/*

 * Copyright (c) 2000, 2019, 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 "precompiled.hpp"

#include "logging/log.hpp"

#include "memory/resourceArea.hpp"

#include "oops/constantPool.inline.hpp"

#include "oops/oop.inline.hpp"

#include "oops/symbol.hpp"

#include "prims/methodComparator.hpp"

#include "runtime/handles.inline.hpp"

#include "utilities/globalDefinitions.hpp"

BytecodeStream *MethodComparator::_s_old;

BytecodeStream *MethodComparator::_s_new;

ConstantPool* MethodComparator::_old_cp;

ConstantPool* MethodComparator::_new_cp;

bool MethodComparator::methods_EMCP(Method* old_method, Method* new_method) {

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

    return false;

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

    if (log_is_enabled(Debug, redefine, class, methodcomparator)) {

      ResourceMark rm;

      log_debug(redefine, class, methodcomparator)

        ("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();

  _s_old = &s_old;

  _s_new = &s_new;

  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::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 : {

    int cpci_old = _s_old->get_index_u2_cpcache();

    int cpci_new = _s_new->get_index_u2_cpcache();

    // 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::_invokedynamic: {

    int cpci_old = _s_old->get_index_u4();

    int cpci_new = _s_new->get_index_u4();

    // 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->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;

    // Translate object indexes to constant pool cache indexes.

    cpci_old = _old_cp->invokedynamic_cp_cache_index(cpci_old);

    cpci_new = _new_cp->invokedynamic_cp_cache_index(cpci_new);

    int cpi_old = _old_cp->cache()->entry_at(cpci_old)->constant_pool_index();

    int cpi_new = _new_cp->cache()->entry_at(cpci_new)->constant_pool_index();

    int bsm_old = _old_cp->bootstrap_method_ref_index_at(cpi_old);

    int bsm_new = _new_cp->bootstrap_method_ref_index_at(cpi_new);

    if (!pool_constants_same(bsm_old, bsm_new))

      return false;

    int cnt_old = _old_cp->bootstrap_argument_count_at(cpi_old);

    int cnt_new = _new_cp->bootstrap_argument_count_at(cpi_new);

    if (cnt_old != cnt_new)

      return false;

    for (int arg_i = 0; arg_i < cnt_old; arg_i++) {

      int idx_old = _old_cp->bootstrap_argument_index_at(cpi_old, arg_i);

      int idx_new = _new_cp->bootstrap_argument_index_at(cpi_new, arg_i);

      if (!pool_constants_same(idx_old, idx_new))

        return false;

    }

    break;

  }

  case Bytecodes::_ldc   : // fall through

  case Bytecodes::_ldc_w : {

    Bytecode_loadconstant ldc_old(_s_old->method(), _s_old->bci());

    Bytecode_loadconstant ldc_new(_s_new->method(), _s_new->bci());

    int cpi_old = ldc_old.pool_index();

    int cpi_new = ldc_new.pool_index();

    if (!pool_constants_same(cpi_old, cpi_new))

      return false;

    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 (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 (old_ofs != new_ofs)

      return false;

    break;

  }

  case Bytecodes::_lookupswitch : // fall through

  case Bytecodes::_tableswitch  : {

    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;

  }

  default:

    break;

  }

  return true;

}

bool MethodComparator::pool_constants_same(int cpi_old, int cpi_new) {

  constantTag tag_old = _old_cp->tag_at(cpi_old);

  constantTag tag_new = _new_cp->tag_at(cpi_new);

  if (tag_old.is_int() || tag_old.is_float()) {

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

      return false;

    if (tag_old.is_int()) {

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

        return false;

    } else {

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

      // This makes a difference for NaN constants.

      if (jint_cast(_old_cp->float_at(cpi_old)) != jint_cast(_new_cp->float_at(cpi_new)))

        return false;

    }

  } else if (tag_old.is_string() && tag_new.is_string()) {

    if (strcmp(_old_cp->string_at_noresolve(cpi_old),

               _new_cp->string_at_noresolve(cpi_new)) != 0)

      return false;

    if (_old_cp->is_pseudo_string_at(cpi_old) || _new_cp->is_pseudo_string_at(cpi_new))

      return (_old_cp->is_pseudo_string_at(cpi_old) == _new_cp->is_pseudo_string_at(cpi_new));

  } else if (tag_old.is_klass() || tag_old.is_unresolved_klass()) {

    // tag_old should be klass - 4881222

    if (! (tag_new.is_unresolved_klass() || tag_new.is_klass()))

      return false;

    if (_old_cp->klass_at_noresolve(cpi_old) !=

        _new_cp->klass_at_noresolve(cpi_new))

      return false;

  } else if (tag_old.is_method_type() && tag_new.is_method_type()) {

    int mti_old = _old_cp->method_type_index_at(cpi_old);

    int mti_new = _new_cp->method_type_index_at(cpi_new);

    if ((_old_cp->symbol_at(mti_old) != _new_cp->symbol_at(mti_new)))

      return false;

  } else if (tag_old.is_method_handle() && tag_new.is_method_handle()) {

    if (_old_cp->method_handle_ref_kind_at(cpi_old) !=

        _new_cp->method_handle_ref_kind_at(cpi_new))

      return false;

    int mhi_old = _old_cp->method_handle_index_at(cpi_old);

    int mhi_new = _new_cp->method_handle_index_at(cpi_new);

    if ((_old_cp->uncached_klass_ref_at_noresolve(mhi_old) != _new_cp->uncached_klass_ref_at_noresolve(mhi_new)) ||

        (_old_cp->uncached_name_ref_at(mhi_old) != _new_cp->uncached_name_ref_at(mhi_new)) ||

        (_old_cp->uncached_signature_ref_at(mhi_old) != _new_cp->uncached_signature_ref_at(mhi_new)))

      return false;

  } else {

    return false;  // unknown tag

  }

  return true;

}

int MethodComparator::check_stack_and_locals_size(Method* old_method, Method* 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;

}