soot.toolkits.scalar.FlowAnalysis Maven / Gradle / Ivy
/* Soot - a J*va Optimization Framework
* Copyright (C) 1997-1999 Raja Vallee-Rai
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the Sable Research Group and others 1997-1999.
* See the 'credits' file distributed with Soot for the complete list of
* contributors. (Soot is distributed at http://www.sable.mcgill.ca/soot)
*/
package soot.toolkits.scalar;
import java.util.HashMap;
import java.util.Map;
import soot.toolkits.graph.DirectedGraph;
import soot.toolkits.graph.Orderer;
import soot.toolkits.graph.PseudoTopologicalOrderer;
/** An abstract class providing a framework for carrying out dataflow analysis.
* Subclassing either BackwardFlowAnalysis or ForwardFlowAnalysis and providing
* implementations for the abstract methods will allow Soot to compute the
* corresponding flow analysis. */
public abstract class FlowAnalysis extends AbstractFlowAnalysis
{
/** Maps graph nodes to OUT sets. */
protected Map unitToAfterFlow;
/** Filtered: Maps graph nodes to OUT sets. */
protected Map filterUnitToAfterFlow;
/** Constructs a flow analysis on the given DirectedGraph. */
public FlowAnalysis(DirectedGraph graph)
{
super(graph);
unitToAfterFlow = new HashMap(graph.size() * 2 + 1, 0.7f);
}
/** Given the merge of the out sets, compute the in set for s (or in to out, depending on direction).
*
* This function often causes confusion, because the same interface
* is used for both forward and backward flow analyses. The first
* parameter is always the argument to the flow function (i.e. it
* is the "in" set in a forward analysis and the "out" set in a
* backward analysis), and the third parameter is always the result
* of the flow function (i.e. it is the "out" set in a forward
* analysis and the "in" set in a backward analysis).
* */
protected abstract void flowThrough(A in, N d, A out);
/** Accessor function returning value of OUT set for s. */
public A getFlowAfter(N s)
{
return unitToAfterFlow.get(s);
}
/**
* Default implementation constructing a PseudoTopologicalOrderer.
* @return an Orderer to order the nodes for the fixed-point iteration
*/
protected Orderer constructOrderer() {
return new PseudoTopologicalOrderer();
}
}