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    1   package org.apache.bcel.util;
    2
    3   /* ====================================================================
    4    * The Apache Software License, Version 1.1
    5    *
    6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
    7    * reserved.
    8    *
    9    * Redistribution and use in source and binary forms, with or without
    10   * modification, are permitted provided that the following conditions
    11   * are met:
    12   *
    13   * 1. Redistributions of source code must retain the above copyright
    14   *    notice, this list of conditions and the following disclaimer.
    15   *
    16   * 2. Redistributions in binary form must reproduce the above copyright
    17   *    notice, this list of conditions and the following disclaimer in
    18   *    the documentation and/or other materials provided with the
    19   *    distribution.
    20   *
    21   * 3. The end-user documentation included with the redistribution,
    22   *    if any, must include the following acknowledgment:
    23   *       "This product includes software developed by the
    24   *        Apache Software Foundation (http://www.apache.org/)."
    25   *    Alternately, this acknowledgment may appear in the software itself,
    26   *    if and wherever such third-party acknowledgments normally appear.
    27   *
    28   * 4. The names "Apache" and "Apache Software Foundation" and
    29   *    "Apache BCEL" must not be used to endorse or promote products
    30   *    derived from this software without prior written permission. For
    31   *    written permission, please contact apache@apache.org.
    32   *
    33   * 5. Products derived from this software may not be called "Apache",
    34   *    "Apache BCEL", nor may "Apache" appear in their name, without
    35   *    prior written permission of the Apache Software Foundation.
    36   *
    37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
    38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
    41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
    44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    48   * SUCH DAMAGE.
    49   * ====================================================================
    50   *
    51   * This software consists of voluntary contributions made by many
    52   * individuals on behalf of the Apache Software Foundation.  For more
    53   * information on the Apache Software Foundation, please see
    54   * <http://www.apache.org/>;.
    55   */
    56
    57  import java.util.*;
    58  import org.apache.bcel.Constants;
    59  import org.apache.bcel.generic.*;
    60  import org.apache.regexp.*;
    61
    62  /***
    63   * InstructionFinder is a tool to search for given instructions patterns,
    64   * i.e., match sequences of instructions in an instruction list via
    65   * regular expressions. This can be used, e.g., in order to implement
    66   * a peep hole optimizer that looks for code patterns and replaces
    67   * them with faster equivalents.
    68   *
    69   * <p>This class internally uses the <a href="http://jakarta.apache.org/regexp/">
    70   * Regexp</a> package to search for regular expressions.
    71   *
    72   * A typical application would look like this:
    73  <pre>
    74      InstructionFinder f   = new InstructionFinder(il);
    75      String            pat = "IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)";
    76
    77      for(Iterator i = f.search(pat, constraint); i.hasNext(); ) {
    78        InstructionHandle[] match = (InstructionHandle[])i.next();
    79        ...
    80        il.delete(match[1], match[5]);
    81        ...
    82      }
    83  </pre>
    84   * @version $Id: InstructionFinder.java,v 1.1.1.1 2001/10/29 20:00:30 jvanzyl Exp $
    85   * @author  <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A>
    86   * @see Instruction
    87   * @see InstructionList
    88   */
    89  public class InstructionFinder {
    90    private static final int OFFSET     = 32767; // char + OFFSET is outside of LATIN-1
    91    private static final int NO_OPCODES = 256;   // Potential number, some are not used
    92
    93    private static final HashMap map = new HashMap(); // Map<String,Pattern>
    94
    95    private InstructionList     il;
    96    private String              il_string;    // instruction list as string
    97    private InstructionHandle[] handles;      // map instruction list to array
    98
    99    /***
    100    * @param il instruction list to search for given patterns
    101    */
    102   public InstructionFinder(InstructionList il) {
    103     this.il = il;
    104     reread();
    105   }
    106
    107   /***
    108    * Reread the instruction list, e.g., after you've altered the list upon a match.
    109    */
    110   public final void reread() {
    111     int    size  = il.getLength();
    112     char[] buf   = new char[size]; // Create a string with length equal to il length
    113     handles      = il.getInstructionHandles();
    114
    115     // Map opcodes to characters
    116     for(int i=0; i < size; i++)
    117       buf[i] = makeChar(handles[i].getInstruction().getOpcode());
    118
    119     il_string = new String(buf);
    120   }
    121
    122   /***
    123    * Map symbolic instruction names like "getfield" to a single character.
    124    *
    125    * @param pattern instruction pattern in lower case
    126    * @return encoded string for a pattern such as "BranchInstruction".
    127    */
    128   private static final String mapName(String pattern) {
    129     String result = (String)map.get(pattern);
    130
    131     if(result != null)
    132       return result;
    133
    134     for(short i=0; i < NO_OPCODES; i++)
    135       if(pattern.equals(Constants.OPCODE_NAMES[i]))
    136 	return "" + makeChar(i);
    137
    138     throw new RuntimeException("Instruction unknown: " + pattern);
    139   }
    140
    141   /***
    142    * Replace symbolic names of instructions with the appropiate character and remove
    143    * all white space from string. Meta characters such as +, * are ignored.
    144    *
    145    * @param pattern The pattern to compile
    146    * @return translated regular expression string
    147    */
    148   private static final String compilePattern(String pattern) {
    149     String       lower      = pattern.toLowerCase();
    150     StringBuffer buf        = new StringBuffer();
    151     int          size       = pattern.length();
    152
    153     for(int i=0; i < size; i++) {
    154       char ch = lower.charAt(i);
    155
    156       if(Character.isLetterOrDigit(ch)) {
    157 	StringBuffer name = new StringBuffer();
    158
    159 	while((Character.isLetterOrDigit(ch) || ch == '_') && i < size) {
    160 	  name.append(ch);
    161
    162 	  if(++i < size)
    163 	    ch = lower.charAt(i);
    164 	  else
    165 	    break;
    166 	}
    167
    168 	i--;
    169
    170 	buf.append(mapName(name.toString()));
    171       } else if(!Character.isWhitespace(ch))
    172 	buf.append(ch);
    173     }
    174
    175     return buf.toString();
    176   }
    177
    178   /***
    179    * @return the matched piece of code as an array of instruction (handles)
    180    */
    181   private InstructionHandle[] getMatch(int matched_from, int match_length) {
    182     InstructionHandle[] match = new InstructionHandle[match_length];
    183     System.arraycopy(handles, matched_from, match, 0, match_length);
    184
    185     return match;
    186   }
    187
    188   /***
    189    * Search for the given pattern in the instruction list. You can search for any valid
    190    * opcode via its symbolic name, e.g. "istore". You can also use a super class or
    191    * an interface name to match a whole set of instructions, e.g. "BranchInstruction" or
    192    * "LoadInstruction". "istore" is also an alias for all "istore_x" instructions. Additional
    193    * aliases are "if" for "ifxx", "if_icmp" for "if_icmpxx", "if_acmp" for "if_acmpxx".
    194    *
    195    * Consecutive instruction names must be separated by white space which will be removed
    196    * during the compilation of the pattern.
    197    *
    198    * For the rest the usual pattern matching rules for regular expressions apply.<P>
    199    * Example pattern:
    200    * <pre>
    201      search("BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*");
    202    * </pre>
    203    *
    204    * <p>If you alter the instruction list upon a match such that other
    205    * matching areas are affected, you should call reread() to update
    206    * the finder and call search() again, because the matches are cached.
    207    *
    208    * @param pattern the instruction pattern to search for, where case is ignored
    209    * @param from where to start the search in the instruction list
    210    * @param constraint optional CodeConstraint to check the found code pattern for
    211    * user-defined constraints
    212    * @return iterator of matches where e.nextElement() returns an array of instruction handles
    213    * describing the matched area
    214    */
    215   public final Iterator search(String pattern, InstructionHandle from,
    216 			       CodeConstraint constraint)
    217   {
    218     String search = compilePattern(pattern);
    219     int  start    = -1;
    220
    221     for(int i=0; i < handles.length; i++) {
    222       if(handles[i] == from) {
    223 	start = i; // Where to start search from (index)
    224 	break;
    225       }
    226     }
    227
    228     if(start == -1)
    229       throw new ClassGenException("Instruction handle " + from +
    230 				  " not found in instruction list.");
    231     try {
    232       RE regex = new RE(search);
    233       ArrayList matches = new ArrayList();
    234
    235       while(start < il_string.length() && regex.match(il_string, start)) {
    236 	int startExpr = regex.getParenStart(0);
    237 	int endExpr   = regex.getParenEnd(0);
    238 	int lenExpr   = regex.getParenLength(0);
    239
    240 	InstructionHandle[] match = getMatch(startExpr, lenExpr);
    241
    242 	if((constraint == null) || constraint.checkCode(match))
    243 	  matches.add(match);
    244 	start = endExpr;
    245       }
    246
    247       return matches.iterator();
    248     } catch(RESyntaxException e) {
    249       System.err.println(e);
    250     }
    251
    252     return null;
    253   }
    254
    255   /***
    256    * Start search beginning from the start of the given instruction list.
    257    *
    258    * @param pattern the instruction pattern to search for, where case is ignored
    259    * @return iterator of matches where e.nextElement()
    260    * returns an array of instruction handles describing the matched
    261    * area
    262    */
    263   public final Iterator search(String pattern) {
    264     return search(pattern, il.getStart(), null);
    265   }
    266
    267   /***
    268    * Start search beginning from `from'.
    269    *
    270    * @param pattern the instruction pattern to search for, where case is ignored
    271    * @param from where to start the search in the instruction list
    272    * @return  iterator of matches where e.nextElement() returns an array of instruction handles
    273    * describing the matched area
    274    */
    275   public final Iterator search(String pattern, InstructionHandle from) {
    276     return search(pattern, from, null);
    277   }
    278
    279   /***
    280    * Start search beginning from the start of the given instruction list.
    281    * Check found matches with the constraint object.
    282    *
    283    * @param pattern the instruction pattern to search for, case is ignored
    284    * @param constraint constraints to be checked on matching code
    285    * @return instruction handle or `null' if the match failed
    286    */
    287   public final Iterator search(String pattern, CodeConstraint constraint) {
    288     return search(pattern, il.getStart(), constraint);
    289   }
    290
    291   /***
    292    * Convert opcode number to char.
    293    */
    294   private static final char makeChar(short opcode) {
    295     return (char)(opcode + OFFSET);
    296   }
    297
    298   /***
    299    * @return the inquired instruction list
    300    */
    301   public final InstructionList getInstructionList() { return il; }
    302
    303   /***
    304    * Code patterns found may be checked using an additional
    305    * user-defined constraint object whether they really match the needed criterion.
    306    * I.e., check constraints that can not expressed with regular expressions.
    307    *
    308    */
    309   public interface CodeConstraint {
    310     /***
    311      * @param match array of instructions matching the requested pattern
    312      * @return true if the matched area is really useful
    313      */
    314     public boolean checkCode(InstructionHandle[] match);
    315   }
    316
    317   // Initialize pattern map
    318
    319   static {
    320     map.put("arithmeticinstruction", "(irem|lrem|iand|ior|ineg|isub|lneg|fneg|fmul|ldiv|fadd|lxor|frem|idiv|land|ixor|ishr|fsub|lshl|fdiv|iadd|lor|dmul|lsub|ishl|imul|lmul|lushr|dneg|iushr|lshr|ddiv|drem|dadd|ladd|dsub)");
    321     map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial)");
    322     map.put("arrayinstruction", "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)");
    323     map.put("gotoinstruction", "(goto|goto_w)");
    324     map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)");
    325     map.put("localvariableinstruction", "(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)");
    326     map.put("loadinstruction", "(fload|dload|lload|iload|aload)");
    327     map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)");
    328     map.put("cpinstruction", "(ldc2_w|invokeinterface|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)");
    329     map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)");
    330     map.put("branchinstruction", "(ifle|if_acmpne|if_icmpeq|if_acmpeq|ifnonnull|goto_w|iflt|ifnull|if_icmpne|tableswitch|if_icmple|ifeq|if_icmplt|jsr_w|if_icmpgt|ifgt|jsr|goto|ifne|ifge|lookupswitch|if_icmpge)");
    331     map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)");
    332     map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)");
    333     map.put("select", "(tableswitch|lookupswitch)");
    334     map.put("ifinstruction", "(ifeq|ifgt|if_icmpne|if_icmpeq|ifge|ifnull|ifne|if_icmple|if_icmpge|if_acmpeq|if_icmplt|if_acmpne|ifnonnull|iflt|if_icmpgt|ifle)");
    335     map.put("jsrinstruction", "(jsr|jsr_w)");
    336     map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)");
    337     map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)");
    338     map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)");
    339     map.put("typedinstruction", "(imul|lsub|aload|fload|lor|new|aaload|fcmpg|iand|iaload|lrem|idiv|d2l|isub|dcmpg|dastore|ret|f2d|f2i|drem|iinc|i2c|checkcast|frem|lreturn|astore|lushr|daload|dneg|fastore|istore|lshl|ldiv|lstore|areturn|ishr|ldc_w|invokeinterface|aastore|lxor|ishl|l2d|i2f|return|faload|sipush|iushr|caload|instanceof|invokespecial|putfield|fmul|ireturn|laload|d2f|lneg|ixor|i2l|fdiv|lastore|multianewarray|i2b|getstatic|i2d|putstatic|fcmpl|saload|ladd|irem|dload|jsr_w|dconst|dcmpl|fsub|freturn|ldc|aconst_null|castore|lmul|ldc2_w|dadd|iconst|f2l|ddiv|dstore|land|jsr|anewarray|dmul|bipush|dsub|sastore|d2i|i2s|lshr|iadd|l2i|lload|bastore|fstore|fneg|iload|fadd|baload|fconst|ior|ineg|dreturn|l2f|lconst|getfield|invokevirtual|invokestatic|iastore)");
    340     map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)");
    341     map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)");
    342     map.put("indexedinstruction", "(lload|lstore|fload|ldc2_w|invokeinterface|multianewarray|astore|dload|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|dstore|istore|iinc|ldc_w|ret|fstore|invokestatic|iload|putfield|invokevirtual|ldc|new|aload|anewarray)");
    343     map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)");
    344     map.put("stackproducer", "(imul|lsub|aload|fload|lor|new|aaload|fcmpg|iand|iaload|lrem|idiv|d2l|isub|dcmpg|dup|f2d|f2i|drem|i2c|checkcast|frem|lushr|daload|dneg|lshl|ldiv|ishr|ldc_w|invokeinterface|lxor|ishl|l2d|i2f|faload|sipush|iushr|caload|instanceof|invokespecial|fmul|laload|d2f|lneg|ixor|i2l|fdiv|getstatic|i2b|swap|i2d|dup2|fcmpl|saload|ladd|irem|dload|jsr_w|dconst|dcmpl|fsub|ldc|arraylength|aconst_null|tableswitch|lmul|ldc2_w|iconst|dadd|f2l|ddiv|land|jsr|anewarray|dmul|bipush|dsub|d2i|newarray|i2s|lshr|iadd|lload|l2i|fneg|iload|fadd|baload|fconst|lookupswitch|ior|ineg|lconst|l2f|getfield|invokevirtual|invokestatic)");
    345     map.put("stackconsumer", "(imul|lsub|lor|iflt|fcmpg|if_icmpgt|iand|ifeq|if_icmplt|lrem|ifnonnull|idiv|d2l|isub|dcmpg|dastore|if_icmpeq|f2d|f2i|drem|i2c|checkcast|frem|lreturn|astore|lushr|pop2|monitorexit|dneg|fastore|istore|lshl|ldiv|lstore|areturn|if_icmpge|ishr|monitorenter|invokeinterface|aastore|lxor|ishl|l2d|i2f|return|iushr|instanceof|invokespecial|fmul|ireturn|d2f|lneg|ixor|pop|i2l|ifnull|fdiv|lastore|i2b|if_acmpeq|ifge|swap|i2d|putstatic|fcmpl|ladd|irem|dcmpl|fsub|freturn|ifgt|castore|lmul|dadd|f2l|ddiv|dstore|land|if_icmpne|if_acmpne|dmul|dsub|sastore|ifle|d2i|i2s|lshr|iadd|l2i|bastore|fstore|fneg|fadd|ior|ineg|ifne|dreturn|l2f|if_icmple|getfield|invokevirtual|invokestatic|iastore)");
    346     map.put("exceptionthrower", "(irem|lrem|laload|putstatic|baload|dastore|areturn|getstatic|ldiv|anewarray|iastore|castore|idiv|saload|lastore|fastore|putfield|lreturn|caload|getfield|return|aastore|freturn|newarray|instanceof|multianewarray|athrow|faload|iaload|aaload|dreturn|monitorenter|checkcast|bastore|arraylength|new|invokevirtual|sastore|ldc_w|ireturn|invokespecial|monitorexit|invokeinterface|ldc|invokestatic|daload)");
    347     map.put("loadclass", "(multianewarray|invokeinterface|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)");
    348     map.put("instructiontargeter", "(ifle|if_acmpne|if_icmpeq|if_acmpeq|ifnonnull|goto_w|iflt|ifnull|if_icmpne|tableswitch|if_icmple|ifeq|if_icmplt|jsr_w|if_icmpgt|ifgt|jsr|goto|ifne|ifge|lookupswitch|if_icmpge)");
    349
    350     // Some aliases
    351     map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)");
    352     map.put("if_acmp", "(if_acmpeq|if_acmpne)");
    353     map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)");
    354
    355     // Precompile some aliases first
    356     map.put("iconst", precompile(Constants.ICONST_0, Constants.ICONST_5, Constants.ICONST_M1));
    357     map.put("lconst", new String(new char[] { '(', makeChar(Constants.LCONST_0), '|',
    358 					      makeChar(Constants.LCONST_1), ')' }));
    359     map.put("dconst", new String(new char[] { '(', makeChar(Constants.DCONST_0), '|',
    360 					      makeChar(Constants.DCONST_1), ')' }));
    361     map.put("fconst", new String(new char[] { '(', makeChar(Constants.FCONST_0), '|',
    362 					      makeChar(Constants.FCONST_1), ')' }));
    363
    364     map.put("iload", precompile(Constants.ILOAD_0, Constants.ILOAD_3, Constants.ILOAD));
    365     map.put("dload", precompile(Constants.DLOAD_0, Constants.DLOAD_3, Constants.DLOAD));
    366     map.put("fload", precompile(Constants.FLOAD_0, Constants.FLOAD_3, Constants.FLOAD));
    367     map.put("aload", precompile(Constants.ALOAD_0, Constants.ALOAD_3, Constants.ALOAD));
    368
    369     map.put("istore", precompile(Constants.ISTORE_0, Constants.ISTORE_3, Constants.ISTORE));
    370     map.put("dstore", precompile(Constants.DSTORE_0, Constants.DSTORE_3, Constants.DSTORE));
    371     map.put("fstore", precompile(Constants.FSTORE_0, Constants.FSTORE_3, Constants.FSTORE));
    372     map.put("astore", precompile(Constants.ASTORE_0, Constants.ASTORE_3, Constants.ASTORE));
    373
    374     // Compile strings
    375
    376     for(Iterator i = map.keySet().iterator(); i.hasNext(); ) {
    377       String key   = (String)i.next();
    378       String value = (String)map.get(key);
    379
    380       char ch = value.charAt(1); // Omit already precompiled patterns
    381       if(ch < OFFSET) {
    382 	map.put(key, compilePattern(value)); // precompile all patterns
    383       }
    384     }
    385
    386     // Add instruction alias to match anything
    387
    388     StringBuffer buf = new StringBuffer("(");
    389
    390     for(short i=0; i < NO_OPCODES; i++) {
    391       if(Constants.NO_OF_OPERANDS[i] != Constants.UNDEFINED) { // Not an invalid opcode
    392 	buf.append(makeChar(i));
    393
    394 	if(i < NO_OPCODES - 1)
    395 	  buf.append('|');
    396       }
    397     }
    398     buf.append(')');
    399
    400     map.put("instruction", buf.toString());
    401   }
    402
    403   private static String precompile(short from, short to, short extra) {
    404     StringBuffer buf = new StringBuffer("(");
    405
    406     for(short i=from; i <= to; i++) {
    407       buf.append(makeChar(i));
    408       buf.append('|');
    409     }
    410
    411     buf.append(makeChar(extra));
    412     buf.append(")");
    413     return buf.toString();
    414   }
    415
    416   /*
    417    * Internal debugging routines.
    418    */
    419   private static final String pattern2string(String pattern) {
    420     return pattern2string(pattern, true);
    421   }
    422
    423   private static final String pattern2string(String pattern, boolean make_string) {
    424     StringBuffer buf = new StringBuffer();
    425
    426     for(int i=0; i < pattern.length(); i++) {
    427       char ch = pattern.charAt(i);
    428
    429       if(ch >= OFFSET) {
    430 	if(make_string)
    431 	  buf.append(Constants.OPCODE_NAMES[ch - OFFSET]);
    432 	else
    433 	  buf.append((int)(ch - OFFSET));
    434       } else
    435 	buf.append(ch);
    436     }
    437
    438     return buf.toString();
    439   }
    440 }

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