/* Soot - a J*va Optimization Framework
* Copyright (C) 2003 Navindra Umanee <navindra@cs.mcgill.ca>
*
* 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.
*/
package soot.shimple;
import soot.*;
import soot.util.*;
import java.util.*;
import soot.toolkits.scalar.*;
import soot.toolkits.graph.*;
/**
* A fully defined PhiExpr usually consists of a list of Values for
* the arguments alongst with the corresponding control flow
* predecessor for each argument. This may be provided either as a
* Soot CFG Block or more directly as the Unit at the end of the
* corresponding CFG block.
*
* <p> As much as possible we try to conform to the semantics as
* described by Cytron et al., TOPLAS Oct. 91. A Phi node such as
* "x_1 = Phi(x_2, x_3)" is eliminated by respectively adding the
* statements "x_1 = x_2" and "x_1 = x_3" at the end of the
* corresponding control flow predecessor.
*
* <p> However, due to the fact that each argument is explicitly
* associated with the control flow predecessor, there may be some
* subtle differences. We tried to make the behaviour as robust and
* transparent as possible by handling the common cases of Unit chain
* manipulations in the Shimple internal implementation of
* PatchingChain.
*
* @author Navindra Umanee
* @see
<a
* href="http://citeseer.nj.nec.com/cytron91efficiently.html">Efficiently
* Computing Static Single Assignment Form and the Control Dependence
* Graph</a>
* @see Shimple#newPhiExpr(List, List)
* @see Shimple#newPhiExpr(Local, List)
**/
public interface PhiExpr extends ShimpleExpr
{
/**
* Returns an unmodifiable, backed view of the arguments to this PhiExpr.
* Each argument is a ValueUnitPair.
*
* @see soot.toolkits.scalar.ValueUnitPair
**/
public List getArgs();
/**
* Returns a list of the values used by this PhiExpr.
**/
public List<Value> getValues();
/**
* Returns a list of the control flow predecessor Units being
* tracked by this PhiExpr
**/
public List<Unit> getPreds();
/**
* Returns the number of arguments in this PhiExpr.
**/
public int getArgCount();
/**
* Returns the argument pair for the given index. Null if
* out-of-bounds.
**/
public ValueUnitPair getArgBox(int index);
/**
* Returns the value for the given index into the PhiExpr. Null
* if out-of-bounds.
**/
public Value getValue(int index);
/**
* Returns the control flow predecessor Unit for the given index
* into the PhiExpr. Null if out-of-bounds.
**/
public Unit getPred(int index);
/**
* Returns the index of the argument associated with the given
* control flow predecessor Unit. Returns -1 if not found.
**/
public int getArgIndex(Unit predTailUnit);
/**
* Returns the argument pair corresponding to the given CFG
* predecessor. Returns null if not found.
**/
public ValueUnitPair getArgBox(Unit predTailUnit);
/**
* Get the PhiExpr argument corresponding to the given control
* flow predecessor, returns null if not available.
**/
public Value getValue(Unit predTailUnit);
/**
* Returns the index of the argument associated with the given
* control flow predecessor. Returns -1 if not found.
**/
public int getArgIndex(Block pred);
/**
* Returns the argument pair corresponding to the given CFG
* predecessor. Returns null if not found.
**/
public ValueUnitPair getArgBox(Block pred);
/**
* Get the PhiExpr argument corresponding to the given control flow
* predecessor, returns null if not available.
**/
public Value getValue(Block pred);
/**
* Modify the PhiExpr argument at the given index with the given
* information. Returns false on failure.
**/
public boolean setArg(int index, Value arg, Unit predTailUnit);
/**
* Modify the PhiExpr argument at the given index with the given
* information. Returns false on failure.
**/
public boolean setArg(int index, Value arg, Block pred);
/**
* Set the value at the given index into the PhiExpr. Returns
* false on failure.
**/
public boolean setValue(int index, Value arg);
/**
* Locate the argument assocatiated with the given CFG predecessor unit
* and set the value. Returns false on failure.
**/
public boolean setValue(Unit predTailUnit, Value arg);
/**
* Locate the argument assocatiated with the given CFG predecessor
* and set the value. Returns false on failure.
**/
public boolean setValue(Block pred, Value arg);
/**
* Update the CFG predecessor associated with the PhiExpr
* argument at the given index. Returns false on failure.
**/
public boolean setPred(int index, Unit predTailUnit);
/**
* Update the CFG predecessor associated with the PhiExpr
* argument at the given index. Returns false on failure.
**/
public boolean setPred(int index, Block pred);
/**
* Remove the argument at the given index. Returns false on
* failure.
**/
public boolean removeArg(int index);
/**
* Remove the argument corresponding to the given CFG predecessor.
* Returns false on failure.
**/
public boolean removeArg(Unit predTailUnit);
/**
* Remove the argument corresponding to the given CFG predecessor.
* Returns false on failure.
**/
public boolean removeArg(Block pred);
/**
* Remove the given argument. Returns false on failure.
**/
public boolean removeArg(ValueUnitPair arg);
/**
* Add the given argument associated with the given CFG
* predecessor. Returns false on failure.
**/
public boolean addArg(Value arg, Block pred);
/**
* Add the given argument associated with the given CFG
* predecessor. Returns false on failure.
**/
public boolean addArg(Value arg, Unit predTailUnit);
/**
* Set the block number of the Phi node.
**/
public void setBlockId(int blockId);
/**
* Returns the id number of the block from which the Phi node
* originated from.
**/
public int getBlockId();
/**
* The type of the PhiExpr is usually the same as the type of its
* arguments.
**/
public Type getType();
public void apply(Switch sw);
}