1 /*
   2  * Copyright (c) 1997, 2019, 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_MEMORY_ALLOCATION_HPP
  26 #define SHARE_MEMORY_ALLOCATION_HPP
  27 
  28 #include "utilities/globalDefinitions.hpp"
  29 #include "utilities/macros.hpp"
  30 
  31 #include <new>
  32 
  33 class outputStream;
  34 class Thread;
  35 
  36 class AllocFailStrategy {
  37 public:
  38   enum AllocFailEnum { EXIT_OOM, RETURN_NULL };
  39 };
  40 typedef AllocFailStrategy::AllocFailEnum AllocFailType;
  41 
  42 // The virtual machine must never call one of the implicitly declared
  43 // global allocation or deletion functions.  (Such calls may result in
  44 // link-time or run-time errors.)  For convenience and documentation of
  45 // intended use, classes in the virtual machine may be derived from one
  46 // of the following allocation classes, some of which define allocation
  47 // and deletion functions.
  48 // Note: std::malloc and std::free should never called directly.
  49 
  50 //
  51 // For objects allocated in the resource area (see resourceArea.hpp).
  52 // - ResourceObj
  53 //
  54 // For objects allocated in the C-heap (managed by: free & malloc and tracked with NMT)
  55 // - CHeapObj
  56 //
  57 // For objects allocated on the stack.
  58 // - StackObj
  59 //
  60 // For classes used as name spaces.
  61 // - AllStatic
  62 //
  63 // For classes in Metaspace (class data)
  64 // - MetaspaceObj
  65 //
  66 // The printable subclasses are used for debugging and define virtual
  67 // member functions for printing. Classes that avoid allocating the
  68 // vtbl entries in the objects should therefore not be the printable
  69 // subclasses.
  70 //
  71 // The following macros and function should be used to allocate memory
  72 // directly in the resource area or in the C-heap, The _OBJ variants
  73 // of the NEW/FREE_C_HEAP macros are used for alloc/dealloc simple
  74 // objects which are not inherited from CHeapObj, note constructor and
  75 // destructor are not called. The preferable way to allocate objects
  76 // is using the new operator.
  77 //
  78 // WARNING: The array variant must only be used for a homogenous array
  79 // where all objects are of the exact type specified. If subtypes are
  80 // stored in the array then must pay attention to calling destructors
  81 // at needed.
  82 //
  83 // NEW_RESOURCE_ARRAY*
  84 // REALLOC_RESOURCE_ARRAY*
  85 // FREE_RESOURCE_ARRAY*
  86 // NEW_RESOURCE_OBJ*
  87 // NEW_C_HEAP_ARRAY*
  88 // REALLOC_C_HEAP_ARRAY*
  89 // FREE_C_HEAP_ARRAY*
  90 // NEW_C_HEAP_OBJ*
  91 // FREE_C_HEAP_OBJ
  92 //
  93 // char* AllocateHeap(size_t size, MEMFLAGS flags, const NativeCallStack& stack, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  94 // char* AllocateHeap(size_t size, MEMFLAGS flags, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  95 // char* ReallocateHeap(char *old, size_t size, MEMFLAGS flag, AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
  96 // void FreeHeap(void* p);
  97 //
  98 // In non product mode we introduce a super class for all allocation classes
  99 // that supports printing.
 100 // We avoid the superclass in product mode to save space.
 101 
 102 #ifdef PRODUCT
 103 #define ALLOCATION_SUPER_CLASS_SPEC
 104 #else
 105 #define ALLOCATION_SUPER_CLASS_SPEC : public AllocatedObj
 106 class AllocatedObj {
 107  public:
 108   // Printing support
 109   void print() const;
 110   void print_value() const;
 111 
 112   virtual void print_on(outputStream* st) const;
 113   virtual void print_value_on(outputStream* st) const;
 114 };
 115 #endif
 116 
 117 #define MEMORY_TYPES_DO(f) \
 118   /* Memory type by sub systems. It occupies lower byte. */  \
 119   f(mtJavaHeap,      "Java Heap")   /* Java heap                                 */ \
 120   f(mtClass,         "Class")       /* Java classes                              */ \
 121   f(mtThread,        "Thread")      /* thread objects                            */ \
 122   f(mtThreadStack,   "Thread Stack")                                                \
 123   f(mtCode,          "Code")        /* generated code                            */ \
 124   f(mtGC,            "GC")                                                          \
 125   f(mtCompiler,      "Compiler")                                                    \
 126   f(mtJVMCI,         "JVMCI")                                                       \
 127   f(mtInternal,      "Internal")    /* memory used by VM, but does not belong to */ \
 128                                     /* any of above categories, and not used by  */ \
 129                                     /* NMT                                       */ \
 130   f(mtOther,         "Other")       /* memory not used by VM                     */ \
 131   f(mtSymbol,        "Symbol")                                                      \
 132   f(mtNMT,           "Native Memory Tracking")  /* memory used by NMT            */ \
 133   f(mtClassShared,   "Shared class space")      /* class data sharing            */ \
 134   f(mtChunk,         "Arena Chunk") /* chunk that holds content of arenas        */ \
 135   f(mtTest,          "Test")        /* Test type for verifying NMT               */ \
 136   f(mtTracing,       "Tracing")                                                     \
 137   f(mtLogging,       "Logging")                                                     \
 138   f(mtStatistics,    "Statistics")                                                  \
 139   f(mtArguments,     "Arguments")                                                   \
 140   f(mtModule,        "Module")                                                      \
 141   f(mtSafepoint,     "Safepoint")                                                   \
 142   f(mtSynchronizer,  "Synchronization")                                             \
 143   f(mtNone,          "Unknown")                                                     \
 144   //end
 145 
 146 #define MEMORY_TYPE_DECLARE_ENUM(type, human_readable) \
 147   type,
 148 
 149 /*
 150  * Memory types
 151  */
 152 enum MemoryType {
 153   MEMORY_TYPES_DO(MEMORY_TYPE_DECLARE_ENUM)
 154   mt_number_of_types   // number of memory types (mtDontTrack
 155                        // is not included as validate type)
 156 };
 157 
 158 typedef MemoryType MEMFLAGS;
 159 
 160 
 161 #if INCLUDE_NMT
 162 
 163 extern bool NMT_track_callsite;
 164 
 165 #else
 166 
 167 const bool NMT_track_callsite = false;
 168 
 169 #endif // INCLUDE_NMT
 170 
 171 class NativeCallStack;
 172 
 173 
 174 char* AllocateHeap(size_t size,
 175                    MEMFLAGS flags,
 176                    const NativeCallStack& stack,
 177                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 178 char* AllocateHeap(size_t size,
 179                    MEMFLAGS flags,
 180                    AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 181 
 182 char* ReallocateHeap(char *old,
 183                      size_t size,
 184                      MEMFLAGS flag,
 185                      AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 186 
 187 // handles NULL pointers
 188 void FreeHeap(void* p);
 189 
 190 template <MEMFLAGS F> class CHeapObj ALLOCATION_SUPER_CLASS_SPEC {
 191  public:
 192   ALWAYSINLINE void* operator new(size_t size) throw() {
 193     return (void*)AllocateHeap(size, F);
 194   }
 195 
 196   ALWAYSINLINE void* operator new(size_t size,
 197                                   const NativeCallStack& stack) throw() {
 198     return (void*)AllocateHeap(size, F, stack);
 199   }
 200 
 201   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&,
 202                                   const NativeCallStack& stack) throw() {
 203     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 204   }
 205 
 206   ALWAYSINLINE void* operator new(size_t size, const std::nothrow_t&) throw() {
 207     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 208   }
 209 
 210   ALWAYSINLINE void* operator new[](size_t size) throw() {
 211     return (void*)AllocateHeap(size, F);
 212   }
 213 
 214   ALWAYSINLINE void* operator new[](size_t size,
 215                                   const NativeCallStack& stack) throw() {
 216     return (void*)AllocateHeap(size, F, stack);
 217   }
 218 
 219   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&,
 220                                     const NativeCallStack& stack) throw() {
 221     return (void*)AllocateHeap(size, F, stack, AllocFailStrategy::RETURN_NULL);
 222   }
 223 
 224   ALWAYSINLINE void* operator new[](size_t size, const std::nothrow_t&) throw() {
 225     return (void*)AllocateHeap(size, F, AllocFailStrategy::RETURN_NULL);
 226   }
 227 
 228   void  operator delete(void* p)     { FreeHeap(p); }
 229   void  operator delete [] (void* p) { FreeHeap(p); }
 230 };
 231 
 232 // Base class for objects allocated on the stack only.
 233 // Calling new or delete will result in fatal error.
 234 
 235 class StackObj ALLOCATION_SUPER_CLASS_SPEC {
 236  private:
 237   void* operator new(size_t size) throw();
 238   void* operator new [](size_t size) throw();
 239   void  operator delete(void* p);
 240   void  operator delete [](void* p);
 241 };
 242 
 243 // Base class for objects stored in Metaspace.
 244 // Calling delete will result in fatal error.
 245 //
 246 // Do not inherit from something with a vptr because this class does
 247 // not introduce one.  This class is used to allocate both shared read-only
 248 // and shared read-write classes.
 249 //
 250 
 251 class ClassLoaderData;
 252 class MetaspaceClosure;
 253 
 254 class MetaspaceObj {
 255   friend class VMStructs;
 256   // When CDS is enabled, all shared metaspace objects are mapped
 257   // into a single contiguous memory block, so we can use these
 258   // two pointers to quickly determine if something is in the
 259   // shared metaspace.
 260   // When CDS is not enabled, both pointers are set to NULL.
 261   static void* _shared_metaspace_base;  // (inclusive) low address
 262   static void* _shared_metaspace_top;   // (exclusive) high address
 263 
 264  public:
 265 
 266   // Returns true if the pointer points to a valid MetaspaceObj. A valid
 267   // MetaspaceObj is MetaWord-aligned and contained within either
 268   // non-shared or shared metaspace.
 269   static bool is_valid(const MetaspaceObj* p);
 270 
 271   static bool is_shared(const MetaspaceObj* p) {
 272     // If no shared metaspace regions are mapped, _shared_metaspace_{base,top} will
 273     // both be NULL and all values of p will be rejected quickly.
 274     return (((void*)p) < _shared_metaspace_top &&
 275             ((void*)p) >= _shared_metaspace_base);
 276   }
 277   bool is_shared() const { return MetaspaceObj::is_shared(this); }
 278 
 279   void print_address_on(outputStream* st) const;  // nonvirtual address printing
 280 
 281   static void set_shared_metaspace_range(void* base, void* top) {
 282     _shared_metaspace_base = base;
 283     _shared_metaspace_top = top;
 284   }
 285 
 286   static void expand_shared_metaspace_range(void* top) {
 287     assert(top >= _shared_metaspace_top, "must be");
 288     _shared_metaspace_top = top;
 289   }
 290 
 291   static void* shared_metaspace_base() { return _shared_metaspace_base; }
 292   static void* shared_metaspace_top()  { return _shared_metaspace_top;  }
 293 
 294 #define METASPACE_OBJ_TYPES_DO(f) \
 295   f(Class) \
 296   f(Symbol) \
 297   f(TypeArrayU1) \
 298   f(TypeArrayU2) \
 299   f(TypeArrayU4) \
 300   f(TypeArrayU8) \
 301   f(TypeArrayOther) \
 302   f(Method) \
 303   f(ConstMethod) \
 304   f(MethodData) \
 305   f(ConstantPool) \
 306   f(ConstantPoolCache) \
 307   f(Annotations) \
 308   f(MethodCounters)
 309 
 310 #define METASPACE_OBJ_TYPE_DECLARE(name) name ## Type,
 311 #define METASPACE_OBJ_TYPE_NAME_CASE(name) case name ## Type: return #name;
 312 
 313   enum Type {
 314     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
 315     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
 316     _number_of_types
 317   };
 318 
 319   static const char * type_name(Type type) {
 320     switch(type) {
 321     METASPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
 322     default:
 323       ShouldNotReachHere();
 324       return NULL;
 325     }
 326   }
 327 
 328   static MetaspaceObj::Type array_type(size_t elem_size) {
 329     switch (elem_size) {
 330     case 1: return TypeArrayU1Type;
 331     case 2: return TypeArrayU2Type;
 332     case 4: return TypeArrayU4Type;
 333     case 8: return TypeArrayU8Type;
 334     default:
 335       return TypeArrayOtherType;
 336     }
 337   }
 338 
 339   void* operator new(size_t size, ClassLoaderData* loader_data,
 340                      size_t word_size,
 341                      Type type, Thread* thread) throw();
 342                      // can't use TRAPS from this header file.
 343   void operator delete(void* p) { ShouldNotCallThis(); }
 344 
 345   // Declare a *static* method with the same signature in any subclass of MetaspaceObj
 346   // that should be read-only by default. See symbol.hpp for an example. This function
 347   // is used by the templates in metaspaceClosure.hpp
 348   static bool is_read_only_by_default() { return false; }
 349 };
 350 
 351 // Base class for classes that constitute name spaces.
 352 
 353 class Arena;
 354 
 355 class AllStatic {
 356  public:
 357   AllStatic()  { ShouldNotCallThis(); }
 358   ~AllStatic() { ShouldNotCallThis(); }
 359 };
 360 
 361 
 362 extern char* resource_allocate_bytes(size_t size,
 363     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 364 extern char* resource_allocate_bytes(Thread* thread, size_t size,
 365     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 366 extern char* resource_reallocate_bytes( char *old, size_t old_size, size_t new_size,
 367     AllocFailType alloc_failmode = AllocFailStrategy::EXIT_OOM);
 368 extern void resource_free_bytes( char *old, size_t size );
 369 
 370 //----------------------------------------------------------------------
 371 // Base class for objects allocated in the resource area per default.
 372 // Optionally, objects may be allocated on the C heap with
 373 // new(ResourceObj::C_HEAP) Foo(...) or in an Arena with new (&arena)
 374 // ResourceObj's can be allocated within other objects, but don't use
 375 // new or delete (allocation_type is unknown).  If new is used to allocate,
 376 // use delete to deallocate.
 377 class ResourceObj ALLOCATION_SUPER_CLASS_SPEC {
 378  public:
 379   enum allocation_type { STACK_OR_EMBEDDED = 0, RESOURCE_AREA, C_HEAP, ARENA, allocation_mask = 0x3 };
 380   static void set_allocation_type(address res, allocation_type type) NOT_DEBUG_RETURN;
 381 #ifdef ASSERT
 382  private:
 383   // When this object is allocated on stack the new() operator is not
 384   // called but garbage on stack may look like a valid allocation_type.
 385   // Store negated 'this' pointer when new() is called to distinguish cases.
 386   // Use second array's element for verification value to distinguish garbage.
 387   uintptr_t _allocation_t[2];
 388   bool is_type_set() const;
 389   void initialize_allocation_info();
 390  public:
 391   allocation_type get_allocation_type() const;
 392   bool allocated_on_stack()    const { return get_allocation_type() == STACK_OR_EMBEDDED; }
 393   bool allocated_on_res_area() const { return get_allocation_type() == RESOURCE_AREA; }
 394   bool allocated_on_C_heap()   const { return get_allocation_type() == C_HEAP; }
 395   bool allocated_on_arena()    const { return get_allocation_type() == ARENA; }
 396 protected:
 397   ResourceObj(); // default constructor
 398   ResourceObj(const ResourceObj& r); // default copy constructor
 399   ResourceObj& operator=(const ResourceObj& r); // default copy assignment
 400   ~ResourceObj();
 401 #endif // ASSERT
 402 
 403  public:
 404   void* operator new(size_t size, allocation_type type, MEMFLAGS flags) throw();
 405   void* operator new [](size_t size, allocation_type type, MEMFLAGS flags) throw();
 406   void* operator new(size_t size, const std::nothrow_t&  nothrow_constant,
 407       allocation_type type, MEMFLAGS flags) throw();
 408   void* operator new [](size_t size, const std::nothrow_t&  nothrow_constant,
 409       allocation_type type, MEMFLAGS flags) throw();
 410 
 411   void* operator new(size_t size, Arena *arena) throw();
 412 
 413   void* operator new [](size_t size, Arena *arena) throw();
 414 
 415   void* operator new(size_t size) throw() {
 416       address res = (address)resource_allocate_bytes(size);
 417       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 418       return res;
 419   }
 420 
 421   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
 422       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 423       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 424       return res;
 425   }
 426 
 427   void* operator new [](size_t size) throw() {
 428       address res = (address)resource_allocate_bytes(size);
 429       DEBUG_ONLY(set_allocation_type(res, RESOURCE_AREA);)
 430       return res;
 431   }
 432 
 433   void* operator new [](size_t size, const std::nothrow_t& nothrow_constant) throw() {
 434       address res = (address)resource_allocate_bytes(size, AllocFailStrategy::RETURN_NULL);
 435       DEBUG_ONLY(if (res != NULL) set_allocation_type(res, RESOURCE_AREA);)
 436       return res;
 437   }
 438 
 439   void  operator delete(void* p);
 440   void  operator delete [](void* p);
 441 };
 442 
 443 // One of the following macros must be used when allocating an array
 444 // or object to determine whether it should reside in the C heap on in
 445 // the resource area.
 446 
 447 #define NEW_RESOURCE_ARRAY(type, size)\
 448   (type*) resource_allocate_bytes((size) * sizeof(type))
 449 
 450 #define NEW_RESOURCE_ARRAY_RETURN_NULL(type, size)\
 451   (type*) resource_allocate_bytes((size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 452 
 453 #define NEW_RESOURCE_ARRAY_IN_THREAD(thread, type, size)\
 454   (type*) resource_allocate_bytes(thread, (size) * sizeof(type))
 455 
 456 #define NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(thread, type, size)\
 457   (type*) resource_allocate_bytes(thread, (size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 458 
 459 #define REALLOC_RESOURCE_ARRAY(type, old, old_size, new_size)\
 460   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type), (new_size) * sizeof(type))
 461 
 462 #define REALLOC_RESOURCE_ARRAY_RETURN_NULL(type, old, old_size, new_size)\
 463   (type*) resource_reallocate_bytes((char*)(old), (old_size) * sizeof(type),\
 464                                     (new_size) * sizeof(type), AllocFailStrategy::RETURN_NULL)
 465 
 466 #define FREE_RESOURCE_ARRAY(type, old, size)\
 467   resource_free_bytes((char*)(old), (size) * sizeof(type))
 468 
 469 #define FREE_FAST(old)\
 470     /* nop */
 471 
 472 #define NEW_RESOURCE_OBJ(type)\
 473   NEW_RESOURCE_ARRAY(type, 1)
 474 
 475 #define NEW_RESOURCE_OBJ_RETURN_NULL(type)\
 476   NEW_RESOURCE_ARRAY_RETURN_NULL(type, 1)
 477 
 478 #define NEW_C_HEAP_ARRAY3(type, size, memflags, pc, allocfail)\
 479   (type*) AllocateHeap((size) * sizeof(type), memflags, pc, allocfail)
 480 
 481 #define NEW_C_HEAP_ARRAY2(type, size, memflags, pc)\
 482   (type*) (AllocateHeap((size) * sizeof(type), memflags, pc))
 483 
 484 #define NEW_C_HEAP_ARRAY(type, size, memflags)\
 485   (type*) (AllocateHeap((size) * sizeof(type), memflags))
 486 
 487 #define NEW_C_HEAP_ARRAY2_RETURN_NULL(type, size, memflags, pc)\
 488   NEW_C_HEAP_ARRAY3(type, (size), memflags, pc, AllocFailStrategy::RETURN_NULL)
 489 
 490 #define NEW_C_HEAP_ARRAY_RETURN_NULL(type, size, memflags)\
 491   NEW_C_HEAP_ARRAY3(type, (size), memflags, CURRENT_PC, AllocFailStrategy::RETURN_NULL)
 492 
 493 #define REALLOC_C_HEAP_ARRAY(type, old, size, memflags)\
 494   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags))
 495 
 496 #define REALLOC_C_HEAP_ARRAY_RETURN_NULL(type, old, size, memflags)\
 497   (type*) (ReallocateHeap((char*)(old), (size) * sizeof(type), memflags, AllocFailStrategy::RETURN_NULL))
 498 
 499 #define FREE_C_HEAP_ARRAY(type, old) \
 500   FreeHeap((char*)(old))
 501 
 502 // allocate type in heap without calling ctor
 503 #define NEW_C_HEAP_OBJ(type, memflags)\
 504   NEW_C_HEAP_ARRAY(type, 1, memflags)
 505 
 506 #define NEW_C_HEAP_OBJ_RETURN_NULL(type, memflags)\
 507   NEW_C_HEAP_ARRAY_RETURN_NULL(type, 1, memflags)
 508 
 509 // deallocate obj of type in heap without calling dtor
 510 #define FREE_C_HEAP_OBJ(objname)\
 511   FreeHeap((char*)objname);
 512 
 513 
 514 //------------------------------ReallocMark---------------------------------
 515 // Code which uses REALLOC_RESOURCE_ARRAY should check an associated
 516 // ReallocMark, which is declared in the same scope as the reallocated
 517 // pointer.  Any operation that could __potentially__ cause a reallocation
 518 // should check the ReallocMark.
 519 class ReallocMark: public StackObj {
 520 protected:
 521   NOT_PRODUCT(int _nesting;)
 522 
 523 public:
 524   ReallocMark()   PRODUCT_RETURN;
 525   void check()    PRODUCT_RETURN;
 526 };
 527 
 528 // Helper class to allocate arrays that may become large.
 529 // Uses the OS malloc for allocations smaller than ArrayAllocatorMallocLimit
 530 // and uses mapped memory for larger allocations.
 531 // Most OS mallocs do something similar but Solaris malloc does not revert
 532 // to mapped memory for large allocations. By default ArrayAllocatorMallocLimit
 533 // is set so that we always use malloc except for Solaris where we set the
 534 // limit to get mapped memory.
 535 template <class E>
 536 class ArrayAllocator : public AllStatic {
 537  private:
 538   static bool should_use_malloc(size_t length);
 539 
 540   static E* allocate_malloc(size_t length, MEMFLAGS flags);
 541   static E* allocate_mmap(size_t length, MEMFLAGS flags);
 542 
 543   static void free_malloc(E* addr, size_t length);
 544   static void free_mmap(E* addr, size_t length);
 545 
 546  public:
 547   static E* allocate(size_t length, MEMFLAGS flags);
 548   static E* reallocate(E* old_addr, size_t old_length, size_t new_length, MEMFLAGS flags);
 549   static void free(E* addr, size_t length);
 550 };
 551 
 552 // Uses mmaped memory for all allocations. All allocations are initially
 553 // zero-filled. No pre-touching.
 554 template <class E>
 555 class MmapArrayAllocator : public AllStatic {
 556  private:
 557   static size_t size_for(size_t length);
 558 
 559  public:
 560   static E* allocate_or_null(size_t length, MEMFLAGS flags);
 561   static E* allocate(size_t length, MEMFLAGS flags);
 562   static void free(E* addr, size_t length);
 563 };
 564 
 565 // Uses malloc:ed memory for all allocations.
 566 template <class E>
 567 class MallocArrayAllocator : public AllStatic {
 568  public:
 569   static size_t size_for(size_t length);
 570 
 571   static E* allocate(size_t length, MEMFLAGS flags);
 572   static void free(E* addr);
 573 };
 574 
 575 #endif // SHARE_MEMORY_ALLOCATION_HPP