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Instruction_Lookupswitch.java

00001 package ca.mcgill.sable.soot.coffi;
00002 
00003 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
00004  * Jimple, a 3-address code Java(TM) bytecode representation.        *
00005  * Copyright (C) 1997, 1998 Raja Vallee-Rai (kor@sable.mcgill.ca)    *
00006  * All rights reserved.                                              *
00007  *                                                                   *
00008  * This work was done as a project of the Sable Research Group,      *
00009  * School of Computer Science, McGill University, Canada             *
00010  * (http://www.sable.mcgill.ca/).  It is understood that any         *
00011  * modification not identified as such is not covered by the         *
00012  * preceding statement.                                              *
00013  *                                                                   *
00014  * This work is free software; you can redistribute it and/or        *
00015  * modify it under the terms of the GNU Library General Public       *
00016  * License as published by the Free Software Foundation; either      *
00017  * version 2 of the License, or (at your option) any later version.  *
00018  *                                                                   *
00019  * This work is distributed in the hope that it will be useful,      *
00020  * but WITHOUT ANY WARRANTY; without even the implied warranty of    *
00021  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU *
00022  * Library General Public License for more details.                  *
00023  *                                                                   *
00024  * You should have received a copy of the GNU Library General Public *
00025  * License along with this library; if not, write to the             *
00026  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,      *
00027  * Boston, MA  02111-1307, USA.                                      *
00028  *                                                                   *
00029  * Java is a trademark of Sun Microsystems, Inc.                     *
00030  *                                                                   *
00031  * To submit a bug report, send a comment, or get the latest news on *
00032  * this project and other Sable Research Group projects, please      *
00033  * visit the web site: http://www.sable.mcgill.ca/                   *
00034  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
00035 
00036 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
00037  * Coffi, a bytecode parser for the Java(TM) language.               *
00038  * Copyright (C) 1996, 1997 Clark Verbrugge (clump@sable.mcgill.ca). *
00039  * All rights reserved.                                              *
00040  *                                                                   *
00041  * This work was done as a project of the Sable Research Group,      *
00042  * School of Computer Science, McGill University, Canada             *
00043  * (http://www.sable.mcgill.ca/).  It is understood that any         *
00044  * modification not identified as such is not covered by the         *
00045  * preceding statement.                                              *
00046  *                                                                   *
00047  * This work is free software; you can redistribute it and/or        *
00048  * modify it under the terms of the GNU Library General Public       *
00049  * License as published by the Free Software Foundation; either      *
00050  * version 2 of the License, or (at your option) any later version.  *
00051  *                                                                   *
00052  * This work is distributed in the hope that it will be useful,      *
00053  * but WITHOUT ANY WARRANTY; without even the implied warranty of    *
00054  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU *
00055  * Library General Public License for more details.                  *
00056  *                                                                   *
00057  * You should have received a copy of the GNU Library General Public *
00058  * License along with this library; if not, write to the             *
00059  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,      *
00060  * Boston, MA  02111-1307, USA.                                      *
00061  *                                                                   *
00062  * Java is a trademark of Sun Microsystems, Inc.                     *
00063  *                                                                   *
00064  * To submit a bug report, send a comment, or get the latest news on *
00065  * this project and other Sable Research Group projects, please      *
00066  * visit the web site: http://www.sable.mcgill.ca/                   *
00067  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
00068 
00069 /*
00070  Reference Version
00071  -----------------
00072  This is the latest official version on which this file is based.
00073  The reference version is: $CoffiVersion: 1.1 $
00074                            $SootVersion: 1.beta.4 $
00075 
00076  Change History
00077  --------------
00078  A) Notes:
00079 
00080  Please use the following template.  Most recent changes should
00081  appear at the top of the list.
00082 
00083  - Modified on [date (March 1, 1900)] by [name]. [(*) if appropriate]
00084    [description of modification].
00085 
00086  Any Modification flagged with "(*)" was done as a project of the
00087  Sable Research Group, School of Computer Science,
00088  McGill University, Canada (http://www.sable.mcgill.ca/).
00089 
00090  You should add your copyright, using the following template, at
00091  the top of this file, along with other copyrights.
00092 
00093  *                                                                   *
00094  * Modifications by [name] are                                       *
00095  * Copyright (C) [year(s)] [your name (or company)].  All rights     *
00096  * reserved.                                                         *
00097  *                                                                   *
00098 
00099  B) Changes:
00100 
00101  - Modified on November 2, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca) (*)
00102    Repackaged all source files and performed extensive modifications.
00103    First initial release of Soot.
00104 
00105  - Modified on 15-Jun-1998 by Raja Vallee-Rai (kor@sable.mcgill.ca). (*)
00106    First internal release (Version 0.1).
00107 */
00108 
00109 import java.io.*;
00110 /** Instruction subclasses are used to represent parsed bytecode; each
00111  * bytecode operation has a corresponding subclass of Instruction.
00112  * <p>
00113  * Each subclass is derived from one of
00114  * <ul><li>Instruction</li>
00115  * <li>Instruction_noargs (an Instruction with no embedded arguments)</li>
00116  * <li>Instruction_byte (an Instruction with a single byte data argument)</li>
00117  * <li>Instruction_bytevar (a byte argument specifying a local variable)</li>
00118  * <li>Instruction_byteindex (a byte argument specifying a constant pool index)</li>
00119  * <li>Instruction_int (an Instruction with a single short data argument)</li>
00120  * <li>Instruction_intvar (a short argument specifying a local variable)</li>
00121  * <li>Instruction_intindex (a short argument specifying a constant pool index)</li>
00122  * <li>Instruction_intbranch (a short argument specifying a code offset)</li>
00123  * <li>Instruction_longbranch (an int argument specifying a code offset)</li>
00124  * </ul>
00125  * @author Clark Verbrugge
00126  * @see Instruction
00127  * @see Instruction_noargs
00128  * @see Instruction_byte
00129  * @see Instruction_bytevar
00130  * @see Instruction_byteindex
00131  * @see Instruction_int
00132  * @see Instruction_intvar
00133  * @see Instruction_intindex
00134  * @see Instruction_intbranch
00135  * @see Instruction_longbranch
00136  * @see Instruction_Unknown
00137  */
00138 class Instruction_Lookupswitch extends Instruction {
00139    public byte pad;  // number of bytes used for padding
00140    public int default_offset;
00141    public int npairs;
00142    public int match_offsets[];
00143    public Instruction default_inst;
00144    public Instruction match_insts[];
00145    public Instruction_Lookupswitch() { super((byte)ByteCode.LOOKUPSWITCH); name = "lookupswitch"; branches = true; }   
00146    public Instruction[] branchpoints(Instruction next) {
00147       Instruction i[] = new Instruction[npairs+1];
00148       int j;
00149       i[0] = default_inst;
00150       for (j=1;j<npairs+1;j++)
00151          i[j] = match_insts[j-1];
00152       return i;
00153    }   
00154    public int compile(byte bc[],int index) {
00155       int i;
00156       bc[index++] = code;
00157       // insert padding so next instruction is on a 4-byte boundary
00158       for (i=0;i<pad;i++)
00159          bc[index++] = 0;
00160       if (default_inst!=null)
00161          index = intToBytes(default_inst.label-label,bc,index);
00162       else
00163          index = intToBytes(default_offset,bc,index);
00164       index = intToBytes(npairs,bc,index);
00165       for (i=0;i<npairs;i++) {
00166          index = intToBytes(match_offsets[i*2],bc,index);
00167          if (match_insts[i]!=null)
00168             index = intToBytes((match_insts[i]).label-label,bc,index);
00169          else
00170             index = intToBytes(match_offsets[i*2+1],bc,index);
00171       }
00172       return index;
00173    }   
00174    public int nextOffset(int curr) {
00175       int i,j,baseindex,siz=0;
00176       baseindex = curr;
00177       i = (curr+1) % 4;
00178       if (i != 0)
00179          siz = (4 - i);
00180       return (curr + siz + 9 + npairs*8);
00181    }   
00182    public void offsetToPointer(ByteCode bc) {
00183       int i;
00184       default_inst = bc.locateInst(default_offset+label);
00185       if (default_inst==null) {
00186          System.out.println("Warning: can't locate target of instruction");
00187          System.out.println(" which should be at byte address " + (label+default_offset));
00188       } else
00189          default_inst.labelled = true;
00190       if (npairs>0) {
00191          match_insts = new Instruction[npairs];
00192          for (i=0;i<npairs;i++) {
00193             match_insts[i] = bc.locateInst(match_offsets[i*2+1]+label);
00194             if (match_insts[i]==null) {
00195                System.out.println("Warning: can't locate target of instruction");
00196                System.out.println(" which should be at byte address " +
00197                                   (label+match_offsets[i*2+1]));
00198             } else
00199                match_insts[i].labelled = true;
00200          }
00201       }
00202    }   
00203    public int parse(byte bc[],int index) {
00204       // first figure out padding to next 4-byte quantity
00205       int i,j,baseindex;
00206       baseindex = index;
00207       i = index % 4;
00208       if (i != 0)
00209          pad = (byte)(4 - i);
00210       else
00211          pad = (byte)0;
00212       index += pad;
00213       default_offset = getInt(bc,index);
00214       index += 4;
00215       npairs = getInt(bc,index);
00216       index += 4;
00217       if (npairs>0) {
00218          match_offsets = new int[npairs*2];
00219          j = 0;
00220          do {
00221             match_offsets[j] = getInt(bc,index);
00222             j++;
00223             index += 4;
00224             match_offsets[j] = getInt(bc,index);
00225             index += 4;
00226             j++;
00227          } while(j<npairs*2);
00228       }
00229       return index;
00230    }   
00231    public String toString(cp_info constant_pool[]) {
00232       // first figure out padding to next 4-byte quantity
00233       String args;
00234       int i;
00235       args = super.toString(constant_pool) + argsep + "(" +
00236          Integer.toString(pad) + ")";
00237       args = args + argsep + Integer.toString(default_inst.label);
00238       args = args + argsep + Integer.toString(npairs) + ": ";
00239       for (i=0;i<npairs;i++)
00240          args = args + "case " + Integer.toString(match_offsets[i*2]) +
00241             ": label_" + Integer.toString(match_insts[i].label);
00242       return args;
00243    }   
00244 }

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