/* 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.jimple.toolkits.scalar;
import soot.options.*;
import soot.*;
import soot.jimple.*;
import soot.toolkits.scalar.*;
import soot.toolkits.graph.*;
import soot.util.*;
import java.util.*;
import soot.options.CPOptions;
public class CopyPropagator extends BodyTransformer
{
public CopyPropagator( Singletons.Global g ) {}
public static CopyPropagator v() { return G.v().soot_jimple_toolkits_scalar_CopyPropagator(); }
/** Cascaded copy propagator.
If it encounters situations of the form: A: a = ...; B: ... x = a; C:... use (x);
where a has only one definition, and x has only one definition (B), then it can
propagate immediately without checking between B and C for redefinitions
of a (namely) A because they cannot occur. In this case the propagator is global.
Otherwise, if a has multiple definitions then it only checks for redefinitions of
Propagates constants and copies in extended basic blocks.
Does not propagate stack locals when the "only-regular-locals" option is true.
*/
protected void internalTransform(Body b, String phaseName, Map opts)
{
CPOptions options = new CPOptions( opts );
StmtBody stmtBody = (StmtBody)b;
int fastCopyPropagationCount = 0;
int slowCopyPropagationCount = 0;
if(Options.v().verbose())
G.v().out.println("[" + stmtBody.getMethod().getName() +
"] Propagating copies...");
if(Options.v().time())
Timers.v().propagatorTimer.start();
Chain units = stmtBody.getUnits();
Map<Local, Integer> localToDefCount = new HashMap<Local, Integer>();
// Count number of definitions for each local.
{
Iterator stmtIt = units.iterator();
while(stmtIt.hasNext())
{
Stmt s = (Stmt) stmtIt.next();
if(s instanceof DefinitionStmt &&
((DefinitionStmt) s).getLeftOp() instanceof Local)
{
Local l = (Local) ((DefinitionStmt) s).getLeftOp();
if(!localToDefCount.containsKey(l))
localToDefCount.put(l, new Integer(1));
else
localToDefCount.put(l, new Integer(localToDefCount.get(l).intValue() + 1));
}
}
}
// ((JimpleBody) stmtBody).printDebugTo(new java.io.PrintWriter(G.v().out, true));
ExceptionalUnitGraph graph = new ExceptionalUnitGraph(stmtBody);
LocalDefs localDefs;
localDefs = new SmartLocalDefs(graph, new SimpleLiveLocals(graph));
// Perform a local propagation pass.
{
Iterator stmtIt = (new PseudoTopologicalOrderer()).newList(graph,false).iterator();
while(stmtIt.hasNext())
{
Stmt stmt = (Stmt) stmtIt.next();
Iterator useBoxIt = stmt.getUseBoxes().iterator();
while(useBoxIt.hasNext())
{
ValueBox useBox = (ValueBox) useBoxIt.next();
if(useBox.getValue() instanceof Local)
{
Local l = (Local) useBox.getValue();
if(options.only_regular_locals() && l.getName().startsWith("$"))
continue;
if(options.only_stack_locals() && !l.getName().startsWith("$"))
continue;
List<Unit> defsOfUse = localDefs.getDefsOfAt(l, stmt);
if(defsOfUse.size() == 1)
{
DefinitionStmt def = (DefinitionStmt) defsOfUse.get(0);
if(def.getRightOp() instanceof Local)
{
Local m = (Local) def.getRightOp();
if(l != m)
{
Object dcObj = localToDefCount.get(m);
if (dcObj == null)
throw new RuntimeException("Variable " + m + " used without definition!");
int defCount = ((Integer)dcObj).intValue();
if(defCount == 0)
throw new RuntimeException("Variable " + m + " used without definition!");
else if(defCount == 1)
{
useBox.setValue(m);
fastCopyPropagationCount++;
continue;
}
List<Unit> path = graph.getExtendedBasicBlockPathBetween(def, stmt);
if(path == null)
{
// no path in the extended basic block
continue;
}
Iterator<Unit> pathIt = path.iterator();
// Skip first node
pathIt.next();
// Make sure that m is not redefined along path
{
boolean isRedefined = false;
while(pathIt.hasNext())
{
Stmt s = (Stmt) pathIt.next();
if(stmt == s)
{
// Don't look at the last statement
// since it is evaluated after the uses
break;
}
if(s instanceof DefinitionStmt)
{
if(((DefinitionStmt) s).getLeftOp() == m)
{
isRedefined = true;
break;
}
}
}
if(isRedefined)
continue;
}
useBox.setValue(m);
slowCopyPropagationCount++;
}
}
}
}
}
}
}
if(Options.v().verbose())
G.v().out.println("[" + stmtBody.getMethod().getName() +
"] Propagated: " +
fastCopyPropagationCount + " fast copies " +
slowCopyPropagationCount + " slow copies");
if(Options.v().time())
Timers.v().propagatorTimer.end();
}
}