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    • soot.dava.toolkits.base.AST.transformations.IfElseSplitter Maven / Gradle / Ivy

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    package soot.dava.toolkits.base.AST.transformations;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 1997 - 2018 Raja Vallée-Rai and others
 * %%
 * 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.Iterator;
import java.util.List;

import soot.G;
import soot.dava.DecompilationException;
import soot.dava.internal.AST.ASTCondition;
import soot.dava.internal.AST.ASTIfElseNode;
import soot.dava.internal.AST.ASTIfNode;
import soot.dava.internal.AST.ASTMethodNode;
import soot.dava.internal.AST.ASTNode;
import soot.dava.internal.AST.ASTStatementSequenceNode;
import soot.dava.internal.AST.ASTTryNode;
import soot.dava.internal.SET.SETNodeLabel;
import soot.dava.internal.asg.AugmentedStmt;
import soot.dava.internal.javaRep.DAbruptStmt;
import soot.dava.toolkits.base.AST.analysis.DepthFirstAdapter;
import soot.dava.toolkits.base.AST.traversals.ASTParentNodeFinder;
import soot.jimple.ReturnStmt;
import soot.jimple.ReturnVoidStmt;
import soot.jimple.Stmt;

/*
 *  look for patterns of the form
 *   if(cond1){                  if(cond1){
 *      BodyA                        BodyA
 *      abrupt       ---->           abrupt
 *   }                           }
 *   else{                       BodyB
 *      BodyB
 *   }
 *
 *   Things to ensure:
 *       If abrupt then check BodyA does not target a label on the ifelse
 *
 * ALWAYS  Make sure BodyB does not target a label on the ifelse
 *
 *    If the pattern is NOT matched check the reverse i.e. maybe BodyB
 *    has the abrupt statement in that case we just negated the condition
 */
public class IfElseSplitter extends DepthFirstAdapter {
  public static boolean DEBUG = false;
  boolean targeted = false;
  ASTMethodNode methodNode;

  ASTNode parent;
  ASTIfElseNode toReplace;
  ASTIfNode toInsert;
  List bodyAfterInsert;
  boolean transform = false;

  public IfElseSplitter() {

  }

  public IfElseSplitter(boolean verbose) {
    super(verbose);
  }

  public void inASTMethodNode(ASTMethodNode node) {
    methodNode = node;
  }

  public void outASTMethodNode(ASTMethodNode a) {
    if (!transform) {
      return;
    }

    List parentBodies = parent.get_SubBodies();
    Iterator it = parentBodies.iterator();
    while (it.hasNext()) {
      List subBody = null;
      if (parent instanceof ASTTryNode) {
        subBody = (List) ((ASTTryNode.container) it.next()).o;
      } else {
        subBody = (List) it.next();
      }

      if (subBody.indexOf(toReplace) > -1) {
        // in the subBody list the node is present
        subBody.add(subBody.indexOf(toReplace), toInsert);
        subBody.addAll(subBody.indexOf(toReplace), bodyAfterInsert);
        subBody.remove(toReplace);
        G.v().ASTTransformations_modified = true;
      }
    }

  }

  public void outASTIfElseNode(ASTIfElseNode node) {
    // if some pattern has already matched cant do another one in this go
    if (transform) {
      return;
    }

    List subBodies = node.get_SubBodies();
    if (subBodies.size() != 2) {
      throw new DecompilationException("IfelseNode without two subBodies. report to developer");
    }

    List ifBody = (List) subBodies.get(0);
    List elseBody = (List) subBodies.get(1);

    boolean patternMatched = tryBodyPattern(ifBody, node.get_Label(), elseBody);
    List newIfBody = null;
    List outerScopeBody = null;
    boolean negateIfCondition = false;

    if (patternMatched) {
      if (DEBUG) {
        System.out.println("First pattern matched");
      }
      newIfBody = ifBody;
      outerScopeBody = elseBody;
      negateIfCondition = false;
    } else {
      patternMatched = tryBodyPattern(elseBody, node.get_Label(), ifBody);
      if (patternMatched) {
        if (DEBUG) {
          System.out.println("Second pattern matched");
        }

        newIfBody = elseBody;
        outerScopeBody = ifBody;
        negateIfCondition = true;
      }
    }

    // if at this point newIfBody and outerScopeBody are non null we got ourselves a transformation :)
    if (newIfBody != null && outerScopeBody != null) {
      ASTCondition cond = node.get_Condition();
      if (negateIfCondition) {
        cond.flip();
      }

      ASTIfNode newNode = new ASTIfNode(node.get_Label(), cond, newIfBody);
      if (DEBUG) {
        System.out.println("New IF Node is: " + newNode.toString());
        System.out.println("Outer scope body list is:\n");
        for (int i = 0; i < outerScopeBody.size(); i++) {
          System.out.println("\n\n " + outerScopeBody.get(i).toString());
        }
      }

      ASTParentNodeFinder finder = new ASTParentNodeFinder();
      methodNode.apply(finder);
      Object returned = finder.getParentOf(node);
      if (returned == null) {
        // coundnt find parent so cant do anything
        return;
      }

      /*
       * Setting globals since everything is ready for transformation BECAUSE we cant modify the parent here we are going to
       * do some bad coding style store the information needed for this into globals set a flag and the outASTMethod checks
       * for this
       */
      parent = (ASTNode) returned;
      toReplace = node;
      toInsert = newNode;
      bodyAfterInsert = outerScopeBody;
      transform = true;

    }
  }

  public boolean tryBodyPattern(List body, SETNodeLabel label, List otherBody) {
    Stmt lastStmt = getLastStmt(body);
    if (lastStmt == null) {
      // dont have a last stmt so cant match pattern
      return false;
    }

    if (!(lastStmt instanceof ReturnStmt || lastStmt instanceof ReturnVoidStmt || lastStmt instanceof DAbruptStmt)) {
      // lastStmt is not an abrupt stmt
      return false;
    }

    if (bodyTargetsLabel(label, body) || bodyTargetsLabel(label, otherBody)) {
      // one of the bodies targets the label on the ifelse cant match pattern
      return false;
    }

    // pattern matched
    return true;
  }

  /*
   * Check that label is non null and the string inside is non null... if yes return false Check that the given list
   * (sequeneof ASTNodes have no abrupt edge targeting the label.
   *
   */
  public boolean bodyTargetsLabel(SETNodeLabel label, List body) {
    // no SETNodeLabel is good
    if (label == null) {
      return false;
    }

    // SETNodeLabel but with no string is also good
    if (label.toString() == null) {
      return false;
    }

    final String strLabel = label.toString();

    // go through the body use traversal to find whether there is an abrupt stmt targeting this
    Iterator it = body.iterator();

    targeted = false;
    while (it.hasNext()) {
      ASTNode temp = (ASTNode) it.next();

      temp.apply(new DepthFirstAdapter() {
        // set targeted to true if DAbruptStmt targets it
        public void inStmt(Stmt s) {
          // only interested in abrupt stmts
          if (!(s instanceof DAbruptStmt)) {
            return;
          }

          DAbruptStmt abrupt = (DAbruptStmt) s;
          SETNodeLabel label = abrupt.getLabel();
          if (label != null && label.toString() != null && label.toString().equals(strLabel)) {
            targeted = true;

          }
        }
      });

      if (targeted) {
        break;
      }
    }
    return targeted;
  }

  /*
   * Given a list of ASTNodes see if the last astnode is a StatementSequenceNode if not return null else, return the last
   * statement in this node
   */
  public Stmt getLastStmt(List body) {
    if (body.size() == 0) {
      return null;
    }

    ASTNode lastNode = (ASTNode) body.get(body.size() - 1);
    if (!(lastNode instanceof ASTStatementSequenceNode)) {
      return null;
    }

    ASTStatementSequenceNode stmtNode = (ASTStatementSequenceNode) lastNode;
    List stmts = stmtNode.getStatements();
    if (stmts.size() == 0) {
      return null;
    }

    AugmentedStmt lastStmt = stmts.get(stmts.size() - 1);
    return lastStmt.get_Stmt();
  }
}
    
    
    
    

    




    
    
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