Instruction_Tableswitch.java Source File

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_Tableswitch extends Instruction {
00139    public byte pad;  // number of bytes used for padding
00140    public int default_offset;
00141    public int low;
00142    public int high;
00143    public int jump_offsets[];
00144    public Instruction default_inst;
00145    public Instruction jump_insts[];
00146    public Instruction_Tableswitch() {
00147       super((byte)ByteCode.TABLESWITCH);
00148       name = "tableswitch";
00149       branches = true;
00150    }   
00151    public Instruction[] branchpoints(Instruction next) {
00152       Instruction i[] = new Instruction[high-low+2];
00153       int j;
00154       i[0] = default_inst;
00155       for (j=1;j<high-low+2;j++)
00156          i[j] = jump_insts[j-1];
00157       return i;
00158    }   
00159    public int compile(byte bc[],int index) {
00160       int i;
00161       bc[index++] = code;
00162       // insert padding so next instruction is on a 4-byte boundary
00163       for (i=0;i<pad;i++)
00164          bc[index++] = 0;
00165       if (default_inst!=null)
00166          index = intToBytes(default_inst.label-label,bc,index);
00167       else
00168          index = intToBytes(default_offset,bc,index);
00169       index = intToBytes(low,bc,index);
00170       index = intToBytes(high,bc,index);
00171       for (i=0;i<=high-low;i++) {
00172          if (jump_insts[i]!=null)
00173             index = intToBytes((jump_insts[i]).label-label,bc,index);
00174          else
00175             index = intToBytes(jump_offsets[i],bc,index);
00176       }
00177       return index;
00178    }   
00179    public int nextOffset(int curr) {
00180       int i,j,baseindex,siz=0;
00181       baseindex = curr;
00182       i = (curr+1) % 4;
00183       if (i != 0)
00184          siz = (4 - i);
00185       return (curr + siz + 13 + (high-low+1)*4);
00186    }   
00187    public void offsetToPointer(ByteCode bc) {
00188       int i;
00189       default_inst = bc.locateInst(default_offset+label);
00190       if (default_inst==null) {
00191          System.out.println("Warning: can't locate target of instruction");
00192          System.out.println(" which should be at byte address " + (label+default_offset));
00193       } else
00194          default_inst.labelled = true;
00195       if (high-low+1>0) {
00196          jump_insts = new Instruction[high-low+1];
00197          for (i=0;i<high-low+1;i++) {
00198             jump_insts[i] = bc.locateInst(jump_offsets[i]+label);
00199             if (jump_insts[i]==null) {
00200                System.out.println("Warning: can't locate target of instruction");
00201                System.out.println(" which should be at byte address " +
00202                                   (label+jump_offsets[i]));
00203             } else
00204                jump_insts[i].labelled = true;
00205          }
00206       }
00207    }   
00208    public int parse(byte bc[],int index) {
00209       // first figure out padding to next 4-byte quantity
00210       int i,j,baseindex;
00211       baseindex = index;
00212       i = index % 4;
00213       if (i != 0)
00214          pad = (byte)(4 - i);
00215       else
00216          pad = (byte)0;
00217       index += pad;
00218       default_offset = getInt(bc,index);
00219       index += 4;
00220       low = getInt(bc,index);
00221       index += 4;
00222       high = getInt(bc,index);
00223       index += 4;
00224       i = high-low+1;
00225       if (i>0) {
00226          jump_offsets = new int[i];
00227          j = 0;
00228          do {
00229             jump_offsets[j] = getInt(bc,index);
00230             index += 4;
00231             j++;
00232          } while(j<i);
00233       }
00234       return index;
00235    }   
00236    public String toString(cp_info constant_pool[]) {
00237       String args;
00238       int i;
00239       args = super.toString(constant_pool) + argsep + "(" +
00240          Integer.toString(pad) + ")";
00241       args = args + argsep + "label_" + Integer.toString(default_inst.label);
00242       args = args + argsep + Integer.toString(low);
00243       args = args + argsep + Integer.toString(high) + ": ";
00244       for (i=0;i<high-low+1;i++) {
00245          args = args + argsep + "label_" + Integer.toString(jump_insts[i].label);
00246       }
00247       return args;
00248    }   
00249 }