/** Instrument the specified method to replace mapped calls. */
  public void instrument_method(Method m, MethodGen mg) {

    // Loop through each instruction, making substitutions
    InstructionList il = mg.getInstructionList();
    for (InstructionHandle ih = il.getStart(); ih != null; ) {
      if (debug_instrument_inst.enabled()) {
        debug_instrument_inst.log("instrumenting instruction %s%n", ih);
        // ih.getInstruction().toString(pool.getConstantPool()));
      }
      InstructionList new_il = null;

      // Remember the next instruction to process
      InstructionHandle next_ih = ih.getNext();

      // Get the translation for this instruction (if any)
      new_il = xform_inst(mg, ih.getInstruction());
      if (debug_instrument_inst.enabled()) debug_instrument_inst.log("  new inst: %s%n", new_il);

      // If this instruction was modified, replace it with the new
      // instruction list. If this instruction was the target of any
      // jumps or line numbers , replace them with the first
      // instruction in the new list
      replace_instructions(il, ih, new_il);

      ih = next_ih;
    }
  }
 /** Dumps out the map list to the debug_map logger * */
 public static void dump_map_list() {
   if (debug_map.enabled()) {
     for (MethodMapInfo mmi : map_list) {
       debug_map.log("Class re '%s': %n", mmi.class_regex);
       for (MethodDef md : mmi.map.keySet()) {
         MethodInfo mi = mmi.map.get(md);
         debug_map.log("  %s - %s [%d replacements]%n", md, mi.method_class, mi.cnt);
       }
     }
   }
 }
  /**
   * Transforms invoke instructions that match the specified list for this class to call the
   * specified static call instead.
   */
  private InstructionList xform_inst(MethodGen mg, Instruction inst) {

    switch (inst.getOpcode()) {
      case Constants.INVOKESTATIC:
        {
          InstructionList il = new InstructionList();
          INVOKESTATIC is = (INVOKESTATIC) inst;
          String cname = is.getClassName(pgen);
          String mname = is.getMethodName(pgen);
          Type[] args = is.getArgumentTypes(pgen);
          MethodDef orig = new MethodDef(cname + "." + mname, args);
          MethodInfo call = method_map.get(orig);
          if (call != null) {
            call.cnt++;
            String classname = call.method_class;
            String methodname = mname;
            debug_map.log(
                "%s.%s: Replacing method %s.%s (%s) with %s.%s%n",
                mg.getClassName(),
                mg.getName(),
                cname,
                mname,
                UtilMDE.join(args, ", "),
                classname,
                methodname);
            il.append(
                ifact.createInvoke(
                    classname, methodname, is.getReturnType(pgen), args, Constants.INVOKESTATIC));
          }
          return (il);
        }

      case Constants.INVOKEVIRTUAL:
        {
          InstructionList il = new InstructionList();
          INVOKEVIRTUAL iv = (INVOKEVIRTUAL) inst;
          String cname = iv.getClassName(pgen);
          String mname = iv.getMethodName(pgen);
          Type[] args = iv.getArgumentTypes(pgen);
          Type instance_type = iv.getReferenceType(pgen);
          Type[] new_args = BCELUtil.insert_type(instance_type, args);
          MethodDef orig = new MethodDef(cname + "." + mname, args);
          if (debug_class) System.out.printf("looking for %s in map %s%n", orig, method_map);
          MethodInfo call = method_map.get(orig);
          if (call != null) {
            call.cnt++;
            String classname = call.method_class;
            String methodname = mname;
            debug_map.log(
                "Replacing method %s.%s (%s) with %s.%s%n",
                cname, mname, ArraysMDE.toString(args), classname, methodname);
            il.append(
                ifact.createInvoke(
                    classname,
                    methodname,
                    iv.getReturnType(pgen),
                    new_args,
                    Constants.INVOKESTATIC));
          }
          return (il);
        }

      default:
        return (null);
    }
  }
  /**
   * Given another class, return a transformed version of the class which replaces specified calls
   * with alternative static implementations
   */
  public byte[] transform(
      ClassLoader loader,
      String className,
      Class<?> classBeingRedefined,
      ProtectionDomain protectionDomain,
      byte[] classfileBuffer)
      throws IllegalClassFormatException {

    // debug = className.equals ("chicory/Test");

    String fullClassName = className.replace("/", ".");

    debug_transform.log("In Transform: class = %s%n", className);

    // Don't instrument boot classes.  We only want to instrument
    // user classes classpath.
    // Most boot classes have the null loader,
    // but some generated classes (such as those in sun.reflect) will
    // have a non-null loader.  Some of these have a null parent loader,
    // but some do not.  The check for the sun.reflect package is a hack
    // to catch all of these.  A more consistent mechanism to determine
    // boot classes would be preferrable.
    if (loader == null) {
      debug_transform.log("ignoring system class %s, class loader == null", fullClassName);
      return (null);
    } else if (loader.getParent() == null) {
      debug_transform.log("ignoring system class %s, parent loader == null\n", fullClassName);
      return (null);
    } else if (fullClassName.startsWith("sun.reflect")) {
      debug_transform.log("ignoring system class %s, in sun.reflect package", fullClassName);
      return (null);
    } else if (fullClassName.startsWith("com.sun")) {
      System.out.printf("Class from com.sun package %s with nonnull loaders\n", fullClassName);
    }

    // Don't intrument our code
    if (className.startsWith("randoop.")) {
      debug_transform.log("Not considering randoop class %s%n", fullClassName);
      return (null);
    }

    // Look for match with specified regular expressions for class
    method_map = null;
    debug_class = false;
    for (MethodMapInfo mmi : map_list) {
      if (mmi.class_regex.matcher(className).matches()) {
        if (false && className.startsWith("RandoopTest")) debug_class = true;
        if (debug_class)
          System.out.printf("Classname %s matches re %s%n", className, mmi.class_regex);
        method_map = mmi.map;
        break;
      }
    }
    if (method_map == null) return null;

    debug_transform.log(
        "transforming class %s, loader %s - %s%n", className, loader, loader.getParent());

    // Parse the bytes of the classfile, die on any errors
    JavaClass c = null;
    ClassParser parser = new ClassParser(new ByteArrayInputStream(classfileBuffer), className);
    try {
      c = parser.parse();
    } catch (Exception e) {
      throw new RuntimeException("Unexpected error", e);
    }

    try {
      // Get the class information
      ClassGen cg = new ClassGen(c);
      ifact = new InstructionFactory(cg);

      map_calls(cg, className, loader);

      JavaClass njc = cg.getJavaClass();
      if (debug) njc.dump("/tmp/ret/" + njc.getClassName() + ".class");

      if (true) {
        return (cg.getJavaClass().getBytes());
      } else {
        debug_transform.log("not including class %s (filtered out)", className);
        return null;
      }

    } catch (Throwable e) {
      out.format("Unexpected error %s in transform", e);
      e.printStackTrace();
      return (null);
    }
  }