74 lines
2.5 KiB
Java
74 lines
2.5 KiB
Java
/******************************************************************************
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* Copyright (c) 2002 - 2014 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*****************************************************************************/
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package com.ibm.wala.cfg.exc.intra;
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import com.ibm.wala.cfg.ControlFlowGraph;
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import com.ibm.wala.dataflow.graph.IKilldallFramework;
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import com.ibm.wala.ssa.IR;
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import com.ibm.wala.ssa.ISSABasicBlock;
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import com.ibm.wala.ssa.SSAInstruction;
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import com.ibm.wala.util.graph.Acyclic;
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import com.ibm.wala.util.graph.Graph;
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import com.ibm.wala.util.intset.IBinaryNaturalRelation;
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import com.ibm.wala.util.intset.IntPair;
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/**
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* Nullpointer analysis - NOT A REAL KILDALL framework instance, because the transfer
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* functions are not distribute (similar to constant propagation). Therefore we remove
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* back edges in the flow graph.
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*
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* @author Juergen Graf <graf@kit.edu>
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*
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*/
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class NullPointerFrameWork<T extends ISSABasicBlock> implements IKilldallFramework<T, NullPointerState> {
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private final Graph<T> flow;
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private final NullPointerTransferFunctionProvider<T> transferFunct;
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NullPointerFrameWork(ControlFlowGraph<SSAInstruction, T> cfg, IR ir) {
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final IBinaryNaturalRelation backEdges = Acyclic.computeBackEdges(cfg, cfg.entry());
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boolean hasBackEdge = backEdges.iterator().hasNext();
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if (hasBackEdge) {
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MutableCFG<SSAInstruction, T> cfg2 = MutableCFG.copyFrom(cfg);
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for (IntPair edge : backEdges) {
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T from = cfg2.getNode(edge.getX());
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T to = cfg2.getNode(edge.getY());
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cfg2.removeEdge(from, to);
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cfg2.addEdge(from, cfg.exit());
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}
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this.flow = cfg2;
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} else {
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this.flow = cfg;
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}
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this.transferFunct = new NullPointerTransferFunctionProvider<T>(cfg, ir);
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}
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/* (non-Javadoc)
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* @see com.ibm.wala.dataflow.graph.IKilldallFramework#getFlowGraph()
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*/
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@Override
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public Graph<T> getFlowGraph() {
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return flow;
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}
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/* (non-Javadoc)
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* @see com.ibm.wala.dataflow.graph.IKilldallFramework#getTransferFunctionProvider()
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*/
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@Override
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public NullPointerTransferFunctionProvider<T> getTransferFunctionProvider() {
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return transferFunct;
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}
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} |