/*
* Copyright 2002-2003 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
//
// PrefetchQueue is a FIFO queue of variable length (currently 8).
//
// We need to examine the performance penalty of variable lengths.
// We may also want to split this into cpu dependant bits.
//
const int PREFETCH_QUEUE_SIZE = 8;
class PrefetchQueue : public CHeapObj {
private:
oop* _prefetch_queue[PREFETCH_QUEUE_SIZE];
unsigned int _prefetch_index;
public:
int length() { return PREFETCH_QUEUE_SIZE; }
inline void clear() {
for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) {
_prefetch_queue[i] = NULL;
}
_prefetch_index = 0;
}
inline oop* push_and_pop(oop* p) {
Prefetch::write((*p)->mark_addr(), 0);
// This prefetch is intended to make sure the size field of array
// oops is in cache. It assumes the the object layout is
// mark -> klass -> size, and that mark and klass are heapword
// sized. If this should change, this prefetch will need updating!
Prefetch::write((*p)->mark_addr() + (HeapWordSize*2), 0);
_prefetch_queue[_prefetch_index++] = p;
_prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
return _prefetch_queue[_prefetch_index];
}
// Stores a NULL pointer in the pop'd location.
inline oop* pop() {
_prefetch_queue[_prefetch_index++] = NULL;
_prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
return _prefetch_queue[_prefetch_index];
}
};