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

 /*

  * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "classfile/metadataOnStackMark.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "classfile/verifier.hpp"

 #include "code/codeCache.hpp"

 #include "compiler/compileBroker.hpp"

 #include "interpreter/oopMapCache.hpp"

 #include "interpreter/rewriter.hpp"

 #include "memory/gcLocker.hpp"

 #include "memory/metadataFactory.hpp"

 #include "memory/metaspaceShared.hpp"

 #include "memory/universe.inline.hpp"

 #include "oops/fieldStreams.hpp"

 #include "oops/klassVtable.hpp"

 #include "prims/jvmtiImpl.hpp"

 #include "prims/jvmtiRedefineClasses.hpp"

 #include "prims/methodComparator.hpp"

 #include "runtime/deoptimization.hpp"

 #include "runtime/relocator.hpp"

 #include "utilities/bitMap.inline.hpp"

 #include "utilities/events.hpp"

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;

 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;

 Method**  VM_RedefineClasses::_matching_old_methods = NULL;

 Method**  VM_RedefineClasses::_matching_new_methods = NULL;

 Method**  VM_RedefineClasses::_deleted_methods      = NULL;

 Method**  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;

 Klass*      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 any successfully created classes, since none are redefined

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

       if (_scratch_classes[i] != NULL) {

         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();

         // Free the memory for this class at class unloading time.  Not before

         // because CMS might think this is still live.

         cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);

       }

     }

     // 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 (!MetaspaceShared::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;

     }

   }

   // Mark methods seen on stack and everywhere else so old methods are not

   // cleaned up if they're on the stack.

   MetadataOnStackMark md_on_stack(true);

   HandleMark hm(thread);   // make sure any handles created are deleted

                            // before the stack walk again.

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

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

     ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();

     // Free the memory for this class at class unloading time.  Not before

     // because CMS might think this is still live.

     cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);

     _scratch_classes[i] = NULL;

   }

   // 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();

 // check_class() is optionally called for product bits, but is

 // always called for non-product bits.

 #ifdef PRODUCT

   if (RC_TRACE_ENABLED(0x00004000)) {

 #endif

     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));

     CheckClass check_class(thread);

     ClassLoaderDataGraph::classes_do(&check_class);

 #ifdef PRODUCT

   }

 #endif

 }

 void VM_RedefineClasses::doit_epilogue() {

   // Free os::malloc allocated memory.

   os::free(_scratch_classes);

   // Reset the_class_oop to null for error printing.

   _the_class_oop = NULL;

   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;

   }

   Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);

   // classes for arrays cannot be redefined

   if (the_class_oop == NULL || !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:

     {

       ConstantPool::copy_entry_to(scratch_cp, 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

     // Symbol*s so this entry can be directly appended.

     case JVM_CONSTANT_String:      // fall through

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

     // Symbol*s so these entries can be directly appended.

     case JVM_CONSTANT_UnresolvedClass:  // fall through

     {

       ConstantPool::copy_entry_to(scratch_cp, 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 = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,

                                                          merge_cp_length_p, THREAD);

       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);

       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,

                                                               merge_cp_p, merge_cp_length_p,

                                                               THREAD);

       // 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 != name_ref_i) {

         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 != signature_ref_i) {

         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 = find_or_append_indirect_entry(scratch_cp, klass_ref_i,

                                                           merge_cp_p, merge_cp_length_p, THREAD);

       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);

       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,

                                                           merge_cp_p, merge_cp_length_p, THREAD);

       const char *entry_name = NULL;

       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;

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

     case JVM_CONSTANT_MethodType:

     {

       int ref_i = scratch_cp->method_type_index_at(scratch_i);

       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,

                                                     merge_cp_length_p, THREAD);

       if (new_ref_i != ref_i) {

         RC_TRACE(0x00080000,

                  ("MethodType entry@%d ref_index change: %d to %d",

                   *merge_cp_length_p, ref_i, new_ref_i));

       }

       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_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 an indirect CP entry so it needs special handling

     case JVM_CONSTANT_MethodHandle:

     {

       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);

       int ref_i = scratch_cp->method_handle_index_at(scratch_i);

       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,

                                                     merge_cp_length_p, THREAD);

       if (new_ref_i != ref_i) {

         RC_TRACE(0x00080000,

                  ("MethodHandle entry@%d ref_index change: %d to %d",

                   *merge_cp_length_p, ref_i, new_ref_i));

       }

       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_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 an indirect CP entry so it needs special handling

     case JVM_CONSTANT_InvokeDynamic:

     {

       // Index of the bootstrap specifier in the operands array

       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);

       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,

                                             merge_cp_length_p, THREAD);

       // The bootstrap method NameAndType_info index

       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);

       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,

                                                     merge_cp_length_p, THREAD);

       if (new_bs_i != old_bs_i) {

         RC_TRACE(0x00080000,

                  ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",

                   *merge_cp_length_p, old_bs_i, new_bs_i));

       }

       if (new_ref_i != old_ref_i) {

         RC_TRACE(0x00080000,

                  ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",

                   *merge_cp_length_p, old_ref_i, new_ref_i));

       }

       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_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 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()

 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,

       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {

   int new_ref_i = ref_i;

   bool match = (ref_i < *merge_cp_length_p) &&

                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);

   if (!match) {

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

     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);

     if (found_i != 0) {

       guarantee(found_i != 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_ref_i = found_i;

       map_index(scratch_cp, ref_i, found_i);

     } else {

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

       append_entry(scratch_cp, 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_ref_i = *merge_cp_length_p - 1;

     }

   }

   return new_ref_i;

 } // end find_or_append_indirect_entry()

 // Append a bootstrap specifier into the merge_cp operands that is semantically equal

 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.

 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.

 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,

        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {

   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);

   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,

                                                 merge_cp_length_p, THREAD);

   if (new_ref_i != old_ref_i) {

     RC_TRACE(0x00080000,

              ("operands entry@%d bootstrap method ref_index change: %d to %d",

               _operands_cur_length, old_ref_i, new_ref_i));

   }

   Array<u2>* merge_ops = (*merge_cp_p)->operands();

   int new_bs_i = _operands_cur_length;

   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.

   // However, the operand_offset_at(0) was set in the extend_operands() call.

   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)

                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);

   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);

   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);

   merge_ops->at_put(new_base++, new_ref_i);

   merge_ops->at_put(new_base++, argc);

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

     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);

     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,

                                                       merge_cp_length_p, THREAD);

     merge_ops->at_put(new_base++, new_arg_ref_i);

     if (new_arg_ref_i != old_arg_ref_i) {

       RC_TRACE(0x00080000,

                ("operands entry@%d bootstrap method argument ref_index change: %d to %d",

                 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));

     }

   }

   if (old_bs_i != _operands_cur_length) {

     // The bootstrap specifier in *merge_cp_p is at a different index than

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

     map_operand_index(old_bs_i, new_bs_i);

   }

   _operands_cur_length++;

 } // end append_operand()

 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,

       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {

   int new_bs_i = old_bs_i; // bootstrap specifier index

   bool match = (old_bs_i < _operands_cur_length) &&

                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);

   if (!match) {

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

     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,

                                                     _operands_cur_length, THREAD);

     if (found_i != -1) {

       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");

       // found a matching operand somewhere else in *merge_cp_p so just need a mapping

       new_bs_i = found_i;

       map_operand_index(old_bs_i, found_i);

     } else {

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

       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);

       new_bs_i = _operands_cur_length - 1;

     }

   }

   return new_bs_i;

 } // end find_or_append_operand()

 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {

   if (merge_cp->operands() == NULL) {

     return;

   }

   // Shrink the merge_cp operands

   merge_cp->shrink_operands(_operands_cur_length, CHECK);

   if (RC_TRACE_ENABLED(0x00040000)) {

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

     int count = 0;

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

       int value = _operands_index_map_p->at(i);

       if (value != -1) {

         RC_TRACE_WITH_THREAD(0x00040000, THREAD,

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

         count++;

       }

     }

   }

   // Clean-up

   _operands_index_map_p = NULL;

   _operands_cur_length = 0;

   _operands_index_map_count = 0;

 } // end finalize_operands_merge()

 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 ||

        the_class->super()->name() !=

        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.

   Array<Klass*>* k_interfaces = the_class->local_interfaces();

   Array<Klass*>* 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 (k_interfaces->at(i)->name() !=

         k_new_interfaces->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.

   JavaFieldStream old_fs(the_class);

   JavaFieldStream new_fs(scratch_class);

   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {

     // access

     old_flags = old_fs.access_flags().as_short();

     new_flags = new_fs.access_flags().as_short();

     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

     // offset

     if (old_fs.offset() != new_fs.offset()) {

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

     // name and signature

     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());

     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());

     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());

     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());

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

       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;

     }

   }

   // If both streams aren't done then we have a differing number of

   // fields.

   if (!old_fs.done() || !new_fs.done()) {

     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.

   Array<Method*>* k_old_methods(the_class->methods());

   Array<Method*>* k_new_methods(scratch_class->methods());

   int n_old_methods = k_old_methods->length();

   int n_new_methods = k_new_methods->length();

   Thread* thread = Thread::current();

   int ni = 0;

   int oi = 0;

   while (true) {

     Method* k_old_method;

     Method* 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 = k_new_methods->at(ni);

       method_was = added;

     } else if (ni >= n_new_methods) {

       // Old method, at the end, is deleted

       k_old_method = k_old_methods->at(oi);

       method_was = deleted;

     } else {

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

       k_old_method = k_old_methods->at(oi);

       k_new_method = k_new_methods->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++) {

           Method* m = k_new_methods->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->at_put(ni, m);

             k_new_methods->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) {

           Method* idnum_owner = scratch_class->method_with_idnum(old_num);

           if (idnum_owner != NULL) {

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

             // Take current and original idnum from the new_method

             idnum_owner->set_method_idnum(new_num);

             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());

           }

           // Take current and original idnum from the old_method

           k_new_method->set_method_idnum(old_num);

           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());

           if (thread->has_pending_exception()) {

             return JVMTI_ERROR_OUT_OF_MEMORY;

           }

         }

       }

       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 == ConstMethod::UNSET_IDNUM) {

           // cannot add any more methods

           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;

         }

         u2 new_num = k_new_method->method_idnum();

         Method* idnum_owner = scratch_class->method_with_idnum(num);

         if (idnum_owner != NULL) {

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

           // Take current and original idnum from the new_method

           idnum_owner->set_method_idnum(new_num);

           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());

         }

         k_new_method->set_method_idnum(num);

         k_new_method->set_orig_method_idnum(num);

         if (thread->has_pending_exception()) {

           return JVMTI_ERROR_OUT_OF_MEMORY;

         }

       }

       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()

 // Find new bootstrap specifier index value for old bootstrap specifier index

 // value by seaching the index map. Returns unused index (-1) if there is

 // no mapped value for the old bootstrap specifier index.

 int VM_RedefineClasses::find_new_operand_index(int old_index) {

   if (_operands_index_map_count == 0) {

     // map is empty so nothing can be found

     return -1;

   }

   if (old_index == -1 || old_index >= _operands_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.

     return -1;

   }

   int value = _operands_index_map_p->at(old_index);

   if (value == -1) {

     // the old_index is not mapped

     return -1;

   }

   return value;

 } // end find_new_operand_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()

 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {

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

   _scratch_classes = (Klass**)

     os::malloc(sizeof(Klass*) * _class_count, mtClass);

   if (_scratch_classes == NULL) {

     return JVMTI_ERROR_OUT_OF_MEMORY;

   }

   // Zero initialize the _scratch_classes array.

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

     _scratch_classes[i] = NULL;

   }

   ResourceMark rm(THREAD);

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

   // state can only be NULL if the current thread is exiting which

   // should not happen since we're trying to do a RedefineClasses

   guarantee(state != NULL, "exiting thread calling load_new_class_versions");

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

     // Create HandleMark so that any handles created while loading new class

     // versions are deleted. Constant pools are deallocated while merging

     // constant pools

     HandleMark hm(THREAD);

     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;

     }

     Klass* the_class_oop = java_lang_Class::as_Klass(mirror);

     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);

     Symbol*  the_class_sym = the_class->name();

     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

     RC_TRACE_WITH_THREAD(0x00000001, THREAD,

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

       the_class->external_name(), _class_load_kind,

       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);

     Klass* 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);

     // Need to clean up allocated InstanceKlass if there's an error so assign

     // the result here. Caller deallocates all the scratch classes in case of

     // an error.

     _scratch_classes[i] = k;

     if (HAS_PENDING_EXCEPTION) {

       Symbol* ex_name = PENDING_EXCEPTION->klass()->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) {

         Symbol* ex_name = PENDING_EXCEPTION->klass()->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, true, THREAD);

     }

     if (HAS_PENDING_EXCEPTION) {

       Symbol* ex_name = PENDING_EXCEPTION->klass()->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 (HAS_PENDING_EXCEPTION) {

       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();

       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

       RC_TRACE_WITH_THREAD(0x00000002, THREAD,

         ("merge_cp_and_rewrite 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;

       }

     }

     if (VerifyMergedCPBytecodes) {

       // verify what we have done during constant pool merging

       {

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

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

       }

       if (HAS_PENDING_EXCEPTION) {

         Symbol* ex_name = PENDING_EXCEPTION->klass()->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) {

       scratch_class->link_methods(THREAD);

     }

     if (HAS_PENDING_EXCEPTION) {

       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();

       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

       RC_TRACE_WITH_THREAD(0x00000002, THREAD,

         ("Rewriter::rewrite or link_methods 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;

       }

     }

     // 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()

 // Map old_index to new_index as needed.

 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {

   if (find_new_operand_index(old_index) != -1) {

     // old_index is already mapped

     return;

   }

   if (old_index == new_index) {

     // no mapping is needed

     return;

   }

   _operands_index_map_p->at_put(old_index, new_index);

   _operands_index_map_count++;

   RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", 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 scratch constantPool");

     return false; // robustness

   }

   if (merge_cp_length_p == NULL) {

     assert(false, "caller must provide scratch 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 ConstantPool*::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:

       case JVM_CONSTANT_UnresolvedClass:

         // revert the copy to JVM_CONSTANT_UnresolvedClass

         // May be resolving while calling this so do the same for

         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)

         (*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

         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);

         old_i++;

         break;

       default:

         // just copy the entry to *merge_cp_p

         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);

         break;

       }

     } // end for each old_cp entry

     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);

     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);

     // 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;

       }

       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));

   }

   finalize_operands_merge(*merge_cp_p, THREAD);

   return true;

 } // end merge_constant_pools()

 // Scoped object to clean up the constant pool(s) created for merging

 class MergeCPCleaner {

   ClassLoaderData*   _loader_data;

   ConstantPool*      _cp;

   ConstantPool*      _scratch_cp;

  public:

   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :

                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}

   ~MergeCPCleaner() {

     _loader_data->add_to_deallocate_list(_cp);

     if (_scratch_cp != NULL) {

       _loader_data->add_to_deallocate_list(_scratch_cp);

     }

   }

   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }

 };

 // 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();

   // 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. Even though

   // 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.

   ClassLoaderData* loader_data = the_class->class_loader_data();

   ConstantPool* merge_cp_oop =

     ConstantPool::allocate(loader_data,

                            merge_cp_length,

                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));

   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);

   HandleMark hm(THREAD);  // make sure handles are cleared before

                           // MergeCPCleaner clears out merge_cp_oop

   constantPoolHandle merge_cp(THREAD, merge_cp_oop);

   // Get constants() from the old class because it could have been rewritten

   // while we were at a safepoint allocating a new constant pool.

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

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

   // If the length changed, the class was redefined out from under us. Return

   // an error.

   if (merge_cp_length != the_class->constants()->length()

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

     return JVMTI_ERROR_INTERNAL;

   }

   // Update the version number of the constant pool

   merge_cp->increment_and_save_version(old_cp->version());

   ResourceMark rm(THREAD);

   _index_map_count = 0;

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

   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());

   _operands_index_map_count = 0;

   _operands_index_map_p = new intArray(

     ConstantPool::operand_array_length(scratch_cp->operands()), -1);

   // reference to the cp holder is needed for copy_operands()

   merge_cp->set_pool_holder(scratch_class());

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

                   &merge_cp_length, THREAD);

   merge_cp->set_pool_holder(NULL);

   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.

       // toss the merged constant pool at return

     } 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.

       // toss the merged constant pool at return

     } 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

       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,

                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));

       // The new constant pool replaces scratch_cp so have cleaner clean it up.

       // It can't be cleaned up while there are handles to it.

       cp_cleaner.add_scratch_cp(scratch_cp());

     }

   } 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(loader_data, scratch_class, merge_cp, merge_cp_length,

                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));

     // The new constant pool replaces scratch_cp so have cleaner clean it up.

     // It can't be cleaned up while there are handles to it.

     cp_cleaner.add_scratch_cp(scratch_cp());

   }

   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;

   }

   // rewrite constant pool references in the class_type_annotations:

   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the fields_type_annotations:

   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // rewrite constant pool references in the methods_type_annotations:

   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {

     // propagate failure back to caller

     return false;

   }

   // There can be type annotations in the Code part of a method_info attribute.

   // These annotations are not accessible, even by reflection.

   // Currently they are not even parsed by the ClassFileParser.

   // If runtime access is added they will also need to be rewritten.

   // rewrite source file name index:

   u2 source_file_name_idx = scratch_class->source_file_name_index();

   if (source_file_name_idx != 0) {

     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);

     if (new_source_file_name_idx != 0) {

       scratch_class->set_source_file_name_index(new_source_file_name_idx);

     }

   }

   // rewrite class generic signature index:

   u2 generic_signature_index = scratch_class->generic_signature_index();

   if (generic_signature_index != 0) {

     u2 new_generic_signature_index = find_new_index(generic_signature_index);

     if (new_generic_signature_index != 0) {

       scratch_class->set_generic_signature_index(new_generic_signature_index);

     }

   }

   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) {

   Array<Method*>* methods = scratch_class->methods();

   if (methods == 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, methods->at(i));

     methodHandle new_method;

     rewrite_cp_refs_in_method(method, &new_method, THREAD);

     if (!new_method.is_null()) {

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

       // even in the case of an exception.  original method is on the

       // deallocation list.

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

     }

     if (HAS_PENDING_EXCEPTION) {

       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();

       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark

       RC_TRACE_WITH_THREAD(0x00000002, THREAD,

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

       // Need to clear pending exception here as the super caller sets

       // the JVMTI_ERROR_INTERNAL if the returned value is false.

       CLEAR_PENDING_EXCEPTION;

       return false;

     }

   }

   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 Method*, 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(method(), 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, CHECK);

             }

             // 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::_invokedynamic  : // 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

   // We also need to rewrite the parameter name indexes, if there is

   // method parameter data present

   if(method->has_method_parameters()) {

     const int len = method->method_parameters_length();

     MethodParametersElement* elem = method->method_parameters_start();

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

       const u2 cp_index = elem[i].name_cp_index;

       const u2 new_cp_index = find_new_index(cp_index);

       if (new_cp_index != 0) {

         elem[i].name_cp_index = new_cp_index;

       }

     }

   }

 } // 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) {

   AnnotationArray* class_annotations = scratch_class->class_annotations();

   if (class_annotations == 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(

        AnnotationArray* 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->adr_at(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(

        AnnotationArray* 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->adr_at(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.

 PRAGMA_DIAG_PUSH

 PRAGMA_FORMAT_NONLITERAL_IGNORED

 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(

      AnnotationArray* annotations_typeArray, int &byte_i_ref,

      const char * trace_mesg, TRAPS) {

   address cp_index_addr = (address)

     annotations_typeArray->adr_at(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;

 }

 PRAGMA_DIAG_POP

 // 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(

        AnnotationArray* 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->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->adr_at(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) {

   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();

   if (fields_annotations == 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++) {

     AnnotationArray* field_annotations = fields_annotations->at(i);

     if (field_annotations == 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) {

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

     Method* m = scratch_class->methods()->at(i);

     AnnotationArray* method_annotations = m->constMethod()->method_annotations();

     if (method_annotations == 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) {

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

     Method* m = scratch_class->methods()->at(i);

     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();

     if (method_parameter_annotations == 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->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) {

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

     Method* m = scratch_class->methods()->at(i);

     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();

     if (method_default_annotations == 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 a class_type_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();

   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {

     // no class_type_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

   int byte_i = 0;  // byte index into class_type_annotations

   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,

       byte_i, "ClassFile", THREAD);

 } // end rewrite_cp_refs_in_class_type_annotations()

 // Rewrite constant pool references in a fields_type_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();

   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {

     // no fields_type_annotations so nothing to do

     return true;

   }

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

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

     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);

     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {

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

       continue;

     }

     int byte_i = 0;  // byte index into field_type_annotations

     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,

            byte_i, "field_info", THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

       // propagate failure back to caller

       return false;

     }

   }

   return true;

 } // end rewrite_cp_refs_in_fields_type_annotations()

 // Rewrite constant pool references in a methods_type_annotations field.

 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(

        instanceKlassHandle scratch_class, TRAPS) {

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

     Method* m = scratch_class->methods()->at(i);

     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();

     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {

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

       continue;

     }

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("methods type_annotations length=%d", method_type_annotations->length()));

     int byte_i = 0;  // byte index into method_type_annotations

     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,

            byte_i, "method_info", THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

       // propagate failure back to caller

       return false;

     }

   }

   return true;

 } // end rewrite_cp_refs_in_methods_type_annotations()

 // Rewrite constant pool references in a type_annotations

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

 // RuntimeVisibleTypeAnnotations_attribute described in

 // section 4.7.20 of the Java SE 8 Edition of the VM spec:

 //

 // type_annotations_typeArray {

 //   u2              num_annotations;

 //   type_annotation annotations[num_annotations];

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(

        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,

        const char * location_mesg, TRAPS) {

   if ((byte_i_ref + 2) > type_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)

                          type_annotations_typeArray->adr_at(byte_i_ref));

   byte_i_ref += 2;

   RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

   int calc_num_annotations = 0;

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

     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,

            byte_i_ref, location_mesg, THREAD)) {

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

       // propagate failure back to caller

       return false;

     }

   }

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

   if (byte_i_ref != type_annotations_typeArray->length()) {

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

       ("read wrong amount of bytes at end of processing "

        "type_annotations_typeArray (%d of %d bytes were read)",

        byte_i_ref, type_annotations_typeArray->length()));

     return false;

   }

   return true;

 } // end rewrite_cp_refs_in_type_annotations_typeArray()

 // Rewrite constant pool references in a type_annotation

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

 // RuntimeVisibleTypeAnnotations_attribute described in

 // section 4.7.20 of the Java SE 8 Edition of the VM spec:

 //

 // type_annotation {

 //   u1 target_type;

 //   union {

 //     type_parameter_target;

 //     supertype_target;

 //     type_parameter_bound_target;

 //     empty_target;

 //     method_formal_parameter_target;

 //     throws_target;

 //     localvar_target;

 //     catch_target;

 //     offset_target;

 //     type_argument_target;

 //   } target_info;

 //   type_path target_path;

 //   annotation anno;

 // }

 //

 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(

        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,

        const char * location_mesg, TRAPS) {

   if (!skip_type_annotation_target(type_annotations_typeArray,

          byte_i_ref, location_mesg, THREAD)) {

     return false;

   }

   if (!skip_type_annotation_type_path(type_annotations_typeArray,

          byte_i_ref, THREAD)) {

     return false;

   }

   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,

          byte_i_ref, THREAD)) {

     return false;

   }

   return true;

 } // end rewrite_cp_refs_in_type_annotation_struct()

 // Read, verify and skip over the target_type and target_info part

 // so that rewriting can continue in the later parts of the struct.

 //

 // u1 target_type;

 // union {

 //   type_parameter_target;

 //   supertype_target;

 //   type_parameter_bound_target;

 //   empty_target;

 //   method_formal_parameter_target;

 //   throws_target;

 //   localvar_target;

 //   catch_target;

 //   offset_target;

 //   type_argument_target;

 // } target_info;

 //

 bool VM_RedefineClasses::skip_type_annotation_target(

        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,

        const char * location_mesg, TRAPS) {

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

     // not enough room for a target_type let alone the rest of a type_annotation

     RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

     return false;

   }

   u1 target_type = type_annotations_typeArray->at(byte_i_ref);

   byte_i_ref += 1;

   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("target_type=0x%.2x", target_type));

   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("location=%s", location_mesg));

   // Skip over target_info

   switch (target_type) {

     case 0x00:

     // kind: type parameter declaration of generic class or interface

     // location: ClassFile

     case 0x01:

     // kind: type parameter declaration of generic method or constructor

     // location: method_info

     {

       // struct:

       // type_parameter_target {

       //   u1 type_parameter_index;

       // }

       //

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

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

         return false;

       }

       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);

       byte_i_ref += 1;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("type_parameter_target: type_parameter_index=%d",

          type_parameter_index));

     } break;

     case 0x10:

     // kind: type in extends clause of class or interface declaration

     //       (including the direct superclass of an anonymous class declaration),

     //       or in implements clause of interface declaration

     // location: ClassFile

     {

       // struct:

       // supertype_target {

       //   u2 supertype_index;

       // }

       //

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

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

         return false;

       }

       u2 supertype_index = Bytes::get_Java_u2((address)

                              type_annotations_typeArray->adr_at(byte_i_ref));

       byte_i_ref += 2;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("supertype_target: supertype_index=%d", supertype_index));

     } break;

     case 0x11:

     // kind: type in bound of type parameter declaration of generic class or interface

     // location: ClassFile

     case 0x12:

     // kind: type in bound of type parameter declaration of generic method or constructor

     // location: method_info

     {

       // struct:

       // type_parameter_bound_target {

       //   u1 type_parameter_index;

       //   u1 bound_index;

       // }

       //

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

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

         return false;

       }

       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);

       byte_i_ref += 1;

       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);

       byte_i_ref += 1;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d",

          type_parameter_index, bound_index));

     } break;

     case 0x13:

     // kind: type in field declaration

     // location: field_info

     case 0x14:

     // kind: return type of method, or type of newly constructed object

     // location: method_info

     case 0x15:

     // kind: receiver type of method or constructor

     // location: method_info

     {

       // struct:

       // empty_target {

       // }

       //

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("empty_target"));

     } break;

     case 0x16:

     // kind: type in formal parameter declaration of method, constructor, or lambda expression

     // location: method_info

     {

       // struct:

       // formal_parameter_target {

       //   u1 formal_parameter_index;

       // }

       //

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

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

         return false;

       }

       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);

       byte_i_ref += 1;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("formal_parameter_target: formal_parameter_index=%d",

          formal_parameter_index));

     } break;

     case 0x17:

     // kind: type in throws clause of method or constructor

     // location: method_info

     {

       // struct:

       // throws_target {

       //   u2 throws_type_index

       // }

       //

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

         RC_TRACE_WITH_THREAD(0x02000000, THREAD,

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

         return false;

       }

       u2 throws_type_index = Bytes::get_Java_u2((address)

                                type_annotations_typeArray->adr_at(byte_i_ref));

       byte_i_ref += 2;

       RC_TRACE_WITH_THREAD(0x02000000, THREAD,

         ("throws_target: throws_type_index=%d", throws_type_index));

     } break;

     case 0x40:

     // kind: type in local variable declaration

     // location: Code