/*

 * Copyright (c) 2000, 2010, 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/_methodComparator.cpp.incl"

BytecodeStream *MethodComparator::_s_old;

BytecodeStream *MethodComparator::_s_new;

constantPoolOop MethodComparator::_old_cp;

constantPoolOop MethodComparator::_new_cp;

BciMap *MethodComparator::_bci_map;

bool MethodComparator::_switchable_test;

GrowableArray<int> *MethodComparator::_fwd_jmps;

bool MethodComparator::methods_EMCP(methodOop old_method, methodOop new_method) {

  if (old_method->code_size() != new_method->code_size())

    return false;

  if (check_stack_and_locals_size(old_method, new_method) != 0) {

    // RC_TRACE macro has an embedded ResourceMark

    RC_TRACE(0x00800000, ("Methods %s non-comparable with diagnosis %d",

      old_method->name()->as_C_string(),

      check_stack_and_locals_size(old_method, new_method)));

    return false;

  }

  _old_cp = old_method->constants();

  _new_cp = new_method->constants();

  BytecodeStream s_old(old_method);

  BytecodeStream s_new(new_method);

  _s_old = &s_old;

  _s_new = &s_new;

  _switchable_test = false;

  Bytecodes::Code c_old, c_new;

  while ((c_old = s_old.next()) >= 0) {

    if ((c_new = s_new.next()) < 0 || c_old != c_new)

      return false;

    if (! args_same(c_old, c_new))

      return false;

  }

  return true;

}

bool MethodComparator::methods_switchable(methodOop old_method, methodOop new_method,

                                          BciMap &bci_map) {

  if (old_method->code_size() > new_method->code_size())

    // Something has definitely been deleted in the new method, compared to the old one.

    return false;

  if (! check_stack_and_locals_size(old_method, new_method))

    return false;

  _old_cp = old_method->constants();

  _new_cp = new_method->constants();

  BytecodeStream s_old(old_method);

  BytecodeStream s_new(new_method);

  _s_old = &s_old;

  _s_new = &s_new;

  _bci_map = &bci_map;

  _switchable_test = true;

  GrowableArray<int> fwd_jmps(16);

  _fwd_jmps = &fwd_jmps;

  Bytecodes::Code c_old, c_new;

  while ((c_old = s_old.next()) >= 0) {

    if ((c_new = s_new.next()) < 0)

      return false;

    if (! (c_old == c_new && args_same(c_old, c_new))) {

      int old_bci = s_old.bci();

      int new_st_bci = s_new.bci();

      bool found_match = false;

      do {

        c_new = s_new.next();

        if (c_new == c_old && args_same(c_old, c_new)) {

          found_match = true;

          break;

        }

      } while (c_new >= 0);

      if (! found_match)

        return false;

      int new_end_bci = s_new.bci();

      bci_map.store_fragment_location(old_bci, new_st_bci, new_end_bci);

    }

  }

  // Now we can test all forward jumps

  for (int i = 0; i < fwd_jmps.length() / 2; i++) {

    if (! bci_map.old_and_new_locations_same(fwd_jmps.at(i*2), fwd_jmps.at(i*2+1))) {

      RC_TRACE(0x00800000,

        ("Fwd jump miss: old dest = %d, calc new dest = %d, act new dest = %d",

        fwd_jmps.at(i*2), bci_map.new_bci_for_old(fwd_jmps.at(i*2)),

        fwd_jmps.at(i*2+1)));

      return false;

    }

  }

  return true;

}

bool MethodComparator::args_same(Bytecodes::Code c_old, Bytecodes::Code c_new) {

  // BytecodeStream returns the correct standard Java bytecodes for various "fast"

  // bytecode versions, so we don't have to bother about them here..

  switch (c_old) {

  case Bytecodes::_new            : // fall through

  case Bytecodes::_anewarray      : // fall through

  case Bytecodes::_multianewarray : // fall through

  case Bytecodes::_checkcast      : // fall through

  case Bytecodes::_instanceof     : {

    u2 cpi_old = _s_old->get_index_u2();

    u2 cpi_new = _s_new->get_index_u2();

    if ((_old_cp->klass_at_noresolve(cpi_old) != _new_cp->klass_at_noresolve(cpi_new)))

        return false;

    if (c_old == Bytecodes::_multianewarray &&

        *(jbyte*)(_s_old->bcp() + 3) != *(jbyte*)(_s_new->bcp() + 3))

      return false;

    break;

  }

  case Bytecodes::_getstatic       : // fall through

  case Bytecodes::_putstatic       : // fall through

  case Bytecodes::_getfield        : // fall through

  case Bytecodes::_putfield        : // fall through

  case Bytecodes::_invokevirtual   : // fall through

  case Bytecodes::_invokespecial   : // fall through

  case Bytecodes::_invokestatic    : // fall through

  case Bytecodes::_invokeinterface : {

    // Check if the names of classes, field/method names and signatures at these indexes

    // are the same. Indices which are really into constantpool cache (rather than constant

    // pool itself) are accepted by the constantpool query routines below.

    if ((_old_cp->klass_ref_at_noresolve(cpci_old) != _new_cp->klass_ref_at_noresolve(cpci_new)) ||

        (_old_cp->name_ref_at(cpci_old) != _new_cp->name_ref_at(cpci_new)) ||

        (_old_cp->signature_ref_at(cpci_old) != _new_cp->signature_ref_at(cpci_new)))

      return false;

    break;

  }

  case Bytecodes::_ldc   : // fall through

  case Bytecodes::_ldc_w : {

    Bytecode_loadconstant* ldc_old = Bytecode_loadconstant_at(_s_old->method(), _s_old->bci());

    Bytecode_loadconstant* ldc_new = Bytecode_loadconstant_at(_s_new->method(), _s_new->bci());

    int cpi_old = ldc_old->pool_index();

    int cpi_new = ldc_new->pool_index();

    break;

  }

  case Bytecodes::_ldc2_w : {

    u2 cpi_old = _s_old->get_index_u2();

    u2 cpi_new = _s_new->get_index_u2();

    constantTag tag_old = _old_cp->tag_at(cpi_old);

    constantTag tag_new = _new_cp->tag_at(cpi_new);

    if (tag_old.value() != tag_new.value())

      return false;

    if (tag_old.is_long()) {

      if (_old_cp->long_at(cpi_old) != _new_cp->long_at(cpi_new))

        return false;

    } else {

      // Use jlong_cast to compare the bits rather than numerical values.

      // This makes a difference for NaN constants.

      if (jlong_cast(_old_cp->double_at(cpi_old)) != jlong_cast(_new_cp->double_at(cpi_new)))

        return false;

    }

    break;

  }

  case Bytecodes::_bipush :

    if (_s_old->bcp()[1] != _s_new->bcp()[1])

      return false;

    break;

  case Bytecodes::_sipush    :

    if (_s_old->get_index_u2() != _s_new->get_index_u2())

      return false;

    break;

  case Bytecodes::_aload  : // fall through

  case Bytecodes::_astore : // fall through

  case Bytecodes::_dload  : // fall through

  case Bytecodes::_dstore : // fall through

  case Bytecodes::_fload  : // fall through

  case Bytecodes::_fstore : // fall through

  case Bytecodes::_iload  : // fall through

  case Bytecodes::_istore : // fall through

  case Bytecodes::_lload  : // fall through

  case Bytecodes::_lstore : // fall through

  case Bytecodes::_ret    :

    if (_s_old->is_wide() != _s_new->is_wide())

      return false;

    if (_s_old->get_index() != _s_new->get_index())

      return false;

    break;

  case Bytecodes::_goto      : // fall through

  case Bytecodes::_if_acmpeq : // fall through

  case Bytecodes::_if_acmpne : // fall through

  case Bytecodes::_if_icmpeq : // fall through

  case Bytecodes::_if_icmpne : // fall through

  case Bytecodes::_if_icmplt : // fall through

  case Bytecodes::_if_icmpge : // fall through

  case Bytecodes::_if_icmpgt : // fall through

  case Bytecodes::_if_icmple : // fall through

  case Bytecodes::_ifeq      : // fall through

  case Bytecodes::_ifne      : // fall through

  case Bytecodes::_iflt      : // fall through

  case Bytecodes::_ifge      : // fall through

  case Bytecodes::_ifgt      : // fall through

  case Bytecodes::_ifle      : // fall through

  case Bytecodes::_ifnonnull : // fall through

  case Bytecodes::_ifnull    : // fall through

  case Bytecodes::_jsr       : {

    int old_ofs = _s_old->bytecode()->get_offset_s2(c_old);

    int new_ofs = _s_new->bytecode()->get_offset_s2(c_new);

    if (_switchable_test) {

      int old_dest = _s_old->bci() + old_ofs;

      int new_dest = _s_new->bci() + new_ofs;

      if (old_ofs < 0 && new_ofs < 0) {

        if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))

          return false;

      } else if (old_ofs > 0 && new_ofs > 0) {

        _fwd_jmps->append(old_dest);

        _fwd_jmps->append(new_dest);

      } else {

        return false;

      }

    } else {

      if (old_ofs != new_ofs)

        return false;

    }

    break;

  }

  case Bytecodes::_iinc :

    if (_s_old->is_wide() != _s_new->is_wide())

      return false;

    if (! _s_old->is_wide()) {

      // We could use get_index_u1 and get_constant_u1, but it's simpler to grab both bytes at once:

      if (Bytes::get_Java_u2(_s_old->bcp() + 1) != Bytes::get_Java_u2(_s_new->bcp() + 1))

        return false;

    } else {

      // We could use get_index_u2 and get_constant_u2, but it's simpler to grab all four bytes at once:

      if (Bytes::get_Java_u4(_s_old->bcp() + 1) != Bytes::get_Java_u4(_s_new->bcp() + 1))

        return false;

    }

    break;

  case Bytecodes::_goto_w : // fall through

  case Bytecodes::_jsr_w  : {

    int old_ofs = _s_old->bytecode()->get_offset_s4(c_old);

    int new_ofs = _s_new->bytecode()->get_offset_s4(c_new);

    if (_switchable_test) {

      int old_dest = _s_old->bci() + old_ofs;

      int new_dest = _s_new->bci() + new_ofs;

      if (old_ofs < 0 && new_ofs < 0) {

        if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))

          return false;

      } else if (old_ofs > 0 && new_ofs > 0) {

        _fwd_jmps->append(old_dest);

        _fwd_jmps->append(new_dest);

      } else {

        return false;

      }

    } else {

      if (old_ofs != new_ofs)

        return false;

    }

    break;

  }

  case Bytecodes::_lookupswitch : // fall through

  case Bytecodes::_tableswitch  : {

    if (_switchable_test) {

      address aligned_bcp_old = (address) round_to((intptr_t)_s_old->bcp() + 1, jintSize);

      address aligned_bcp_new = (address) round_to((intptr_t)_s_new->bcp() + 1, jintSize);

      int default_old = (int) Bytes::get_Java_u4(aligned_bcp_old);

      int default_new = (int) Bytes::get_Java_u4(aligned_bcp_new);

      _fwd_jmps->append(_s_old->bci() + default_old);

      _fwd_jmps->append(_s_new->bci() + default_new);

      if (c_old == Bytecodes::_lookupswitch) {

        int npairs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);

        int npairs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);

        if (npairs_old != npairs_new)

          return false;

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

          int match_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i)*jintSize);

          int match_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i)*jintSize);

          if (match_old != match_new)

            return false;

          int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i+1)*jintSize);

          int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i+1)*jintSize);

          _fwd_jmps->append(_s_old->bci() + ofs_old);

          _fwd_jmps->append(_s_new->bci() + ofs_new);

        }

      } else if (c_old == Bytecodes::_tableswitch) {

        int lo_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);

        int lo_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);

        if (lo_old != lo_new)

          return false;

        int hi_old = (int) Bytes::get_Java_u4(aligned_bcp_old + 2*jintSize);

        int hi_new = (int) Bytes::get_Java_u4(aligned_bcp_new + 2*jintSize);

        if (hi_old != hi_new)

          return false;

        for (int i = 0; i < hi_old - lo_old + 1; i++) {

          int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (3+i)*jintSize);

          int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (3+i)*jintSize);

          _fwd_jmps->append(_s_old->bci() + ofs_old);

          _fwd_jmps->append(_s_new->bci() + ofs_new);

        }

      }

    } else { // !_switchable_test, can use fast rough compare

      int len_old = _s_old->instruction_size();

      int len_new = _s_new->instruction_size();

      if (len_old != len_new)

        return false;

      if (memcmp(_s_old->bcp(), _s_new->bcp(), len_old) != 0)

        return false;

    }

    break;

  }

  }

  return true;

}

int MethodComparator::check_stack_and_locals_size(methodOop old_method, methodOop new_method) {

  if (old_method->max_stack() != new_method->max_stack()) {

    return 1;

  } else if (old_method->max_locals() != new_method->max_locals()) {

    return 2;

  } else if (old_method->size_of_parameters() != new_method->size_of_parameters()) {

    return 3;

  } else return 0;

}