1 /*
   2  * Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/verifier.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "compiler/compileBroker.hpp"
  31 #include "interpreter/oopMapCache.hpp"
  32 #include "interpreter/rewriter.hpp"
  33 #include "memory/gcLocker.hpp"
  34 #include "memory/metadataFactory.hpp"
  35 #include "memory/metaspaceShared.hpp"
  36 #include "memory/universe.inline.hpp"
  37 #include "oops/fieldStreams.hpp"
  38 #include "oops/klassVtable.hpp"
  39 #include "prims/jvmtiImpl.hpp"
  40 #include "prims/jvmtiRedefineClasses.hpp"
  41 #include "prims/methodComparator.hpp"
  42 #include "runtime/deoptimization.hpp"
  43 #include "runtime/relocator.hpp"
  44 #include "utilities/bitMap.inline.hpp"
  45 
  46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  47 
  48 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
  49 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
  50 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
  51 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
  52 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
  53 Method**  VM_RedefineClasses::_added_methods        = NULL;
  54 int         VM_RedefineClasses::_matching_methods_length = 0;
  55 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  56 int         VM_RedefineClasses::_added_methods_length    = 0;
  57 Klass*      VM_RedefineClasses::_the_class_oop = NULL;
  58 
  59 
  60 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  61                                        const jvmtiClassDefinition *class_defs,
  62                                        JvmtiClassLoadKind class_load_kind) {
  63   _class_count = class_count;
  64   _class_defs = class_defs;
  65   _class_load_kind = class_load_kind;
  66   _res = JVMTI_ERROR_NONE;
  67 }
  68 
  69 bool VM_RedefineClasses::doit_prologue() {
  70   if (_class_count == 0) {
  71     _res = JVMTI_ERROR_NONE;
  72     return false;
  73   }
  74   if (_class_defs == NULL) {
  75     _res = JVMTI_ERROR_NULL_POINTER;
  76     return false;
  77   }
  78   for (int i = 0; i < _class_count; i++) {
  79     if (_class_defs[i].klass == NULL) {
  80       _res = JVMTI_ERROR_INVALID_CLASS;
  81       return false;
  82     }
  83     if (_class_defs[i].class_byte_count == 0) {
  84       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
  85       return false;
  86     }
  87     if (_class_defs[i].class_bytes == NULL) {
  88       _res = JVMTI_ERROR_NULL_POINTER;
  89       return false;
  90     }
  91   }
  92 
  93   // Start timer after all the sanity checks; not quite accurate, but
  94   // better than adding a bunch of stop() calls.
  95   RC_TIMER_START(_timer_vm_op_prologue);
  96 
  97   // We first load new class versions in the prologue, because somewhere down the
  98   // call chain it is required that the current thread is a Java thread.
  99   _res = load_new_class_versions(Thread::current());
 100   if (_res != JVMTI_ERROR_NONE) {
 101     // free any successfully created classes, since none are redefined
 102     for (int i = 0; i < _class_count; i++) {
 103       if (_scratch_classes[i] != NULL) {
 104         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 105         // Free the memory for this class at class unloading time.  Not before
 106         // because CMS might think this is still live.
 107         cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
 108       }
 109     }
 110     // Free os::malloc allocated memory in load_new_class_version.
 111     os::free(_scratch_classes);
 112     RC_TIMER_STOP(_timer_vm_op_prologue);
 113     return false;
 114   }
 115 
 116   RC_TIMER_STOP(_timer_vm_op_prologue);
 117   return true;
 118 }
 119 
 120 void VM_RedefineClasses::doit() {
 121   Thread *thread = Thread::current();
 122 
 123   if (UseSharedSpaces) {
 124     // Sharing is enabled so we remap the shared readonly space to
 125     // shared readwrite, private just in case we need to redefine
 126     // a shared class. We do the remap during the doit() phase of
 127     // the safepoint to be safer.
 128     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
 129       RC_TRACE_WITH_THREAD(0x00000001, thread,
 130         ("failed to remap shared readonly space to readwrite, private"));
 131       _res = JVMTI_ERROR_INTERNAL;
 132       return;
 133     }
 134   }
 135 
 136   // Mark methods seen on stack and everywhere else so old methods are not
 137   // cleaned up if they're on the stack.
 138   MetadataOnStackMark md_on_stack(true);
 139   HandleMark hm(thread);   // make sure any handles created are deleted
 140                            // before the stack walk again.
 141 
 142   for (int i = 0; i < _class_count; i++) {
 143     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 144     ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 145     // Free the memory for this class at class unloading time.  Not before
 146     // because CMS might think this is still live.
 147     cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
 148     _scratch_classes[i] = NULL;
 149   }
 150 
 151   // Disable any dependent concurrent compilations
 152   SystemDictionary::notice_modification();
 153 
 154   // Set flag indicating that some invariants are no longer true.
 155   // See jvmtiExport.hpp for detailed explanation.
 156   JvmtiExport::set_has_redefined_a_class();
 157 
 158 // check_class() is optionally called for product bits, but is
 159 // always called for non-product bits.
 160 #ifdef PRODUCT
 161   if (RC_TRACE_ENABLED(0x00004000)) {
 162 #endif
 163     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
 164     CheckClass check_class(thread);
 165     ClassLoaderDataGraph::classes_do(&check_class);
 166 #ifdef PRODUCT
 167   }
 168 #endif
 169 }
 170 
 171 void VM_RedefineClasses::doit_epilogue() {
 172   // Free os::malloc allocated memory.
 173   os::free(_scratch_classes);
 174 
 175   if (RC_TRACE_ENABLED(0x00000004)) {
 176     // Used to have separate timers for "doit" and "all", but the timer
 177     // overhead skewed the measurements.
 178     jlong doit_time = _timer_rsc_phase1.milliseconds() +
 179                       _timer_rsc_phase2.milliseconds();
 180     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 181 
 182     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
 183       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
 184       _timer_vm_op_prologue.milliseconds(), doit_time));
 185     RC_TRACE(0x00000004,
 186       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
 187        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
 188   }
 189 }
 190 
 191 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 192   // classes for primitives cannot be redefined
 193   if (java_lang_Class::is_primitive(klass_mirror)) {
 194     return false;
 195   }
 196   Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
 197   // classes for arrays cannot be redefined
 198   if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
 199     return false;
 200   }
 201   return true;
 202 }
 203 
 204 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 205 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 206 // direct CP entries, there is just the current entry to append. For
 207 // indirect and double-indirect CP entries, there are zero or more
 208 // referenced CP entries along with the current entry to append.
 209 // Indirect and double-indirect CP entries are handled by recursive
 210 // calls to append_entry() as needed. The referenced CP entries are
 211 // always appended to *merge_cp_p before the referee CP entry. These
 212 // referenced CP entries may already exist in *merge_cp_p in which case
 213 // there is nothing extra to append and only the current entry is
 214 // appended.
 215 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
 216        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 217        TRAPS) {
 218 
 219   // append is different depending on entry tag type
 220   switch (scratch_cp->tag_at(scratch_i).value()) {
 221 
 222     // The old verifier is implemented outside the VM. It loads classes,
 223     // but does not resolve constant pool entries directly so we never
 224     // see Class entries here with the old verifier. Similarly the old
 225     // verifier does not like Class entries in the input constant pool.
 226     // The split-verifier is implemented in the VM so it can optionally
 227     // and directly resolve constant pool entries to load classes. The
 228     // split-verifier can accept either Class entries or UnresolvedClass
 229     // entries in the input constant pool. We revert the appended copy
 230     // back to UnresolvedClass so that either verifier will be happy
 231     // with the constant pool entry.
 232     case JVM_CONSTANT_Class:
 233     {
 234       // revert the copy to JVM_CONSTANT_UnresolvedClass
 235       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
 236         scratch_cp->klass_name_at(scratch_i));
 237 
 238       if (scratch_i != *merge_cp_length_p) {
 239         // The new entry in *merge_cp_p is at a different index than
 240         // the new entry in scratch_cp so we need to map the index values.
 241         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 242       }
 243       (*merge_cp_length_p)++;
 244     } break;
 245 
 246     // these are direct CP entries so they can be directly appended,
 247     // but double and long take two constant pool entries
 248     case JVM_CONSTANT_Double:  // fall through
 249     case JVM_CONSTANT_Long:
 250     {
 251       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 252         THREAD);
 253 
 254       if (scratch_i != *merge_cp_length_p) {
 255         // The new entry in *merge_cp_p is at a different index than
 256         // the new entry in scratch_cp so we need to map the index values.
 257         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 258       }
 259       (*merge_cp_length_p) += 2;
 260     } break;
 261 
 262     // these are direct CP entries so they can be directly appended
 263     case JVM_CONSTANT_Float:   // fall through
 264     case JVM_CONSTANT_Integer: // fall through
 265     case JVM_CONSTANT_Utf8:    // fall through
 266 
 267     // This was an indirect CP entry, but it has been changed into
 268     // Symbol*s so this entry can be directly appended.
 269     case JVM_CONSTANT_String:      // fall through
 270 
 271     // These were indirect CP entries, but they have been changed into
 272     // Symbol*s so these entries can be directly appended.
 273     case JVM_CONSTANT_UnresolvedClass:  // fall through
 274     {
 275       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 276         THREAD);
 277 
 278       if (scratch_i != *merge_cp_length_p) {
 279         // The new entry in *merge_cp_p is at a different index than
 280         // the new entry in scratch_cp so we need to map the index values.
 281         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 282       }
 283       (*merge_cp_length_p)++;
 284     } break;
 285 
 286     // this is an indirect CP entry so it needs special handling
 287     case JVM_CONSTANT_NameAndType:
 288     {
 289       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 290       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
 291                                                          merge_cp_length_p, THREAD);
 292 
 293       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 294       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
 295                                                               merge_cp_p, merge_cp_length_p,
 296                                                               THREAD);
 297 
 298       // If the referenced entries already exist in *merge_cp_p, then
 299       // both new_name_ref_i and new_signature_ref_i will both be 0.
 300       // In that case, all we are appending is the current entry.
 301       if (new_name_ref_i != name_ref_i) {
 302         RC_TRACE(0x00080000,
 303           ("NameAndType entry@%d name_ref_index change: %d to %d",
 304           *merge_cp_length_p, name_ref_i, new_name_ref_i));
 305       }
 306       if (new_signature_ref_i != signature_ref_i) {
 307         RC_TRACE(0x00080000,
 308           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 309           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
 310       }
 311 
 312       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 313         new_name_ref_i, new_signature_ref_i);
 314       if (scratch_i != *merge_cp_length_p) {
 315         // The new entry in *merge_cp_p is at a different index than
 316         // the new entry in scratch_cp so we need to map the index values.
 317         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 318       }
 319       (*merge_cp_length_p)++;
 320     } break;
 321 
 322     // this is a double-indirect CP entry so it needs special handling
 323     case JVM_CONSTANT_Fieldref:           // fall through
 324     case JVM_CONSTANT_InterfaceMethodref: // fall through
 325     case JVM_CONSTANT_Methodref:
 326     {
 327       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 328       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
 329                                                           merge_cp_p, merge_cp_length_p, THREAD);
 330 
 331       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 332       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
 333                                                           merge_cp_p, merge_cp_length_p, THREAD);
 334 
 335       const char *entry_name;
 336       switch (scratch_cp->tag_at(scratch_i).value()) {
 337       case JVM_CONSTANT_Fieldref:
 338         entry_name = "Fieldref";
 339         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 340           new_name_and_type_ref_i);
 341         break;
 342       case JVM_CONSTANT_InterfaceMethodref:
 343         entry_name = "IFMethodref";
 344         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 345           new_klass_ref_i, new_name_and_type_ref_i);
 346         break;
 347       case JVM_CONSTANT_Methodref:
 348         entry_name = "Methodref";
 349         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 350           new_name_and_type_ref_i);
 351         break;
 352       default:
 353         guarantee(false, "bad switch");
 354         break;
 355       }
 356 
 357       if (klass_ref_i != new_klass_ref_i) {
 358         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
 359           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
 360       }
 361       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 362         RC_TRACE(0x00080000,
 363           ("%s entry@%d name_and_type_index changed: %d to %d",
 364           entry_name, *merge_cp_length_p, name_and_type_ref_i,
 365           new_name_and_type_ref_i));
 366       }
 367 
 368       if (scratch_i != *merge_cp_length_p) {
 369         // The new entry in *merge_cp_p is at a different index than
 370         // the new entry in scratch_cp so we need to map the index values.
 371         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 372       }
 373       (*merge_cp_length_p)++;
 374     } break;
 375 
 376     // this is an indirect CP entry so it needs special handling
 377     case JVM_CONSTANT_MethodType:
 378     {
 379       int ref_i = scratch_cp->method_type_index_at(scratch_i);
 380       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 381                                                     merge_cp_length_p, THREAD);
 382       if (new_ref_i != ref_i) {
 383         RC_TRACE(0x00080000,
 384                  ("MethodType entry@%d ref_index change: %d to %d",
 385                   *merge_cp_length_p, ref_i, new_ref_i));
 386       }
 387       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
 388       if (scratch_i != *merge_cp_length_p) {
 389         // The new entry in *merge_cp_p is at a different index than
 390         // the new entry in scratch_cp so we need to map the index values.
 391         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 392       }
 393       (*merge_cp_length_p)++;
 394     } break;
 395 
 396     // this is an indirect CP entry so it needs special handling
 397     case JVM_CONSTANT_MethodHandle:
 398     {
 399       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
 400       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
 401       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 402                                                     merge_cp_length_p, THREAD);
 403       if (new_ref_i != ref_i) {
 404         RC_TRACE(0x00080000,
 405                  ("MethodHandle entry@%d ref_index change: %d to %d",
 406                   *merge_cp_length_p, ref_i, new_ref_i));
 407       }
 408       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
 409       if (scratch_i != *merge_cp_length_p) {
 410         // The new entry in *merge_cp_p is at a different index than
 411         // the new entry in scratch_cp so we need to map the index values.
 412         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 413       }
 414       (*merge_cp_length_p)++;
 415     } break;
 416 
 417     // this is an indirect CP entry so it needs special handling
 418     case JVM_CONSTANT_InvokeDynamic:
 419     {
 420       // Index of the bootstrap specifier in the operands array
 421       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
 422       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
 423                                             merge_cp_length_p, THREAD);
 424       // The bootstrap method NameAndType_info index
 425       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
 426       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 427                                                     merge_cp_length_p, THREAD);
 428       if (new_bs_i != old_bs_i) {
 429         RC_TRACE(0x00080000,
 430                  ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
 431                   *merge_cp_length_p, old_bs_i, new_bs_i));
 432       }
 433       if (new_ref_i != old_ref_i) {
 434         RC_TRACE(0x00080000,
 435                  ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
 436                   *merge_cp_length_p, old_ref_i, new_ref_i));
 437       }
 438 
 439       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
 440       if (scratch_i != *merge_cp_length_p) {
 441         // The new entry in *merge_cp_p is at a different index than
 442         // the new entry in scratch_cp so we need to map the index values.
 443         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 444       }
 445       (*merge_cp_length_p)++;
 446     } break;
 447 
 448     // At this stage, Class or UnresolvedClass could be here, but not
 449     // ClassIndex
 450     case JVM_CONSTANT_ClassIndex: // fall through
 451 
 452     // Invalid is used as the tag for the second constant pool entry
 453     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 454     // not be seen by itself.
 455     case JVM_CONSTANT_Invalid: // fall through
 456 
 457     // At this stage, String could be here, but not StringIndex
 458     case JVM_CONSTANT_StringIndex: // fall through
 459 
 460     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 461     // here
 462     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 463 
 464     default:
 465     {
 466       // leave a breadcrumb
 467       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 468       ShouldNotReachHere();
 469     } break;
 470   } // end switch tag value
 471 } // end append_entry()
 472 
 473 
 474 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
 475       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 476 
 477   int new_ref_i = ref_i;
 478   bool match = (ref_i < *merge_cp_length_p) &&
 479                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
 480 
 481   if (!match) {
 482     // forward reference in *merge_cp_p or not a direct match
 483     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
 484     if (found_i != 0) {
 485       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
 486       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
 487       new_ref_i = found_i;
 488       map_index(scratch_cp, ref_i, found_i);
 489     } else {
 490       // no match found so we have to append this entry to *merge_cp_p
 491       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
 492       // The above call to append_entry() can only append one entry
 493       // so the post call query of *merge_cp_length_p is only for
 494       // the sake of consistency.
 495       new_ref_i = *merge_cp_length_p - 1;
 496     }
 497   }
 498 
 499   return new_ref_i;
 500 } // end find_or_append_indirect_entry()
 501 
 502 
 503 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
 504 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
 505 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
 506 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
 507        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 508 
 509   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
 510   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 511                                                 merge_cp_length_p, THREAD);
 512   if (new_ref_i != old_ref_i) {
 513     RC_TRACE(0x00080000,
 514              ("operands entry@%d bootstrap method ref_index change: %d to %d",
 515               _operands_cur_length, old_ref_i, new_ref_i));
 516   }
 517 
 518   Array<u2>* merge_ops = (*merge_cp_p)->operands();
 519   int new_bs_i = _operands_cur_length;
 520   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
 521   // However, the operand_offset_at(0) was set in the extend_operands() call.
 522   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
 523                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
 524   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
 525 
 526   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
 527   merge_ops->at_put(new_base++, new_ref_i);
 528   merge_ops->at_put(new_base++, argc);
 529 
 530   for (int i = 0; i < argc; i++) {
 531     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
 532     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
 533                                                       merge_cp_length_p, THREAD);
 534     merge_ops->at_put(new_base++, new_arg_ref_i);
 535     if (new_arg_ref_i != old_arg_ref_i) {
 536       RC_TRACE(0x00080000,
 537                ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
 538                 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));
 539     }
 540   }
 541   if (old_bs_i != _operands_cur_length) {
 542     // The bootstrap specifier in *merge_cp_p is at a different index than
 543     // that in scratch_cp so we need to map the index values.
 544     map_operand_index(old_bs_i, new_bs_i);
 545   }
 546   _operands_cur_length++;
 547 } // end append_operand()
 548 
 549 
 550 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
 551       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 552 
 553   int new_bs_i = old_bs_i; // bootstrap specifier index
 554   bool match = (old_bs_i < _operands_cur_length) &&
 555                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
 556 
 557   if (!match) {
 558     // forward reference in *merge_cp_p or not a direct match
 559     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
 560                                                     _operands_cur_length, THREAD);
 561     if (found_i != -1) {
 562       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
 563       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
 564       new_bs_i = found_i;
 565       map_operand_index(old_bs_i, found_i);
 566     } else {
 567       // no match found so we have to append this bootstrap specifier to *merge_cp_p
 568       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
 569       new_bs_i = _operands_cur_length - 1;
 570     }
 571   }
 572   return new_bs_i;
 573 } // end find_or_append_operand()
 574 
 575 
 576 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
 577   if (merge_cp->operands() == NULL) {
 578     return;
 579   }
 580   // Shrink the merge_cp operands
 581   merge_cp->shrink_operands(_operands_cur_length, CHECK);
 582 
 583   if (RC_TRACE_ENABLED(0x00040000)) {
 584     // don't want to loop unless we are tracing
 585     int count = 0;
 586     for (int i = 1; i < _operands_index_map_p->length(); i++) {
 587       int value = _operands_index_map_p->at(i);
 588       if (value != -1) {
 589         RC_TRACE_WITH_THREAD(0x00040000, THREAD,
 590           ("operands_index_map[%d]: old=%d new=%d", count, i, value));
 591         count++;
 592       }
 593     }
 594   }
 595   // Clean-up
 596   _operands_index_map_p = NULL;
 597   _operands_cur_length = 0;
 598   _operands_index_map_count = 0;
 599 } // end finalize_operands_merge()
 600 
 601 
 602 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 603              instanceKlassHandle the_class,
 604              instanceKlassHandle scratch_class) {
 605   int i;
 606 
 607   // Check superclasses, or rather their names, since superclasses themselves can be
 608   // requested to replace.
 609   // Check for NULL superclass first since this might be java.lang.Object
 610   if (the_class->super() != scratch_class->super() &&
 611       (the_class->super() == NULL || scratch_class->super() == NULL ||
 612        the_class->super()->name() !=
 613        scratch_class->super()->name())) {
 614     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 615   }
 616 
 617   // Check if the number, names and order of directly implemented interfaces are the same.
 618   // I think in principle we should just check if the sets of names of directly implemented
 619   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 620   // .java file, also changes in .class file) should not matter. However, comparing sets is
 621   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 622   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 623   // rely on it somewhere.
 624   Array<Klass*>* k_interfaces = the_class->local_interfaces();
 625   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
 626   int n_intfs = k_interfaces->length();
 627   if (n_intfs != k_new_interfaces->length()) {
 628     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 629   }
 630   for (i = 0; i < n_intfs; i++) {
 631     if (k_interfaces->at(i)->name() !=
 632         k_new_interfaces->at(i)->name()) {
 633       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 634     }
 635   }
 636 
 637   // Check whether class is in the error init state.
 638   if (the_class->is_in_error_state()) {
 639     // TBD #5057930: special error code is needed in 1.6
 640     return JVMTI_ERROR_INVALID_CLASS;
 641   }
 642 
 643   // Check whether class modifiers are the same.
 644   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 645   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 646   if (old_flags != new_flags) {
 647     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 648   }
 649 
 650   // Check if the number, names, types and order of fields declared in these classes
 651   // are the same.
 652   JavaFieldStream old_fs(the_class);
 653   JavaFieldStream new_fs(scratch_class);
 654   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 655     // access
 656     old_flags = old_fs.access_flags().as_short();
 657     new_flags = new_fs.access_flags().as_short();
 658     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 659       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 660     }
 661     // offset
 662     if (old_fs.offset() != new_fs.offset()) {
 663       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 664     }
 665     // name and signature
 666     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 667     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 668     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 669     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 670     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 671       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 672     }
 673   }
 674 
 675   // If both streams aren't done then we have a differing number of
 676   // fields.
 677   if (!old_fs.done() || !new_fs.done()) {
 678     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 679   }
 680 
 681   // Do a parallel walk through the old and new methods. Detect
 682   // cases where they match (exist in both), have been added in
 683   // the new methods, or have been deleted (exist only in the
 684   // old methods).  The class file parser places methods in order
 685   // by method name, but does not order overloaded methods by
 686   // signature.  In order to determine what fate befell the methods,
 687   // this code places the overloaded new methods that have matching
 688   // old methods in the same order as the old methods and places
 689   // new overloaded methods at the end of overloaded methods of
 690   // that name. The code for this order normalization is adapted
 691   // from the algorithm used in InstanceKlass::find_method().
 692   // Since we are swapping out of order entries as we find them,
 693   // we only have to search forward through the overloaded methods.
 694   // Methods which are added and have the same name as an existing
 695   // method (but different signature) will be put at the end of
 696   // the methods with that name, and the name mismatch code will
 697   // handle them.
 698   Array<Method*>* k_old_methods(the_class->methods());
 699   Array<Method*>* k_new_methods(scratch_class->methods());
 700   int n_old_methods = k_old_methods->length();
 701   int n_new_methods = k_new_methods->length();
 702   Thread* thread = Thread::current();
 703 
 704   int ni = 0;
 705   int oi = 0;
 706   while (true) {
 707     Method* k_old_method;
 708     Method* k_new_method;
 709     enum { matched, added, deleted, undetermined } method_was = undetermined;
 710 
 711     if (oi >= n_old_methods) {
 712       if (ni >= n_new_methods) {
 713         break; // we've looked at everything, done
 714       }
 715       // New method at the end
 716       k_new_method = k_new_methods->at(ni);
 717       method_was = added;
 718     } else if (ni >= n_new_methods) {
 719       // Old method, at the end, is deleted
 720       k_old_method = k_old_methods->at(oi);
 721       method_was = deleted;
 722     } else {
 723       // There are more methods in both the old and new lists
 724       k_old_method = k_old_methods->at(oi);
 725       k_new_method = k_new_methods->at(ni);
 726       if (k_old_method->name() != k_new_method->name()) {
 727         // Methods are sorted by method name, so a mismatch means added
 728         // or deleted
 729         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 730           method_was = added;
 731         } else {
 732           method_was = deleted;
 733         }
 734       } else if (k_old_method->signature() == k_new_method->signature()) {
 735         // Both the name and signature match
 736         method_was = matched;
 737       } else {
 738         // The name matches, but the signature doesn't, which means we have to
 739         // search forward through the new overloaded methods.
 740         int nj;  // outside the loop for post-loop check
 741         for (nj = ni + 1; nj < n_new_methods; nj++) {
 742           Method* m = k_new_methods->at(nj);
 743           if (k_old_method->name() != m->name()) {
 744             // reached another method name so no more overloaded methods
 745             method_was = deleted;
 746             break;
 747           }
 748           if (k_old_method->signature() == m->signature()) {
 749             // found a match so swap the methods
 750             k_new_methods->at_put(ni, m);
 751             k_new_methods->at_put(nj, k_new_method);
 752             k_new_method = m;
 753             method_was = matched;
 754             break;
 755           }
 756         }
 757 
 758         if (nj >= n_new_methods) {
 759           // reached the end without a match; so method was deleted
 760           method_was = deleted;
 761         }
 762       }
 763     }
 764 
 765     switch (method_was) {
 766     case matched:
 767       // methods match, be sure modifiers do too
 768       old_flags = (jushort) k_old_method->access_flags().get_flags();
 769       new_flags = (jushort) k_new_method->access_flags().get_flags();
 770       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 771         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 772       }
 773       {
 774         u2 new_num = k_new_method->method_idnum();
 775         u2 old_num = k_old_method->method_idnum();
 776         if (new_num != old_num) {
 777           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
 778           if (idnum_owner != NULL) {
 779             // There is already a method assigned this idnum -- switch them
 780             // Take current and original idnum from the new_method
 781             idnum_owner->set_method_idnum(new_num);
 782             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 783           }
 784           // Take current and original idnum from the old_method
 785           k_new_method->set_method_idnum(old_num);
 786           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
 787           if (thread->has_pending_exception()) {
 788             return JVMTI_ERROR_OUT_OF_MEMORY;
 789           }
 790         }
 791       }
 792       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
 793                             k_new_method->name_and_sig_as_C_string(), ni,
 794                             k_old_method->name_and_sig_as_C_string(), oi));
 795       // advance to next pair of methods
 796       ++oi;
 797       ++ni;
 798       break;
 799     case added:
 800       // method added, see if it is OK
 801       new_flags = (jushort) k_new_method->access_flags().get_flags();
 802       if ((new_flags & JVM_ACC_PRIVATE) == 0
 803            // hack: private should be treated as final, but alas
 804           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 805          ) {
 806         // new methods must be private
 807         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 808       }
 809       {
 810         u2 num = the_class->next_method_idnum();
 811         if (num == ConstMethod::UNSET_IDNUM) {
 812           // cannot add any more methods
 813           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 814         }
 815         u2 new_num = k_new_method->method_idnum();
 816         Method* idnum_owner = scratch_class->method_with_idnum(num);
 817         if (idnum_owner != NULL) {
 818           // There is already a method assigned this idnum -- switch them
 819           // Take current and original idnum from the new_method
 820           idnum_owner->set_method_idnum(new_num);
 821           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 822         }
 823         k_new_method->set_method_idnum(num);
 824         k_new_method->set_orig_method_idnum(num);
 825         if (thread->has_pending_exception()) {
 826           return JVMTI_ERROR_OUT_OF_MEMORY;
 827         }
 828       }
 829       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
 830                             k_new_method->name_and_sig_as_C_string(), ni));
 831       ++ni; // advance to next new method
 832       break;
 833     case deleted:
 834       // method deleted, see if it is OK
 835       old_flags = (jushort) k_old_method->access_flags().get_flags();
 836       if ((old_flags & JVM_ACC_PRIVATE) == 0
 837            // hack: private should be treated as final, but alas
 838           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 839          ) {
 840         // deleted methods must be private
 841         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 842       }
 843       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
 844                             k_old_method->name_and_sig_as_C_string(), oi));
 845       ++oi; // advance to next old method
 846       break;
 847     default:
 848       ShouldNotReachHere();
 849     }
 850   }
 851 
 852   return JVMTI_ERROR_NONE;
 853 }
 854 
 855 
 856 // Find new constant pool index value for old constant pool index value
 857 // by seaching the index map. Returns zero (0) if there is no mapped
 858 // value for the old constant pool index.
 859 int VM_RedefineClasses::find_new_index(int old_index) {
 860   if (_index_map_count == 0) {
 861     // map is empty so nothing can be found
 862     return 0;
 863   }
 864 
 865   if (old_index < 1 || old_index >= _index_map_p->length()) {
 866     // The old_index is out of range so it is not mapped. This should
 867     // not happen in regular constant pool merging use, but it can
 868     // happen if a corrupt annotation is processed.
 869     return 0;
 870   }
 871 
 872   int value = _index_map_p->at(old_index);
 873   if (value == -1) {
 874     // the old_index is not mapped
 875     return 0;
 876   }
 877 
 878   return value;
 879 } // end find_new_index()
 880 
 881 
 882 // Find new bootstrap specifier index value for old bootstrap specifier index
 883 // value by seaching the index map. Returns unused index (-1) if there is
 884 // no mapped value for the old bootstrap specifier index.
 885 int VM_RedefineClasses::find_new_operand_index(int old_index) {
 886   if (_operands_index_map_count == 0) {
 887     // map is empty so nothing can be found
 888     return -1;
 889   }
 890 
 891   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
 892     // The old_index is out of range so it is not mapped.
 893     // This should not happen in regular constant pool merging use.
 894     return -1;
 895   }
 896 
 897   int value = _operands_index_map_p->at(old_index);
 898   if (value == -1) {
 899     // the old_index is not mapped
 900     return -1;
 901   }
 902 
 903   return value;
 904 } // end find_new_operand_index()
 905 
 906 
 907 // Returns true if the current mismatch is due to a resolved/unresolved
 908 // class pair. Otherwise, returns false.
 909 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
 910        int index1, constantPoolHandle cp2, int index2) {
 911 
 912   jbyte t1 = cp1->tag_at(index1).value();
 913   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 914     return false;  // wrong entry type; not our special case
 915   }
 916 
 917   jbyte t2 = cp2->tag_at(index2).value();
 918   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 919     return false;  // wrong entry type; not our special case
 920   }
 921 
 922   if (t1 == t2) {
 923     return false;  // not a mismatch; not our special case
 924   }
 925 
 926   char *s1 = cp1->klass_name_at(index1)->as_C_string();
 927   char *s2 = cp2->klass_name_at(index2)->as_C_string();
 928   if (strcmp(s1, s2) != 0) {
 929     return false;  // strings don't match; not our special case
 930   }
 931 
 932   return true;  // made it through the gauntlet; this is our special case
 933 } // end is_unresolved_class_mismatch()
 934 
 935 
 936 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
 937 
 938   // For consistency allocate memory using os::malloc wrapper.
 939   _scratch_classes = (Klass**)
 940     os::malloc(sizeof(Klass*) * _class_count, mtClass);
 941   if (_scratch_classes == NULL) {
 942     return JVMTI_ERROR_OUT_OF_MEMORY;
 943   }
 944   // Zero initialize the _scratch_classes array.
 945   for (int i = 0; i < _class_count; i++) {
 946     _scratch_classes[i] = NULL;
 947   }
 948 
 949   ResourceMark rm(THREAD);
 950 
 951   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
 952   // state can only be NULL if the current thread is exiting which
 953   // should not happen since we're trying to do a RedefineClasses
 954   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
 955   for (int i = 0; i < _class_count; i++) {
 956     // Create HandleMark so that any handles created while loading new class
 957     // versions are deleted. Constant pools are deallocated while merging
 958     // constant pools
 959     HandleMark hm(THREAD);
 960 
 961     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 962     // classes for primitives cannot be redefined
 963     if (!is_modifiable_class(mirror)) {
 964       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
 965     }
 966     Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
 967     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
 968     Symbol*  the_class_sym = the_class->name();
 969 
 970     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 971     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
 972       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
 973       the_class->external_name(), _class_load_kind,
 974       os::available_memory() >> 10));
 975 
 976     ClassFileStream st((u1*) _class_defs[i].class_bytes,
 977       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
 978 
 979     // Parse the stream.
 980     Handle the_class_loader(THREAD, the_class->class_loader());
 981     Handle protection_domain(THREAD, the_class->protection_domain());
 982     // Set redefined class handle in JvmtiThreadState class.
 983     // This redefined class is sent to agent event handler for class file
 984     // load hook event.
 985     state->set_class_being_redefined(&the_class, _class_load_kind);
 986 
 987     Klass* k = SystemDictionary::parse_stream(the_class_sym,
 988                                                 the_class_loader,
 989                                                 protection_domain,
 990                                                 &st,
 991                                                 THREAD);
 992     // Clear class_being_redefined just to be sure.
 993     state->clear_class_being_redefined();
 994 
 995     // TODO: if this is retransform, and nothing changed we can skip it
 996 
 997     instanceKlassHandle scratch_class (THREAD, k);
 998 
 999     // Need to clean up allocated InstanceKlass if there's an error so assign
1000     // the result here. Caller deallocates all the scratch classes in case of
1001     // an error.
1002     _scratch_classes[i] = k;
1003 
1004     if (HAS_PENDING_EXCEPTION) {
1005       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1006       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1007       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
1008         ex_name->as_C_string()));
1009       CLEAR_PENDING_EXCEPTION;
1010 
1011       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1012         return JVMTI_ERROR_UNSUPPORTED_VERSION;
1013       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1014         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1015       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1016         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1017       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1018         // The message will be "XXX (wrong name: YYY)"
1019         return JVMTI_ERROR_NAMES_DONT_MATCH;
1020       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1021         return JVMTI_ERROR_OUT_OF_MEMORY;
1022       } else {  // Just in case more exceptions can be thrown..
1023         return JVMTI_ERROR_FAILS_VERIFICATION;
1024       }
1025     }
1026 
1027     // Ensure class is linked before redefine
1028     if (!the_class->is_linked()) {
1029       the_class->link_class(THREAD);
1030       if (HAS_PENDING_EXCEPTION) {
1031         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1032         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1033         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
1034           ex_name->as_C_string()));
1035         CLEAR_PENDING_EXCEPTION;
1036         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1037           return JVMTI_ERROR_OUT_OF_MEMORY;
1038         } else {
1039           return JVMTI_ERROR_INTERNAL;
1040         }
1041       }
1042     }
1043 
1044     // Do the validity checks in compare_and_normalize_class_versions()
1045     // before verifying the byte codes. By doing these checks first, we
1046     // limit the number of functions that require redirection from
1047     // the_class to scratch_class. In particular, we don't have to
1048     // modify JNI GetSuperclass() and thus won't change its performance.
1049     jvmtiError res = compare_and_normalize_class_versions(the_class,
1050                        scratch_class);
1051     if (res != JVMTI_ERROR_NONE) {
1052       return res;
1053     }
1054 
1055     // verify what the caller passed us
1056     {
1057       // The bug 6214132 caused the verification to fail.
1058       // Information about the_class and scratch_class is temporarily
1059       // recorded into jvmtiThreadState. This data is used to redirect
1060       // the_class to scratch_class in the JVM_* functions called by the
1061       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1062       // description.
1063       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1064       Verifier::verify(
1065         scratch_class, Verifier::ThrowException, true, THREAD);
1066     }
1067 
1068     if (HAS_PENDING_EXCEPTION) {
1069       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1070       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1071       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1072         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
1073       CLEAR_PENDING_EXCEPTION;
1074       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1075         return JVMTI_ERROR_OUT_OF_MEMORY;
1076       } else {
1077         // tell the caller the bytecodes are bad
1078         return JVMTI_ERROR_FAILS_VERIFICATION;
1079       }
1080     }
1081 
1082     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1083     if (HAS_PENDING_EXCEPTION) {
1084       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1085       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1086       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1087         ("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()));
1088       CLEAR_PENDING_EXCEPTION;
1089       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1090         return JVMTI_ERROR_OUT_OF_MEMORY;
1091       } else {
1092         return JVMTI_ERROR_INTERNAL;
1093       }
1094     }
1095 
1096     if (VerifyMergedCPBytecodes) {
1097       // verify what we have done during constant pool merging
1098       {
1099         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1100         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1101       }
1102 
1103       if (HAS_PENDING_EXCEPTION) {
1104         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1105         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1106         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1107           ("verify_byte_codes post merge-CP exception: '%s'",
1108           ex_name->as_C_string()));
1109         CLEAR_PENDING_EXCEPTION;
1110         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1111           return JVMTI_ERROR_OUT_OF_MEMORY;
1112         } else {
1113           // tell the caller that constant pool merging screwed up
1114           return JVMTI_ERROR_INTERNAL;
1115         }
1116       }
1117     }
1118 
1119     Rewriter::rewrite(scratch_class, THREAD);
1120     if (!HAS_PENDING_EXCEPTION) {
1121       scratch_class->link_methods(THREAD);
1122     }
1123     if (HAS_PENDING_EXCEPTION) {
1124       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1125       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1126       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1127         ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()));
1128       CLEAR_PENDING_EXCEPTION;
1129       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1130         return JVMTI_ERROR_OUT_OF_MEMORY;
1131       } else {
1132         return JVMTI_ERROR_INTERNAL;
1133       }
1134     }
1135 
1136     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1137     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1138       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1139       the_class->external_name(), os::available_memory() >> 10));
1140   }
1141 
1142   return JVMTI_ERROR_NONE;
1143 }
1144 
1145 
1146 // Map old_index to new_index as needed. scratch_cp is only needed
1147 // for RC_TRACE() calls.
1148 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1149        int old_index, int new_index) {
1150   if (find_new_index(old_index) != 0) {
1151     // old_index is already mapped
1152     return;
1153   }
1154 
1155   if (old_index == new_index) {
1156     // no mapping is needed
1157     return;
1158   }
1159 
1160   _index_map_p->at_put(old_index, new_index);
1161   _index_map_count++;
1162 
1163   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1164     scratch_cp->tag_at(old_index).value(), old_index, new_index));
1165 } // end map_index()
1166 
1167 
1168 // Map old_index to new_index as needed.
1169 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1170   if (find_new_operand_index(old_index) != -1) {
1171     // old_index is already mapped
1172     return;
1173   }
1174 
1175   if (old_index == new_index) {
1176     // no mapping is needed
1177     return;
1178   }
1179 
1180   _operands_index_map_p->at_put(old_index, new_index);
1181   _operands_index_map_count++;
1182 
1183   RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
1184 } // end map_index()
1185 
1186 
1187 // Merge old_cp and scratch_cp and return the results of the merge via
1188 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1189 // merge_cp_length_p. The entries in old_cp occupy the same locations
1190 // in *merge_cp_p. Also creates a map of indices from entries in
1191 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1192 // entries are only created for entries in scratch_cp that occupy a
1193 // different location in *merged_cp_p.
1194 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1195        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1196        int *merge_cp_length_p, TRAPS) {
1197 
1198   if (merge_cp_p == NULL) {
1199     assert(false, "caller must provide scratch constantPool");
1200     return false; // robustness
1201   }
1202   if (merge_cp_length_p == NULL) {
1203     assert(false, "caller must provide scratch CP length");
1204     return false; // robustness
1205   }
1206   // Worst case we need old_cp->length() + scratch_cp()->length(),
1207   // but the caller might be smart so make sure we have at least
1208   // the minimum.
1209   if ((*merge_cp_p)->length() < old_cp->length()) {
1210     assert(false, "merge area too small");
1211     return false; // robustness
1212   }
1213 
1214   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1215     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1216     scratch_cp->length()));
1217 
1218   {
1219     // Pass 0:
1220     // The old_cp is copied to *merge_cp_p; this means that any code
1221     // using old_cp does not have to change. This work looks like a
1222     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1223     // handle one special case:
1224     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1225     // This will make verification happy.
1226 
1227     int old_i;  // index into old_cp
1228 
1229     // index zero (0) is not used in constantPools
1230     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1231       // leave debugging crumb
1232       jbyte old_tag = old_cp->tag_at(old_i).value();
1233       switch (old_tag) {
1234       case JVM_CONSTANT_Class:
1235       case JVM_CONSTANT_UnresolvedClass:
1236         // revert the copy to JVM_CONSTANT_UnresolvedClass
1237         // May be resolving while calling this so do the same for
1238         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1239         (*merge_cp_p)->unresolved_klass_at_put(old_i,
1240           old_cp->klass_name_at(old_i));
1241         break;
1242 
1243       case JVM_CONSTANT_Double:
1244       case JVM_CONSTANT_Long:
1245         // just copy the entry to *merge_cp_p, but double and long take
1246         // two constant pool entries
1247         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1248         old_i++;
1249         break;
1250 
1251       default:
1252         // just copy the entry to *merge_cp_p
1253         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1254         break;
1255       }
1256     } // end for each old_cp entry
1257 
1258     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1259     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1260 
1261     // We don't need to sanity check that *merge_cp_length_p is within
1262     // *merge_cp_p bounds since we have the minimum on-entry check above.
1263     (*merge_cp_length_p) = old_i;
1264   }
1265 
1266   // merge_cp_len should be the same as old_cp->length() at this point
1267   // so this trace message is really a "warm-and-breathing" message.
1268   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1269     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1270 
1271   int scratch_i;  // index into scratch_cp
1272   {
1273     // Pass 1a:
1274     // Compare scratch_cp entries to the old_cp entries that we have
1275     // already copied to *merge_cp_p. In this pass, we are eliminating
1276     // exact duplicates (matching entry at same index) so we only
1277     // compare entries in the common indice range.
1278     int increment = 1;
1279     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1280     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1281       switch (scratch_cp->tag_at(scratch_i).value()) {
1282       case JVM_CONSTANT_Double:
1283       case JVM_CONSTANT_Long:
1284         // double and long take two constant pool entries
1285         increment = 2;
1286         break;
1287 
1288       default:
1289         increment = 1;
1290         break;
1291       }
1292 
1293       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1294         scratch_i, CHECK_0);
1295       if (match) {
1296         // found a match at the same index so nothing more to do
1297         continue;
1298       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1299                                               *merge_cp_p, scratch_i)) {
1300         // The mismatch in compare_entry_to() above is because of a
1301         // resolved versus unresolved class entry at the same index
1302         // with the same string value. Since Pass 0 reverted any
1303         // class entries to unresolved class entries in *merge_cp_p,
1304         // we go with the unresolved class entry.
1305         continue;
1306       }
1307 
1308       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1309         CHECK_0);
1310       if (found_i != 0) {
1311         guarantee(found_i != scratch_i,
1312           "compare_entry_to() and find_matching_entry() do not agree");
1313 
1314         // Found a matching entry somewhere else in *merge_cp_p so
1315         // just need a mapping entry.
1316         map_index(scratch_cp, scratch_i, found_i);
1317         continue;
1318       }
1319 
1320       // The find_matching_entry() call above could fail to find a match
1321       // due to a resolved versus unresolved class or string entry situation
1322       // like we solved above with the is_unresolved_*_mismatch() calls.
1323       // However, we would have to call is_unresolved_*_mismatch() over
1324       // all of *merge_cp_p (potentially) and that doesn't seem to be
1325       // worth the time.
1326 
1327       // No match found so we have to append this entry and any unique
1328       // referenced entries to *merge_cp_p.
1329       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1330         CHECK_0);
1331     }
1332   }
1333 
1334   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1335     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1336     *merge_cp_length_p, scratch_i, _index_map_count));
1337 
1338   if (scratch_i < scratch_cp->length()) {
1339     // Pass 1b:
1340     // old_cp is smaller than scratch_cp so there are entries in
1341     // scratch_cp that we have not yet processed. We take care of
1342     // those now.
1343     int increment = 1;
1344     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1345       switch (scratch_cp->tag_at(scratch_i).value()) {
1346       case JVM_CONSTANT_Double:
1347       case JVM_CONSTANT_Long:
1348         // double and long take two constant pool entries
1349         increment = 2;
1350         break;
1351 
1352       default:
1353         increment = 1;
1354         break;
1355       }
1356 
1357       int found_i =
1358         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1359       if (found_i != 0) {
1360         // Found a matching entry somewhere else in *merge_cp_p so
1361         // just need a mapping entry.
1362         map_index(scratch_cp, scratch_i, found_i);
1363         continue;
1364       }
1365 
1366       // No match found so we have to append this entry and any unique
1367       // referenced entries to *merge_cp_p.
1368       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1369         CHECK_0);
1370     }
1371 
1372     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1373       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1374       *merge_cp_length_p, scratch_i, _index_map_count));
1375   }
1376   finalize_operands_merge(*merge_cp_p, THREAD);
1377 
1378   return true;
1379 } // end merge_constant_pools()
1380 
1381 
1382 // Scoped object to clean up the constant pool(s) created for merging
1383 class MergeCPCleaner {
1384   ClassLoaderData*   _loader_data;
1385   ConstantPool*      _cp;
1386   ConstantPool*      _scratch_cp;
1387  public:
1388   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1389                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1390   ~MergeCPCleaner() {
1391     _loader_data->add_to_deallocate_list(_cp);
1392     if (_scratch_cp != NULL) {
1393       _loader_data->add_to_deallocate_list(_scratch_cp);
1394     }
1395   }
1396   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1397 };
1398 
1399 // Merge constant pools between the_class and scratch_class and
1400 // potentially rewrite bytecodes in scratch_class to use the merged
1401 // constant pool.
1402 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1403              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1404              TRAPS) {
1405   // worst case merged constant pool length is old and new combined
1406   int merge_cp_length = the_class->constants()->length()
1407         + scratch_class->constants()->length();
1408 
1409   // Constant pools are not easily reused so we allocate a new one
1410   // each time.
1411   // merge_cp is created unsafe for concurrent GC processing.  It
1412   // should be marked safe before discarding it. Even though
1413   // garbage,  if it crosses a card boundary, it may be scanned
1414   // in order to find the start of the first complete object on the card.
1415   ClassLoaderData* loader_data = the_class->class_loader_data();
1416   ConstantPool* merge_cp_oop =
1417     ConstantPool::allocate(loader_data,
1418                            merge_cp_length,
1419                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1420   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1421 
1422   HandleMark hm(THREAD);  // make sure handles are cleared before
1423                           // MergeCPCleaner clears out merge_cp_oop
1424   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1425 
1426   // Get constants() from the old class because it could have been rewritten
1427   // while we were at a safepoint allocating a new constant pool.
1428   constantPoolHandle old_cp(THREAD, the_class->constants());
1429   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1430 
1431   // If the length changed, the class was redefined out from under us. Return
1432   // an error.
1433   if (merge_cp_length != the_class->constants()->length()
1434          + scratch_class->constants()->length()) {
1435     return JVMTI_ERROR_INTERNAL;
1436   }
1437 
1438   // Update the version number of the constant pool
1439   merge_cp->increment_and_save_version(old_cp->version());
1440 
1441   ResourceMark rm(THREAD);
1442   _index_map_count = 0;
1443   _index_map_p = new intArray(scratch_cp->length(), -1);
1444 
1445   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1446   _operands_index_map_count = 0;
1447   _operands_index_map_p = new intArray(
1448     ConstantPool::operand_array_length(scratch_cp->operands()), -1);
1449 
1450   // reference to the cp holder is needed for copy_operands()
1451   merge_cp->set_pool_holder(scratch_class());
1452   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1453                   &merge_cp_length, THREAD);
1454   merge_cp->set_pool_holder(NULL);
1455 
1456   if (!result) {
1457     // The merge can fail due to memory allocation failure or due
1458     // to robustness checks.
1459     return JVMTI_ERROR_INTERNAL;
1460   }
1461 
1462   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1463     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1464 
1465   if (_index_map_count == 0) {
1466     // there is nothing to map between the new and merged constant pools
1467 
1468     if (old_cp->length() == scratch_cp->length()) {
1469       // The old and new constant pools are the same length and the
1470       // index map is empty. This means that the three constant pools
1471       // are equivalent (but not the same). Unfortunately, the new
1472       // constant pool has not gone through link resolution nor have
1473       // the new class bytecodes gone through constant pool cache
1474       // rewriting so we can't use the old constant pool with the new
1475       // class.
1476 
1477       // toss the merged constant pool at return
1478     } else if (old_cp->length() < scratch_cp->length()) {
1479       // The old constant pool has fewer entries than the new constant
1480       // pool and the index map is empty. This means the new constant
1481       // pool is a superset of the old constant pool. However, the old
1482       // class bytecodes have already gone through constant pool cache
1483       // rewriting so we can't use the new constant pool with the old
1484       // class.
1485 
1486       // toss the merged constant pool at return
1487     } else {
1488       // The old constant pool has more entries than the new constant
1489       // pool and the index map is empty. This means that both the old
1490       // and merged constant pools are supersets of the new constant
1491       // pool.
1492 
1493       // Replace the new constant pool with a shrunken copy of the
1494       // merged constant pool
1495       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1496                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1497       // The new constant pool replaces scratch_cp so have cleaner clean it up.
1498       // It can't be cleaned up while there are handles to it.
1499       cp_cleaner.add_scratch_cp(scratch_cp());
1500     }
1501   } else {
1502     if (RC_TRACE_ENABLED(0x00040000)) {
1503       // don't want to loop unless we are tracing
1504       int count = 0;
1505       for (int i = 1; i < _index_map_p->length(); i++) {
1506         int value = _index_map_p->at(i);
1507 
1508         if (value != -1) {
1509           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1510             ("index_map[%d]: old=%d new=%d", count, i, value));
1511           count++;
1512         }
1513       }
1514     }
1515 
1516     // We have entries mapped between the new and merged constant pools
1517     // so we have to rewrite some constant pool references.
1518     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1519       return JVMTI_ERROR_INTERNAL;
1520     }
1521 
1522     // Replace the new constant pool with a shrunken copy of the
1523     // merged constant pool so now the rewritten bytecodes have
1524     // valid references; the previous new constant pool will get
1525     // GCed.
1526     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1527                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1528     // The new constant pool replaces scratch_cp so have cleaner clean it up.
1529     // It can't be cleaned up while there are handles to it.
1530     cp_cleaner.add_scratch_cp(scratch_cp());
1531   }
1532 
1533   return JVMTI_ERROR_NONE;
1534 } // end merge_cp_and_rewrite()
1535 
1536 
1537 // Rewrite constant pool references in klass scratch_class.
1538 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1539        TRAPS) {
1540 
1541   // rewrite constant pool references in the methods:
1542   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1543     // propagate failure back to caller
1544     return false;
1545   }
1546 
1547   // rewrite constant pool references in the class_annotations:
1548   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1549     // propagate failure back to caller
1550     return false;
1551   }
1552 
1553   // rewrite constant pool references in the fields_annotations:
1554   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1555     // propagate failure back to caller
1556     return false;
1557   }
1558 
1559   // rewrite constant pool references in the methods_annotations:
1560   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1561     // propagate failure back to caller
1562     return false;
1563   }
1564 
1565   // rewrite constant pool references in the methods_parameter_annotations:
1566   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1567          THREAD)) {
1568     // propagate failure back to caller
1569     return false;
1570   }
1571 
1572   // rewrite constant pool references in the methods_default_annotations:
1573   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1574          THREAD)) {
1575     // propagate failure back to caller
1576     return false;
1577   }
1578 
1579   // rewrite constant pool references in the class_type_annotations:
1580   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1581     // propagate failure back to caller
1582     return false;
1583   }
1584 
1585   // rewrite constant pool references in the fields_type_annotations:
1586   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1587     // propagate failure back to caller
1588     return false;
1589   }
1590 
1591   // rewrite constant pool references in the methods_type_annotations:
1592   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1593     // propagate failure back to caller
1594     return false;
1595   }
1596 
1597   // There can be type annotations in the Code part of a method_info attribute.
1598   // These annotations are not accessible, even by reflection.
1599   // Currently they are not even parsed by the ClassFileParser.
1600   // If runtime access is added they will also need to be rewritten.
1601 
1602   // rewrite source file name index:
1603   u2 source_file_name_idx = scratch_class->source_file_name_index();
1604   if (source_file_name_idx != 0) {
1605     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1606     if (new_source_file_name_idx != 0) {
1607       scratch_class->set_source_file_name_index(new_source_file_name_idx);
1608     }
1609   }
1610 
1611   // rewrite class generic signature index:
1612   u2 generic_signature_index = scratch_class->generic_signature_index();
1613   if (generic_signature_index != 0) {
1614     u2 new_generic_signature_index = find_new_index(generic_signature_index);
1615     if (new_generic_signature_index != 0) {
1616       scratch_class->set_generic_signature_index(new_generic_signature_index);
1617     }
1618   }
1619 
1620   return true;
1621 } // end rewrite_cp_refs()
1622 
1623 // Rewrite constant pool references in the methods.
1624 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1625        instanceKlassHandle scratch_class, TRAPS) {
1626 
1627   Array<Method*>* methods = scratch_class->methods();
1628 
1629   if (methods == NULL || methods->length() == 0) {
1630     // no methods so nothing to do
1631     return true;
1632   }
1633 
1634   // rewrite constant pool references in the methods:
1635   for (int i = methods->length() - 1; i >= 0; i--) {
1636     methodHandle method(THREAD, methods->at(i));
1637     methodHandle new_method;
1638     rewrite_cp_refs_in_method(method, &new_method, THREAD);
1639     if (!new_method.is_null()) {
1640       // the method has been replaced so save the new method version
1641       // even in the case of an exception.  original method is on the
1642       // deallocation list.
1643       methods->at_put(i, new_method());
1644     }
1645     if (HAS_PENDING_EXCEPTION) {
1646       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1647       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1648       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1649         ("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()));
1650       // Need to clear pending exception here as the super caller sets
1651       // the JVMTI_ERROR_INTERNAL if the returned value is false.
1652       CLEAR_PENDING_EXCEPTION;
1653       return false;
1654     }
1655   }
1656 
1657   return true;
1658 }
1659 
1660 
1661 // Rewrite constant pool references in the specific method. This code
1662 // was adapted from Rewriter::rewrite_method().
1663 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1664        methodHandle *new_method_p, TRAPS) {
1665 
1666   *new_method_p = methodHandle();  // default is no new method
1667 
1668   // We cache a pointer to the bytecodes here in code_base. If GC
1669   // moves the Method*, then the bytecodes will also move which
1670   // will likely cause a crash. We create a No_Safepoint_Verifier
1671   // object to detect whether we pass a possible safepoint in this
1672   // code block.
1673   No_Safepoint_Verifier nsv;
1674 
1675   // Bytecodes and their length
1676   address code_base = method->code_base();
1677   int code_length = method->code_size();
1678 
1679   int bc_length;
1680   for (int bci = 0; bci < code_length; bci += bc_length) {
1681     address bcp = code_base + bci;
1682     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1683 
1684     bc_length = Bytecodes::length_for(c);
1685     if (bc_length == 0) {
1686       // More complicated bytecodes report a length of zero so
1687       // we have to try again a slightly different way.
1688       bc_length = Bytecodes::length_at(method(), bcp);
1689     }
1690 
1691     assert(bc_length != 0, "impossible bytecode length");
1692 
1693     switch (c) {
1694       case Bytecodes::_ldc:
1695       {
1696         int cp_index = *(bcp + 1);
1697         int new_index = find_new_index(cp_index);
1698 
1699         if (StressLdcRewrite && new_index == 0) {
1700           // If we are stressing ldc -> ldc_w rewriting, then we
1701           // always need a new_index value.
1702           new_index = cp_index;
1703         }
1704         if (new_index != 0) {
1705           // the original index is mapped so we have more work to do
1706           if (!StressLdcRewrite && new_index <= max_jubyte) {
1707             // The new value can still use ldc instead of ldc_w
1708             // unless we are trying to stress ldc -> ldc_w rewriting
1709             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1710               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1711               bcp, cp_index, new_index));
1712             *(bcp + 1) = new_index;
1713           } else {
1714             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1715               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1716               Bytecodes::name(c), bcp, cp_index, new_index));
1717             // the new value needs ldc_w instead of ldc
1718             u_char inst_buffer[4]; // max instruction size is 4 bytes
1719             bcp = (address)inst_buffer;
1720             // construct new instruction sequence
1721             *bcp = Bytecodes::_ldc_w;
1722             bcp++;
1723             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1724             // See comment below for difference between put_Java_u2()
1725             // and put_native_u2().
1726             Bytes::put_Java_u2(bcp, new_index);
1727 
1728             Relocator rc(method, NULL /* no RelocatorListener needed */);
1729             methodHandle m;
1730             {
1731               Pause_No_Safepoint_Verifier pnsv(&nsv);
1732 
1733               // ldc is 2 bytes and ldc_w is 3 bytes
1734               m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1735             }
1736 
1737             // return the new method so that the caller can update
1738             // the containing class
1739             *new_method_p = method = m;
1740             // switch our bytecode processing loop from the old method
1741             // to the new method
1742             code_base = method->code_base();
1743             code_length = method->code_size();
1744             bcp = code_base + bci;
1745             c = (Bytecodes::Code)(*bcp);
1746             bc_length = Bytecodes::length_for(c);
1747             assert(bc_length != 0, "sanity check");
1748           } // end we need ldc_w instead of ldc
1749         } // end if there is a mapped index
1750       } break;
1751 
1752       // these bytecodes have a two-byte constant pool index
1753       case Bytecodes::_anewarray      : // fall through
1754       case Bytecodes::_checkcast      : // fall through
1755       case Bytecodes::_getfield       : // fall through
1756       case Bytecodes::_getstatic      : // fall through
1757       case Bytecodes::_instanceof     : // fall through
1758       case Bytecodes::_invokedynamic  : // fall through
1759       case Bytecodes::_invokeinterface: // fall through
1760       case Bytecodes::_invokespecial  : // fall through
1761       case Bytecodes::_invokestatic   : // fall through
1762       case Bytecodes::_invokevirtual  : // fall through
1763       case Bytecodes::_ldc_w          : // fall through
1764       case Bytecodes::_ldc2_w         : // fall through
1765       case Bytecodes::_multianewarray : // fall through
1766       case Bytecodes::_new            : // fall through
1767       case Bytecodes::_putfield       : // fall through
1768       case Bytecodes::_putstatic      :
1769       {
1770         address p = bcp + 1;
1771         int cp_index = Bytes::get_Java_u2(p);
1772         int new_index = find_new_index(cp_index);
1773         if (new_index != 0) {
1774           // the original index is mapped so update w/ new value
1775           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1776             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1777             bcp, cp_index, new_index));
1778           // Rewriter::rewrite_method() uses put_native_u2() in this
1779           // situation because it is reusing the constant pool index
1780           // location for a native index into the ConstantPoolCache.
1781           // Since we are updating the constant pool index prior to
1782           // verification and ConstantPoolCache initialization, we
1783           // need to keep the new index in Java byte order.
1784           Bytes::put_Java_u2(p, new_index);
1785         }
1786       } break;
1787     }
1788   } // end for each bytecode
1789 
1790   // We also need to rewrite the parameter name indexes, if there is
1791   // method parameter data present
1792   if(method->has_method_parameters()) {
1793     const int len = method->method_parameters_length();
1794     MethodParametersElement* elem = method->method_parameters_start();
1795 
1796     for (int i = 0; i < len; i++) {
1797       const u2 cp_index = elem[i].name_cp_index;
1798       const u2 new_cp_index = find_new_index(cp_index);
1799       if (new_cp_index != 0) {
1800         elem[i].name_cp_index = new_cp_index;
1801       }
1802     }
1803   }
1804 } // end rewrite_cp_refs_in_method()
1805 
1806 
1807 // Rewrite constant pool references in the class_annotations field.
1808 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1809        instanceKlassHandle scratch_class, TRAPS) {
1810 
1811   AnnotationArray* class_annotations = scratch_class->class_annotations();
1812   if (class_annotations == NULL || class_annotations->length() == 0) {
1813     // no class_annotations so nothing to do
1814     return true;
1815   }
1816 
1817   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1818     ("class_annotations length=%d", class_annotations->length()));
1819 
1820   int byte_i = 0;  // byte index into class_annotations
1821   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1822            THREAD);
1823 }
1824 
1825 
1826 // Rewrite constant pool references in an annotations typeArray. This
1827 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1828 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1829 //
1830 // annotations_typeArray {
1831 //   u2 num_annotations;
1832 //   annotation annotations[num_annotations];
1833 // }
1834 //
1835 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1836        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1837 
1838   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1839     // not enough room for num_annotations field
1840     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1841       ("length() is too small for num_annotations field"));
1842     return false;
1843   }
1844 
1845   u2 num_annotations = Bytes::get_Java_u2((address)
1846                          annotations_typeArray->adr_at(byte_i_ref));
1847   byte_i_ref += 2;
1848 
1849   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1850     ("num_annotations=%d", num_annotations));
1851 
1852   int calc_num_annotations = 0;
1853   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1854     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1855            byte_i_ref, THREAD)) {
1856       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1857         ("bad annotation_struct at %d", calc_num_annotations));
1858       // propagate failure back to caller
1859       return false;
1860     }
1861   }
1862   assert(num_annotations == calc_num_annotations, "sanity check");
1863 
1864   return true;
1865 } // end rewrite_cp_refs_in_annotations_typeArray()
1866 
1867 
1868 // Rewrite constant pool references in the annotation struct portion of
1869 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1870 // the 2nd-edition of the VM spec:
1871 //
1872 // struct annotation {
1873 //   u2 type_index;
1874 //   u2 num_element_value_pairs;
1875 //   {
1876 //     u2 element_name_index;
1877 //     element_value value;
1878 //   } element_value_pairs[num_element_value_pairs];
1879 // }
1880 //
1881 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1882        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1883   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1884     // not enough room for smallest annotation_struct
1885     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1886       ("length() is too small for annotation_struct"));
1887     return false;
1888   }
1889 
1890   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1891                     byte_i_ref, "mapped old type_index=%d", THREAD);
1892 
1893   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1894                                  annotations_typeArray->adr_at(byte_i_ref));
1895   byte_i_ref += 2;
1896 
1897   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1898     ("type_index=%d  num_element_value_pairs=%d", type_index,
1899     num_element_value_pairs));
1900 
1901   int calc_num_element_value_pairs = 0;
1902   for (; calc_num_element_value_pairs < num_element_value_pairs;
1903        calc_num_element_value_pairs++) {
1904     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1905       // not enough room for another element_name_index, let alone
1906       // the rest of another component
1907       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1908         ("length() is too small for element_name_index"));
1909       return false;
1910     }
1911 
1912     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1913                               annotations_typeArray, byte_i_ref,
1914                               "mapped old element_name_index=%d", THREAD);
1915 
1916     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1917       ("element_name_index=%d", element_name_index));
1918 
1919     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1920            byte_i_ref, THREAD)) {
1921       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1922         ("bad element_value at %d", calc_num_element_value_pairs));
1923       // propagate failure back to caller
1924       return false;
1925     }
1926   } // end for each component
1927   assert(num_element_value_pairs == calc_num_element_value_pairs,
1928     "sanity check");
1929 
1930   return true;
1931 } // end rewrite_cp_refs_in_annotation_struct()
1932 
1933 
1934 // Rewrite a constant pool reference at the current position in
1935 // annotations_typeArray if needed. Returns the original constant
1936 // pool reference if a rewrite was not needed or the new constant
1937 // pool reference if a rewrite was needed.
1938 PRAGMA_DIAG_PUSH
1939 PRAGMA_FORMAT_NONLITERAL_IGNORED
1940 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1941      AnnotationArray* annotations_typeArray, int &byte_i_ref,
1942      const char * trace_mesg, TRAPS) {
1943 
1944   address cp_index_addr = (address)
1945     annotations_typeArray->adr_at(byte_i_ref);
1946   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1947   u2 new_cp_index = find_new_index(old_cp_index);
1948   if (new_cp_index != 0) {
1949     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1950     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1951     old_cp_index = new_cp_index;
1952   }
1953   byte_i_ref += 2;
1954   return old_cp_index;
1955 }
1956 PRAGMA_DIAG_POP
1957 
1958 
1959 // Rewrite constant pool references in the element_value portion of an
1960 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1961 // the 2nd-edition of the VM spec:
1962 //
1963 // struct element_value {
1964 //   u1 tag;
1965 //   union {
1966 //     u2 const_value_index;
1967 //     {
1968 //       u2 type_name_index;
1969 //       u2 const_name_index;
1970 //     } enum_const_value;
1971 //     u2 class_info_index;
1972 //     annotation annotation_value;
1973 //     struct {
1974 //       u2 num_values;
1975 //       element_value values[num_values];
1976 //     } array_value;
1977 //   } value;
1978 // }
1979 //
1980 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1981        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1982 
1983   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1984     // not enough room for a tag let alone the rest of an element_value
1985     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1986       ("length() is too small for a tag"));
1987     return false;
1988   }
1989 
1990   u1 tag = annotations_typeArray->at(byte_i_ref);
1991   byte_i_ref++;
1992   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1993 
1994   switch (tag) {
1995     // These BaseType tag values are from Table 4.2 in VM spec:
1996     case 'B':  // byte
1997     case 'C':  // char
1998     case 'D':  // double
1999     case 'F':  // float
2000     case 'I':  // int
2001     case 'J':  // long
2002     case 'S':  // short
2003     case 'Z':  // boolean
2004 
2005     // The remaining tag values are from Table 4.8 in the 2nd-edition of
2006     // the VM spec:
2007     case 's':
2008     {
2009       // For the above tag values (including the BaseType values),
2010       // value.const_value_index is right union field.
2011 
2012       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2013         // not enough room for a const_value_index
2014         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2015           ("length() is too small for a const_value_index"));
2016         return false;
2017       }
2018 
2019       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2020                                annotations_typeArray, byte_i_ref,
2021                                "mapped old const_value_index=%d", THREAD);
2022 
2023       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2024         ("const_value_index=%d", const_value_index));
2025     } break;
2026 
2027     case 'e':
2028     {
2029       // for the above tag value, value.enum_const_value is right union field
2030 
2031       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2032         // not enough room for a enum_const_value
2033         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2034           ("length() is too small for a enum_const_value"));
2035         return false;
2036       }
2037 
2038       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2039                              annotations_typeArray, byte_i_ref,
2040                              "mapped old type_name_index=%d", THREAD);
2041 
2042       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2043                               annotations_typeArray, byte_i_ref,
2044                               "mapped old const_name_index=%d", THREAD);
2045 
2046       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2047         ("type_name_index=%d  const_name_index=%d", type_name_index,
2048         const_name_index));
2049     } break;
2050 
2051     case 'c':
2052     {
2053       // for the above tag value, value.class_info_index is right union field
2054 
2055       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2056         // not enough room for a class_info_index
2057         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2058           ("length() is too small for a class_info_index"));
2059         return false;
2060       }
2061 
2062       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2063                               annotations_typeArray, byte_i_ref,
2064                               "mapped old class_info_index=%d", THREAD);
2065 
2066       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2067         ("class_info_index=%d", class_info_index));
2068     } break;
2069 
2070     case '@':
2071       // For the above tag value, value.attr_value is the right union
2072       // field. This is a nested annotation.
2073       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2074              byte_i_ref, THREAD)) {
2075         // propagate failure back to caller
2076         return false;
2077       }
2078       break;
2079 
2080     case '[':
2081     {
2082       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2083         // not enough room for a num_values field
2084         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2085           ("length() is too small for a num_values field"));
2086         return false;
2087       }
2088 
2089       // For the above tag value, value.array_value is the right union
2090       // field. This is an array of nested element_value.
2091       u2 num_values = Bytes::get_Java_u2((address)
2092                         annotations_typeArray->adr_at(byte_i_ref));
2093       byte_i_ref += 2;
2094       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
2095 
2096       int calc_num_values = 0;
2097       for (; calc_num_values < num_values; calc_num_values++) {
2098         if (!rewrite_cp_refs_in_element_value(
2099                annotations_typeArray, byte_i_ref, THREAD)) {
2100           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2101             ("bad nested element_value at %d", calc_num_values));
2102           // propagate failure back to caller
2103           return false;
2104         }
2105       }
2106       assert(num_values == calc_num_values, "sanity check");
2107     } break;
2108 
2109     default:
2110       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
2111       return false;
2112   } // end decode tag field
2113 
2114   return true;
2115 } // end rewrite_cp_refs_in_element_value()
2116 
2117 
2118 // Rewrite constant pool references in a fields_annotations field.
2119 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2120        instanceKlassHandle scratch_class, TRAPS) {
2121 
2122   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2123 
2124   if (fields_annotations == NULL || fields_annotations->length() == 0) {
2125     // no fields_annotations so nothing to do
2126     return true;
2127   }
2128 
2129   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2130     ("fields_annotations length=%d", fields_annotations->length()));
2131 
2132   for (int i = 0; i < fields_annotations->length(); i++) {
2133     AnnotationArray* field_annotations = fields_annotations->at(i);
2134     if (field_annotations == NULL || field_annotations->length() == 0) {
2135       // this field does not have any annotations so skip it
2136       continue;
2137     }
2138 
2139     int byte_i = 0;  // byte index into field_annotations
2140     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2141            THREAD)) {
2142       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2143         ("bad field_annotations at %d", i));
2144       // propagate failure back to caller
2145       return false;
2146     }
2147   }
2148 
2149   return true;
2150 } // end rewrite_cp_refs_in_fields_annotations()
2151 
2152 
2153 // Rewrite constant pool references in a methods_annotations field.
2154 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2155        instanceKlassHandle scratch_class, TRAPS) {
2156 
2157   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2158     Method* m = scratch_class->methods()->at(i);
2159     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2160 
2161     if (method_annotations == NULL || method_annotations->length() == 0) {
2162       // this method does not have any annotations so skip it
2163       continue;
2164     }
2165 
2166     int byte_i = 0;  // byte index into method_annotations
2167     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2168            THREAD)) {
2169       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2170         ("bad method_annotations at %d", i));
2171       // propagate failure back to caller
2172       return false;
2173     }
2174   }
2175 
2176   return true;
2177 } // end rewrite_cp_refs_in_methods_annotations()
2178 
2179 
2180 // Rewrite constant pool references in a methods_parameter_annotations
2181 // field. This "structure" is adapted from the
2182 // RuntimeVisibleParameterAnnotations_attribute described in section
2183 // 4.8.17 of the 2nd-edition of the VM spec:
2184 //
2185 // methods_parameter_annotations_typeArray {
2186 //   u1 num_parameters;
2187 //   {
2188 //     u2 num_annotations;
2189 //     annotation annotations[num_annotations];
2190 //   } parameter_annotations[num_parameters];
2191 // }
2192 //
2193 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2194        instanceKlassHandle scratch_class, TRAPS) {
2195 
2196   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2197     Method* m = scratch_class->methods()->at(i);
2198     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2199     if (method_parameter_annotations == NULL
2200         || method_parameter_annotations->length() == 0) {
2201       // this method does not have any parameter annotations so skip it
2202       continue;
2203     }
2204 
2205     if (method_parameter_annotations->length() < 1) {
2206       // not enough room for a num_parameters field
2207       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2208         ("length() is too small for a num_parameters field at %d", i));
2209       return false;
2210     }
2211 
2212     int byte_i = 0;  // byte index into method_parameter_annotations
2213 
2214     u1 num_parameters = method_parameter_annotations->at(byte_i);
2215     byte_i++;
2216 
2217     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2218       ("num_parameters=%d", num_parameters));
2219 
2220     int calc_num_parameters = 0;
2221     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2222       if (!rewrite_cp_refs_in_annotations_typeArray(
2223              method_parameter_annotations, byte_i, THREAD)) {
2224         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2225           ("bad method_parameter_annotations at %d", calc_num_parameters));
2226         // propagate failure back to caller
2227         return false;
2228       }
2229     }
2230     assert(num_parameters == calc_num_parameters, "sanity check");
2231   }
2232 
2233   return true;
2234 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2235 
2236 
2237 // Rewrite constant pool references in a methods_default_annotations
2238 // field. This "structure" is adapted from the AnnotationDefault_attribute
2239 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2240 //
2241 // methods_default_annotations_typeArray {
2242 //   element_value default_value;
2243 // }
2244 //
2245 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2246        instanceKlassHandle scratch_class, TRAPS) {
2247 
2248   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2249     Method* m = scratch_class->methods()->at(i);
2250     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2251     if (method_default_annotations == NULL
2252         || method_default_annotations->length() == 0) {
2253       // this method does not have any default annotations so skip it
2254       continue;
2255     }
2256 
2257     int byte_i = 0;  // byte index into method_default_annotations
2258 
2259     if (!rewrite_cp_refs_in_element_value(
2260            method_default_annotations, byte_i, THREAD)) {
2261       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2262         ("bad default element_value at %d", i));
2263       // propagate failure back to caller
2264       return false;
2265     }
2266   }
2267 
2268   return true;
2269 } // end rewrite_cp_refs_in_methods_default_annotations()
2270 
2271 
2272 // Rewrite constant pool references in a class_type_annotations field.
2273 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2274        instanceKlassHandle scratch_class, TRAPS) {
2275 
2276   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2277   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2278     // no class_type_annotations so nothing to do
2279     return true;
2280   }
2281 
2282   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2283     ("class_type_annotations length=%d", class_type_annotations->length()));
2284 
2285   int byte_i = 0;  // byte index into class_type_annotations
2286   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2287       byte_i, "ClassFile", THREAD);
2288 } // end rewrite_cp_refs_in_class_type_annotations()
2289 
2290 
2291 // Rewrite constant pool references in a fields_type_annotations field.
2292 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2293        instanceKlassHandle scratch_class, TRAPS) {
2294 
2295   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2296   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2297     // no fields_type_annotations so nothing to do
2298     return true;
2299   }
2300 
2301   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2302     ("fields_type_annotations length=%d", fields_type_annotations->length()));
2303 
2304   for (int i = 0; i < fields_type_annotations->length(); i++) {
2305     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2306     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2307       // this field does not have any annotations so skip it
2308       continue;
2309     }
2310 
2311     int byte_i = 0;  // byte index into field_type_annotations
2312     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2313            byte_i, "field_info", THREAD)) {
2314       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2315         ("bad field_type_annotations at %d", i));
2316       // propagate failure back to caller
2317       return false;
2318     }
2319   }
2320 
2321   return true;
2322 } // end rewrite_cp_refs_in_fields_type_annotations()
2323 
2324 
2325 // Rewrite constant pool references in a methods_type_annotations field.
2326 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2327        instanceKlassHandle scratch_class, TRAPS) {
2328 
2329   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2330     Method* m = scratch_class->methods()->at(i);
2331     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2332 
2333     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2334       // this method does not have any annotations so skip it
2335       continue;
2336     }
2337 
2338     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2339         ("methods type_annotations length=%d", method_type_annotations->length()));
2340 
2341     int byte_i = 0;  // byte index into method_type_annotations
2342     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2343            byte_i, "method_info", THREAD)) {
2344       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2345         ("bad method_type_annotations at %d", i));
2346       // propagate failure back to caller
2347       return false;
2348     }
2349   }
2350 
2351   return true;
2352 } // end rewrite_cp_refs_in_methods_type_annotations()
2353 
2354 
2355 // Rewrite constant pool references in a type_annotations
2356 // field. This "structure" is adapted from the
2357 // RuntimeVisibleTypeAnnotations_attribute described in
2358 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2359 //
2360 // type_annotations_typeArray {
2361 //   u2              num_annotations;
2362 //   type_annotation annotations[num_annotations];
2363 // }
2364 //
2365 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2366        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2367        const char * location_mesg, TRAPS) {
2368 
2369   if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2370     // not enough room for num_annotations field
2371     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2372       ("length() is too small for num_annotations field"));
2373     return false;
2374   }
2375 
2376   u2 num_annotations = Bytes::get_Java_u2((address)
2377                          type_annotations_typeArray->adr_at(byte_i_ref));
2378   byte_i_ref += 2;
2379 
2380   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2381     ("num_type_annotations=%d", num_annotations));
2382 
2383   int calc_num_annotations = 0;
2384   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2385     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2386            byte_i_ref, location_mesg, THREAD)) {
2387       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2388         ("bad type_annotation_struct at %d", calc_num_annotations));
2389       // propagate failure back to caller
2390       return false;
2391     }
2392   }
2393   assert(num_annotations == calc_num_annotations, "sanity check");
2394 
2395   if (byte_i_ref != type_annotations_typeArray->length()) {
2396     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2397       ("read wrong amount of bytes at end of processing "
2398        "type_annotations_typeArray (%d of %d bytes were read)",
2399        byte_i_ref, type_annotations_typeArray->length()));
2400     return false;
2401   }
2402 
2403   return true;
2404 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2405 
2406 
2407 // Rewrite constant pool references in a type_annotation
2408 // field. This "structure" is adapted from the
2409 // RuntimeVisibleTypeAnnotations_attribute described in
2410 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2411 //
2412 // type_annotation {
2413 //   u1 target_type;
2414 //   union {
2415 //     type_parameter_target;
2416 //     supertype_target;
2417 //     type_parameter_bound_target;
2418 //     empty_target;
2419 //     method_formal_parameter_target;
2420 //     throws_target;
2421 //     localvar_target;
2422 //     catch_target;
2423 //     offset_target;
2424 //     type_argument_target;
2425 //   } target_info;
2426 //   type_path target_path;
2427 //   annotation anno;
2428 // }
2429 //
2430 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2431        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2432        const char * location_mesg, TRAPS) {
2433 
2434   if (!skip_type_annotation_target(type_annotations_typeArray,
2435          byte_i_ref, location_mesg, THREAD)) {
2436     return false;
2437   }
2438 
2439   if (!skip_type_annotation_type_path(type_annotations_typeArray,
2440          byte_i_ref, THREAD)) {
2441     return false;
2442   }
2443 
2444   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2445          byte_i_ref, THREAD)) {
2446     return false;
2447   }
2448 
2449   return true;
2450 } // end rewrite_cp_refs_in_type_annotation_struct()
2451 
2452 
2453 // Read, verify and skip over the target_type and target_info part
2454 // so that rewriting can continue in the later parts of the struct.
2455 //
2456 // u1 target_type;
2457 // union {
2458 //   type_parameter_target;
2459 //   supertype_target;
2460 //   type_parameter_bound_target;
2461 //   empty_target;
2462 //   method_formal_parameter_target;
2463 //   throws_target;
2464 //   localvar_target;
2465 //   catch_target;
2466 //   offset_target;
2467 //   type_argument_target;
2468 // } target_info;
2469 //
2470 bool VM_RedefineClasses::skip_type_annotation_target(
2471        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2472        const char * location_mesg, TRAPS) {
2473 
2474   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2475     // not enough room for a target_type let alone the rest of a type_annotation
2476     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2477       ("length() is too small for a target_type"));
2478     return false;
2479   }
2480 
2481   u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2482   byte_i_ref += 1;
2483   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("target_type=0x%.2x", target_type));
2484   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("location=%s", location_mesg));
2485 
2486   // Skip over target_info
2487   switch (target_type) {
2488     case 0x00:
2489     // kind: type parameter declaration of generic class or interface
2490     // location: ClassFile
2491     case 0x01:
2492     // kind: type parameter declaration of generic method or constructor
2493     // location: method_info
2494 
2495     {
2496       // struct:
2497       // type_parameter_target {
2498       //   u1 type_parameter_index;
2499       // }
2500       //
2501       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2502         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2503           ("length() is too small for a type_parameter_target"));
2504         return false;
2505       }
2506 
2507       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2508       byte_i_ref += 1;
2509 
2510       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2511         ("type_parameter_target: type_parameter_index=%d",
2512          type_parameter_index));
2513     } break;
2514 
2515     case 0x10:
2516     // kind: type in extends clause of class or interface declaration
2517     //       (including the direct superclass of an anonymous class declaration),
2518     //       or in implements clause of interface declaration
2519     // location: ClassFile
2520 
2521     {
2522       // struct:
2523       // supertype_target {
2524       //   u2 supertype_index;
2525       // }
2526       //
2527       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2528         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2529           ("length() is too small for a supertype_target"));
2530         return false;
2531       }
2532 
2533       u2 supertype_index = Bytes::get_Java_u2((address)
2534                              type_annotations_typeArray->adr_at(byte_i_ref));
2535       byte_i_ref += 2;
2536 
2537       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2538         ("supertype_target: supertype_index=%d", supertype_index));
2539     } break;
2540 
2541     case 0x11:
2542     // kind: type in bound of type parameter declaration of generic class or interface
2543     // location: ClassFile
2544     case 0x12:
2545     // kind: type in bound of type parameter declaration of generic method or constructor
2546     // location: method_info
2547 
2548     {
2549       // struct:
2550       // type_parameter_bound_target {
2551       //   u1 type_parameter_index;
2552       //   u1 bound_index;
2553       // }
2554       //
2555       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2556         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2557           ("length() is too small for a type_parameter_bound_target"));
2558         return false;
2559       }
2560 
2561       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2562       byte_i_ref += 1;
2563       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2564       byte_i_ref += 1;
2565 
2566       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2567         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d",
2568          type_parameter_index, bound_index));
2569     } break;
2570 
2571     case 0x13:
2572     // kind: type in field declaration
2573     // location: field_info
2574     case 0x14:
2575     // kind: return type of method, or type of newly constructed object
2576     // location: method_info
2577     case 0x15:
2578     // kind: receiver type of method or constructor
2579     // location: method_info
2580 
2581     {
2582       // struct:
2583       // empty_target {
2584       // }
2585       //
2586       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2587         ("empty_target"));
2588     } break;
2589 
2590     case 0x16:
2591     // kind: type in formal parameter declaration of method, constructor, or lambda expression
2592     // location: method_info
2593 
2594     {
2595       // struct:
2596       // formal_parameter_target {
2597       //   u1 formal_parameter_index;
2598       // }
2599       //
2600       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2601         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2602           ("length() is too small for a formal_parameter_target"));
2603         return false;
2604       }
2605 
2606       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2607       byte_i_ref += 1;
2608 
2609       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2610         ("formal_parameter_target: formal_parameter_index=%d",
2611          formal_parameter_index));
2612     } break;
2613 
2614     case 0x17:
2615     // kind: type in throws clause of method or constructor
2616     // location: method_info
2617 
2618     {
2619       // struct:
2620       // throws_target {
2621       //   u2 throws_type_index
2622       // }
2623       //
2624       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2625         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2626           ("length() is too small for a throws_target"));
2627         return false;
2628       }
2629 
2630       u2 throws_type_index = Bytes::get_Java_u2((address)
2631                                type_annotations_typeArray->adr_at(byte_i_ref));
2632       byte_i_ref += 2;
2633 
2634       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2635         ("throws_target: throws_type_index=%d", throws_type_index));
2636     } break;
2637 
2638     case 0x40:
2639     // kind: type in local variable declaration
2640     // location: Code
2641     case 0x41:
2642     // kind: type in resource variable declaration
2643     // location: Code
2644 
2645     {
2646       // struct:
2647       // localvar_target {
2648       //   u2 table_length;
2649       //   struct {
2650       //     u2 start_pc;
2651       //     u2 length;
2652       //     u2 index;
2653       //   } table[table_length];
2654       // }
2655       //
2656       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2657         // not enough room for a table_length let alone the rest of a localvar_target
2658         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2659           ("length() is too small for a localvar_target table_length"));
2660         return false;
2661       }
2662 
2663       u2 table_length = Bytes::get_Java_u2((address)
2664                           type_annotations_typeArray->adr_at(byte_i_ref));
2665       byte_i_ref += 2;
2666 
2667       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2668         ("localvar_target: table_length=%d", table_length));
2669 
2670       int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2671       int table_size = table_length * table_struct_size;
2672 
2673       if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2674         // not enough room for a table
2675         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2676           ("length() is too small for a table array of length %d", table_length));
2677         return false;
2678       }
2679 
2680       // Skip over table
2681       byte_i_ref += table_size;
2682     } break;
2683 
2684     case 0x42:
2685     // kind: type in exception parameter declaration
2686     // location: Code
2687 
2688     {
2689       // struct:
2690       // catch_target {
2691       //   u2 exception_table_index;
2692       // }
2693       //
2694       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2695         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2696           ("length() is too small for a catch_target"));
2697         return false;
2698       }
2699 
2700       u2 exception_table_index = Bytes::get_Java_u2((address)
2701                                    type_annotations_typeArray->adr_at(byte_i_ref));
2702       byte_i_ref += 2;
2703 
2704       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2705         ("catch_target: exception_table_index=%d", exception_table_index));
2706     } break;
2707 
2708     case 0x43:
2709     // kind: type in instanceof expression
2710     // location: Code
2711     case 0x44:
2712     // kind: type in new expression
2713     // location: Code
2714     case 0x45:
2715     // kind: type in method reference expression using ::new
2716     // location: Code
2717     case 0x46:
2718     // kind: type in method reference expression using ::Identifier
2719     // location: Code
2720 
2721     {
2722       // struct:
2723       // offset_target {
2724       //   u2 offset;
2725       // }
2726       //
2727       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2728         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2729           ("length() is too small for a offset_target"));
2730         return false;
2731       }
2732 
2733       u2 offset = Bytes::get_Java_u2((address)
2734                     type_annotations_typeArray->adr_at(byte_i_ref));
2735       byte_i_ref += 2;
2736 
2737       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2738         ("offset_target: offset=%d", offset));
2739     } break;
2740 
2741     case 0x47:
2742     // kind: type in cast expression
2743     // location: Code
2744     case 0x48:
2745     // kind: type argument for generic constructor in new expression or
2746     //       explicit constructor invocation statement
2747     // location: Code
2748     case 0x49:
2749     // kind: type argument for generic method in method invocation expression
2750     // location: Code
2751     case 0x4A:
2752     // kind: type argument for generic constructor in method reference expression using ::new
2753     // location: Code
2754     case 0x4B:
2755     // kind: type argument for generic method in method reference expression using ::Identifier
2756     // location: Code
2757 
2758     {
2759       // struct:
2760       // type_argument_target {
2761       //   u2 offset;
2762       //   u1 type_argument_index;
2763       // }
2764       //
2765       if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2766         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2767           ("length() is too small for a type_argument_target"));
2768         return false;
2769       }
2770 
2771       u2 offset = Bytes::get_Java_u2((address)
2772                     type_annotations_typeArray->adr_at(byte_i_ref));
2773       byte_i_ref += 2;
2774       u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2775       byte_i_ref += 1;
2776 
2777       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2778         ("type_argument_target: offset=%d, type_argument_index=%d",
2779          offset, type_argument_index));
2780     } break;
2781 
2782     default:
2783       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2784         ("unknown target_type"));
2785 #ifdef ASSERT
2786       ShouldNotReachHere();
2787 #endif
2788       return false;
2789   }
2790 
2791   return true;
2792 } // end skip_type_annotation_target()
2793 
2794 
2795 // Read, verify and skip over the type_path part so that rewriting
2796 // can continue in the later parts of the struct.
2797 //
2798 // type_path {
2799 //   u1 path_length;
2800 //   {
2801 //     u1 type_path_kind;
2802 //     u1 type_argument_index;
2803 //   } path[path_length];
2804 // }
2805 //
2806 bool VM_RedefineClasses::skip_type_annotation_type_path(
2807        AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2808 
2809   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2810     // not enough room for a path_length let alone the rest of the type_path
2811     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2812       ("length() is too small for a type_path"));
2813     return false;
2814   }
2815 
2816   u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2817   byte_i_ref += 1;
2818 
2819   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2820     ("type_path: path_length=%d", path_length));
2821 
2822   int calc_path_length = 0;
2823   for (; calc_path_length < path_length; calc_path_length++) {
2824     if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2825       // not enough room for a path
2826       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2827         ("length() is too small for path entry %d of %d",
2828          calc_path_length, path_length));
2829       return false;
2830     }
2831 
2832     u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2833     byte_i_ref += 1;
2834     u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2835     byte_i_ref += 1;
2836 
2837     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2838       ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2839        calc_path_length, type_path_kind, type_argument_index));
2840 
2841     if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2842       // not enough room for a path
2843       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2844         ("inconsistent type_path values"));
2845       return false;
2846     }
2847   }
2848   assert(path_length == calc_path_length, "sanity check");
2849 
2850   return true;
2851 } // end skip_type_annotation_type_path()
2852 
2853 
2854 // Rewrite constant pool references in the method's stackmap table.
2855 // These "structures" are adapted from the StackMapTable_attribute that
2856 // is described in section 4.8.4 of the 6.0 version of the VM spec
2857 // (dated 2005.10.26):
2858 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2859 //
2860 // stack_map {
2861 //   u2 number_of_entries;
2862 //   stack_map_frame entries[number_of_entries];
2863 // }
2864 //
2865 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2866        methodHandle method, TRAPS) {
2867 
2868   if (!method->has_stackmap_table()) {
2869     return;
2870   }
2871 
2872   AnnotationArray* stackmap_data = method->stackmap_data();
2873   address stackmap_p = (address)stackmap_data->adr_at(0);
2874   address stackmap_end = stackmap_p + stackmap_data->length();
2875 
2876   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2877   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2878   stackmap_p += 2;
2879 
2880   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2881     ("number_of_entries=%u", number_of_entries));
2882 
2883   // walk through each stack_map_frame
2884   u2 calc_number_of_entries = 0;
2885   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2886     // The stack_map_frame structure is a u1 frame_type followed by
2887     // 0 or more bytes of data:
2888     //
2889     // union stack_map_frame {
2890     //   same_frame;
2891     //   same_locals_1_stack_item_frame;
2892     //   same_locals_1_stack_item_frame_extended;
2893     //   chop_frame;
2894     //   same_frame_extended;
2895     //   append_frame;
2896     //   full_frame;
2897     // }
2898 
2899     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2900     // The Linux compiler does not like frame_type to be u1 or u2. It
2901     // issues the following warning for the first if-statement below:
2902     //
2903     // "warning: comparison is always true due to limited range of data type"
2904     //
2905     u4 frame_type = *stackmap_p;
2906     stackmap_p++;
2907 
2908     // same_frame {
2909     //   u1 frame_type = SAME; /* 0-63 */
2910     // }
2911     if (frame_type >= 0 && frame_type <= 63) {
2912       // nothing more to do for same_frame
2913     }
2914 
2915     // same_locals_1_stack_item_frame {
2916     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2917     //   verification_type_info stack[1];
2918     // }
2919     else if (frame_type >= 64 && frame_type <= 127) {
2920       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2921         calc_number_of_entries, frame_type, THREAD);
2922     }
2923 
2924     // reserved for future use
2925     else if (frame_type >= 128 && frame_type <= 246) {
2926       // nothing more to do for reserved frame_types
2927     }
2928 
2929     // same_locals_1_stack_item_frame_extended {
2930     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2931     //   u2 offset_delta;
2932     //   verification_type_info stack[1];
2933     // }
2934     else if (frame_type == 247) {
2935       stackmap_p += 2;
2936       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2937         calc_number_of_entries, frame_type, THREAD);
2938     }
2939 
2940     // chop_frame {
2941     //   u1 frame_type = CHOP; /* 248-250 */
2942     //   u2 offset_delta;
2943     // }
2944     else if (frame_type >= 248 && frame_type <= 250) {
2945       stackmap_p += 2;
2946     }
2947 
2948     // same_frame_extended {
2949     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2950     //   u2 offset_delta;
2951     // }
2952     else if (frame_type == 251) {
2953       stackmap_p += 2;
2954     }
2955 
2956     // append_frame {
2957     //   u1 frame_type = APPEND; /* 252-254 */
2958     //   u2 offset_delta;
2959     //   verification_type_info locals[frame_type - 251];
2960     // }
2961     else if (frame_type >= 252 && frame_type <= 254) {
2962       assert(stackmap_p + 2 <= stackmap_end,
2963         "no room for offset_delta");
2964       stackmap_p += 2;
2965       u1 len = frame_type - 251;
2966       for (u1 i = 0; i < len; i++) {
2967         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2968           calc_number_of_entries, frame_type, THREAD);
2969       }
2970     }
2971 
2972     // full_frame {
2973     //   u1 frame_type = FULL_FRAME; /* 255 */
2974     //   u2 offset_delta;
2975     //   u2 number_of_locals;
2976     //   verification_type_info locals[number_of_locals];
2977     //   u2 number_of_stack_items;
2978     //   verification_type_info stack[number_of_stack_items];
2979     // }
2980     else if (frame_type == 255) {
2981       assert(stackmap_p + 2 + 2 <= stackmap_end,
2982         "no room for smallest full_frame");
2983       stackmap_p += 2;
2984 
2985       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2986       stackmap_p += 2;
2987 
2988       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2989         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2990           calc_number_of_entries, frame_type, THREAD);
2991       }
2992 
2993       // Use the largest size for the number_of_stack_items, but only get
2994       // the right number of bytes.
2995       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2996       stackmap_p += 2;
2997 
2998       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2999         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3000           calc_number_of_entries, frame_type, THREAD);
3001       }
3002     }
3003   } // end while there is a stack_map_frame
3004   assert(number_of_entries == calc_number_of_entries, "sanity check");
3005 } // end rewrite_cp_refs_in_stack_map_table()
3006 
3007 
3008 // Rewrite constant pool references in the verification type info
3009 // portion of the method's stackmap table. These "structures" are
3010 // adapted from the StackMapTable_attribute that is described in
3011 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3012 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3013 //
3014 // The verification_type_info structure is a u1 tag followed by 0 or
3015 // more bytes of data:
3016 //
3017 // union verification_type_info {
3018 //   Top_variable_info;
3019 //   Integer_variable_info;
3020 //   Float_variable_info;
3021 //   Long_variable_info;
3022 //   Double_variable_info;
3023 //   Null_variable_info;
3024 //   UninitializedThis_variable_info;
3025 //   Object_variable_info;
3026 //   Uninitialized_variable_info;
3027 // }
3028 //
3029 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3030        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3031        u1 frame_type, TRAPS) {
3032 
3033   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3034   u1 tag = *stackmap_p_ref;
3035   stackmap_p_ref++;
3036 
3037   switch (tag) {
3038   // Top_variable_info {
3039   //   u1 tag = ITEM_Top; /* 0 */
3040   // }
3041   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3042   case 0:  // fall through
3043 
3044   // Integer_variable_info {
3045   //   u1 tag = ITEM_Integer; /* 1 */
3046   // }
3047   case ITEM_Integer:  // fall through
3048 
3049   // Float_variable_info {
3050   //   u1 tag = ITEM_Float; /* 2 */
3051   // }
3052   case ITEM_Float:  // fall through
3053 
3054   // Double_variable_info {
3055   //   u1 tag = ITEM_Double; /* 3 */
3056   // }
3057   case ITEM_Double:  // fall through
3058 
3059   // Long_variable_info {
3060   //   u1 tag = ITEM_Long; /* 4 */
3061   // }
3062   case ITEM_Long:  // fall through
3063 
3064   // Null_variable_info {
3065   //   u1 tag = ITEM_Null; /* 5 */
3066   // }
3067   case ITEM_Null:  // fall through
3068 
3069   // UninitializedThis_variable_info {
3070   //   u1 tag = ITEM_UninitializedThis; /* 6 */
3071   // }
3072   case ITEM_UninitializedThis:
3073     // nothing more to do for the above tag types
3074     break;
3075 
3076   // Object_variable_info {
3077   //   u1 tag = ITEM_Object; /* 7 */
3078   //   u2 cpool_index;
3079   // }
3080   case ITEM_Object:
3081   {
3082     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3083     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3084     u2 new_cp_index = find_new_index(cpool_index);
3085     if (new_cp_index != 0) {
3086       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3087         ("mapped old cpool_index=%d", cpool_index));
3088       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3089       cpool_index = new_cp_index;
3090     }
3091     stackmap_p_ref += 2;
3092 
3093     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3094       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
3095       frame_type, cpool_index));
3096   } break;
3097 
3098   // Uninitialized_variable_info {
3099   //   u1 tag = ITEM_Uninitialized; /* 8 */
3100   //   u2 offset;
3101   // }
3102   case ITEM_Uninitialized:
3103     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3104     stackmap_p_ref += 2;
3105     break;
3106 
3107   default:
3108     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3109       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
3110     ShouldNotReachHere();
3111     break;
3112   } // end switch (tag)
3113 } // end rewrite_cp_refs_in_verification_type_info()
3114 
3115 
3116 // Change the constant pool associated with klass scratch_class to
3117 // scratch_cp. If shrink is true, then scratch_cp_length elements
3118 // are copied from scratch_cp to a smaller constant pool and the
3119 // smaller constant pool is associated with scratch_class.
3120 void VM_RedefineClasses::set_new_constant_pool(
3121        ClassLoaderData* loader_data,
3122        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
3123        int scratch_cp_length, TRAPS) {
3124   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3125 
3126   // scratch_cp is a merged constant pool and has enough space for a
3127   // worst case merge situation. We want to associate the minimum
3128   // sized constant pool with the klass to save space.
3129   ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3130   constantPoolHandle smaller_cp(THREAD, cp);
3131 
3132   // preserve version() value in the smaller copy
3133   int version = scratch_cp->version();
3134   assert(version != 0, "sanity check");
3135   smaller_cp->set_version(version);
3136 
3137   // attach klass to new constant pool
3138   // reference to the cp holder is needed for copy_operands()
3139   smaller_cp->set_pool_holder(scratch_class());
3140 
3141   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3142   if (HAS_PENDING_EXCEPTION) {
3143     // Exception is handled in the caller
3144     loader_data->add_to_deallocate_list(smaller_cp());
3145     return;
3146   }
3147   scratch_cp = smaller_cp;
3148 
3149   // attach new constant pool to klass
3150   scratch_class->set_constants(scratch_cp());
3151 
3152   int i;  // for portability
3153 
3154   // update each field in klass to use new constant pool indices as needed
3155   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3156     jshort cur_index = fs.name_index();
3157     jshort new_index = find_new_index(cur_index);
3158     if (new_index != 0) {
3159       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3160         ("field-name_index change: %d to %d", cur_index, new_index));
3161       fs.set_name_index(new_index);
3162     }
3163     cur_index = fs.signature_index();
3164     new_index = find_new_index(cur_index);
3165     if (new_index != 0) {
3166       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3167         ("field-signature_index change: %d to %d", cur_index, new_index));
3168       fs.set_signature_index(new_index);
3169     }
3170     cur_index = fs.initval_index();
3171     new_index = find_new_index(cur_index);
3172     if (new_index != 0) {
3173       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3174         ("field-initval_index change: %d to %d", cur_index, new_index));
3175       fs.set_initval_index(new_index);
3176     }
3177     cur_index = fs.generic_signature_index();
3178     new_index = find_new_index(cur_index);
3179     if (new_index != 0) {
3180       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3181         ("field-generic_signature change: %d to %d", cur_index, new_index));
3182       fs.set_generic_signature_index(new_index);
3183     }
3184   } // end for each field
3185 
3186   // Update constant pool indices in the inner classes info to use
3187   // new constant indices as needed. The inner classes info is a
3188   // quadruple:
3189   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3190   InnerClassesIterator iter(scratch_class);
3191   for (; !iter.done(); iter.next()) {
3192     int cur_index = iter.inner_class_info_index();
3193     if (cur_index == 0) {
3194       continue;  // JVM spec. allows null inner class refs so skip it
3195     }
3196     int new_index = find_new_index(cur_index);
3197     if (new_index != 0) {
3198       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3199         ("inner_class_info change: %d to %d", cur_index, new_index));
3200       iter.set_inner_class_info_index(new_index);
3201     }
3202     cur_index = iter.outer_class_info_index();
3203     new_index = find_new_index(cur_index);
3204     if (new_index != 0) {
3205       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3206         ("outer_class_info change: %d to %d", cur_index, new_index));
3207       iter.set_outer_class_info_index(new_index);
3208     }
3209     cur_index = iter.inner_name_index();
3210     new_index = find_new_index(cur_index);
3211     if (new_index != 0) {
3212       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3213         ("inner_name change: %d to %d", cur_index, new_index));
3214       iter.set_inner_name_index(new_index);
3215     }
3216   } // end for each inner class
3217 
3218   // Attach each method in klass to the new constant pool and update
3219   // to use new constant pool indices as needed:
3220   Array<Method*>* methods = scratch_class->methods();
3221   for (i = methods->length() - 1; i >= 0; i--) {
3222     methodHandle method(THREAD, methods->at(i));
3223     method->set_constants(scratch_cp());
3224 
3225     int new_index = find_new_index(method->name_index());
3226     if (new_index != 0) {
3227       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3228         ("method-name_index change: %d to %d", method->name_index(),
3229         new_index));
3230       method->set_name_index(new_index);
3231     }
3232     new_index = find_new_index(method->signature_index());
3233     if (new_index != 0) {
3234       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3235         ("method-signature_index change: %d to %d",
3236         method->signature_index(), new_index));
3237       method->set_signature_index(new_index);
3238     }
3239     new_index = find_new_index(method->generic_signature_index());
3240     if (new_index != 0) {
3241       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3242         ("method-generic_signature_index change: %d to %d",
3243         method->generic_signature_index(), new_index));
3244       method->set_generic_signature_index(new_index);
3245     }
3246 
3247     // Update constant pool indices in the method's checked exception
3248     // table to use new constant indices as needed.
3249     int cext_length = method->checked_exceptions_length();
3250     if (cext_length > 0) {
3251       CheckedExceptionElement * cext_table =
3252         method->checked_exceptions_start();
3253       for (int j = 0; j < cext_length; j++) {
3254         int cur_index = cext_table[j].class_cp_index;
3255         int new_index = find_new_index(cur_index);
3256         if (new_index != 0) {
3257           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3258             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
3259           cext_table[j].class_cp_index = (u2)new_index;
3260         }
3261       } // end for each checked exception table entry
3262     } // end if there are checked exception table entries
3263 
3264     // Update each catch type index in the method's exception table
3265     // to use new constant pool indices as needed. The exception table
3266     // holds quadruple entries of the form:
3267     //   (beg_bci, end_bci, handler_bci, klass_index)
3268 
3269     ExceptionTable ex_table(method());
3270     int ext_length = ex_table.length();
3271 
3272     for (int j = 0; j < ext_length; j ++) {
3273       int cur_index = ex_table.catch_type_index(j);
3274       int new_index = find_new_index(cur_index);
3275       if (new_index != 0) {
3276         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3277           ("ext-klass_index change: %d to %d", cur_index, new_index));
3278         ex_table.set_catch_type_index(j, new_index);
3279       }
3280     } // end for each exception table entry
3281 
3282     // Update constant pool indices in the method's local variable
3283     // table to use new constant indices as needed. The local variable
3284     // table hold sextuple entries of the form:
3285     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3286     int lvt_length = method->localvariable_table_length();
3287     if (lvt_length > 0) {
3288       LocalVariableTableElement * lv_table =
3289         method->localvariable_table_start();
3290       for (int j = 0; j < lvt_length; j++) {
3291         int cur_index = lv_table[j].name_cp_index;
3292         int new_index = find_new_index(cur_index);
3293         if (new_index != 0) {
3294           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3295             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
3296           lv_table[j].name_cp_index = (u2)new_index;
3297         }
3298         cur_index = lv_table[j].descriptor_cp_index;
3299         new_index = find_new_index(cur_index);
3300         if (new_index != 0) {
3301           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3302             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
3303             new_index));
3304           lv_table[j].descriptor_cp_index = (u2)new_index;
3305         }
3306         cur_index = lv_table[j].signature_cp_index;
3307         new_index = find_new_index(cur_index);
3308         if (new_index != 0) {
3309           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3310             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
3311           lv_table[j].signature_cp_index = (u2)new_index;
3312         }
3313       } // end for each local variable table entry
3314     } // end if there are local variable table entries
3315 
3316     rewrite_cp_refs_in_stack_map_table(method, THREAD);
3317   } // end for each method
3318 } // end set_new_constant_pool()
3319 
3320 
3321 // Unevolving classes may point to methods of the_class directly
3322 // from their constant pool caches, itables, and/or vtables. We
3323 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3324 // to fix up these pointers.
3325 
3326 // Adjust cpools and vtables closure
3327 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3328 
3329   // This is a very busy routine. We don't want too much tracing
3330   // printed out.
3331   bool trace_name_printed = false;
3332   InstanceKlass *the_class = InstanceKlass::cast(_the_class_oop);
3333 
3334   // Very noisy: only enable this call if you are trying to determine
3335   // that a specific class gets found by this routine.
3336   // RC_TRACE macro has an embedded ResourceMark
3337   // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
3338   //   ("adjust check: name=%s", k->external_name()));
3339   // trace_name_printed = true;
3340 
3341   // If the class being redefined is java.lang.Object, we need to fix all
3342   // array class vtables also
3343   if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
3344     k->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3345 
3346   } else if (k->oop_is_instance()) {
3347     HandleMark hm(_thread);
3348     InstanceKlass *ik = InstanceKlass::cast(k);
3349 
3350     // HotSpot specific optimization! HotSpot does not currently
3351     // support delegation from the bootstrap class loader to a
3352     // user-defined class loader. This means that if the bootstrap
3353     // class loader is the initiating class loader, then it will also
3354     // be the defining class loader. This also means that classes
3355     // loaded by the bootstrap class loader cannot refer to classes
3356     // loaded by a user-defined class loader. Note: a user-defined
3357     // class loader can delegate to the bootstrap class loader.
3358     //
3359     // If the current class being redefined has a user-defined class
3360     // loader as its defining class loader, then we can skip all
3361     // classes loaded by the bootstrap class loader.
3362     bool is_user_defined =
3363            InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
3364     if (is_user_defined && ik->class_loader() == NULL) {
3365       return;
3366     }
3367 
3368     // Fix the vtable embedded in the_class and subclasses of the_class,
3369     // if one exists. We discard scratch_class and we don't keep an
3370     // InstanceKlass around to hold obsolete methods so we don't have
3371     // any other InstanceKlass embedded vtables to update. The vtable
3372     // holds the Method*s for virtual (but not final) methods.
3373     // Default methods, or concrete methods in interfaces are stored
3374     // in the vtable, so if an interface changes we need to check
3375     // adjust_method_entries() for every InstanceKlass, which will also
3376     // adjust the default method vtable indices.
3377     // We also need to adjust any default method entries that are
3378     // not yet in the vtable, because the vtable setup is in progress.
3379     // This must be done after we adjust the default_methods and
3380     // default_vtable_indices for methods already in the vtable.
3381     if (ik->vtable_length() > 0 && (_the_class_oop->is_interface()
3382         || ik->is_subtype_of(_the_class_oop))) {
3383       // ik->vtable() creates a wrapper object; rm cleans it up
3384       ResourceMark rm(_thread);
3385 
3386       ik->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3387       ik->adjust_default_methods(the_class, &trace_name_printed);
3388     }
3389 
3390     // If the current class has an itable and we are either redefining an
3391     // interface or if the current class is a subclass of the_class, then
3392     // we potentially have to fix the itable. If we are redefining an
3393     // interface, then we have to call adjust_method_entries() for
3394     // every InstanceKlass that has an itable since there isn't a
3395     // subclass relationship between an interface and an InstanceKlass.
3396     if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
3397         || ik->is_subclass_of(_the_class_oop))) {
3398       // ik->itable() creates a wrapper object; rm cleans it up
3399       ResourceMark rm(_thread);
3400 
3401       ik->itable()->adjust_method_entries(the_class, &trace_name_printed);
3402     }
3403 
3404     // The constant pools in other classes (other_cp) can refer to
3405     // methods in the_class. We have to update method information in
3406     // other_cp's cache. If other_cp has a previous version, then we
3407     // have to repeat the process for each previous version. The
3408     // constant pool cache holds the Method*s for non-virtual
3409     // methods and for virtual, final methods.
3410     //
3411     // Special case: if the current class is the_class, then new_cp
3412     // has already been attached to the_class and old_cp has already
3413     // been added as a previous version. The new_cp doesn't have any
3414     // cached references to old methods so it doesn't need to be
3415     // updated. We can simply start with the previous version(s) in
3416     // that case.
3417     constantPoolHandle other_cp;
3418     ConstantPoolCache* cp_cache;
3419 
3420     if (ik != _the_class_oop) {
3421       // this klass' constant pool cache may need adjustment
3422       other_cp = constantPoolHandle(ik->constants());
3423       cp_cache = other_cp->cache();
3424       if (cp_cache != NULL) {
3425         cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3426       }
3427     }
3428 
3429     // the previous versions' constant pool caches may need adjustment
3430     PreviousVersionWalker pvw(_thread, ik);
3431     for (PreviousVersionNode * pv_node = pvw.next_previous_version();
3432          pv_node != NULL; pv_node = pvw.next_previous_version()) {
3433       other_cp = pv_node->prev_constant_pool();
3434       cp_cache = other_cp->cache();
3435       if (cp_cache != NULL) {
3436         cp_cache->adjust_method_entries(other_cp->pool_holder(), &trace_name_printed);
3437       }
3438     }
3439   }
3440 }
3441 
3442 void VM_RedefineClasses::update_jmethod_ids() {
3443   for (int j = 0; j < _matching_methods_length; ++j) {
3444     Method* old_method = _matching_old_methods[j];
3445     jmethodID jmid = old_method->find_jmethod_id_or_null();
3446     if (jmid != NULL) {
3447       // There is a jmethodID, change it to point to the new method
3448       methodHandle new_method_h(_matching_new_methods[j]);
3449       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3450       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3451              "should be replaced");
3452     }
3453   }
3454 }
3455 
3456 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
3457        BitMap *emcp_methods, int * emcp_method_count_p) {
3458   *emcp_method_count_p = 0;
3459   int obsolete_count = 0;
3460   int old_index = 0;
3461   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3462     Method* old_method = _matching_old_methods[j];
3463     Method* new_method = _matching_new_methods[j];
3464     Method* old_array_method;
3465 
3466     // Maintain an old_index into the _old_methods array by skipping
3467     // deleted methods
3468     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3469       ++old_index;
3470     }
3471 
3472     if (MethodComparator::methods_EMCP(old_method, new_method)) {
3473       // The EMCP definition from JSR-163 requires the bytecodes to be
3474       // the same with the exception of constant pool indices which may
3475       // differ. However, the constants referred to by those indices
3476       // must be the same.
3477       //
3478       // We use methods_EMCP() for comparison since constant pool
3479       // merging can remove duplicate constant pool entries that were
3480       // present in the old method and removed from the rewritten new
3481       // method. A faster binary comparison function would consider the
3482       // old and new methods to be different when they are actually
3483       // EMCP.
3484       //
3485       // The old and new methods are EMCP and you would think that we
3486       // could get rid of one of them here and now and save some space.
3487       // However, the concept of EMCP only considers the bytecodes and
3488       // the constant pool entries in the comparison. Other things,
3489       // e.g., the line number table (LNT) or the local variable table
3490       // (LVT) don't count in the comparison. So the new (and EMCP)
3491       // method can have a new LNT that we need so we can't just
3492       // overwrite the new method with the old method.
3493       //
3494       // When this routine is called, we have already attached the new
3495       // methods to the_class so the old methods are effectively
3496       // overwritten. However, if an old method is still executing,
3497       // then the old method cannot be collected until sometime after
3498       // the old method call has returned. So the overwriting of old
3499       // methods by new methods will save us space except for those
3500       // (hopefully few) old methods that are still executing.
3501       //
3502       // A method refers to a ConstMethod* and this presents another
3503       // possible avenue to space savings. The ConstMethod* in the
3504       // new method contains possibly new attributes (LNT, LVT, etc).
3505       // At first glance, it seems possible to save space by replacing
3506       // the ConstMethod* in the old method with the ConstMethod*
3507       // from the new method. The old and new methods would share the
3508       // same ConstMethod* and we would save the space occupied by
3509       // the old ConstMethod*. However, the ConstMethod* contains
3510       // a back reference to the containing method. Sharing the
3511       // ConstMethod* between two methods could lead to confusion in
3512       // the code that uses the back reference. This would lead to
3513       // brittle code that could be broken in non-obvious ways now or
3514       // in the future.
3515       //
3516       // Another possibility is to copy the ConstMethod* from the new
3517       // method to the old method and then overwrite the new method with
3518       // the old method. Since the ConstMethod* contains the bytecodes
3519       // for the method embedded in the oop, this option would change
3520       // the bytecodes out from under any threads executing the old
3521       // method and make the thread's bcp invalid. Since EMCP requires
3522       // that the bytecodes be the same modulo constant pool indices, it
3523       // is straight forward to compute the correct new bcp in the new
3524       // ConstMethod* from the old bcp in the old ConstMethod*. The
3525       // time consuming part would be searching all the frames in all
3526       // of the threads to find all of the calls to the old method.
3527       //
3528       // It looks like we will have to live with the limited savings
3529       // that we get from effectively overwriting the old methods
3530       // when the new methods are attached to the_class.
3531 
3532       // track which methods are EMCP for add_previous_version() call
3533       emcp_methods->set_bit(old_index);
3534       (*emcp_method_count_p)++;
3535 
3536       // An EMCP method is _not_ obsolete. An obsolete method has a
3537       // different jmethodID than the current method. An EMCP method
3538       // has the same jmethodID as the current method. Having the
3539       // same jmethodID for all EMCP versions of a method allows for
3540       // a consistent view of the EMCP methods regardless of which
3541       // EMCP method you happen to have in hand. For example, a
3542       // breakpoint set in one EMCP method will work for all EMCP
3543       // versions of the method including the current one.
3544     } else {
3545       // mark obsolete methods as such
3546       old_method->set_is_obsolete();
3547       obsolete_count++;
3548 
3549       // obsolete methods need a unique idnum so they become new entries in
3550       // the jmethodID cache in InstanceKlass
3551       assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3552       u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
3553       if (num != ConstMethod::UNSET_IDNUM) {
3554         old_method->set_method_idnum(num);
3555       }
3556 
3557       // With tracing we try not to "yack" too much. The position of
3558       // this trace assumes there are fewer obsolete methods than
3559       // EMCP methods.
3560       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
3561         old_method->name()->as_C_string(),
3562         old_method->signature()->as_C_string()));
3563     }
3564     old_method->set_is_old();
3565   }
3566   for (int i = 0; i < _deleted_methods_length; ++i) {
3567     Method* old_method = _deleted_methods[i];
3568 
3569     assert(!old_method->has_vtable_index(),
3570            "cannot delete methods with vtable entries");;
3571 
3572     // Mark all deleted methods as old, obsolete and deleted
3573     old_method->set_is_deleted();
3574     old_method->set_is_old();
3575     old_method->set_is_obsolete();
3576     ++obsolete_count;
3577     // With tracing we try not to "yack" too much. The position of
3578     // this trace assumes there are fewer obsolete methods than
3579     // EMCP methods.
3580     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
3581                           old_method->name()->as_C_string(),
3582                           old_method->signature()->as_C_string()));
3583   }
3584   assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
3585     "sanity check");
3586   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
3587     obsolete_count));
3588 }
3589 
3590 // This internal class transfers the native function registration from old methods
3591 // to new methods.  It is designed to handle both the simple case of unchanged
3592 // native methods and the complex cases of native method prefixes being added and/or
3593 // removed.
3594 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3595 //
3596 // This class is used after the new methods have been installed in "the_class".
3597 //
3598 // So, for example, the following must be handled.  Where 'm' is a method and
3599 // a number followed by an underscore is a prefix.
3600 //
3601 //                                      Old Name    New Name
3602 // Simple transfer to new method        m       ->  m
3603 // Add prefix                           m       ->  1_m
3604 // Remove prefix                        1_m     ->  m
3605 // Simultaneous add of prefixes         m       ->  3_2_1_m
3606 // Simultaneous removal of prefixes     3_2_1_m ->  m
3607 // Simultaneous add and remove          1_m     ->  2_m
3608 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
3609 //
3610 class TransferNativeFunctionRegistration {
3611  private:
3612   instanceKlassHandle the_class;
3613   int prefix_count;
3614   char** prefixes;
3615 
3616   // Recursively search the binary tree of possibly prefixed method names.
3617   // Iteration could be used if all agents were well behaved. Full tree walk is
3618   // more resilent to agents not cleaning up intermediate methods.
3619   // Branch at each depth in the binary tree is:
3620   //    (1) without the prefix.
3621   //    (2) with the prefix.
3622   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3623   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3624                                      Symbol* signature) {
3625     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3626     if (name_symbol != NULL) {
3627       Method* method = the_class()->lookup_method(name_symbol, signature);
3628       if (method != NULL) {
3629         // Even if prefixed, intermediate methods must exist.
3630         if (method->is_native()) {
3631           // Wahoo, we found a (possibly prefixed) version of the method, return it.
3632           return method;
3633         }
3634         if (depth < prefix_count) {
3635           // Try applying further prefixes (other than this one).
3636           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3637           if (method != NULL) {
3638             return method; // found
3639           }
3640 
3641           // Try adding this prefix to the method name and see if it matches
3642           // another method name.
3643           char* prefix = prefixes[depth];
3644           size_t prefix_len = strlen(prefix);
3645           size_t trial_len = name_len + prefix_len;
3646           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3647           strcpy(trial_name_str, prefix);
3648           strcat(trial_name_str, name_str);
3649           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3650                                             signature);
3651           if (method != NULL) {
3652             // If found along this branch, it was prefixed, mark as such
3653             method->set_is_prefixed_native();
3654             return method; // found
3655           }
3656         }
3657       }
3658     }
3659     return NULL;  // This whole branch bore nothing
3660   }
3661 
3662   // Return the method name with old prefixes stripped away.
3663   char* method_name_without_prefixes(Method* method) {
3664     Symbol* name = method->name();
3665     char* name_str = name->as_utf8();
3666 
3667     // Old prefixing may be defunct, strip prefixes, if any.
3668     for (int i = prefix_count-1; i >= 0; i--) {
3669       char* prefix = prefixes[i];
3670       size_t prefix_len = strlen(prefix);
3671       if (strncmp(prefix, name_str, prefix_len) == 0) {
3672         name_str += prefix_len;
3673       }
3674     }
3675     return name_str;
3676   }
3677 
3678   // Strip any prefixes off the old native method, then try to find a
3679   // (possibly prefixed) new native that matches it.
3680   Method* strip_and_search_for_new_native(Method* method) {
3681     ResourceMark rm;
3682     char* name_str = method_name_without_prefixes(method);
3683     return search_prefix_name_space(0, name_str, strlen(name_str),
3684                                     method->signature());
3685   }
3686 
3687  public:
3688 
3689   // Construct a native method transfer processor for this class.
3690   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
3691     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3692 
3693     the_class = _the_class;
3694     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3695   }
3696 
3697   // Attempt to transfer any of the old or deleted methods that are native
3698   void transfer_registrations(Method** old_methods, int methods_length) {
3699     for (int j = 0; j < methods_length; j++) {
3700       Method* old_method = old_methods[j];
3701 
3702       if (old_method->is_native() && old_method->has_native_function()) {
3703         Method* new_method = strip_and_search_for_new_native(old_method);
3704         if (new_method != NULL) {
3705           // Actually set the native function in the new method.
3706           // Redefine does not send events (except CFLH), certainly not this
3707           // behind the scenes re-registration.
3708           new_method->set_native_function(old_method->native_function(),
3709                               !Method::native_bind_event_is_interesting);
3710         }
3711       }
3712     }
3713   }
3714 };
3715 
3716 // Don't lose the association between a native method and its JNI function.
3717 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
3718   TransferNativeFunctionRegistration transfer(the_class);
3719   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3720   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3721 }
3722 
3723 // Deoptimize all compiled code that depends on this class.
3724 //
3725 // If the can_redefine_classes capability is obtained in the onload
3726 // phase then the compiler has recorded all dependencies from startup.
3727 // In that case we need only deoptimize and throw away all compiled code
3728 // that depends on the class.
3729 //
3730 // If can_redefine_classes is obtained sometime after the onload
3731 // phase then the dependency information may be incomplete. In that case
3732 // the first call to RedefineClasses causes all compiled code to be
3733 // thrown away. As can_redefine_classes has been obtained then
3734 // all future compilations will record dependencies so second and
3735 // subsequent calls to RedefineClasses need only throw away code
3736 // that depends on the class.
3737 //
3738 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
3739   assert_locked_or_safepoint(Compile_lock);
3740 
3741   // All dependencies have been recorded from startup or this is a second or
3742   // subsequent use of RedefineClasses
3743   if (JvmtiExport::all_dependencies_are_recorded()) {
3744     Universe::flush_evol_dependents_on(k_h);
3745   } else {
3746     CodeCache::mark_all_nmethods_for_deoptimization();
3747 
3748     ResourceMark rm(THREAD);
3749     DeoptimizationMarker dm;
3750 
3751     // Deoptimize all activations depending on marked nmethods
3752     Deoptimization::deoptimize_dependents();
3753 
3754     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
3755     CodeCache::make_marked_nmethods_not_entrant();
3756 
3757     // From now on we know that the dependency information is complete
3758     JvmtiExport::set_all_dependencies_are_recorded(true);
3759   }
3760 }
3761 
3762 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3763   Method* old_method;
3764   Method* new_method;
3765 
3766   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3767   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3768   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3769   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3770 
3771   _matching_methods_length = 0;
3772   _deleted_methods_length  = 0;
3773   _added_methods_length    = 0;
3774 
3775   int nj = 0;
3776   int oj = 0;
3777   while (true) {
3778     if (oj >= _old_methods->length()) {
3779       if (nj >= _new_methods->length()) {
3780         break; // we've looked at everything, done
3781       }
3782       // New method at the end
3783       new_method = _new_methods->at(nj);
3784       _added_methods[_added_methods_length++] = new_method;
3785       ++nj;
3786     } else if (nj >= _new_methods->length()) {
3787       // Old method, at the end, is deleted
3788       old_method = _old_methods->at(oj);
3789       _deleted_methods[_deleted_methods_length++] = old_method;
3790       ++oj;
3791     } else {
3792       old_method = _old_methods->at(oj);
3793       new_method = _new_methods->at(nj);
3794       if (old_method->name() == new_method->name()) {
3795         if (old_method->signature() == new_method->signature()) {
3796           _matching_old_methods[_matching_methods_length  ] = old_method;
3797           _matching_new_methods[_matching_methods_length++] = new_method;
3798           ++nj;
3799           ++oj;
3800         } else {
3801           // added overloaded have already been moved to the end,
3802           // so this is a deleted overloaded method
3803           _deleted_methods[_deleted_methods_length++] = old_method;
3804           ++oj;
3805         }
3806       } else { // names don't match
3807         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3808           // new method
3809           _added_methods[_added_methods_length++] = new_method;
3810           ++nj;
3811         } else {
3812           // deleted method
3813           _deleted_methods[_deleted_methods_length++] = old_method;
3814           ++oj;
3815         }
3816       }
3817     }
3818   }
3819   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3820   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3821 }
3822 
3823 
3824 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
3825                                           instanceKlassHandle scratch_class) {
3826   // Swap annotation fields values
3827   Annotations* old_annotations = the_class->annotations();
3828   the_class->set_annotations(scratch_class->annotations());
3829   scratch_class->set_annotations(old_annotations);
3830 }
3831 
3832 
3833 // Install the redefinition of a class:
3834 //    - house keeping (flushing breakpoints and caches, deoptimizing
3835 //      dependent compiled code)
3836 //    - replacing parts in the_class with parts from scratch_class
3837 //    - adding a weak reference to track the obsolete but interesting
3838 //      parts of the_class
3839 //    - adjusting constant pool caches and vtables in other classes
3840 //      that refer to methods in the_class. These adjustments use the
3841 //      ClassLoaderDataGraph::classes_do() facility which only allows
3842 //      a helper method to be specified. The interesting parameters
3843 //      that we would like to pass to the helper method are saved in
3844 //      static global fields in the VM operation.
3845 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3846        Klass* scratch_class_oop, TRAPS) {
3847 
3848   HandleMark hm(THREAD);   // make sure handles from this call are freed
3849   RC_TIMER_START(_timer_rsc_phase1);
3850 
3851   instanceKlassHandle scratch_class(scratch_class_oop);
3852 
3853   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3854   Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
3855   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3856 
3857   // Remove all breakpoints in methods of this class
3858   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3859   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3860 
3861   // Deoptimize all compiled code that depends on this class
3862   flush_dependent_code(the_class, THREAD);
3863 
3864   _old_methods = the_class->methods();
3865   _new_methods = scratch_class->methods();
3866   _the_class_oop = the_class_oop;
3867   compute_added_deleted_matching_methods();
3868   update_jmethod_ids();
3869 
3870   // Attach new constant pool to the original klass. The original
3871   // klass still refers to the old constant pool (for now).
3872   scratch_class->constants()->set_pool_holder(the_class());
3873 
3874 #if 0
3875   // In theory, with constant pool merging in place we should be able
3876   // to save space by using the new, merged constant pool in place of
3877   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3878   // the klass version we are replacing now and any constant pool(s) in
3879   // previous versions of klass. Nice theory, doesn't work in practice.
3880   // When this code is enabled, even simple programs throw NullPointer
3881   // exceptions. I'm guessing that this is caused by some constant pool
3882   // cache difference between the new, merged constant pool and the
3883   // constant pool that was just being used by the klass. I'm keeping
3884   // this code around to archive the idea, but the code has to remain
3885   // disabled for now.
3886 
3887   // Attach each old method to the new constant pool. This can be
3888   // done here since we are past the bytecode verification and
3889   // constant pool optimization phases.
3890   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3891     Method* method = _old_methods->at(i);
3892     method->set_constants(scratch_class->constants());
3893   }
3894 
3895   {
3896     // walk all previous versions of the klass
3897     InstanceKlass *ik = (InstanceKlass *)the_class();
3898     PreviousVersionWalker pvw(ik);
3899     instanceKlassHandle ikh;
3900     do {
3901       ikh = pvw.next_previous_version();
3902       if (!ikh.is_null()) {
3903         ik = ikh();
3904 
3905         // attach previous version of klass to the new constant pool
3906         ik->set_constants(scratch_class->constants());
3907 
3908         // Attach each method in the previous version of klass to the
3909         // new constant pool
3910         Array<Method*>* prev_methods = ik->methods();
3911         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3912           Method* method = prev_methods->at(i);
3913           method->set_constants(scratch_class->constants());
3914         }
3915       }
3916     } while (!ikh.is_null());
3917   }
3918 #endif
3919 
3920   // Replace methods and constantpool
3921   the_class->set_methods(_new_methods);
3922   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3923                                           // and to be able to undo operation easily.
3924 
3925   ConstantPool* old_constants = the_class->constants();
3926   the_class->set_constants(scratch_class->constants());
3927   scratch_class->set_constants(old_constants);  // See the previous comment.
3928 #if 0
3929   // We are swapping the guts of "the new class" with the guts of "the
3930   // class". Since the old constant pool has just been attached to "the
3931   // new class", it seems logical to set the pool holder in the old
3932   // constant pool also. However, doing this will change the observable
3933   // class hierarchy for any old methods that are still executing. A
3934   // method can query the identity of its "holder" and this query uses
3935   // the method's constant pool link to find the holder. The change in
3936   // holding class from "the class" to "the new class" can confuse
3937   // things.
3938   //
3939   // Setting the old constant pool's holder will also cause
3940   // verification done during vtable initialization below to fail.
3941   // During vtable initialization, the vtable's class is verified to be
3942   // a subtype of the method's holder. The vtable's class is "the
3943   // class" and the method's holder is gotten from the constant pool
3944   // link in the method itself. For "the class"'s directly implemented
3945   // methods, the method holder is "the class" itself (as gotten from
3946   // the new constant pool). The check works fine in this case. The
3947   // check also works fine for methods inherited from super classes.
3948   //
3949   // Miranda methods are a little more complicated. A miranda method is
3950   // provided by an interface when the class implementing the interface
3951   // does not provide its own method.  These interfaces are implemented
3952   // internally as an InstanceKlass. These special instanceKlasses
3953   // share the constant pool of the class that "implements" the
3954   // interface. By sharing the constant pool, the method holder of a
3955   // miranda method is the class that "implements" the interface. In a
3956   // non-redefine situation, the subtype check works fine. However, if
3957   // the old constant pool's pool holder is modified, then the check
3958   // fails because there is no class hierarchy relationship between the
3959   // vtable's class and "the new class".
3960 
3961   old_constants->set_pool_holder(scratch_class());
3962 #endif
3963 
3964   // track which methods are EMCP for add_previous_version() call below
3965   BitMap emcp_methods(_old_methods->length());
3966   int emcp_method_count = 0;
3967   emcp_methods.clear();  // clears 0..(length() - 1)
3968   check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3969   transfer_old_native_function_registrations(the_class);
3970 
3971   // The class file bytes from before any retransformable agents mucked
3972   // with them was cached on the scratch class, move to the_class.
3973   // Note: we still want to do this if nothing needed caching since it
3974   // should get cleared in the_class too.
3975   if (the_class->get_cached_class_file_bytes() == 0) {
3976     // the_class doesn't have a cache yet so copy it
3977     the_class->set_cached_class_file(scratch_class->get_cached_class_file());
3978   }
3979   else if (scratch_class->get_cached_class_file_bytes() !=
3980            the_class->get_cached_class_file_bytes()) {
3981     // The same class can be present twice in the scratch classes list or there
3982     // are multiple concurrent RetransformClasses calls on different threads.
3983     // In such cases we have to deallocate scratch_class cached_class_file_bytes.
3984     os::free(scratch_class->get_cached_class_file_bytes());
3985   }
3986 
3987   // NULL out in scratch class to not delete twice.  The class to be redefined
3988   // always owns these bytes.
3989   scratch_class->set_cached_class_file(NULL);
3990 
3991   // Replace inner_classes
3992   Array<u2>* old_inner_classes = the_class->inner_classes();
3993   the_class->set_inner_classes(scratch_class->inner_classes());
3994   scratch_class->set_inner_classes(old_inner_classes);
3995 
3996   // Initialize the vtable and interface table after
3997   // methods have been rewritten
3998   {
3999     ResourceMark rm(THREAD);
4000     // no exception should happen here since we explicitly
4001     // do not check loader constraints.
4002     // compare_and_normalize_class_versions has already checked:
4003     //  - classloaders unchanged, signatures unchanged
4004     //  - all instanceKlasses for redefined classes reused & contents updated
4005     the_class->vtable()->initialize_vtable(false, THREAD);
4006     the_class->itable()->initialize_itable(false, THREAD);
4007     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4008   }
4009 
4010   // Leave arrays of jmethodIDs and itable index cache unchanged
4011 
4012   // Copy the "source file name" attribute from new class version
4013   the_class->set_source_file_name_index(
4014     scratch_class->source_file_name_index());
4015 
4016   // Copy the "source debug extension" attribute from new class version
4017   the_class->set_source_debug_extension(
4018     scratch_class->source_debug_extension(),
4019     scratch_class->source_debug_extension() == NULL ? 0 :
4020     (int)strlen(scratch_class->source_debug_extension()));
4021 
4022   // Use of javac -g could be different in the old and the new
4023   if (scratch_class->access_flags().has_localvariable_table() !=
4024       the_class->access_flags().has_localvariable_table()) {
4025 
4026     AccessFlags flags = the_class->access_flags();
4027     if (scratch_class->access_flags().has_localvariable_table()) {
4028       flags.set_has_localvariable_table();
4029     } else {
4030       flags.clear_has_localvariable_table();
4031     }
4032     the_class->set_access_flags(flags);
4033   }
4034 
4035   swap_annotations(the_class, scratch_class);
4036 
4037   // Replace minor version number of class file
4038   u2 old_minor_version = the_class->minor_version();
4039   the_class->set_minor_version(scratch_class->minor_version());
4040   scratch_class->set_minor_version(old_minor_version);
4041 
4042   // Replace major version number of class file
4043   u2 old_major_version = the_class->major_version();
4044   the_class->set_major_version(scratch_class->major_version());
4045   scratch_class->set_major_version(old_major_version);
4046 
4047   // Replace CP indexes for class and name+type of enclosing method
4048   u2 old_class_idx  = the_class->enclosing_method_class_index();
4049   u2 old_method_idx = the_class->enclosing_method_method_index();
4050   the_class->set_enclosing_method_indices(
4051     scratch_class->enclosing_method_class_index(),
4052     scratch_class->enclosing_method_method_index());
4053   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4054 
4055   // keep track of previous versions of this class
4056   the_class->add_previous_version(scratch_class, &emcp_methods,
4057     emcp_method_count);
4058 
4059   RC_TIMER_STOP(_timer_rsc_phase1);
4060   RC_TIMER_START(_timer_rsc_phase2);
4061 
4062   // Adjust constantpool caches and vtables for all classes
4063   // that reference methods of the evolved class.
4064   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4065   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4066 
4067   // JSR-292 support
4068   MemberNameTable* mnt = the_class->member_names();
4069   if (mnt != NULL) {
4070     bool trace_name_printed = false;
4071     mnt->adjust_method_entries(the_class(), &trace_name_printed);
4072   }
4073 
4074   // Fix Resolution Error table also to remove old constant pools
4075   SystemDictionary::delete_resolution_error(old_constants);
4076 
4077   if (the_class->oop_map_cache() != NULL) {
4078     // Flush references to any obsolete methods from the oop map cache
4079     // so that obsolete methods are not pinned.
4080     the_class->oop_map_cache()->flush_obsolete_entries();
4081   }
4082 
4083   // increment the classRedefinedCount field in the_class and in any
4084   // direct and indirect subclasses of the_class
4085   increment_class_counter((InstanceKlass *)the_class(), THREAD);
4086 
4087   // RC_TRACE macro has an embedded ResourceMark
4088   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
4089     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4090     the_class->external_name(),
4091     java_lang_Class::classRedefinedCount(the_class_mirror),
4092     os::available_memory() >> 10));
4093 
4094   RC_TIMER_STOP(_timer_rsc_phase2);
4095 } // end redefine_single_class()
4096 
4097 
4098 // Increment the classRedefinedCount field in the specific InstanceKlass
4099 // and in all direct and indirect subclasses.
4100 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4101   oop class_mirror = ik->java_mirror();
4102   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4103   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4104   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4105 
4106   if (class_oop != _the_class_oop) {
4107     // _the_class_oop count is printed at end of redefine_single_class()
4108     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
4109       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
4110   }
4111 
4112   for (Klass *subk = ik->subklass(); subk != NULL;
4113        subk = subk->next_sibling()) {
4114     if (subk->oop_is_instance()) {
4115       // Only update instanceKlasses
4116       InstanceKlass *subik = (InstanceKlass*)subk;
4117       // recursively do subclasses of the current subclass
4118       increment_class_counter(subik, THREAD);
4119     }
4120   }
4121 }
4122 
4123 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4124   bool no_old_methods = true;  // be optimistic
4125 
4126   // Both array and instance classes have vtables.
4127   // a vtable should never contain old or obsolete methods
4128   ResourceMark rm(_thread);
4129   if (k->vtable_length() > 0 &&
4130       !k->vtable()->check_no_old_or_obsolete_entries()) {
4131     if (RC_TRACE_ENABLED(0x00004000)) {
4132       RC_TRACE_WITH_THREAD(0x00004000, _thread,
4133         ("klassVtable::check_no_old_or_obsolete_entries failure"
4134          " -- OLD or OBSOLETE method found -- class: %s",
4135          k->signature_name()));
4136       k->vtable()->dump_vtable();
4137     }
4138     no_old_methods = false;
4139   }
4140 
4141   if (k->oop_is_instance()) {
4142     HandleMark hm(_thread);
4143     InstanceKlass *ik = InstanceKlass::cast(k);
4144 
4145     // an itable should never contain old or obsolete methods
4146     if (ik->itable_length() > 0 &&
4147         !ik->itable()->check_no_old_or_obsolete_entries()) {
4148       if (RC_TRACE_ENABLED(0x00004000)) {
4149         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4150           ("klassItable::check_no_old_or_obsolete_entries failure"
4151            " -- OLD or OBSOLETE method found -- class: %s",
4152            ik->signature_name()));
4153         ik->itable()->dump_itable();
4154       }
4155       no_old_methods = false;
4156     }
4157 
4158     // the constant pool cache should never contain non-deleted old or obsolete methods
4159     if (ik->constants() != NULL &&
4160         ik->constants()->cache() != NULL &&
4161         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4162       if (RC_TRACE_ENABLED(0x00004000)) {
4163         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4164           ("cp-cache::check_no_old_or_obsolete_entries failure"
4165            " -- OLD or OBSOLETE method found -- class: %s",
4166            ik->signature_name()));
4167         ik->constants()->cache()->dump_cache();
4168       }
4169       no_old_methods = false;
4170     }
4171   }
4172 
4173   // print and fail guarantee if old methods are found.
4174   if (!no_old_methods) {
4175     if (RC_TRACE_ENABLED(0x00004000)) {
4176       dump_methods();
4177     } else {
4178       tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
4179         "to see more info about the following guarantee() failure.");
4180     }
4181     guarantee(false, "OLD and/or OBSOLETE method(s) found");
4182   }
4183 }
4184 
4185 
4186 void VM_RedefineClasses::dump_methods() {
4187   int j;
4188   RC_TRACE(0x00004000, ("_old_methods --"));
4189   for (j = 0; j < _old_methods->length(); ++j) {
4190     Method* m = _old_methods->at(j);
4191     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4192     m->access_flags().print_on(tty);
4193     tty->print(" --  ");
4194     m->print_name(tty);
4195     tty->cr();
4196   }
4197   RC_TRACE(0x00004000, ("_new_methods --"));
4198   for (j = 0; j < _new_methods->length(); ++j) {
4199     Method* m = _new_methods->at(j);
4200     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4201     m->access_flags().print_on(tty);
4202     tty->print(" --  ");
4203     m->print_name(tty);
4204     tty->cr();
4205   }
4206   RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
4207   for (j = 0; j < _matching_methods_length; ++j) {
4208     Method* m = _matching_old_methods[j];
4209     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4210     m->access_flags().print_on(tty);
4211     tty->print(" --  ");
4212     m->print_name(tty);
4213     tty->cr();
4214     m = _matching_new_methods[j];
4215     RC_TRACE_NO_CR(0x00004000, ("      (%5d)  ", m->vtable_index()));
4216     m->access_flags().print_on(tty);
4217     tty->cr();
4218   }
4219   RC_TRACE(0x00004000, ("_deleted_methods --"));
4220   for (j = 0; j < _deleted_methods_length; ++j) {
4221     Method* m = _deleted_methods[j];
4222     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4223     m->access_flags().print_on(tty);
4224     tty->print(" --  ");
4225     m->print_name(tty);
4226     tty->cr();
4227   }
4228   RC_TRACE(0x00004000, ("_added_methods --"));
4229   for (j = 0; j < _added_methods_length; ++j) {
4230     Method* m = _added_methods[j];
4231     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4232     m->access_flags().print_on(tty);
4233     tty->print(" --  ");
4234     m->print_name(tty);
4235     tty->cr();
4236   }
4237 }