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68 lines
2.4 KiB
C++
68 lines
2.4 KiB
C++
/*
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* Copyright (c) 2002, 2008, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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//
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// PrefetchQueue is a FIFO queue of variable length (currently 8).
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//
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// We need to examine the performance penalty of variable lengths.
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// We may also want to split this into cpu dependent bits.
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//
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const int PREFETCH_QUEUE_SIZE = 8;
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class PrefetchQueue : public CHeapObj {
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private:
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void* _prefetch_queue[PREFETCH_QUEUE_SIZE];
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uint _prefetch_index;
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public:
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int length() { return PREFETCH_QUEUE_SIZE; }
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inline void clear() {
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for(int i=0; i<PREFETCH_QUEUE_SIZE; i++) {
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_prefetch_queue[i] = NULL;
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}
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_prefetch_index = 0;
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}
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template <class T> inline void* push_and_pop(T* p) {
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oop o = oopDesc::load_decode_heap_oop_not_null(p);
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Prefetch::write(o->mark_addr(), 0);
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// This prefetch is intended to make sure the size field of array
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// oops is in cache. It assumes the the object layout is
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// mark -> klass -> size, and that mark and klass are heapword
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// sized. If this should change, this prefetch will need updating!
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Prefetch::write(o->mark_addr() + (HeapWordSize*2), 0);
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_prefetch_queue[_prefetch_index++] = p;
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_prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
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return _prefetch_queue[_prefetch_index];
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}
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// Stores a NULL pointer in the pop'd location.
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inline void* pop() {
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_prefetch_queue[_prefetch_index++] = NULL;
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_prefetch_index &= (PREFETCH_QUEUE_SIZE-1);
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return _prefetch_queue[_prefetch_index];
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}
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};
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