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 /*

  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.

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

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * 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.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "memory/allocation.hpp"

 #include "memory/allocation.inline.hpp"

 #include "memory/genCollectedHeap.hpp"

 #include "memory/metaspaceShared.hpp"

 #include "memory/resourceArea.hpp"

 #include "memory/universe.hpp"

 #include "runtime/atomic.hpp"

 #include "runtime/os.hpp"

 #include "runtime/task.hpp"

 #include "runtime/threadCritical.hpp"

 #include "services/memTracker.hpp"

 #include "utilities/ostream.hpp"

 #ifdef TARGET_OS_FAMILY_linux

 # include "os_linux.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_solaris

 # include "os_solaris.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_windows

 # include "os_windows.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_bsd

 # include "os_bsd.inline.hpp"

 #endif

 void* StackObj::operator new(size_t size)  { ShouldNotCallThis(); return 0; };

 void  StackObj::operator delete(void* p)   { ShouldNotCallThis(); };

 void* StackObj::operator new [](size_t size)  { ShouldNotCallThis(); return 0; };

 void  StackObj::operator delete [](void* p)   { ShouldNotCallThis(); };

 void* _ValueObj::operator new(size_t size)  { ShouldNotCallThis(); return 0; };

 void  _ValueObj::operator delete(void* p)   { ShouldNotCallThis(); };

 void* _ValueObj::operator new [](size_t size)  { ShouldNotCallThis(); return 0; };

 void  _ValueObj::operator delete [](void* p)   { ShouldNotCallThis(); };

 void* MetaspaceObj::operator new(size_t size, ClassLoaderData* loader_data,

                                 size_t word_size, bool read_only, TRAPS) {

   // Klass has it's own operator new

   return Metaspace::allocate(loader_data, word_size, read_only,

                              Metaspace::NonClassType, CHECK_NULL);

 }

 bool MetaspaceObj::is_shared() const {

   return MetaspaceShared::is_in_shared_space(this);

 }

 bool MetaspaceObj::is_metadata() const {

   // GC Verify checks use this in guarantees.

   // TODO: either replace them with is_metaspace_object() or remove them.

   // is_metaspace_object() is slower than this test.  This test doesn't

   // seem very useful for metaspace objects anymore though.

   return !Universe::heap()->is_in_reserved(this);

 }

 bool MetaspaceObj::is_metaspace_object() const {

   return Metaspace::contains((void*)this);

 }

 void MetaspaceObj::print_address_on(outputStream* st) const {

   st->print(" {"INTPTR_FORMAT"}", this);

 }

 void* ResourceObj::operator new(size_t size, allocation_type type, MEMFLAGS flags) {

   address res;

   switch (type) {

    case C_HEAP:

     res = (address)AllocateHeap(size, flags, CALLER_PC);

     DEBUG_ONLY(set_allocation_type(res, C_HEAP);)

     break;

    case RESOURCE_AREA:

     // new(size) sets allocation type RESOURCE_AREA.

     res = (address)operator new(size);

     break;

    default:

     ShouldNotReachHere();

   }

   return res;

 }

 void* ResourceObj::operator new [](size_t size, allocation_type type, MEMFLAGS flags) {

   return (address) operator new(size, type, flags);

 }

 void* ResourceObj::operator new(size_t size, const std::nothrow_t&  nothrow_constant,

     allocation_type type, MEMFLAGS flags) {

   //should only call this with std::nothrow, use other operator new() otherwise

   address res;

   switch (type) {

    case C_HEAP:

     res = (address)AllocateHeap(size, flags, CALLER_PC, AllocFailStrategy::RETURN_NULL);

     DEBUG_ONLY(if (res!= NULL) set_allocation_type(res, C_HEAP);)

     break;

    case RESOURCE_AREA:

     // new(size) sets allocation type RESOURCE_AREA.

     res = (address)operator new(size, std::nothrow);

     break;

    default:

     ShouldNotReachHere();

   }

   return res;

 }

 void* ResourceObj::operator new [](size_t size, const std::nothrow_t&  nothrow_constant,

     allocation_type type, MEMFLAGS flags) {

   return (address)operator new(size, nothrow_constant, type, flags);

 }

 void ResourceObj::operator delete(void* p) {

   assert(((ResourceObj *)p)->allocated_on_C_heap(),

          "delete only allowed for C_HEAP objects");

   DEBUG_ONLY(((ResourceObj *)p)->_allocation_t[0] = (uintptr_t)badHeapOopVal;)

   FreeHeap(p);

 }

 void ResourceObj::operator delete [](void* p) {

   operator delete(p);

 }

 #ifdef ASSERT

 void ResourceObj::set_allocation_type(address res, allocation_type type) {

     // Set allocation type in the resource object

     uintptr_t allocation = (uintptr_t)res;

     assert((allocation & allocation_mask) == 0, "address should be aligned to 4 bytes at least");

     assert(type <= allocation_mask, "incorrect allocation type");

     ResourceObj* resobj = (ResourceObj *)res;

     resobj->_allocation_t[0] = ~(allocation + type);

     if (type != STACK_OR_EMBEDDED) {

       // Called from operator new() and CollectionSetChooser(),

       // set verification value.

       resobj->_allocation_t[1] = (uintptr_t)&(resobj->_allocation_t[1]) + type;

     }

 }

 ResourceObj::allocation_type ResourceObj::get_allocation_type() const {

     assert(~(_allocation_t[0] | allocation_mask) == (uintptr_t)this, "lost resource object");

     return (allocation_type)((~_allocation_t[0]) & allocation_mask);

 }

 bool ResourceObj::is_type_set() const {

     allocation_type type = (allocation_type)(_allocation_t[1] & allocation_mask);

     return get_allocation_type()  == type &&

            (_allocation_t[1] - type) == (uintptr_t)(&_allocation_t[1]);

 }

 ResourceObj::ResourceObj() { // default constructor

     if (~(_allocation_t[0] | allocation_mask) != (uintptr_t)this) {

       // Operator new() is not called for allocations

       // on stack and for embedded objects.

       set_allocation_type((address)this, STACK_OR_EMBEDDED);

     } else if (allocated_on_stack()) { // STACK_OR_EMBEDDED

       // For some reason we got a value which resembles

       // an embedded or stack object (operator new() does not

       // set such type). Keep it since it is valid value

       // (even if it was garbage).

       // Ignore garbage in other fields.

     } else if (is_type_set()) {

       // Operator new() was called and type was set.

       assert(!allocated_on_stack(),

              err_msg("not embedded or stack, this(" PTR_FORMAT ") type %d a[0]=(" PTR_FORMAT ") a[1]=(" PTR_FORMAT ")",

                      this, get_allocation_type(), _allocation_t[0], _allocation_t[1]));

     } else {

       // Operator new() was not called.

       // Assume that it is embedded or stack object.

       set_allocation_type((address)this, STACK_OR_EMBEDDED);

     }

     _allocation_t[1] = 0; // Zap verification value

 }

 ResourceObj::ResourceObj(const ResourceObj& r) { // default copy constructor

     // Used in ClassFileParser::parse_constant_pool_entries() for ClassFileStream.

     // Note: garbage may resembles valid value.

     assert(~(_allocation_t[0] | allocation_mask) != (uintptr_t)this || !is_type_set(),

            err_msg("embedded or stack only, this(" PTR_FORMAT ") type %d a[0]=(" PTR_FORMAT ") a[1]=(" PTR_FORMAT ")",

                    this, get_allocation_type(), _allocation_t[0], _allocation_t[1]));

     set_allocation_type((address)this, STACK_OR_EMBEDDED);

     _allocation_t[1] = 0; // Zap verification value

 }

 ResourceObj& ResourceObj::operator=(const ResourceObj& r) { // default copy assignment

     // Used in InlineTree::ok_to_inline() for WarmCallInfo.

     assert(allocated_on_stack(),

            err_msg("copy only into local, this(" PTR_FORMAT ") type %d a[0]=(" PTR_FORMAT ") a[1]=(" PTR_FORMAT ")",

                    this, get_allocation_type(), _allocation_t[0], _allocation_t[1]));

     // Keep current _allocation_t value;

     return *this;

 }

 ResourceObj::~ResourceObj() {

     // allocated_on_C_heap() also checks that encoded (in _allocation) address == this.

     if (!allocated_on_C_heap()) { // ResourceObj::delete() will zap _allocation for C_heap.

       _allocation_t[0] = (uintptr_t)badHeapOopVal; // zap type

     }

 }

 #endif // ASSERT

 void trace_heap_malloc(size_t size, const char* name, void* p) {

   // A lock is not needed here - tty uses a lock internally

   tty->print_cr("Heap malloc " INTPTR_FORMAT " " SIZE_FORMAT " %s", p, size, name == NULL ? "" : name);

 }

 void trace_heap_free(void* p) {

   // A lock is not needed here - tty uses a lock internally

   tty->print_cr("Heap free   " INTPTR_FORMAT, p);

 }

 bool warn_new_operator = false; // see vm_main

 //--------------------------------------------------------------------------------------

 // ChunkPool implementation

 // MT-safe pool of chunks to reduce malloc/free thrashing

 // NB: not using Mutex because pools are used before Threads are initialized

 class ChunkPool: public CHeapObj<mtInternal> {

   Chunk*       _first;        // first cached Chunk; its first word points to next chunk

   size_t       _num_chunks;   // number of unused chunks in pool

   size_t       _num_used;     // number of chunks currently checked out

   const size_t _size;         // size of each chunk (must be uniform)

   // Our three static pools

   static ChunkPool* _large_pool;

   static ChunkPool* _medium_pool;

   static ChunkPool* _small_pool;

   // return first element or null

   void* get_first() {

     Chunk* c = _first;

     if (_first) {

       _first = _first->next();

       _num_chunks--;

     }

     return c;

   }

  public:

   // All chunks in a ChunkPool has the same size

    ChunkPool(size_t size) : _size(size) { _first = NULL; _num_chunks = _num_used = 0; }

   // Allocate a new chunk from the pool (might expand the pool)

   _NOINLINE_ void* allocate(size_t bytes) {

     assert(bytes == _size, "bad size");

     void* p = NULL;

     // No VM lock can be taken inside ThreadCritical lock, so os::malloc

     // should be done outside ThreadCritical lock due to NMT

     { ThreadCritical tc;

       _num_used++;

       p = get_first();

     }

     if (p == NULL) p = os::malloc(bytes, mtChunk, CURRENT_PC);

     if (p == NULL)

       vm_exit_out_of_memory(bytes, "ChunkPool::allocate");

     return p;

   }

   // Return a chunk to the pool

   void free(Chunk* chunk) {

     assert(chunk->length() + Chunk::aligned_overhead_size() == _size, "bad size");

     ThreadCritical tc;

     _num_used--;

     // Add chunk to list

     chunk->set_next(_first);

     _first = chunk;

     _num_chunks++;

   }

   // Prune the pool

   void free_all_but(size_t n) {

     Chunk* cur = NULL;

     Chunk* next;

     {

     // if we have more than n chunks, free all of them

     ThreadCritical tc;

     if (_num_chunks > n) {

       // free chunks at end of queue, for better locality

         cur = _first;

       for (size_t i = 0; i < (n - 1) && cur != NULL; i++) cur = cur->next();

       if (cur != NULL) {

           next = cur->next();

         cur->set_next(NULL);

         cur = next;

           _num_chunks = n;

         }

       }

     }

     // Free all remaining chunks, outside of ThreadCritical

     // to avoid deadlock with NMT

         while(cur != NULL) {

           next = cur->next();

       os::free(cur, mtChunk);

           cur = next;

         }

       }

   // Accessors to preallocated pool's

   static ChunkPool* large_pool()  { assert(_large_pool  != NULL, "must be initialized"); return _large_pool;  }

   static ChunkPool* medium_pool() { assert(_medium_pool != NULL, "must be initialized"); return _medium_pool; }

   static ChunkPool* small_pool()  { assert(_small_pool  != NULL, "must be initialized"); return _small_pool;  }

   static void initialize() {

     _large_pool  = new ChunkPool(Chunk::size        + Chunk::aligned_overhead_size());

     _medium_pool = new ChunkPool(Chunk::medium_size + Chunk::aligned_overhead_size());

     _small_pool  = new ChunkPool(Chunk::init_size   + Chunk::aligned_overhead_size());

   }

   static void clean() {

     enum { BlocksToKeep = 5 };

      _small_pool->free_all_but(BlocksToKeep);

      _medium_pool->free_all_but(BlocksToKeep);

      _large_pool->free_all_but(BlocksToKeep);

   }

 };

 ChunkPool* ChunkPool::_large_pool  = NULL;

 ChunkPool* ChunkPool::_medium_pool = NULL;

 ChunkPool* ChunkPool::_small_pool  = NULL;

 void chunkpool_init() {

   ChunkPool::initialize();

 }

 void

 Chunk::clean_chunk_pool() {

   ChunkPool::clean();

 }

 //--------------------------------------------------------------------------------------

 // ChunkPoolCleaner implementation

 //

 class ChunkPoolCleaner : public PeriodicTask {

   enum { CleaningInterval = 5000 };      // cleaning interval in ms

  public:

    ChunkPoolCleaner() : PeriodicTask(CleaningInterval) {}

    void task() {

      ChunkPool::clean();

    }

 };

 //--------------------------------------------------------------------------------------

 // Chunk implementation

 void* Chunk::operator new(size_t requested_size, size_t length) {

   // requested_size is equal to sizeof(Chunk) but in order for the arena

   // allocations to come out aligned as expected the size must be aligned

   // to expected arena alignment.

   // expect requested_size but if sizeof(Chunk) doesn't match isn't proper size we must align it.

   assert(ARENA_ALIGN(requested_size) == aligned_overhead_size(), "Bad alignment");

   size_t bytes = ARENA_ALIGN(requested_size) + length;

   switch (length) {

    case Chunk::size:        return ChunkPool::large_pool()->allocate(bytes);

    case Chunk::medium_size: return ChunkPool::medium_pool()->allocate(bytes);

    case Chunk::init_size:   return ChunkPool::small_pool()->allocate(bytes);

    default: {

      void *p =  os::malloc(bytes, mtChunk, CALLER_PC);

      if (p == NULL)

        vm_exit_out_of_memory(bytes, "Chunk::new");

      return p;

    }

   }

 }

 void Chunk::operator delete(void* p) {

   Chunk* c = (Chunk*)p;

   switch (c->length()) {

    case Chunk::size:        ChunkPool::large_pool()->free(c); break;

    case Chunk::medium_size: ChunkPool::medium_pool()->free(c); break;

    case Chunk::init_size:   ChunkPool::small_pool()->free(c); break;

    default:                 os::free(c, mtChunk);

   }

 }

 Chunk::Chunk(size_t length) : _len(length) {

   _next = NULL;         // Chain on the linked list

 }

 void Chunk::chop() {

   Chunk *k = this;

   while( k ) {

     Chunk *tmp = k->next();

     // clear out this chunk (to detect allocation bugs)

     if (ZapResourceArea) memset(k->bottom(), badResourceValue, k->length());

     delete k;                   // Free chunk (was malloc'd)

     k = tmp;

   }

 }

 void Chunk::next_chop() {

   _next->chop();

   _next = NULL;

 }

 void Chunk::start_chunk_pool_cleaner_task() {

 #ifdef ASSERT

   static bool task_created = false;

   assert(!task_created, "should not start chuck pool cleaner twice");

   task_created = true;

 #endif

   ChunkPoolCleaner* cleaner = new ChunkPoolCleaner();

   cleaner->enroll();

 }

 //------------------------------Arena------------------------------------------

 NOT_PRODUCT(volatile jint Arena::_instance_count = 0;)

 Arena::Arena(size_t init_size) {

   size_t round_size = (sizeof (char *)) - 1;

   init_size = (init_size+round_size) & ~round_size;

   _first = _chunk = new (init_size) Chunk(init_size);

   _hwm = _chunk->bottom();      // Save the cached hwm, max

   _max = _chunk->top();

   set_size_in_bytes(init_size);

   NOT_PRODUCT(Atomic::inc(&_instance_count);)

 }

 Arena::Arena() {

   _first = _chunk = new (Chunk::init_size) Chunk(Chunk::init_size);

   _hwm = _chunk->bottom();      // Save the cached hwm, max

   _max = _chunk->top();

   set_size_in_bytes(Chunk::init_size);

   NOT_PRODUCT(Atomic::inc(&_instance_count);)

 }

 Arena *Arena::move_contents(Arena *copy) {

   copy->destruct_contents();

   copy->_chunk = _chunk;

   copy->_hwm   = _hwm;

   copy->_max   = _max;

   copy->_first = _first;

   // workaround rare racing condition, which could double count

   // the arena size by native memory tracking

   size_t size = size_in_bytes();

   set_size_in_bytes(0);

   copy->set_size_in_bytes(size);

   // Destroy original arena

   reset();

   return copy;            // Return Arena with contents

 }

 Arena::~Arena() {

   destruct_contents();

   NOT_PRODUCT(Atomic::dec(&_instance_count);)

 }

 void* Arena::operator new(size_t size) {

   assert(false, "Use dynamic memory type binding");

   return NULL;

 }

 void* Arena::operator new (size_t size, const std::nothrow_t&  nothrow_constant) {

   assert(false, "Use dynamic memory type binding");

   return NULL;

 }

   // dynamic memory type binding

 void* Arena::operator new(size_t size, MEMFLAGS flags) {

 #ifdef ASSERT

   void* p = (void*)AllocateHeap(size, flags|otArena, CALLER_PC);

   if (PrintMallocFree) trace_heap_malloc(size, "Arena-new", p);

   return p;

 #else

   return (void *) AllocateHeap(size, flags|otArena, CALLER_PC);

 #endif

 }

 void* Arena::operator new(size_t size, const std::nothrow_t& nothrow_constant, MEMFLAGS flags) {

 #ifdef ASSERT

   void* p = os::malloc(size, flags|otArena, CALLER_PC);

   if (PrintMallocFree) trace_heap_malloc(size, "Arena-new", p);

   return p;

 #else

   return os::malloc(size, flags|otArena, CALLER_PC);

 #endif

 }

 void Arena::operator delete(void* p) {

   FreeHeap(p);

 }

 // Destroy this arenas contents and reset to empty

 void Arena::destruct_contents() {

   if (UseMallocOnly && _first != NULL) {

     char* end = _first->next() ? _first->top() : _hwm;

     free_malloced_objects(_first, _first->bottom(), end, _hwm);

   }

   // reset size before chop to avoid a rare racing condition

   // that can have total arena memory exceed total chunk memory

   set_size_in_bytes(0);

   _first->chop();

   reset();

 }

 // This is high traffic method, but many calls actually don't

 // change the size

 void Arena::set_size_in_bytes(size_t size) {

   if (_size_in_bytes != size) {

     _size_in_bytes = size;

     MemTracker::record_arena_size((address)this, size);

   }

 }

 // Total of all Chunks in arena

 size_t Arena::used() const {

   size_t sum = _chunk->length() - (_max-_hwm); // Size leftover in this Chunk

   register Chunk *k = _first;

   while( k != _chunk) {         // Whilst have Chunks in a row

     sum += k->length();         // Total size of this Chunk

     k = k->next();              // Bump along to next Chunk

   }

   return sum;                   // Return total consumed space.

 }

 void Arena::signal_out_of_memory(size_t sz, const char* whence) const {

   vm_exit_out_of_memory(sz, whence);

 }

 // Grow a new Chunk

 void* Arena::grow(size_t x, AllocFailType alloc_failmode) {

   // Get minimal required size.  Either real big, or even bigger for giant objs

   size_t len = MAX2(x, (size_t) Chunk::size);

   Chunk *k = _chunk;            // Get filled-up chunk address

   _chunk = new (len) Chunk(len);

   if (_chunk == NULL) {

     if (alloc_failmode == AllocFailStrategy::EXIT_OOM) {

       signal_out_of_memory(len * Chunk::aligned_overhead_size(), "Arena::grow");

     }

     return NULL;

   }

   if (k) k->set_next(_chunk);   // Append new chunk to end of linked list

   else _first = _chunk;

   _hwm  = _chunk->bottom();     // Save the cached hwm, max

   _max =  _chunk->top();

   set_size_in_bytes(size_in_bytes() + len);

   void* result = _hwm;

   _hwm += x;

   return result;

 }

 // Reallocate storage in Arena.

 void *Arena::Arealloc(void* old_ptr, size_t old_size, size_t new_size, AllocFailType alloc_failmode) {

   assert(new_size >= 0, "bad size");

   if (new_size == 0) return NULL;

 #ifdef ASSERT

   if (UseMallocOnly) {

     // always allocate a new object  (otherwise we'll free this one twice)

     char* copy = (char*)Amalloc(new_size, alloc_failmode);

     if (copy == NULL) {

       return NULL;

     }

     size_t n = MIN2(old_size, new_size);

     if (n > 0) memcpy(copy, old_ptr, n);

     Afree(old_ptr,old_size);    // Mostly done to keep stats accurate

     return copy;

   }

 #endif

   char *c_old = (char*)old_ptr; // Handy name

   // Stupid fast special case

   if( new_size <= old_size ) {  // Shrink in-place

     if( c_old+old_size == _hwm) // Attempt to free the excess bytes

       _hwm = c_old+new_size;    // Adjust hwm

     return c_old;

   }

   // make sure that new_size is legal

   size_t corrected_new_size = ARENA_ALIGN(new_size);

   // See if we can resize in-place

   if( (c_old+old_size == _hwm) &&       // Adjusting recent thing

       (c_old+corrected_new_size <= _max) ) {      // Still fits where it sits

     _hwm = c_old+corrected_new_size;      // Adjust hwm

     return c_old;               // Return old pointer

   }

   // Oops, got to relocate guts

   void *new_ptr = Amalloc(new_size, alloc_failmode);

   if (new_ptr == NULL) {

     return NULL;

   }

   memcpy( new_ptr, c_old, old_size );

   Afree(c_old,old_size);        // Mostly done to keep stats accurate

   return new_ptr;

 }

 // Determine if pointer belongs to this Arena or not.

 bool Arena::contains( const void *ptr ) const {

 #ifdef ASSERT

   if (UseMallocOnly) {

     // really slow, but not easy to make fast

     if (_chunk == NULL) return false;

     char** bottom = (char**)_chunk->bottom();

     for (char** p = (char**)_hwm - 1; p >= bottom; p--) {

       if (*p == ptr) return true;

     }

     for (Chunk *c = _first; c != NULL; c = c->next()) {

       if (c == _chunk) continue;  // current chunk has been processed

       char** bottom = (char**)c->bottom();

       for (char** p = (char**)c->top() - 1; p >= bottom; p--) {

         if (*p == ptr) return true;

       }

     }

     return false;

   }

 #endif

   if( (void*)_chunk->bottom() <= ptr && ptr < (void*)_hwm )

     return true;                // Check for in this chunk

   for (Chunk *c = _first; c; c = c->next()) {

     if (c == _chunk) continue;  // current chunk has been processed

     if ((void*)c->bottom() <= ptr && ptr < (void*)c->top()) {

       return true;              // Check for every chunk in Arena

     }

   }

   return false;                 // Not in any Chunk, so not in Arena

 }

 #ifdef ASSERT

 void* Arena::malloc(size_t size) {

   assert(UseMallocOnly, "shouldn't call");

   // use malloc, but save pointer in res. area for later freeing

   char** save = (char**)internal_malloc_4(sizeof(char*));

   return (*save = (char*)os::malloc(size, mtChunk));

 }

 // for debugging with UseMallocOnly

 void* Arena::internal_malloc_4(size_t x) {

   assert( (x&(sizeof(char*)-1)) == 0, "misaligned size" );

   check_for_overflow(x, "Arena::internal_malloc_4");

   if (_hwm + x > _max) {

     return grow(x);

   } else {

     char *old = _hwm;

     _hwm += x;

     return old;

   }

 }

 #endif

 //--------------------------------------------------------------------------------------

 // Non-product code

 #ifndef PRODUCT

 // The global operator new should never be called since it will usually indicate

 // a memory leak.  Use CHeapObj as the base class of such objects to make it explicit

 // that they're allocated on the C heap.

 // Commented out in product version to avoid conflicts with third-party C++ native code.

 void* operator new(size_t size){

   ShouldNotReachHere(); return 0;

 }

 void* operator new [](size_t size){

   ShouldNotReachHere(); return 0;

 }

 void* operator new(size_t size, const std::nothrow_t&  nothrow_constant){

   ShouldNotReachHere(); return 0;

 }

 void* operator new [](size_t size, std::nothrow_t&  nothrow_constant){

   ShouldNotReachHere(); return 0;

 }

 void AllocatedObj::print() const       { print_on(tty); }

 void AllocatedObj::print_value() const { print_value_on(tty); }

 void AllocatedObj::print_on(outputStream* st) const {

   st->print_cr("AllocatedObj(" INTPTR_FORMAT ")", this);

 }

 void AllocatedObj::print_value_on(outputStream* st) const {

   st->print("AllocatedObj(" INTPTR_FORMAT ")", this);

 }

 julong Arena::_bytes_allocated = 0;

 void Arena::inc_bytes_allocated(size_t x) { inc_stat_counter(&_bytes_allocated, x); }

 AllocStats::AllocStats() {

   start_mallocs      = os::num_mallocs;

   start_frees        = os::num_frees;

   start_malloc_bytes = os::alloc_bytes;

   start_mfree_bytes  = os::free_bytes;

   start_res_bytes    = Arena::_bytes_allocated;

 }

 julong  AllocStats::num_mallocs() { return os::num_mallocs - start_mallocs; }

 julong  AllocStats::alloc_bytes() { return os::alloc_bytes - start_malloc_bytes; }

 julong  AllocStats::num_frees()   { return os::num_frees - start_frees; }

 julong  AllocStats::free_bytes()  { return os::free_bytes - start_mfree_bytes; }

 julong  AllocStats::resource_bytes() { return Arena::_bytes_allocated - start_res_bytes; }

 void    AllocStats::print() {

   tty->print_cr(UINT64_FORMAT " mallocs (" UINT64_FORMAT "MB), "

                 UINT64_FORMAT" frees (" UINT64_FORMAT "MB), " UINT64_FORMAT "MB resrc",

                 num_mallocs(), alloc_bytes()/M, num_frees(), free_bytes()/M, resource_bytes()/M);

 }

 // debugging code

 inline void Arena::free_all(char** start, char** end) {

   for (char** p = start; p < end; p++) if (*p) os::free(*p);

 }

 void Arena::free_malloced_objects(Chunk* chunk, char* hwm, char* max, char* hwm2) {

   assert(UseMallocOnly, "should not call");

   // free all objects malloced since resource mark was created; resource area

   // contains their addresses

   if (chunk->next()) {

     // this chunk is full, and some others too

     for (Chunk* c = chunk->next(); c != NULL; c = c->next()) {

       char* top = c->top();

       if (c->next() == NULL) {

         top = hwm2;     // last junk is only used up to hwm2

         assert(c->contains(hwm2), "bad hwm2");

       }

       free_all((char**)c->bottom(), (char**)top);

     }

     assert(chunk->contains(hwm), "bad hwm");

     assert(chunk->contains(max), "bad max");

     free_all((char**)hwm, (char**)max);

   } else {

     // this chunk was partially used

     assert(chunk->contains(hwm), "bad hwm");

     assert(chunk->contains(hwm2), "bad hwm2");

     free_all((char**)hwm, (char**)hwm2);

   }

 }

 ReallocMark::ReallocMark() {

 #ifdef ASSERT

   Thread *thread = ThreadLocalStorage::get_thread_slow();

   _nesting = thread->resource_area()->nesting();

 #endif

 }

 void ReallocMark::check() {

 #ifdef ASSERT

   if (_nesting != Thread::current()->resource_area()->nesting()) {

     fatal("allocation bug: array could grow within nested ResourceMark");

   }

 #endif

 }

 #endif // Non-product