duke@435: /*
xdono@631:  * Copyright 2002-2008 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: //
duke@435: // PrefetchQueue is a FIFO queue of variable length (currently 8).
duke@435: //
duke@435: // We need to examine the performance penalty of variable lengths.
duke@435: // We may also want to split this into cpu dependant bits.
duke@435: //
duke@435: 
duke@435: const int PREFETCH_QUEUE_SIZE  = 8;
duke@435: 
duke@435: class PrefetchQueue : public CHeapObj {
duke@435:  private:
coleenp@548:   void* _prefetch_queue[PREFETCH_QUEUE_SIZE];
coleenp@548:   uint  _prefetch_index;
duke@435: 
duke@435:  public:
duke@435:   int length() { return PREFETCH_QUEUE_SIZE; }
duke@435: 
duke@435:   inline void clear() {
duke@435:     for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) {
duke@435:       _prefetch_queue[i] = NULL;
duke@435:     }
duke@435:     _prefetch_index = 0;
duke@435:   }
duke@435: 
coleenp@548:   template <class T> inline void* push_and_pop(T* p) {
coleenp@548:     oop o = oopDesc::load_decode_heap_oop_not_null(p);
coleenp@548:     Prefetch::write(o->mark_addr(), 0);
duke@435:     // This prefetch is intended to make sure the size field of array
duke@435:     // oops is in cache. It assumes the the object layout is
duke@435:     // mark -> klass -> size, and that mark and klass are heapword
duke@435:     // sized. If this should change, this prefetch will need updating!
coleenp@548:     Prefetch::write(o->mark_addr() + (HeapWordSize*2), 0);
duke@435:     _prefetch_queue[_prefetch_index++] = p;
duke@435:     _prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
duke@435:     return _prefetch_queue[_prefetch_index];
duke@435:   }
duke@435: 
duke@435:   // Stores a NULL pointer in the pop'd location.
coleenp@548:   inline void* pop() {
duke@435:     _prefetch_queue[_prefetch_index++] = NULL;
duke@435:     _prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
duke@435:     return _prefetch_queue[_prefetch_index];
duke@435:   }
duke@435: };