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Java example source code file (relocator.hpp)

This example Java source code file (relocator.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytecodes::code, bytecodes\:\:length_at, bytes\:\:put_java_u2, null, relocator, relocatorlistener, resourceobj, share_vm_runtime_relocator_hpp, stackobj, target_arch_arm, target_arch_ppc, target_arch_x86, target_arch_zero, traps

The relocator.hpp Java example source code

/*
 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_RUNTIME_RELOCATOR_HPP
#define SHARE_VM_RUNTIME_RELOCATOR_HPP

#include "interpreter/bytecodes.hpp"
#include "oops/method.hpp"
#ifdef TARGET_ARCH_x86
# include "bytes_x86.hpp"
#endif
#ifdef TARGET_ARCH_sparc
# include "bytes_sparc.hpp"
#endif
#ifdef TARGET_ARCH_zero
# include "bytes_zero.hpp"
#endif
#ifdef TARGET_ARCH_arm
# include "bytes_arm.hpp"
#endif
#ifdef TARGET_ARCH_ppc
# include "bytes_ppc.hpp"
#endif

// This code has been converted from the 1.1E java virtual machine
// Thanks to the JavaTopics group for using the code

class ChangeItem;

// Callback object for code relocations
class RelocatorListener : public StackObj {
 public:
  RelocatorListener() {};
  virtual void relocated(int bci, int delta, int new_method_size) = 0;
};


class Relocator : public ResourceObj {
 public:
  Relocator(methodHandle method, RelocatorListener* listener);
  methodHandle insert_space_at(int bci, int space, u_char inst_buffer[], TRAPS);

  // Callbacks from ChangeItem's
  bool handle_code_changes();
  bool handle_widen       (int bci, int new_ilen, u_char inst_buffer[]);  // handles general instructions
  void push_jump_widen  (int bci, int delta, int new_delta);    // pushes jumps
  bool handle_jump_widen  (int bci, int delta);     // handles jumps
  bool handle_switch_pad  (int bci, int old_pad, bool is_lookup_switch); // handles table and lookup switches

 private:
  unsigned char* _code_array;
  int            _code_array_length;
  int            _code_length;
  unsigned char* _compressed_line_number_table;
  int            _compressed_line_number_table_size;
  methodHandle   _method;
  u_char         _overwrite[3];             // stores overwritten bytes for shrunken instructions

  GrowableArray<ChangeItem*>* _changes;

  unsigned char* code_array() const         { return _code_array; }
  void set_code_array(unsigned char* array) { _code_array = array; }

  int code_length() const                   { return _code_length; }
  void set_code_length(int length)          { _code_length = length; }

  int code_array_length() const             { return _code_array_length; }
  void set_code_array_length(int length)    { _code_array_length = length; }

  unsigned char* compressed_line_number_table() const         { return _compressed_line_number_table; }
  void set_compressed_line_number_table(unsigned char* table) { _compressed_line_number_table = table; }

  int compressed_line_number_table_size() const               { return _compressed_line_number_table_size; }
  void set_compressed_line_number_table_size(int size)        { _compressed_line_number_table_size = size; }

  methodHandle method() const               { return _method; }
  void set_method(methodHandle method)      { _method = method; }

  // This will return a raw bytecode, which is possibly rewritten.
  Bytecodes::Code code_at(int bci) const          { return (Bytecodes::Code) code_array()[bci]; }
  void code_at_put(int bci, Bytecodes::Code code) { code_array()[bci] = (char) code; }

  // get and set signed integers in the code_array
  inline int   int_at(int bci) const               { return Bytes::get_Java_u4(&code_array()[bci]); }
  inline void  int_at_put(int bci, int value)      { Bytes::put_Java_u4(&code_array()[bci], value); }

  // get and set signed shorts in the code_array
  inline short short_at(int bci) const            { return (short)Bytes::get_Java_u2(&code_array()[bci]); }
  inline void  short_at_put(int bci, short value) { Bytes::put_Java_u2((address) &code_array()[bci], value); }

  // get the address of in the code_array
  inline char* addr_at(int bci) const             { return (char*) &code_array()[bci]; }

  int  instruction_length_at(int bci)             { return Bytecodes::length_at(NULL, code_array() + bci); }

  // Helper methods
  int  align(int n) const                          { return (n+3) & ~3; }
  int  code_slop_pct() const                       { return 25; }
  bool is_opcode_lookupswitch(Bytecodes::Code bc);

  // basic relocation methods
  bool relocate_code         (int bci, int ilen, int delta);
  void change_jumps          (int break_bci, int delta);
  void change_jump           (int bci, int offset, bool is_short, int break_bci, int delta);
  void adjust_exception_table(int bci, int delta);
  void adjust_line_no_table  (int bci, int delta);
  void adjust_local_var_table(int bci, int delta);
  void adjust_stack_map_table(int bci, int delta);
  int  get_orig_switch_pad   (int bci, bool is_lookup_switch);
  int  rc_instr_len          (int bci);
  bool expand_code_array     (int delta);

  // Callback support
  RelocatorListener *_listener;
  void notify(int bci, int delta, int new_code_length) {
    if (_listener != NULL)
      _listener->relocated(bci, delta, new_code_length);
  }
};

#endif // SHARE_VM_RUNTIME_RELOCATOR_HPP

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