path: root/plugins/java-decompiler/engine/src/org/jetbrains/java/decompiler/modules/decompiler/vars/VarVersionsProcessor.java

/*
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jetbrains.java.decompiler.modules.decompiler.vars;

import org.jetbrains.java.decompiler.code.CodeConstants;
import org.jetbrains.java.decompiler.main.DecompilerContext;
import org.jetbrains.java.decompiler.main.collectors.CounterContainer;
import org.jetbrains.java.decompiler.modules.decompiler.exps.ConstExprent;
import org.jetbrains.java.decompiler.modules.decompiler.exps.Exprent;
import org.jetbrains.java.decompiler.modules.decompiler.exps.VarExprent;
import org.jetbrains.java.decompiler.modules.decompiler.sforms.DirectGraph;
import org.jetbrains.java.decompiler.modules.decompiler.sforms.FlattenStatementsHelper;
import org.jetbrains.java.decompiler.modules.decompiler.sforms.SSAConstructorSparseEx;
import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement;
import org.jetbrains.java.decompiler.struct.StructMethod;
import org.jetbrains.java.decompiler.struct.gen.VarType;
import org.jetbrains.java.decompiler.util.FastSparseSetFactory.FastSparseSet;

import java.util.*;
import java.util.Map.Entry;

public class VarVersionsProcessor {

  private HashMap<Integer, Integer> mapOriginalVarIndices = new HashMap<Integer, Integer>();

  private VarTypeProcessor typeproc;

  public void setVarVersions(RootStatement root) {

    StructMethod mt = (StructMethod)DecompilerContext.getProperty(DecompilerContext.CURRENT_METHOD);

    SSAConstructorSparseEx ssa = new SSAConstructorSparseEx();
    ssa.splitVariables(root, mt);

    FlattenStatementsHelper flatthelper = new FlattenStatementsHelper();
    DirectGraph dgraph = flatthelper.buildDirectGraph(root);

    //		System.out.println("~~~~~~~~~~~~~~~~~~~~~~ \r\n"+root.toJava());

    mergePhiVersions(ssa, dgraph);

    //		System.out.println("~~~~~~~~~~~~~~~~~~~~~~ \r\n"+root.toJava());

    typeproc = new VarTypeProcessor();
    typeproc.calculateVarTypes(root, dgraph);

    simpleMerge(typeproc, dgraph, mt);

    // FIXME: advanced merging

    eliminateNonJavaTypes(typeproc);

    setNewVarIndices(typeproc, dgraph);
  }

  private static void mergePhiVersions(SSAConstructorSparseEx ssa, DirectGraph dgraph) {

    // collect phi versions
    List<HashSet<VarVersionPaar>> lst = new ArrayList<HashSet<VarVersionPaar>>();
    for (Entry<VarVersionPaar, FastSparseSet<Integer>> ent : ssa.getPhi().entrySet()) {
      HashSet<VarVersionPaar> set = new HashSet<VarVersionPaar>();
      set.add(ent.getKey());
      for (Integer vers : ent.getValue()) {
        set.add(new VarVersionPaar(ent.getKey().var, vers.intValue()));
      }

      for (int i = lst.size() - 1; i >= 0; i--) {
        HashSet<VarVersionPaar> tset = lst.get(i);
        HashSet<VarVersionPaar> intersection = new HashSet<VarVersionPaar>(set);
        intersection.retainAll(tset);

        if (!intersection.isEmpty()) {
          set.addAll(tset);
          lst.remove(i);
        }
      }

      lst.add(set);
    }

    final HashMap<VarVersionPaar, Integer> phivers = new HashMap<VarVersionPaar, Integer>();
    for (HashSet<VarVersionPaar> set : lst) {
      int min = Integer.MAX_VALUE;
      for (VarVersionPaar paar : set) {
        if (paar.version < min) {
          min = paar.version;
        }
      }

      for (VarVersionPaar paar : set) {
        phivers.put(new VarVersionPaar(paar.var, paar.version), min);
      }
    }


    dgraph.iterateExprents(new DirectGraph.ExprentIterator() {
      public int processExprent(Exprent exprent) {
        List<Exprent> lst = exprent.getAllExprents(true);
        lst.add(exprent);

        for (Exprent expr : lst) {
          if (expr.type == Exprent.EXPRENT_VAR) {
            VarExprent var = (VarExprent)expr;
            Integer vers = phivers.get(new VarVersionPaar(var));
            if (vers != null) {
              var.setVersion(vers);
            }
          }
        }
        return 0;
      }
    });
  }

  private static void eliminateNonJavaTypes(VarTypeProcessor typeproc) {

    HashMap<VarVersionPaar, VarType> mapExprentMaxTypes = typeproc.getMapExprentMaxTypes();
    HashMap<VarVersionPaar, VarType> mapExprentMinTypes = typeproc.getMapExprentMinTypes();

    HashSet<VarVersionPaar> set = new HashSet<VarVersionPaar>(mapExprentMinTypes.keySet());
    for (VarVersionPaar paar : set) {
      VarType type = mapExprentMinTypes.get(paar);
      VarType maxtype = mapExprentMaxTypes.get(paar);

      if (type.type == CodeConstants.TYPE_BYTECHAR || type.type == CodeConstants.TYPE_SHORTCHAR) {
        if (maxtype != null && maxtype.type == CodeConstants.TYPE_CHAR) {
          type = VarType.VARTYPE_CHAR;
        }
        else {
          type = type.type == CodeConstants.TYPE_BYTECHAR ? VarType.VARTYPE_BYTE : VarType.VARTYPE_SHORT;
        }
        mapExprentMinTypes.put(paar, type);
        //} else if(type.type == CodeConstants.TYPE_CHAR && (maxtype == null || maxtype.type == CodeConstants.TYPE_INT)) { // when possible, lift char to int
        //	mapExprentMinTypes.put(paar, VarType.VARTYPE_INT);
      }
      else if (type.type == CodeConstants.TYPE_NULL) {
        mapExprentMinTypes.put(paar, VarType.VARTYPE_OBJECT);
      }
    }
  }

  private static void simpleMerge(VarTypeProcessor typeproc, DirectGraph dgraph, StructMethod mt) {

    HashMap<VarVersionPaar, VarType> mapExprentMaxTypes = typeproc.getMapExprentMaxTypes();
    HashMap<VarVersionPaar, VarType> mapExprentMinTypes = typeproc.getMapExprentMinTypes();

    HashMap<Integer, HashSet<Integer>> mapVarVersions = new HashMap<Integer, HashSet<Integer>>();

    for (VarVersionPaar varpaar : mapExprentMinTypes.keySet()) {
      if (varpaar.version >= 0) {  // don't merge constants
        HashSet<Integer> set = mapVarVersions.get(varpaar.var);
        if (set == null) {
          set = new HashSet<Integer>();
          mapVarVersions.put(varpaar.var, set);
        }
        set.add(varpaar.version);
      }
    }

    boolean is_method_static = mt.hasModifier(CodeConstants.ACC_STATIC);

    final HashMap<VarVersionPaar, Integer> mapMergedVersions = new HashMap<VarVersionPaar, Integer>();

    for (Entry<Integer, HashSet<Integer>> ent : mapVarVersions.entrySet()) {

      if (ent.getValue().size() > 1) {
        List<Integer> lstVersions = new ArrayList<Integer>(ent.getValue());
        Collections.sort(lstVersions);

        for (int i = 0; i < lstVersions.size(); i++) {
          VarVersionPaar firstpaar = new VarVersionPaar(ent.getKey(), lstVersions.get(i));
          VarType firsttype = mapExprentMinTypes.get(firstpaar);

          if (firstpaar.var == 0 && firstpaar.version == 1 && !is_method_static) {
            continue; // don't merge 'this' variable
          }

          for (int j = i + 1; j < lstVersions.size(); j++) {
            VarVersionPaar secpaar = new VarVersionPaar(ent.getKey(), lstVersions.get(j));
            VarType sectype = mapExprentMinTypes.get(secpaar);

            if (firsttype.equals(sectype) || (firsttype.equals(VarType.VARTYPE_NULL) && sectype.type == CodeConstants.TYPE_OBJECT)
                || (sectype.equals(VarType.VARTYPE_NULL) && firsttype.type == CodeConstants.TYPE_OBJECT)) {

              VarType firstMaxType = mapExprentMaxTypes.get(firstpaar);
              VarType secMaxType = mapExprentMaxTypes.get(secpaar);
              mapExprentMaxTypes.put(firstpaar, firstMaxType == null ? secMaxType :
                                                (secMaxType == null ? firstMaxType : VarType.getCommonMinType(firstMaxType, secMaxType)));


              mapMergedVersions.put(secpaar, firstpaar.version);
              mapExprentMaxTypes.remove(secpaar);
              mapExprentMinTypes.remove(secpaar);

              if (firsttype.equals(VarType.VARTYPE_NULL)) {
                mapExprentMinTypes.put(firstpaar, sectype);
                firsttype = sectype;
              }

              typeproc.getMapFinalVars().put(firstpaar, VarTypeProcessor.VAR_NONFINAL);

              lstVersions.remove(j);
              j--;
            }
          }
        }
      }
    }

    if (!mapMergedVersions.isEmpty()) {
      dgraph.iterateExprents(new DirectGraph.ExprentIterator() {
        public int processExprent(Exprent exprent) {
          List<Exprent> lst = exprent.getAllExprents(true);
          lst.add(exprent);

          for (Exprent expr : lst) {
            if (expr.type == Exprent.EXPRENT_VAR) {
              VarExprent varex = (VarExprent)expr;
              Integer newversion = mapMergedVersions.get(new VarVersionPaar(varex));
              if (newversion != null) {
                varex.setVersion(newversion);
              }
            }
          }

          return 0;
        }
      });
    }
  }

  private void setNewVarIndices(VarTypeProcessor typeproc, DirectGraph dgraph) {

    final HashMap<VarVersionPaar, VarType> mapExprentMaxTypes = typeproc.getMapExprentMaxTypes();
    HashMap<VarVersionPaar, VarType> mapExprentMinTypes = typeproc.getMapExprentMinTypes();
    HashMap<VarVersionPaar, Integer> mapFinalVars = typeproc.getMapFinalVars();

    CounterContainer ccon = DecompilerContext.getCounterContainer();

    final HashMap<VarVersionPaar, Integer> mapVarPaar = new HashMap<VarVersionPaar, Integer>();
    HashMap<Integer, Integer> mapOriginalVarIndices = new HashMap<Integer, Integer>();

    // map var-version paars on new var indexes
    HashSet<VarVersionPaar> set = new HashSet<VarVersionPaar>(mapExprentMinTypes.keySet());
    for (VarVersionPaar vpaar : set) {

      if (vpaar.version >= 0) {
        int newindex = vpaar.version == 1 ? vpaar.var :
                       ccon.getCounterAndIncrement(CounterContainer.VAR_COUNTER);

        VarVersionPaar newvar = new VarVersionPaar(newindex, 0);

        mapExprentMinTypes.put(newvar, mapExprentMinTypes.get(vpaar));
        mapExprentMaxTypes.put(newvar, mapExprentMaxTypes.get(vpaar));

        if (mapFinalVars.containsKey(vpaar)) {
          mapFinalVars.put(newvar, mapFinalVars.remove(vpaar));
        }

        mapVarPaar.put(vpaar, newindex);
        mapOriginalVarIndices.put(newindex, vpaar.var);
      }
    }

    // set new vars
    dgraph.iterateExprents(new DirectGraph.ExprentIterator() {
      public int processExprent(Exprent exprent) {
        List<Exprent> lst = exprent.getAllExprents(true);
        lst.add(exprent);

        for (Exprent expr : lst) {
          if (expr.type == Exprent.EXPRENT_VAR) {
            VarExprent varex = (VarExprent)expr;
            Integer newvarindex = mapVarPaar.get(new VarVersionPaar(varex));
            if (newvarindex != null) {
              varex.setIndex(newvarindex);
              varex.setVersion(0);
            }
          }
          else if (expr.type == Exprent.EXPRENT_CONST) {
            VarType maxType = mapExprentMaxTypes.get(new VarVersionPaar(expr.id, -1));
            if (maxType != null && maxType.equals(VarType.VARTYPE_CHAR)) {
              ((ConstExprent)expr).setConsttype(maxType);
            }
          }
        }

        return 0;
      }
    });

    this.mapOriginalVarIndices = mapOriginalVarIndices;
  }

  public VarType getVarType(VarVersionPaar varpaar) {
    return typeproc == null ? null : typeproc.getVarType(varpaar);
  }

  public void setVarType(VarVersionPaar varpaar, VarType type) {
    typeproc.setVarType(varpaar, type);
  }

  public int getVarFinal(VarVersionPaar varpaar) {

    int ret = VarTypeProcessor.VAR_FINAL;
    if (typeproc != null) {
      Integer fin = typeproc.getMapFinalVars().get(varpaar);
      ret = fin == null ? VarTypeProcessor.VAR_FINAL : fin.intValue();
    }

    return ret;
  }

  public void setVarFinal(VarVersionPaar varpaar, int finaltype) {
    typeproc.getMapFinalVars().put(varpaar, finaltype);
  }

  public HashMap<Integer, Integer> getMapOriginalVarIndices() {
    return mapOriginalVarIndices;
  }
}