1 /*
   2  * Copyright (c) 2003, 2017, 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 "aot/aotLoader.hpp"
  27 #include "classfile/classFileStream.hpp"
  28 #include "classfile/metadataOnStackMark.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/verifier.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "compiler/compileBroker.hpp"
  33 #include "gc/shared/gcLocker.hpp"
  34 #include "interpreter/oopMapCache.hpp"
  35 #include "interpreter/rewriter.hpp"
  36 #include "logging/logStream.hpp"
  37 #include "memory/metadataFactory.hpp"
  38 #include "memory/metaspaceShared.hpp"
  39 #include "memory/resourceArea.hpp"
  40 #include "memory/universe.inline.hpp"
  41 #include "oops/fieldStreams.hpp"
  42 #include "oops/klassVtable.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "prims/jvmtiImpl.hpp"
  45 #include "prims/jvmtiRedefineClasses.hpp"
  46 #include "prims/jvmtiThreadState.inline.hpp"
  47 #include "prims/resolvedMethodTable.hpp"
  48 #include "prims/methodComparator.hpp"
  49 #include "runtime/deoptimization.hpp"
  50 #include "runtime/relocator.hpp"
  51 #include "utilities/bitMap.inline.hpp"
  52 #include "utilities/events.hpp"
  53 
  54 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
  55 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
  56 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
  57 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
  58 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
  59 Method**  VM_RedefineClasses::_added_methods        = NULL;
  60 int         VM_RedefineClasses::_matching_methods_length = 0;
  61 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  62 int         VM_RedefineClasses::_added_methods_length    = 0;
  63 Klass*      VM_RedefineClasses::_the_class = NULL;
  64 
  65 
  66 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  67                                        const jvmtiClassDefinition *class_defs,
  68                                        JvmtiClassLoadKind class_load_kind) {
  69   _class_count = class_count;
  70   _class_defs = class_defs;
  71   _class_load_kind = class_load_kind;
  72   _any_class_has_resolved_methods = false;
  73   _res = JVMTI_ERROR_NONE;
  74 }
  75 
  76 static inline InstanceKlass* get_ik(jclass def) {
  77   oop mirror = JNIHandles::resolve_non_null(def);
  78   return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
  79 }
  80 
  81 // If any of the classes are being redefined, wait
  82 // Parallel constant pool merging leads to indeterminate constant pools.
  83 void VM_RedefineClasses::lock_classes() {
  84   MutexLocker ml(RedefineClasses_lock);
  85   bool has_redefined;
  86   do {
  87     has_redefined = false;
  88     // Go through classes each time until none are being redefined.
  89     for (int i = 0; i < _class_count; i++) {
  90       if (get_ik(_class_defs[i].klass)->is_being_redefined()) {
  91         RedefineClasses_lock->wait();
  92         has_redefined = true;
  93         break;  // for loop
  94       }
  95     }
  96   } while (has_redefined);
  97   for (int i = 0; i < _class_count; i++) {
  98     get_ik(_class_defs[i].klass)->set_is_being_redefined(true);
  99   }
 100   RedefineClasses_lock->notify_all();
 101 }
 102 
 103 void VM_RedefineClasses::unlock_classes() {
 104   MutexLocker ml(RedefineClasses_lock);
 105   for (int i = 0; i < _class_count; i++) {
 106     assert(get_ik(_class_defs[i].klass)->is_being_redefined(),
 107            "should be being redefined to get here");
 108     get_ik(_class_defs[i].klass)->set_is_being_redefined(false);
 109   }
 110   RedefineClasses_lock->notify_all();
 111 }
 112 
 113 bool VM_RedefineClasses::doit_prologue() {
 114   if (_class_count == 0) {
 115     _res = JVMTI_ERROR_NONE;
 116     return false;
 117   }
 118   if (_class_defs == NULL) {
 119     _res = JVMTI_ERROR_NULL_POINTER;
 120     return false;
 121   }
 122   for (int i = 0; i < _class_count; i++) {
 123     if (_class_defs[i].klass == NULL) {
 124       _res = JVMTI_ERROR_INVALID_CLASS;
 125       return false;
 126     }
 127     if (_class_defs[i].class_byte_count == 0) {
 128       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
 129       return false;
 130     }
 131     if (_class_defs[i].class_bytes == NULL) {
 132       _res = JVMTI_ERROR_NULL_POINTER;
 133       return false;
 134     }
 135 
 136     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 137     // classes for primitives and arrays and vm anonymous classes cannot be redefined
 138     // check here so following code can assume these classes are InstanceKlass
 139     if (!is_modifiable_class(mirror)) {
 140       _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
 141       return false;
 142     }
 143   }
 144 
 145   // Start timer after all the sanity checks; not quite accurate, but
 146   // better than adding a bunch of stop() calls.
 147   if (log_is_enabled(Info, redefine, class, timer)) {
 148     _timer_vm_op_prologue.start();
 149   }
 150 
 151   lock_classes();
 152   // We first load new class versions in the prologue, because somewhere down the
 153   // call chain it is required that the current thread is a Java thread.
 154   _res = load_new_class_versions(Thread::current());
 155   if (_res != JVMTI_ERROR_NONE) {
 156     // free any successfully created classes, since none are redefined
 157     for (int i = 0; i < _class_count; i++) {
 158       if (_scratch_classes[i] != NULL) {
 159         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 160         // Free the memory for this class at class unloading time.  Not before
 161         // because CMS might think this is still live.
 162         InstanceKlass* ik = get_ik(_class_defs[i].klass);
 163         if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
 164           // Don't double-free cached_class_file copied from the original class if error.
 165           _scratch_classes[i]->set_cached_class_file(NULL);
 166         }
 167         cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
 168       }
 169     }
 170     // Free os::malloc allocated memory in load_new_class_version.
 171     os::free(_scratch_classes);
 172     _timer_vm_op_prologue.stop();
 173     unlock_classes();
 174     return false;
 175   }
 176 
 177   _timer_vm_op_prologue.stop();
 178   return true;
 179 }
 180 
 181 void VM_RedefineClasses::doit() {
 182   Thread *thread = Thread::current();
 183 
 184 #if INCLUDE_CDS
 185   if (UseSharedSpaces) {
 186     // Sharing is enabled so we remap the shared readonly space to
 187     // shared readwrite, private just in case we need to redefine
 188     // a shared class. We do the remap during the doit() phase of
 189     // the safepoint to be safer.
 190     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
 191       log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
 192       _res = JVMTI_ERROR_INTERNAL;
 193       return;
 194     }
 195   }
 196 #endif
 197 
 198   // Mark methods seen on stack and everywhere else so old methods are not
 199   // cleaned up if they're on the stack.
 200   MetadataOnStackMark md_on_stack(true);
 201   HandleMark hm(thread);   // make sure any handles created are deleted
 202                            // before the stack walk again.
 203 
 204   for (int i = 0; i < _class_count; i++) {
 205     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 206   }
 207 
 208   // Clean out MethodData pointing to old Method*
 209   // Have to do this after all classes are redefined and all methods that
 210   // are redefined are marked as old.
 211   MethodDataCleaner clean_weak_method_links;
 212   ClassLoaderDataGraph::classes_do(&clean_weak_method_links);
 213 
 214   // JSR-292 support
 215   if (_any_class_has_resolved_methods) {
 216     bool trace_name_printed = false;
 217     ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
 218   }
 219 
 220   // Disable any dependent concurrent compilations
 221   SystemDictionary::notice_modification();
 222 
 223   // Set flag indicating that some invariants are no longer true.
 224   // See jvmtiExport.hpp for detailed explanation.
 225   JvmtiExport::set_has_redefined_a_class();
 226 
 227   // check_class() is optionally called for product bits, but is
 228   // always called for non-product bits.
 229 #ifdef PRODUCT
 230   if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
 231 #endif
 232     log_trace(redefine, class, obsolete, metadata)("calling check_class");
 233     CheckClass check_class(thread);
 234     ClassLoaderDataGraph::classes_do(&check_class);
 235 #ifdef PRODUCT
 236   }
 237 #endif
 238 }
 239 
 240 void VM_RedefineClasses::doit_epilogue() {
 241   unlock_classes();
 242 
 243   // Free os::malloc allocated memory.
 244   os::free(_scratch_classes);
 245 
 246   // Reset the_class to null for error printing.
 247   _the_class = NULL;
 248 
 249   if (log_is_enabled(Info, redefine, class, timer)) {
 250     // Used to have separate timers for "doit" and "all", but the timer
 251     // overhead skewed the measurements.
 252     julong doit_time = _timer_rsc_phase1.milliseconds() +
 253                        _timer_rsc_phase2.milliseconds();
 254     julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 255 
 256     log_info(redefine, class, timer)
 257       ("vm_op: all=" JULONG_FORMAT "  prologue=" JULONG_FORMAT "  doit=" JULONG_FORMAT,
 258        all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
 259     log_info(redefine, class, timer)
 260       ("redefine_single_class: phase1=" JULONG_FORMAT "  phase2=" JULONG_FORMAT,
 261        (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
 262   }
 263 }
 264 
 265 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 266   // classes for primitives cannot be redefined
 267   if (java_lang_Class::is_primitive(klass_mirror)) {
 268     return false;
 269   }
 270   Klass* k = java_lang_Class::as_Klass(klass_mirror);
 271   // classes for arrays cannot be redefined
 272   if (k == NULL || !k->is_instance_klass()) {
 273     return false;
 274   }
 275 
 276   // Cannot redefine or retransform an anonymous class.
 277   if (InstanceKlass::cast(k)->is_anonymous()) {
 278     return false;
 279   }
 280   return true;
 281 }
 282 
 283 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 284 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 285 // direct CP entries, there is just the current entry to append. For
 286 // indirect and double-indirect CP entries, there are zero or more
 287 // referenced CP entries along with the current entry to append.
 288 // Indirect and double-indirect CP entries are handled by recursive
 289 // calls to append_entry() as needed. The referenced CP entries are
 290 // always appended to *merge_cp_p before the referee CP entry. These
 291 // referenced CP entries may already exist in *merge_cp_p in which case
 292 // there is nothing extra to append and only the current entry is
 293 // appended.
 294 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
 295        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 296        TRAPS) {
 297 
 298   // append is different depending on entry tag type
 299   switch (scratch_cp->tag_at(scratch_i).value()) {
 300 
 301     // The old verifier is implemented outside the VM. It loads classes,
 302     // but does not resolve constant pool entries directly so we never
 303     // see Class entries here with the old verifier. Similarly the old
 304     // verifier does not like Class entries in the input constant pool.
 305     // The split-verifier is implemented in the VM so it can optionally
 306     // and directly resolve constant pool entries to load classes. The
 307     // split-verifier can accept either Class entries or UnresolvedClass
 308     // entries in the input constant pool. We revert the appended copy
 309     // back to UnresolvedClass so that either verifier will be happy
 310     // with the constant pool entry.
 311     //
 312     // this is an indirect CP entry so it needs special handling
 313     case JVM_CONSTANT_Class:
 314     case JVM_CONSTANT_UnresolvedClass:
 315     {
 316       int name_i = scratch_cp->klass_name_index_at(scratch_i);
 317       int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
 318                                                      merge_cp_length_p, THREAD);
 319 
 320       if (new_name_i != name_i) {
 321         log_trace(redefine, class, constantpool)
 322           ("Class entry@%d name_index change: %d to %d",
 323            *merge_cp_length_p, name_i, new_name_i);
 324       }
 325 
 326       (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
 327       if (scratch_i != *merge_cp_length_p) {
 328         // The new entry in *merge_cp_p is at a different index than
 329         // the new entry in scratch_cp so we need to map the index values.
 330         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 331       }
 332       (*merge_cp_length_p)++;
 333     } break;
 334 
 335     // these are direct CP entries so they can be directly appended,
 336     // but double and long take two constant pool entries
 337     case JVM_CONSTANT_Double:  // fall through
 338     case JVM_CONSTANT_Long:
 339     {
 340       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 341         THREAD);
 342 
 343       if (scratch_i != *merge_cp_length_p) {
 344         // The new entry in *merge_cp_p is at a different index than
 345         // the new entry in scratch_cp so we need to map the index values.
 346         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 347       }
 348       (*merge_cp_length_p) += 2;
 349     } break;
 350 
 351     // these are direct CP entries so they can be directly appended
 352     case JVM_CONSTANT_Float:   // fall through
 353     case JVM_CONSTANT_Integer: // fall through
 354     case JVM_CONSTANT_Utf8:    // fall through
 355 
 356     // This was an indirect CP entry, but it has been changed into
 357     // Symbol*s so this entry can be directly appended.
 358     case JVM_CONSTANT_String:      // fall through
 359     {
 360       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 361         THREAD);
 362 
 363       if (scratch_i != *merge_cp_length_p) {
 364         // The new entry in *merge_cp_p is at a different index than
 365         // the new entry in scratch_cp so we need to map the index values.
 366         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 367       }
 368       (*merge_cp_length_p)++;
 369     } break;
 370 
 371     // this is an indirect CP entry so it needs special handling
 372     case JVM_CONSTANT_NameAndType:
 373     {
 374       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 375       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
 376                                                          merge_cp_length_p, THREAD);
 377 
 378       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 379       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
 380                                                               merge_cp_p, merge_cp_length_p,
 381                                                               THREAD);
 382 
 383       // If the referenced entries already exist in *merge_cp_p, then
 384       // both new_name_ref_i and new_signature_ref_i will both be 0.
 385       // In that case, all we are appending is the current entry.
 386       if (new_name_ref_i != name_ref_i) {
 387         log_trace(redefine, class, constantpool)
 388           ("NameAndType entry@%d name_ref_index change: %d to %d",
 389            *merge_cp_length_p, name_ref_i, new_name_ref_i);
 390       }
 391       if (new_signature_ref_i != signature_ref_i) {
 392         log_trace(redefine, class, constantpool)
 393           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 394            *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
 395       }
 396 
 397       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 398         new_name_ref_i, new_signature_ref_i);
 399       if (scratch_i != *merge_cp_length_p) {
 400         // The new entry in *merge_cp_p is at a different index than
 401         // the new entry in scratch_cp so we need to map the index values.
 402         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 403       }
 404       (*merge_cp_length_p)++;
 405     } break;
 406 
 407     // this is a double-indirect CP entry so it needs special handling
 408     case JVM_CONSTANT_Fieldref:           // fall through
 409     case JVM_CONSTANT_InterfaceMethodref: // fall through
 410     case JVM_CONSTANT_Methodref:
 411     {
 412       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 413       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
 414                                                           merge_cp_p, merge_cp_length_p, THREAD);
 415 
 416       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 417       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
 418                                                           merge_cp_p, merge_cp_length_p, THREAD);
 419 
 420       const char *entry_name = NULL;
 421       switch (scratch_cp->tag_at(scratch_i).value()) {
 422       case JVM_CONSTANT_Fieldref:
 423         entry_name = "Fieldref";
 424         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 425           new_name_and_type_ref_i);
 426         break;
 427       case JVM_CONSTANT_InterfaceMethodref:
 428         entry_name = "IFMethodref";
 429         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 430           new_klass_ref_i, new_name_and_type_ref_i);
 431         break;
 432       case JVM_CONSTANT_Methodref:
 433         entry_name = "Methodref";
 434         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 435           new_name_and_type_ref_i);
 436         break;
 437       default:
 438         guarantee(false, "bad switch");
 439         break;
 440       }
 441 
 442       if (klass_ref_i != new_klass_ref_i) {
 443         log_trace(redefine, class, constantpool)
 444           ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
 445       }
 446       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 447         log_trace(redefine, class, constantpool)
 448           ("%s entry@%d name_and_type_index changed: %d to %d",
 449            entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
 450       }
 451 
 452       if (scratch_i != *merge_cp_length_p) {
 453         // The new entry in *merge_cp_p is at a different index than
 454         // the new entry in scratch_cp so we need to map the index values.
 455         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 456       }
 457       (*merge_cp_length_p)++;
 458     } break;
 459 
 460     // this is an indirect CP entry so it needs special handling
 461     case JVM_CONSTANT_MethodType:
 462     {
 463       int ref_i = scratch_cp->method_type_index_at(scratch_i);
 464       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 465                                                     merge_cp_length_p, THREAD);
 466       if (new_ref_i != ref_i) {
 467         log_trace(redefine, class, constantpool)
 468           ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
 469       }
 470       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
 471       if (scratch_i != *merge_cp_length_p) {
 472         // The new entry in *merge_cp_p is at a different index than
 473         // the new entry in scratch_cp so we need to map the index values.
 474         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 475       }
 476       (*merge_cp_length_p)++;
 477     } break;
 478 
 479     // this is an indirect CP entry so it needs special handling
 480     case JVM_CONSTANT_MethodHandle:
 481     {
 482       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
 483       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
 484       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 485                                                     merge_cp_length_p, THREAD);
 486       if (new_ref_i != ref_i) {
 487         log_trace(redefine, class, constantpool)
 488           ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
 489       }
 490       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
 491       if (scratch_i != *merge_cp_length_p) {
 492         // The new entry in *merge_cp_p is at a different index than
 493         // the new entry in scratch_cp so we need to map the index values.
 494         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 495       }
 496       (*merge_cp_length_p)++;
 497     } break;
 498 
 499     // this is an indirect CP entry so it needs special handling
 500     case JVM_CONSTANT_InvokeDynamic:
 501     {
 502       // Index of the bootstrap specifier in the operands array
 503       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
 504       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
 505                                             merge_cp_length_p, THREAD);
 506       // The bootstrap method NameAndType_info index
 507       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
 508       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 509                                                     merge_cp_length_p, THREAD);
 510       if (new_bs_i != old_bs_i) {
 511         log_trace(redefine, class, constantpool)
 512           ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
 513            *merge_cp_length_p, old_bs_i, new_bs_i);
 514       }
 515       if (new_ref_i != old_ref_i) {
 516         log_trace(redefine, class, constantpool)
 517           ("InvokeDynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
 518       }
 519 
 520       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
 521       if (scratch_i != *merge_cp_length_p) {
 522         // The new entry in *merge_cp_p is at a different index than
 523         // the new entry in scratch_cp so we need to map the index values.
 524         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 525       }
 526       (*merge_cp_length_p)++;
 527     } break;
 528 
 529     // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
 530     // ClassIndex
 531     case JVM_CONSTANT_ClassIndex: // fall through
 532 
 533     // Invalid is used as the tag for the second constant pool entry
 534     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 535     // not be seen by itself.
 536     case JVM_CONSTANT_Invalid: // fall through
 537 
 538     // At this stage, String could be here, but not StringIndex
 539     case JVM_CONSTANT_StringIndex: // fall through
 540 
 541     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 542     // here
 543     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 544 
 545     default:
 546     {
 547       // leave a breadcrumb
 548       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 549       ShouldNotReachHere();
 550     } break;
 551   } // end switch tag value
 552 } // end append_entry()
 553 
 554 
 555 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
 556       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 557 
 558   int new_ref_i = ref_i;
 559   bool match = (ref_i < *merge_cp_length_p) &&
 560                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
 561 
 562   if (!match) {
 563     // forward reference in *merge_cp_p or not a direct match
 564     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
 565     if (found_i != 0) {
 566       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
 567       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
 568       new_ref_i = found_i;
 569       map_index(scratch_cp, ref_i, found_i);
 570     } else {
 571       // no match found so we have to append this entry to *merge_cp_p
 572       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
 573       // The above call to append_entry() can only append one entry
 574       // so the post call query of *merge_cp_length_p is only for
 575       // the sake of consistency.
 576       new_ref_i = *merge_cp_length_p - 1;
 577     }
 578   }
 579 
 580   return new_ref_i;
 581 } // end find_or_append_indirect_entry()
 582 
 583 
 584 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
 585 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
 586 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
 587 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
 588        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 589 
 590   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
 591   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 592                                                 merge_cp_length_p, THREAD);
 593   if (new_ref_i != old_ref_i) {
 594     log_trace(redefine, class, constantpool)
 595       ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
 596   }
 597 
 598   Array<u2>* merge_ops = (*merge_cp_p)->operands();
 599   int new_bs_i = _operands_cur_length;
 600   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
 601   // However, the operand_offset_at(0) was set in the extend_operands() call.
 602   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
 603                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
 604   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
 605 
 606   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
 607   merge_ops->at_put(new_base++, new_ref_i);
 608   merge_ops->at_put(new_base++, argc);
 609 
 610   for (int i = 0; i < argc; i++) {
 611     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
 612     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
 613                                                       merge_cp_length_p, THREAD);
 614     merge_ops->at_put(new_base++, new_arg_ref_i);
 615     if (new_arg_ref_i != old_arg_ref_i) {
 616       log_trace(redefine, class, constantpool)
 617         ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
 618          _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
 619     }
 620   }
 621   if (old_bs_i != _operands_cur_length) {
 622     // The bootstrap specifier in *merge_cp_p is at a different index than
 623     // that in scratch_cp so we need to map the index values.
 624     map_operand_index(old_bs_i, new_bs_i);
 625   }
 626   _operands_cur_length++;
 627 } // end append_operand()
 628 
 629 
 630 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
 631       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 632 
 633   int new_bs_i = old_bs_i; // bootstrap specifier index
 634   bool match = (old_bs_i < _operands_cur_length) &&
 635                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
 636 
 637   if (!match) {
 638     // forward reference in *merge_cp_p or not a direct match
 639     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
 640                                                     _operands_cur_length, THREAD);
 641     if (found_i != -1) {
 642       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
 643       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
 644       new_bs_i = found_i;
 645       map_operand_index(old_bs_i, found_i);
 646     } else {
 647       // no match found so we have to append this bootstrap specifier to *merge_cp_p
 648       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
 649       new_bs_i = _operands_cur_length - 1;
 650     }
 651   }
 652   return new_bs_i;
 653 } // end find_or_append_operand()
 654 
 655 
 656 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
 657   if (merge_cp->operands() == NULL) {
 658     return;
 659   }
 660   // Shrink the merge_cp operands
 661   merge_cp->shrink_operands(_operands_cur_length, CHECK);
 662 
 663   if (log_is_enabled(Trace, redefine, class, constantpool)) {
 664     // don't want to loop unless we are tracing
 665     int count = 0;
 666     for (int i = 1; i < _operands_index_map_p->length(); i++) {
 667       int value = _operands_index_map_p->at(i);
 668       if (value != -1) {
 669         log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
 670         count++;
 671       }
 672     }
 673   }
 674   // Clean-up
 675   _operands_index_map_p = NULL;
 676   _operands_cur_length = 0;
 677   _operands_index_map_count = 0;
 678 } // end finalize_operands_merge()
 679 
 680 
 681 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 682              InstanceKlass* the_class,
 683              InstanceKlass* scratch_class) {
 684   int i;
 685 
 686   // Check superclasses, or rather their names, since superclasses themselves can be
 687   // requested to replace.
 688   // Check for NULL superclass first since this might be java.lang.Object
 689   if (the_class->super() != scratch_class->super() &&
 690       (the_class->super() == NULL || scratch_class->super() == NULL ||
 691        the_class->super()->name() !=
 692        scratch_class->super()->name())) {
 693     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 694   }
 695 
 696   // Check if the number, names and order of directly implemented interfaces are the same.
 697   // I think in principle we should just check if the sets of names of directly implemented
 698   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 699   // .java file, also changes in .class file) should not matter. However, comparing sets is
 700   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 701   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 702   // rely on it somewhere.
 703   Array<Klass*>* k_interfaces = the_class->local_interfaces();
 704   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
 705   int n_intfs = k_interfaces->length();
 706   if (n_intfs != k_new_interfaces->length()) {
 707     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 708   }
 709   for (i = 0; i < n_intfs; i++) {
 710     if (k_interfaces->at(i)->name() !=
 711         k_new_interfaces->at(i)->name()) {
 712       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 713     }
 714   }
 715 
 716   // Check whether class is in the error init state.
 717   if (the_class->is_in_error_state()) {
 718     // TBD #5057930: special error code is needed in 1.6
 719     return JVMTI_ERROR_INVALID_CLASS;
 720   }
 721 
 722   // Check whether class modifiers are the same.
 723   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 724   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 725   if (old_flags != new_flags) {
 726     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 727   }
 728 
 729   // Check if the number, names, types and order of fields declared in these classes
 730   // are the same.
 731   JavaFieldStream old_fs(the_class);
 732   JavaFieldStream new_fs(scratch_class);
 733   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 734     // access
 735     old_flags = old_fs.access_flags().as_short();
 736     new_flags = new_fs.access_flags().as_short();
 737     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 738       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 739     }
 740     // offset
 741     if (old_fs.offset() != new_fs.offset()) {
 742       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 743     }
 744     // name and signature
 745     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 746     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 747     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 748     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 749     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 750       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 751     }
 752   }
 753 
 754   // If both streams aren't done then we have a differing number of
 755   // fields.
 756   if (!old_fs.done() || !new_fs.done()) {
 757     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 758   }
 759 
 760   // Do a parallel walk through the old and new methods. Detect
 761   // cases where they match (exist in both), have been added in
 762   // the new methods, or have been deleted (exist only in the
 763   // old methods).  The class file parser places methods in order
 764   // by method name, but does not order overloaded methods by
 765   // signature.  In order to determine what fate befell the methods,
 766   // this code places the overloaded new methods that have matching
 767   // old methods in the same order as the old methods and places
 768   // new overloaded methods at the end of overloaded methods of
 769   // that name. The code for this order normalization is adapted
 770   // from the algorithm used in InstanceKlass::find_method().
 771   // Since we are swapping out of order entries as we find them,
 772   // we only have to search forward through the overloaded methods.
 773   // Methods which are added and have the same name as an existing
 774   // method (but different signature) will be put at the end of
 775   // the methods with that name, and the name mismatch code will
 776   // handle them.
 777   Array<Method*>* k_old_methods(the_class->methods());
 778   Array<Method*>* k_new_methods(scratch_class->methods());
 779   int n_old_methods = k_old_methods->length();
 780   int n_new_methods = k_new_methods->length();
 781   Thread* thread = Thread::current();
 782 
 783   int ni = 0;
 784   int oi = 0;
 785   while (true) {
 786     Method* k_old_method;
 787     Method* k_new_method;
 788     enum { matched, added, deleted, undetermined } method_was = undetermined;
 789 
 790     if (oi >= n_old_methods) {
 791       if (ni >= n_new_methods) {
 792         break; // we've looked at everything, done
 793       }
 794       // New method at the end
 795       k_new_method = k_new_methods->at(ni);
 796       method_was = added;
 797     } else if (ni >= n_new_methods) {
 798       // Old method, at the end, is deleted
 799       k_old_method = k_old_methods->at(oi);
 800       method_was = deleted;
 801     } else {
 802       // There are more methods in both the old and new lists
 803       k_old_method = k_old_methods->at(oi);
 804       k_new_method = k_new_methods->at(ni);
 805       if (k_old_method->name() != k_new_method->name()) {
 806         // Methods are sorted by method name, so a mismatch means added
 807         // or deleted
 808         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 809           method_was = added;
 810         } else {
 811           method_was = deleted;
 812         }
 813       } else if (k_old_method->signature() == k_new_method->signature()) {
 814         // Both the name and signature match
 815         method_was = matched;
 816       } else {
 817         // The name matches, but the signature doesn't, which means we have to
 818         // search forward through the new overloaded methods.
 819         int nj;  // outside the loop for post-loop check
 820         for (nj = ni + 1; nj < n_new_methods; nj++) {
 821           Method* m = k_new_methods->at(nj);
 822           if (k_old_method->name() != m->name()) {
 823             // reached another method name so no more overloaded methods
 824             method_was = deleted;
 825             break;
 826           }
 827           if (k_old_method->signature() == m->signature()) {
 828             // found a match so swap the methods
 829             k_new_methods->at_put(ni, m);
 830             k_new_methods->at_put(nj, k_new_method);
 831             k_new_method = m;
 832             method_was = matched;
 833             break;
 834           }
 835         }
 836 
 837         if (nj >= n_new_methods) {
 838           // reached the end without a match; so method was deleted
 839           method_was = deleted;
 840         }
 841       }
 842     }
 843 
 844     switch (method_was) {
 845     case matched:
 846       // methods match, be sure modifiers do too
 847       old_flags = (jushort) k_old_method->access_flags().get_flags();
 848       new_flags = (jushort) k_new_method->access_flags().get_flags();
 849       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 850         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 851       }
 852       {
 853         u2 new_num = k_new_method->method_idnum();
 854         u2 old_num = k_old_method->method_idnum();
 855         if (new_num != old_num) {
 856           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
 857           if (idnum_owner != NULL) {
 858             // There is already a method assigned this idnum -- switch them
 859             // Take current and original idnum from the new_method
 860             idnum_owner->set_method_idnum(new_num);
 861             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 862           }
 863           // Take current and original idnum from the old_method
 864           k_new_method->set_method_idnum(old_num);
 865           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
 866           if (thread->has_pending_exception()) {
 867             return JVMTI_ERROR_OUT_OF_MEMORY;
 868           }
 869         }
 870       }
 871       log_trace(redefine, class, normalize)
 872         ("Method matched: new: %s [%d] == old: %s [%d]",
 873          k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
 874       // advance to next pair of methods
 875       ++oi;
 876       ++ni;
 877       break;
 878     case added:
 879       // method added, see if it is OK
 880       new_flags = (jushort) k_new_method->access_flags().get_flags();
 881       if ((new_flags & JVM_ACC_PRIVATE) == 0
 882            // hack: private should be treated as final, but alas
 883           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 884          ) {
 885         // new methods must be private
 886         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 887       }
 888       {
 889         u2 num = the_class->next_method_idnum();
 890         if (num == ConstMethod::UNSET_IDNUM) {
 891           // cannot add any more methods
 892           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 893         }
 894         u2 new_num = k_new_method->method_idnum();
 895         Method* idnum_owner = scratch_class->method_with_idnum(num);
 896         if (idnum_owner != NULL) {
 897           // There is already a method assigned this idnum -- switch them
 898           // Take current and original idnum from the new_method
 899           idnum_owner->set_method_idnum(new_num);
 900           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 901         }
 902         k_new_method->set_method_idnum(num);
 903         k_new_method->set_orig_method_idnum(num);
 904         if (thread->has_pending_exception()) {
 905           return JVMTI_ERROR_OUT_OF_MEMORY;
 906         }
 907       }
 908       log_trace(redefine, class, normalize)
 909         ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
 910       ++ni; // advance to next new method
 911       break;
 912     case deleted:
 913       // method deleted, see if it is OK
 914       old_flags = (jushort) k_old_method->access_flags().get_flags();
 915       if ((old_flags & JVM_ACC_PRIVATE) == 0
 916            // hack: private should be treated as final, but alas
 917           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 918          ) {
 919         // deleted methods must be private
 920         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 921       }
 922       log_trace(redefine, class, normalize)
 923         ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
 924       ++oi; // advance to next old method
 925       break;
 926     default:
 927       ShouldNotReachHere();
 928     }
 929   }
 930 
 931   return JVMTI_ERROR_NONE;
 932 }
 933 
 934 
 935 // Find new constant pool index value for old constant pool index value
 936 // by seaching the index map. Returns zero (0) if there is no mapped
 937 // value for the old constant pool index.
 938 int VM_RedefineClasses::find_new_index(int old_index) {
 939   if (_index_map_count == 0) {
 940     // map is empty so nothing can be found
 941     return 0;
 942   }
 943 
 944   if (old_index < 1 || old_index >= _index_map_p->length()) {
 945     // The old_index is out of range so it is not mapped. This should
 946     // not happen in regular constant pool merging use, but it can
 947     // happen if a corrupt annotation is processed.
 948     return 0;
 949   }
 950 
 951   int value = _index_map_p->at(old_index);
 952   if (value == -1) {
 953     // the old_index is not mapped
 954     return 0;
 955   }
 956 
 957   return value;
 958 } // end find_new_index()
 959 
 960 
 961 // Find new bootstrap specifier index value for old bootstrap specifier index
 962 // value by seaching the index map. Returns unused index (-1) if there is
 963 // no mapped value for the old bootstrap specifier index.
 964 int VM_RedefineClasses::find_new_operand_index(int old_index) {
 965   if (_operands_index_map_count == 0) {
 966     // map is empty so nothing can be found
 967     return -1;
 968   }
 969 
 970   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
 971     // The old_index is out of range so it is not mapped.
 972     // This should not happen in regular constant pool merging use.
 973     return -1;
 974   }
 975 
 976   int value = _operands_index_map_p->at(old_index);
 977   if (value == -1) {
 978     // the old_index is not mapped
 979     return -1;
 980   }
 981 
 982   return value;
 983 } // end find_new_operand_index()
 984 
 985 
 986 // Returns true if the current mismatch is due to a resolved/unresolved
 987 // class pair. Otherwise, returns false.
 988 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
 989        int index1, const constantPoolHandle& cp2, int index2) {
 990 
 991   jbyte t1 = cp1->tag_at(index1).value();
 992   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 993     return false;  // wrong entry type; not our special case
 994   }
 995 
 996   jbyte t2 = cp2->tag_at(index2).value();
 997   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 998     return false;  // wrong entry type; not our special case
 999   }
1000 
1001   if (t1 == t2) {
1002     return false;  // not a mismatch; not our special case
1003   }
1004 
1005   char *s1 = cp1->klass_name_at(index1)->as_C_string();
1006   char *s2 = cp2->klass_name_at(index2)->as_C_string();
1007   if (strcmp(s1, s2) != 0) {
1008     return false;  // strings don't match; not our special case
1009   }
1010 
1011   return true;  // made it through the gauntlet; this is our special case
1012 } // end is_unresolved_class_mismatch()
1013 
1014 
1015 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1016 
1017   // For consistency allocate memory using os::malloc wrapper.
1018   _scratch_classes = (InstanceKlass**)
1019     os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1020   if (_scratch_classes == NULL) {
1021     return JVMTI_ERROR_OUT_OF_MEMORY;
1022   }
1023   // Zero initialize the _scratch_classes array.
1024   for (int i = 0; i < _class_count; i++) {
1025     _scratch_classes[i] = NULL;
1026   }
1027 
1028   ResourceMark rm(THREAD);
1029 
1030   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1031   // state can only be NULL if the current thread is exiting which
1032   // should not happen since we're trying to do a RedefineClasses
1033   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1034   for (int i = 0; i < _class_count; i++) {
1035     // Create HandleMark so that any handles created while loading new class
1036     // versions are deleted. Constant pools are deallocated while merging
1037     // constant pools
1038     HandleMark hm(THREAD);
1039     InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1040     Symbol*  the_class_sym = the_class->name();
1041 
1042     log_debug(redefine, class, load)
1043       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1044        the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1045 
1046     ClassFileStream st((u1*)_class_defs[i].class_bytes,
1047                        _class_defs[i].class_byte_count,
1048                        "__VM_RedefineClasses__",
1049                        ClassFileStream::verify);
1050 
1051     // Parse the stream.
1052     Handle the_class_loader(THREAD, the_class->class_loader());
1053     Handle protection_domain(THREAD, the_class->protection_domain());
1054     // Set redefined class handle in JvmtiThreadState class.
1055     // This redefined class is sent to agent event handler for class file
1056     // load hook event.
1057     state->set_class_being_redefined(the_class, _class_load_kind);
1058 
1059     InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1060                                                       the_class_sym,
1061                                                       the_class_loader,
1062                                                       protection_domain,
1063                                                       &st,
1064                                                       THREAD);
1065     // Clear class_being_redefined just to be sure.
1066     state->clear_class_being_redefined();
1067 
1068     // TODO: if this is retransform, and nothing changed we can skip it
1069 
1070     // Need to clean up allocated InstanceKlass if there's an error so assign
1071     // the result here. Caller deallocates all the scratch classes in case of
1072     // an error.
1073     _scratch_classes[i] = scratch_class;
1074 
1075     if (HAS_PENDING_EXCEPTION) {
1076       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1077       log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1078       CLEAR_PENDING_EXCEPTION;
1079 
1080       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1081         return JVMTI_ERROR_UNSUPPORTED_VERSION;
1082       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1083         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1084       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1085         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1086       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1087         // The message will be "XXX (wrong name: YYY)"
1088         return JVMTI_ERROR_NAMES_DONT_MATCH;
1089       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1090         return JVMTI_ERROR_OUT_OF_MEMORY;
1091       } else {  // Just in case more exceptions can be thrown..
1092         return JVMTI_ERROR_FAILS_VERIFICATION;
1093       }
1094     }
1095 
1096     // Ensure class is linked before redefine
1097     if (!the_class->is_linked()) {
1098       the_class->link_class(THREAD);
1099       if (HAS_PENDING_EXCEPTION) {
1100         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1101         log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1102         CLEAR_PENDING_EXCEPTION;
1103         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1104           return JVMTI_ERROR_OUT_OF_MEMORY;
1105         } else {
1106           return JVMTI_ERROR_INTERNAL;
1107         }
1108       }
1109     }
1110 
1111     // Do the validity checks in compare_and_normalize_class_versions()
1112     // before verifying the byte codes. By doing these checks first, we
1113     // limit the number of functions that require redirection from
1114     // the_class to scratch_class. In particular, we don't have to
1115     // modify JNI GetSuperclass() and thus won't change its performance.
1116     jvmtiError res = compare_and_normalize_class_versions(the_class,
1117                        scratch_class);
1118     if (res != JVMTI_ERROR_NONE) {
1119       return res;
1120     }
1121 
1122     // verify what the caller passed us
1123     {
1124       // The bug 6214132 caused the verification to fail.
1125       // Information about the_class and scratch_class is temporarily
1126       // recorded into jvmtiThreadState. This data is used to redirect
1127       // the_class to scratch_class in the JVM_* functions called by the
1128       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1129       // description.
1130       RedefineVerifyMark rvm(the_class, scratch_class, state);
1131       Verifier::verify(
1132         scratch_class, Verifier::ThrowException, true, THREAD);
1133     }
1134 
1135     if (HAS_PENDING_EXCEPTION) {
1136       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1137       log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1138       CLEAR_PENDING_EXCEPTION;
1139       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1140         return JVMTI_ERROR_OUT_OF_MEMORY;
1141       } else {
1142         // tell the caller the bytecodes are bad
1143         return JVMTI_ERROR_FAILS_VERIFICATION;
1144       }
1145     }
1146 
1147     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1148     if (HAS_PENDING_EXCEPTION) {
1149       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1150       log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1151       CLEAR_PENDING_EXCEPTION;
1152       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1153         return JVMTI_ERROR_OUT_OF_MEMORY;
1154       } else {
1155         return JVMTI_ERROR_INTERNAL;
1156       }
1157     }
1158 
1159     if (VerifyMergedCPBytecodes) {
1160       // verify what we have done during constant pool merging
1161       {
1162         RedefineVerifyMark rvm(the_class, scratch_class, state);
1163         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1164       }
1165 
1166       if (HAS_PENDING_EXCEPTION) {
1167         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1168         log_info(redefine, class, load, exceptions)
1169           ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1170         CLEAR_PENDING_EXCEPTION;
1171         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1172           return JVMTI_ERROR_OUT_OF_MEMORY;
1173         } else {
1174           // tell the caller that constant pool merging screwed up
1175           return JVMTI_ERROR_INTERNAL;
1176         }
1177       }
1178     }
1179 
1180     Rewriter::rewrite(scratch_class, THREAD);
1181     if (!HAS_PENDING_EXCEPTION) {
1182       scratch_class->link_methods(THREAD);
1183     }
1184     if (HAS_PENDING_EXCEPTION) {
1185       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1186       log_info(redefine, class, load, exceptions)
1187         ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1188       CLEAR_PENDING_EXCEPTION;
1189       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1190         return JVMTI_ERROR_OUT_OF_MEMORY;
1191       } else {
1192         return JVMTI_ERROR_INTERNAL;
1193       }
1194     }
1195 
1196     log_debug(redefine, class, load)
1197       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1198   }
1199 
1200   return JVMTI_ERROR_NONE;
1201 }
1202 
1203 
1204 // Map old_index to new_index as needed. scratch_cp is only needed
1205 // for log calls.
1206 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1207        int old_index, int new_index) {
1208   if (find_new_index(old_index) != 0) {
1209     // old_index is already mapped
1210     return;
1211   }
1212 
1213   if (old_index == new_index) {
1214     // no mapping is needed
1215     return;
1216   }
1217 
1218   _index_map_p->at_put(old_index, new_index);
1219   _index_map_count++;
1220 
1221   log_trace(redefine, class, constantpool)
1222     ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1223 } // end map_index()
1224 
1225 
1226 // Map old_index to new_index as needed.
1227 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1228   if (find_new_operand_index(old_index) != -1) {
1229     // old_index is already mapped
1230     return;
1231   }
1232 
1233   if (old_index == new_index) {
1234     // no mapping is needed
1235     return;
1236   }
1237 
1238   _operands_index_map_p->at_put(old_index, new_index);
1239   _operands_index_map_count++;
1240 
1241   log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1242 } // end map_index()
1243 
1244 
1245 // Merge old_cp and scratch_cp and return the results of the merge via
1246 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1247 // merge_cp_length_p. The entries in old_cp occupy the same locations
1248 // in *merge_cp_p. Also creates a map of indices from entries in
1249 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1250 // entries are only created for entries in scratch_cp that occupy a
1251 // different location in *merged_cp_p.
1252 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1253        const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1254        int *merge_cp_length_p, TRAPS) {
1255 
1256   if (merge_cp_p == NULL) {
1257     assert(false, "caller must provide scratch constantPool");
1258     return false; // robustness
1259   }
1260   if (merge_cp_length_p == NULL) {
1261     assert(false, "caller must provide scratch CP length");
1262     return false; // robustness
1263   }
1264   // Worst case we need old_cp->length() + scratch_cp()->length(),
1265   // but the caller might be smart so make sure we have at least
1266   // the minimum.
1267   if ((*merge_cp_p)->length() < old_cp->length()) {
1268     assert(false, "merge area too small");
1269     return false; // robustness
1270   }
1271 
1272   log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1273 
1274   {
1275     // Pass 0:
1276     // The old_cp is copied to *merge_cp_p; this means that any code
1277     // using old_cp does not have to change. This work looks like a
1278     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1279     // handle one special case:
1280     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1281     // This will make verification happy.
1282 
1283     int old_i;  // index into old_cp
1284 
1285     // index zero (0) is not used in constantPools
1286     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1287       // leave debugging crumb
1288       jbyte old_tag = old_cp->tag_at(old_i).value();
1289       switch (old_tag) {
1290       case JVM_CONSTANT_Class:
1291       case JVM_CONSTANT_UnresolvedClass:
1292         // revert the copy to JVM_CONSTANT_UnresolvedClass
1293         // May be resolving while calling this so do the same for
1294         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1295         (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1296           old_cp->klass_name_index_at(old_i));
1297         break;
1298 
1299       case JVM_CONSTANT_Double:
1300       case JVM_CONSTANT_Long:
1301         // just copy the entry to *merge_cp_p, but double and long take
1302         // two constant pool entries
1303         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1304         old_i++;
1305         break;
1306 
1307       default:
1308         // just copy the entry to *merge_cp_p
1309         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1310         break;
1311       }
1312     } // end for each old_cp entry
1313 
1314     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1315     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1316 
1317     // We don't need to sanity check that *merge_cp_length_p is within
1318     // *merge_cp_p bounds since we have the minimum on-entry check above.
1319     (*merge_cp_length_p) = old_i;
1320   }
1321 
1322   // merge_cp_len should be the same as old_cp->length() at this point
1323   // so this trace message is really a "warm-and-breathing" message.
1324   log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1325 
1326   int scratch_i;  // index into scratch_cp
1327   {
1328     // Pass 1a:
1329     // Compare scratch_cp entries to the old_cp entries that we have
1330     // already copied to *merge_cp_p. In this pass, we are eliminating
1331     // exact duplicates (matching entry at same index) so we only
1332     // compare entries in the common indice range.
1333     int increment = 1;
1334     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1335     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1336       switch (scratch_cp->tag_at(scratch_i).value()) {
1337       case JVM_CONSTANT_Double:
1338       case JVM_CONSTANT_Long:
1339         // double and long take two constant pool entries
1340         increment = 2;
1341         break;
1342 
1343       default:
1344         increment = 1;
1345         break;
1346       }
1347 
1348       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1349         scratch_i, CHECK_0);
1350       if (match) {
1351         // found a match at the same index so nothing more to do
1352         continue;
1353       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1354                                               *merge_cp_p, scratch_i)) {
1355         // The mismatch in compare_entry_to() above is because of a
1356         // resolved versus unresolved class entry at the same index
1357         // with the same string value. Since Pass 0 reverted any
1358         // class entries to unresolved class entries in *merge_cp_p,
1359         // we go with the unresolved class entry.
1360         continue;
1361       }
1362 
1363       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1364         CHECK_0);
1365       if (found_i != 0) {
1366         guarantee(found_i != scratch_i,
1367           "compare_entry_to() and find_matching_entry() do not agree");
1368 
1369         // Found a matching entry somewhere else in *merge_cp_p so
1370         // just need a mapping entry.
1371         map_index(scratch_cp, scratch_i, found_i);
1372         continue;
1373       }
1374 
1375       // The find_matching_entry() call above could fail to find a match
1376       // due to a resolved versus unresolved class or string entry situation
1377       // like we solved above with the is_unresolved_*_mismatch() calls.
1378       // However, we would have to call is_unresolved_*_mismatch() over
1379       // all of *merge_cp_p (potentially) and that doesn't seem to be
1380       // worth the time.
1381 
1382       // No match found so we have to append this entry and any unique
1383       // referenced entries to *merge_cp_p.
1384       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1385         CHECK_0);
1386     }
1387   }
1388 
1389   log_debug(redefine, class, constantpool)
1390     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1391      *merge_cp_length_p, scratch_i, _index_map_count);
1392 
1393   if (scratch_i < scratch_cp->length()) {
1394     // Pass 1b:
1395     // old_cp is smaller than scratch_cp so there are entries in
1396     // scratch_cp that we have not yet processed. We take care of
1397     // those now.
1398     int increment = 1;
1399     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1400       switch (scratch_cp->tag_at(scratch_i).value()) {
1401       case JVM_CONSTANT_Double:
1402       case JVM_CONSTANT_Long:
1403         // double and long take two constant pool entries
1404         increment = 2;
1405         break;
1406 
1407       default:
1408         increment = 1;
1409         break;
1410       }
1411 
1412       int found_i =
1413         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1414       if (found_i != 0) {
1415         // Found a matching entry somewhere else in *merge_cp_p so
1416         // just need a mapping entry.
1417         map_index(scratch_cp, scratch_i, found_i);
1418         continue;
1419       }
1420 
1421       // No match found so we have to append this entry and any unique
1422       // referenced entries to *merge_cp_p.
1423       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1424         CHECK_0);
1425     }
1426 
1427     log_debug(redefine, class, constantpool)
1428       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1429        *merge_cp_length_p, scratch_i, _index_map_count);
1430   }
1431   finalize_operands_merge(*merge_cp_p, THREAD);
1432 
1433   return true;
1434 } // end merge_constant_pools()
1435 
1436 
1437 // Scoped object to clean up the constant pool(s) created for merging
1438 class MergeCPCleaner {
1439   ClassLoaderData*   _loader_data;
1440   ConstantPool*      _cp;
1441   ConstantPool*      _scratch_cp;
1442  public:
1443   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1444                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1445   ~MergeCPCleaner() {
1446     _loader_data->add_to_deallocate_list(_cp);
1447     if (_scratch_cp != NULL) {
1448       _loader_data->add_to_deallocate_list(_scratch_cp);
1449     }
1450   }
1451   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1452 };
1453 
1454 // Merge constant pools between the_class and scratch_class and
1455 // potentially rewrite bytecodes in scratch_class to use the merged
1456 // constant pool.
1457 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1458              InstanceKlass* the_class, InstanceKlass* scratch_class,
1459              TRAPS) {
1460   // worst case merged constant pool length is old and new combined
1461   int merge_cp_length = the_class->constants()->length()
1462         + scratch_class->constants()->length();
1463 
1464   // Constant pools are not easily reused so we allocate a new one
1465   // each time.
1466   // merge_cp is created unsafe for concurrent GC processing.  It
1467   // should be marked safe before discarding it. Even though
1468   // garbage,  if it crosses a card boundary, it may be scanned
1469   // in order to find the start of the first complete object on the card.
1470   ClassLoaderData* loader_data = the_class->class_loader_data();
1471   ConstantPool* merge_cp_oop =
1472     ConstantPool::allocate(loader_data,
1473                            merge_cp_length,
1474                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1475   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1476 
1477   HandleMark hm(THREAD);  // make sure handles are cleared before
1478                           // MergeCPCleaner clears out merge_cp_oop
1479   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1480 
1481   // Get constants() from the old class because it could have been rewritten
1482   // while we were at a safepoint allocating a new constant pool.
1483   constantPoolHandle old_cp(THREAD, the_class->constants());
1484   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1485 
1486   // If the length changed, the class was redefined out from under us. Return
1487   // an error.
1488   if (merge_cp_length != the_class->constants()->length()
1489          + scratch_class->constants()->length()) {
1490     return JVMTI_ERROR_INTERNAL;
1491   }
1492 
1493   // Update the version number of the constant pools (may keep scratch_cp)
1494   merge_cp->increment_and_save_version(old_cp->version());
1495   scratch_cp->increment_and_save_version(old_cp->version());
1496 
1497   ResourceMark rm(THREAD);
1498   _index_map_count = 0;
1499   _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1500 
1501   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1502   _operands_index_map_count = 0;
1503   int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1504   _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1505 
1506   // reference to the cp holder is needed for copy_operands()
1507   merge_cp->set_pool_holder(scratch_class);
1508   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1509                   &merge_cp_length, THREAD);
1510   merge_cp->set_pool_holder(NULL);
1511 
1512   if (!result) {
1513     // The merge can fail due to memory allocation failure or due
1514     // to robustness checks.
1515     return JVMTI_ERROR_INTERNAL;
1516   }
1517 
1518   log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1519 
1520   if (_index_map_count == 0) {
1521     // there is nothing to map between the new and merged constant pools
1522 
1523     if (old_cp->length() == scratch_cp->length()) {
1524       // The old and new constant pools are the same length and the
1525       // index map is empty. This means that the three constant pools
1526       // are equivalent (but not the same). Unfortunately, the new
1527       // constant pool has not gone through link resolution nor have
1528       // the new class bytecodes gone through constant pool cache
1529       // rewriting so we can't use the old constant pool with the new
1530       // class.
1531 
1532       // toss the merged constant pool at return
1533     } else if (old_cp->length() < scratch_cp->length()) {
1534       // The old constant pool has fewer entries than the new constant
1535       // pool and the index map is empty. This means the new constant
1536       // pool is a superset of the old constant pool. However, the old
1537       // class bytecodes have already gone through constant pool cache
1538       // rewriting so we can't use the new constant pool with the old
1539       // class.
1540 
1541       // toss the merged constant pool at return
1542     } else {
1543       // The old constant pool has more entries than the new constant
1544       // pool and the index map is empty. This means that both the old
1545       // and merged constant pools are supersets of the new constant
1546       // pool.
1547 
1548       // Replace the new constant pool with a shrunken copy of the
1549       // merged constant pool
1550       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1551                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1552       // The new constant pool replaces scratch_cp so have cleaner clean it up.
1553       // It can't be cleaned up while there are handles to it.
1554       cp_cleaner.add_scratch_cp(scratch_cp());
1555     }
1556   } else {
1557     if (log_is_enabled(Trace, redefine, class, constantpool)) {
1558       // don't want to loop unless we are tracing
1559       int count = 0;
1560       for (int i = 1; i < _index_map_p->length(); i++) {
1561         int value = _index_map_p->at(i);
1562 
1563         if (value != -1) {
1564           log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1565           count++;
1566         }
1567       }
1568     }
1569 
1570     // We have entries mapped between the new and merged constant pools
1571     // so we have to rewrite some constant pool references.
1572     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1573       return JVMTI_ERROR_INTERNAL;
1574     }
1575 
1576     // Replace the new constant pool with a shrunken copy of the
1577     // merged constant pool so now the rewritten bytecodes have
1578     // valid references; the previous new constant pool will get
1579     // GCed.
1580     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1581                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1582     // The new constant pool replaces scratch_cp so have cleaner clean it up.
1583     // It can't be cleaned up while there are handles to it.
1584     cp_cleaner.add_scratch_cp(scratch_cp());
1585   }
1586 
1587   return JVMTI_ERROR_NONE;
1588 } // end merge_cp_and_rewrite()
1589 
1590 
1591 // Rewrite constant pool references in klass scratch_class.
1592 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1593        TRAPS) {
1594 
1595   // rewrite constant pool references in the methods:
1596   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1597     // propagate failure back to caller
1598     return false;
1599   }
1600 
1601   // rewrite constant pool references in the class_annotations:
1602   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1603     // propagate failure back to caller
1604     return false;
1605   }
1606 
1607   // rewrite constant pool references in the fields_annotations:
1608   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1609     // propagate failure back to caller
1610     return false;
1611   }
1612 
1613   // rewrite constant pool references in the methods_annotations:
1614   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1615     // propagate failure back to caller
1616     return false;
1617   }
1618 
1619   // rewrite constant pool references in the methods_parameter_annotations:
1620   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1621          THREAD)) {
1622     // propagate failure back to caller
1623     return false;
1624   }
1625 
1626   // rewrite constant pool references in the methods_default_annotations:
1627   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1628          THREAD)) {
1629     // propagate failure back to caller
1630     return false;
1631   }
1632 
1633   // rewrite constant pool references in the class_type_annotations:
1634   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1635     // propagate failure back to caller
1636     return false;
1637   }
1638 
1639   // rewrite constant pool references in the fields_type_annotations:
1640   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1641     // propagate failure back to caller
1642     return false;
1643   }
1644 
1645   // rewrite constant pool references in the methods_type_annotations:
1646   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1647     // propagate failure back to caller
1648     return false;
1649   }
1650 
1651   // There can be type annotations in the Code part of a method_info attribute.
1652   // These annotations are not accessible, even by reflection.
1653   // Currently they are not even parsed by the ClassFileParser.
1654   // If runtime access is added they will also need to be rewritten.
1655 
1656   // rewrite source file name index:
1657   u2 source_file_name_idx = scratch_class->source_file_name_index();
1658   if (source_file_name_idx != 0) {
1659     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1660     if (new_source_file_name_idx != 0) {
1661       scratch_class->set_source_file_name_index(new_source_file_name_idx);
1662     }
1663   }
1664 
1665   // rewrite class generic signature index:
1666   u2 generic_signature_index = scratch_class->generic_signature_index();
1667   if (generic_signature_index != 0) {
1668     u2 new_generic_signature_index = find_new_index(generic_signature_index);
1669     if (new_generic_signature_index != 0) {
1670       scratch_class->set_generic_signature_index(new_generic_signature_index);
1671     }
1672   }
1673 
1674   return true;
1675 } // end rewrite_cp_refs()
1676 
1677 // Rewrite constant pool references in the methods.
1678 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1679        InstanceKlass* scratch_class, TRAPS) {
1680 
1681   Array<Method*>* methods = scratch_class->methods();
1682 
1683   if (methods == NULL || methods->length() == 0) {
1684     // no methods so nothing to do
1685     return true;
1686   }
1687 
1688   // rewrite constant pool references in the methods:
1689   for (int i = methods->length() - 1; i >= 0; i--) {
1690     methodHandle method(THREAD, methods->at(i));
1691     methodHandle new_method;
1692     rewrite_cp_refs_in_method(method, &new_method, THREAD);
1693     if (!new_method.is_null()) {
1694       // the method has been replaced so save the new method version
1695       // even in the case of an exception.  original method is on the
1696       // deallocation list.
1697       methods->at_put(i, new_method());
1698     }
1699     if (HAS_PENDING_EXCEPTION) {
1700       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1701       log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1702       // Need to clear pending exception here as the super caller sets
1703       // the JVMTI_ERROR_INTERNAL if the returned value is false.
1704       CLEAR_PENDING_EXCEPTION;
1705       return false;
1706     }
1707   }
1708 
1709   return true;
1710 }
1711 
1712 
1713 // Rewrite constant pool references in the specific method. This code
1714 // was adapted from Rewriter::rewrite_method().
1715 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1716        methodHandle *new_method_p, TRAPS) {
1717 
1718   *new_method_p = methodHandle();  // default is no new method
1719 
1720   // We cache a pointer to the bytecodes here in code_base. If GC
1721   // moves the Method*, then the bytecodes will also move which
1722   // will likely cause a crash. We create a NoSafepointVerifier
1723   // object to detect whether we pass a possible safepoint in this
1724   // code block.
1725   NoSafepointVerifier nsv;
1726 
1727   // Bytecodes and their length
1728   address code_base = method->code_base();
1729   int code_length = method->code_size();
1730 
1731   int bc_length;
1732   for (int bci = 0; bci < code_length; bci += bc_length) {
1733     address bcp = code_base + bci;
1734     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1735 
1736     bc_length = Bytecodes::length_for(c);
1737     if (bc_length == 0) {
1738       // More complicated bytecodes report a length of zero so
1739       // we have to try again a slightly different way.
1740       bc_length = Bytecodes::length_at(method(), bcp);
1741     }
1742 
1743     assert(bc_length != 0, "impossible bytecode length");
1744 
1745     switch (c) {
1746       case Bytecodes::_ldc:
1747       {
1748         int cp_index = *(bcp + 1);
1749         int new_index = find_new_index(cp_index);
1750 
1751         if (StressLdcRewrite && new_index == 0) {
1752           // If we are stressing ldc -> ldc_w rewriting, then we
1753           // always need a new_index value.
1754           new_index = cp_index;
1755         }
1756         if (new_index != 0) {
1757           // the original index is mapped so we have more work to do
1758           if (!StressLdcRewrite && new_index <= max_jubyte) {
1759             // The new value can still use ldc instead of ldc_w
1760             // unless we are trying to stress ldc -> ldc_w rewriting
1761             log_trace(redefine, class, constantpool)
1762               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1763             *(bcp + 1) = new_index;
1764           } else {
1765             log_trace(redefine, class, constantpool)
1766               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1767             // the new value needs ldc_w instead of ldc
1768             u_char inst_buffer[4]; // max instruction size is 4 bytes
1769             bcp = (address)inst_buffer;
1770             // construct new instruction sequence
1771             *bcp = Bytecodes::_ldc_w;
1772             bcp++;
1773             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1774             // See comment below for difference between put_Java_u2()
1775             // and put_native_u2().
1776             Bytes::put_Java_u2(bcp, new_index);
1777 
1778             Relocator rc(method, NULL /* no RelocatorListener needed */);
1779             methodHandle m;
1780             {
1781               PauseNoSafepointVerifier pnsv(&nsv);
1782 
1783               // ldc is 2 bytes and ldc_w is 3 bytes
1784               m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1785             }
1786 
1787             // return the new method so that the caller can update
1788             // the containing class
1789             *new_method_p = method = m;
1790             // switch our bytecode processing loop from the old method
1791             // to the new method
1792             code_base = method->code_base();
1793             code_length = method->code_size();
1794             bcp = code_base + bci;
1795             c = (Bytecodes::Code)(*bcp);
1796             bc_length = Bytecodes::length_for(c);
1797             assert(bc_length != 0, "sanity check");
1798           } // end we need ldc_w instead of ldc
1799         } // end if there is a mapped index
1800       } break;
1801 
1802       // these bytecodes have a two-byte constant pool index
1803       case Bytecodes::_anewarray      : // fall through
1804       case Bytecodes::_checkcast      : // fall through
1805       case Bytecodes::_getfield       : // fall through
1806       case Bytecodes::_getstatic      : // fall through
1807       case Bytecodes::_instanceof     : // fall through
1808       case Bytecodes::_invokedynamic  : // fall through
1809       case Bytecodes::_invokeinterface: // fall through
1810       case Bytecodes::_invokespecial  : // fall through
1811       case Bytecodes::_invokestatic   : // fall through
1812       case Bytecodes::_invokevirtual  : // fall through
1813       case Bytecodes::_ldc_w          : // fall through
1814       case Bytecodes::_ldc2_w         : // fall through
1815       case Bytecodes::_multianewarray : // fall through
1816       case Bytecodes::_new            : // fall through
1817       case Bytecodes::_putfield       : // fall through
1818       case Bytecodes::_putstatic      :
1819       {
1820         address p = bcp + 1;
1821         int cp_index = Bytes::get_Java_u2(p);
1822         int new_index = find_new_index(cp_index);
1823         if (new_index != 0) {
1824           // the original index is mapped so update w/ new value
1825           log_trace(redefine, class, constantpool)
1826             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
1827           // Rewriter::rewrite_method() uses put_native_u2() in this
1828           // situation because it is reusing the constant pool index
1829           // location for a native index into the ConstantPoolCache.
1830           // Since we are updating the constant pool index prior to
1831           // verification and ConstantPoolCache initialization, we
1832           // need to keep the new index in Java byte order.
1833           Bytes::put_Java_u2(p, new_index);
1834         }
1835       } break;
1836       default:
1837         break;
1838     }
1839   } // end for each bytecode
1840 
1841   // We also need to rewrite the parameter name indexes, if there is
1842   // method parameter data present
1843   if(method->has_method_parameters()) {
1844     const int len = method->method_parameters_length();
1845     MethodParametersElement* elem = method->method_parameters_start();
1846 
1847     for (int i = 0; i < len; i++) {
1848       const u2 cp_index = elem[i].name_cp_index;
1849       const u2 new_cp_index = find_new_index(cp_index);
1850       if (new_cp_index != 0) {
1851         elem[i].name_cp_index = new_cp_index;
1852       }
1853     }
1854   }
1855 } // end rewrite_cp_refs_in_method()
1856 
1857 
1858 // Rewrite constant pool references in the class_annotations field.
1859 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1860        InstanceKlass* scratch_class, TRAPS) {
1861 
1862   AnnotationArray* class_annotations = scratch_class->class_annotations();
1863   if (class_annotations == NULL || class_annotations->length() == 0) {
1864     // no class_annotations so nothing to do
1865     return true;
1866   }
1867 
1868   log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
1869 
1870   int byte_i = 0;  // byte index into class_annotations
1871   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1872            THREAD);
1873 }
1874 
1875 
1876 // Rewrite constant pool references in an annotations typeArray. This
1877 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1878 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1879 //
1880 // annotations_typeArray {
1881 //   u2 num_annotations;
1882 //   annotation annotations[num_annotations];
1883 // }
1884 //
1885 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1886        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1887 
1888   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1889     // not enough room for num_annotations field
1890     log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
1891     return false;
1892   }
1893 
1894   u2 num_annotations = Bytes::get_Java_u2((address)
1895                          annotations_typeArray->adr_at(byte_i_ref));
1896   byte_i_ref += 2;
1897 
1898   log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
1899 
1900   int calc_num_annotations = 0;
1901   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1902     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1903            byte_i_ref, THREAD)) {
1904       log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
1905       // propagate failure back to caller
1906       return false;
1907     }
1908   }
1909   assert(num_annotations == calc_num_annotations, "sanity check");
1910 
1911   return true;
1912 } // end rewrite_cp_refs_in_annotations_typeArray()
1913 
1914 
1915 // Rewrite constant pool references in the annotation struct portion of
1916 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1917 // the 2nd-edition of the VM spec:
1918 //
1919 // struct annotation {
1920 //   u2 type_index;
1921 //   u2 num_element_value_pairs;
1922 //   {
1923 //     u2 element_name_index;
1924 //     element_value value;
1925 //   } element_value_pairs[num_element_value_pairs];
1926 // }
1927 //
1928 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1929        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1930   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1931     // not enough room for smallest annotation_struct
1932     log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
1933     return false;
1934   }
1935 
1936   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1937                     byte_i_ref, "type_index", THREAD);
1938 
1939   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1940                                  annotations_typeArray->adr_at(byte_i_ref));
1941   byte_i_ref += 2;
1942 
1943   log_debug(redefine, class, annotation)
1944     ("type_index=%d  num_element_value_pairs=%d", type_index, num_element_value_pairs);
1945 
1946   int calc_num_element_value_pairs = 0;
1947   for (; calc_num_element_value_pairs < num_element_value_pairs;
1948        calc_num_element_value_pairs++) {
1949     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1950       // not enough room for another element_name_index, let alone
1951       // the rest of another component
1952       log_debug(redefine, class, annotation)("length() is too small for element_name_index");
1953       return false;
1954     }
1955 
1956     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1957                               annotations_typeArray, byte_i_ref,
1958                               "element_name_index", THREAD);
1959 
1960     log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
1961 
1962     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1963            byte_i_ref, THREAD)) {
1964       log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
1965       // propagate failure back to caller
1966       return false;
1967     }
1968   } // end for each component
1969   assert(num_element_value_pairs == calc_num_element_value_pairs,
1970     "sanity check");
1971 
1972   return true;
1973 } // end rewrite_cp_refs_in_annotation_struct()
1974 
1975 
1976 // Rewrite a constant pool reference at the current position in
1977 // annotations_typeArray if needed. Returns the original constant
1978 // pool reference if a rewrite was not needed or the new constant
1979 // pool reference if a rewrite was needed.
1980 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1981      AnnotationArray* annotations_typeArray, int &byte_i_ref,
1982      const char * trace_mesg, TRAPS) {
1983 
1984   address cp_index_addr = (address)
1985     annotations_typeArray->adr_at(byte_i_ref);
1986   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1987   u2 new_cp_index = find_new_index(old_cp_index);
1988   if (new_cp_index != 0) {
1989     log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
1990     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1991     old_cp_index = new_cp_index;
1992   }
1993   byte_i_ref += 2;
1994   return old_cp_index;
1995 }
1996 
1997 
1998 // Rewrite constant pool references in the element_value portion of an
1999 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2000 // the 2nd-edition of the VM spec:
2001 //
2002 // struct element_value {
2003 //   u1 tag;
2004 //   union {
2005 //     u2 const_value_index;
2006 //     {
2007 //       u2 type_name_index;
2008 //       u2 const_name_index;
2009 //     } enum_const_value;
2010 //     u2 class_info_index;
2011 //     annotation annotation_value;
2012 //     struct {
2013 //       u2 num_values;
2014 //       element_value values[num_values];
2015 //     } array_value;
2016 //   } value;
2017 // }
2018 //
2019 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2020        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2021 
2022   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2023     // not enough room for a tag let alone the rest of an element_value
2024     log_debug(redefine, class, annotation)("length() is too small for a tag");
2025     return false;
2026   }
2027 
2028   u1 tag = annotations_typeArray->at(byte_i_ref);
2029   byte_i_ref++;
2030   log_debug(redefine, class, annotation)("tag='%c'", tag);
2031 
2032   switch (tag) {
2033     // These BaseType tag values are from Table 4.2 in VM spec:
2034     case 'B':  // byte
2035     case 'C':  // char
2036     case 'D':  // double
2037     case 'F':  // float
2038     case 'I':  // int
2039     case 'J':  // long
2040     case 'S':  // short
2041     case 'Z':  // boolean
2042 
2043     // The remaining tag values are from Table 4.8 in the 2nd-edition of
2044     // the VM spec:
2045     case 's':
2046     {
2047       // For the above tag values (including the BaseType values),
2048       // value.const_value_index is right union field.
2049 
2050       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2051         // not enough room for a const_value_index
2052         log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2053         return false;
2054       }
2055 
2056       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2057                                annotations_typeArray, byte_i_ref,
2058                                "const_value_index", THREAD);
2059 
2060       log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2061     } break;
2062 
2063     case 'e':
2064     {
2065       // for the above tag value, value.enum_const_value is right union field
2066 
2067       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2068         // not enough room for a enum_const_value
2069         log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2070         return false;
2071       }
2072 
2073       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2074                              annotations_typeArray, byte_i_ref,
2075                              "type_name_index", THREAD);
2076 
2077       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2078                               annotations_typeArray, byte_i_ref,
2079                               "const_name_index", THREAD);
2080 
2081       log_debug(redefine, class, annotation)
2082         ("type_name_index=%d  const_name_index=%d", type_name_index, const_name_index);
2083     } break;
2084 
2085     case 'c':
2086     {
2087       // for the above tag value, value.class_info_index is right union field
2088 
2089       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2090         // not enough room for a class_info_index
2091         log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2092         return false;
2093       }
2094 
2095       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2096                               annotations_typeArray, byte_i_ref,
2097                               "class_info_index", THREAD);
2098 
2099       log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2100     } break;
2101 
2102     case '@':
2103       // For the above tag value, value.attr_value is the right union
2104       // field. This is a nested annotation.
2105       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2106              byte_i_ref, THREAD)) {
2107         // propagate failure back to caller
2108         return false;
2109       }
2110       break;
2111 
2112     case '[':
2113     {
2114       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2115         // not enough room for a num_values field
2116         log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2117         return false;
2118       }
2119 
2120       // For the above tag value, value.array_value is the right union
2121       // field. This is an array of nested element_value.
2122       u2 num_values = Bytes::get_Java_u2((address)
2123                         annotations_typeArray->adr_at(byte_i_ref));
2124       byte_i_ref += 2;
2125       log_debug(redefine, class, annotation)("num_values=%d", num_values);
2126 
2127       int calc_num_values = 0;
2128       for (; calc_num_values < num_values; calc_num_values++) {
2129         if (!rewrite_cp_refs_in_element_value(
2130                annotations_typeArray, byte_i_ref, THREAD)) {
2131           log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2132           // propagate failure back to caller
2133           return false;
2134         }
2135       }
2136       assert(num_values == calc_num_values, "sanity check");
2137     } break;
2138 
2139     default:
2140       log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2141       return false;
2142   } // end decode tag field
2143 
2144   return true;
2145 } // end rewrite_cp_refs_in_element_value()
2146 
2147 
2148 // Rewrite constant pool references in a fields_annotations field.
2149 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2150        InstanceKlass* scratch_class, TRAPS) {
2151 
2152   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2153 
2154   if (fields_annotations == NULL || fields_annotations->length() == 0) {
2155     // no fields_annotations so nothing to do
2156     return true;
2157   }
2158 
2159   log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2160 
2161   for (int i = 0; i < fields_annotations->length(); i++) {
2162     AnnotationArray* field_annotations = fields_annotations->at(i);
2163     if (field_annotations == NULL || field_annotations->length() == 0) {
2164       // this field does not have any annotations so skip it
2165       continue;
2166     }
2167 
2168     int byte_i = 0;  // byte index into field_annotations
2169     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2170            THREAD)) {
2171       log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2172       // propagate failure back to caller
2173       return false;
2174     }
2175   }
2176 
2177   return true;
2178 } // end rewrite_cp_refs_in_fields_annotations()
2179 
2180 
2181 // Rewrite constant pool references in a methods_annotations field.
2182 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2183        InstanceKlass* scratch_class, TRAPS) {
2184 
2185   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2186     Method* m = scratch_class->methods()->at(i);
2187     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2188 
2189     if (method_annotations == NULL || method_annotations->length() == 0) {
2190       // this method does not have any annotations so skip it
2191       continue;
2192     }
2193 
2194     int byte_i = 0;  // byte index into method_annotations
2195     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2196            THREAD)) {
2197       log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2198       // propagate failure back to caller
2199       return false;
2200     }
2201   }
2202 
2203   return true;
2204 } // end rewrite_cp_refs_in_methods_annotations()
2205 
2206 
2207 // Rewrite constant pool references in a methods_parameter_annotations
2208 // field. This "structure" is adapted from the
2209 // RuntimeVisibleParameterAnnotations_attribute described in section
2210 // 4.8.17 of the 2nd-edition of the VM spec:
2211 //
2212 // methods_parameter_annotations_typeArray {
2213 //   u1 num_parameters;
2214 //   {
2215 //     u2 num_annotations;
2216 //     annotation annotations[num_annotations];
2217 //   } parameter_annotations[num_parameters];
2218 // }
2219 //
2220 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2221        InstanceKlass* scratch_class, TRAPS) {
2222 
2223   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2224     Method* m = scratch_class->methods()->at(i);
2225     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2226     if (method_parameter_annotations == NULL
2227         || method_parameter_annotations->length() == 0) {
2228       // this method does not have any parameter annotations so skip it
2229       continue;
2230     }
2231 
2232     if (method_parameter_annotations->length() < 1) {
2233       // not enough room for a num_parameters field
2234       log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2235       return false;
2236     }
2237 
2238     int byte_i = 0;  // byte index into method_parameter_annotations
2239 
2240     u1 num_parameters = method_parameter_annotations->at(byte_i);
2241     byte_i++;
2242 
2243     log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2244 
2245     int calc_num_parameters = 0;
2246     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2247       if (!rewrite_cp_refs_in_annotations_typeArray(
2248              method_parameter_annotations, byte_i, THREAD)) {
2249         log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2250         // propagate failure back to caller
2251         return false;
2252       }
2253     }
2254     assert(num_parameters == calc_num_parameters, "sanity check");
2255   }
2256 
2257   return true;
2258 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2259 
2260 
2261 // Rewrite constant pool references in a methods_default_annotations
2262 // field. This "structure" is adapted from the AnnotationDefault_attribute
2263 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2264 //
2265 // methods_default_annotations_typeArray {
2266 //   element_value default_value;
2267 // }
2268 //
2269 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2270        InstanceKlass* scratch_class, TRAPS) {
2271 
2272   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2273     Method* m = scratch_class->methods()->at(i);
2274     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2275     if (method_default_annotations == NULL
2276         || method_default_annotations->length() == 0) {
2277       // this method does not have any default annotations so skip it
2278       continue;
2279     }
2280 
2281     int byte_i = 0;  // byte index into method_default_annotations
2282 
2283     if (!rewrite_cp_refs_in_element_value(
2284            method_default_annotations, byte_i, THREAD)) {
2285       log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2286       // propagate failure back to caller
2287       return false;
2288     }
2289   }
2290 
2291   return true;
2292 } // end rewrite_cp_refs_in_methods_default_annotations()
2293 
2294 
2295 // Rewrite constant pool references in a class_type_annotations field.
2296 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2297        InstanceKlass* scratch_class, TRAPS) {
2298 
2299   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2300   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2301     // no class_type_annotations so nothing to do
2302     return true;
2303   }
2304 
2305   log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2306 
2307   int byte_i = 0;  // byte index into class_type_annotations
2308   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2309       byte_i, "ClassFile", THREAD);
2310 } // end rewrite_cp_refs_in_class_type_annotations()
2311 
2312 
2313 // Rewrite constant pool references in a fields_type_annotations field.
2314 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2315        InstanceKlass* scratch_class, TRAPS) {
2316 
2317   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2318   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2319     // no fields_type_annotations so nothing to do
2320     return true;
2321   }
2322 
2323   log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2324 
2325   for (int i = 0; i < fields_type_annotations->length(); i++) {
2326     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2327     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2328       // this field does not have any annotations so skip it
2329       continue;
2330     }
2331 
2332     int byte_i = 0;  // byte index into field_type_annotations
2333     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2334            byte_i, "field_info", THREAD)) {
2335       log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2336       // propagate failure back to caller
2337       return false;
2338     }
2339   }
2340 
2341   return true;
2342 } // end rewrite_cp_refs_in_fields_type_annotations()
2343 
2344 
2345 // Rewrite constant pool references in a methods_type_annotations field.
2346 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2347        InstanceKlass* scratch_class, TRAPS) {
2348 
2349   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2350     Method* m = scratch_class->methods()->at(i);
2351     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2352 
2353     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2354       // this method does not have any annotations so skip it
2355       continue;
2356     }
2357 
2358     log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2359 
2360     int byte_i = 0;  // byte index into method_type_annotations
2361     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2362            byte_i, "method_info", THREAD)) {
2363       log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2364       // propagate failure back to caller
2365       return false;
2366     }
2367   }
2368 
2369   return true;
2370 } // end rewrite_cp_refs_in_methods_type_annotations()
2371 
2372 
2373 // Rewrite constant pool references in a type_annotations
2374 // field. This "structure" is adapted from the
2375 // RuntimeVisibleTypeAnnotations_attribute described in
2376 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2377 //
2378 // type_annotations_typeArray {
2379 //   u2              num_annotations;
2380 //   type_annotation annotations[num_annotations];
2381 // }
2382 //
2383 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2384        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2385        const char * location_mesg, TRAPS) {
2386 
2387   if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2388     // not enough room for num_annotations field
2389     log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2390     return false;
2391   }
2392 
2393   u2 num_annotations = Bytes::get_Java_u2((address)
2394                          type_annotations_typeArray->adr_at(byte_i_ref));
2395   byte_i_ref += 2;
2396 
2397   log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2398 
2399   int calc_num_annotations = 0;
2400   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2401     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2402            byte_i_ref, location_mesg, THREAD)) {
2403       log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2404       // propagate failure back to caller
2405       return false;
2406     }
2407   }
2408   assert(num_annotations == calc_num_annotations, "sanity check");
2409 
2410   if (byte_i_ref != type_annotations_typeArray->length()) {
2411     log_debug(redefine, class, annotation)
2412       ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2413        byte_i_ref, type_annotations_typeArray->length());
2414     return false;
2415   }
2416 
2417   return true;
2418 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2419 
2420 
2421 // Rewrite constant pool references in a type_annotation
2422 // field. This "structure" is adapted from the
2423 // RuntimeVisibleTypeAnnotations_attribute described in
2424 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2425 //
2426 // type_annotation {
2427 //   u1 target_type;
2428 //   union {
2429 //     type_parameter_target;
2430 //     supertype_target;
2431 //     type_parameter_bound_target;
2432 //     empty_target;
2433 //     method_formal_parameter_target;
2434 //     throws_target;
2435 //     localvar_target;
2436 //     catch_target;
2437 //     offset_target;
2438 //     type_argument_target;
2439 //   } target_info;
2440 //   type_path target_path;
2441 //   annotation anno;
2442 // }
2443 //
2444 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2445        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2446        const char * location_mesg, TRAPS) {
2447 
2448   if (!skip_type_annotation_target(type_annotations_typeArray,
2449          byte_i_ref, location_mesg, THREAD)) {
2450     return false;
2451   }
2452 
2453   if (!skip_type_annotation_type_path(type_annotations_typeArray,
2454          byte_i_ref, THREAD)) {
2455     return false;
2456   }
2457 
2458   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2459          byte_i_ref, THREAD)) {
2460     return false;
2461   }
2462 
2463   return true;
2464 } // end rewrite_cp_refs_in_type_annotation_struct()
2465 
2466 
2467 // Read, verify and skip over the target_type and target_info part
2468 // so that rewriting can continue in the later parts of the struct.
2469 //
2470 // u1 target_type;
2471 // union {
2472 //   type_parameter_target;
2473 //   supertype_target;
2474 //   type_parameter_bound_target;
2475 //   empty_target;
2476 //   method_formal_parameter_target;
2477 //   throws_target;
2478 //   localvar_target;
2479 //   catch_target;
2480 //   offset_target;
2481 //   type_argument_target;
2482 // } target_info;
2483 //
2484 bool VM_RedefineClasses::skip_type_annotation_target(
2485        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2486        const char * location_mesg, TRAPS) {
2487 
2488   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2489     // not enough room for a target_type let alone the rest of a type_annotation
2490     log_debug(redefine, class, annotation)("length() is too small for a target_type");
2491     return false;
2492   }
2493 
2494   u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2495   byte_i_ref += 1;
2496   log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2497   log_debug(redefine, class, annotation)("location=%s", location_mesg);
2498 
2499   // Skip over target_info
2500   switch (target_type) {
2501     case 0x00:
2502     // kind: type parameter declaration of generic class or interface
2503     // location: ClassFile
2504     case 0x01:
2505     // kind: type parameter declaration of generic method or constructor
2506     // location: method_info
2507 
2508     {
2509       // struct:
2510       // type_parameter_target {
2511       //   u1 type_parameter_index;
2512       // }
2513       //
2514       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2515         log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2516         return false;
2517       }
2518 
2519       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2520       byte_i_ref += 1;
2521 
2522       log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2523     } break;
2524 
2525     case 0x10:
2526     // kind: type in extends clause of class or interface declaration
2527     //       (including the direct superclass of an anonymous class declaration),
2528     //       or in implements clause of interface declaration
2529     // location: ClassFile
2530 
2531     {
2532       // struct:
2533       // supertype_target {
2534       //   u2 supertype_index;
2535       // }
2536       //
2537       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2538         log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2539         return false;
2540       }
2541 
2542       u2 supertype_index = Bytes::get_Java_u2((address)
2543                              type_annotations_typeArray->adr_at(byte_i_ref));
2544       byte_i_ref += 2;
2545 
2546       log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2547     } break;
2548 
2549     case 0x11:
2550     // kind: type in bound of type parameter declaration of generic class or interface
2551     // location: ClassFile
2552     case 0x12:
2553     // kind: type in bound of type parameter declaration of generic method or constructor
2554     // location: method_info
2555 
2556     {
2557       // struct:
2558       // type_parameter_bound_target {
2559       //   u1 type_parameter_index;
2560       //   u1 bound_index;
2561       // }
2562       //
2563       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2564         log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2565         return false;
2566       }
2567 
2568       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2569       byte_i_ref += 1;
2570       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2571       byte_i_ref += 1;
2572 
2573       log_debug(redefine, class, annotation)
2574         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2575     } break;
2576 
2577     case 0x13:
2578     // kind: type in field declaration
2579     // location: field_info
2580     case 0x14:
2581     // kind: return type of method, or type of newly constructed object
2582     // location: method_info
2583     case 0x15:
2584     // kind: receiver type of method or constructor
2585     // location: method_info
2586 
2587     {
2588       // struct:
2589       // empty_target {
2590       // }
2591       //
2592       log_debug(redefine, class, annotation)("empty_target");
2593     } break;
2594 
2595     case 0x16:
2596     // kind: type in formal parameter declaration of method, constructor, or lambda expression
2597     // location: method_info
2598 
2599     {
2600       // struct:
2601       // formal_parameter_target {
2602       //   u1 formal_parameter_index;
2603       // }
2604       //
2605       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2606         log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2607         return false;
2608       }
2609 
2610       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2611       byte_i_ref += 1;
2612 
2613       log_debug(redefine, class, annotation)
2614         ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2615     } break;
2616 
2617     case 0x17:
2618     // kind: type in throws clause of method or constructor
2619     // location: method_info
2620 
2621     {
2622       // struct:
2623       // throws_target {
2624       //   u2 throws_type_index
2625       // }
2626       //
2627       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2628         log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2629         return false;
2630       }
2631 
2632       u2 throws_type_index = Bytes::get_Java_u2((address)
2633                                type_annotations_typeArray->adr_at(byte_i_ref));
2634       byte_i_ref += 2;
2635 
2636       log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2637     } break;
2638 
2639     case 0x40:
2640     // kind: type in local variable declaration
2641     // location: Code
2642     case 0x41:
2643     // kind: type in resource variable declaration
2644     // location: Code
2645 
2646     {
2647       // struct:
2648       // localvar_target {
2649       //   u2 table_length;
2650       //   struct {
2651       //     u2 start_pc;
2652       //     u2 length;
2653       //     u2 index;
2654       //   } table[table_length];
2655       // }
2656       //
2657       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2658         // not enough room for a table_length let alone the rest of a localvar_target
2659         log_debug(redefine, class, annotation)("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       log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2668 
2669       int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2670       int table_size = table_length * table_struct_size;
2671 
2672       if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2673         // not enough room for a table
2674         log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2675         return false;
2676       }
2677 
2678       // Skip over table
2679       byte_i_ref += table_size;
2680     } break;
2681 
2682     case 0x42:
2683     // kind: type in exception parameter declaration
2684     // location: Code
2685 
2686     {
2687       // struct:
2688       // catch_target {
2689       //   u2 exception_table_index;
2690       // }
2691       //
2692       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2693         log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2694         return false;
2695       }
2696 
2697       u2 exception_table_index = Bytes::get_Java_u2((address)
2698                                    type_annotations_typeArray->adr_at(byte_i_ref));
2699       byte_i_ref += 2;
2700 
2701       log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2702     } break;
2703 
2704     case 0x43:
2705     // kind: type in instanceof expression
2706     // location: Code
2707     case 0x44:
2708     // kind: type in new expression
2709     // location: Code
2710     case 0x45:
2711     // kind: type in method reference expression using ::new
2712     // location: Code
2713     case 0x46:
2714     // kind: type in method reference expression using ::Identifier
2715     // location: Code
2716 
2717     {
2718       // struct:
2719       // offset_target {
2720       //   u2 offset;
2721       // }
2722       //
2723       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2724         log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2725         return false;
2726       }
2727 
2728       u2 offset = Bytes::get_Java_u2((address)
2729                     type_annotations_typeArray->adr_at(byte_i_ref));
2730       byte_i_ref += 2;
2731 
2732       log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2733     } break;
2734 
2735     case 0x47:
2736     // kind: type in cast expression
2737     // location: Code
2738     case 0x48:
2739     // kind: type argument for generic constructor in new expression or
2740     //       explicit constructor invocation statement
2741     // location: Code
2742     case 0x49:
2743     // kind: type argument for generic method in method invocation expression
2744     // location: Code
2745     case 0x4A:
2746     // kind: type argument for generic constructor in method reference expression using ::new
2747     // location: Code
2748     case 0x4B:
2749     // kind: type argument for generic method in method reference expression using ::Identifier
2750     // location: Code
2751 
2752     {
2753       // struct:
2754       // type_argument_target {
2755       //   u2 offset;
2756       //   u1 type_argument_index;
2757       // }
2758       //
2759       if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2760         log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
2761         return false;
2762       }
2763 
2764       u2 offset = Bytes::get_Java_u2((address)
2765                     type_annotations_typeArray->adr_at(byte_i_ref));
2766       byte_i_ref += 2;
2767       u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2768       byte_i_ref += 1;
2769 
2770       log_debug(redefine, class, annotation)
2771         ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
2772     } break;
2773 
2774     default:
2775       log_debug(redefine, class, annotation)("unknown target_type");
2776 #ifdef ASSERT
2777       ShouldNotReachHere();
2778 #endif
2779       return false;
2780   }
2781 
2782   return true;
2783 } // end skip_type_annotation_target()
2784 
2785 
2786 // Read, verify and skip over the type_path part so that rewriting
2787 // can continue in the later parts of the struct.
2788 //
2789 // type_path {
2790 //   u1 path_length;
2791 //   {
2792 //     u1 type_path_kind;
2793 //     u1 type_argument_index;
2794 //   } path[path_length];
2795 // }
2796 //
2797 bool VM_RedefineClasses::skip_type_annotation_type_path(
2798        AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2799 
2800   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2801     // not enough room for a path_length let alone the rest of the type_path
2802     log_debug(redefine, class, annotation)("length() is too small for a type_path");
2803     return false;
2804   }
2805 
2806   u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2807   byte_i_ref += 1;
2808 
2809   log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
2810 
2811   int calc_path_length = 0;
2812   for (; calc_path_length < path_length; calc_path_length++) {
2813     if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2814       // not enough room for a path
2815       log_debug(redefine, class, annotation)
2816         ("length() is too small for path entry %d of %d", calc_path_length, path_length);
2817       return false;
2818     }
2819 
2820     u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2821     byte_i_ref += 1;
2822     u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2823     byte_i_ref += 1;
2824 
2825     log_debug(redefine, class, annotation)
2826       ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2827        calc_path_length, type_path_kind, type_argument_index);
2828 
2829     if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2830       // not enough room for a path
2831       log_debug(redefine, class, annotation)("inconsistent type_path values");
2832       return false;
2833     }
2834   }
2835   assert(path_length == calc_path_length, "sanity check");
2836 
2837   return true;
2838 } // end skip_type_annotation_type_path()
2839 
2840 
2841 // Rewrite constant pool references in the method's stackmap table.
2842 // These "structures" are adapted from the StackMapTable_attribute that
2843 // is described in section 4.8.4 of the 6.0 version of the VM spec
2844 // (dated 2005.10.26):
2845 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2846 //
2847 // stack_map {
2848 //   u2 number_of_entries;
2849 //   stack_map_frame entries[number_of_entries];
2850 // }
2851 //
2852 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2853        const methodHandle& method, TRAPS) {
2854 
2855   if (!method->has_stackmap_table()) {
2856     return;
2857   }
2858 
2859   AnnotationArray* stackmap_data = method->stackmap_data();
2860   address stackmap_p = (address)stackmap_data->adr_at(0);
2861   address stackmap_end = stackmap_p + stackmap_data->length();
2862 
2863   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2864   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2865   stackmap_p += 2;
2866 
2867   log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
2868 
2869   // walk through each stack_map_frame
2870   u2 calc_number_of_entries = 0;
2871   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2872     // The stack_map_frame structure is a u1 frame_type followed by
2873     // 0 or more bytes of data:
2874     //
2875     // union stack_map_frame {
2876     //   same_frame;
2877     //   same_locals_1_stack_item_frame;
2878     //   same_locals_1_stack_item_frame_extended;
2879     //   chop_frame;
2880     //   same_frame_extended;
2881     //   append_frame;
2882     //   full_frame;
2883     // }
2884 
2885     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2886     u1 frame_type = *stackmap_p;
2887     stackmap_p++;
2888 
2889     // same_frame {
2890     //   u1 frame_type = SAME; /* 0-63 */
2891     // }
2892     if (frame_type <= 63) {
2893       // nothing more to do for same_frame
2894     }
2895 
2896     // same_locals_1_stack_item_frame {
2897     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2898     //   verification_type_info stack[1];
2899     // }
2900     else if (frame_type >= 64 && frame_type <= 127) {
2901       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2902         calc_number_of_entries, frame_type, THREAD);
2903     }
2904 
2905     // reserved for future use
2906     else if (frame_type >= 128 && frame_type <= 246) {
2907       // nothing more to do for reserved frame_types
2908     }
2909 
2910     // same_locals_1_stack_item_frame_extended {
2911     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2912     //   u2 offset_delta;
2913     //   verification_type_info stack[1];
2914     // }
2915     else if (frame_type == 247) {
2916       stackmap_p += 2;
2917       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2918         calc_number_of_entries, frame_type, THREAD);
2919     }
2920 
2921     // chop_frame {
2922     //   u1 frame_type = CHOP; /* 248-250 */
2923     //   u2 offset_delta;
2924     // }
2925     else if (frame_type >= 248 && frame_type <= 250) {
2926       stackmap_p += 2;
2927     }
2928 
2929     // same_frame_extended {
2930     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2931     //   u2 offset_delta;
2932     // }
2933     else if (frame_type == 251) {
2934       stackmap_p += 2;
2935     }
2936 
2937     // append_frame {
2938     //   u1 frame_type = APPEND; /* 252-254 */
2939     //   u2 offset_delta;
2940     //   verification_type_info locals[frame_type - 251];
2941     // }
2942     else if (frame_type >= 252 && frame_type <= 254) {
2943       assert(stackmap_p + 2 <= stackmap_end,
2944         "no room for offset_delta");
2945       stackmap_p += 2;
2946       u1 len = frame_type - 251;
2947       for (u1 i = 0; i < len; i++) {
2948         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2949           calc_number_of_entries, frame_type, THREAD);
2950       }
2951     }
2952 
2953     // full_frame {
2954     //   u1 frame_type = FULL_FRAME; /* 255 */
2955     //   u2 offset_delta;
2956     //   u2 number_of_locals;
2957     //   verification_type_info locals[number_of_locals];
2958     //   u2 number_of_stack_items;
2959     //   verification_type_info stack[number_of_stack_items];
2960     // }
2961     else if (frame_type == 255) {
2962       assert(stackmap_p + 2 + 2 <= stackmap_end,
2963         "no room for smallest full_frame");
2964       stackmap_p += 2;
2965 
2966       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2967       stackmap_p += 2;
2968 
2969       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2970         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2971           calc_number_of_entries, frame_type, THREAD);
2972       }
2973 
2974       // Use the largest size for the number_of_stack_items, but only get
2975       // the right number of bytes.
2976       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2977       stackmap_p += 2;
2978 
2979       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2980         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2981           calc_number_of_entries, frame_type, THREAD);
2982       }
2983     }
2984   } // end while there is a stack_map_frame
2985   assert(number_of_entries == calc_number_of_entries, "sanity check");
2986 } // end rewrite_cp_refs_in_stack_map_table()
2987 
2988 
2989 // Rewrite constant pool references in the verification type info
2990 // portion of the method's stackmap table. These "structures" are
2991 // adapted from the StackMapTable_attribute that is described in
2992 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2993 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2994 //
2995 // The verification_type_info structure is a u1 tag followed by 0 or
2996 // more bytes of data:
2997 //
2998 // union verification_type_info {
2999 //   Top_variable_info;
3000 //   Integer_variable_info;
3001 //   Float_variable_info;
3002 //   Long_variable_info;
3003 //   Double_variable_info;
3004 //   Null_variable_info;
3005 //   UninitializedThis_variable_info;
3006 //   Object_variable_info;
3007 //   Uninitialized_variable_info;
3008 // }
3009 //
3010 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3011        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3012        u1 frame_type, TRAPS) {
3013 
3014   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3015   u1 tag = *stackmap_p_ref;
3016   stackmap_p_ref++;
3017 
3018   switch (tag) {
3019   // Top_variable_info {
3020   //   u1 tag = ITEM_Top; /* 0 */
3021   // }
3022   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3023   case 0:  // fall through
3024 
3025   // Integer_variable_info {
3026   //   u1 tag = ITEM_Integer; /* 1 */
3027   // }
3028   case ITEM_Integer:  // fall through
3029 
3030   // Float_variable_info {
3031   //   u1 tag = ITEM_Float; /* 2 */
3032   // }
3033   case ITEM_Float:  // fall through
3034 
3035   // Double_variable_info {
3036   //   u1 tag = ITEM_Double; /* 3 */
3037   // }
3038   case ITEM_Double:  // fall through
3039 
3040   // Long_variable_info {
3041   //   u1 tag = ITEM_Long; /* 4 */
3042   // }
3043   case ITEM_Long:  // fall through
3044 
3045   // Null_variable_info {
3046   //   u1 tag = ITEM_Null; /* 5 */
3047   // }
3048   case ITEM_Null:  // fall through
3049 
3050   // UninitializedThis_variable_info {
3051   //   u1 tag = ITEM_UninitializedThis; /* 6 */
3052   // }
3053   case ITEM_UninitializedThis:
3054     // nothing more to do for the above tag types
3055     break;
3056 
3057   // Object_variable_info {
3058   //   u1 tag = ITEM_Object; /* 7 */
3059   //   u2 cpool_index;
3060   // }
3061   case ITEM_Object:
3062   {
3063     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3064     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3065     u2 new_cp_index = find_new_index(cpool_index);
3066     if (new_cp_index != 0) {
3067       log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3068       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3069       cpool_index = new_cp_index;
3070     }
3071     stackmap_p_ref += 2;
3072 
3073     log_debug(redefine, class, stackmap)
3074       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3075   } break;
3076 
3077   // Uninitialized_variable_info {
3078   //   u1 tag = ITEM_Uninitialized; /* 8 */
3079   //   u2 offset;
3080   // }
3081   case ITEM_Uninitialized:
3082     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3083     stackmap_p_ref += 2;
3084     break;
3085 
3086   default:
3087     log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3088     ShouldNotReachHere();
3089     break;
3090   } // end switch (tag)
3091 } // end rewrite_cp_refs_in_verification_type_info()
3092 
3093 
3094 // Change the constant pool associated with klass scratch_class to
3095 // scratch_cp. If shrink is true, then scratch_cp_length elements
3096 // are copied from scratch_cp to a smaller constant pool and the
3097 // smaller constant pool is associated with scratch_class.
3098 void VM_RedefineClasses::set_new_constant_pool(
3099        ClassLoaderData* loader_data,
3100        InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3101        int scratch_cp_length, TRAPS) {
3102   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3103 
3104   // scratch_cp is a merged constant pool and has enough space for a
3105   // worst case merge situation. We want to associate the minimum
3106   // sized constant pool with the klass to save space.
3107   ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3108   constantPoolHandle smaller_cp(THREAD, cp);
3109 
3110   // preserve version() value in the smaller copy
3111   int version = scratch_cp->version();
3112   assert(version != 0, "sanity check");
3113   smaller_cp->set_version(version);
3114 
3115   // attach klass to new constant pool
3116   // reference to the cp holder is needed for copy_operands()
3117   smaller_cp->set_pool_holder(scratch_class);
3118 
3119   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3120   if (HAS_PENDING_EXCEPTION) {
3121     // Exception is handled in the caller
3122     loader_data->add_to_deallocate_list(smaller_cp());
3123     return;
3124   }
3125   scratch_cp = smaller_cp;
3126 
3127   // attach new constant pool to klass
3128   scratch_class->set_constants(scratch_cp());
3129   scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3130 
3131   int i;  // for portability
3132 
3133   // update each field in klass to use new constant pool indices as needed
3134   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3135     jshort cur_index = fs.name_index();
3136     jshort new_index = find_new_index(cur_index);
3137     if (new_index != 0) {
3138       log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3139       fs.set_name_index(new_index);
3140     }
3141     cur_index = fs.signature_index();
3142     new_index = find_new_index(cur_index);
3143     if (new_index != 0) {
3144       log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3145       fs.set_signature_index(new_index);
3146     }
3147     cur_index = fs.initval_index();
3148     new_index = find_new_index(cur_index);
3149     if (new_index != 0) {
3150       log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3151       fs.set_initval_index(new_index);
3152     }
3153     cur_index = fs.generic_signature_index();
3154     new_index = find_new_index(cur_index);
3155     if (new_index != 0) {
3156       log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3157       fs.set_generic_signature_index(new_index);
3158     }
3159   } // end for each field
3160 
3161   // Update constant pool indices in the inner classes info to use
3162   // new constant indices as needed. The inner classes info is a
3163   // quadruple:
3164   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3165   InnerClassesIterator iter(scratch_class);
3166   for (; !iter.done(); iter.next()) {
3167     int cur_index = iter.inner_class_info_index();
3168     if (cur_index == 0) {
3169       continue;  // JVM spec. allows null inner class refs so skip it
3170     }
3171     int new_index = find_new_index(cur_index);
3172     if (new_index != 0) {
3173       log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3174       iter.set_inner_class_info_index(new_index);
3175     }
3176     cur_index = iter.outer_class_info_index();
3177     new_index = find_new_index(cur_index);
3178     if (new_index != 0) {
3179       log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3180       iter.set_outer_class_info_index(new_index);
3181     }
3182     cur_index = iter.inner_name_index();
3183     new_index = find_new_index(cur_index);
3184     if (new_index != 0) {
3185       log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3186       iter.set_inner_name_index(new_index);
3187     }
3188   } // end for each inner class
3189 
3190   // Attach each method in klass to the new constant pool and update
3191   // to use new constant pool indices as needed:
3192   Array<Method*>* methods = scratch_class->methods();
3193   for (i = methods->length() - 1; i >= 0; i--) {
3194     methodHandle method(THREAD, methods->at(i));
3195     method->set_constants(scratch_cp());
3196 
3197     int new_index = find_new_index(method->name_index());
3198     if (new_index != 0) {
3199       log_trace(redefine, class, constantpool)
3200         ("method-name_index change: %d to %d", method->name_index(), new_index);
3201       method->set_name_index(new_index);
3202     }
3203     new_index = find_new_index(method->signature_index());
3204     if (new_index != 0) {
3205       log_trace(redefine, class, constantpool)
3206         ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3207       method->set_signature_index(new_index);
3208     }
3209     new_index = find_new_index(method->generic_signature_index());
3210     if (new_index != 0) {
3211       log_trace(redefine, class, constantpool)
3212         ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3213       method->set_generic_signature_index(new_index);
3214     }
3215 
3216     // Update constant pool indices in the method's checked exception
3217     // table to use new constant indices as needed.
3218     int cext_length = method->checked_exceptions_length();
3219     if (cext_length > 0) {
3220       CheckedExceptionElement * cext_table =
3221         method->checked_exceptions_start();
3222       for (int j = 0; j < cext_length; j++) {
3223         int cur_index = cext_table[j].class_cp_index;
3224         int new_index = find_new_index(cur_index);
3225         if (new_index != 0) {
3226           log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3227           cext_table[j].class_cp_index = (u2)new_index;
3228         }
3229       } // end for each checked exception table entry
3230     } // end if there are checked exception table entries
3231 
3232     // Update each catch type index in the method's exception table
3233     // to use new constant pool indices as needed. The exception table
3234     // holds quadruple entries of the form:
3235     //   (beg_bci, end_bci, handler_bci, klass_index)
3236 
3237     ExceptionTable ex_table(method());
3238     int ext_length = ex_table.length();
3239 
3240     for (int j = 0; j < ext_length; j ++) {
3241       int cur_index = ex_table.catch_type_index(j);
3242       int new_index = find_new_index(cur_index);
3243       if (new_index != 0) {
3244         log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3245         ex_table.set_catch_type_index(j, new_index);
3246       }
3247     } // end for each exception table entry
3248 
3249     // Update constant pool indices in the method's local variable
3250     // table to use new constant indices as needed. The local variable
3251     // table hold sextuple entries of the form:
3252     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3253     int lvt_length = method->localvariable_table_length();
3254     if (lvt_length > 0) {
3255       LocalVariableTableElement * lv_table =
3256         method->localvariable_table_start();
3257       for (int j = 0; j < lvt_length; j++) {
3258         int cur_index = lv_table[j].name_cp_index;
3259         int new_index = find_new_index(cur_index);
3260         if (new_index != 0) {
3261           log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3262           lv_table[j].name_cp_index = (u2)new_index;
3263         }
3264         cur_index = lv_table[j].descriptor_cp_index;
3265         new_index = find_new_index(cur_index);
3266         if (new_index != 0) {
3267           log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3268           lv_table[j].descriptor_cp_index = (u2)new_index;
3269         }
3270         cur_index = lv_table[j].signature_cp_index;
3271         new_index = find_new_index(cur_index);
3272         if (new_index != 0) {
3273           log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3274           lv_table[j].signature_cp_index = (u2)new_index;
3275         }
3276       } // end for each local variable table entry
3277     } // end if there are local variable table entries
3278 
3279     rewrite_cp_refs_in_stack_map_table(method, THREAD);
3280   } // end for each method
3281 } // end set_new_constant_pool()
3282 
3283 
3284 // Unevolving classes may point to methods of the_class directly
3285 // from their constant pool caches, itables, and/or vtables. We
3286 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3287 // to fix up these pointers.
3288 
3289 // Adjust cpools and vtables closure
3290 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3291 
3292   // This is a very busy routine. We don't want too much tracing
3293   // printed out.
3294   bool trace_name_printed = false;
3295   InstanceKlass *the_class = InstanceKlass::cast(_the_class);
3296 
3297   // If the class being redefined is java.lang.Object, we need to fix all
3298   // array class vtables also
3299   if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) {
3300     k->vtable().adjust_method_entries(the_class, &trace_name_printed);
3301 
3302   } else if (k->is_instance_klass()) {
3303     HandleMark hm(_thread);
3304     InstanceKlass *ik = InstanceKlass::cast(k);
3305 
3306     // HotSpot specific optimization! HotSpot does not currently
3307     // support delegation from the bootstrap class loader to a
3308     // user-defined class loader. This means that if the bootstrap
3309     // class loader is the initiating class loader, then it will also
3310     // be the defining class loader. This also means that classes
3311     // loaded by the bootstrap class loader cannot refer to classes
3312     // loaded by a user-defined class loader. Note: a user-defined
3313     // class loader can delegate to the bootstrap class loader.
3314     //
3315     // If the current class being redefined has a user-defined class
3316     // loader as its defining class loader, then we can skip all
3317     // classes loaded by the bootstrap class loader.
3318     bool is_user_defined = (_the_class->class_loader() != NULL);
3319     if (is_user_defined && ik->class_loader() == NULL) {
3320       return;
3321     }
3322 
3323     // Fix the vtable embedded in the_class and subclasses of the_class,
3324     // if one exists. We discard scratch_class and we don't keep an
3325     // InstanceKlass around to hold obsolete methods so we don't have
3326     // any other InstanceKlass embedded vtables to update. The vtable
3327     // holds the Method*s for virtual (but not final) methods.
3328     // Default methods, or concrete methods in interfaces are stored
3329     // in the vtable, so if an interface changes we need to check
3330     // adjust_method_entries() for every InstanceKlass, which will also
3331     // adjust the default method vtable indices.
3332     // We also need to adjust any default method entries that are
3333     // not yet in the vtable, because the vtable setup is in progress.
3334     // This must be done after we adjust the default_methods and
3335     // default_vtable_indices for methods already in the vtable.
3336     // If redefining Unsafe, walk all the vtables looking for entries.
3337     if (ik->vtable_length() > 0 && (_the_class->is_interface()
3338         || _the_class == SystemDictionary::internal_Unsafe_klass()
3339         || ik->is_subtype_of(_the_class))) {
3340       // ik->vtable() creates a wrapper object; rm cleans it up
3341       ResourceMark rm(_thread);
3342 
3343       ik->vtable().adjust_method_entries(the_class, &trace_name_printed);
3344       ik->adjust_default_methods(the_class, &trace_name_printed);
3345     }
3346 
3347     // If the current class has an itable and we are either redefining an
3348     // interface or if the current class is a subclass of the_class, then
3349     // we potentially have to fix the itable. If we are redefining an
3350     // interface, then we have to call adjust_method_entries() for
3351     // every InstanceKlass that has an itable since there isn't a
3352     // subclass relationship between an interface and an InstanceKlass.
3353     // If redefining Unsafe, walk all the itables looking for entries.
3354     if (ik->itable_length() > 0 && (_the_class->is_interface()
3355         || _the_class == SystemDictionary::internal_Unsafe_klass()
3356         || ik->is_subclass_of(_the_class))) {
3357       ResourceMark rm(_thread);
3358       ik->itable().adjust_method_entries(the_class, &trace_name_printed);
3359     }
3360 
3361     // The constant pools in other classes (other_cp) can refer to
3362     // methods in the_class. We have to update method information in
3363     // other_cp's cache. If other_cp has a previous version, then we
3364     // have to repeat the process for each previous version. The
3365     // constant pool cache holds the Method*s for non-virtual
3366     // methods and for virtual, final methods.
3367     //
3368     // Special case: if the current class is the_class, then new_cp
3369     // has already been attached to the_class and old_cp has already
3370     // been added as a previous version. The new_cp doesn't have any
3371     // cached references to old methods so it doesn't need to be
3372     // updated. We can simply start with the previous version(s) in
3373     // that case.
3374     constantPoolHandle other_cp;
3375     ConstantPoolCache* cp_cache;
3376 
3377     if (ik != _the_class) {
3378       // this klass' constant pool cache may need adjustment
3379       other_cp = constantPoolHandle(ik->constants());
3380       cp_cache = other_cp->cache();
3381       if (cp_cache != NULL) {
3382         cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3383       }
3384     }
3385 
3386     // the previous versions' constant pool caches may need adjustment
3387     for (InstanceKlass* pv_node = ik->previous_versions();
3388          pv_node != NULL;
3389          pv_node = pv_node->previous_versions()) {
3390       cp_cache = pv_node->constants()->cache();
3391       if (cp_cache != NULL) {
3392         cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3393       }
3394     }
3395   }
3396 }
3397 
3398 // Clean method data for this class
3399 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3400   if (k->is_instance_klass()) {
3401     InstanceKlass *ik = InstanceKlass::cast(k);
3402     // Clean MethodData of this class's methods so they don't refer to
3403     // old methods that are no longer running.
3404     Array<Method*>* methods = ik->methods();
3405     int num_methods = methods->length();
3406     for (int index = 0; index < num_methods; ++index) {
3407       if (methods->at(index)->method_data() != NULL) {
3408         methods->at(index)->method_data()->clean_weak_method_links();
3409       }
3410     }
3411   }
3412 }
3413 
3414 void VM_RedefineClasses::update_jmethod_ids() {
3415   for (int j = 0; j < _matching_methods_length; ++j) {
3416     Method* old_method = _matching_old_methods[j];
3417     jmethodID jmid = old_method->find_jmethod_id_or_null();
3418     if (jmid != NULL) {
3419       // There is a jmethodID, change it to point to the new method
3420       methodHandle new_method_h(_matching_new_methods[j]);
3421       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3422       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3423              "should be replaced");
3424     }
3425   }
3426 }
3427 
3428 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3429   int emcp_method_count = 0;
3430   int obsolete_count = 0;
3431   int old_index = 0;
3432   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3433     Method* old_method = _matching_old_methods[j];
3434     Method* new_method = _matching_new_methods[j];
3435     Method* old_array_method;
3436 
3437     // Maintain an old_index into the _old_methods array by skipping
3438     // deleted methods
3439     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3440       ++old_index;
3441     }
3442 
3443     if (MethodComparator::methods_EMCP(old_method, new_method)) {
3444       // The EMCP definition from JSR-163 requires the bytecodes to be
3445       // the same with the exception of constant pool indices which may
3446       // differ. However, the constants referred to by those indices
3447       // must be the same.
3448       //
3449       // We use methods_EMCP() for comparison since constant pool
3450       // merging can remove duplicate constant pool entries that were
3451       // present in the old method and removed from the rewritten new
3452       // method. A faster binary comparison function would consider the
3453       // old and new methods to be different when they are actually
3454       // EMCP.
3455       //
3456       // The old and new methods are EMCP and you would think that we
3457       // could get rid of one of them here and now and save some space.
3458       // However, the concept of EMCP only considers the bytecodes and
3459       // the constant pool entries in the comparison. Other things,
3460       // e.g., the line number table (LNT) or the local variable table
3461       // (LVT) don't count in the comparison. So the new (and EMCP)
3462       // method can have a new LNT that we need so we can't just
3463       // overwrite the new method with the old method.
3464       //
3465       // When this routine is called, we have already attached the new
3466       // methods to the_class so the old methods are effectively
3467       // overwritten. However, if an old method is still executing,
3468       // then the old method cannot be collected until sometime after
3469       // the old method call has returned. So the overwriting of old
3470       // methods by new methods will save us space except for those
3471       // (hopefully few) old methods that are still executing.
3472       //
3473       // A method refers to a ConstMethod* and this presents another
3474       // possible avenue to space savings. The ConstMethod* in the
3475       // new method contains possibly new attributes (LNT, LVT, etc).
3476       // At first glance, it seems possible to save space by replacing
3477       // the ConstMethod* in the old method with the ConstMethod*
3478       // from the new method. The old and new methods would share the
3479       // same ConstMethod* and we would save the space occupied by
3480       // the old ConstMethod*. However, the ConstMethod* contains
3481       // a back reference to the containing method. Sharing the
3482       // ConstMethod* between two methods could lead to confusion in
3483       // the code that uses the back reference. This would lead to
3484       // brittle code that could be broken in non-obvious ways now or
3485       // in the future.
3486       //
3487       // Another possibility is to copy the ConstMethod* from the new
3488       // method to the old method and then overwrite the new method with
3489       // the old method. Since the ConstMethod* contains the bytecodes
3490       // for the method embedded in the oop, this option would change
3491       // the bytecodes out from under any threads executing the old
3492       // method and make the thread's bcp invalid. Since EMCP requires
3493       // that the bytecodes be the same modulo constant pool indices, it
3494       // is straight forward to compute the correct new bcp in the new
3495       // ConstMethod* from the old bcp in the old ConstMethod*. The
3496       // time consuming part would be searching all the frames in all
3497       // of the threads to find all of the calls to the old method.
3498       //
3499       // It looks like we will have to live with the limited savings
3500       // that we get from effectively overwriting the old methods
3501       // when the new methods are attached to the_class.
3502 
3503       // Count number of methods that are EMCP.  The method will be marked
3504       // old but not obsolete if it is EMCP.
3505       emcp_method_count++;
3506 
3507       // An EMCP method is _not_ obsolete. An obsolete method has a
3508       // different jmethodID than the current method. An EMCP method
3509       // has the same jmethodID as the current method. Having the
3510       // same jmethodID for all EMCP versions of a method allows for
3511       // a consistent view of the EMCP methods regardless of which
3512       // EMCP method you happen to have in hand. For example, a
3513       // breakpoint set in one EMCP method will work for all EMCP
3514       // versions of the method including the current one.
3515     } else {
3516       // mark obsolete methods as such
3517       old_method->set_is_obsolete();
3518       obsolete_count++;
3519 
3520       // obsolete methods need a unique idnum so they become new entries in
3521       // the jmethodID cache in InstanceKlass
3522       assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3523       u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3524       if (num != ConstMethod::UNSET_IDNUM) {
3525         old_method->set_method_idnum(num);
3526       }
3527 
3528       // With tracing we try not to "yack" too much. The position of
3529       // this trace assumes there are fewer obsolete methods than
3530       // EMCP methods.
3531       if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3532         ResourceMark rm;
3533         log_trace(redefine, class, obsolete, mark)
3534           ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3535       }
3536     }
3537     old_method->set_is_old();
3538   }
3539   for (int i = 0; i < _deleted_methods_length; ++i) {
3540     Method* old_method = _deleted_methods[i];
3541 
3542     assert(!old_method->has_vtable_index(),
3543            "cannot delete methods with vtable entries");;
3544 
3545     // Mark all deleted methods as old, obsolete and deleted
3546     old_method->set_is_deleted();
3547     old_method->set_is_old();
3548     old_method->set_is_obsolete();
3549     ++obsolete_count;
3550     // With tracing we try not to "yack" too much. The position of
3551     // this trace assumes there are fewer obsolete methods than
3552     // EMCP methods.
3553     if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3554       ResourceMark rm;
3555       log_trace(redefine, class, obsolete, mark)
3556         ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3557     }
3558   }
3559   assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3560     "sanity check");
3561   log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3562   return emcp_method_count;
3563 }
3564 
3565 // This internal class transfers the native function registration from old methods
3566 // to new methods.  It is designed to handle both the simple case of unchanged
3567 // native methods and the complex cases of native method prefixes being added and/or
3568 // removed.
3569 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3570 //
3571 // This class is used after the new methods have been installed in "the_class".
3572 //
3573 // So, for example, the following must be handled.  Where 'm' is a method and
3574 // a number followed by an underscore is a prefix.
3575 //
3576 //                                      Old Name    New Name
3577 // Simple transfer to new method        m       ->  m
3578 // Add prefix                           m       ->  1_m
3579 // Remove prefix                        1_m     ->  m
3580 // Simultaneous add of prefixes         m       ->  3_2_1_m
3581 // Simultaneous removal of prefixes     3_2_1_m ->  m
3582 // Simultaneous add and remove          1_m     ->  2_m
3583 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
3584 //
3585 class TransferNativeFunctionRegistration {
3586  private:
3587   InstanceKlass* the_class;
3588   int prefix_count;
3589   char** prefixes;
3590 
3591   // Recursively search the binary tree of possibly prefixed method names.
3592   // Iteration could be used if all agents were well behaved. Full tree walk is
3593   // more resilent to agents not cleaning up intermediate methods.
3594   // Branch at each depth in the binary tree is:
3595   //    (1) without the prefix.
3596   //    (2) with the prefix.
3597   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3598   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3599                                      Symbol* signature) {
3600     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3601     if (name_symbol != NULL) {
3602       Method* method = the_class->lookup_method(name_symbol, signature);
3603       if (method != NULL) {
3604         // Even if prefixed, intermediate methods must exist.
3605         if (method->is_native()) {
3606           // Wahoo, we found a (possibly prefixed) version of the method, return it.
3607           return method;
3608         }
3609         if (depth < prefix_count) {
3610           // Try applying further prefixes (other than this one).
3611           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3612           if (method != NULL) {
3613             return method; // found
3614           }
3615 
3616           // Try adding this prefix to the method name and see if it matches
3617           // another method name.
3618           char* prefix = prefixes[depth];
3619           size_t prefix_len = strlen(prefix);
3620           size_t trial_len = name_len + prefix_len;
3621           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3622           strcpy(trial_name_str, prefix);
3623           strcat(trial_name_str, name_str);
3624           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3625                                             signature);
3626           if (method != NULL) {
3627             // If found along this branch, it was prefixed, mark as such
3628             method->set_is_prefixed_native();
3629             return method; // found
3630           }
3631         }
3632       }
3633     }
3634     return NULL;  // This whole branch bore nothing
3635   }
3636 
3637   // Return the method name with old prefixes stripped away.
3638   char* method_name_without_prefixes(Method* method) {
3639     Symbol* name = method->name();
3640     char* name_str = name->as_utf8();
3641 
3642     // Old prefixing may be defunct, strip prefixes, if any.
3643     for (int i = prefix_count-1; i >= 0; i--) {
3644       char* prefix = prefixes[i];
3645       size_t prefix_len = strlen(prefix);
3646       if (strncmp(prefix, name_str, prefix_len) == 0) {
3647         name_str += prefix_len;
3648       }
3649     }
3650     return name_str;
3651   }
3652 
3653   // Strip any prefixes off the old native method, then try to find a
3654   // (possibly prefixed) new native that matches it.
3655   Method* strip_and_search_for_new_native(Method* method) {
3656     ResourceMark rm;
3657     char* name_str = method_name_without_prefixes(method);
3658     return search_prefix_name_space(0, name_str, strlen(name_str),
3659                                     method->signature());
3660   }
3661 
3662  public:
3663 
3664   // Construct a native method transfer processor for this class.
3665   TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3666     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3667 
3668     the_class = _the_class;
3669     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3670   }
3671 
3672   // Attempt to transfer any of the old or deleted methods that are native
3673   void transfer_registrations(Method** old_methods, int methods_length) {
3674     for (int j = 0; j < methods_length; j++) {
3675       Method* old_method = old_methods[j];
3676 
3677       if (old_method->is_native() && old_method->has_native_function()) {
3678         Method* new_method = strip_and_search_for_new_native(old_method);
3679         if (new_method != NULL) {
3680           // Actually set the native function in the new method.
3681           // Redefine does not send events (except CFLH), certainly not this
3682           // behind the scenes re-registration.
3683           new_method->set_native_function(old_method->native_function(),
3684                               !Method::native_bind_event_is_interesting);
3685         }
3686       }
3687     }
3688   }
3689 };
3690 
3691 // Don't lose the association between a native method and its JNI function.
3692 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3693   TransferNativeFunctionRegistration transfer(the_class);
3694   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3695   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3696 }
3697 
3698 // Deoptimize all compiled code that depends on this class.
3699 //
3700 // If the can_redefine_classes capability is obtained in the onload
3701 // phase then the compiler has recorded all dependencies from startup.
3702 // In that case we need only deoptimize and throw away all compiled code
3703 // that depends on the class.
3704 //
3705 // If can_redefine_classes is obtained sometime after the onload
3706 // phase then the dependency information may be incomplete. In that case
3707 // the first call to RedefineClasses causes all compiled code to be
3708 // thrown away. As can_redefine_classes has been obtained then
3709 // all future compilations will record dependencies so second and
3710 // subsequent calls to RedefineClasses need only throw away code
3711 // that depends on the class.
3712 //
3713 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) {
3714   assert_locked_or_safepoint(Compile_lock);
3715 
3716   // All dependencies have been recorded from startup or this is a second or
3717   // subsequent use of RedefineClasses
3718   if (JvmtiExport::all_dependencies_are_recorded()) {
3719     CodeCache::flush_evol_dependents_on(ik);
3720   } else {
3721     CodeCache::mark_all_nmethods_for_deoptimization();
3722 
3723     ResourceMark rm(THREAD);
3724     DeoptimizationMarker dm;
3725 
3726     // Deoptimize all activations depending on marked nmethods
3727     Deoptimization::deoptimize_dependents();
3728 
3729     // Make the dependent methods not entrant
3730     CodeCache::make_marked_nmethods_not_entrant();
3731 
3732     // From now on we know that the dependency information is complete
3733     JvmtiExport::set_all_dependencies_are_recorded(true);
3734   }
3735 }
3736 
3737 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3738   Method* old_method;
3739   Method* new_method;
3740 
3741   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3742   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3743   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3744   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3745 
3746   _matching_methods_length = 0;
3747   _deleted_methods_length  = 0;
3748   _added_methods_length    = 0;
3749 
3750   int nj = 0;
3751   int oj = 0;
3752   while (true) {
3753     if (oj >= _old_methods->length()) {
3754       if (nj >= _new_methods->length()) {
3755         break; // we've looked at everything, done
3756       }
3757       // New method at the end
3758       new_method = _new_methods->at(nj);
3759       _added_methods[_added_methods_length++] = new_method;
3760       ++nj;
3761     } else if (nj >= _new_methods->length()) {
3762       // Old method, at the end, is deleted
3763       old_method = _old_methods->at(oj);
3764       _deleted_methods[_deleted_methods_length++] = old_method;
3765       ++oj;
3766     } else {
3767       old_method = _old_methods->at(oj);
3768       new_method = _new_methods->at(nj);
3769       if (old_method->name() == new_method->name()) {
3770         if (old_method->signature() == new_method->signature()) {
3771           _matching_old_methods[_matching_methods_length  ] = old_method;
3772           _matching_new_methods[_matching_methods_length++] = new_method;
3773           ++nj;
3774           ++oj;
3775         } else {
3776           // added overloaded have already been moved to the end,
3777           // so this is a deleted overloaded method
3778           _deleted_methods[_deleted_methods_length++] = old_method;
3779           ++oj;
3780         }
3781       } else { // names don't match
3782         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3783           // new method
3784           _added_methods[_added_methods_length++] = new_method;
3785           ++nj;
3786         } else {
3787           // deleted method
3788           _deleted_methods[_deleted_methods_length++] = old_method;
3789           ++oj;
3790         }
3791       }
3792     }
3793   }
3794   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3795   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3796 }
3797 
3798 
3799 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
3800                                           InstanceKlass* scratch_class) {
3801   // Swap annotation fields values
3802   Annotations* old_annotations = the_class->annotations();
3803   the_class->set_annotations(scratch_class->annotations());
3804   scratch_class->set_annotations(old_annotations);
3805 }
3806 
3807 
3808 // Install the redefinition of a class:
3809 //    - house keeping (flushing breakpoints and caches, deoptimizing
3810 //      dependent compiled code)
3811 //    - replacing parts in the_class with parts from scratch_class
3812 //    - adding a weak reference to track the obsolete but interesting
3813 //      parts of the_class
3814 //    - adjusting constant pool caches and vtables in other classes
3815 //      that refer to methods in the_class. These adjustments use the
3816 //      ClassLoaderDataGraph::classes_do() facility which only allows
3817 //      a helper method to be specified. The interesting parameters
3818 //      that we would like to pass to the helper method are saved in
3819 //      static global fields in the VM operation.
3820 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3821        InstanceKlass* scratch_class, TRAPS) {
3822 
3823   HandleMark hm(THREAD);   // make sure handles from this call are freed
3824 
3825   if (log_is_enabled(Info, redefine, class, timer)) {
3826     _timer_rsc_phase1.start();
3827   }
3828 
3829   InstanceKlass* the_class = get_ik(the_jclass);
3830 
3831   // Remove all breakpoints in methods of this class
3832   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3833   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
3834 
3835   // Deoptimize all compiled code that depends on this class
3836   flush_dependent_code(the_class, THREAD);
3837 
3838   _old_methods = the_class->methods();
3839   _new_methods = scratch_class->methods();
3840   _the_class = the_class;
3841   compute_added_deleted_matching_methods();
3842   update_jmethod_ids();
3843 
3844   _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
3845 
3846   // Attach new constant pool to the original klass. The original
3847   // klass still refers to the old constant pool (for now).
3848   scratch_class->constants()->set_pool_holder(the_class);
3849 
3850 #if 0
3851   // In theory, with constant pool merging in place we should be able
3852   // to save space by using the new, merged constant pool in place of
3853   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3854   // the klass version we are replacing now and any constant pool(s) in
3855   // previous versions of klass. Nice theory, doesn't work in practice.
3856   // When this code is enabled, even simple programs throw NullPointer
3857   // exceptions. I'm guessing that this is caused by some constant pool
3858   // cache difference between the new, merged constant pool and the
3859   // constant pool that was just being used by the klass. I'm keeping
3860   // this code around to archive the idea, but the code has to remain
3861   // disabled for now.
3862 
3863   // Attach each old method to the new constant pool. This can be
3864   // done here since we are past the bytecode verification and
3865   // constant pool optimization phases.
3866   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3867     Method* method = _old_methods->at(i);
3868     method->set_constants(scratch_class->constants());
3869   }
3870 
3871   // NOTE: this doesn't work because you can redefine the same class in two
3872   // threads, each getting their own constant pool data appended to the
3873   // original constant pool.  In order for the new methods to work when they
3874   // become old methods, they need to keep their updated copy of the constant pool.
3875 
3876   {
3877     // walk all previous versions of the klass
3878     InstanceKlass *ik = the_class;
3879     PreviousVersionWalker pvw(ik);
3880     do {
3881       ik = pvw.next_previous_version();
3882       if (ik != NULL) {
3883 
3884         // attach previous version of klass to the new constant pool
3885         ik->set_constants(scratch_class->constants());
3886 
3887         // Attach each method in the previous version of klass to the
3888         // new constant pool
3889         Array<Method*>* prev_methods = ik->methods();
3890         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3891           Method* method = prev_methods->at(i);
3892           method->set_constants(scratch_class->constants());
3893         }
3894       }
3895     } while (ik != NULL);
3896   }
3897 #endif
3898 
3899   // Replace methods and constantpool
3900   the_class->set_methods(_new_methods);
3901   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3902                                           // and to be able to undo operation easily.
3903 
3904   Array<int>* old_ordering = the_class->method_ordering();
3905   the_class->set_method_ordering(scratch_class->method_ordering());
3906   scratch_class->set_method_ordering(old_ordering);
3907 
3908   ConstantPool* old_constants = the_class->constants();
3909   the_class->set_constants(scratch_class->constants());
3910   scratch_class->set_constants(old_constants);  // See the previous comment.
3911 #if 0
3912   // We are swapping the guts of "the new class" with the guts of "the
3913   // class". Since the old constant pool has just been attached to "the
3914   // new class", it seems logical to set the pool holder in the old
3915   // constant pool also. However, doing this will change the observable
3916   // class hierarchy for any old methods that are still executing. A
3917   // method can query the identity of its "holder" and this query uses
3918   // the method's constant pool link to find the holder. The change in
3919   // holding class from "the class" to "the new class" can confuse
3920   // things.
3921   //
3922   // Setting the old constant pool's holder will also cause
3923   // verification done during vtable initialization below to fail.
3924   // During vtable initialization, the vtable's class is verified to be
3925   // a subtype of the method's holder. The vtable's class is "the
3926   // class" and the method's holder is gotten from the constant pool
3927   // link in the method itself. For "the class"'s directly implemented
3928   // methods, the method holder is "the class" itself (as gotten from
3929   // the new constant pool). The check works fine in this case. The
3930   // check also works fine for methods inherited from super classes.
3931   //
3932   // Miranda methods are a little more complicated. A miranda method is
3933   // provided by an interface when the class implementing the interface
3934   // does not provide its own method.  These interfaces are implemented
3935   // internally as an InstanceKlass. These special instanceKlasses
3936   // share the constant pool of the class that "implements" the
3937   // interface. By sharing the constant pool, the method holder of a
3938   // miranda method is the class that "implements" the interface. In a
3939   // non-redefine situation, the subtype check works fine. However, if
3940   // the old constant pool's pool holder is modified, then the check
3941   // fails because there is no class hierarchy relationship between the
3942   // vtable's class and "the new class".
3943 
3944   old_constants->set_pool_holder(scratch_class());
3945 #endif
3946 
3947   // track number of methods that are EMCP for add_previous_version() call below
3948   int emcp_method_count = check_methods_and_mark_as_obsolete();
3949   transfer_old_native_function_registrations(the_class);
3950 
3951   // The class file bytes from before any retransformable agents mucked
3952   // with them was cached on the scratch class, move to the_class.
3953   // Note: we still want to do this if nothing needed caching since it
3954   // should get cleared in the_class too.
3955   if (the_class->get_cached_class_file() == 0) {
3956     // the_class doesn't have a cache yet so copy it
3957     the_class->set_cached_class_file(scratch_class->get_cached_class_file());
3958   }
3959   else if (scratch_class->get_cached_class_file() !=
3960            the_class->get_cached_class_file()) {
3961     // The same class can be present twice in the scratch classes list or there
3962     // are multiple concurrent RetransformClasses calls on different threads.
3963     // In such cases we have to deallocate scratch_class cached_class_file.
3964     os::free(scratch_class->get_cached_class_file());
3965   }
3966 
3967   // NULL out in scratch class to not delete twice.  The class to be redefined
3968   // always owns these bytes.
3969   scratch_class->set_cached_class_file(NULL);
3970 
3971   // Replace inner_classes
3972   Array<u2>* old_inner_classes = the_class->inner_classes();
3973   the_class->set_inner_classes(scratch_class->inner_classes());
3974   scratch_class->set_inner_classes(old_inner_classes);
3975 
3976   // Initialize the vtable and interface table after
3977   // methods have been rewritten
3978   {
3979     ResourceMark rm(THREAD);
3980     // no exception should happen here since we explicitly
3981     // do not check loader constraints.
3982     // compare_and_normalize_class_versions has already checked:
3983     //  - classloaders unchanged, signatures unchanged
3984     //  - all instanceKlasses for redefined classes reused & contents updated
3985     the_class->vtable().initialize_vtable(false, THREAD);
3986     the_class->itable().initialize_itable(false, THREAD);
3987     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3988   }
3989 
3990   // Leave arrays of jmethodIDs and itable index cache unchanged
3991 
3992   // Copy the "source file name" attribute from new class version
3993   the_class->set_source_file_name_index(
3994     scratch_class->source_file_name_index());
3995 
3996   // Copy the "source debug extension" attribute from new class version
3997   the_class->set_source_debug_extension(
3998     scratch_class->source_debug_extension(),
3999     scratch_class->source_debug_extension() == NULL ? 0 :
4000     (int)strlen(scratch_class->source_debug_extension()));
4001 
4002   // Use of javac -g could be different in the old and the new
4003   if (scratch_class->access_flags().has_localvariable_table() !=
4004       the_class->access_flags().has_localvariable_table()) {
4005 
4006     AccessFlags flags = the_class->access_flags();
4007     if (scratch_class->access_flags().has_localvariable_table()) {
4008       flags.set_has_localvariable_table();
4009     } else {
4010       flags.clear_has_localvariable_table();
4011     }
4012     the_class->set_access_flags(flags);
4013   }
4014 
4015   swap_annotations(the_class, scratch_class);
4016 
4017   // Replace minor version number of class file
4018   u2 old_minor_version = the_class->minor_version();
4019   the_class->set_minor_version(scratch_class->minor_version());
4020   scratch_class->set_minor_version(old_minor_version);
4021 
4022   // Replace major version number of class file
4023   u2 old_major_version = the_class->major_version();
4024   the_class->set_major_version(scratch_class->major_version());
4025   scratch_class->set_major_version(old_major_version);
4026 
4027   // Replace CP indexes for class and name+type of enclosing method
4028   u2 old_class_idx  = the_class->enclosing_method_class_index();
4029   u2 old_method_idx = the_class->enclosing_method_method_index();
4030   the_class->set_enclosing_method_indices(
4031     scratch_class->enclosing_method_class_index(),
4032     scratch_class->enclosing_method_method_index());
4033   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4034 
4035   // Replace fingerprint data
4036   the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4037   the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4038 
4039   the_class->set_has_been_redefined();
4040 
4041   if (!the_class->should_be_initialized()) {
4042     // Class was already initialized, so AOT has only seen the original version.
4043     // We need to let AOT look at it again.
4044     AOTLoader::load_for_klass(the_class, THREAD);
4045   }
4046 
4047   // keep track of previous versions of this class
4048   the_class->add_previous_version(scratch_class, emcp_method_count);
4049 
4050   _timer_rsc_phase1.stop();
4051   if (log_is_enabled(Info, redefine, class, timer)) {
4052     _timer_rsc_phase2.start();
4053   }
4054 
4055   // Adjust constantpool caches and vtables for all classes
4056   // that reference methods of the evolved class.
4057   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4058   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4059 
4060   if (the_class->oop_map_cache() != NULL) {
4061     // Flush references to any obsolete methods from the oop map cache
4062     // so that obsolete methods are not pinned.
4063     the_class->oop_map_cache()->flush_obsolete_entries();
4064   }
4065 
4066   increment_class_counter((InstanceKlass *)the_class, THREAD);
4067   {
4068     ResourceMark rm(THREAD);
4069     // increment the classRedefinedCount field in the_class and in any
4070     // direct and indirect subclasses of the_class
4071     log_info(redefine, class, load)
4072       ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4073        the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4074     Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4075                              the_class->external_name(),
4076                              java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4077 
4078   }
4079   _timer_rsc_phase2.stop();
4080 } // end redefine_single_class()
4081 
4082 
4083 // Increment the classRedefinedCount field in the specific InstanceKlass
4084 // and in all direct and indirect subclasses.
4085 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4086   oop class_mirror = ik->java_mirror();
4087   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4088   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4089   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4090 
4091   if (class_oop != _the_class) {
4092     // _the_class count is printed at end of redefine_single_class()
4093     log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4094   }
4095 
4096   for (Klass *subk = ik->subklass(); subk != NULL;
4097        subk = subk->next_sibling()) {
4098     if (subk->is_instance_klass()) {
4099       // Only update instanceKlasses
4100       InstanceKlass *subik = InstanceKlass::cast(subk);
4101       // recursively do subclasses of the current subclass
4102       increment_class_counter(subik, THREAD);
4103     }
4104   }
4105 }
4106 
4107 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4108   bool no_old_methods = true;  // be optimistic
4109 
4110   // Both array and instance classes have vtables.
4111   // a vtable should never contain old or obsolete methods
4112   ResourceMark rm(_thread);
4113   if (k->vtable_length() > 0 &&
4114       !k->vtable().check_no_old_or_obsolete_entries()) {
4115     if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4116       log_trace(redefine, class, obsolete, metadata)
4117         ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4118          k->signature_name());
4119       k->vtable().dump_vtable();
4120     }
4121     no_old_methods = false;
4122   }
4123 
4124   if (k->is_instance_klass()) {
4125     HandleMark hm(_thread);
4126     InstanceKlass *ik = InstanceKlass::cast(k);
4127 
4128     // an itable should never contain old or obsolete methods
4129     if (ik->itable_length() > 0 &&
4130         !ik->itable().check_no_old_or_obsolete_entries()) {
4131       if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4132         log_trace(redefine, class, obsolete, metadata)
4133           ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4134            ik->signature_name());
4135         ik->itable().dump_itable();
4136       }
4137       no_old_methods = false;
4138     }
4139 
4140     // the constant pool cache should never contain non-deleted old or obsolete methods
4141     if (ik->constants() != NULL &&
4142         ik->constants()->cache() != NULL &&
4143         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4144       if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4145         log_trace(redefine, class, obsolete, metadata)
4146           ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4147            ik->signature_name());
4148         ik->constants()->cache()->dump_cache();
4149       }
4150       no_old_methods = false;
4151     }
4152   }
4153 
4154   // print and fail guarantee if old methods are found.
4155   if (!no_old_methods) {
4156     if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4157       dump_methods();
4158     } else {
4159       log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4160         "to see more info about the following guarantee() failure.");
4161     }
4162     guarantee(false, "OLD and/or OBSOLETE method(s) found");
4163   }
4164 }
4165 
4166 
4167 void VM_RedefineClasses::dump_methods() {
4168   int j;
4169   log_trace(redefine, class, dump)("_old_methods --");
4170   for (j = 0; j < _old_methods->length(); ++j) {
4171     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4172     Method* m = _old_methods->at(j);
4173     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4174     m->access_flags().print_on(&log_stream);
4175     log_stream.print(" --  ");
4176     m->print_name(&log_stream);
4177     log_stream.cr();
4178   }
4179   log_trace(redefine, class, dump)("_new_methods --");
4180   for (j = 0; j < _new_methods->length(); ++j) {
4181     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4182     Method* m = _new_methods->at(j);
4183     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4184     m->access_flags().print_on(&log_stream);
4185     log_stream.print(" --  ");
4186     m->print_name(&log_stream);
4187     log_stream.cr();
4188   }
4189   log_trace(redefine, class, dump)("_matching_methods --");
4190   for (j = 0; j < _matching_methods_length; ++j) {
4191     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4192     Method* m = _matching_old_methods[j];
4193     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4194     m->access_flags().print_on(&log_stream);
4195     log_stream.print(" --  ");
4196     m->print_name();
4197     log_stream.cr();
4198 
4199     m = _matching_new_methods[j];
4200     log_stream.print("      (%5d)  ", m->vtable_index());
4201     m->access_flags().print_on(&log_stream);
4202     log_stream.cr();
4203   }
4204   log_trace(redefine, class, dump)("_deleted_methods --");
4205   for (j = 0; j < _deleted_methods_length; ++j) {
4206     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4207     Method* m = _deleted_methods[j];
4208     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4209     m->access_flags().print_on(&log_stream);
4210     log_stream.print(" --  ");
4211     m->print_name(&log_stream);
4212     log_stream.cr();
4213   }
4214   log_trace(redefine, class, dump)("_added_methods --");
4215   for (j = 0; j < _added_methods_length; ++j) {
4216     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4217     Method* m = _added_methods[j];
4218     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4219     m->access_flags().print_on(&log_stream);
4220     log_stream.print(" --  ");
4221     m->print_name(&log_stream);
4222     log_stream.cr();
4223   }
4224 }
4225 
4226 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4227   VM_Operation::print_on_error(st);
4228   if (_the_class != NULL) {
4229     ResourceMark rm;
4230     st->print_cr(", redefining class %s", _the_class->external_name());
4231   }
4232 }