зеркало из https://github.com/mozilla/gecko-dev.git
58 строки
2.0 KiB
C++
58 строки
2.0 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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#include "PrimitiveOptimizer.h"
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#include "ControlGraph.h"
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//
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// Quickly trim primitives whose results are not used from the graph.
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// This is a quick-and-dirty implementation that misses some opportunities;
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// for example, cycles of dead primitives are not detected.
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//
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void simpleTrimDeadPrimitives(ControlGraph &cg)
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{
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cg.dfsSearch();
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ControlNode **dfsList = cg.dfsList;
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ControlNode **pcn = dfsList + cg.nNodes;
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while (pcn != dfsList) {
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ControlNode &cn = **--pcn;
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// Search the primitives backwards; remove any whose outputs are not used
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// and which are not roots.
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DoublyLinkedList<Primitive> &primitives = cn.getPrimitives();
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DoublyLinkedList<Primitive>::iterator primIter = primitives.end();
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while (!primitives.done(primIter)) {
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Primitive &p = primitives.get(primIter);
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primIter = primitives.retreat(primIter);
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if (!p.isRoot() && !p.hasConsumers())
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p.destroy();
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}
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// Search the phi nodes backwards; remove any whose outputs are not used.
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DoublyLinkedList<PhiNode> &phiNodes = cn.getPhiNodes();
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DoublyLinkedList<PhiNode>::iterator phiIter = phiNodes.end();
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while (!phiNodes.done(phiIter)) {
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PhiNode &n = phiNodes.get(phiIter);
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phiIter = phiNodes.retreat(phiIter);
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if (!n.hasConsumers())
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n.remove();
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}
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}
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}
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