/*

 * Copyright (c) 1997, 2005, 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.

 *

 */

# include "incls/_precompiled.incl"

# include "incls/_relocator.cpp.incl"

#define MAX_METHOD_LENGTH  65535

#define MAX_SHORT ((1 << 15) - 1)

#define MIN_SHORT (- (1 << 15))

// Encapsulates a code change request. There are 3 types.

// General instruction, jump instruction, and table/lookup switches

//

class ChangeItem : public ResourceObj {

  int _bci;

 public:

   ChangeItem(int bci) { _bci = bci; }

   virtual bool handle_code_change(Relocator *r) = 0;

   // type info

   virtual bool is_widen()      { return false; }

   virtual bool is_jump_widen() { return false; }

   virtual bool is_switch_pad() { return false; }

   // accessors

   int bci()    { return _bci; }

   void relocate(int break_bci, int delta) { if (_bci > break_bci) { _bci += delta; } }

   virtual bool adjust(int bci, int delta) { return false; }

   // debug

   virtual void print() = 0;

};

class ChangeWiden : public ChangeItem {

  int              _new_ilen;    // New length of instruction at bci

  u_char*          _inst_buffer; // New bytecodes

 public:

  ChangeWiden(int bci, int new_ilen, u_char* inst_buffer) : ChangeItem(bci) {

    _new_ilen = new_ilen;

    _inst_buffer = inst_buffer;

  }

  // Callback to do instruction

  bool handle_code_change(Relocator *r) { return r->handle_widen(bci(), _new_ilen, _inst_buffer); };

  bool is_widen()              { return true; }

  void print()                 { tty->print_cr("ChangeWiden. bci: %d   New_ilen: %d", bci(), _new_ilen); }

};

class ChangeJumpWiden : public ChangeItem {

  int _delta;  // New length of instruction at bci

 public:

  ChangeJumpWiden(int bci, int delta) : ChangeItem(bci) { _delta = delta; }

  // Callback to do instruction

  bool handle_code_change(Relocator *r) { return r->handle_jump_widen(bci(), _delta); };

  bool is_jump_widen()         { return true; }

  // If the bci matches, adjust the delta in the change jump request.

  bool adjust(int jump_bci, int delta) {

    if (bci() == jump_bci) {

      if (_delta > 0)

        _delta += delta;

      else

        _delta -= delta;

      return true;

    }

    return false;

  }

  void print()                 { tty->print_cr("ChangeJumpWiden. bci: %d   Delta: %d", bci(), _delta); }

};

class ChangeSwitchPad : public ChangeItem {

  int  _padding;

  bool _is_lookup_switch;

 public:

   ChangeSwitchPad(int bci, int padding, bool is_lookup_switch) : ChangeItem(bci) {

     _padding = padding;

     _is_lookup_switch = is_lookup_switch;

   }

   // Callback to do instruction

   bool handle_code_change(Relocator *r) { return r->handle_switch_pad(bci(), _padding, _is_lookup_switch); };

   bool is_switch_pad()        { return true; }

   int  padding()              { return _padding;  }

   bool is_lookup_switch()     { return _is_lookup_switch; }

   void print()                { tty->print_cr("ChangeSwitchPad. bci: %d   Padding: %d  IsLookupSwitch: %d", bci(), _padding, _is_lookup_switch); }

};

//-----------------------------------------------------------------------------------------------------------

// Relocator code

Relocator::Relocator(methodHandle m, RelocatorListener* listener) {

  set_method(m);

  set_code_length(method()->code_size());

  set_code_array(NULL);

  // Allocate code array and copy bytecodes

  if (!expand_code_array(0)) {

    // Should have at least MAX_METHOD_LENGTH available or the verifier

    // would have failed.

    ShouldNotReachHere();

  }

  set_compressed_line_number_table(NULL);

  set_compressed_line_number_table_size(0);

  _listener = listener;

}

// size is the new size of the instruction at bci. Hence, if size is less than the current

// instruction sice, we will shrink the code.

methodHandle Relocator::insert_space_at(int bci, int size, u_char inst_buffer[], TRAPS) {

  _changes = new GrowableArray<ChangeItem*> (10);

  _changes->push(new ChangeWiden(bci, size, inst_buffer));

  if (TraceRelocator) {

    tty->print_cr("Space at: %d Size: %d", bci, size);

    _method->print();

    _method->print_codes();

    tty->print_cr("-------------------------------------------------");

  }

  if (!handle_code_changes()) return methodHandle();

    // Construct the new method

  methodHandle new_method = methodOopDesc::clone_with_new_data(method(),

                              code_array(), code_length(),

                              compressed_line_number_table(),

                              compressed_line_number_table_size(),

                              CHECK_(methodHandle()));

    set_method(new_method);

  if (TraceRelocator) {

    tty->print_cr("-------------------------------------------------");

    tty->print_cr("new method");

    _method->print_codes();

  }

  return new_method;

}

bool Relocator::handle_code_changes() {

  assert(_changes != NULL, "changes vector must be initialized");

  while (!_changes->is_empty()) {

    // Inv: everything is aligned.

    ChangeItem* ci = _changes->first();

    if (TraceRelocator) {

      ci->print();

    }

    // Execute operation

    if (!ci->handle_code_change(this)) return false;

    // Shuffel items up

    for (int index = 1; index < _changes->length(); index++) {

      _changes->at_put(index-1, _changes->at(index));

    }

    _changes->pop();

  }

  return true;

}

bool Relocator::is_opcode_lookupswitch(Bytecodes::Code bc) {

  switch (bc) {

    case Bytecodes::_tableswitch:       return false;

    case Bytecodes::_lookupswitch:                   // not rewritten on ia64

    case Bytecodes::_fast_linearswitch:              // rewritten _lookupswitch

    case Bytecodes::_fast_binaryswitch: return true; // rewritten _lookupswitch

    default: ShouldNotReachHere();

  }

  return true; // dummy

}

// We need a special instruction size method, since lookupswitches and tableswitches might not be

// properly alligned during relocation

int Relocator::rc_instr_len(int bci) {

  Bytecodes::Code bc= code_at(bci);

  switch (bc) {

    // In the case of switch instructions, see if we have the original

    // padding recorded.

    case Bytecodes::_tableswitch:

    case Bytecodes::_lookupswitch:

    case Bytecodes::_fast_linearswitch:

    case Bytecodes::_fast_binaryswitch:

    {

      int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc));

      if (pad == -1) {

        return instruction_length_at(bci);

      }

      // Otherwise, depends on the switch type.

      switch (bc) {

        case Bytecodes::_tableswitch: {

          int lo = int_at(bci + 1 + pad + 4 * 1);

          int hi = int_at(bci + 1 + pad + 4 * 2);

          int n = hi - lo + 1;

          return 1 + pad + 4*(3 + n);

        }

        case Bytecodes::_lookupswitch:

        case Bytecodes::_fast_linearswitch:

        case Bytecodes::_fast_binaryswitch: {

          int npairs = int_at(bci + 1 + pad + 4 * 1);

          return 1 + pad + 4*(2 + 2*npairs);

        }

        default:

          ShouldNotReachHere();

      }

    }

  }

  return instruction_length_at(bci);

}

// If a change item is recorded for "pc", with type "ct", returns the

// associated padding, else -1.

int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) {

  for (int k = 0; k < _changes->length(); k++) {

    ChangeItem* ci = _changes->at(k);

    if (ci->is_switch_pad()) {

      ChangeSwitchPad* csp = (ChangeSwitchPad*)ci;

      if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) {

        return csp->padding();

      }

    }

  }

  return -1;

}

// Push a ChangeJumpWiden if it doesn't already exist on the work queue,

// otherwise adjust the item already there by delta.  The calculation for

// new_delta is wrong for this because it uses the offset stored in the

// code stream itself which wasn't fixed when item was pushed on the work queue.

void Relocator::push_jump_widen(int bci, int delta, int new_delta) {

  for (int j = 0; j < _changes->length(); j++) {

    ChangeItem* ci = _changes->at(j);

    if (ci->adjust(bci, delta)) return;

  }

  _changes->push(new ChangeJumpWiden(bci, new_delta));

}

// The current instruction of "c" is a jump; one of its offset starts

// at "offset" and is a short if "isShort" is "TRUE",

// and an integer otherwise.  If the jump crosses "breakPC", change

// the span of the jump by "delta".

void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) {

  int bci_delta = (is_short) ? short_at(offset) : int_at(offset);

  int targ = bci + bci_delta;

  if ((bci <= break_bci && targ >  break_bci) ||

      (bci >  break_bci && targ <= break_bci)) {

    int new_delta;

    if (bci_delta > 0)

      new_delta = bci_delta + delta;

    else

      new_delta = bci_delta - delta;

    if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) {

      push_jump_widen(bci, delta, new_delta);

    } else if (is_short) {

      short_at_put(offset, new_delta);

    } else {

      int_at_put(offset, new_delta);

    }

  }

}

// Changes all jumps crossing "break_bci" by "delta".  May enqueue things

// on "rc->changes"

void Relocator::change_jumps(int break_bci, int delta) {

  int bci = 0;

  Bytecodes::Code bc;

  // Now, adjust any affected instructions.

  while (bci < code_length()) {

    switch (bc= code_at(bci)) {

      case Bytecodes::_ifeq:

      case Bytecodes::_ifne:

      case Bytecodes::_iflt:

      case Bytecodes::_ifge:

      case Bytecodes::_ifgt:

      case Bytecodes::_ifle:

      case Bytecodes::_if_icmpeq:

      case Bytecodes::_if_icmpne:

      case Bytecodes::_if_icmplt:

      case Bytecodes::_if_icmpge:

      case Bytecodes::_if_icmpgt:

      case Bytecodes::_if_icmple:

      case Bytecodes::_if_acmpeq:

      case Bytecodes::_if_acmpne:

      case Bytecodes::_ifnull:

      case Bytecodes::_ifnonnull:

      case Bytecodes::_goto:

      case Bytecodes::_jsr:

        change_jump(bci, bci+1, true, break_bci, delta);

        break;

      case Bytecodes::_goto_w:

      case Bytecodes::_jsr_w:

        change_jump(bci, bci+1, false, break_bci, delta);

        break;

      case Bytecodes::_tableswitch:

      case Bytecodes::_lookupswitch:

      case Bytecodes::_fast_linearswitch:

      case Bytecodes::_fast_binaryswitch: {

        int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch));

        int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1);

        if (bci > break_bci) {

          int new_bci = bci + delta;

          int newPad = align(new_bci+1) - (new_bci+1);

          // Do we need to check the padding?

          if (newPad != oldPad) {

            if (recPad == -1) {

              _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch)));

            }

          }

        }

        // Then the rest, which depend on the kind of switch.

        switch (bc) {

          case Bytecodes::_tableswitch: {

            change_jump(bci, bci +1 + oldPad, false, break_bci, delta);

            // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct.

            int lo = int_at(bci + 1 + oldPad + 4 * 1);

            int hi = int_at(bci + 1 + oldPad + 4 * 2);

            int n = hi - lo + 1;

            for (int k = 0; k < n; k++) {

              change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta);

            }

            // Special next-bci calculation here...

            bci += 1 + oldPad + (n+3)*4;

            continue;

          }

          case Bytecodes::_lookupswitch:

          case Bytecodes::_fast_linearswitch:

          case Bytecodes::_fast_binaryswitch: {

            change_jump(bci, bci +1 + oldPad, false, break_bci, delta);

            // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct.

            int npairs = int_at(bci + 1 + oldPad + 4 * 1);

            for (int k = 0; k < npairs; k++) {

              change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta);

            }

            /* Special next-bci calculation here... */

            bci += 1 + oldPad + (2 + (npairs*2))*4;

            continue;

          }

          default:

            ShouldNotReachHere();

        }

      }

      default:

        break;

    }

    bci += rc_instr_len(bci);

  }

}

// The width of instruction at "pc" is changing by "delta".  Adjust the

// exception table, if any, of "rc->mb".

void Relocator::adjust_exception_table(int bci, int delta) {

  typeArrayOop table = method()->exception_table();

  for (int index = 0; index < table->length(); index +=4) {

    if (table->int_at(index) > bci) {

      table->int_at_put(index+0, table->int_at(index+0) + delta);

      table->int_at_put(index+1, table->int_at(index+1) + delta);

    } else if (bci < table->int_at(index+1)) {

      table->int_at_put(index+1, table->int_at(index+1) + delta);

    }

    if (table->int_at(index+2) > bci)

      table->int_at_put(index+2, table->int_at(index+2) + delta);

  }

}

// The width of instruction at "bci" is changing by "delta".  Adjust the line number table.

void Relocator::adjust_line_no_table(int bci, int delta) {

  if (method()->has_linenumber_table()) {

    CompressedLineNumberReadStream  reader(method()->compressed_linenumber_table());

    CompressedLineNumberWriteStream writer(64);  // plenty big for most line number tables

    while (reader.read_pair()) {

      int adjustment = (reader.bci() > bci) ? delta : 0;

      writer.write_pair(reader.bci() + adjustment, reader.line());

    }

    writer.write_terminator();

    set_compressed_line_number_table(writer.buffer());

    set_compressed_line_number_table_size(writer.position());

  }

}

// The width of instruction at "bci" is changing by "delta".  Adjust the local variable table.

void Relocator::adjust_local_var_table(int bci, int delta) {

  int localvariable_table_length = method()->localvariable_table_length();

  if (localvariable_table_length > 0) {

    LocalVariableTableElement* table = method()->localvariable_table_start();

    for (int i = 0; i < localvariable_table_length; i++) {

      u2 current_bci = table[i].start_bci;

      if (current_bci > bci) {

        table[i].start_bci = current_bci + delta;

      } else {

        u2 current_length = table[i].length;

        if (current_bci + current_length > bci) {

          table[i].length = current_length + delta;

        }

      }

    }

  }

}