aoqi@0: /*
aoqi@0:  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "oops/oop.inline.hpp"
aoqi@0: #include "oops/symbol.hpp"
aoqi@0: #include "prims/jvmtiRedefineClassesTrace.hpp"
aoqi@0: #include "prims/methodComparator.hpp"
aoqi@0: #include "runtime/handles.inline.hpp"
aoqi@0: #include "utilities/globalDefinitions.hpp"
aoqi@0: 
aoqi@0: BytecodeStream *MethodComparator::_s_old;
aoqi@0: BytecodeStream *MethodComparator::_s_new;
aoqi@0: ConstantPool* MethodComparator::_old_cp;
aoqi@0: ConstantPool* MethodComparator::_new_cp;
aoqi@0: BciMap *MethodComparator::_bci_map;
aoqi@0: bool MethodComparator::_switchable_test;
aoqi@0: GrowableArray<int> *MethodComparator::_fwd_jmps;
aoqi@0: 
aoqi@0: bool MethodComparator::methods_EMCP(Method* old_method, Method* new_method) {
aoqi@0:   if (old_method->code_size() != new_method->code_size())
aoqi@0:     return false;
aoqi@0:   if (check_stack_and_locals_size(old_method, new_method) != 0) {
aoqi@0:     // RC_TRACE macro has an embedded ResourceMark
aoqi@0:     RC_TRACE(0x00800000, ("Methods %s non-comparable with diagnosis %d",
aoqi@0:       old_method->name()->as_C_string(),
aoqi@0:       check_stack_and_locals_size(old_method, new_method)));
aoqi@0:     return false;
aoqi@0:   }
aoqi@0: 
aoqi@0:   _old_cp = old_method->constants();
aoqi@0:   _new_cp = new_method->constants();
aoqi@0:   BytecodeStream s_old(old_method);
aoqi@0:   BytecodeStream s_new(new_method);
aoqi@0:   _s_old = &s_old;
aoqi@0:   _s_new = &s_new;
aoqi@0:   _switchable_test = false;
aoqi@0:   Bytecodes::Code c_old, c_new;
aoqi@0: 
aoqi@0:   while ((c_old = s_old.next()) >= 0) {
aoqi@0:     if ((c_new = s_new.next()) < 0 || c_old != c_new)
aoqi@0:       return false;
aoqi@0: 
aoqi@0:     if (! args_same(c_old, c_new))
aoqi@0:       return false;
aoqi@0:   }
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: bool MethodComparator::methods_switchable(Method* old_method, Method* new_method,
aoqi@0:                                           BciMap &bci_map) {
aoqi@0:   if (old_method->code_size() > new_method->code_size())
aoqi@0:     // Something has definitely been deleted in the new method, compared to the old one.
aoqi@0:     return false;
aoqi@0: 
aoqi@0:   if (! check_stack_and_locals_size(old_method, new_method))
aoqi@0:     return false;
aoqi@0: 
aoqi@0:   _old_cp = old_method->constants();
aoqi@0:   _new_cp = new_method->constants();
aoqi@0:   BytecodeStream s_old(old_method);
aoqi@0:   BytecodeStream s_new(new_method);
aoqi@0:   _s_old = &s_old;
aoqi@0:   _s_new = &s_new;
aoqi@0:   _bci_map = &bci_map;
aoqi@0:   _switchable_test = true;
aoqi@0:   GrowableArray<int> fwd_jmps(16);
aoqi@0:   _fwd_jmps = &fwd_jmps;
aoqi@0:   Bytecodes::Code c_old, c_new;
aoqi@0: 
aoqi@0:   while ((c_old = s_old.next()) >= 0) {
aoqi@0:     if ((c_new = s_new.next()) < 0)
aoqi@0:       return false;
aoqi@0:     if (! (c_old == c_new && args_same(c_old, c_new))) {
aoqi@0:       int old_bci = s_old.bci();
aoqi@0:       int new_st_bci = s_new.bci();
aoqi@0:       bool found_match = false;
aoqi@0:       do {
aoqi@0:         c_new = s_new.next();
aoqi@0:         if (c_new == c_old && args_same(c_old, c_new)) {
aoqi@0:           found_match = true;
aoqi@0:           break;
aoqi@0:         }
aoqi@0:       } while (c_new >= 0);
aoqi@0:       if (! found_match)
aoqi@0:         return false;
aoqi@0:       int new_end_bci = s_new.bci();
aoqi@0:       bci_map.store_fragment_location(old_bci, new_st_bci, new_end_bci);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Now we can test all forward jumps
aoqi@0:   for (int i = 0; i < fwd_jmps.length() / 2; i++) {
aoqi@0:     if (! bci_map.old_and_new_locations_same(fwd_jmps.at(i*2), fwd_jmps.at(i*2+1))) {
aoqi@0:       RC_TRACE(0x00800000,
aoqi@0:         ("Fwd jump miss: old dest = %d, calc new dest = %d, act new dest = %d",
aoqi@0:         fwd_jmps.at(i*2), bci_map.new_bci_for_old(fwd_jmps.at(i*2)),
aoqi@0:         fwd_jmps.at(i*2+1)));
aoqi@0:       return false;
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: bool MethodComparator::args_same(Bytecodes::Code c_old, Bytecodes::Code c_new) {
aoqi@0:   // BytecodeStream returns the correct standard Java bytecodes for various "fast"
aoqi@0:   // bytecode versions, so we don't have to bother about them here..
aoqi@0:   switch (c_old) {
aoqi@0:   case Bytecodes::_new            : // fall through
aoqi@0:   case Bytecodes::_anewarray      : // fall through
aoqi@0:   case Bytecodes::_multianewarray : // fall through
aoqi@0:   case Bytecodes::_checkcast      : // fall through
aoqi@0:   case Bytecodes::_instanceof     : {
aoqi@0:     u2 cpi_old = _s_old->get_index_u2();
aoqi@0:     u2 cpi_new = _s_new->get_index_u2();
aoqi@0:     if ((_old_cp->klass_at_noresolve(cpi_old) != _new_cp->klass_at_noresolve(cpi_new)))
aoqi@0:         return false;
aoqi@0:     if (c_old == Bytecodes::_multianewarray &&
aoqi@0:         *(jbyte*)(_s_old->bcp() + 3) != *(jbyte*)(_s_new->bcp() + 3))
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_getstatic       : // fall through
aoqi@0:   case Bytecodes::_putstatic       : // fall through
aoqi@0:   case Bytecodes::_getfield        : // fall through
aoqi@0:   case Bytecodes::_putfield        : // fall through
aoqi@0:   case Bytecodes::_invokevirtual   : // fall through
aoqi@0:   case Bytecodes::_invokespecial   : // fall through
aoqi@0:   case Bytecodes::_invokestatic    : // fall through
aoqi@0:   case Bytecodes::_invokeinterface : {
aoqi@0:     int cpci_old = _s_old->get_index_u2_cpcache();
aoqi@0:     int cpci_new = _s_new->get_index_u2_cpcache();
aoqi@0:     // Check if the names of classes, field/method names and signatures at these indexes
aoqi@0:     // are the same. Indices which are really into constantpool cache (rather than constant
aoqi@0:     // pool itself) are accepted by the constantpool query routines below.
aoqi@0:     if ((_old_cp->klass_ref_at_noresolve(cpci_old) != _new_cp->klass_ref_at_noresolve(cpci_new)) ||
aoqi@0:         (_old_cp->name_ref_at(cpci_old) != _new_cp->name_ref_at(cpci_new)) ||
aoqi@0:         (_old_cp->signature_ref_at(cpci_old) != _new_cp->signature_ref_at(cpci_new)))
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0:   }
aoqi@0:   case Bytecodes::_invokedynamic: {
aoqi@0:     int cpci_old = _s_old->get_index_u4();
aoqi@0:     int cpci_new = _s_new->get_index_u4();
aoqi@0: 
aoqi@0:     // Check if the names of classes, field/method names and signatures at these indexes
aoqi@0:     // are the same. Indices which are really into constantpool cache (rather than constant
aoqi@0:     // pool itself) are accepted by the constantpool query routines below.
aoqi@0:     if ((_old_cp->name_ref_at(cpci_old) != _new_cp->name_ref_at(cpci_new)) ||
aoqi@0:         (_old_cp->signature_ref_at(cpci_old) != _new_cp->signature_ref_at(cpci_new)))
aoqi@0:       return false;
aoqi@0: 
aoqi@0:     // Translate object indexes to constant pool cache indexes.
aoqi@0:     cpci_old = _old_cp->invokedynamic_cp_cache_index(cpci_old);
aoqi@0:     cpci_new = _new_cp->invokedynamic_cp_cache_index(cpci_new);
aoqi@0: 
aoqi@0:     int cpi_old = _old_cp->cache()->entry_at(cpci_old)->constant_pool_index();
aoqi@0:     int cpi_new = _new_cp->cache()->entry_at(cpci_new)->constant_pool_index();
aoqi@0:     int bsm_old = _old_cp->invoke_dynamic_bootstrap_method_ref_index_at(cpi_old);
aoqi@0:     int bsm_new = _new_cp->invoke_dynamic_bootstrap_method_ref_index_at(cpi_new);
aoqi@0:     if (!pool_constants_same(bsm_old, bsm_new))
aoqi@0:       return false;
aoqi@0:     int cnt_old = _old_cp->invoke_dynamic_argument_count_at(cpi_old);
aoqi@0:     int cnt_new = _new_cp->invoke_dynamic_argument_count_at(cpi_new);
aoqi@0:     if (cnt_old != cnt_new)
aoqi@0:       return false;
aoqi@0:     for (int arg_i = 0; arg_i < cnt_old; arg_i++) {
aoqi@0:       int idx_old = _old_cp->invoke_dynamic_argument_index_at(cpi_old, arg_i);
aoqi@0:       int idx_new = _new_cp->invoke_dynamic_argument_index_at(cpi_new, arg_i);
aoqi@0:       if (!pool_constants_same(idx_old, idx_new))
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_ldc   : // fall through
aoqi@0:   case Bytecodes::_ldc_w : {
aoqi@0:     Bytecode_loadconstant ldc_old(_s_old->method(), _s_old->bci());
aoqi@0:     Bytecode_loadconstant ldc_new(_s_new->method(), _s_new->bci());
aoqi@0:     int cpi_old = ldc_old.pool_index();
aoqi@0:     int cpi_new = ldc_new.pool_index();
aoqi@0:     if (!pool_constants_same(cpi_old, cpi_new))
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_ldc2_w : {
aoqi@0:     u2 cpi_old = _s_old->get_index_u2();
aoqi@0:     u2 cpi_new = _s_new->get_index_u2();
aoqi@0:     constantTag tag_old = _old_cp->tag_at(cpi_old);
aoqi@0:     constantTag tag_new = _new_cp->tag_at(cpi_new);
aoqi@0:     if (tag_old.value() != tag_new.value())
aoqi@0:       return false;
aoqi@0:     if (tag_old.is_long()) {
aoqi@0:       if (_old_cp->long_at(cpi_old) != _new_cp->long_at(cpi_new))
aoqi@0:         return false;
aoqi@0:     } else {
aoqi@0:       // Use jlong_cast to compare the bits rather than numerical values.
aoqi@0:       // This makes a difference for NaN constants.
aoqi@0:       if (jlong_cast(_old_cp->double_at(cpi_old)) != jlong_cast(_new_cp->double_at(cpi_new)))
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_bipush :
aoqi@0:     if (_s_old->bcp()[1] != _s_new->bcp()[1])
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0: 
aoqi@0:   case Bytecodes::_sipush    :
aoqi@0:     if (_s_old->get_index_u2() != _s_new->get_index_u2())
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0: 
aoqi@0:   case Bytecodes::_aload  : // fall through
aoqi@0:   case Bytecodes::_astore : // fall through
aoqi@0:   case Bytecodes::_dload  : // fall through
aoqi@0:   case Bytecodes::_dstore : // fall through
aoqi@0:   case Bytecodes::_fload  : // fall through
aoqi@0:   case Bytecodes::_fstore : // fall through
aoqi@0:   case Bytecodes::_iload  : // fall through
aoqi@0:   case Bytecodes::_istore : // fall through
aoqi@0:   case Bytecodes::_lload  : // fall through
aoqi@0:   case Bytecodes::_lstore : // fall through
aoqi@0:   case Bytecodes::_ret    :
aoqi@0:     if (_s_old->is_wide() != _s_new->is_wide())
aoqi@0:       return false;
aoqi@0:     if (_s_old->get_index() != _s_new->get_index())
aoqi@0:       return false;
aoqi@0:     break;
aoqi@0: 
aoqi@0:   case Bytecodes::_goto      : // fall through
aoqi@0:   case Bytecodes::_if_acmpeq : // fall through
aoqi@0:   case Bytecodes::_if_acmpne : // fall through
aoqi@0:   case Bytecodes::_if_icmpeq : // fall through
aoqi@0:   case Bytecodes::_if_icmpne : // fall through
aoqi@0:   case Bytecodes::_if_icmplt : // fall through
aoqi@0:   case Bytecodes::_if_icmpge : // fall through
aoqi@0:   case Bytecodes::_if_icmpgt : // fall through
aoqi@0:   case Bytecodes::_if_icmple : // fall through
aoqi@0:   case Bytecodes::_ifeq      : // fall through
aoqi@0:   case Bytecodes::_ifne      : // fall through
aoqi@0:   case Bytecodes::_iflt      : // fall through
aoqi@0:   case Bytecodes::_ifge      : // fall through
aoqi@0:   case Bytecodes::_ifgt      : // fall through
aoqi@0:   case Bytecodes::_ifle      : // fall through
aoqi@0:   case Bytecodes::_ifnonnull : // fall through
aoqi@0:   case Bytecodes::_ifnull    : // fall through
aoqi@0:   case Bytecodes::_jsr       : {
aoqi@0:     int old_ofs = _s_old->bytecode().get_offset_s2(c_old);
aoqi@0:     int new_ofs = _s_new->bytecode().get_offset_s2(c_new);
aoqi@0:     if (_switchable_test) {
aoqi@0:       int old_dest = _s_old->bci() + old_ofs;
aoqi@0:       int new_dest = _s_new->bci() + new_ofs;
aoqi@0:       if (old_ofs < 0 && new_ofs < 0) {
aoqi@0:         if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))
aoqi@0:           return false;
aoqi@0:       } else if (old_ofs > 0 && new_ofs > 0) {
aoqi@0:         _fwd_jmps->append(old_dest);
aoqi@0:         _fwd_jmps->append(new_dest);
aoqi@0:       } else {
aoqi@0:         return false;
aoqi@0:       }
aoqi@0:     } else {
aoqi@0:       if (old_ofs != new_ofs)
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_iinc :
aoqi@0:     if (_s_old->is_wide() != _s_new->is_wide())
aoqi@0:       return false;
aoqi@0:     if (! _s_old->is_wide()) {
aoqi@0:       // We could use get_index_u1 and get_constant_u1, but it's simpler to grab both bytes at once:
aoqi@0:       if (Bytes::get_Java_u2(_s_old->bcp() + 1) != Bytes::get_Java_u2(_s_new->bcp() + 1))
aoqi@0:         return false;
aoqi@0:     } else {
aoqi@0:       // We could use get_index_u2 and get_constant_u2, but it's simpler to grab all four bytes at once:
aoqi@0:       if (Bytes::get_Java_u4(_s_old->bcp() + 1) != Bytes::get_Java_u4(_s_new->bcp() + 1))
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0: 
aoqi@0:   case Bytecodes::_goto_w : // fall through
aoqi@0:   case Bytecodes::_jsr_w  : {
aoqi@0:     int old_ofs = _s_old->bytecode().get_offset_s4(c_old);
aoqi@0:     int new_ofs = _s_new->bytecode().get_offset_s4(c_new);
aoqi@0:     if (_switchable_test) {
aoqi@0:       int old_dest = _s_old->bci() + old_ofs;
aoqi@0:       int new_dest = _s_new->bci() + new_ofs;
aoqi@0:       if (old_ofs < 0 && new_ofs < 0) {
aoqi@0:         if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))
aoqi@0:           return false;
aoqi@0:       } else if (old_ofs > 0 && new_ofs > 0) {
aoqi@0:         _fwd_jmps->append(old_dest);
aoqi@0:         _fwd_jmps->append(new_dest);
aoqi@0:       } else {
aoqi@0:         return false;
aoqi@0:       }
aoqi@0:     } else {
aoqi@0:       if (old_ofs != new_ofs)
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0:   }
aoqi@0: 
aoqi@0:   case Bytecodes::_lookupswitch : // fall through
aoqi@0:   case Bytecodes::_tableswitch  : {
aoqi@0:     if (_switchable_test) {
aoqi@0:       address aligned_bcp_old = (address) round_to((intptr_t)_s_old->bcp() + 1, jintSize);
aoqi@0:       address aligned_bcp_new = (address) round_to((intptr_t)_s_new->bcp() + 1, jintSize);
aoqi@0:       int default_old = (int) Bytes::get_Java_u4(aligned_bcp_old);
aoqi@0:       int default_new = (int) Bytes::get_Java_u4(aligned_bcp_new);
aoqi@0:       _fwd_jmps->append(_s_old->bci() + default_old);
aoqi@0:       _fwd_jmps->append(_s_new->bci() + default_new);
aoqi@0:       if (c_old == Bytecodes::_lookupswitch) {
aoqi@0:         int npairs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);
aoqi@0:         int npairs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);
aoqi@0:         if (npairs_old != npairs_new)
aoqi@0:           return false;
aoqi@0:         for (int i = 0; i < npairs_old; i++) {
aoqi@0:           int match_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i)*jintSize);
aoqi@0:           int match_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i)*jintSize);
aoqi@0:           if (match_old != match_new)
aoqi@0:             return false;
aoqi@0:           int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i+1)*jintSize);
aoqi@0:           int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i+1)*jintSize);
aoqi@0:           _fwd_jmps->append(_s_old->bci() + ofs_old);
aoqi@0:           _fwd_jmps->append(_s_new->bci() + ofs_new);
aoqi@0:         }
aoqi@0:       } else if (c_old == Bytecodes::_tableswitch) {
aoqi@0:         int lo_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);
aoqi@0:         int lo_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);
aoqi@0:         if (lo_old != lo_new)
aoqi@0:           return false;
aoqi@0:         int hi_old = (int) Bytes::get_Java_u4(aligned_bcp_old + 2*jintSize);
aoqi@0:         int hi_new = (int) Bytes::get_Java_u4(aligned_bcp_new + 2*jintSize);
aoqi@0:         if (hi_old != hi_new)
aoqi@0:           return false;
aoqi@0:         for (int i = 0; i < hi_old - lo_old + 1; i++) {
aoqi@0:           int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (3+i)*jintSize);
aoqi@0:           int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (3+i)*jintSize);
aoqi@0:           _fwd_jmps->append(_s_old->bci() + ofs_old);
aoqi@0:           _fwd_jmps->append(_s_new->bci() + ofs_new);
aoqi@0:         }
aoqi@0:       }
aoqi@0:     } else { // !_switchable_test, can use fast rough compare
aoqi@0:       int len_old = _s_old->instruction_size();
aoqi@0:       int len_new = _s_new->instruction_size();
aoqi@0:       if (len_old != len_new)
aoqi@0:         return false;
aoqi@0:       if (memcmp(_s_old->bcp(), _s_new->bcp(), len_old) != 0)
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:     break;
aoqi@0:   }
aoqi@0:   }
aoqi@0: 
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: bool MethodComparator::pool_constants_same(int cpi_old, int cpi_new) {
aoqi@0:   constantTag tag_old = _old_cp->tag_at(cpi_old);
aoqi@0:   constantTag tag_new = _new_cp->tag_at(cpi_new);
aoqi@0:   if (tag_old.is_int() || tag_old.is_float()) {
aoqi@0:     if (tag_old.value() != tag_new.value())
aoqi@0:       return false;
aoqi@0:     if (tag_old.is_int()) {
aoqi@0:       if (_old_cp->int_at(cpi_old) != _new_cp->int_at(cpi_new))
aoqi@0:         return false;
aoqi@0:     } else {
aoqi@0:       // Use jint_cast to compare the bits rather than numerical values.
aoqi@0:       // This makes a difference for NaN constants.
aoqi@0:       if (jint_cast(_old_cp->float_at(cpi_old)) != jint_cast(_new_cp->float_at(cpi_new)))
aoqi@0:         return false;
aoqi@0:     }
aoqi@0:   } else if (tag_old.is_string() && tag_new.is_string()) {
aoqi@0:     if (strcmp(_old_cp->string_at_noresolve(cpi_old),
aoqi@0:                _new_cp->string_at_noresolve(cpi_new)) != 0)
aoqi@0:       return false;
aoqi@0:   } else if (tag_old.is_klass() || tag_old.is_unresolved_klass()) {
aoqi@0:     // tag_old should be klass - 4881222
aoqi@0:     if (! (tag_new.is_unresolved_klass() || tag_new.is_klass()))
aoqi@0:       return false;
aoqi@0:     if (_old_cp->klass_at_noresolve(cpi_old) !=
aoqi@0:         _new_cp->klass_at_noresolve(cpi_new))
aoqi@0:       return false;
aoqi@0:   } else if (tag_old.is_method_type() && tag_new.is_method_type()) {
aoqi@0:     int mti_old = _old_cp->method_type_index_at(cpi_old);
aoqi@0:     int mti_new = _new_cp->method_type_index_at(cpi_new);
aoqi@0:     if ((_old_cp->symbol_at(mti_old) != _new_cp->symbol_at(mti_new)))
aoqi@0:       return false;
aoqi@0:   } else if (tag_old.is_method_handle() && tag_new.is_method_handle()) {
aoqi@0:     if (_old_cp->method_handle_ref_kind_at(cpi_old) !=
aoqi@0:         _new_cp->method_handle_ref_kind_at(cpi_new))
aoqi@0:       return false;
aoqi@0:     int mhi_old = _old_cp->method_handle_index_at(cpi_old);
aoqi@0:     int mhi_new = _new_cp->method_handle_index_at(cpi_new);
aoqi@0:     if ((_old_cp->uncached_klass_ref_at_noresolve(mhi_old) != _new_cp->uncached_klass_ref_at_noresolve(mhi_new)) ||
aoqi@0:         (_old_cp->uncached_name_ref_at(mhi_old) != _new_cp->uncached_name_ref_at(mhi_new)) ||
aoqi@0:         (_old_cp->uncached_signature_ref_at(mhi_old) != _new_cp->uncached_signature_ref_at(mhi_new)))
aoqi@0:       return false;
aoqi@0:   } else {
aoqi@0:     return false;  // unknown tag
aoqi@0:   }
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: int MethodComparator::check_stack_and_locals_size(Method* old_method, Method* new_method) {
aoqi@0:   if (old_method->max_stack() != new_method->max_stack()) {
aoqi@0:     return 1;
aoqi@0:   } else if (old_method->max_locals() != new_method->max_locals()) {
aoqi@0:     return 2;
aoqi@0:   } else if (old_method->size_of_parameters() != new_method->size_of_parameters()) {
aoqi@0:     return 3;
aoqi@0:   } else return 0;
aoqi@0: }