soot.shimple.PhiExpr Maven / Gradle / Ivy
package soot.shimple;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2003 Navindra Umanee
* %%
* This program 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 program 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 General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import java.util.List;
import soot.Local;
import soot.Type;
import soot.Unit;
import soot.Value;
import soot.toolkits.graph.Block;
import soot.toolkits.scalar.ValueUnitPair;
import soot.util.Switch;
/**
* 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.
*
*
* 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.
*
*
* 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 Efficiently Computing Static Single Assignment Form and
* the Control Dependence Graph
* @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 getValues();
/**
* Returns a list of the control flow predecessor Units being tracked by this PhiExpr
**/
public List 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 associated with the given CFG predecessor unit and set the value. Returns false on failure.
**/
public boolean setValue(Unit predTailUnit, Value arg);
/**
* Locate the argument associated 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);
}