Examples of org.apache.bcel.util.InstructionFinder.search()

Class org.apache.bcel.util.InstructionFinder

Examples of org.apache.bcel.util.InstructionFinder.search()

org.apache.bcel.util.InstructionFinder.search()
Search for the given pattern in the instruction list. You can search for any valid opcode via its symbolic name, e.g. "istore". You can also use a super class or an interface name to match a whole set of instructions, e.g. "BranchInstruction" or "LoadInstruction". "istore" is also an alias for all "istore_x" instructions. Additional aliases are "if" for "ifxx", "if_icmp" for "if_icmpxx", "if_acmp" for "if_acmpxx". Consecutive instruction names must be separated by white space which will be removed during the compilation of the pattern. For the rest the usual pattern matching rules for regular expressions apply.
Example pattern:
```
 search("BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*"); 
```
If you alter the instruction list upon a match such that other matching areas are affected, you should call reread() to update the finder and call search() again, because the matches are cached. @param pattern the instruction pattern to search for, where case is ignored @param from where to start the search in the instruction list @param constraint optional CodeConstraint to check the found code pattern for user-defined constraints @return iterator of matches where e.nextElement() returns an array ofinstruction handles describing the matched area

            }
  }
        
  // ILOAD_N, ILOAD_N, SWAP, ISTORE_N => ILOAD_N
  pattern = "ILOAD ILOAD SWAP ISTORE";
  for (Iterator iter = find.search(pattern); iter.hasNext();) {
            InstructionHandle[] match = (InstructionHandle[]) iter.next();
            try {              
                org.apache.bcel.generic.ILOAD iload1 = 
                    (org.apache.bcel.generic.ILOAD) match[0].getInstruction();
                org.apache.bcel.generic.ILOAD iload2 =

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            }
        }


        // LoadInstruction_N, LoadInstruction_M, SWAP => LoadInstruction_M, LoadInstruction_N
  pattern = "LoadInstruction LoadInstruction SWAP";
  for (Iterator iter = find.search(pattern); iter.hasNext();) {
            InstructionHandle[] match = (InstructionHandle[])iter.next();
            try {
                if (!match[0].hasTargeters() &&
                    !match[1].hasTargeters() &&
                    !match[2].hasTargeters())

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            }
        }
                
        // ALOAD_N ALOAD_N => ALOAD_N DUP
  pattern = "ALOAD ALOAD";
        for (Iterator iter = find.search(pattern); iter.hasNext();) {
            InstructionHandle[] match = (InstructionHandle[])iter.next();
            try {
                if (!match[1].hasTargeters()) {
                    org.apache.bcel.generic.ALOAD aload1 = 
                        (org.apache.bcel.generic.ALOAD) match[0].getInstruction();

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   */
  private static final void optimizeIFs(InstructionList il) {
    InstructionFinder f   = new InstructionFinder(il);
    String      pat = "IF_ICMP ICONST_1 GOTO ICONST_0 IFEQ Instruction";


    for(Iterator it = f.search(pat, my_constraint); it.hasNext();) {
      InstructionHandle[] match = (InstructionHandle[])it.next();
      // Everything ok, update code
      BranchInstruction ifeq    = (BranchInstruction)(match[4].getInstruction());
      BranchHandle      if_icmp = (BranchHandle)match[0];

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    InstructionFinder f     = new InstructionFinder(il);
    String            pat   = "NOP+"; // Find at least one NOP
    InstructionHandle next  = null;
    int               count = 0;


    for(Iterator e = f.search(pat); e.hasNext(); ) {
      InstructionHandle[] match = (InstructionHandle[])e.next();
      InstructionHandle   first = match[0];
      InstructionHandle   last  = match[match.length - 1];
      
      /* Some nasty Java compilers may add NOP at end of method.

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    InstructionFinder f     = new InstructionFinder(il);
    String            pat   = "NOP+"; // Find at least one NOP
    InstructionHandle next  = null;
    int               count = 0;


    for(Iterator i = f.search(pat); i.hasNext(); ) {
      InstructionHandle[] match = (InstructionHandle[])e.next();
      InstructionHandle   first = match[0];
      InstructionHandle   last  = match[match.length - 1];
      
      /* Some nasty Java compilers may add NOP at end of method.

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  InstructionHandle ih;
  String pattern;


  // Remove seqences of ALOAD, POP (GTM)
  pattern = "`ALOAD'`POP'`Instruction'";
  for(Iterator iter=find.search(pattern); iter.hasNext();){
      InstructionHandle[] match = (InstructionHandle[])iter.next();
      try {
    if ((!match[0].hasTargeters()) && (!match[1].hasTargeters())) {
                    il.delete(match[0], match[1]);
                }

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                // TODO: move target down into the list
            }
  }
  // Replace sequences of ILOAD_?, ALOAD_?, SWAP with ALOAD_?, ILOAD_?
  pattern = "`ILOAD'`ALOAD'`SWAP'`Instruction'";
  for(Iterator iter=find.search(pattern); iter.hasNext();){
            InstructionHandle[] match = (InstructionHandle[])iter.next();
            try {
                org.apache.bcel.generic.Instruction iload;
                org.apache.bcel.generic.Instruction aload;
                if ((!match[0].hasTargeters()) &&

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            }
        }
        
        // Replace sequences of ALOAD_1, ALOAD_1 with ALOAD_1, DUP 
  pattern = "`ALOAD_1'`ALOAD_1'`Instruction'";
        for(Iterator iter=find.search(pattern); iter.hasNext();){
            InstructionHandle[] match = (InstructionHandle[])iter.next();
            try {
          org.apache.bcel.generic.Instruction iload;
                org.apache.bcel.generic.Instruction aload;
                if ((!match[0].hasTargeters()) && (!match[1].hasTargeters())) {

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     */
    private void peepHoleOptimization(MethodGenerator methodGen) {
  final String pattern = "`ALOAD'`POP'`Instruction'";
  final InstructionList il = methodGen.getInstructionList();
  final InstructionFinder find = new InstructionFinder(il);
  for(Iterator iter=find.search(pattern); iter.hasNext(); ) {
      InstructionHandle[] match = (InstructionHandle[])iter.next();
      try {
    il.delete(match[0], match[1]);
      } 
      catch (TargetLostException e) {

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