Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2003-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 # include "incls/_precompiled.incl"

 # include "incls/_jvmtiRedefineClasses.cpp.incl"

 objArrayOop VM_RedefineClasses::_old_methods = NULL;

 objArrayOop VM_RedefineClasses::_new_methods = NULL;

 methodOop*  VM_RedefineClasses::_matching_old_methods = NULL;

 methodOop*  VM_RedefineClasses::_matching_new_methods = NULL;

 methodOop*  VM_RedefineClasses::_deleted_methods      = NULL;

 methodOop*  VM_RedefineClasses::_added_methods        = NULL;

 int         VM_RedefineClasses::_matching_methods_length = 0;

 int         VM_RedefineClasses::_deleted_methods_length  = 0;

 int         VM_RedefineClasses::_added_methods_length    = 0;

 klassOop    VM_RedefineClasses::_the_class_oop = NULL;

 VM_RedefineClasses::VM_RedefineClasses(jint class_count,

                                        const jvmtiClassDefinition *class_defs,

                                        JvmtiClassLoadKind class_load_kind) {

   _class_count = class_count;

   _class_defs = class_defs;

   _class_load_kind = class_load_kind;

   _res = JVMTI_ERROR_NONE;

 }

 bool VM_RedefineClasses::doit_prologue() {

   if (_class_count == 0) {

     _res = JVMTI_ERROR_NONE;

     return false;

   }

   if (_class_defs == NULL) {

     _res = JVMTI_ERROR_NULL_POINTER;

     return false;

   }

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

     if (_class_defs[i].klass == NULL) {

       _res = JVMTI_ERROR_INVALID_CLASS;

       return false;

     }

     if (_class_defs[i].class_byte_count == 0) {

       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;

       return false;

     }

     if (_class_defs[i].class_bytes == NULL) {

       _res = JVMTI_ERROR_NULL_POINTER;

       return false;

     }

   }

   // Start timer after all the sanity checks; not quite accurate, but

   // better than adding a bunch of stop() calls.

   RC_TIMER_START(_timer_vm_op_prologue);

   // We first load new class versions in the prologue, because somewhere down the

   // call chain it is required that the current thread is a Java thread.

   _res = load_new_class_versions(Thread::current());

   if (_res != JVMTI_ERROR_NONE) {

     // Free os::malloc allocated memory in load_new_class_version.

     os::free(_scratch_classes);

     RC_TIMER_STOP(_timer_vm_op_prologue);

     return false;

   }

   RC_TIMER_STOP(_timer_vm_op_prologue);

   return true;

 }

 void VM_RedefineClasses::doit() {

   Thread *thread = Thread::current();

   if (UseSharedSpaces) {

     // Sharing is enabled so we remap the shared readonly space to

     // shared readwrite, private just in case we need to redefine

     // a shared class. We do the remap during the doit() phase of

     // the safepoint to be safer.

     if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {

       RC_TRACE_WITH_THREAD(0x00000001, thread,

         ("failed to remap shared readonly space to readwrite, private"));

       _res = JVMTI_ERROR_INTERNAL;

       return;

     }

   }

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

     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);

   }

   // Disable any dependent concurrent compilations

   SystemDictionary::notice_modification();

   // Set flag indicating that some invariants are no longer true.

   // See jvmtiExport.hpp for detailed explanation.

   JvmtiExport::set_has_redefined_a_class();

 #ifdef ASSERT

   SystemDictionary::classes_do(check_class, thread);

 #endif

 }

 void VM_RedefineClasses::doit_epilogue() {

   // Free os::malloc allocated memory.

   // The memory allocated in redefine will be free'ed in next VM operation.

   os::free(_scratch_classes);

   if (RC_TRACE_ENABLED(0x00000004)) {

     // Used to have separate timers for "doit" and "all", but the timer

     // overhead skewed the measurements.

     jlong doit_time = _timer_rsc_phase1.milliseconds() +

                       _timer_rsc_phase2.milliseconds();

     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;

     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT

       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,

       _timer_vm_op_prologue.milliseconds(), doit_time));

     RC_TRACE(0x00000004,

       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,

        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));

   }

 }

 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {

   // classes for primitives cannot be redefined

   if (java_lang_Class::is_primitive(klass_mirror)) {

     return false;

   }

   klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);

   // classes for arrays cannot be redefined

   if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {

     return false;

   }

   return true;

 }

 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p

 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For

 // direct CP entries, there is just the current entry to append. For

 // indirect and double-indirect CP entries, there are zero or more

 // referenced CP entries along with the current entry to append.

 // Indirect and double-indirect CP entries are handled by recursive

 // calls to append_entry() as needed. The referenced CP entries are

 // always appended to *merge_cp_p before the referee CP entry. These

 // referenced CP entries may already exist in *merge_cp_p in which case

 // there is nothing extra to append and only the current entry is

 // appended.

 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,

        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,

        TRAPS) {

   // append is different depending on entry tag type

   switch (scratch_cp->tag_at(scratch_i).value()) {

     // The old verifier is implemented outside the VM. It loads classes,

     // but does not resolve constant pool entries directly so we never

     // see Class entries here with the old verifier. Similarly the old

     // verifier does not like Class entries in the input constant pool.

     // The split-verifier is implemented in the VM so it can optionally

     // and directly resolve constant pool entries to load classes. The

     // split-verifier can accept either Class entries or UnresolvedClass

     // entries in the input constant pool. We revert the appended copy

     // back to UnresolvedClass so that either verifier will be happy

     // with the constant pool entry.

     case JVM_CONSTANT_Class:

     {

       // revert the copy to JVM_CONSTANT_UnresolvedClass

       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,

         scratch_cp->klass_name_at(scratch_i));

       if (scratch_i != *merge_cp_length_p) {

         // The new entry in *merge_cp_p is at a different index than

         // the new entry in scratch_cp so we need to map the index values.

         map_index(scratch_cp, scratch_i, *merge_cp_length_p);

       }

       (*merge_cp_length_p)++;

     } break;

     // these are direct CP entries so they can be directly appended,

     // but double and long take two constant pool entries

     case JVM_CONSTANT_Double:  // fall through

     case JVM_CONSTANT_Long:

     {

       scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p,

         THREAD);

       if (scratch_i != *merge_cp_length_p) {

         // The new entry in *merge_cp_p is at a different index than

         // the new entry in scratch_cp so we need to map the index values.

         map_index(scratch_cp, scratch_i, *merge_cp_length_p);

       }

       (*merge_cp_length_p) += 2;

     } break;

     // these are direct CP entries so they can be directly appended

     case JVM_CONSTANT_Float:   // fall through

     case JVM_CONSTANT_Integer: // fall through

     case JVM_CONSTANT_Utf8:    // fall through

     // This was an indirect CP entry, but it has been changed into

     // an interned string so this entry can be directly appended.

     case JVM_CONSTANT_String:      // fall through

     // These were indirect CP entries, but they have been changed into

     // symbolOops so these entries can be directly appended.

     case JVM_CONSTANT_UnresolvedClass:  // fall through

     case JVM_CONSTANT_UnresolvedString:

     {

       scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p,

         THREAD);

       if (scratch_i != *merge_cp_length_p) {

         // The new entry in *merge_cp_p is at a different index than

         // the new entry in scratch_cp so we need to map the index values.

         map_index(scratch_cp, scratch_i, *merge_cp_length_p);

       }

       (*merge_cp_length_p)++;

     } break;

     // this is an indirect CP entry so it needs special handling

     case JVM_CONSTANT_NameAndType:

     {

       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);

       int new_name_ref_i = 0;

       bool match = (name_ref_i < *merge_cp_length_p) &&

         scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,

           THREAD);

       if (!match) {

         // forward reference in *merge_cp_p or not a direct match

         int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,

           THREAD);

         if (found_i != 0) {

           guarantee(found_i != name_ref_i,

             "compare_entry_to() and find_matching_entry() do not agree");

           // Found a matching entry somewhere else in *merge_cp_p so

           // just need a mapping entry.

           new_name_ref_i = found_i;

           map_index(scratch_cp, name_ref_i, found_i);

         } else {

           // no match found so we have to append this entry to *merge_cp_p

           append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,

             THREAD);

           // The above call to append_entry() can only append one entry

           // so the post call query of *merge_cp_length_p is only for

           // the sake of consistency.

           new_name_ref_i = *merge_cp_length_p - 1;

         }

       }

       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);

       int new_signature_ref_i = 0;

       match = (signature_ref_i < *merge_cp_length_p) &&

         scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,

           signature_ref_i, THREAD);

       if (!match) {

         // forward reference in *merge_cp_p or not a direct match

         int found_i = scratch_cp->find_matching_entry(signature_ref_i,

           *merge_cp_p, THREAD);

         if (found_i != 0) {

           guarantee(found_i != signature_ref_i,

             "compare_entry_to() and find_matching_entry() do not agree");

           // Found a matching entry somewhere else in *merge_cp_p so

           // just need a mapping entry.

           new_signature_ref_i = found_i;

           map_index(scratch_cp, signature_ref_i, found_i);

         } else {

           // no match found so we have to append this entry to *merge_cp_p

           append_entry(scratch_cp, signature_ref_i, merge_cp_p,

             merge_cp_length_p, THREAD);

           // The above call to append_entry() can only append one entry

           // so the post call query of *merge_cp_length_p is only for

           // the sake of consistency.

           new_signature_ref_i = *merge_cp_length_p - 1;

         }

       }

       // If the referenced entries already exist in *merge_cp_p, then

       // both new_name_ref_i and new_signature_ref_i will both be 0.

       // In that case, all we are appending is the current entry.

       if (new_name_ref_i == 0) {

         new_name_ref_i = name_ref_i;

       } else {

         RC_TRACE(0x00080000,

           ("NameAndType entry@%d name_ref_index change: %d to %d",

           *merge_cp_length_p, name_ref_i, new_name_ref_i));

       }

       if (new_signature_ref_i == 0) {

         new_signature_ref_i = signature_ref_i;

       } else {

         RC_TRACE(0x00080000,

           ("NameAndType entry@%d signature_ref_index change: %d to %d",

           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));

       }

       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,

         new_name_ref_i, new_signature_ref_i);

       if (scratch_i != *merge_cp_length_p) {

         // The new entry in *merge_cp_p is at a different index than

         // the new entry in scratch_cp so we need to map the index values.

         map_index(scratch_cp, scratch_i, *merge_cp_length_p);

       }

       (*merge_cp_length_p)++;

     } break;

     // this is a double-indirect CP entry so it needs special handling

     case JVM_CONSTANT_Fieldref:           // fall through

     case JVM_CONSTANT_InterfaceMethodref: // fall through

     case JVM_CONSTANT_Methodref:

     {

       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);

       int new_klass_ref_i = 0;

       bool match = (klass_ref_i < *merge_cp_length_p) &&

         scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,

           THREAD);

       if (!match) {

         // forward reference in *merge_cp_p or not a direct match

         int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,

           THREAD);

         if (found_i != 0) {

           guarantee(found_i != klass_ref_i,

             "compare_entry_to() and find_matching_entry() do not agree");

           // Found a matching entry somewhere else in *merge_cp_p so

           // just need a mapping entry.

           new_klass_ref_i = found_i;

           map_index(scratch_cp, klass_ref_i, found_i);

         } else {

           // no match found so we have to append this entry to *merge_cp_p

           append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,

             THREAD);

           // The above call to append_entry() can only append one entry

           // so the post call query of *merge_cp_length_p is only for

           // the sake of consistency. Without the optimization where we

           // use JVM_CONSTANT_UnresolvedClass, then up to two entries

           // could be appended.

           new_klass_ref_i = *merge_cp_length_p - 1;

         }

       }

       int name_and_type_ref_i =

         scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);

       int new_name_and_type_ref_i = 0;

       match = (name_and_type_ref_i < *merge_cp_length_p) &&

         scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,

           name_and_type_ref_i, THREAD);

       if (!match) {

         // forward reference in *merge_cp_p or not a direct match

         int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,

           *merge_cp_p, THREAD);

         if (found_i != 0) {

           guarantee(found_i != name_and_type_ref_i,

             "compare_entry_to() and find_matching_entry() do not agree");

           // Found a matching entry somewhere else in *merge_cp_p so

           // just need a mapping entry.

           new_name_and_type_ref_i = found_i;

           map_index(scratch_cp, name_and_type_ref_i, found_i);

         } else {

           // no match found so we have to append this entry to *merge_cp_p

           append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,

             merge_cp_length_p, THREAD);

           // The above call to append_entry() can append more than

           // one entry so the post call query of *merge_cp_length_p

           // is required in order to get the right index for the

           // JVM_CONSTANT_NameAndType entry.

           new_name_and_type_ref_i = *merge_cp_length_p - 1;

         }

       }

       // If the referenced entries already exist in *merge_cp_p, then

       // both new_klass_ref_i and new_name_and_type_ref_i will both be

       // 0. In that case, all we are appending is the current entry.

       if (new_klass_ref_i == 0) {

         new_klass_ref_i = klass_ref_i;

       }

       if (new_name_and_type_ref_i == 0) {

         new_name_and_type_ref_i = name_and_type_ref_i;

       }

       const char *entry_name;

       switch (scratch_cp->tag_at(scratch_i).value()) {

       case JVM_CONSTANT_Fieldref:

         entry_name = "Fieldref";

         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,

           new_name_and_type_ref_i);

         break;

       case JVM_CONSTANT_InterfaceMethodref:

         entry_name = "IFMethodref";

         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,

           new_klass_ref_i, new_name_and_type_ref_i);

         break;

       case JVM_CONSTANT_Methodref:

         entry_name = "Methodref";

         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,

           new_name_and_type_ref_i);

         break;

       default:

         guarantee(false, "bad switch");

         break;

       }

       if (klass_ref_i != new_klass_ref_i) {

         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",

           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));

       }

       if (name_and_type_ref_i != new_name_and_type_ref_i) {

         RC_TRACE(0x00080000,

           ("%s entry@%d name_and_type_index changed: %d to %d",

           entry_name, *merge_cp_length_p, name_and_type_ref_i,

           new_name_and_type_ref_i));

       }

       if (scratch_i != *merge_cp_length_p) {

         // The new entry in *merge_cp_p is at a different index than

         // the new entry in scratch_cp so we need to map the index values.

         map_index(scratch_cp, scratch_i, *merge_cp_length_p);

       }

       (*merge_cp_length_p)++;

     } break;

     // At this stage, Class or UnresolvedClass could be here, but not

     // ClassIndex

     case JVM_CONSTANT_ClassIndex: // fall through

     // Invalid is used as the tag for the second constant pool entry

     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should

     // not be seen by itself.

     case JVM_CONSTANT_Invalid: // fall through

     // At this stage, String or UnresolvedString could be here, but not

     // StringIndex

     case JVM_CONSTANT_StringIndex: // fall through

     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be

     // here

     case JVM_CONSTANT_UnresolvedClassInError: // fall through

     default:

     {

       // leave a breadcrumb

       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();

       ShouldNotReachHere();

     } break;

   } // end switch tag value

 } // end append_entry()

 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {

   typeArrayOop save;

   save = scratch_class->get_method_annotations_of(i);

   scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));

   scratch_class->set_method_annotations_of(j, save);

   save = scratch_class->get_method_parameter_annotations_of(i);

   scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));

   scratch_class->set_method_parameter_annotations_of(j, save);

   save = scratch_class->get_method_default_annotations_of(i);

   scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));

   scratch_class->set_method_default_annotations_of(j, save);

 }

 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(

              instanceKlassHandle the_class,

              instanceKlassHandle scratch_class) {

   int i;

   // Check superclasses, or rather their names, since superclasses themselves can be

   // requested to replace.

   // Check for NULL superclass first since this might be java.lang.Object

   if (the_class->super() != scratch_class->super() &&

       (the_class->super() == NULL || scratch_class->super() == NULL ||

        Klass::cast(the_class->super())->name() !=

        Klass::cast(scratch_class->super())->name())) {

     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;

   }

   // Check if the number, names and order of directly implemented interfaces are the same.

   // I think in principle we should just check if the sets of names of directly implemented

   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the

   // .java file, also changes in .class file) should not matter. However, comparing sets is

   // technically a bit more difficult, and, more importantly, I am not sure at present that the

   // order of interfaces does not matter on the implementation level, i.e. that the VM does not

   // rely on it somewhere.

   objArrayOop k_interfaces = the_class->local_interfaces();

   objArrayOop k_new_interfaces = scratch_class->local_interfaces();

   int n_intfs = k_interfaces->length();

   if (n_intfs != k_new_interfaces->length()) {

     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;

   }

   for (i = 0; i < n_intfs; i++) {

     if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=

         Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;

     }

   }

   // Check whether class is in the error init state.

   if (the_class->is_in_error_state()) {

     // TBD #5057930: special error code is needed in 1.6

     return JVMTI_ERROR_INVALID_CLASS;

   }

   // Check whether class modifiers are the same.

   jushort old_flags = (jushort) the_class->access_flags().get_flags();

   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();

   if (old_flags != new_flags) {

     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;

   }

   // Check if the number, names, types and order of fields declared in these classes

   // are the same.

   typeArrayOop k_old_fields = the_class->fields();

   typeArrayOop k_new_fields = scratch_class->fields();

   int n_fields = k_old_fields->length();

   if (n_fields != k_new_fields->length()) {

     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

   }

   for (i = 0; i < n_fields; i += instanceKlass::next_offset) {

     // access

     old_flags = k_old_fields->ushort_at(i + instanceKlass::access_flags_offset);

     new_flags = k_new_fields->ushort_at(i + instanceKlass::access_flags_offset);

     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

     // offset

     if (k_old_fields->short_at(i + instanceKlass::low_offset) !=

         k_new_fields->short_at(i + instanceKlass::low_offset) ||

         k_old_fields->short_at(i + instanceKlass::high_offset) !=

         k_new_fields->short_at(i + instanceKlass::high_offset)) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

     // name and signature

     jshort name_index = k_old_fields->short_at(i + instanceKlass::name_index_offset);

     jshort sig_index = k_old_fields->short_at(i +instanceKlass::signature_index_offset);

     symbolOop name_sym1 = the_class->constants()->symbol_at(name_index);

     symbolOop sig_sym1 = the_class->constants()->symbol_at(sig_index);

     name_index = k_new_fields->short_at(i + instanceKlass::name_index_offset);

     sig_index = k_new_fields->short_at(i + instanceKlass::signature_index_offset);

     symbolOop name_sym2 = scratch_class->constants()->symbol_at(name_index);

     symbolOop sig_sym2 = scratch_class->constants()->symbol_at(sig_index);

     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

   }

   // Do a parallel walk through the old and new methods. Detect

   // cases where they match (exist in both), have been added in

   // the new methods, or have been deleted (exist only in the

   // old methods).  The class file parser places methods in order

   // by method name, but does not order overloaded methods by

   // signature.  In order to determine what fate befell the methods,

   // this code places the overloaded new methods that have matching

   // old methods in the same order as the old methods and places

   // new overloaded methods at the end of overloaded methods of

   // that name. The code for this order normalization is adapted

   // from the algorithm used in instanceKlass::find_method().

   // Since we are swapping out of order entries as we find them,

   // we only have to search forward through the overloaded methods.

   // Methods which are added and have the same name as an existing

   // method (but different signature) will be put at the end of

   // the methods with that name, and the name mismatch code will

   // handle them.

   objArrayHandle k_old_methods(the_class->methods());

   objArrayHandle k_new_methods(scratch_class->methods());

   int n_old_methods = k_old_methods->length();

   int n_new_methods = k_new_methods->length();

   int ni = 0;

   int oi = 0;

   while (true) {

     methodOop k_old_method;

     methodOop k_new_method;

     enum { matched, added, deleted, undetermined } method_was = undetermined;

     if (oi >= n_old_methods) {

       if (ni >= n_new_methods) {

         break; // we've looked at everything, done

       }

       // New method at the end

       k_new_method = (methodOop) k_new_methods->obj_at(ni);

       method_was = added;

     } else if (ni >= n_new_methods) {

       // Old method, at the end, is deleted

       k_old_method = (methodOop) k_old_methods->obj_at(oi);

       method_was = deleted;

     } else {

       // There are more methods in both the old and new lists

       k_old_method = (methodOop) k_old_methods->obj_at(oi);

       k_new_method = (methodOop) k_new_methods->obj_at(ni);

       if (k_old_method->name() != k_new_method->name()) {

         // Methods are sorted by method name, so a mismatch means added

         // or deleted

         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {

           method_was = added;

         } else {

           method_was = deleted;

         }

       } else if (k_old_method->signature() == k_new_method->signature()) {

         // Both the name and signature match

         method_was = matched;

       } else {

         // The name matches, but the signature doesn't, which means we have to

         // search forward through the new overloaded methods.

         int nj;  // outside the loop for post-loop check

         for (nj = ni + 1; nj < n_new_methods; nj++) {

           methodOop m = (methodOop)k_new_methods->obj_at(nj);

           if (k_old_method->name() != m->name()) {

             // reached another method name so no more overloaded methods

             method_was = deleted;

             break;

           }

           if (k_old_method->signature() == m->signature()) {

             // found a match so swap the methods

             k_new_methods->obj_at_put(ni, m);

             k_new_methods->obj_at_put(nj, k_new_method);

             k_new_method = m;

             method_was = matched;

             break;

           }

         }

         if (nj >= n_new_methods) {

           // reached the end without a match; so method was deleted

           method_was = deleted;

         }

       }

     }

     switch (method_was) {

     case matched:

       // methods match, be sure modifiers do too

       old_flags = (jushort) k_old_method->access_flags().get_flags();

       new_flags = (jushort) k_new_method->access_flags().get_flags();

       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {

         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;

       }

       {

         u2 new_num = k_new_method->method_idnum();

         u2 old_num = k_old_method->method_idnum();

         if (new_num != old_num) {

           methodOop idnum_owner = scratch_class->method_with_idnum(old_num);

           if (idnum_owner != NULL) {

             // There is already a method assigned this idnum -- switch them

             idnum_owner->set_method_idnum(new_num);

           }

           k_new_method->set_method_idnum(old_num);

           swap_all_method_annotations(old_num, new_num, scratch_class);

         }

       }

       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",

                             k_new_method->name_and_sig_as_C_string(), ni,

                             k_old_method->name_and_sig_as_C_string(), oi));

       // advance to next pair of methods

       ++oi;

       ++ni;

       break;

     case added:

       // method added, see if it is OK

       new_flags = (jushort) k_new_method->access_flags().get_flags();

       if ((new_flags & JVM_ACC_PRIVATE) == 0

            // hack: private should be treated as final, but alas

           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0

          ) {

         // new methods must be private

         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;

       }

       {

         u2 num = the_class->next_method_idnum();

         if (num == constMethodOopDesc::UNSET_IDNUM) {

           // cannot add any more methods

           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;

         }

         u2 new_num = k_new_method->method_idnum();

         methodOop idnum_owner = scratch_class->method_with_idnum(num);

         if (idnum_owner != NULL) {

           // There is already a method assigned this idnum -- switch them

           idnum_owner->set_method_idnum(new_num);

         }

         k_new_method->set_method_idnum(num);

         swap_all_method_annotations(new_num, num, scratch_class);

       }

       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",

                             k_new_method->name_and_sig_as_C_string(), ni));

       ++ni; // advance to next new method

       break;

     case deleted:

       // method deleted, see if it is OK

       old_flags = (jushort) k_old_method->access_flags().get_flags();

       if ((old_flags & JVM_ACC_PRIVATE) == 0

            // hack: private should be treated as final, but alas

           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0

          ) {

         // deleted methods must be private

         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;

       }

       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",

                             k_old_method->name_and_sig_as_C_string(), oi));

       ++oi; // advance to next old method

       break;

     default:

       ShouldNotReachHere();

     }

   }

   return JVMTI_ERROR_NONE;

 }

 // Find new constant pool index value for old constant pool index value

 // by seaching the index map. Returns zero (0) if there is no mapped

 // value for the old constant pool index.

 int VM_RedefineClasses::find_new_index(int old_index) {

   if (_index_map_count == 0) {

     // map is empty so nothing can be found

     return 0;

   }

   if (old_index < 1 || old_index >= _index_map_p->length()) {

     // The old_index is out of range so it is not mapped. This should

     // not happen in regular constant pool merging use, but it can

     // happen if a corrupt annotation is processed.

     return 0;

   }

   int value = _index_map_p->at(old_index);

   if (value == -1) {

     // the old_index is not mapped

     return 0;

   }

   return value;

 } // end find_new_index()

 // Returns true if the current mismatch is due to a resolved/unresolved

 // class pair. Otherwise, returns false.

 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,

        int index1, constantPoolHandle cp2, int index2) {

   jbyte t1 = cp1->tag_at(index1).value();

   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {

     return false;  // wrong entry type; not our special case

   }

   jbyte t2 = cp2->tag_at(index2).value();

   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {

     return false;  // wrong entry type; not our special case

   }

   if (t1 == t2) {

     return false;  // not a mismatch; not our special case

   }

   char *s1 = cp1->klass_name_at(index1)->as_C_string();

   char *s2 = cp2->klass_name_at(index2)->as_C_string();

   if (strcmp(s1, s2) != 0) {

     return false;  // strings don't match; not our special case

   }

   return true;  // made it through the gauntlet; this is our special case

 } // end is_unresolved_class_mismatch()

 // Returns true if the current mismatch is due to a resolved/unresolved

 // string pair. Otherwise, returns false.

 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,

        int index1, constantPoolHandle cp2, int index2) {

   jbyte t1 = cp1->tag_at(index1).value();

   if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {

     return false;  // wrong entry type; not our special case

   }

   jbyte t2 = cp2->tag_at(index2).value();

   if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {

     return false;  // wrong entry type; not our special case

   }

   if (t1 == t2) {

     return false;  // not a mismatch; not our special case

   }

   char *s1 = cp1->string_at_noresolve(index1);

   char *s2 = cp2->string_at_noresolve(index2);

   if (strcmp(s1, s2) != 0) {

     return false;  // strings don't match; not our special case

   }

   return true;  // made it through the gauntlet; this is our special case

 } // end is_unresolved_string_mismatch()

 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {

   // For consistency allocate memory using os::malloc wrapper.

   _scratch_classes = (instanceKlassHandle *)

     os::malloc(sizeof(instanceKlassHandle) * _class_count);

   if (_scratch_classes == NULL) {

     return JVMTI_ERROR_OUT_OF_MEMORY;

   }

   ResourceMark rm(THREAD);

   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());

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

     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);

     // classes for primitives cannot be redefined

     if (!is_modifiable_class(mirror)) {

       return JVMTI_ERROR_UNMODIFIABLE_CLASS;

     }

     klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);

     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);

     symbolHandle the_class_sym = symbolHandle(THREAD, the_class->name());

     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

     RC_TRACE_WITH_THREAD(0x00000001, THREAD,

       ("loading name=%s (avail_mem=" UINT64_FORMAT "K)",

       the_class->external_name(), os::available_memory() >> 10));

     ClassFileStream st((u1*) _class_defs[i].class_bytes,

       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");

     // Parse the stream.

     Handle the_class_loader(THREAD, the_class->class_loader());

     Handle protection_domain(THREAD, the_class->protection_domain());

     // Set redefined class handle in JvmtiThreadState class.

     // This redefined class is sent to agent event handler for class file

     // load hook event.

     state->set_class_being_redefined(&the_class, _class_load_kind);

     klassOop k = SystemDictionary::parse_stream(the_class_sym,

                                                 the_class_loader,

                                                 protection_domain,

                                                 &st,

                                                 THREAD);

     // Clear class_being_redefined just to be sure.

     state->clear_class_being_redefined();

     // TODO: if this is retransform, and nothing changed we can skip it

     instanceKlassHandle scratch_class (THREAD, k);

     if (HAS_PENDING_EXCEPTION) {

       symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();

       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",

         ex_name->as_C_string()));

       CLEAR_PENDING_EXCEPTION;

       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {

         return JVMTI_ERROR_UNSUPPORTED_VERSION;

       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {

         return JVMTI_ERROR_INVALID_CLASS_FORMAT;

       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {

         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;

       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {

         // The message will be "XXX (wrong name: YYY)"

         return JVMTI_ERROR_NAMES_DONT_MATCH;

       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {

         return JVMTI_ERROR_OUT_OF_MEMORY;

       } else {  // Just in case more exceptions can be thrown..

         return JVMTI_ERROR_FAILS_VERIFICATION;

       }

     }

     // Ensure class is linked before redefine

     if (!the_class->is_linked()) {

       the_class->link_class(THREAD);

       if (HAS_PENDING_EXCEPTION) {

         symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();

         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",

           ex_name->as_C_string()));

         CLEAR_PENDING_EXCEPTION;

         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {

           return JVMTI_ERROR_OUT_OF_MEMORY;

         } else {

           return JVMTI_ERROR_INTERNAL;

         }

       }

     }

     // Do the validity checks in compare_and_normalize_class_versions()

     // before verifying the byte codes. By doing these checks first, we

     // limit the number of functions that require redirection from

     // the_class to scratch_class. In particular, we don't have to

     // modify JNI GetSuperclass() and thus won't change its performance.

     jvmtiError res = compare_and_normalize_class_versions(the_class,

                        scratch_class);

     if (res != JVMTI_ERROR_NONE) {

       return res;

     }

     // verify what the caller passed us

     {

       // The bug 6214132 caused the verification to fail.

       // Information about the_class and scratch_class is temporarily

       // recorded into jvmtiThreadState. This data is used to redirect

       // the_class to scratch_class in the JVM_* functions called by the

       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed

       // description.

       RedefineVerifyMark rvm(&the_class, &scratch_class, state);

       Verifier::verify(

         scratch_class, Verifier::ThrowException, THREAD);

     }

     if (HAS_PENDING_EXCEPTION) {

       symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();

       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

       RC_TRACE_WITH_THREAD(0x00000002, THREAD,

         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));

       CLEAR_PENDING_EXCEPTION;

       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {

         return JVMTI_ERROR_OUT_OF_MEMORY;

       } else {

         // tell the caller the bytecodes are bad

         return JVMTI_ERROR_FAILS_VERIFICATION;

       }

     }

     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);

     if (res != JVMTI_ERROR_NONE) {

       return res;

     }

     if (VerifyMergedCPBytecodes) {

       // verify what we have done during constant pool merging

       {

         RedefineVerifyMark rvm(&the_class, &scratch_class, state);

         Verifier::verify(scratch_class, Verifier::ThrowException, THREAD);

       }

       if (HAS_PENDING_EXCEPTION) {

         symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();

         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

         RC_TRACE_WITH_THREAD(0x00000002, THREAD,

           ("verify_byte_codes post merge-CP exception: '%s'",

           ex_name->as_C_string()));

         CLEAR_PENDING_EXCEPTION;

         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {

           return JVMTI_ERROR_OUT_OF_MEMORY;

         } else {

           // tell the caller that constant pool merging screwed up

           return JVMTI_ERROR_INTERNAL;

         }

       }

     }

     Rewriter::rewrite(scratch_class, THREAD);

     if (HAS_PENDING_EXCEPTION) {

       symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();

       CLEAR_PENDING_EXCEPTION;

       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {

         return JVMTI_ERROR_OUT_OF_MEMORY;

       } else {

         return JVMTI_ERROR_INTERNAL;

       }

     }

     _scratch_classes[i] = scratch_class;

     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

     RC_TRACE_WITH_THREAD(0x00000001, THREAD,

       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",

       the_class->external_name(), os::available_memory() >> 10));

   }

   return JVMTI_ERROR_NONE;

 }

 // Map old_index to new_index as needed. scratch_cp is only needed

 // for RC_TRACE() calls.

 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,

        int old_index, int new_index) {

   if (find_new_index(old_index) != 0) {

     // old_index is already mapped

     return;

   }

   if (old_index == new_index) {

     // no mapping is needed

     return;

   }

   _index_map_p->at_put(old_index, new_index);

   _index_map_count++;

   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",

     scratch_cp->tag_at(old_index).value(), old_index, new_index));

 } // end map_index()

 // Merge old_cp and scratch_cp and return the results of the merge via

 // merge_cp_p. The number of entries in *merge_cp_p is returned via

 // merge_cp_length_p. The entries in old_cp occupy the same locations

 // in *merge_cp_p. Also creates a map of indices from entries in

 // scratch_cp to the corresponding entry in *merge_cp_p. Index map

 // entries are only created for entries in scratch_cp that occupy a

 // different location in *merged_cp_p.

 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,

        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,

        int *merge_cp_length_p, TRAPS) {

   if (merge_cp_p == NULL) {

     assert(false, "caller must provide scatch constantPool");

     return false; // robustness

   }

   if (merge_cp_length_p == NULL) {

     assert(false, "caller must provide scatch CP length");

     return false; // robustness

   }

   // Worst case we need old_cp->length() + scratch_cp()->length(),

   // but the caller might be smart so make sure we have at least

   // the minimum.

   if ((*merge_cp_p)->length() < old_cp->length()) {

     assert(false, "merge area too small");

     return false; // robustness

   }

   RC_TRACE_WITH_THREAD(0x00010000, THREAD,

     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),

     scratch_cp->length()));

   {

     // Pass 0:

     // The old_cp is copied to *merge_cp_p; this means that any code

     // using old_cp does not have to change. This work looks like a

     // perfect fit for constantPoolOop::copy_cp_to(), but we need to

     // handle one special case:

     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass

     // This will make verification happy.

     int old_i;  // index into old_cp

     // index zero (0) is not used in constantPools

     for (old_i = 1; old_i < old_cp->length(); old_i++) {

       // leave debugging crumb

       jbyte old_tag = old_cp->tag_at(old_i).value();

       switch (old_tag) {

       case JVM_CONSTANT_Class:

         // revert the copy to JVM_CONSTANT_UnresolvedClass

         (*merge_cp_p)->unresolved_klass_at_put(old_i,

           old_cp->klass_name_at(old_i));

         break;

       case JVM_CONSTANT_Double:

       case JVM_CONSTANT_Long:

         // just copy the entry to *merge_cp_p, but double and long take

         // two constant pool entries

         old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0);

         old_i++;

         break;

       default:

         // just copy the entry to *merge_cp_p

         old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0);

         break;

       }

     } // end for each old_cp entry

     // We don't need to sanity check that *merge_cp_length_p is within

     // *merge_cp_p bounds since we have the minimum on-entry check above.

     (*merge_cp_length_p) = old_i;

   }

   // merge_cp_len should be the same as old_cp->length() at this point

   // so this trace message is really a "warm-and-breathing" message.

   RC_TRACE_WITH_THREAD(0x00020000, THREAD,

     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));

   int scratch_i;  // index into scratch_cp

   {

     // Pass 1a:

     // Compare scratch_cp entries to the old_cp entries that we have

     // already copied to *merge_cp_p. In this pass, we are eliminating

     // exact duplicates (matching entry at same index) so we only

     // compare entries in the common indice range.

     int increment = 1;

     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());

     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {

       switch (scratch_cp->tag_at(scratch_i).value()) {

       case JVM_CONSTANT_Double:

       case JVM_CONSTANT_Long:

         // double and long take two constant pool entries

         increment = 2;

         break;

       default:

         increment = 1;

         break;

       }

       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,

         scratch_i, CHECK_0);

       if (match) {

         // found a match at the same index so nothing more to do

         continue;

       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,

                                               *merge_cp_p, scratch_i)) {

         // The mismatch in compare_entry_to() above is because of a

         // resolved versus unresolved class entry at the same index

         // with the same string value. Since Pass 0 reverted any

         // class entries to unresolved class entries in *merge_cp_p,

         // we go with the unresolved class entry.

         continue;

       } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,

                                                *merge_cp_p, scratch_i)) {

         // The mismatch in compare_entry_to() above is because of a

         // resolved versus unresolved string entry at the same index

         // with the same string value. We can live with whichever

         // happens to be at scratch_i in *merge_cp_p.

         continue;

       }

       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,

         CHECK_0);

       if (found_i != 0) {

         guarantee(found_i != scratch_i,

           "compare_entry_to() and find_matching_entry() do not agree");

         // Found a matching entry somewhere else in *merge_cp_p so

         // just need a mapping entry.

         map_index(scratch_cp, scratch_i, found_i);

         continue;

       }

       // The find_matching_entry() call above could fail to find a match

       // due to a resolved versus unresolved class or string entry situation

       // like we solved above with the is_unresolved_*_mismatch() calls.

       // However, we would have to call is_unresolved_*_mismatch() over

       // all of *merge_cp_p (potentially) and that doesn't seem to be

       // worth the time.

       // No match found so we have to append this entry and any unique

       // referenced entries to *merge_cp_p.

       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,

         CHECK_0);

     }

   }

   RC_TRACE_WITH_THREAD(0x00020000, THREAD,

     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",

     *merge_cp_length_p, scratch_i, _index_map_count));

   if (scratch_i < scratch_cp->length()) {

     // Pass 1b:

     // old_cp is smaller than scratch_cp so there are entries in

     // scratch_cp that we have not yet processed. We take care of

     // those now.

     int increment = 1;

     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {

       switch (scratch_cp->tag_at(scratch_i).value()) {

       case JVM_CONSTANT_Double:

       case JVM_CONSTANT_Long:

         // double and long take two constant pool entries

         increment = 2;

         break;

       default:

         increment = 1;

         break;

       }

       int found_i =

         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);

       if (found_i != 0) {

         // Found a matching entry somewhere else in *merge_cp_p so

         // just need a mapping entry.

         map_index(scratch_cp, scratch_i, found_i);

         continue;

       }

       // No match found so we have to append this entry and any unique

       // referenced entries to *merge_cp_p.

       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,

         CHECK_0);

     }

     RC_TRACE_WITH_THREAD(0x00020000, THREAD,

       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",

       *merge_cp_length_p, scratch_i, _index_map_count));

   }

   return true;

 } // end merge_constant_pools()

 // Merge constant pools between the_class and scratch_class and

 // potentially rewrite bytecodes in scratch_class to use the merged

 // constant pool.

 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(

              instanceKlassHandle the_class, instanceKlassHandle scratch_class,

              TRAPS) {

   // worst case merged constant pool length is old and new combined

   int merge_cp_length = the_class->constants()->length()

         + scratch_class->constants()->length();

   constantPoolHandle old_cp(THREAD, the_class->constants());

   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());

   // Constant pools are not easily reused so we allocate a new one

   // each time.

   // merge_cp is created unsafe for concurrent GC processing.  It

   // should be marked safe before discarding it because, even if

   // garbage.  If it crosses a card boundary, it may be scanned

   // in order to find the start of the first complete object on the card.

   constantPoolHandle merge_cp(THREAD,

     oopFactory::new_constantPool(merge_cp_length,

                                  methodOopDesc::IsUnsafeConc,

                                  THREAD));

   int orig_length = old_cp->orig_length();

   if (orig_length == 0) {

     // This old_cp is an actual original constant pool. We save

     // the original length in the merged constant pool so that

     // merge_constant_pools() can be more efficient. If a constant

     // pool has a non-zero orig_length() value, then that constant

     // pool was created by a merge operation in RedefineClasses.

     merge_cp->set_orig_length(old_cp->length());

   } else {

     // This old_cp is a merged constant pool from a previous

     // RedefineClasses() calls so just copy the orig_length()

     // value.

     merge_cp->set_orig_length(old_cp->orig_length());

   }

   ResourceMark rm(THREAD);

   _index_map_count = 0;

   _index_map_p = new intArray(scratch_cp->length(), -1);

   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,

                   &merge_cp_length, THREAD);

   if (!result) {

     // The merge can fail due to memory allocation failure or due

     // to robustness checks.

     return JVMTI_ERROR_INTERNAL;

   }

   RC_TRACE_WITH_THREAD(0x00010000, THREAD,

     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));

   if (_index_map_count == 0) {

     // there is nothing to map between the new and merged constant pools

     if (old_cp->length() == scratch_cp->length()) {

       // The old and new constant pools are the same length and the

       // index map is empty. This means that the three constant pools

       // are equivalent (but not the same). Unfortunately, the new

       // constant pool has not gone through link resolution nor have

       // the new class bytecodes gone through constant pool cache

       // rewriting so we can't use the old constant pool with the new

       // class.

       merge_cp()->set_is_conc_safe(true);

       merge_cp = constantPoolHandle();  // toss the merged constant pool

     } else if (old_cp->length() < scratch_cp->length()) {

       // The old constant pool has fewer entries than the new constant

       // pool and the index map is empty. This means the new constant

       // pool is a superset of the old constant pool. However, the old

       // class bytecodes have already gone through constant pool cache

       // rewriting so we can't use the new constant pool with the old

       // class.

       merge_cp()->set_is_conc_safe(true);

       merge_cp = constantPoolHandle();  // toss the merged constant pool

     } else {

       // The old constant pool has more entries than the new constant

       // pool and the index map is empty. This means that both the old

       // and merged constant pools are supersets of the new constant

       // pool.

       // Replace the new constant pool with a shrunken copy of the

       // merged constant pool; the previous new constant pool will

       // get GCed.

       set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,

         THREAD);

       // drop local ref to the merged constant pool

       merge_cp()->set_is_conc_safe(true);

       merge_cp = constantPoolHandle();

     }

   } else {

     if (RC_TRACE_ENABLED(0x00040000)) {

       // don't want to loop unless we are tracing

       int count = 0;

       for (int i = 1; i < _index_map_p->length(); i++) {

         int value = _index_map_p->at(i);

         if (value != -1) {

           RC_TRACE_WITH_THREAD(0x00040000, THREAD,

             ("index_map[%d]: old=%d new=%d", count, i, value));

           count++;

         }

       }

     }

     // We have entries mapped between the new and merged constant pools

     // so we have to rewrite some constant pool references.

     if (!rewrite_cp_refs(scratch_class, THREAD)) {

       return JVMTI_ERROR_INTERNAL;

     }

     // Replace the new constant pool with a shrunken copy of the

     // merged constant pool so now the rewritten bytecodes have

     // valid references; the previous new constant pool will get

     // GCed.

     set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,

       THREAD);

     merge_cp()->set_is_conc_safe(true);

   }

   assert(old_cp()->is_conc_safe(), "Just checking");

   assert(scratch_cp()->is_conc_safe(), "Just checking");

   return JVMTI_ERROR_NONE;

 } // end merge_cp_and_rewrite()

 // Rewrite constant pool references in klass scratch_class.

 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,

        TRAPS) {

   // rewrite constant pool references in the methods:

   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the class_annotations:

   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the fields_annotations:

   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the methods_annotations:

   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the methods_parameter_annotations:

   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,

          THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the methods_default_annotations:

   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,

          THREAD)) {

     // propagate failure back to caller

     return false;

   }

   return true;

 } // end rewrite_cp_refs()

 // Rewrite constant pool references in the methods.

 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(

        instanceKlassHandle scratch_class, TRAPS) {

   objArrayHandle methods(THREAD, scratch_class->methods());

   if (methods.is_null() || methods->length() == 0) {

     // no methods so nothing to do

     return true;

   }

   // rewrite constant pool references in the methods:

   for (int i = methods->length() - 1; i >= 0; i--) {

     methodHandle method(THREAD, (methodOop)methods->obj_at(i));

     methodHandle new_method;

     rewrite_cp_refs_in_method(method, &new_method, CHECK_false);

     if (!new_method.is_null()) {

       // the method has been replaced so save the new method version

       methods->obj_at_put(i, new_method());

     }

   }

   return true;

 }

 // Rewrite constant pool references in the specific method. This code

 // was adapted from Rewriter::rewrite_method().

 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,

        methodHandle *new_method_p, TRAPS) {

   *new_method_p = methodHandle();  // default is no new method

   // We cache a pointer to the bytecodes here in code_base. If GC

   // moves the methodOop, then the bytecodes will also move which

   // will likely cause a crash. We create a No_Safepoint_Verifier

   // object to detect whether we pass a possible safepoint in this

   // code block.

   No_Safepoint_Verifier nsv;

   // Bytecodes and their length

   address code_base = method->code_base();

   int code_length = method->code_size();

   int bc_length;

   for (int bci = 0; bci < code_length; bci += bc_length) {

     address bcp = code_base + bci;

     Bytecodes::Code c = (Bytecodes::Code)(*bcp);

     bc_length = Bytecodes::length_for(c);

     if (bc_length == 0) {

       // More complicated bytecodes report a length of zero so

       // we have to try again a slightly different way.

       bc_length = Bytecodes::length_at(bcp);

     }

     assert(bc_length != 0, "impossible bytecode length");

     switch (c) {

       case Bytecodes::_ldc:

       {

         int cp_index = *(bcp + 1);

         int new_index = find_new_index(cp_index);

         if (StressLdcRewrite && new_index == 0) {

           // If we are stressing ldc -> ldc_w rewriting, then we

           // always need a new_index value.

           new_index = cp_index;

         }

         if (new_index != 0) {

           // the original index is mapped so we have more work to do

           if (!StressLdcRewrite && new_index <= max_jubyte) {

             // The new value can still use ldc instead of ldc_w

             // unless we are trying to stress ldc -> ldc_w rewriting

             RC_TRACE_WITH_THREAD(0x00080000, THREAD,

               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),

               bcp, cp_index, new_index));

             *(bcp + 1) = new_index;

           } else {

             RC_TRACE_WITH_THREAD(0x00080000, THREAD,

               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",

               Bytecodes::name(c), bcp, cp_index, new_index));

             // the new value needs ldc_w instead of ldc

             u_char inst_buffer[4]; // max instruction size is 4 bytes

             bcp = (address)inst_buffer;

             // construct new instruction sequence

             *bcp = Bytecodes::_ldc_w;

             bcp++;

             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.

             // See comment below for difference between put_Java_u2()

             // and put_native_u2().

             Bytes::put_Java_u2(bcp, new_index);

             Relocator rc(method, NULL /* no RelocatorListener needed */);

             methodHandle m;

             {

               Pause_No_Safepoint_Verifier pnsv(&nsv);

               // ldc is 2 bytes and ldc_w is 3 bytes

               m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);

               if (m.is_null() || HAS_PENDING_EXCEPTION) {

                 guarantee(false, "insert_space_at() failed");

               }

             }

             // return the new method so that the caller can update

             // the containing class

             *new_method_p = method = m;

             // switch our bytecode processing loop from the old method

             // to the new method

             code_base = method->code_base();

             code_length = method->code_size();

             bcp = code_base + bci;

             c = (Bytecodes::Code)(*bcp);

             bc_length = Bytecodes::length_for(c);

             assert(bc_length != 0, "sanity check");

           } // end we need ldc_w instead of ldc

         } // end if there is a mapped index

       } break;

       // these bytecodes have a two-byte constant pool index

       case Bytecodes::_anewarray      : // fall through

       case Bytecodes::_checkcast      : // fall through

       case Bytecodes::_getfield       : // fall through

       case Bytecodes::_getstatic      : // fall through

       case Bytecodes::_instanceof     : // fall through

       case Bytecodes::_invokeinterface: // fall through

       case Bytecodes::_invokespecial  : // fall through

       case Bytecodes::_invokestatic   : // fall through

       case Bytecodes::_invokevirtual  : // fall through

       case Bytecodes::_ldc_w          : // fall through

       case Bytecodes::_ldc2_w         : // fall through

       case Bytecodes::_multianewarray : // fall through

       case Bytecodes::_new            : // fall through

       case Bytecodes::_putfield       : // fall through

       case Bytecodes::_putstatic      :

       {

         address p = bcp + 1;

         int cp_index = Bytes::get_Java_u2(p);

         int new_index = find_new_index(cp_index);

         if (new_index != 0) {

           // the original index is mapped so update w/ new value

           RC_TRACE_WITH_THREAD(0x00080000, THREAD,

             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),

             bcp, cp_index, new_index));

           // Rewriter::rewrite_method() uses put_native_u2() in this

           // situation because it is reusing the constant pool index

           // location for a native index into the constantPoolCache.

           // Since we are updating the constant pool index prior to

           // verification and constantPoolCache initialization, we

           // need to keep the new index in Java byte order.

           Bytes::put_Java_u2(p, new_index);

         }

       } break;

     }

   } // end for each bytecode

 } // end rewrite_cp_refs_in_method()

 // Rewrite constant pool references in the class_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   typeArrayHandle class_annotations(THREAD,

     scratch_class->class_annotations());

   if (class_annotations.is_null() || class_annotations->length() == 0) {

     // no class_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("class_annotations length=%d", class_annotations->length()));

   int byte_i = 0;  // byte index into class_annotations

   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,

            THREAD);

 }

 // Rewrite constant pool references in an annotations typeArray. This

 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute

 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:

 //

 // annotations_typeArray {

 //   u2 num_annotations;

 //   annotation annotations[num_annotations];

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(

        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {

   if ((byte_i_ref + 2) > annotations_typeArray->length()) {

     // not enough room for num_annotations field

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("length() is too small for num_annotations field"));

     return false;

   }

   u2 num_annotations = Bytes::get_Java_u2((address)

                          annotations_typeArray->byte_at_addr(byte_i_ref));

   byte_i_ref += 2;

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("num_annotations=%d", num_annotations));

   int calc_num_annotations = 0;

   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {

     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,

            byte_i_ref, THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("bad annotation_struct at %d", calc_num_annotations));

       // propagate failure back to caller

       return false;

     }

   }

   assert(num_annotations == calc_num_annotations, "sanity check");

   return true;

 } // end rewrite_cp_refs_in_annotations_typeArray()

 // Rewrite constant pool references in the annotation struct portion of

 // an annotations_typeArray. This "structure" is from section 4.8.15 of

 // the 2nd-edition of the VM spec:

 //

 // struct annotation {

 //   u2 type_index;

 //   u2 num_element_value_pairs;

 //   {

 //     u2 element_name_index;

 //     element_value value;

 //   } element_value_pairs[num_element_value_pairs];

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(

        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {

   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {

     // not enough room for smallest annotation_struct

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("length() is too small for annotation_struct"));

     return false;

   }

   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,

                     byte_i_ref, "mapped old type_index=%d", THREAD);

   u2 num_element_value_pairs = Bytes::get_Java_u2((address)

                                  annotations_typeArray->byte_at_addr(

                                  byte_i_ref));

   byte_i_ref += 2;

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("type_index=%d  num_element_value_pairs=%d", type_index,

     num_element_value_pairs));

   int calc_num_element_value_pairs = 0;

   for (; calc_num_element_value_pairs < num_element_value_pairs;

        calc_num_element_value_pairs++) {

     if ((byte_i_ref + 2) > annotations_typeArray->length()) {

       // not enough room for another element_name_index, let alone

       // the rest of another component

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("length() is too small for element_name_index"));

       return false;

     }

     u2 element_name_index = rewrite_cp_ref_in_annotation_data(

                               annotations_typeArray, byte_i_ref,

                               "mapped old element_name_index=%d", THREAD);

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("element_name_index=%d", element_name_index));

     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,

            byte_i_ref, THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("bad element_value at %d", calc_num_element_value_pairs));

       // propagate failure back to caller

       return false;

     }

   } // end for each component

   assert(num_element_value_pairs == calc_num_element_value_pairs,

     "sanity check");

   return true;

 } // end rewrite_cp_refs_in_annotation_struct()

 // Rewrite a constant pool reference at the current position in

 // annotations_typeArray if needed. Returns the original constant

 // pool reference if a rewrite was not needed or the new constant

 // pool reference if a rewrite was needed.

 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(

      typeArrayHandle annotations_typeArray, int &byte_i_ref,

      const char * trace_mesg, TRAPS) {

   address cp_index_addr = (address)

     annotations_typeArray->byte_at_addr(byte_i_ref);

   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);

   u2 new_cp_index = find_new_index(old_cp_index);

   if (new_cp_index != 0) {

     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));

     Bytes::put_Java_u2(cp_index_addr, new_cp_index);

     old_cp_index = new_cp_index;

   }

   byte_i_ref += 2;

   return old_cp_index;

 }

 // Rewrite constant pool references in the element_value portion of an

 // annotations_typeArray. This "structure" is from section 4.8.15.1 of

 // the 2nd-edition of the VM spec:

 //

 // struct element_value {

 //   u1 tag;

 //   union {

 //     u2 const_value_index;

 //     {

 //       u2 type_name_index;

 //       u2 const_name_index;

 //     } enum_const_value;

 //     u2 class_info_index;

 //     annotation annotation_value;

 //     struct {

 //       u2 num_values;

 //       element_value values[num_values];

 //     } array_value;

 //   } value;

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(

        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {

   if ((byte_i_ref + 1) > annotations_typeArray->length()) {

     // not enough room for a tag let alone the rest of an element_value

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("length() is too small for a tag"));

     return false;

   }

   u1 tag = annotations_typeArray->byte_at(byte_i_ref);

   byte_i_ref++;

   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));

   switch (tag) {

     // These BaseType tag values are from Table 4.2 in VM spec:

     case 'B':  // byte

     case 'C':  // char

     case 'D':  // double

     case 'F':  // float

     case 'I':  // int

     case 'J':  // long

     case 'S':  // short

     case 'Z':  // boolean

     // The remaining tag values are from Table 4.8 in the 2nd-edition of

     // the VM spec:

     case 's':

     {

       // For the above tag values (including the BaseType values),

       // value.const_value_index is right union field.

       if ((byte_i_ref + 2) > annotations_typeArray->length()) {

         // not enough room for a const_value_index

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

           ("length() is too small for a const_value_index"));

         return false;

       }

       u2 const_value_index = rewrite_cp_ref_in_annotation_data(

                                annotations_typeArray, byte_i_ref,

                                "mapped old const_value_index=%d", THREAD);

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("const_value_index=%d", const_value_index));

     } break;

     case 'e':

     {

       // for the above tag value, value.enum_const_value is right union field

       if ((byte_i_ref + 4) > annotations_typeArray->length()) {

         // not enough room for a enum_const_value

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

           ("length() is too small for a enum_const_value"));

         return false;

       }

       u2 type_name_index = rewrite_cp_ref_in_annotation_data(

                              annotations_typeArray, byte_i_ref,

                              "mapped old type_name_index=%d", THREAD);

       u2 const_name_index = rewrite_cp_ref_in_annotation_data(

                               annotations_typeArray, byte_i_ref,

                               "mapped old const_name_index=%d", THREAD);

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("type_name_index=%d  const_name_index=%d", type_name_index,

         const_name_index));

     } break;

     case 'c':

     {

       // for the above tag value, value.class_info_index is right union field

       if ((byte_i_ref + 2) > annotations_typeArray->length()) {

         // not enough room for a class_info_index

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

           ("length() is too small for a class_info_index"));

         return false;

       }

       u2 class_info_index = rewrite_cp_ref_in_annotation_data(

                               annotations_typeArray, byte_i_ref,

                               "mapped old class_info_index=%d", THREAD);

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("class_info_index=%d", class_info_index));

     } break;

     case '@':

       // For the above tag value, value.attr_value is the right union

       // field. This is a nested annotation.

       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,

              byte_i_ref, THREAD)) {

         // propagate failure back to caller

         return false;

       }

       break;

     case '[':

     {

       if ((byte_i_ref + 2) > annotations_typeArray->length()) {

         // not enough room for a num_values field

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

           ("length() is too small for a num_values field"));

         return false;

       }

       // For the above tag value, value.array_value is the right union

       // field. This is an array of nested element_value.

       u2 num_values = Bytes::get_Java_u2((address)

                         annotations_typeArray->byte_at_addr(byte_i_ref));

       byte_i_ref += 2;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));

       int calc_num_values = 0;

       for (; calc_num_values < num_values; calc_num_values++) {

         if (!rewrite_cp_refs_in_element_value(

                annotations_typeArray, byte_i_ref, THREAD)) {

           RC_TRACE_WITH_THREAD(0x02000000, THREAD,

             ("bad nested element_value at %d", calc_num_values));

           // propagate failure back to caller

           return false;

         }

       }

       assert(num_values == calc_num_values, "sanity check");

     } break;

     default:

       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));

       return false;

   } // end decode tag field

   return true;

 } // end rewrite_cp_refs_in_element_value()

 // Rewrite constant pool references in a fields_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   objArrayHandle fields_annotations(THREAD,

     scratch_class->fields_annotations());

   if (fields_annotations.is_null() || fields_annotations->length() == 0) {

     // no fields_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("fields_annotations length=%d", fields_annotations->length()));

   for (int i = 0; i < fields_annotations->length(); i++) {

     typeArrayHandle field_annotations(THREAD,

       (typeArrayOop)fields_annotations->obj_at(i));

     if (field_annotations.is_null() || field_annotations->length() == 0) {

       // this field does not have any annotations so skip it

       continue;

     }

     int byte_i = 0;  // byte index into field_annotations

     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,

            THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("bad field_annotations at %d", i));

       // propagate failure back to caller

       return false;

     }

   }

   return true;

 } // end rewrite_cp_refs_in_fields_annotations()

 // Rewrite constant pool references in a methods_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   objArrayHandle methods_annotations(THREAD,

     scratch_class->methods_annotations());

   if (methods_annotations.is_null() || methods_annotations->length() == 0) {

     // no methods_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("methods_annotations length=%d", methods_annotations->length()));

   for (int i = 0; i < methods_annotations->length(); i++) {

     typeArrayHandle method_annotations(THREAD,

       (typeArrayOop)methods_annotations->obj_at(i));

     if (method_annotations.is_null() || method_annotations->length() == 0) {

       // this method does not have any annotations so skip it

       continue;

     }

     int byte_i = 0;  // byte index into method_annotations

     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,

            THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("bad method_annotations at %d", i));

       // propagate failure back to caller

       return false;

     }

   }

   return true;

 } // end rewrite_cp_refs_in_methods_annotations()

 // Rewrite constant pool references in a methods_parameter_annotations

 // field. This "structure" is adapted from the

 // RuntimeVisibleParameterAnnotations_attribute described in section

 // 4.8.17 of the 2nd-edition of the VM spec:

 //

 // methods_parameter_annotations_typeArray {

 //   u1 num_parameters;

 //   {

 //     u2 num_annotations;

 //     annotation annotations[num_annotations];

 //   } parameter_annotations[num_parameters];

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   objArrayHandle methods_parameter_annotations(THREAD,

     scratch_class->methods_parameter_annotations());

   if (methods_parameter_annotations.is_null()

       || methods_parameter_annotations->length() == 0) {

     // no methods_parameter_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("methods_parameter_annotations length=%d",

     methods_parameter_annotations->length()));

   for (int i = 0; i < methods_parameter_annotations->length(); i++) {

     typeArrayHandle method_parameter_annotations(THREAD,

       (typeArrayOop)methods_parameter_annotations->obj_at(i));

     if (method_parameter_annotations.is_null()

         || method_parameter_annotations->length() == 0) {

       // this method does not have any parameter annotations so skip it

       continue;

     }

     if (method_parameter_annotations->length() < 1) {

       // not enough room for a num_parameters field

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("length() is too small for a num_parameters field at %d", i));

       return false;

     }

     int byte_i = 0;  // byte index into method_parameter_annotations

     u1 num_parameters = method_parameter_annotations->byte_at(byte_i);

     byte_i++;

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("num_parameters=%d", num_parameters));

     int calc_num_parameters = 0;

     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {

       if (!rewrite_cp_refs_in_annotations_typeArray(

              method_parameter_annotations, byte_i, THREAD)) {

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

           ("bad method_parameter_annotations at %d", calc_num_parameters));

         // propagate failure back to caller

         return false;

       }

     }

     assert(num_parameters == calc_num_parameters, "sanity check");

   }

   return true;

 } // end rewrite_cp_refs_in_methods_parameter_annotations()

 // Rewrite constant pool references in a methods_default_annotations

 // field. This "structure" is adapted from the AnnotationDefault_attribute

 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:

 //

 // methods_default_annotations_typeArray {

 //   element_value default_value;

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   objArrayHandle methods_default_annotations(THREAD,

     scratch_class->methods_default_annotations());

   if (methods_default_annotations.is_null()

       || methods_default_annotations->length() == 0) {

     // no methods_default_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

     ("methods_default_annotations length=%d",

     methods_default_annotations->length()));

   for (int i = 0; i < methods_default_annotations->length(); i++) {

     typeArrayHandle method_default_annotations(THREAD,

       (typeArrayOop)methods_default_annotations->obj_at(i));

     if (method_default_annotations.is_null()

         || method_default_annotations->length() == 0) {

       // this method does not have any default annotations so skip it

       continue;

     }

     int byte_i = 0;  // byte index into method_default_annotations

     if (!rewrite_cp_refs_in_element_value(

            method_default_annotations, byte_i, THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("bad default element_value at %d", i));

       // propagate failure back to caller

       return false;

     }

   }

   return true;

 } // end rewrite_cp_refs_in_methods_default_annotations()

 // Rewrite constant pool references in the method's stackmap table.

 // These "structures" are adapted from the StackMapTable_attribute that

 // is described in section 4.8.4 of the 6.0 version of the VM spec

 // (dated 2005.10.26):

 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf

 //

 // stack_map {

 //   u2 number_of_entries;

 //   stack_map_frame entries[number_of_entries];

 // }

 //

 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(

        methodHandle method, TRAPS) {

   if (!method->has_stackmap_table()) {

     return;

   }

   typeArrayOop stackmap_data = method->stackmap_data();

   address stackmap_p = (address)stackmap_data->byte_at_addr(0);

   address stackmap_end = stackmap_p + stackmap_data->length();

   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");

   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);

   stackmap_p += 2;

   RC_TRACE_WITH_THREAD(0x04000000, THREAD,

     ("number_of_entries=%u", number_of_entries));

   // walk through each stack_map_frame

   u2 calc_number_of_entries = 0;

   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {

     // The stack_map_frame structure is a u1 frame_type followed by

     // 0 or more bytes of data:

     //

     // union stack_map_frame {

     //   same_frame;

     //   same_locals_1_stack_item_frame;

     //   same_locals_1_stack_item_frame_extended;

     //   chop_frame;

     //   same_frame_extended;

     //   append_frame;

     //   full_frame;

     // }

     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");

     // The Linux compiler does not like frame_type to be u1 or u2. It

     // issues the following warning for the first if-statement below:

     //

     // "warning: comparison is always true due to limited range of data type"

     //

     u4 frame_type = *stackmap_p;

     stackmap_p++;

     // same_frame {

     //   u1 frame_type = SAME; /* 0-63 */

     // }

     if (frame_type >= 0 && frame_type <= 63) {

       // nothing more to do for same_frame

     }

     // same_locals_1_stack_item_frame {

     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */

     //   verification_type_info stack[1];

     // }

     else if (frame_type >= 64 && frame_type <= 127) {

       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,

         calc_number_of_entries, frame_type, THREAD);

     }

     // reserved for future use

     else if (frame_type >= 128 && frame_type <= 246) {

       // nothing more to do for reserved frame_types

     }

     // same_locals_1_stack_item_frame_extended {

     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */

     //   u2 offset_delta;

     //   verification_type_info stack[1];

     // }

     else if (frame_type == 247) {

       stackmap_p += 2;

       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,

         calc_number_of_entries, frame_type, THREAD);

     }

     // chop_frame {

     //   u1 frame_type = CHOP; /* 248-250 */

     //   u2 offset_delta;

     // }

     else if (frame_type >= 248 && frame_type <= 250) {

       stackmap_p += 2;

     }

     // same_frame_extended {

     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/

     //   u2 offset_delta;

     // }

     else if (frame_type == 251) {

       stackmap_p += 2;

     }

     // append_frame {

     //   u1 frame_type = APPEND; /* 252-254 */

     //   u2 offset_delta;

     //   verification_type_info locals[frame_type - 251];

     // }

     else if (frame_type >= 252 && frame_type <= 254) {

       assert(stackmap_p + 2 <= stackmap_end,

         "no room for offset_delta");

       stackmap_p += 2;

       u1 len = frame_type - 251;

       for (u1 i = 0; i < len; i++) {

         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,

           calc_number_of_entries, frame_type, THREAD);

       }

     }

     // full_frame {

     //   u1 frame_type = FULL_FRAME; /* 255 */

     //   u2 offset_delta;

     //   u2 number_of_locals;

     //   verification_type_info locals[number_of_locals];

     //   u2 number_of_stack_items;

     //   verification_type_info stack[number_of_stack_items];

     // }

     else if (frame_type == 255) {

       assert(stackmap_p + 2 + 2 <= stackmap_end,

         "no room for smallest full_frame");

       stackmap_p += 2;

       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);

       stackmap_p += 2;

       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {

         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,

           calc_number_of_entries, frame_type, THREAD);

       }

       // Use the largest size for the number_of_stack_items, but only get

       // the right number of bytes.

       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);

       stackmap_p += 2;

       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {

         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,

           calc_number_of_entries, frame_type, THREAD);

       }

     }

   } // end while there is a stack_map_frame

   assert(number_of_entries == calc_number_of_entries, "sanity check");

 } // end rewrite_cp_refs_in_stack_map_table()

 // Rewrite constant pool references in the verification type info

 // portion of the method's stackmap table. These "structures" are

 // adapted from the StackMapTable_attribute that is described in

 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):

 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf

 //

 // The verification_type_info structure is a u1 tag followed by 0 or

 // more bytes of data:

 //

 // union verification_type_info {

 //   Top_variable_info;

 //   Integer_variable_info;

 //   Float_variable_info;

 //   Long_variable_info;

 //   Double_variable_info;

 //   Null_variable_info;

 //   UninitializedThis_variable_info;

 //   Object_variable_info;

 //   Uninitialized_variable_info;

 // }

 //

 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(

        address& stackmap_p_ref, address stackmap_end, u2 frame_i,

        u1 frame_type, TRAPS) {

   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");

   u1 tag = *stackmap_p_ref;

   stackmap_p_ref++;

   switch (tag) {

   // Top_variable_info {

   //   u1 tag = ITEM_Top; /* 0 */

   // }

   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top

   case 0:  // fall through

   // Integer_variable_info {

   //   u1 tag = ITEM_Integer; /* 1 */

   // }

   case ITEM_Integer:  // fall through

   // Float_variable_info {

   //   u1 tag = ITEM_Float; /* 2 */

   // }

   case ITEM_Float:  // fall through

   // Double_variable_info {

   //   u1 tag = ITEM_Double; /* 3 */

   // }

   case ITEM_Double:  // fall through

   // Long_variable_info {

   //   u1 tag = ITEM_Long; /* 4 */

   // }

   case ITEM_Long:  // fall through

   // Null_variable_info {

   //   u1 tag = ITEM_Null; /* 5 */

   // }

   case ITEM_Null:  // fall through

   // UninitializedThis_variable_info {

   //   u1 tag = ITEM_UninitializedThis; /* 6 */

   // }

   case ITEM_UninitializedThis:

     // nothing more to do for the above tag types

     break;

   // Object_variable_info {

   //   u1 tag = ITEM_Object; /* 7 */

   //   u2 cpool_index;

   // }

   case ITEM_Object:

   {

     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");

     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);

     u2 new_cp_index = find_new_index(cpool_index);

     if (new_cp_index != 0) {

       RC_TRACE_WITH_THREAD(0x04000000, THREAD,

         ("mapped old cpool_index=%d", cpool_index));

       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);

       cpool_index = new_cp_index;

     }

     stackmap_p_ref += 2;

     RC_TRACE_WITH_THREAD(0x04000000, THREAD,

       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,

       frame_type, cpool_index));

   } break;

   // Uninitialized_variable_info {

   //   u1 tag = ITEM_Uninitialized; /* 8 */

   //   u2 offset;

   // }

   case ITEM_Uninitialized:

     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");

     stackmap_p_ref += 2;

     break;

   default:

     RC_TRACE_WITH_THREAD(0x04000000, THREAD,

       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));

     ShouldNotReachHere();

     break;

   } // end switch (tag)

 } // end rewrite_cp_refs_in_verification_type_info()

 // Change the constant pool associated with klass scratch_class to

 // scratch_cp. If shrink is true, then scratch_cp_length elements

 // are copied from scratch_cp to a smaller constant pool and the

 // smaller constant pool is associated with scratch_class.

 void VM_RedefineClasses::set_new_constant_pool(

        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,

        int scratch_cp_length, bool shrink, TRAPS) {

   assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");

   if (shrink) {

     // scratch_cp is a merged constant pool and has enough space for a

     // worst case merge situation. We want to associate the minimum

     // sized constant pool with the klass to save space.

     constantPoolHandle smaller_cp(THREAD,

       oopFactory::new_constantPool(scratch_cp_length,

                                    methodOopDesc::IsUnsafeConc,

                                    THREAD));

     // preserve orig_length() value in the smaller copy

     int orig_length = scratch_cp->orig_length();

     assert(orig_length != 0, "sanity check");

     smaller_cp->set_orig_length(orig_length);

     scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);

     scratch_cp = smaller_cp;

     smaller_cp()->set_is_conc_safe(true);

   }

   // attach new constant pool to klass

   scratch_cp->set_pool_holder(scratch_class());

   // attach klass to new constant pool

   scratch_class->set_constants(scratch_cp());

   int i;  // for portability

   // update each field in klass to use new constant pool indices as needed

   typeArrayHandle fields(THREAD, scratch_class->fields());

   int n_fields = fields->length();

   for (i = 0; i < n_fields; i += instanceKlass::next_offset) {

     jshort cur_index = fields->short_at(i + instanceKlass::name_index_offset);

     jshort new_index = find_new_index(cur_index);

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("field-name_index change: %d to %d", cur_index, new_index));

       fields->short_at_put(i + instanceKlass::name_index_offset, new_index);

     }

     cur_index = fields->short_at(i + instanceKlass::signature_index_offset);

     new_index = find_new_index(cur_index);

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("field-signature_index change: %d to %d", cur_index, new_index));

       fields->short_at_put(i + instanceKlass::signature_index_offset,

         new_index);

     }

     cur_index = fields->short_at(i + instanceKlass::initval_index_offset);

     new_index = find_new_index(cur_index);

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("field-initval_index change: %d to %d", cur_index, new_index));

       fields->short_at_put(i + instanceKlass::initval_index_offset, new_index);

     }

     cur_index = fields->short_at(i + instanceKlass::generic_signature_offset);

     new_index = find_new_index(cur_index);

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("field-generic_signature change: %d to %d", cur_index, new_index));

       fields->short_at_put(i + instanceKlass::generic_signature_offset,

         new_index);

     }

   } // end for each field

   // Update constant pool indices in the inner classes info to use

   // new constant indices as needed. The inner classes info is a

   // quadruple:

   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)

   typeArrayOop inner_class_list = scratch_class->inner_classes();

   int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();

   if (icl_length > 0) {

     typeArrayHandle inner_class_list_h(THREAD, inner_class_list);

     for (int i = 0; i < icl_length;

          i += instanceKlass::inner_class_next_offset) {

       int cur_index = inner_class_list_h->ushort_at(i

                         + instanceKlass::inner_class_inner_class_info_offset);

       if (cur_index == 0) {

         continue;  // JVM spec. allows null inner class refs so skip it

       }

       int new_index = find_new_index(cur_index);

       if (new_index != 0) {

         RC_TRACE_WITH_THREAD(0x00080000, THREAD,

           ("inner_class_info change: %d to %d", cur_index, new_index));

         inner_class_list_h->ushort_at_put(i

           + instanceKlass::inner_class_inner_class_info_offset, new_index);

       }

       cur_index = inner_class_list_h->ushort_at(i

                     + instanceKlass::inner_class_outer_class_info_offset);

       new_index = find_new_index(cur_index);

       if (new_index != 0) {

         RC_TRACE_WITH_THREAD(0x00080000, THREAD,

           ("outer_class_info change: %d to %d", cur_index, new_index));

         inner_class_list_h->ushort_at_put(i

           + instanceKlass::inner_class_outer_class_info_offset, new_index);

       }

       cur_index = inner_class_list_h->ushort_at(i

                     + instanceKlass::inner_class_inner_name_offset);

       new_index = find_new_index(cur_index);

       if (new_index != 0) {

         RC_TRACE_WITH_THREAD(0x00080000, THREAD,

           ("inner_name change: %d to %d", cur_index, new_index));

         inner_class_list_h->ushort_at_put(i

           + instanceKlass::inner_class_inner_name_offset, new_index);

       }

     } // end for each inner class

   } // end if we have inner classes

   // Attach each method in klass to the new constant pool and update

   // to use new constant pool indices as needed:

   objArrayHandle methods(THREAD, scratch_class->methods());

   for (i = methods->length() - 1; i >= 0; i--) {

     methodHandle method(THREAD, (methodOop)methods->obj_at(i));

     method->set_constants(scratch_cp());

     int new_index = find_new_index(method->name_index());

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("method-name_index change: %d to %d", method->name_index(),

         new_index));

       method->set_name_index(new_index);

     }

     new_index = find_new_index(method->signature_index());

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("method-signature_index change: %d to %d",

         method->signature_index(), new_index));

       method->set_signature_index(new_index);

     }

     new_index = find_new_index(method->generic_signature_index());

     if (new_index != 0) {

       RC_TRACE_WITH_THREAD(0x00080000, THREAD,

         ("method-generic_signature_index change: %d to %d",

         method->generic_signature_index(), new_index));

       method->set_generic_signature_index(new_index);

     }

     // Update constant pool indices in the method's checked exception

     // table to use new constant indices as needed.

     int cext_length = method->checked_exceptions_length();

     if (cext_length > 0) {

       CheckedExceptionElement * cext_table =

         method->checked_exceptions_start();

       for (int j = 0; j < cext_length; j++) {

         int cur_index = cext_table[j].class_cp_index;

         int new_index = find_new_index(cur_index);

         if (new_index != 0) {

           RC_TRACE_WITH_THREAD(0x00080000, THREAD,

             ("cext-class_cp_index change: %d to %d", cur_index, new_index));

           cext_table[j].class_cp_index = (u2)new_index;

         }

       } // end for each checked exception table entry

     } // end if there are checked exception table entries

     // Update each catch type index in the method's exception table

     // to use new constant pool indices as needed. The exception table

     // holds quadruple entries of the form:

     //   (beg_bci, end_bci, handler_bci, klass_index)

     const int beg_bci_offset     = 0;

     const int end_bci_offset     = 1;

     const int handler_bci_offset = 2;

     const int klass_index_offset = 3;

     const int entry_size         = 4;

     typeArrayHandle ex_table (THREAD, method->exception_table());

     int ext_length = ex_table->length();

     assert(ext_length % entry_size == 0, "exception table format has changed");

     for (int j = 0; j < ext_length; j += entry_size) {

       int cur_index = ex_table->int_at(j + klass_index_offset);

       int new_index = find_new_index(cur_index);

       if (new_index != 0) {

         RC_TRACE_WITH_THREAD(0x00080000, THREAD,

           ("ext-klass_index change: %d to %d", cur_index, new_index));

         ex_table->int_at_put(j + klass_index_offset, new_index);

       }

     } // end for each exception table entry

     // Update constant pool indices in the method's local variable

     // table to use new constant indices as needed. The local variable

     // table hold sextuple entries of the form:

     // (start_pc, length, name_index, descriptor_index, signature_index, slot)

     int lvt_length = method->localvariable_table_length();

     if (lvt_length > 0) {

       LocalVariableTableElement * lv_table =

         method->localvariable_table_start();

       for (int j = 0; j < lvt_length; j++) {

         int cur_index = lv_table[j].name_cp_index;

         int new_index = find_new_index(cur_index);

         if (new_index != 0) {

           RC_TRACE_WITH_THREAD(0x00080000, THREAD,

             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));

           lv_table[j].name_cp_index = (u2)new_index;

         }

         cur_index = lv_table[j].descriptor_cp_index;

         new_index = find_new_index(cur_index);

         if (new_index != 0) {

           RC_TRACE_WITH_THREAD(0x00080000, THREAD,

             ("lvt-descriptor_cp_index change: %d to %d", cur_index,

             new_index));

           lv_table[j].descriptor_cp_index = (u2)new_index;

         }

         cur_index = lv_table[j].signature_cp_index;

         new_index = find_new_index(cur_index);

         if (new_index != 0) {

           RC_TRACE_WITH_THREAD(0x00080000, THREAD,

             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));

           lv_table[j].signature_cp_index = (u2)new_index;

         }

       } // end for each local variable table entry

     } // end if there are local variable table entries

     rewrite_cp_refs_in_stack_map_table(method, THREAD);

   } // end for each method

   assert(scratch_cp()->is_conc_safe(), "Just checking");

 } // end set_new_constant_pool()

 // Unevolving classes may point to methods of the_class directly

 // from their constant pool caches, itables, and/or vtables. We

 // use the SystemDictionary::classes_do() facility and this helper

 // to fix up these pointers.

 //

 // Note: We currently don't support updating the vtable in

 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.

 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,

        oop initiating_loader, TRAPS) {

   Klass *k = k_oop->klass_part();

   if (k->oop_is_instance()) {

     HandleMark hm(THREAD);

     instanceKlass *ik = (instanceKlass *) k;

     // HotSpot specific optimization! HotSpot does not currently

     // support delegation from the bootstrap class loader to a

     // user-defined class loader. This means that if the bootstrap

     // class loader is the initiating class loader, then it will also

     // be the defining class loader. This also means that classes

     // loaded by the bootstrap class loader cannot refer to classes

     // loaded by a user-defined class loader. Note: a user-defined

     // class loader can delegate to the bootstrap class loader.

     //

     // If the current class being redefined has a user-defined class

     // loader as its defining class loader, then we can skip all

     // classes loaded by the bootstrap class loader.

     bool is_user_defined =

            instanceKlass::cast(_the_class_oop)->class_loader() != NULL;

     if (is_user_defined && ik->class_loader() == NULL) {

       return;

     }

     // This is a very busy routine. We don't want too much tracing

     // printed out.

     bool trace_name_printed = false;

     // Very noisy: only enable this call if you are trying to determine

     // that a specific class gets found by this routine.

     // RC_TRACE macro has an embedded ResourceMark

     // RC_TRACE_WITH_THREAD(0x00100000, THREAD,

     //   ("adjust check: name=%s", ik->external_name()));

     // trace_name_printed = true;

     // Fix the vtable embedded in the_class and subclasses of the_class,

     // if one exists. We discard scratch_class and we don't keep an

     // instanceKlass around to hold obsolete methods so we don't have

     // any other instanceKlass embedded vtables to update. The vtable

     // holds the methodOops for virtual (but not final) methods.

     if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {

       // ik->vtable() creates a wrapper object; rm cleans it up

       ResourceMark rm(THREAD);

       ik->vtable()->adjust_method_entries(_matching_old_methods,

                                           _matching_new_methods,

                                           _matching_methods_length,

                                           &trace_name_printed);

     }

     // If the current class has an itable and we are either redefining an

     // interface or if the current class is a subclass of the_class, then

     // we potentially have to fix the itable. If we are redefining an

     // interface, then we have to call adjust_method_entries() for

     // every instanceKlass that has an itable since there isn't a

     // subclass relationship between an interface and an instanceKlass.

     if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()

         || ik->is_subclass_of(_the_class_oop))) {

       // ik->itable() creates a wrapper object; rm cleans it up

       ResourceMark rm(THREAD);

       ik->itable()->adjust_method_entries(_matching_old_methods,

                                           _matching_new_methods,

                                           _matching_methods_length,

                                           &trace_name_printed);

     }

     // The constant pools in other classes (other_cp) can refer to

     // methods in the_class. We have to update method information in

     // other_cp's cache. If other_cp has a previous version, then we

     // have to repeat the process for each previous version. The

     // constant pool cache holds the methodOops for non-virtual

     // methods and for virtual, final methods.

     //

     // Special case: if the current class is the_class, then new_cp

     // has already been attached to the_class and old_cp has already

     // been added as a previous version. The new_cp doesn't have any

     // cached references to old methods so it doesn't need to be

     // updated. We can simply start with the previous version(s) in

     // that case.

     constantPoolHandle other_cp;

     constantPoolCacheOop cp_cache;

     if (k_oop != _the_class_oop) {

       // this klass' constant pool cache may need adjustment

       other_cp = constantPoolHandle(ik->constants());

       cp_cache = other_cp->cache();

       if (cp_cache != NULL) {

         cp_cache->adjust_method_entries(_matching_old_methods,

                                         _matching_new_methods,

                                         _matching_methods_length,

                                         &trace_name_printed);

       }

     }

     {

       ResourceMark rm(THREAD);

       // PreviousVersionInfo objects returned via PreviousVersionWalker

       // contain a GrowableArray of handles. We have to clean up the

       // GrowableArray _after_ the PreviousVersionWalker destructor

       // has destroyed the handles.

       {