list();
350   static oop          swap_reference_pending_list(oop list);
351 
352   static Array<int>*             the_empty_int_array()    { return _the_empty_int_array; }
353   static Array<u2>*              the_empty_short_array()  { return _the_empty_short_array; }
354   static Array<Method*>*         the_empty_method_array() { return _the_empty_method_array; }
355   static Array<Klass*>*          the_empty_klass_array()  { return _the_empty_klass_array; }
356   static Array<InstanceKlass*>*  the_empty_instance_klass_array() { return _the_empty_instance_klass_array; }
357 
358   // OutOfMemoryError support. Returns an error with the required message. The returned error
359   // may or may not have a backtrace. If error has a backtrace then the stack trace is already
360   // filled in.
361   static oop out_of_memory_error_java_heap()          { return gen_out_of_memory_error(_out_of_memory_error_java_heap);  }
362   static oop out_of_memory_error_metaspace()          { return gen_out_of_memory_error(_out_of_memory_error_metaspace);   }
363   static oop out_of_memory_error_class_metaspace()    { return gen_out_of_memory_error(_out_of_memory_error_class_metaspace);   }
364   static oop out_of_memory_error_array_size()         { return gen_out_of_memory_error(_out_of_memory_error_array_size); }
365   static oop out_of_memory_error_gc_overhead_limit()  { return gen_out_of_memory_error(_out_of_memory_error_gc_overhead_limit);  }
366   static oop out_of_memory_error_realloc_objects()    { return gen_out_of_memory_error(_out_of_memory_error_realloc_objects);  }
367   // Throw default _out_of_memory_error_retry object as it will never propagate out of the VM
368   static oop out_of_memory_error_retry()              { return _out_of_memory_error_retry;  }
369   static oop delayed_stack_overflow_error_message()   { return _delayed_stack_overflow_error_message; }
370 
371   // The particular choice of collected heap.
372   static CollectedHeap* heap() { return _collectedHeap; }
373 
374   // For UseCompressedOops
375   // Narrow Oop encoding mode:
376   // 0 - Use 32-bits oops without encoding when
377   //     NarrowOopHeapBaseMin + heap_size < 4Gb
378   // 1 - Use zero based compressed oops with encoding when
379   //     NarrowOopHeapBaseMin + heap_size < 32Gb
380   // 2 - Use compressed oops with disjoint heap base if
381   //     base is 32G-aligned and base > 0. This allows certain
382   //     optimizations in encoding/decoding.
383   //     Disjoint: Bits used in base are disjoint from bits used
384   //     for oops ==> oop = (cOop << 3) | base.  One can disjoint
385   //     the bits of an oop into base and compressed oop.
386   // 3 - Use compressed oops with heap base + encoding.
387   enum NARROW_OOP_MODE {
388     UnscaledNarrowOop  = 0,
389     ZeroBasedNarrowOop = 1,
390     DisjointBaseNarrowOop = 2,
391     HeapBasedNarrowOop = 3,
392     AnyNarrowOopMode = 4
393   };
394   static NARROW_OOP_MODE narrow_oop_mode();
395   static const char* narrow_oop_mode_to_string(NARROW_OOP_MODE mode);
396   static char*    preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode);
397   static char*    preferred_metaspace_base(size_t heap_size, NARROW_OOP_MODE mode);
398   static address  narrow_oop_base()                  { return  _narrow_oop._base; }
399   // Test whether bits of addr and possible offsets into the heap overlap.
400   static bool     is_disjoint_heap_base_address(address addr) {
401     return (((uint64_t)(intptr_t)addr) &
402             (((uint64_t)UCONST64(0xFFFFffffFFFFffff)) >> (32-LogMinObjAlignmentInBytes))) == 0;
403   }
404   // Check for disjoint base compressed oops.
405   static bool     narrow_oop_base_disjoint()        {
406     return _narrow_oop._base != NULL && is_disjoint_heap_base_address(_narrow_oop._base);
407   }
408   // Check for real heapbased compressed oops.
409   // We must subtract the base as the bits overlap.
410   // If we negate above function, we also get unscaled and zerobased.
411   static bool     narrow_oop_base_overlaps()          {
412     return _narrow_oop._base != NULL && !is_disjoint_heap_base_address(_narrow_oop._base);
413   }
414   static bool  is_narrow_oop_base(void* addr)             { return (narrow_oop_base() == (address)addr); }
415   static int      narrow_oop_shift()                      { return  _narrow_oop._shift; }
416   static bool     narrow_oop_use_implicit_null_checks()   { return  _narrow_oop._use_implicit_null_checks; }
417 
418   // For UseCompressedClassPointers
419   static address  narrow_klass_base()                     { return  _narrow_klass._base; }
420   static bool  is_narrow_klass_base(void* addr)           { return (narrow_klass_base() == (address)addr); }
421   static uint64_t narrow_klass_range()                    { return  _narrow_klass_range; }
422   static int      narrow_klass_shift()                    { return  _narrow_klass._shift; }
423   static bool     narrow_klass_use_implicit_null_checks() { return  _narrow_klass._use_implicit_null_checks; }
424 
425   static address* narrow_ptrs_base_addr()                 { return &_narrow_ptrs_base; }
426   static void     set_narrow_ptrs_base(address a)         { _narrow_ptrs_base = a; }
427   static address  narrow_ptrs_base()                      { return _narrow_ptrs_base; }
428 
429   static void     print_compressed_oops_mode(outputStream* st);
430 
431   // this is set in vm_version on sparc (and then reset in universe afaict)
432   static void     set_narrow_oop_shift(int shift)         {
433     _narrow_oop._shift   = shift;
434   }
435 
436   static void     set_narrow_klass_shift(int shift)       {
437     assert(shift == 0 || shift == LogKlassAlignmentInBytes, "invalid shift for klass ptrs");
438     _narrow_klass._shift   = shift;
439   }
440 
441   // Reserve Java heap and determine CompressedOops mode
442   static ReservedSpace reserve_heap(size_t heap_size, size_t alignment);
443 
444   // Historic gc information
445   static size_t get_heap_capacity_at_last_gc()         { return _heap_capacity_at_last_gc; }
446   static size_t get_heap_free_at_last_gc()             { return _heap_capacity_at_last_gc - _heap_used_at_last_gc; }
447   static size_t get_heap_used_at_last_gc()             { return _heap_used_at_last_gc; }
448   static void update_heap_info_at_gc();
449 
450   // Testers
451   static bool is_bootstrapping()                      { return _bootstrapping; }
452   static bool is_module_initialized()                 { return _module_initialized; }
453   static bool is_fully_initialized()                  { return _fully_initialized; }
454 
455   static bool        on_page_boundary(void* addr);
456   static bool        should_fill_in_stack_trace(Handle throwable);
457   static void check_alignment(uintx size, uintx alignment, const char* name);
458 
459   // Iteration
460 
461   // Apply "f" to the addresses of all the direct heap pointers maintained
462   // as static fields of "Universe".
463   static void oops_do(OopClosure* f);
464 
465   // CDS support
466   static void serialize(SerializeClosure* f);
467 
468   // Apply "f" to all klasses for basic types (classes not present in
469   // SystemDictionary).
470   static void basic_type_classes_do(void f(Klass*));
471   static void basic_type_classes_do(KlassClosure* closure);
472   static void metaspace_pointers_do(MetaspaceClosure* it);
473 
474   // Debugging
475   enum VERIFY_FLAGS {
476     Verify_Threads = 1,
477     Verify_Heap = 2,
478     Verify_SymbolTable = 4,
479     Verify_StringTable = 8,
480     Verify_CodeCache = 16,
481     Verify_SystemDictionary = 32,
482     Verify_ClassLoaderDataGraph = 64,
483     Verify_MetaspaceUtils = 128,
484     Verify_JNIHandles = 256,
485     Verify_CodeCacheOops = 512,
486     Verify_All = -1
487   };
488   static void initialize_verify_flags();
489   static bool should_verify_subset(uint subset);
490   static void disable_verify_subset(uint subset) { verify_flags &= ~subset; }
491   static bool verify_in_progress() { return _verify_in_progress; }
492   static void verify(VerifyOption option, const char* prefix);
493   static void verify(const char* prefix) {
494     verify(VerifyOption_Default, prefix);
495   }
496   static void verify() {
497     verify("");
498   }
499 
500   static int  verify_count()       { return _verify_count; }
501   static void print_on(outputStream* st);
502   static void print_heap_at_SIGBREAK();
503   static void print_heap_before_gc();
504   static void print_heap_after_gc();
505 
506   // Change the number of dummy objects kept reachable by the full gc dummy
507   // array; this should trigger relocation in a sliding compaction collector.
508   debug_only(static bool release_fullgc_alot_dummy();)
509   // The non-oop pattern (see compiledIC.hpp, etc)
510   static void*   non_oop_word();
511 
512   // Oop verification (see MacroAssembler::verify_oop)
513   static uintptr_t verify_oop_mask()          PRODUCT_RETURN0;
514   static uintptr_t verify_oop_bits()          PRODUCT_RETURN0;
515   static uintptr_t verify_mark_bits()         PRODUCT_RETURN0;
516   static uintptr_t verify_mark_mask()         PRODUCT_RETURN0;
517 
518   // Compiler support
519   static int base_vtable_size()               { return _base_vtable_size; }
520 };
521 
522 class DeferredObjAllocEvent : public CHeapObj<mtInternal> {
523   private:
524     oop    _oop;
525     size_t _bytesize;
526     jint   _arena_id;
527 
528   public:
529     DeferredObjAllocEvent(const oop o, const size_t s, const jint id) {
530       _oop      = o;
531       _bytesize = s;
532       _arena_id = id;
533     }
534 
535     ~DeferredObjAllocEvent() {
536     }
537 
538     jint   arena_id() { return _arena_id; }
539     size_t bytesize() { return _bytesize; }
540     oop    get_oop()  { return _oop; }
541 };
542 
543 #endif // SHARE_VM_MEMORY_UNIVERSE_HPP