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/resolvedMethodTable.hpp"
  47 #include "prims/methodComparator.hpp"
  48 #include "runtime/deoptimization.hpp"
  49 #include "runtime/relocator.hpp"
  50 #include "utilities/bitMap.inline.hpp"
  51 #include "utilities/events.hpp"
  52 
  53 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
  54 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
  55 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
  56 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
  57 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
  58 Method**  VM_RedefineClasses::_added_methods        = NULL;
  59 int         VM_RedefineClasses::_matching_methods_length = 0;
  60 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  61 int         VM_RedefineClasses::_added_methods_length    = 0;
  62 Klass*      VM_RedefineClasses::_the_class = NULL;
  63 
  64 
  65 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  66                                        const jvmtiClassDefinition *class_defs,
  67                                        JvmtiClassLoadKind class_load_kind) {
  68   _class_count = class_count;
  69   _class_defs = class_defs;
  70   _class_load_kind = class_load_kind;
  71   _any_class_has_resolved_methods = false;
  72   _res = JVMTI_ERROR_NONE;
  73 }
  74 
  75 static inline InstanceKlass* get_ik(jclass def) {
  76   oop mirror = JNIHandles::resolve_non_null(def);
  77   return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
  78 }
  79 
  80 // If any of the classes are being redefined, wait
  81 // Parallel constant pool merging leads to indeterminate constant pools.
  82 void VM_RedefineClasses::lock_classes() {
  83   MutexLocker ml(RedefineClasses_lock);
  84   bool has_redefined;
  85   do {
  86     has_redefined = false;
  87     // Go through classes each time until none are being redefined.
  88     for (int i = 0; i < _class_count; i++) {
  89       if (get_ik(_class_defs[i].klass)->is_being_redefined()) {
  90         RedefineClasses_lock->wait();
  91         has_redefined = true;
  92         break;  // for loop
  93       }
  94     }
  95   } while (has_redefined);
  96   for (int i = 0; i < _class_count; i++) {
  97     get_ik(_class_defs[i].klass)->set_is_being_redefined(true);
  98   }
  99   RedefineClasses_lock->notify_all();
 100 }
 101 
 102 void VM_RedefineClasses::unlock_classes() {
 103   MutexLocker ml(RedefineClasses_lock);
 104   for (int i = 0; i < _class_count; i++) {
 105     assert(get_ik(_class_defs[i].klass)->is_being_redefined(),
 106            "should be being redefined to get here");
 107     get_ik(_class_defs[i].klass)->set_is_being_redefined(false);
 108   }
 109   RedefineClasses_lock->notify_all();
 110 }
 111 
 112 bool VM_RedefineClasses::doit_prologue() {
 113   if (_class_count == 0) {
 114     _res = JVMTI_ERROR_NONE;
 115     return false;
 116   }
 117   if (_class_defs == NULL) {
 118     _res = JVMTI_ERROR_NULL_POINTER;
 119     return false;
 120   }
 121   for (int i = 0; i < _class_count; i++) {
 122     if (_class_defs[i].klass == NULL) {
 123       _res = JVMTI_ERROR_INVALID_CLASS;
 124       return false;
 125     }
 126     if (_class_defs[i].class_byte_count == 0) {
 127       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
 128       return false;
 129     }
 130     if (_class_defs[i].class_bytes == NULL) {
 131       _res = JVMTI_ERROR_NULL_POINTER;
 132       return false;
 133     }
 134 
 135     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 136     // classes for primitives and arrays and vm anonymous classes cannot be redefined
 137     // check here so following code can assume these classes are InstanceKlass
 138     if (!is_modifiable_class(mirror)) {
 139       _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
 140       return false;
 141     }
 142   }
 143 
 144   // Start timer after all the sanity checks; not quite accurate, but
 145   // better than adding a bunch of stop() calls.
 146   if (log_is_enabled(Info, redefine, class, timer)) {
 147     _timer_vm_op_prologue.start();
 148   }
 149 
 150   lock_classes();
 151   // We first load new class versions in the prologue, because somewhere down the
 152   // call chain it is required that the current thread is a Java thread.
 153   _res = load_new_class_versions(Thread::current());
 154   if (_res != JVMTI_ERROR_NONE) {
 155     // free any successfully created classes, since none are redefined
 156     for (int i = 0; i < _class_count; i++) {
 157       if (_scratch_classes[i] != NULL) {
 158         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 159         // Free the memory for this class at class unloading time.  Not before
 160         // because CMS might think this is still live.
 161         InstanceKlass* ik = get_ik(_class_defs[i].klass);
 162         if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
 163           // Don't double-free cached_class_file copied from the original class if error.
 164           _scratch_classes[i]->set_cached_class_file(NULL);
 165         }
 166         cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
 167       }
 168     }
 169     // Free os::malloc allocated memory in load_new_class_version.
 170     os::free(_scratch_classes);
 171     _timer_vm_op_prologue.stop();
 172     unlock_classes();
 173     return false;
 174   }
 175 
 176   _timer_vm_op_prologue.stop();
 177   return true;
 178 }
 179 
 180 void VM_RedefineClasses::doit() {
 181   Thread *thread = Thread::current();
 182 
 183 #if INCLUDE_CDS
 184   if (UseSharedSpaces) {
 185     // Sharing is enabled so we remap the shared readonly space to
 186     // shared readwrite, private just in case we need to redefine
 187     // a shared class. We do the remap during the doit() phase of
 188     // the safepoint to be safer.
 189     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
 190       log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
 191       _res = JVMTI_ERROR_INTERNAL;
 192       return;
 193     }
 194   }
 195 #endif
 196 
 197   // Mark methods seen on stack and everywhere else so old methods are not
 198   // cleaned up if they're on the stack.
 199   MetadataOnStackMark md_on_stack(true);
 200   HandleMark hm(thread);   // make sure any handles created are deleted
 201                            // before the stack walk again.
 202 
 203   for (int i = 0; i < _class_count; i++) {
 204     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 205   }
 206 
 207   // Clean out MethodData pointing to old Method*
 208   // Have to do this after all classes are redefined and all methods that
 209   // are redefined are marked as old.
 210   MethodDataCleaner clean_weak_method_links;
 211   ClassLoaderDataGraph::classes_do(&clean_weak_method_links);
 212 
 213   // JSR-292 support
 214   if (_any_class_has_resolved_methods) {
 215     bool trace_name_printed = false;
 216     ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
 217   }
 218 
 219   // Disable any dependent concurrent compilations
 220   SystemDictionary::notice_modification();
 221 
 222   // Set flag indicating that some invariants are no longer true.
 223   // See jvmtiExport.hpp for detailed explanation.
 224   JvmtiExport::set_has_redefined_a_class();
 225 
 226   // check_class() is optionally called for product bits, but is
 227   // always called for non-product bits.
 228 #ifdef PRODUCT
 229   if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
 230 #endif
 231     log_trace(redefine, class, obsolete, metadata)("calling check_class");
 232     CheckClass check_class(thread);
 233     ClassLoaderDataGraph::classes_do(&check_class);
 234 #ifdef PRODUCT
 235   }
 236 #endif
 237 }
 238 
 239 void VM_RedefineClasses::doit_epilogue() {
 240   unlock_classes();
 241 
 242   // Free os::malloc allocated memory.
 243   os::free(_scratch_classes);
 244 
 245   // Reset the_class to null for error printing.
 246   _the_class = NULL;
 247 
 248   if (log_is_enabled(Info, redefine, class, timer)) {
 249     // Used to have separate timers for "doit" and "all", but the timer
 250     // overhead skewed the measurements.
 251     julong doit_time = _timer_rsc_phase1.milliseconds() +
 252                        _timer_rsc_phase2.milliseconds();
 253     julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 254 
 255     log_info(redefine, class, timer)
 256       ("vm_op: all=" JULONG_FORMAT "  prologue=" JULONG_FORMAT "  doit=" JULONG_FORMAT,
 257        all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
 258     log_info(redefine, class, timer)
 259       ("redefine_single_class: phase1=" JULONG_FORMAT "  phase2=" JULONG_FORMAT,
 260        (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
 261   }
 262 }
 263 
 264 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 265   // classes for primitives cannot be redefined
 266   if (java_lang_Class::is_primitive(klass_mirror)) {
 267     return false;
 268   }
 269   Klass* k = java_lang_Class::as_Klass(klass_mirror);
 270   // classes for arrays cannot be redefined
 271   if (k == NULL || !k->is_instance_klass()) {
 272     return false;
 273   }
 274 
 275   // Cannot redefine or retransform an anonymous class.
 276   if (InstanceKlass::cast(k)->is_anonymous()) {
 277     return false;
 278   }
 279   return true;
 280 }
 281 
 282 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 283 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 284 // direct CP entries, there is just the current entry to append. For
 285 // indirect and double-indirect CP entries, there are zero or more
 286 // referenced CP entries along with the current entry to append.
 287 // Indirect and double-indirect CP entries are handled by recursive
 288 // calls to append_entry() as needed. The referenced CP entries are
 289 // always appended to *merge_cp_p before the referee CP entry. These
 290 // referenced CP entries may already exist in *merge_cp_p in which case
 291 // there is nothing extra to append and only the current entry is
 292 // appended.
 293 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
 294        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 295        TRAPS) {
 296 
 297   // append is different depending on entry tag type
 298   switch (scratch_cp->tag_at(scratch_i).value()) {
 299 
 300     // The old verifier is implemented outside the VM. It loads classes,
 301     // but does not resolve constant pool entries directly so we never
 302     // see Class entries here with the old verifier. Similarly the old
 303     // verifier does not like Class entries in the input constant pool.
 304     // The split-verifier is implemented in the VM so it can optionally
 305     // and directly resolve constant pool entries to load classes. The
 306     // split-verifier can accept either Class entries or UnresolvedClass
 307     // entries in the input constant pool. We revert the appended copy
 308     // back to UnresolvedClass so that either verifier will be happy
 309     // with the constant pool entry.
 310     //
 311     // this is an indirect CP entry so it needs special handling
 312     case JVM_CONSTANT_Class:
 313     case JVM_CONSTANT_UnresolvedClass:
 314     {
 315       int name_i = scratch_cp->klass_name_index_at(scratch_i);
 316       int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
 317                                                      merge_cp_length_p, THREAD);
 318 
 319       if (new_name_i != name_i) {
 320         log_trace(redefine, class, constantpool)
 321           ("Class entry@%d name_index change: %d to %d",
 322            *merge_cp_length_p, name_i, new_name_i);
 323       }
 324 
 325       (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
 326       if (scratch_i != *merge_cp_length_p) {
 327         // The new entry in *merge_cp_p is at a different index than
 328         // the new entry in scratch_cp so we need to map the index values.
 329         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 330       }
 331       (*merge_cp_length_p)++;
 332     } break;
 333 
 334     // these are direct CP entries so they can be directly appended,
 335     // but double and long take two constant pool entries
 336     case JVM_CONSTANT_Double:  // fall through
 337     case JVM_CONSTANT_Long:
 338     {
 339       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 340         THREAD);
 341 
 342       if (scratch_i != *merge_cp_length_p) {
 343         // The new entry in *merge_cp_p is at a different index than
 344         // the new entry in scratch_cp so we need to map the index values.
 345         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 346       }
 347       (*merge_cp_length_p) += 2;
 348     } break;
 349 
 350     // these are direct CP entries so they can be directly appended
 351     case JVM_CONSTANT_Float:   // fall through
 352     case JVM_CONSTANT_Integer: // fall through
 353     case JVM_CONSTANT_Utf8:    // fall through
 354 
 355     // This was an indirect CP entry, but it has been changed into
 356     // Symbol*s so this entry can be directly appended.
 357     case JVM_CONSTANT_String:      // fall through
 358     {
 359       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 360         THREAD);
 361 
 362       if (scratch_i != *merge_cp_length_p) {
 363         // The new entry in *merge_cp_p is at a different index than
 364         // the new entry in scratch_cp so we need to map the index values.
 365         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 366       }
 367       (*merge_cp_length_p)++;
 368     } break;
 369 
 370     // this is an indirect CP entry so it needs special handling
 371     case JVM_CONSTANT_NameAndType:
 372     {
 373       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 374       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
 375                                                          merge_cp_length_p, THREAD);
 376 
 377       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 378       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
 379                                                               merge_cp_p, merge_cp_length_p,
 380                                                               THREAD);
 381 
 382       // If the referenced entries already exist in *merge_cp_p, then
 383       // both new_name_ref_i and new_signature_ref_i will both be 0.
 384       // In that case, all we are appending is the current entry.
 385       if (new_name_ref_i != name_ref_i) {
 386         log_trace(redefine, class, constantpool)
 387           ("NameAndType entry@%d name_ref_index change: %d to %d",
 388            *merge_cp_length_p, name_ref_i, new_name_ref_i);
 389       }
 390       if (new_signature_ref_i != signature_ref_i) {
 391         log_trace(redefine, class, constantpool)
 392           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 393            *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
 394       }
 395 
 396       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 397         new_name_ref_i, new_signature_ref_i);
 398       if (scratch_i != *merge_cp_length_p) {
 399         // The new entry in *merge_cp_p is at a different index than
 400         // the new entry in scratch_cp so we need to map the index values.
 401         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 402       }
 403       (*merge_cp_length_p)++;
 404     } break;
 405 
 406     // this is a double-indirect CP entry so it needs special handling
 407     case JVM_CONSTANT_Fieldref:           // fall through
 408     case JVM_CONSTANT_InterfaceMethodref: // fall through
 409     case JVM_CONSTANT_Methodref:
 410     {
 411       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 412       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
 413                                                           merge_cp_p, merge_cp_length_p, THREAD);
 414 
 415       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 416       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
 417                                                           merge_cp_p, merge_cp_length_p, THREAD);
 418 
 419       const char *entry_name = NULL;
 420       switch (scratch_cp->tag_at(scratch_i).value()) {
 421       case JVM_CONSTANT_Fieldref:
 422         entry_name = "Fieldref";
 423         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 424           new_name_and_type_ref_i);
 425         break;
 426       case JVM_CONSTANT_InterfaceMethodref:
 427         entry_name = "IFMethodref";
 428         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 429           new_klass_ref_i, new_name_and_type_ref_i);
 430         break;
 431       case JVM_CONSTANT_Methodref:
 432         entry_name = "Methodref";
 433         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 434           new_name_and_type_ref_i);
 435         break;
 436       default:
 437         guarantee(false, "bad switch");
 438         break;
 439       }
 440 
 441       if (klass_ref_i != new_klass_ref_i) {
 442         log_trace(redefine, class, constantpool)
 443           ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
 444       }
 445       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 446         log_trace(redefine, class, constantpool)
 447           ("%s entry@%d name_and_type_index changed: %d to %d",
 448            entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
 449       }
 450 
 451       if (scratch_i != *merge_cp_length_p) {
 452         // The new entry in *merge_cp_p is at a different index than
 453         // the new entry in scratch_cp so we need to map the index values.
 454         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 455       }
 456       (*merge_cp_length_p)++;
 457     } break;
 458 
 459     // this is an indirect CP entry so it needs special handling
 460     case JVM_CONSTANT_MethodType:
 461     {
 462       int ref_i = scratch_cp->method_type_index_at(scratch_i);
 463       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 464                                                     merge_cp_length_p, THREAD);
 465       if (new_ref_i != ref_i) {
 466         log_trace(redefine, class, constantpool)
 467           ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
 468       }
 469       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
 470       if (scratch_i != *merge_cp_length_p) {
 471         // The new entry in *merge_cp_p is at a different index than
 472         // the new entry in scratch_cp so we need to map the index values.
 473         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 474       }
 475       (*merge_cp_length_p)++;
 476     } break;
 477 
 478     // this is an indirect CP entry so it needs special handling
 479     case JVM_CONSTANT_MethodHandle:
 480     {
 481       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
 482       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
 483       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 484                                                     merge_cp_length_p, THREAD);
 485       if (new_ref_i != ref_i) {
 486         log_trace(redefine, class, constantpool)
 487           ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
 488       }
 489       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
 490       if (scratch_i != *merge_cp_length_p) {
 491         // The new entry in *merge_cp_p is at a different index than
 492         // the new entry in scratch_cp so we need to map the index values.
 493         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 494       }
 495       (*merge_cp_length_p)++;
 496     } break;
 497 
 498     // this is an indirect CP entry so it needs special handling
 499     case JVM_CONSTANT_InvokeDynamic:
 500     {
 501       // Index of the bootstrap specifier in the operands array
 502       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
 503       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
 504                                             merge_cp_length_p, THREAD);
 505       // The bootstrap method NameAndType_info index
 506       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
 507       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 508                                                     merge_cp_length_p, THREAD);
 509       if (new_bs_i != old_bs_i) {
 510         log_trace(redefine, class, constantpool)
 511           ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
 512            *merge_cp_length_p, old_bs_i, new_bs_i);
 513       }
 514       if (new_ref_i != old_ref_i) {
 515         log_trace(redefine, class, constantpool)
 516           ("InvokeDynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
 517       }
 518 
 519       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
 520       if (scratch_i != *merge_cp_length_p) {
 521         // The new entry in *merge_cp_p is at a different index than
 522         // the new entry in scratch_cp so we need to map the index values.
 523         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 524       }
 525       (*merge_cp_length_p)++;
 526     } break;
 527 
 528     // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
 529     // ClassIndex
 530     case JVM_CONSTANT_ClassIndex: // fall through
 531 
 532     // Invalid is used as the tag for the second constant pool entry
 533     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 534     // not be seen by itself.
 535     case JVM_CONSTANT_Invalid: // fall through
 536 
 537     // At this stage, String could be here, but not StringIndex
 538     case JVM_CONSTANT_StringIndex: // fall through
 539 
 540     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 541     // here
 542     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 543 
 544     default:
 545     {
 546       // leave a breadcrumb
 547       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 548       ShouldNotReachHere();
 549     } break;
 550   } // end switch tag value
 551 } // end append_entry()
 552 
 553 
 554 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
 555       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 556 
 557   int new_ref_i = ref_i;
 558   bool match = (ref_i < *merge_cp_length_p) &&
 559                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
 560 
 561   if (!match) {
 562     // forward reference in *merge_cp_p or not a direct match
 563     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
 564     if (found_i != 0) {
 565       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
 566       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
 567       new_ref_i = found_i;
 568       map_index(scratch_cp, ref_i, found_i);
 569     } else {
 570       // no match found so we have to append this entry to *merge_cp_p
 571       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
 572       // The above call to append_entry() can only append one entry
 573       // so the post call query of *merge_cp_length_p is only for
 574       // the sake of consistency.
 575       new_ref_i = *merge_cp_length_p - 1;
 576     }
 577   }
 578 
 579   return new_ref_i;
 580 } // end find_or_append_indirect_entry()
 581 
 582 
 583 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
 584 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
 585 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
 586 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
 587        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 588 
 589   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
 590   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 591                                                 merge_cp_length_p, THREAD);
 592   if (new_ref_i != old_ref_i) {
 593     log_trace(redefine, class, constantpool)
 594       ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
 595   }
 596 
 597   Array<u2>* merge_ops = (*merge_cp_p)->operands();
 598   int new_bs_i = _operands_cur_length;
 599   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
 600   // However, the operand_offset_at(0) was set in the extend_operands() call.
 601   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
 602                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
 603   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
 604 
 605   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
 606   merge_ops->at_put(new_base++, new_ref_i);
 607   merge_ops->at_put(new_base++, argc);
 608 
 609   for (int i = 0; i < argc; i++) {
 610     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
 611     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
 612                                                       merge_cp_length_p, THREAD);
 613     merge_ops->at_put(new_base++, new_arg_ref_i);
 614     if (new_arg_ref_i != old_arg_ref_i) {
 615       log_trace(redefine, class, constantpool)
 616         ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
 617          _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
 618     }
 619   }
 620   if (old_bs_i != _operands_cur_length) {
 621     // The bootstrap specifier in *merge_cp_p is at a different index than
 622     // that in scratch_cp so we need to map the index values.
 623     map_operand_index(old_bs_i, new_bs_i);
 624   }
 625   _operands_cur_length++;
 626 } // end append_operand()
 627 
 628 
 629 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
 630       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 631 
 632   int new_bs_i = old_bs_i; // bootstrap specifier index
 633   bool match = (old_bs_i < _operands_cur_length) &&
 634                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
 635 
 636   if (!match) {
 637     // forward reference in *merge_cp_p or not a direct match
 638     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
 639                                                     _operands_cur_length, THREAD);
 640     if (found_i != -1) {
 641       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
 642       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
 643       new_bs_i = found_i;
 644       map_operand_index(old_bs_i, found_i);
 645     } else {
 646       // no match found so we have to append this bootstrap specifier to *merge_cp_p
 647       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
 648       new_bs_i = _operands_cur_length - 1;
 649     }
 650   }
 651   return new_bs_i;
 652 } // end find_or_append_operand()
 653 
 654 
 655 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
 656   if (merge_cp->operands() == NULL) {
 657     return;
 658   }
 659   // Shrink the merge_cp operands
 660   merge_cp->shrink_operands(_operands_cur_length, CHECK);
 661 
 662   if (log_is_enabled(Trace, redefine, class, constantpool)) {
 663     // don't want to loop unless we are tracing
 664     int count = 0;
 665     for (int i = 1; i < _operands_index_map_p->length(); i++) {
 666       int value = _operands_index_map_p->at(i);
 667       if (value != -1) {
 668         log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
 669         count++;
 670       }
 671     }
 672   }
 673   // Clean-up
 674   _operands_index_map_p = NULL;
 675   _operands_cur_length = 0;
 676   _operands_index_map_count = 0;
 677 } // end finalize_operands_merge()
 678 
 679 
 680 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 681              InstanceKlass* the_class,
 682              InstanceKlass* scratch_class) {
 683   int i;
 684 
 685   // Check superclasses, or rather their names, since superclasses themselves can be
 686   // requested to replace.
 687   // Check for NULL superclass first since this might be java.lang.Object
 688   if (the_class->super() != scratch_class->super() &&
 689       (the_class->super() == NULL || scratch_class->super() == NULL ||
 690        the_class->super()->name() !=
 691        scratch_class->super()->name())) {
 692     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 693   }
 694 
 695   // Check if the number, names and order of directly implemented interfaces are the same.
 696   // I think in principle we should just check if the sets of names of directly implemented
 697   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 698   // .java file, also changes in .class file) should not matter. However, comparing sets is
 699   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 700   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 701   // rely on it somewhere.
 702   Array<Klass*>* k_interfaces = the_class->local_interfaces();
 703   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
 704   int n_intfs = k_interfaces->length();
 705   if (n_intfs != k_new_interfaces->length()) {
 706     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 707   }
 708   for (i = 0; i < n_intfs; i++) {
 709     if (k_interfaces->at(i)->name() !=
 710         k_new_interfaces->at(i)->name()) {
 711       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 712     }
 713   }
 714 
 715   // Check whether class is in the error init state.
 716   if (the_class->is_in_error_state()) {
 717     // TBD #5057930: special error code is needed in 1.6
 718     return JVMTI_ERROR_INVALID_CLASS;
 719   }
 720 
 721   // Check whether class modifiers are the same.
 722   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 723   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 724   if (old_flags != new_flags) {
 725     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 726   }
 727 
 728   // Check if the number, names, types and order of fields declared in these classes
 729   // are the same.
 730   JavaFieldStream old_fs(the_class);
 731   JavaFieldStream new_fs(scratch_class);
 732   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 733     // access
 734     old_flags = old_fs.access_flags().as_short();
 735     new_flags = new_fs.access_flags().as_short();
 736     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 737       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 738     }
 739     // offset
 740     if (old_fs.offset() != new_fs.offset()) {
 741       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 742     }
 743     // name and signature
 744     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 745     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 746     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 747     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 748     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 749       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 750     }
 751   }
 752 
 753   // If both streams aren't done then we have a differing number of
 754   // fields.
 755   if (!old_fs.done() || !new_fs.done()) {
 756     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 757   }
 758 
 759   // Do a parallel walk through the old and new methods. Detect
 760   // cases where they match (exist in both), have been added in
 761   // the new methods, or have been deleted (exist only in the
 762   // old methods).  The class file parser places methods in order
 763   // by method name, but does not order overloaded methods by
 764   // signature.  In order to determine what fate befell the methods,
 765   // this code places the overloaded new methods that have matching
 766   // old methods in the same order as the old methods and places
 767   // new overloaded methods at the end of overloaded methods of
 768   // that name. The code for this order normalization is adapted
 769   // from the algorithm used in InstanceKlass::find_method().
 770   // Since we are swapping out of order entries as we find them,
 771   // we only have to search forward through the overloaded methods.
 772   // Methods which are added and have the same name as an existing
 773   // method (but different signature) will be put at the end of
 774   // the methods with that name, and the name mismatch code will
 775   // handle them.
 776   Array<Method*>* k_old_methods(the_class->methods());
 777   Array<Method*>* k_new_methods(scratch_class->methods());
 778   int n_old_methods = k_old_methods->length();
 779   int n_new_methods = k_new_methods->length();
 780   Thread* thread = Thread::current();
 781 
 782   int ni = 0;
 783   int oi = 0;
 784   while (true) {
 785     Method* k_old_method;
 786     Method* k_new_method;
 787     enum { matched, added, deleted, undetermined } method_was = undetermined;
 788 
 789     if (oi >= n_old_methods) {
 790       if (ni >= n_new_methods) {
 791         break; // we've looked at everything, done
 792       }
 793       // New method at the end
 794       k_new_method = k_new_methods->at(ni);
 795       method_was = added;
 796     } else if (ni >= n_new_methods) {
 797       // Old method, at the end, is deleted
 798       k_old_method = k_old_methods->at(oi);
 799       method_was = deleted;
 800     } else {
 801       // There are more methods in both the old and new lists
 802       k_old_method = k_old_methods->at(oi);
 803       k_new_method = k_new_methods->at(ni);
 804       if (k_old_method->name() != k_new_method->name()) {
 805         // Methods are sorted by method name, so a mismatch means added
 806         // or deleted
 807         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 808           method_was = added;
 809         } else {
 810           method_was = deleted;
 811         }
 812       } else if (k_old_method->signature() == k_new_method->signature()) {
 813         // Both the name and signature match
 814         method_was = matched;
 815       } else {
 816         // The name matches, but the signature doesn't, which means we have to
 817         // search forward through the new overloaded methods.
 818         int nj;  // outside the loop for post-loop check
 819         for (nj = ni + 1; nj < n_new_methods; nj++) {
 820           Method* m = k_new_methods->at(nj);
 821           if (k_old_method->name() != m->name()) {
 822             // reached another method name so no more overloaded methods
 823             method_was = deleted;
 824             break;
 825           }
 826           if (k_old_method->signature() == m->signature()) {
 827             // found a match so swap the methods
 828             k_new_methods->at_put(ni, m);
 829             k_new_methods->at_put(nj, k_new_method);
 830             k_new_method = m;
 831             method_was = matched;
 832             break;
 833           }
 834         }
 835 
 836         if (nj >= n_new_methods) {
 837           // reached the end without a match; so method was deleted
 838           method_was = deleted;
 839         }
 840       }
 841     }
 842 
 843     switch (method_was) {
 844     case matched:
 845       // methods match, be sure modifiers do too
 846       old_flags = (jushort) k_old_method->access_flags().get_flags();
 847       new_flags = (jushort) k_new_method->access_flags().get_flags();
 848       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 849         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 850       }
 851       {
 852         u2 new_num = k_new_method->method_idnum();
 853         u2 old_num = k_old_method->method_idnum();
 854         if (new_num != old_num) {
 855           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
 856           if (idnum_owner != NULL) {
 857             // There is already a method assigned this idnum -- switch them
 858             // Take current and original idnum from the new_method
 859             idnum_owner->set_method_idnum(new_num);
 860             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 861           }
 862           // Take current and original idnum from the old_method
 863           k_new_method->set_method_idnum(old_num);
 864           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
 865           if (thread->has_pending_exception()) {
 866             return JVMTI_ERROR_OUT_OF_MEMORY;
 867           }
 868         }
 869       }
 870       log_trace(redefine, class, normalize)
 871         ("Method matched: new: %s [%d] == old: %s [%d]",
 872          k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
 873       // advance to next pair of methods
 874       ++oi;
 875       ++ni;
 876       break;
 877     case added:
 878       // method added, see if it is OK
 879       new_flags = (jushort) k_new_method->access_flags().get_flags();
 880       if ((new_flags & JVM_ACC_PRIVATE) == 0
 881            // hack: private should be treated as final, but alas
 882           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 883          ) {
 884         // new methods must be private
 885         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 886       }
 887       {
 888         u2 num = the_class->next_method_idnum();
 889         if (num == ConstMethod::UNSET_IDNUM) {
 890           // cannot add any more methods
 891           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 892         }
 893         u2 new_num = k_new_method->method_idnum();
 894         Method* idnum_owner = scratch_class->method_with_idnum(num);
 895         if (idnum_owner != NULL) {
 896           // There is already a method assigned this idnum -- switch them
 897           // Take current and original idnum from the new_method
 898           idnum_owner->set_method_idnum(new_num);
 899           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 900         }
 901         k_new_method->set_method_idnum(num);
 902         k_new_method->set_orig_method_idnum(num);
 903         if (thread->has_pending_exception()) {
 904           return JVMTI_ERROR_OUT_OF_MEMORY;
 905         }
 906       }
 907       log_trace(redefine, class, normalize)
 908         ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
 909       ++ni; // advance to next new method
 910       break;
 911     case deleted:
 912       // method deleted, see if it is OK
 913       old_flags = (jushort) k_old_method->access_flags().get_flags();
 914       if ((old_flags & JVM_ACC_PRIVATE) == 0
 915            // hack: private should be treated as final, but alas
 916           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 917          ) {
 918         // deleted methods must be private
 919         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 920       }
 921       log_trace(redefine, class, normalize)
 922         ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
 923       ++oi; // advance to next old method
 924       break;
 925     default:
 926       ShouldNotReachHere();
 927     }
 928   }
 929 
 930   return JVMTI_ERROR_NONE;
 931 }
 932 
 933 
 934 // Find new constant pool index value for old constant pool index value
 935 // by seaching the index map. Returns zero (0) if there is no mapped
 936 // value for the old constant pool index.
 937 int VM_RedefineClasses::find_new_index(int old_index) {
 938   if (_index_map_count == 0) {
 939     // map is empty so nothing can be found
 940     return 0;
 941   }
 942 
 943   if (old_index < 1 || old_index >= _index_map_p->length()) {
 944     // The old_index is out of range so it is not mapped. This should
 945     // not happen in regular constant pool merging use, but it can
 946     // happen if a corrupt annotation is processed.
 947     return 0;
 948   }
 949 
 950   int value = _index_map_p->at(old_index);
 951   if (value == -1) {
 952     // the old_index is not mapped
 953     return 0;
 954   }
 955 
 956   return value;
 957 } // end find_new_index()
 958 
 959 
 960 // Find new bootstrap specifier index value for old bootstrap specifier index
 961 // value by seaching the index map. Returns unused index (-1) if there is
 962 // no mapped value for the old bootstrap specifier index.
 963 int VM_RedefineClasses::find_new_operand_index(int old_index) {
 964   if (_operands_index_map_count == 0) {
 965     // map is empty so nothing can be found
 966     return -1;
 967   }
 968 
 969   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
 970     // The old_index is out of range so it is not mapped.
 971     // This should not happen in regular constant pool merging use.
 972     return -1;
 973   }
 974 
 975   int value = _operands_index_map_p->at(old_index);
 976   if (value == -1) {
 977     // the old_index is not mapped
 978     return -1;
 979   }
 980 
 981   return value;
 982 } // end find_new_operand_index()
 983 
 984 
 985 // Returns true if the current mismatch is due to a resolved/unresolved
 986 // class pair. Otherwise, returns false.
 987 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
 988        int index1, const constantPoolHandle& cp2, int index2) {
 989 
 990   jbyte t1 = cp1->tag_at(index1).value();
 991   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 992     return false;  // wrong entry type; not our special case
 993   }
 994 
 995   jbyte t2 = cp2->tag_at(index2).value();
 996   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 997     return false;  // wrong entry type; not our special case
 998   }
 999 
1000   if (t1 == t2) {
1001     return false;  // not a mismatch; not our special case
1002   }
1003 
1004   char *s1 = cp1->klass_name_at(index1)->as_C_string();
1005   char *s2 = cp2->klass_name_at(index2)->as_C_string();
1006   if (strcmp(s1, s2) != 0) {
1007     return false;  // strings don't match; not our special case
1008   }
1009 
1010   return true;  // made it through the gauntlet; this is our special case
1011 } // end is_unresolved_class_mismatch()
1012 
1013 
1014 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1015 
1016   // For consistency allocate memory using os::malloc wrapper.
1017   _scratch_classes = (InstanceKlass**)
1018     os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1019   if (_scratch_classes == NULL) {
1020     return JVMTI_ERROR_OUT_OF_MEMORY;
1021   }
1022   // Zero initialize the _scratch_classes array.
1023   for (int i = 0; i < _class_count; i++) {
1024     _scratch_classes[i] = NULL;
1025   }
1026 
1027   ResourceMark rm(THREAD);
1028 
1029   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1030   // state can only be NULL if the current thread is exiting which
1031   // should not happen since we're trying to do a RedefineClasses
1032   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1033   for (int i = 0; i < _class_count; i++) {
1034     // Create HandleMark so that any handles created while loading new class
1035     // versions are deleted. Constant pools are deallocated while merging
1036     // constant pools
1037     HandleMark hm(THREAD);
1038     InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1039     Symbol*  the_class_sym = the_class->name();
1040 
1041     log_debug(redefine, class, load)
1042       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1043        the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1044 
1045     ClassFileStream st((u1*)_class_defs[i].class_bytes,
1046                        _class_defs[i].class_byte_count,
1047                        "__VM_RedefineClasses__",
1048                        ClassFileStream::verify);
1049 
1050     // Parse the stream.
1051     Handle the_class_loader(THREAD, the_class->class_loader());
1052     Handle protection_domain(THREAD, the_class->protection_domain());
1053     // Set redefined class handle in JvmtiThreadState class.
1054     // This redefined class is sent to agent event handler for class file
1055     // load hook event.
1056     state->set_class_being_redefined(the_class, _class_load_kind);
1057 
1058     InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1059                                                       the_class_sym,
1060                                                       the_class_loader,
1061                                                       protection_domain,
1062                                                       &st,
1063                                                       THREAD);
1064     // Clear class_being_redefined just to be sure.
1065     state->clear_class_being_redefined();
1066 
1067     // TODO: if this is retransform, and nothing changed we can skip it
1068 
1069     // Need to clean up allocated InstanceKlass if there's an error so assign
1070     // the result here. Caller deallocates all the scratch classes in case of
1071     // an error.
1072     _scratch_classes[i] = scratch_class;
1073 
1074     if (HAS_PENDING_EXCEPTION) {
1075       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1076       log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1077       CLEAR_PENDING_EXCEPTION;
1078 
1079       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1080         return JVMTI_ERROR_UNSUPPORTED_VERSION;
1081       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1082         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1083       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1084         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1085       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1086         // The message will be "XXX (wrong name: YYY)"
1087         return JVMTI_ERROR_NAMES_DONT_MATCH;
1088       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1089         return JVMTI_ERROR_OUT_OF_MEMORY;
1090       } else {  // Just in case more exceptions can be thrown..
1091         return JVMTI_ERROR_FAILS_VERIFICATION;
1092       }
1093     }
1094 
1095     // Ensure class is linked before redefine
1096     if (!the_class->is_linked()) {
1097       the_class->link_class(THREAD);
1098       if (HAS_PENDING_EXCEPTION) {
1099         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1100         log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1101         CLEAR_PENDING_EXCEPTION;
1102         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1103           return JVMTI_ERROR_OUT_OF_MEMORY;
1104         } else {
1105           return JVMTI_ERROR_INTERNAL;
1106         }
1107       }
1108     }
1109 
1110     // Do the validity checks in compare_and_normalize_class_versions()
1111     // before verifying the byte codes. By doing these checks first, we
1112     // limit the number of functions that require redirection from
1113     // the_class to scratch_class. In particular, we don't have to
1114     // modify JNI GetSuperclass() and thus won't change its performance.
1115     jvmtiError res = compare_and_normalize_class_versions(the_class,
1116                        scratch_class);
1117     if (res != JVMTI_ERROR_NONE) {
1118       return res;
1119     }
1120 
1121     // verify what the caller passed us
1122     {
1123       // The bug 6214132 caused the verification to fail.
1124       // Information about the_class and scratch_class is temporarily
1125       // recorded into jvmtiThreadState. This data is used to redirect
1126       // the_class to scratch_class in the JVM_* functions called by the
1127       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1128       // description.
1129       RedefineVerifyMark rvm(the_class, scratch_class, state);
1130       Verifier::verify(
1131         scratch_class, Verifier::ThrowException, true, THREAD);
1132     }
1133 
1134     if (HAS_PENDING_EXCEPTION) {
1135       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1136       log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1137       CLEAR_PENDING_EXCEPTION;
1138       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1139         return JVMTI_ERROR_OUT_OF_MEMORY;
1140       } else {
1141         // tell the caller the bytecodes are bad
1142         return JVMTI_ERROR_FAILS_VERIFICATION;
1143       }
1144     }
1145 
1146     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1147     if (HAS_PENDING_EXCEPTION) {
1148       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1149       log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1150       CLEAR_PENDING_EXCEPTION;
1151       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1152         return JVMTI_ERROR_OUT_OF_MEMORY;
1153       } else {
1154         return JVMTI_ERROR_INTERNAL;
1155       }
1156     }
1157 
1158     if (VerifyMergedCPBytecodes) {
1159       // verify what we have done during constant pool merging
1160       {
1161         RedefineVerifyMark rvm(the_class, scratch_class, state);
1162         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1163       }
1164 
1165       if (HAS_PENDING_EXCEPTION) {
1166         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1167         log_info(redefine, class, load, exceptions)
1168           ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1169         CLEAR_PENDING_EXCEPTION;
1170         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1171           return JVMTI_ERROR_OUT_OF_MEMORY;
1172         } else {
1173           // tell the caller that constant pool merging screwed up
1174           return JVMTI_ERROR_INTERNAL;
1175         }
1176       }
1177     }
1178 
1179     Rewriter::rewrite(scratch_class, THREAD);
1180     if (!HAS_PENDING_EXCEPTION) {
1181       scratch_class->link_methods(THREAD);
1182     }
1183     if (HAS_PENDING_EXCEPTION) {
1184       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1185       log_info(redefine, class, load, exceptions)
1186         ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1187       CLEAR_PENDING_EXCEPTION;
1188       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1189         return JVMTI_ERROR_OUT_OF_MEMORY;
1190       } else {
1191         return JVMTI_ERROR_INTERNAL;
1192       }
1193     }
1194 
1195     log_debug(redefine, class, load)
1196       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1197   }
1198 
1199   return JVMTI_ERROR_NONE;
1200 }
1201 
1202 
1203 // Map old_index to new_index as needed. scratch_cp is only needed
1204 // for log calls.
1205 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1206        int old_index, int new_index) {
1207   if (find_new_index(old_index) != 0) {
1208     // old_index is already mapped
1209     return;
1210   }
1211 
1212   if (old_index == new_index) {
1213     // no mapping is needed
1214     return;
1215   }
1216 
1217   _index_map_p->at_put(old_index, new_index);
1218   _index_map_count++;
1219 
1220   log_trace(redefine, class, constantpool)
1221     ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1222 } // end map_index()
1223 
1224 
1225 // Map old_index to new_index as needed.
1226 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1227   if (find_new_operand_index(old_index) != -1) {
1228     // old_index is already mapped
1229     return;
1230   }
1231 
1232   if (old_index == new_index) {
1233     // no mapping is needed
1234     return;
1235   }
1236 
1237   _operands_index_map_p->at_put(old_index, new_index);
1238   _operands_index_map_count++;
1239 
1240   log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1241 } // end map_index()
1242 
1243 
1244 // Merge old_cp and scratch_cp and return the results of the merge via
1245 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1246 // merge_cp_length_p. The entries in old_cp occupy the same locations
1247 // in *merge_cp_p. Also creates a map of indices from entries in
1248 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1249 // entries are only created for entries in scratch_cp that occupy a
1250 // different location in *merged_cp_p.
1251 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1252        const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1253        int *merge_cp_length_p, TRAPS) {
1254 
1255   if (merge_cp_p == NULL) {
1256     assert(false, "caller must provide scratch constantPool");
1257     return false; // robustness
1258   }
1259   if (merge_cp_length_p == NULL) {
1260     assert(false, "caller must provide scratch CP length");
1261     return false; // robustness
1262   }
1263   // Worst case we need old_cp->length() + scratch_cp()->length(),
1264   // but the caller might be smart so make sure we have at least
1265   // the minimum.
1266   if ((*merge_cp_p)->length() < old_cp->length()) {
1267     assert(false, "merge area too small");
1268     return false; // robustness
1269   }
1270 
1271   log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1272 
1273   {
1274     // Pass 0:
1275     // The old_cp is copied to *merge_cp_p; this means that any code
1276     // using old_cp does not have to change. This work looks like a
1277     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1278     // handle one special case:
1279     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1280     // This will make verification happy.
1281 
1282     int old_i;  // index into old_cp
1283 
1284     // index zero (0) is not used in constantPools
1285     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1286       // leave debugging crumb
1287       jbyte old_tag = old_cp->tag_at(old_i).value();
1288       switch (old_tag) {
1289       case JVM_CONSTANT_Class:
1290       case JVM_CONSTANT_UnresolvedClass:
1291         // revert the copy to JVM_CONSTANT_UnresolvedClass
1292         // May be resolving while calling this so do the same for
1293         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1294         (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1295           old_cp->klass_name_index_at(old_i));
1296         break;
1297 
1298       case JVM_CONSTANT_Double:
1299       case JVM_CONSTANT_Long:
1300         // just copy the entry to *merge_cp_p, but double and long take
1301         // two constant pool entries
1302         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1303         old_i++;
1304         break;
1305 
1306       default:
1307         // just copy the entry to *merge_cp_p
1308         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1309         break;
1310       }
1311     } // end for each old_cp entry
1312 
1313     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1314     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1315 
1316     // We don't need to sanity check that *merge_cp_length_p is within
1317     // *merge_cp_p bounds since we have the minimum on-entry check above.
1318     (*merge_cp_length_p) = old_i;
1319   }
1320 
1321   // merge_cp_len should be the same as old_cp->length() at this point
1322   // so this trace message is really a "warm-and-breathing" message.
1323   log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1324 
1325   int scratch_i;  // index into scratch_cp
1326   {
1327     // Pass 1a:
1328     // Compare scratch_cp entries to the old_cp entries that we have
1329     // already copied to *merge_cp_p. In this pass, we are eliminating
1330     // exact duplicates (matching entry at same index) so we only
1331     // compare entries in the common indice range.
1332     int increment = 1;
1333     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1334     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1335       switch (scratch_cp->tag_at(scratch_i).value()) {
1336       case JVM_CONSTANT_Double:
1337       case JVM_CONSTANT_Long:
1338         // double and long take two constant pool entries
1339         increment = 2;
1340         break;
1341 
1342       default:
1343         increment = 1;
1344         break;
1345       }
1346 
1347       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1348         scratch_i, CHECK_0);
1349       if (match) {
1350         // found a match at the same index so nothing more to do
1351         continue;
1352       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1353                                               *merge_cp_p, scratch_i)) {
1354         // The mismatch in compare_entry_to() above is because of a
1355         // resolved versus unresolved class entry at the same index
1356         // with the same string value. Since Pass 0 reverted any
1357         // class entries to unresolved class entries in *merge_cp_p,
1358         // we go with the unresolved class entry.
1359         continue;
1360       }
1361 
1362       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1363         CHECK_0);
1364       if (found_i != 0) {
1365         guarantee(found_i != scratch_i,
1366           "compare_entry_to() and find_matching_entry() do not agree");
1367 
1368         // Found a matching entry somewhere else in *merge_cp_p so
1369         // just need a mapping entry.
1370         map_index(scratch_cp, scratch_i, found_i);
1371         continue;
1372       }
1373 
1374       // The find_matching_entry() call above could fail to find a match
1375       // due to a resolved versus unresolved class or string entry situation
1376       // like we solved above with the is_unresolved_*_mismatch() calls.
1377       // However, we would have to call is_unresolved_*_mismatch() over
1378       // all of *merge_cp_p (potentially) and that doesn't seem to be
1379       // worth the time.
1380 
1381       // No match found so we have to append this entry and any unique
1382       // referenced entries to *merge_cp_p.
1383       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1384         CHECK_0);
1385     }
1386   }
1387 
1388   log_debug(redefine, class, constantpool)
1389     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1390      *merge_cp_length_p, scratch_i, _index_map_count);
1391 
1392   if (scratch_i < scratch_cp->length()) {
1393     // Pass 1b:
1394     // old_cp is smaller than scratch_cp so there are entries in
1395     // scratch_cp that we have not yet processed. We take care of
1396     // those now.
1397     int increment = 1;
1398     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1399       switch (scratch_cp->tag_at(scratch_i).value()) {
1400       case JVM_CONSTANT_Double:
1401       case JVM_CONSTANT_Long:
1402         // double and long take two constant pool entries
1403         increment = 2;
1404         break;
1405 
1406       default:
1407         increment = 1;
1408         break;
1409       }
1410 
1411       int found_i =
1412         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1413       if (found_i != 0) {
1414         // Found a matching entry somewhere else in *merge_cp_p so
1415         // just need a mapping entry.
1416         map_index(scratch_cp, scratch_i, found_i);
1417         continue;
1418       }
1419 
1420       // No match found so we have to append this entry and any unique
1421       // referenced entries to *merge_cp_p.
1422       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1423         CHECK_0);
1424     }
1425 
1426     log_debug(redefine, class, constantpool)
1427       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1428        *merge_cp_length_p, scratch_i, _index_map_count);
1429   }
1430   finalize_operands_merge(*merge_cp_p, THREAD);
1431 
1432   return true;
1433 } // end merge_constant_pools()
1434 
1435 
1436 // Scoped object to clean up the constant pool(s) created for merging
1437 class MergeCPCleaner {
1438   ClassLoaderData*   _loader_data;
1439   ConstantPool*      _cp;
1440   ConstantPool*      _scratch_cp;
1441  public:
1442   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1443                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1444   ~MergeCPCleaner() {
1445     _loader_data->add_to_deallocate_list(_cp);
1446     if (_scratch_cp != NULL) {
1447       _loader_data->add_to_deallocate_list(_scratch_cp);
1448     }
1449   }
1450   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1451 };
1452 
1453 // Merge constant pools between the_class and scratch_class and
1454 // potentially rewrite bytecodes in scratch_class to use the merged
1455 // constant pool.
1456 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1457              InstanceKlass* the_class, InstanceKlass* scratch_class,
1458              TRAPS) {
1459   // worst case merged constant pool length is old and new combined
1460   int merge_cp_length = the_class->constants()->length()
1461         + scratch_class->constants()->length();
1462 
1463   // Constant pools are not easily reused so we allocate a new one
1464   // each time.
1465   // merge_cp is created unsafe for concurrent GC processing.  It
1466   // should be marked safe before discarding it. Even though
1467   // garbage,  if it crosses a card boundary, it may be scanned
1468   // in order to find the start of the first complete object on the card.
1469   ClassLoaderData* loader_data = the_class->class_loader_data();
1470   ConstantPool* merge_cp_oop =
1471     ConstantPool::allocate(loader_data,
1472                            merge_cp_length,
1473                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1474   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1475 
1476   HandleMark hm(THREAD);  // make sure handles are cleared before
1477                           // MergeCPCleaner clears out merge_cp_oop
1478   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1479 
1480   // Get constants() from the old class because it could have been rewritten
1481   // while we were at a safepoint allocating a new constant pool.
1482   constantPoolHandle old_cp(THREAD, the_class->constants());
1483   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1484 
1485   // If the length changed, the class was redefined out from under us. Return
1486   // an error.
1487   if (merge_cp_length != the_class->constants()->length()
1488          + scratch_class->constants()->length()) {
1489     return JVMTI_ERROR_INTERNAL;
1490   }
1491 
1492   // Update the version number of the constant pools (may keep scratch_cp)
1493   merge_cp->increment_and_save_version(old_cp->version());
1494   scratch_cp->increment_and_save_version(old_cp->version());
1495 
1496   ResourceMark rm(THREAD);
1497   _index_map_count = 0;
1498   _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1499 
1500   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1501   _operands_index_map_count = 0;
1502   int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1503   _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1504 
1505   // reference to the cp holder is needed for copy_operands()
1506   merge_cp->set_pool_holder(scratch_class);
1507   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1508                   &merge_cp_length, THREAD);
1509   merge_cp->set_pool_holder(NULL);
1510 
1511   if (!result) {
1512     // The merge can fail due to memory allocation failure or due
1513     // to robustness checks.
1514     return JVMTI_ERROR_INTERNAL;
1515   }
1516 
1517   log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1518 
1519   if (_index_map_count == 0) {
1520     // there is nothing to map between the new and merged constant pools
1521 
1522     if (old_cp->length() == scratch_cp->length()) {
1523       // The old and new constant pools are the same length and the
1524       // index map is empty. This means that the three constant pools
1525       // are equivalent (but not the same). Unfortunately, the new
1526       // constant pool has not gone through link resolution nor have
1527       // the new class bytecodes gone through constant pool cache
1528       // rewriting so we can't use the old constant pool with the new
1529       // class.
1530 
1531       // toss the merged constant pool at return
1532     } else if (old_cp->length() < scratch_cp->length()) {
1533       // The old constant pool has fewer entries than the new constant
1534       // pool and the index map is empty. This means the new constant
1535       // pool is a superset of the old constant pool. However, the old
1536       // class bytecodes have already gone through constant pool cache
1537       // rewriting so we can't use the new constant pool with the old
1538       // class.
1539 
1540       // toss the merged constant pool at return
1541     } else {
1542       // The old constant pool has more entries than the new constant
1543       // pool and the index map is empty. This means that both the old
1544       // and merged constant pools are supersets of the new constant
1545       // pool.
1546 
1547       // Replace the new constant pool with a shrunken copy of the
1548       // merged constant pool
1549       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1550                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1551       // The new constant pool replaces scratch_cp so have cleaner clean it up.
1552       // It can't be cleaned up while there are handles to it.
1553       cp_cleaner.add_scratch_cp(scratch_cp());
1554     }
1555   } else {
1556     if (log_is_enabled(Trace, redefine, class, constantpool)) {
1557       // don't want to loop unless we are tracing
1558       int count = 0;
1559       for (int i = 1; i < _index_map_p->length(); i++) {
1560         int value = _index_map_p->at(i);
1561 
1562         if (value != -1) {
1563           log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1564           count++;
1565         }
1566       }
1567     }
1568 
1569     // We have entries mapped between the new and merged constant pools
1570     // so we have to rewrite some constant pool references.
1571     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1572       return JVMTI_ERROR_INTERNAL;
1573     }
1574 
1575     // Replace the new constant pool with a shrunken copy of the
1576     // merged constant pool so now the rewritten bytecodes have
1577     // valid references; the previous new constant pool will get
1578     // GCed.
1579     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1580                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1581     // The new constant pool replaces scratch_cp so have cleaner clean it up.
1582     // It can't be cleaned up while there are handles to it.
1583     cp_cleaner.add_scratch_cp(scratch_cp());
1584   }
1585 
1586   return JVMTI_ERROR_NONE;
1587 } // end merge_cp_and_rewrite()
1588 
1589 
1590 // Rewrite constant pool references in klass scratch_class.
1591 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1592        TRAPS) {
1593 
1594   // rewrite constant pool references in the methods:
1595   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1596     // propagate failure back to caller
1597     return false;
1598   }
1599 
1600   // rewrite constant pool references in the class_annotations:
1601   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1602     // propagate failure back to caller
1603     return false;
1604   }
1605 
1606   // rewrite constant pool references in the fields_annotations:
1607   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1608     // propagate failure back to caller
1609     return false;
1610   }
1611 
1612   // rewrite constant pool references in the methods_annotations:
1613   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1614     // propagate failure back to caller
1615     return false;
1616   }
1617 
1618   // rewrite constant pool references in the methods_parameter_annotations:
1619   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1620          THREAD)) {
1621     // propagate failure back to caller
1622     return false;
1623   }
1624 
1625   // rewrite constant pool references in the methods_default_annotations:
1626   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1627          THREAD)) {
1628     // propagate failure back to caller
1629     return false;
1630   }
1631 
1632   // rewrite constant pool references in the class_type_annotations:
1633   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1634     // propagate failure back to caller
1635     return false;
1636   }
1637 
1638   // rewrite constant pool references in the fields_type_annotations:
1639   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1640     // propagate failure back to caller
1641     return false;
1642   }
1643 
1644   // rewrite constant pool references in the methods_type_annotations:
1645   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1646     // propagate failure back to caller
1647     return false;
1648   }
1649 
1650   // There can be type annotations in the Code part of a method_info attribute.
1651   // These annotations are not accessible, even by reflection.
1652   // Currently they are not even parsed by the ClassFileParser.
1653   // If runtime access is added they will also need to be rewritten.
1654 
1655   // rewrite source file name index:
1656   u2 source_file_name_idx = scratch_class->source_file_name_index();
1657   if (source_file_name_idx != 0) {
1658     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1659     if (new_source_file_name_idx != 0) {
1660       scratch_class->set_source_file_name_index(new_source_file_name_idx);
1661     }
1662   }
1663 
1664   // rewrite class generic signature index:
1665   u2 generic_signature_index = scratch_class->generic_signature_index();
1666   if (generic_signature_index != 0) {
1667     u2 new_generic_signature_index = find_new_index(generic_signature_index);
1668     if (new_generic_signature_index != 0) {
1669       scratch_class->set_generic_signature_index(new_generic_signature_index);
1670     }
1671   }
1672 
1673   return true;
1674 } // end rewrite_cp_refs()
1675 
1676 // Rewrite constant pool references in the methods.
1677 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1678        InstanceKlass* scratch_class, TRAPS) {
1679 
1680   Array<Method*>* methods = scratch_class->methods();
1681 
1682   if (methods == NULL || methods->length() == 0) {
1683     // no methods so nothing to do
1684     return true;
1685   }
1686 
1687   // rewrite constant pool references in the methods:
1688   for (int i = methods->length() - 1; i >= 0; i--) {
1689     methodHandle method(THREAD, methods->at(i));
1690     methodHandle new_method;
1691     rewrite_cp_refs_in_method(method, &new_method, THREAD);
1692     if (!new_method.is_null()) {
1693       // the method has been replaced so save the new method version
1694       // even in the case of an exception.  original method is on the
1695       // deallocation list.
1696       methods->at_put(i, new_method());
1697     }
1698     if (HAS_PENDING_EXCEPTION) {
1699       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1700       log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1701       // Need to clear pending exception here as the super caller sets
1702       // the JVMTI_ERROR_INTERNAL if the returned value is false.
1703       CLEAR_PENDING_EXCEPTION;
1704       return false;
1705     }
1706   }
1707 
1708   return true;
1709 }
1710 
1711 
1712 // Rewrite constant pool references in the specific method. This code
1713 // was adapted from Rewriter::rewrite_method().
1714 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1715        methodHandle *new_method_p, TRAPS) {
1716 
1717   *new_method_p = methodHandle();  // default is no new method
1718 
1719   // We cache a pointer to the bytecodes here in code_base. If GC
1720   // moves the Method*, then the bytecodes will also move which
1721   // will likely cause a crash. We create a NoSafepointVerifier
1722   // object to detect whether we pass a possible safepoint in this
1723   // code block.
1724   NoSafepointVerifier nsv;
1725 
1726   // Bytecodes and their length
1727   address code_base = method->code_base();
1728   int code_length = method->code_size();
1729 
1730   int bc_length;
1731   for (int bci = 0; bci < code_length; bci += bc_length) {
1732     address bcp = code_base + bci;
1733     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1734 
1735     bc_length = Bytecodes::length_for(c);
1736     if (bc_length == 0) {
1737       // More complicated bytecodes report a length of zero so
1738       // we have to try again a slightly different way.
1739       bc_length = Bytecodes::length_at(method(), bcp);
1740     }
1741 
1742     assert(bc_length != 0, "impossible bytecode length");
1743 
1744     switch (c) {
1745       case Bytecodes::_ldc:
1746       {
1747         int cp_index = *(bcp + 1);
1748         int new_index = find_new_index(cp_index);
1749 
1750         if (StressLdcRewrite && new_index == 0) {
1751           // If we are stressing ldc -> ldc_w rewriting, then we
1752           // always need a new_index value.
1753           new_index = cp_index;
1754         }
1755         if (new_index != 0) {
1756           // the original index is mapped so we have more work to do
1757           if (!StressLdcRewrite && new_index <= max_jubyte) {
1758             // The new value can still use ldc instead of ldc_w
1759             // unless we are trying to stress ldc -> ldc_w rewriting
1760             log_trace(redefine, class, constantpool)
1761               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1762             *(bcp + 1) = new_index;
1763           } else {
1764             log_trace(redefine, class, constantpool)
1765               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1766             // the new value needs ldc_w instead of ldc
1767             u_char inst_buffer[4]; // max instruction size is 4 bytes
1768             bcp = (address)inst_buffer;
1769             // construct new instruction sequence
1770             *bcp = Bytecodes::_ldc_w;
1771             bcp++;
1772             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1773             // See comment below for difference between put_Java_u2()
1774             // and put_native_u2().
1775             Bytes::put_Java_u2(bcp, new_index);
1776 
1777             Relocator rc(method, NULL /* no RelocatorListener needed */);
1778             methodHandle m;
1779             {
1780               PauseNoSafepointVerifier pnsv(&nsv);
1781 
1782               // ldc is 2 bytes and ldc_w is 3 bytes
1783               m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1784             }
1785 
1786             // return the new method so that the caller can update
1787             // the containing class
1788             *new_method_p = method = m;
1789             // switch our bytecode processing loop from the old method
1790             // to the new method
1791             code_base = method->code_base();
1792             code_length = method->code_size();
1793             bcp = code_base + bci;
1794             c = (Bytecodes::Code)(*bcp);
1795             bc_length = Bytecodes::length_for(c);
1796             assert(bc_length != 0, "sanity check");
1797           } // end we need ldc_w instead of ldc
1798         } // end if there is a mapped index
1799       } break;
1800 
1801       // these bytecodes have a two-byte constant pool index
1802       case Bytecodes::_anewarray      : // fall through
1803       case Bytecodes::_checkcast      : // fall through
1804       case Bytecodes::_getfield       : // fall through
1805       case Bytecodes::_getstatic      : // fall through
1806       case Bytecodes::_instanceof     : // fall through
1807       case Bytecodes::_invokedynamic  : // fall through
1808       case Bytecodes::_invokeinterface: // fall through
1809       case Bytecodes::_invokespecial  : // fall through
1810       case Bytecodes::_invokestatic   : // fall through
1811       case Bytecodes::_invokevirtual  : // fall through
1812       case Bytecodes::_ldc_w          : // fall through
1813       case Bytecodes::_ldc2_w         : // fall through
1814       case Bytecodes::_multianewarray : // fall through
1815       case Bytecodes::_new            : // fall through
1816       case Bytecodes::_putfield       : // fall through
1817       case Bytecodes::_putstatic      :
1818       {
1819         address p = bcp + 1;
1820         int cp_index = Bytes::get_Java_u2(p);
1821         int new_index = find_new_index(cp_index);
1822         if (new_index != 0) {
1823           // the original index is mapped so update w/ new value
1824           log_trace(redefine, class, constantpool)
1825             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
1826           // Rewriter::rewrite_method() uses put_native_u2() in this
1827           // situation because it is reusing the constant pool index
1828           // location for a native index into the ConstantPoolCache.
1829           // Since we are updating the constant pool index prior to
1830           // verification and ConstantPoolCache initialization, we
1831           // need to keep the new index in Java byte order.
1832           Bytes::put_Java_u2(p, new_index);
1833         }
1834       } break;
1835       default:
1836         break;
1837     }
1838   } // end for each bytecode
1839 
1840   // We also need to rewrite the parameter name indexes, if there is
1841   // method parameter data present
1842   if(method->has_method_parameters()) {
1843     const int len = method->method_parameters_length();
1844     MethodParametersElement* elem = method->method_parameters_start();
1845 
1846     for (int i = 0; i < len; i++) {
1847       const u2 cp_index = elem[i].name_cp_index;
1848       const u2 new_cp_index = find_new_index(cp_index);
1849       if (new_cp_index != 0) {
1850         elem[i].name_cp_index = new_cp_index;
1851       }
1852     }
1853   }
1854 } // end rewrite_cp_refs_in_method()
1855 
1856 
1857 // Rewrite constant pool references in the class_annotations field.
1858 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1859        InstanceKlass* scratch_class, TRAPS) {
1860 
1861   AnnotationArray* class_annotations = scratch_class->class_annotations();
1862   if (class_annotations == NULL || class_annotations->length() == 0) {
1863     // no class_annotations so nothing to do
1864     return true;
1865   }
1866 
1867   log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
1868 
1869   int byte_i = 0;  // byte index into class_annotations
1870   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1871            THREAD);
1872 }
1873 
1874 
1875 // Rewrite constant pool references in an annotations typeArray. This
1876 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1877 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1878 //
1879 // annotations_typeArray {
1880 //   u2 num_annotations;
1881 //   annotation annotations[num_annotations];
1882 // }
1883 //
1884 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1885        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1886 
1887   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1888     // not enough room for num_annotations field
1889     log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
1890     return false;
1891   }
1892 
1893   u2 num_annotations = Bytes::get_Java_u2((address)
1894                          annotations_typeArray->adr_at(byte_i_ref));
1895   byte_i_ref += 2;
1896 
1897   log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
1898 
1899   int calc_num_annotations = 0;
1900   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1901     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1902            byte_i_ref, THREAD)) {
1903       log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
1904       // propagate failure back to caller
1905       return false;
1906     }
1907   }
1908   assert(num_annotations == calc_num_annotations, "sanity check");
1909 
1910   return true;
1911 } // end rewrite_cp_refs_in_annotations_typeArray()
1912 
1913 
1914 // Rewrite constant pool references in the annotation struct portion of
1915 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1916 // the 2nd-edition of the VM spec:
1917 //
1918 // struct annotation {
1919 //   u2 type_index;
1920 //   u2 num_element_value_pairs;
1921 //   {
1922 //     u2 element_name_index;
1923 //     element_value value;
1924 //   } element_value_pairs[num_element_value_pairs];
1925 // }
1926 //
1927 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1928        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1929   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1930     // not enough room for smallest annotation_struct
1931     log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
1932     return false;
1933   }
1934 
1935   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1936                     byte_i_ref, "type_index", THREAD);
1937 
1938   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1939                                  annotations_typeArray->adr_at(byte_i_ref));
1940   byte_i_ref += 2;
1941 
1942   log_debug(redefine, class, annotation)
1943     ("type_index=%d  num_element_value_pairs=%d", type_index, num_element_value_pairs);
1944 
1945   int calc_num_element_value_pairs = 0;
1946   for (; calc_num_element_value_pairs < num_element_value_pairs;
1947        calc_num_element_value_pairs++) {
1948     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1949       // not enough room for another element_name_index, let alone
1950       // the rest of another component
1951       log_debug(redefine, class, annotation)("length() is too small for element_name_index");
1952       return false;
1953     }
1954 
1955     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1956                               annotations_typeArray, byte_i_ref,
1957                               "element_name_index", THREAD);
1958 
1959     log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
1960 
1961     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1962            byte_i_ref, THREAD)) {
1963       log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
1964       // propagate failure back to caller
1965       return false;
1966     }
1967   } // end for each component
1968   assert(num_element_value_pairs == calc_num_element_value_pairs,
1969     "sanity check");
1970 
1971   return true;
1972 } // end rewrite_cp_refs_in_annotation_struct()
1973 
1974 
1975 // Rewrite a constant pool reference at the current position in
1976 // annotations_typeArray if needed. Returns the original constant
1977 // pool reference if a rewrite was not needed or the new constant
1978 // pool reference if a rewrite was needed.
1979 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1980      AnnotationArray* annotations_typeArray, int &byte_i_ref,
1981      const char * trace_mesg, TRAPS) {
1982 
1983   address cp_index_addr = (address)
1984     annotations_typeArray->adr_at(byte_i_ref);
1985   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1986   u2 new_cp_index = find_new_index(old_cp_index);
1987   if (new_cp_index != 0) {
1988     log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
1989     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1990     old_cp_index = new_cp_index;
1991   }
1992   byte_i_ref += 2;
1993   return old_cp_index;
1994 }
1995 
1996 
1997 // Rewrite constant pool references in the element_value portion of an
1998 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1999 // the 2nd-edition of the VM spec:
2000 //
2001 // struct element_value {
2002 //   u1 tag;
2003 //   union {
2004 //     u2 const_value_index;
2005 //     {
2006 //       u2 type_name_index;
2007 //       u2 const_name_index;
2008 //     } enum_const_value;
2009 //     u2 class_info_index;
2010 //     annotation annotation_value;
2011 //     struct {
2012 //       u2 num_values;
2013 //       element_value values[num_values];
2014 //     } array_value;
2015 //   } value;
2016 // }
2017 //
2018 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2019        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2020 
2021   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2022     // not enough room for a tag let alone the rest of an element_value
2023     log_debug(redefine, class, annotation)("length() is too small for a tag");
2024     return false;
2025   }
2026 
2027   u1 tag = annotations_typeArray->at(byte_i_ref);
2028   byte_i_ref++;
2029   log_debug(redefine, class, annotation)("tag='%c'", tag);
2030 
2031   switch (tag) {
2032     // These BaseType tag values are from Table 4.2 in VM spec:
2033     case 'B':  // byte
2034     case 'C':  // char
2035     case 'D':  // double
2036     case 'F':  // float
2037     case 'I':  // int
2038     case 'J':  // long
2039     case 'S':  // short
2040     case 'Z':  // boolean
2041 
2042     // The remaining tag values are from Table 4.8 in the 2nd-edition of
2043     // the VM spec:
2044     case 's':
2045     {
2046       // For the above tag values (including the BaseType values),
2047       // value.const_value_index is right union field.
2048 
2049       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2050         // not enough room for a const_value_index
2051         log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2052         return false;
2053       }
2054 
2055       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2056                                annotations_typeArray, byte_i_ref,
2057                                "const_value_index", THREAD);
2058 
2059       log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2060     } break;
2061 
2062     case 'e':
2063     {
2064       // for the above tag value, value.enum_const_value is right union field
2065 
2066       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2067         // not enough room for a enum_const_value
2068         log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2069         return false;
2070       }
2071 
2072       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2073                              annotations_typeArray, byte_i_ref,
2074                              "type_name_index", THREAD);
2075 
2076       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2077                               annotations_typeArray, byte_i_ref,
2078                               "const_name_index", THREAD);
2079 
2080       log_debug(redefine, class, annotation)
2081         ("type_name_index=%d  const_name_index=%d", type_name_index, const_name_index);
2082     } break;
2083 
2084     case 'c':
2085     {
2086       // for the above tag value, value.class_info_index is right union field
2087 
2088       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2089         // not enough room for a class_info_index
2090         log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2091         return false;
2092       }
2093 
2094       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2095                               annotations_typeArray, byte_i_ref,
2096                               "class_info_index", THREAD);
2097 
2098       log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2099     } break;
2100 
2101     case '@':
2102       // For the above tag value, value.attr_value is the right union
2103       // field. This is a nested annotation.
2104       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2105              byte_i_ref, THREAD)) {
2106         // propagate failure back to caller
2107         return false;
2108       }
2109       break;
2110 
2111     case '[':
2112     {
2113       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2114         // not enough room for a num_values field
2115         log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2116         return false;
2117       }
2118 
2119       // For the above tag value, value.array_value is the right union
2120       // field. This is an array of nested element_value.
2121       u2 num_values = Bytes::get_Java_u2((address)
2122                         annotations_typeArray->adr_at(byte_i_ref));
2123       byte_i_ref += 2;
2124       log_debug(redefine, class, annotation)("num_values=%d", num_values);
2125 
2126       int calc_num_values = 0;
2127       for (; calc_num_values < num_values; calc_num_values++) {
2128         if (!rewrite_cp_refs_in_element_value(
2129                annotations_typeArray, byte_i_ref, THREAD)) {
2130           log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2131           // propagate failure back to caller
2132           return false;
2133         }
2134       }
2135       assert(num_values == calc_num_values, "sanity check");
2136     } break;
2137 
2138     default:
2139       log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2140       return false;
2141   } // end decode tag field
2142 
2143   return true;
2144 } // end rewrite_cp_refs_in_element_value()
2145 
2146 
2147 // Rewrite constant pool references in a fields_annotations field.
2148 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2149        InstanceKlass* scratch_class, TRAPS) {
2150 
2151   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2152 
2153   if (fields_annotations == NULL || fields_annotations->length() == 0) {
2154     // no fields_annotations so nothing to do
2155     return true;
2156   }
2157 
2158   log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2159 
2160   for (int i = 0; i < fields_annotations->length(); i++) {
2161     AnnotationArray* field_annotations = fields_annotations->at(i);
2162     if (field_annotations == NULL || field_annotations->length() == 0) {
2163       // this field does not have any annotations so skip it
2164       continue;
2165     }
2166 
2167     int byte_i = 0;  // byte index into field_annotations
2168     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2169            THREAD)) {
2170       log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2171       // propagate failure back to caller
2172       return false;
2173     }
2174   }
2175 
2176   return true;
2177 } // end rewrite_cp_refs_in_fields_annotations()
2178 
2179 
2180 // Rewrite constant pool references in a methods_annotations field.
2181 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2182        InstanceKlass* scratch_class, TRAPS) {
2183 
2184   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2185     Method* m = scratch_class->methods()->at(i);
2186     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2187 
2188     if (method_annotations == NULL || method_annotations->length() == 0) {
2189       // this method does not have any annotations so skip it
2190       continue;
2191     }
2192 
2193     int byte_i = 0;  // byte index into method_annotations
2194     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2195            THREAD)) {
2196       log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2197       // propagate failure back to caller
2198       return false;
2199     }
2200   }
2201 
2202   return true;
2203 } // end rewrite_cp_refs_in_methods_annotations()
2204 
2205 
2206 // Rewrite constant pool references in a methods_parameter_annotations
2207 // field. This "structure" is adapted from the
2208 // RuntimeVisibleParameterAnnotations_attribute described in section
2209 // 4.8.17 of the 2nd-edition of the VM spec:
2210 //
2211 // methods_parameter_annotations_typeArray {
2212 //   u1 num_parameters;
2213 //   {
2214 //     u2 num_annotations;
2215 //     annotation annotations[num_annotations];
2216 //   } parameter_annotations[num_parameters];
2217 // }
2218 //
2219 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2220        InstanceKlass* scratch_class, TRAPS) {
2221 
2222   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2223     Method* m = scratch_class->methods()->at(i);
2224     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2225     if (method_parameter_annotations == NULL
2226         || method_parameter_annotations->length() == 0) {
2227       // this method does not have any parameter annotations so skip it
2228       continue;
2229     }
2230 
2231     if (method_parameter_annotations->length() < 1) {
2232       // not enough room for a num_parameters field
2233       log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2234       return false;
2235     }
2236 
2237     int byte_i = 0;  // byte index into method_parameter_annotations
2238 
2239     u1 num_parameters = method_parameter_annotations->at(byte_i);
2240     byte_i++;
2241 
2242     log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2243 
2244     int calc_num_parameters = 0;
2245     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2246       if (!rewrite_cp_refs_in_annotations_typeArray(
2247              method_parameter_annotations, byte_i, THREAD)) {
2248         log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2249         // propagate failure back to caller
2250         return false;
2251       }
2252     }
2253     assert(num_parameters == calc_num_parameters, "sanity check");
2254   }
2255 
2256   return true;
2257 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2258 
2259 
2260 // Rewrite constant pool references in a methods_default_annotations
2261 // field. This "structure" is adapted from the AnnotationDefault_attribute
2262 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2263 //
2264 // methods_default_annotations_typeArray {
2265 //   element_value default_value;
2266 // }
2267 //
2268 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2269        InstanceKlass* scratch_class, TRAPS) {
2270 
2271   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2272     Method* m = scratch_class->methods()->at(i);
2273     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2274     if (method_default_annotations == NULL
2275         || method_default_annotations->length() == 0) {
2276       // this method does not have any default annotations so skip it
2277       continue;
2278     }
2279 
2280     int byte_i = 0;  // byte index into method_default_annotations
2281 
2282     if (!rewrite_cp_refs_in_element_value(
2283            method_default_annotations, byte_i, THREAD)) {
2284       log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2285       // propagate failure back to caller
2286       return false;
2287     }
2288   }
2289 
2290   return true;
2291 } // end rewrite_cp_refs_in_methods_default_annotations()
2292 
2293 
2294 // Rewrite constant pool references in a class_type_annotations field.
2295 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2296        InstanceKlass* scratch_class, TRAPS) {
2297 
2298   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2299   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2300     // no class_type_annotations so nothing to do
2301     return true;
2302   }
2303 
2304   log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2305 
2306   int byte_i = 0;  // byte index into class_type_annotations
2307   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2308       byte_i, "ClassFile", THREAD);
2309 } // end rewrite_cp_refs_in_class_type_annotations()
2310 
2311 
2312 // Rewrite constant pool references in a fields_type_annotations field.
2313 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2314        InstanceKlass* scratch_class, TRAPS) {
2315 
2316   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2317   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2318     // no fields_type_annotations so nothing to do
2319     return true;
2320   }
2321 
2322   log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2323 
2324   for (int i = 0; i < fields_type_annotations->length(); i++) {
2325     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2326     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2327       // this field does not have any annotations so skip it
2328       continue;
2329     }
2330 
2331     int byte_i = 0;  // byte index into field_type_annotations
2332     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2333            byte_i, "field_info", THREAD)) {
2334       log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2335       // propagate failure back to caller
2336       return false;
2337     }
2338   }
2339 
2340   return true;
2341 } // end rewrite_cp_refs_in_fields_type_annotations()
2342 
2343 
2344 // Rewrite constant pool references in a methods_type_annotations field.
2345 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2346        InstanceKlass* scratch_class, TRAPS) {
2347 
2348   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2349     Method* m = scratch_class->methods()->at(i);
2350     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2351 
2352     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2353       // this method does not have any annotations so skip it
2354       continue;
2355     }
2356 
2357     log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2358 
2359     int byte_i = 0;  // byte index into method_type_annotations
2360     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2361            byte_i, "method_info", THREAD)) {
2362       log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2363       // propagate failure back to caller
2364       return false;
2365     }
2366   }
2367 
2368   return true;
2369 } // end rewrite_cp_refs_in_methods_type_annotations()
2370 
2371 
2372 // Rewrite constant pool references in a type_annotations
2373 // field. This "structure" is adapted from the
2374 // RuntimeVisibleTypeAnnotations_attribute described in
2375 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2376 //
2377 // type_annotations_typeArray {
2378 //   u2              num_annotations;
2379 //   type_annotation annotations[num_annotations];
2380 // }
2381 //
2382 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2383        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2384        const char * location_mesg, TRAPS) {
2385 
2386   if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2387     // not enough room for num_annotations field
2388     log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2389     return false;
2390   }
2391 
2392   u2 num_annotations = Bytes::get_Java_u2((address)
2393                          type_annotations_typeArray->adr_at(byte_i_ref));
2394   byte_i_ref += 2;
2395 
2396   log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2397 
2398   int calc_num_annotations = 0;
2399   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2400     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2401            byte_i_ref, location_mesg, THREAD)) {
2402       log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2403       // propagate failure back to caller
2404       return false;
2405     }
2406   }
2407   assert(num_annotations == calc_num_annotations, "sanity check");
2408 
2409   if (byte_i_ref != type_annotations_typeArray->length()) {
2410     log_debug(redefine, class, annotation)
2411       ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2412        byte_i_ref, type_annotations_typeArray->length());
2413     return false;
2414   }
2415 
2416   return true;
2417 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2418 
2419 
2420 // Rewrite constant pool references in a type_annotation
2421 // field. This "structure" is adapted from the
2422 // RuntimeVisibleTypeAnnotations_attribute described in
2423 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2424 //
2425 // type_annotation {
2426 //   u1 target_type;
2427 //   union {
2428 //     type_parameter_target;
2429 //     supertype_target;
2430 //     type_parameter_bound_target;
2431 //     empty_target;
2432 //     method_formal_parameter_target;
2433 //     throws_target;
2434 //     localvar_target;
2435 //     catch_target;
2436 //     offset_target;
2437 //     type_argument_target;
2438 //   } target_info;
2439 //   type_path target_path;
2440 //   annotation anno;
2441 // }
2442 //
2443 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2444        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2445        const char * location_mesg, TRAPS) {
2446 
2447   if (!skip_type_annotation_target(type_annotations_typeArray,
2448          byte_i_ref, location_mesg, THREAD)) {
2449     return false;
2450   }
2451 
2452   if (!skip_type_annotation_type_path(type_annotations_typeArray,
2453          byte_i_ref, THREAD)) {
2454     return false;
2455   }
2456 
2457   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2458          byte_i_ref, THREAD)) {
2459     return false;
2460   }
2461 
2462   return true;
2463 } // end rewrite_cp_refs_in_type_annotation_struct()
2464 
2465 
2466 // Read, verify and skip over the target_type and target_info part
2467 // so that rewriting can continue in the later parts of the struct.
2468 //
2469 // u1 target_type;
2470 // union {
2471 //   type_parameter_target;
2472 //   supertype_target;
2473 //   type_parameter_bound_target;
2474 //   empty_target;
2475 //   method_formal_parameter_target;
2476 //   throws_target;
2477 //   localvar_target;
2478 //   catch_target;
2479 //   offset_target;
2480 //   type_argument_target;
2481 // } target_info;
2482 //
2483 bool VM_RedefineClasses::skip_type_annotation_target(
2484        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2485        const char * location_mesg, TRAPS) {
2486 
2487   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2488     // not enough room for a target_type let alone the rest of a type_annotation
2489     log_debug(redefine, class, annotation)("length() is too small for a target_type");
2490     return false;
2491   }
2492 
2493   u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2494   byte_i_ref += 1;
2495   log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2496   log_debug(redefine, class, annotation)("location=%s", location_mesg);
2497 
2498   // Skip over target_info
2499   switch (target_type) {
2500     case 0x00:
2501     // kind: type parameter declaration of generic class or interface
2502     // location: ClassFile
2503     case 0x01:
2504     // kind: type parameter declaration of generic method or constructor
2505     // location: method_info
2506 
2507     {
2508       // struct:
2509       // type_parameter_target {
2510       //   u1 type_parameter_index;
2511       // }
2512       //
2513       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2514         log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2515         return false;
2516       }
2517 
2518       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2519       byte_i_ref += 1;
2520 
2521       log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2522     } break;
2523 
2524     case 0x10:
2525     // kind: type in extends clause of class or interface declaration
2526     //       (including the direct superclass of an anonymous class declaration),
2527     //       or in implements clause of interface declaration
2528     // location: ClassFile
2529 
2530     {
2531       // struct:
2532       // supertype_target {
2533       //   u2 supertype_index;
2534       // }
2535       //
2536       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2537         log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2538         return false;
2539       }
2540 
2541       u2 supertype_index = Bytes::get_Java_u2((address)
2542                              type_annotations_typeArray->adr_at(byte_i_ref));
2543       byte_i_ref += 2;
2544 
2545       log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2546     } break;
2547 
2548     case 0x11:
2549     // kind: type in bound of type parameter declaration of generic class or interface
2550     // location: ClassFile
2551     case 0x12:
2552     // kind: type in bound of type parameter declaration of generic method or constructor
2553     // location: method_info
2554 
2555     {
2556       // struct:
2557       // type_parameter_bound_target {
2558       //   u1 type_parameter_index;
2559       //   u1 bound_index;
2560       // }
2561       //
2562       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2563         log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2564         return false;
2565       }
2566 
2567       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2568       byte_i_ref += 1;
2569       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2570       byte_i_ref += 1;
2571 
2572       log_debug(redefine, class, annotation)
2573         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2574     } break;
2575 
2576     case 0x13:
2577     // kind: type in field declaration
2578     // location: field_info
2579     case 0x14:
2580     // kind: return type of method, or type of newly constructed object
2581     // location: method_info
2582     case 0x15:
2583     // kind: receiver type of method or constructor
2584     // location: method_info
2585 
2586     {
2587       // struct:
2588       // empty_target {
2589       // }
2590       //
2591       log_debug(redefine, class, annotation)("empty_target");
2592     } break;
2593 
2594     case 0x16:
2595     // kind: type in formal parameter declaration of method, constructor, or lambda expression
2596     // location: method_info
2597 
2598     {
2599       // struct:
2600       // formal_parameter_target {
2601       //   u1 formal_parameter_index;
2602       // }
2603       //
2604       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2605         log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2606         return false;
2607       }
2608 
2609       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2610       byte_i_ref += 1;
2611 
2612       log_debug(redefine, class, annotation)
2613         ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2614     } break;
2615 
2616     case 0x17:
2617     // kind: type in throws clause of method or constructor
2618     // location: method_info
2619 
2620     {
2621       // struct:
2622       // throws_target {
2623       //   u2 throws_type_index
2624       // }
2625       //
2626       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2627         log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2628         return false;
2629       }
2630 
2631       u2 throws_type_index = Bytes::get_Java_u2((address)
2632                                type_annotations_typeArray->adr_at(byte_i_ref));
2633       byte_i_ref += 2;
2634 
2635       log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2636     } break;
2637 
2638     case 0x40:
2639     // kind: type in local variable declaration
2640     // location: Code
2641     case 0x41:
2642     // kind: type in resource variable declaration
2643     // location: Code
2644 
2645     {
2646       // struct:
2647       // localvar_target {
2648       //   u2 table_length;
2649       //   struct {
2650       //     u2 start_pc;
2651       //     u2 length;
2652       //     u2 index;
2653       //   } table[table_length];
2654       // }
2655       //
2656       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2657         // not enough room for a table_length let alone the rest of a localvar_target
2658         log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
2659         return false;
2660       }
2661 
2662       u2 table_length = Bytes::get_Java_u2((address)
2663                           type_annotations_typeArray->adr_at(byte_i_ref));
2664       byte_i_ref += 2;
2665 
2666       log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2667 
2668       int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2669       int table_size = table_length * table_struct_size;
2670 
2671       if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2672         // not enough room for a table
2673         log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2674         return false;
2675       }
2676 
2677       // Skip over table
2678       byte_i_ref += table_size;
2679     } break;
2680 
2681     case 0x42:
2682     // kind: type in exception parameter declaration
2683     // location: Code
2684 
2685     {
2686       // struct:
2687       // catch_target {
2688       //   u2 exception_table_index;
2689       // }
2690       //
2691       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2692         log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2693         return false;
2694       }
2695 
2696       u2 exception_table_index = Bytes::get_Java_u2((address)
2697                                    type_annotations_typeArray->adr_at(byte_i_ref));
2698       byte_i_ref += 2;
2699 
2700       log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2701     } break;
2702 
2703     case 0x43:
2704     // kind: type in instanceof expression
2705     // location: Code
2706     case 0x44:
2707     // kind: type in new expression
2708     // location: Code
2709     case 0x45:
2710     // kind: type in method reference expression using ::new
2711     // location: Code
2712     case 0x46:
2713     // kind: type in method reference expression using ::Identifier
2714     // location: Code
2715 
2716     {
2717       // struct:
2718       // offset_target {
2719       //   u2 offset;
2720       // }
2721       //
2722       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2723         log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2724         return false;
2725       }
2726 
2727       u2 offset = Bytes::get_Java_u2((address)
2728                     type_annotations_typeArray->adr_at(byte_i_ref));
2729       byte_i_ref += 2;
2730 
2731       log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2732     } break;
2733 
2734     case 0x47:
2735     // kind: type in cast expression
2736     // location: Code
2737     case 0x48:
2738     // kind: type argument for generic constructor in new expression or
2739     //       explicit constructor invocation statement
2740     // location: Code
2741     case 0x49:
2742     // kind: type argument for generic method in method invocation expression
2743     // location: Code
2744     case 0x4A:
2745     // kind: type argument for generic constructor in method reference expression using ::new
2746     // location: Code
2747     case 0x4B:
2748     // kind: type argument for generic method in method reference expression using ::Identifier
2749     // location: Code
2750 
2751     {
2752       // struct:
2753       // type_argument_target {
2754       //   u2 offset;
2755       //   u1 type_argument_index;
2756       // }
2757       //
2758       if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2759         log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
2760         return false;
2761       }
2762 
2763       u2 offset = Bytes::get_Java_u2((address)
2764                     type_annotations_typeArray->adr_at(byte_i_ref));
2765       byte_i_ref += 2;
2766       u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2767       byte_i_ref += 1;
2768 
2769       log_debug(redefine, class, annotation)
2770         ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
2771     } break;
2772 
2773     default:
2774       log_debug(redefine, class, annotation)("unknown target_type");
2775 #ifdef ASSERT
2776       ShouldNotReachHere();
2777 #endif
2778       return false;
2779   }
2780 
2781   return true;
2782 } // end skip_type_annotation_target()
2783 
2784 
2785 // Read, verify and skip over the type_path part so that rewriting
2786 // can continue in the later parts of the struct.
2787 //
2788 // type_path {
2789 //   u1 path_length;
2790 //   {
2791 //     u1 type_path_kind;
2792 //     u1 type_argument_index;
2793 //   } path[path_length];
2794 // }
2795 //
2796 bool VM_RedefineClasses::skip_type_annotation_type_path(
2797        AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2798 
2799   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2800     // not enough room for a path_length let alone the rest of the type_path
2801     log_debug(redefine, class, annotation)("length() is too small for a type_path");
2802     return false;
2803   }
2804 
2805   u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2806   byte_i_ref += 1;
2807 
2808   log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
2809 
2810   int calc_path_length = 0;
2811   for (; calc_path_length < path_length; calc_path_length++) {
2812     if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2813       // not enough room for a path
2814       log_debug(redefine, class, annotation)
2815         ("length() is too small for path entry %d of %d", calc_path_length, path_length);
2816       return false;
2817     }
2818 
2819     u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2820     byte_i_ref += 1;
2821     u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2822     byte_i_ref += 1;
2823 
2824     log_debug(redefine, class, annotation)
2825       ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2826        calc_path_length, type_path_kind, type_argument_index);
2827 
2828     if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2829       // not enough room for a path
2830       log_debug(redefine, class, annotation)("inconsistent type_path values");
2831       return false;
2832     }
2833   }
2834   assert(path_length == calc_path_length, "sanity check");
2835 
2836   return true;
2837 } // end skip_type_annotation_type_path()
2838 
2839 
2840 // Rewrite constant pool references in the method's stackmap table.
2841 // These "structures" are adapted from the StackMapTable_attribute that
2842 // is described in section 4.8.4 of the 6.0 version of the VM spec
2843 // (dated 2005.10.26):
2844 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2845 //
2846 // stack_map {
2847 //   u2 number_of_entries;
2848 //   stack_map_frame entries[number_of_entries];
2849 // }
2850 //
2851 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2852        const methodHandle& method, TRAPS) {
2853 
2854   if (!method->has_stackmap_table()) {
2855     return;
2856   }
2857 
2858   AnnotationArray* stackmap_data = method->stackmap_data();
2859   address stackmap_p = (address)stackmap_data->adr_at(0);
2860   address stackmap_end = stackmap_p + stackmap_data->length();
2861 
2862   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2863   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2864   stackmap_p += 2;
2865 
2866   log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
2867 
2868   // walk through each stack_map_frame
2869   u2 calc_number_of_entries = 0;
2870   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2871     // The stack_map_frame structure is a u1 frame_type followed by
2872     // 0 or more bytes of data:
2873     //
2874     // union stack_map_frame {
2875     //   same_frame;
2876     //   same_locals_1_stack_item_frame;
2877     //   same_locals_1_stack_item_frame_extended;
2878     //   chop_frame;
2879     //   same_frame_extended;
2880     //   append_frame;
2881     //   full_frame;
2882     // }
2883 
2884     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2885     u1 frame_type = *stackmap_p;
2886     stackmap_p++;
2887 
2888     // same_frame {
2889     //   u1 frame_type = SAME; /* 0-63 */
2890     // }
2891     if (frame_type <= 63) {
2892       // nothing more to do for same_frame
2893     }
2894 
2895     // same_locals_1_stack_item_frame {
2896     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2897     //   verification_type_info stack[1];
2898     // }
2899     else if (frame_type >= 64 && frame_type <= 127) {
2900       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2901         calc_number_of_entries, frame_type, THREAD);
2902     }
2903 
2904     // reserved for future use
2905     else if (frame_type >= 128 && frame_type <= 246) {
2906       // nothing more to do for reserved frame_types
2907     }
2908 
2909     // same_locals_1_stack_item_frame_extended {
2910     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2911     //   u2 offset_delta;
2912     //   verification_type_info stack[1];
2913     // }
2914     else if (frame_type == 247) {
2915       stackmap_p += 2;
2916       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2917         calc_number_of_entries, frame_type, THREAD);
2918     }
2919 
2920     // chop_frame {
2921     //   u1 frame_type = CHOP; /* 248-250 */
2922     //   u2 offset_delta;
2923     // }
2924     else if (frame_type >= 248 && frame_type <= 250) {
2925       stackmap_p += 2;
2926     }
2927 
2928     // same_frame_extended {
2929     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2930     //   u2 offset_delta;
2931     // }
2932     else if (frame_type == 251) {
2933       stackmap_p += 2;
2934     }
2935 
2936     // append_frame {
2937     //   u1 frame_type = APPEND; /* 252-254 */
2938     //   u2 offset_delta;
2939     //   verification_type_info locals[frame_type - 251];
2940     // }
2941     else if (frame_type >= 252 && frame_type <= 254) {
2942       assert(stackmap_p + 2 <= stackmap_end,
2943         "no room for offset_delta");
2944       stackmap_p += 2;
2945       u1 len = frame_type - 251;
2946       for (u1 i = 0; i < len; i++) {
2947         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2948           calc_number_of_entries, frame_type, THREAD);
2949       }
2950     }
2951 
2952     // full_frame {
2953     //   u1 frame_type = FULL_FRAME; /* 255 */
2954     //   u2 offset_delta;
2955     //   u2 number_of_locals;
2956     //   verification_type_info locals[number_of_locals];
2957     //   u2 number_of_stack_items;
2958     //   verification_type_info stack[number_of_stack_items];
2959     // }
2960     else if (frame_type == 255) {
2961       assert(stackmap_p + 2 + 2 <= stackmap_end,
2962         "no room for smallest full_frame");
2963       stackmap_p += 2;
2964 
2965       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2966       stackmap_p += 2;
2967 
2968       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2969         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2970           calc_number_of_entries, frame_type, THREAD);
2971       }
2972 
2973       // Use the largest size for the number_of_stack_items, but only get
2974       // the right number of bytes.
2975       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2976       stackmap_p += 2;
2977 
2978       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2979         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2980           calc_number_of_entries, frame_type, THREAD);
2981       }
2982     }
2983   } // end while there is a stack_map_frame
2984   assert(number_of_entries == calc_number_of_entries, "sanity check");
2985 } // end rewrite_cp_refs_in_stack_map_table()
2986 
2987 
2988 // Rewrite constant pool references in the verification type info
2989 // portion of the method's stackmap table. These "structures" are
2990 // adapted from the StackMapTable_attribute that is described in
2991 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2992 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2993 //
2994 // The verification_type_info structure is a u1 tag followed by 0 or
2995 // more bytes of data:
2996 //
2997 // union verification_type_info {
2998 //   Top_variable_info;
2999 //   Integer_variable_info;
3000 //   Float_variable_info;
3001 //   Long_variable_info;
3002 //   Double_variable_info;
3003 //   Null_variable_info;
3004 //   UninitializedThis_variable_info;
3005 //   Object_variable_info;
3006 //   Uninitialized_variable_info;
3007 // }
3008 //
3009 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3010        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3011        u1 frame_type, TRAPS) {
3012 
3013   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3014   u1 tag = *stackmap_p_ref;
3015   stackmap_p_ref++;
3016 
3017   switch (tag) {
3018   // Top_variable_info {
3019   //   u1 tag = ITEM_Top; /* 0 */
3020   // }
3021   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3022   case 0:  // fall through
3023 
3024   // Integer_variable_info {
3025   //   u1 tag = ITEM_Integer; /* 1 */
3026   // }
3027   case ITEM_Integer:  // fall through
3028 
3029   // Float_variable_info {
3030   //   u1 tag = ITEM_Float; /* 2 */
3031   // }
3032   case ITEM_Float:  // fall through
3033 
3034   // Double_variable_info {
3035   //   u1 tag = ITEM_Double; /* 3 */
3036   // }
3037   case ITEM_Double:  // fall through
3038 
3039   // Long_variable_info {
3040   //   u1 tag = ITEM_Long; /* 4 */
3041   // }
3042   case ITEM_Long:  // fall through
3043 
3044   // Null_variable_info {
3045   //   u1 tag = ITEM_Null; /* 5 */
3046   // }
3047   case ITEM_Null:  // fall through
3048 
3049   // UninitializedThis_variable_info {
3050   //   u1 tag = ITEM_UninitializedThis; /* 6 */
3051   // }
3052   case ITEM_UninitializedThis:
3053     // nothing more to do for the above tag types
3054     break;
3055 
3056   // Object_variable_info {
3057   //   u1 tag = ITEM_Object; /* 7 */
3058   //   u2 cpool_index;
3059   // }
3060   case ITEM_Object:
3061   {
3062     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3063     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3064     u2 new_cp_index = find_new_index(cpool_index);
3065     if (new_cp_index != 0) {
3066       log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3067       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3068       cpool_index = new_cp_index;
3069     }
3070     stackmap_p_ref += 2;
3071 
3072     log_debug(redefine, class, stackmap)
3073       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3074   } break;
3075 
3076   // Uninitialized_variable_info {
3077   //   u1 tag = ITEM_Uninitialized; /* 8 */
3078   //   u2 offset;
3079   // }
3080   case ITEM_Uninitialized:
3081     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3082     stackmap_p_ref += 2;
3083     break;
3084 
3085   default:
3086     log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3087     ShouldNotReachHere();
3088     break;
3089   } // end switch (tag)
3090 } // end rewrite_cp_refs_in_verification_type_info()
3091 
3092 
3093 // Change the constant pool associated with klass scratch_class to
3094 // scratch_cp. If shrink is true, then scratch_cp_length elements
3095 // are copied from scratch_cp to a smaller constant pool and the
3096 // smaller constant pool is associated with scratch_class.
3097 void VM_RedefineClasses::set_new_constant_pool(
3098        ClassLoaderData* loader_data,
3099        InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3100        int scratch_cp_length, TRAPS) {
3101   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3102 
3103   // scratch_cp is a merged constant pool and has enough space for a
3104   // worst case merge situation. We want to associate the minimum
3105   // sized constant pool with the klass to save space.
3106   ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3107   constantPoolHandle smaller_cp(THREAD, cp);
3108 
3109   // preserve version() value in the smaller copy
3110   int version = scratch_cp->version();
3111   assert(version != 0, "sanity check");
3112   smaller_cp->set_version(version);
3113 
3114   // attach klass to new constant pool
3115   // reference to the cp holder is needed for copy_operands()
3116   smaller_cp->set_pool_holder(scratch_class);
3117 
3118   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3119   if (HAS_PENDING_EXCEPTION) {
3120     // Exception is handled in the caller
3121     loader_data->add_to_deallocate_list(smaller_cp());
3122     return;
3123   }
3124   scratch_cp = smaller_cp;
3125 
3126   // attach new constant pool to klass
3127   scratch_class->set_constants(scratch_cp());
3128   scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3129 
3130   int i;  // for portability
3131 
3132   // update each field in klass to use new constant pool indices as needed
3133   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3134     jshort cur_index = fs.name_index();
3135     jshort new_index = find_new_index(cur_index);
3136     if (new_index != 0) {
3137       log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3138       fs.set_name_index(new_index);
3139     }
3140     cur_index = fs.signature_index();
3141     new_index = find_new_index(cur_index);
3142     if (new_index != 0) {
3143       log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3144       fs.set_signature_index(new_index);
3145     }
3146     cur_index = fs.initval_index();
3147     new_index = find_new_index(cur_index);
3148     if (new_index != 0) {
3149       log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3150       fs.set_initval_index(new_index);
3151     }
3152     cur_index = fs.generic_signature_index();
3153     new_index = find_new_index(cur_index);
3154     if (new_index != 0) {
3155       log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3156       fs.set_generic_signature_index(new_index);
3157     }
3158   } // end for each field
3159 
3160   // Update constant pool indices in the inner classes info to use
3161   // new constant indices as needed. The inner classes info is a
3162   // quadruple:
3163   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3164   InnerClassesIterator iter(scratch_class);
3165   for (; !iter.done(); iter.next()) {
3166     int cur_index = iter.inner_class_info_index();
3167     if (cur_index == 0) {
3168       continue;  // JVM spec. allows null inner class refs so skip it
3169     }
3170     int new_index = find_new_index(cur_index);
3171     if (new_index != 0) {
3172       log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3173       iter.set_inner_class_info_index(new_index);
3174     }
3175     cur_index = iter.outer_class_info_index();
3176     new_index = find_new_index(cur_index);
3177     if (new_index != 0) {
3178       log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3179       iter.set_outer_class_info_index(new_index);
3180     }
3181     cur_index = iter.inner_name_index();
3182     new_index = find_new_index(cur_index);
3183     if (new_index != 0) {
3184       log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3185       iter.set_inner_name_index(new_index);
3186     }
3187   } // end for each inner class
3188 
3189   // Attach each method in klass to the new constant pool and update
3190   // to use new constant pool indices as needed:
3191   Array<Method*>* methods = scratch_class->methods();
3192   for (i = methods->length() - 1; i >= 0; i--) {
3193     methodHandle method(THREAD, methods->at(i));
3194     method->set_constants(scratch_cp());
3195 
3196     int new_index = find_new_index(method->name_index());
3197     if (new_index != 0) {
3198       log_trace(redefine, class, constantpool)
3199         ("method-name_index change: %d to %d", method->name_index(), new_index);
3200       method->set_name_index(new_index);
3201     }
3202     new_index = find_new_index(method->signature_index());
3203     if (new_index != 0) {
3204       log_trace(redefine, class, constantpool)
3205         ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3206       method->set_signature_index(new_index);
3207     }
3208     new_index = find_new_index(method->generic_signature_index());
3209     if (new_index != 0) {
3210       log_trace(redefine, class, constantpool)
3211         ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3212       method->set_generic_signature_index(new_index);
3213     }
3214 
3215     // Update constant pool indices in the method's checked exception
3216     // table to use new constant indices as needed.
3217     int cext_length = method->checked_exceptions_length();
3218     if (cext_length > 0) {
3219       CheckedExceptionElement * cext_table =
3220         method->checked_exceptions_start();
3221       for (int j = 0; j < cext_length; j++) {
3222         int cur_index = cext_table[j].class_cp_index;
3223         int new_index = find_new_index(cur_index);
3224         if (new_index != 0) {
3225           log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3226           cext_table[j].class_cp_index = (u2)new_index;
3227         }
3228       } // end for each checked exception table entry
3229     } // end if there are checked exception table entries
3230 
3231     // Update each catch type index in the method's exception table
3232     // to use new constant pool indices as needed. The exception table
3233     // holds quadruple entries of the form:
3234     //   (beg_bci, end_bci, handler_bci, klass_index)
3235 
3236     ExceptionTable ex_table(method());
3237     int ext_length = ex_table.length();
3238 
3239     for (int j = 0; j < ext_length; j ++) {
3240       int cur_index = ex_table.catch_type_index(j);
3241       int new_index = find_new_index(cur_index);
3242       if (new_index != 0) {
3243         log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3244         ex_table.set_catch_type_index(j, new_index);
3245       }
3246     } // end for each exception table entry
3247 
3248     // Update constant pool indices in the method's local variable
3249     // table to use new constant indices as needed. The local variable
3250     // table hold sextuple entries of the form:
3251     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3252     int lvt_length = method->localvariable_table_length();
3253     if (lvt_length > 0) {
3254       LocalVariableTableElement * lv_table =
3255         method->localvariable_table_start();
3256       for (int j = 0; j < lvt_length; j++) {
3257         int cur_index = lv_table[j].name_cp_index;
3258         int new_index = find_new_index(cur_index);
3259         if (new_index != 0) {
3260           log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3261           lv_table[j].name_cp_index = (u2)new_index;
3262         }
3263         cur_index = lv_table[j].descriptor_cp_index;
3264         new_index = find_new_index(cur_index);
3265         if (new_index != 0) {
3266           log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3267           lv_table[j].descriptor_cp_index = (u2)new_index;
3268         }
3269         cur_index = lv_table[j].signature_cp_index;
3270         new_index = find_new_index(cur_index);
3271         if (new_index != 0) {
3272           log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3273           lv_table[j].signature_cp_index = (u2)new_index;
3274         }
3275       } // end for each local variable table entry
3276     } // end if there are local variable table entries
3277 
3278     rewrite_cp_refs_in_stack_map_table(method, THREAD);
3279   } // end for each method
3280 } // end set_new_constant_pool()
3281 
3282 
3283 // Unevolving classes may point to methods of the_class directly
3284 // from their constant pool caches, itables, and/or vtables. We
3285 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3286 // to fix up these pointers.
3287 
3288 // Adjust cpools and vtables closure
3289 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3290 
3291   // This is a very busy routine. We don't want too much tracing
3292   // printed out.
3293   bool trace_name_printed = false;
3294   InstanceKlass *the_class = InstanceKlass::cast(_the_class);
3295 
3296   // If the class being redefined is java.lang.Object, we need to fix all
3297   // array class vtables also
3298   if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) {
3299     k->vtable().adjust_method_entries(the_class, &trace_name_printed);
3300 
3301   } else if (k->is_instance_klass()) {
3302     HandleMark hm(_thread);
3303     InstanceKlass *ik = InstanceKlass::cast(k);
3304 
3305     // HotSpot specific optimization! HotSpot does not currently
3306     // support delegation from the bootstrap class loader to a
3307     // user-defined class loader. This means that if the bootstrap
3308     // class loader is the initiating class loader, then it will also
3309     // be the defining class loader. This also means that classes
3310     // loaded by the bootstrap class loader cannot refer to classes
3311     // loaded by a user-defined class loader. Note: a user-defined
3312     // class loader can delegate to the bootstrap class loader.
3313     //
3314     // If the current class being redefined has a user-defined class
3315     // loader as its defining class loader, then we can skip all
3316     // classes loaded by the bootstrap class loader.
3317     bool is_user_defined = (_the_class->class_loader() != NULL);
3318     if (is_user_defined && ik->class_loader() == NULL) {
3319       return;
3320     }
3321 
3322     // Fix the vtable embedded in the_class and subclasses of the_class,
3323     // if one exists. We discard scratch_class and we don't keep an
3324     // InstanceKlass around to hold obsolete methods so we don't have
3325     // any other InstanceKlass embedded vtables to update. The vtable
3326     // holds the Method*s for virtual (but not final) methods.
3327     // Default methods, or concrete methods in interfaces are stored
3328     // in the vtable, so if an interface changes we need to check
3329     // adjust_method_entries() for every InstanceKlass, which will also
3330     // adjust the default method vtable indices.
3331     // We also need to adjust any default method entries that are
3332     // not yet in the vtable, because the vtable setup is in progress.
3333     // This must be done after we adjust the default_methods and
3334     // default_vtable_indices for methods already in the vtable.
3335     // If redefining Unsafe, walk all the vtables looking for entries.
3336     if (ik->vtable_length() > 0 && (_the_class->is_interface()
3337         || _the_class == SystemDictionary::internal_Unsafe_klass()
3338         || ik->is_subtype_of(_the_class))) {
3339       // ik->vtable() creates a wrapper object; rm cleans it up
3340       ResourceMark rm(_thread);
3341 
3342       ik->vtable().adjust_method_entries(the_class, &trace_name_printed);
3343       ik->adjust_default_methods(the_class, &trace_name_printed);
3344     }
3345 
3346     // If the current class has an itable and we are either redefining an
3347     // interface or if the current class is a subclass of the_class, then
3348     // we potentially have to fix the itable. If we are redefining an
3349     // interface, then we have to call adjust_method_entries() for
3350     // every InstanceKlass that has an itable since there isn't a
3351     // subclass relationship between an interface and an InstanceKlass.
3352     // If redefining Unsafe, walk all the itables looking for entries.
3353     if (ik->itable_length() > 0 && (_the_class->is_interface()
3354         || _the_class == SystemDictionary::internal_Unsafe_klass()
3355         || ik->is_subclass_of(_the_class))) {
3356       ResourceMark rm(_thread);
3357       ik->itable().adjust_method_entries(the_class, &trace_name_printed);
3358     }
3359 
3360     // The constant pools in other classes (other_cp) can refer to
3361     // methods in the_class. We have to update method information in
3362     // other_cp's cache. If other_cp has a previous version, then we
3363     // have to repeat the process for each previous version. The
3364     // constant pool cache holds the Method*s for non-virtual
3365     // methods and for virtual, final methods.
3366     //
3367     // Special case: if the current class is the_class, then new_cp
3368     // has already been attached to the_class and old_cp has already
3369     // been added as a previous version. The new_cp doesn't have any
3370     // cached references to old methods so it doesn't need to be
3371     // updated. We can simply start with the previous version(s) in
3372     // that case.
3373     constantPoolHandle other_cp;
3374     ConstantPoolCache* cp_cache;
3375 
3376     if (ik != _the_class) {
3377       // this klass' constant pool cache may need adjustment
3378       other_cp = constantPoolHandle(ik->constants());
3379       cp_cache = other_cp->cache();
3380       if (cp_cache != NULL) {
3381         cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3382       }
3383     }
3384 
3385     // the previous versions' constant pool caches may need adjustment
3386     for (InstanceKlass* pv_node = ik->previous_versions();
3387          pv_node != NULL;
3388          pv_node = pv_node->previous_versions()) {
3389       cp_cache = pv_node->constants()->cache();
3390       if (cp_cache != NULL) {
3391         cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3392       }
3393     }
3394   }
3395 }
3396 
3397 // Clean method data for this class
3398 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3399   if (k->is_instance_klass()) {
3400     InstanceKlass *ik = InstanceKlass::cast(k);
3401     // Clean MethodData of this class's methods so they don't refer to
3402     // old methods that are no longer running.
3403     Array<Method*>* methods = ik->methods();
3404     int num_methods = methods->length();
3405     for (int index = 0; index < num_methods; ++index) {
3406       if (methods->at(index)->method_data() != NULL) {
3407         methods->at(index)->method_data()->clean_weak_method_links();
3408       }
3409     }
3410   }
3411 }
3412 
3413 void VM_RedefineClasses::update_jmethod_ids() {
3414   for (int j = 0; j < _matching_methods_length; ++j) {
3415     Method* old_method = _matching_old_methods[j];
3416     jmethodID jmid = old_method->find_jmethod_id_or_null();
3417     if (jmid != NULL) {
3418       // There is a jmethodID, change it to point to the new method
3419       methodHandle new_method_h(_matching_new_methods[j]);
3420       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3421       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3422              "should be replaced");
3423     }
3424   }
3425 }
3426 
3427 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3428   int emcp_method_count = 0;
3429   int obsolete_count = 0;
3430   int old_index = 0;
3431   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3432     Method* old_method = _matching_old_methods[j];
3433     Method* new_method = _matching_new_methods[j];
3434     Method* old_array_method;
3435 
3436     // Maintain an old_index into the _old_methods array by skipping
3437     // deleted methods
3438     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3439       ++old_index;
3440     }
3441 
3442     if (MethodComparator::methods_EMCP(old_method, new_method)) {
3443       // The EMCP definition from JSR-163 requires the bytecodes to be
3444       // the same with the exception of constant pool indices which may
3445       // differ. However, the constants referred to by those indices
3446       // must be the same.
3447       //
3448       // We use methods_EMCP() for comparison since constant pool
3449       // merging can remove duplicate constant pool entries that were
3450       // present in the old method and removed from the rewritten new
3451       // method. A faster binary comparison function would consider the
3452       // old and new methods to be different when they are actually
3453       // EMCP.
3454       //
3455       // The old and new methods are EMCP and you would think that we
3456       // could get rid of one of them here and now and save some space.
3457       // However, the concept of EMCP only considers the bytecodes and
3458       // the constant pool entries in the comparison. Other things,
3459       // e.g., the line number table (LNT) or the local variable table
3460       // (LVT) don't count in the comparison. So the new (and EMCP)
3461       // method can have a new LNT that we need so we can't just
3462       // overwrite the new method with the old method.
3463       //
3464       // When this routine is called, we have already attached the new
3465       // methods to the_class so the old methods are effectively
3466       // overwritten. However, if an old method is still executing,
3467       // then the old method cannot be collected until sometime after
3468       // the old method call has returned. So the overwriting of old
3469       // methods by new methods will save us space except for those
3470       // (hopefully few) old methods that are still executing.
3471       //
3472       // A method refers to a ConstMethod* and this presents another
3473       // possible avenue to space savings. The ConstMethod* in the
3474       // new method contains possibly new attributes (LNT, LVT, etc).
3475       // At first glance, it seems possible to save space by replacing
3476       // the ConstMethod* in the old method with the ConstMethod*
3477       // from the new method. The old and new methods would share the
3478       // same ConstMethod* and we would save the space occupied by
3479       // the old ConstMethod*. However, the ConstMethod* contains
3480       // a back reference to the containing method. Sharing the
3481       // ConstMethod* between two methods could lead to confusion in
3482       // the code that uses the back reference. This would lead to
3483       // brittle code that could be broken in non-obvious ways now or
3484       // in the future.
3485       //
3486       // Another possibility is to copy the ConstMethod* from the new
3487       // method to the old method and then overwrite the new method with
3488       // the old method. Since the ConstMethod* contains the bytecodes
3489       // for the method embedded in the oop, this option would change
3490       // the bytecodes out from under any threads executing the old
3491       // method and make the thread's bcp invalid. Since EMCP requires
3492       // that the bytecodes be the same modulo constant pool indices, it
3493       // is straight forward to compute the correct new bcp in the new
3494       // ConstMethod* from the old bcp in the old ConstMethod*. The
3495       // time consuming part would be searching all the frames in all
3496       // of the threads to find all of the calls to the old method.
3497       //
3498       // It looks like we will have to live with the limited savings
3499       // that we get from effectively overwriting the old methods
3500       // when the new methods are attached to the_class.
3501 
3502       // Count number of methods that are EMCP.  The method will be marked
3503       // old but not obsolete if it is EMCP.
3504       emcp_method_count++;
3505 
3506       // An EMCP method is _not_ obsolete. An obsolete method has a
3507       // different jmethodID than the current method. An EMCP method
3508       // has the same jmethodID as the current method. Having the
3509       // same jmethodID for all EMCP versions of a method allows for
3510       // a consistent view of the EMCP methods regardless of which
3511       // EMCP method you happen to have in hand. For example, a
3512       // breakpoint set in one EMCP method will work for all EMCP
3513       // versions of the method including the current one.
3514     } else {
3515       // mark obsolete methods as such
3516       old_method->set_is_obsolete();
3517       obsolete_count++;
3518 
3519       // obsolete methods need a unique idnum so they become new entries in
3520       // the jmethodID cache in InstanceKlass
3521       assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3522       u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3523       if (num != ConstMethod::UNSET_IDNUM) {
3524         old_method->set_method_idnum(num);
3525       }
3526 
3527       // With tracing we try not to "yack" too much. The position of
3528       // this trace assumes there are fewer obsolete methods than
3529       // EMCP methods.
3530       if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3531         ResourceMark rm;
3532         log_trace(redefine, class, obsolete, mark)
3533           ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3534       }
3535     }
3536     old_method->set_is_old();
3537   }
3538   for (int i = 0; i < _deleted_methods_length; ++i) {
3539     Method* old_method = _deleted_methods[i];
3540 
3541     assert(!old_method->has_vtable_index(),
3542            "cannot delete methods with vtable entries");;
3543 
3544     // Mark all deleted methods as old, obsolete and deleted
3545     old_method->set_is_deleted();
3546     old_method->set_is_old();
3547     old_method->set_is_obsolete();
3548     ++obsolete_count;
3549     // With tracing we try not to "yack" too much. The position of
3550     // this trace assumes there are fewer obsolete methods than
3551     // EMCP methods.
3552     if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3553       ResourceMark rm;
3554       log_trace(redefine, class, obsolete, mark)
3555         ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3556     }
3557   }
3558   assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3559     "sanity check");
3560   log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3561   return emcp_method_count;
3562 }
3563 
3564 // This internal class transfers the native function registration from old methods
3565 // to new methods.  It is designed to handle both the simple case of unchanged
3566 // native methods and the complex cases of native method prefixes being added and/or
3567 // removed.
3568 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3569 //
3570 // This class is used after the new methods have been installed in "the_class".
3571 //
3572 // So, for example, the following must be handled.  Where 'm' is a method and
3573 // a number followed by an underscore is a prefix.
3574 //
3575 //                                      Old Name    New Name
3576 // Simple transfer to new method        m       ->  m
3577 // Add prefix                           m       ->  1_m
3578 // Remove prefix                        1_m     ->  m
3579 // Simultaneous add of prefixes         m       ->  3_2_1_m
3580 // Simultaneous removal of prefixes     3_2_1_m ->  m
3581 // Simultaneous add and remove          1_m     ->  2_m
3582 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
3583 //
3584 class TransferNativeFunctionRegistration {
3585  private:
3586   InstanceKlass* the_class;
3587   int prefix_count;
3588   char** prefixes;
3589 
3590   // Recursively search the binary tree of possibly prefixed method names.
3591   // Iteration could be used if all agents were well behaved. Full tree walk is
3592   // more resilent to agents not cleaning up intermediate methods.
3593   // Branch at each depth in the binary tree is:
3594   //    (1) without the prefix.
3595   //    (2) with the prefix.
3596   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3597   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3598                                      Symbol* signature) {
3599     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3600     if (name_symbol != NULL) {
3601       Method* method = the_class->lookup_method(name_symbol, signature);
3602       if (method != NULL) {
3603         // Even if prefixed, intermediate methods must exist.
3604         if (method->is_native()) {
3605           // Wahoo, we found a (possibly prefixed) version of the method, return it.
3606           return method;
3607         }
3608         if (depth < prefix_count) {
3609           // Try applying further prefixes (other than this one).
3610           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3611           if (method != NULL) {
3612             return method; // found
3613           }
3614 
3615           // Try adding this prefix to the method name and see if it matches
3616           // another method name.
3617           char* prefix = prefixes[depth];
3618           size_t prefix_len = strlen(prefix);
3619           size_t trial_len = name_len + prefix_len;
3620           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3621           strcpy(trial_name_str, prefix);
3622           strcat(trial_name_str, name_str);
3623           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3624                                             signature);
3625           if (method != NULL) {
3626             // If found along this branch, it was prefixed, mark as such
3627             method->set_is_prefixed_native();
3628             return method; // found
3629           }
3630         }
3631       }
3632     }
3633     return NULL;  // This whole branch bore nothing
3634   }
3635 
3636   // Return the method name with old prefixes stripped away.
3637   char* method_name_without_prefixes(Method* method) {
3638     Symbol* name = method->name();
3639     char* name_str = name->as_utf8();
3640 
3641     // Old prefixing may be defunct, strip prefixes, if any.
3642     for (int i = prefix_count-1; i >= 0; i--) {
3643       char* prefix = prefixes[i];
3644       size_t prefix_len = strlen(prefix);
3645       if (strncmp(prefix, name_str, prefix_len) == 0) {
3646         name_str += prefix_len;
3647       }
3648     }
3649     return name_str;
3650   }
3651 
3652   // Strip any prefixes off the old native method, then try to find a
3653   // (possibly prefixed) new native that matches it.
3654   Method* strip_and_search_for_new_native(Method* method) {
3655     ResourceMark rm;
3656     char* name_str = method_name_without_prefixes(method);
3657     return search_prefix_name_space(0, name_str, strlen(name_str),
3658                                     method->signature());
3659   }
3660 
3661  public:
3662 
3663   // Construct a native method transfer processor for this class.
3664   TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3665     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3666 
3667     the_class = _the_class;
3668     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3669   }
3670 
3671   // Attempt to transfer any of the old or deleted methods that are native
3672   void transfer_registrations(Method** old_methods, int methods_length) {
3673     for (int j = 0; j < methods_length; j++) {
3674       Method* old_method = old_methods[j];
3675 
3676       if (old_method->is_native() && old_method->has_native_function()) {
3677         Method* new_method = strip_and_search_for_new_native(old_method);
3678         if (new_method != NULL) {
3679           // Actually set the native function in the new method.
3680           // Redefine does not send events (except CFLH), certainly not this
3681           // behind the scenes re-registration.
3682           new_method->set_native_function(old_method->native_function(),
3683                               !Method::native_bind_event_is_interesting);
3684         }
3685       }
3686     }
3687   }
3688 };
3689 
3690 // Don't lose the association between a native method and its JNI function.
3691 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3692   TransferNativeFunctionRegistration transfer(the_class);
3693   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3694   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3695 }
3696 
3697 // Deoptimize all compiled code that depends on this class.
3698 //
3699 // If the can_redefine_classes capability is obtained in the onload
3700 // phase then the compiler has recorded all dependencies from startup.
3701 // In that case we need only deoptimize and throw away all compiled code
3702 // that depends on the class.
3703 //
3704 // If can_redefine_classes is obtained sometime after the onload
3705 // phase then the dependency information may be incomplete. In that case
3706 // the first call to RedefineClasses causes all compiled code to be
3707 // thrown away. As can_redefine_classes has been obtained then
3708 // all future compilations will record dependencies so second and
3709 // subsequent calls to RedefineClasses need only throw away code
3710 // that depends on the class.
3711 //
3712 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) {
3713   assert_locked_or_safepoint(Compile_lock);
3714 
3715   // All dependencies have been recorded from startup or this is a second or
3716   // subsequent use of RedefineClasses
3717   if (JvmtiExport::all_dependencies_are_recorded()) {
3718     CodeCache::flush_evol_dependents_on(ik);
3719   } else {
3720     CodeCache::mark_all_nmethods_for_deoptimization();
3721 
3722     ResourceMark rm(THREAD);
3723     DeoptimizationMarker dm;
3724 
3725     // Deoptimize all activations depending on marked nmethods
3726     Deoptimization::deoptimize_dependents();
3727 
3728     // Make the dependent methods not entrant
3729     CodeCache::make_marked_nmethods_not_entrant();
3730 
3731     // From now on we know that the dependency information is complete
3732     JvmtiExport::set_all_dependencies_are_recorded(true);
3733   }
3734 }
3735 
3736 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3737   Method* old_method;
3738   Method* new_method;
3739 
3740   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3741   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3742   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3743   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3744 
3745   _matching_methods_length = 0;
3746   _deleted_methods_length  = 0;
3747   _added_methods_length    = 0;
3748 
3749   int nj = 0;
3750   int oj = 0;
3751   while (true) {
3752     if (oj >= _old_methods->length()) {
3753       if (nj >= _new_methods->length()) {
3754         break; // we've looked at everything, done
3755       }
3756       // New method at the end
3757       new_method = _new_methods->at(nj);
3758       _added_methods[_added_methods_length++] = new_method;
3759       ++nj;
3760     } else if (nj >= _new_methods->length()) {
3761       // Old method, at the end, is deleted
3762       old_method = _old_methods->at(oj);
3763       _deleted_methods[_deleted_methods_length++] = old_method;
3764       ++oj;
3765     } else {
3766       old_method = _old_methods->at(oj);
3767       new_method = _new_methods->at(nj);
3768       if (old_method->name() == new_method->name()) {
3769         if (old_method->signature() == new_method->signature()) {
3770           _matching_old_methods[_matching_methods_length  ] = old_method;
3771           _matching_new_methods[_matching_methods_length++] = new_method;
3772           ++nj;
3773           ++oj;
3774         } else {
3775           // added overloaded have already been moved to the end,
3776           // so this is a deleted overloaded method
3777           _deleted_methods[_deleted_methods_length++] = old_method;
3778           ++oj;
3779         }
3780       } else { // names don't match
3781         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3782           // new method
3783           _added_methods[_added_methods_length++] = new_method;
3784           ++nj;
3785         } else {
3786           // deleted method
3787           _deleted_methods[_deleted_methods_length++] = old_method;
3788           ++oj;
3789         }
3790       }
3791     }
3792   }
3793   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3794   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3795 }
3796 
3797 
3798 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
3799                                           InstanceKlass* scratch_class) {
3800   // Swap annotation fields values
3801   Annotations* old_annotations = the_class->annotations();
3802   the_class->set_annotations(scratch_class->annotations());
3803   scratch_class->set_annotations(old_annotations);
3804 }
3805 
3806 
3807 // Install the redefinition of a class:
3808 //    - house keeping (flushing breakpoints and caches, deoptimizing
3809 //      dependent compiled code)
3810 //    - replacing parts in the_class with parts from scratch_class
3811 //    - adding a weak reference to track the obsolete but interesting
3812 //      parts of the_class
3813 //    - adjusting constant pool caches and vtables in other classes
3814 //      that refer to methods in the_class. These adjustments use the
3815 //      ClassLoaderDataGraph::classes_do() facility which only allows
3816 //      a helper method to be specified. The interesting parameters
3817 //      that we would like to pass to the helper method are saved in
3818 //      static global fields in the VM operation.
3819 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3820        InstanceKlass* scratch_class, TRAPS) {
3821 
3822   HandleMark hm(THREAD);   // make sure handles from this call are freed
3823 
3824   if (log_is_enabled(Info, redefine, class, timer)) {
3825     _timer_rsc_phase1.start();
3826   }
3827 
3828   InstanceKlass* the_class = get_ik(the_jclass);
3829 
3830   // Remove all breakpoints in methods of this class
3831   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3832   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
3833 
3834   // Deoptimize all compiled code that depends on this class
3835   flush_dependent_code(the_class, THREAD);
3836 
3837   _old_methods = the_class->methods();
3838   _new_methods = scratch_class->methods();
3839   _the_class = the_class;
3840   compute_added_deleted_matching_methods();
3841   update_jmethod_ids();
3842 
3843   _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
3844 
3845   // Attach new constant pool to the original klass. The original
3846   // klass still refers to the old constant pool (for now).
3847   scratch_class->constants()->set_pool_holder(the_class);
3848 
3849 #if 0
3850   // In theory, with constant pool merging in place we should be able
3851   // to save space by using the new, merged constant pool in place of
3852   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3853   // the klass version we are replacing now and any constant pool(s) in
3854   // previous versions of klass. Nice theory, doesn't work in practice.
3855   // When this code is enabled, even simple programs throw NullPointer
3856   // exceptions. I'm guessing that this is caused by some constant pool
3857   // cache difference between the new, merged constant pool and the
3858   // constant pool that was just being used by the klass. I'm keeping
3859   // this code around to archive the idea, but the code has to remain
3860   // disabled for now.
3861 
3862   // Attach each old method to the new constant pool. This can be
3863   // done here since we are past the bytecode verification and
3864   // constant pool optimization phases.
3865   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3866     Method* method = _old_methods->at(i);
3867     method->set_constants(scratch_class->constants());
3868   }
3869 
3870   // NOTE: this doesn't work because you can redefine the same class in two
3871   // threads, each getting their own constant pool data appended to the
3872   // original constant pool.  In order for the new methods to work when they
3873   // become old methods, they need to keep their updated copy of the constant pool.
3874 
3875   {
3876     // walk all previous versions of the klass
3877     InstanceKlass *ik = the_class;
3878     PreviousVersionWalker pvw(ik);
3879     do {
3880       ik = pvw.next_previous_version();
3881       if (ik != NULL) {
3882 
3883         // attach previous version of klass to the new constant pool
3884         ik->set_constants(scratch_class->constants());
3885 
3886         // Attach each method in the previous version of klass to the
3887         // new constant pool
3888         Array<Method*>* prev_methods = ik->methods();
3889         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3890           Method* method = prev_methods->at(i);
3891           method->set_constants(scratch_class->constants());
3892         }
3893       }
3894     } while (ik != NULL);
3895   }
3896 #endif
3897 
3898   // Replace methods and constantpool
3899   the_class->set_methods(_new_methods);
3900   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3901                                           // and to be able to undo operation easily.
3902 
3903   Array<int>* old_ordering = the_class->method_ordering();
3904   the_class->set_method_ordering(scratch_class->method_ordering());
3905   scratch_class->set_method_ordering(old_ordering);
3906 
3907   ConstantPool* old_constants = the_class->constants();
3908   the_class->set_constants(scratch_class->constants());
3909   scratch_class->set_constants(old_constants);  // See the previous comment.
3910 #if 0
3911   // We are swapping the guts of "the new class" with the guts of "the
3912   // class". Since the old constant pool has just been attached to "the
3913   // new class", it seems logical to set the pool holder in the old
3914   // constant pool also. However, doing this will change the observable
3915   // class hierarchy for any old methods that are still executing. A
3916   // method can query the identity of its "holder" and this query uses
3917   // the method's constant pool link to find the holder. The change in
3918   // holding class from "the class" to "the new class" can confuse
3919   // things.
3920   //
3921   // Setting the old constant pool's holder will also cause
3922   // verification done during vtable initialization below to fail.
3923   // During vtable initialization, the vtable's class is verified to be
3924   // a subtype of the method's holder. The vtable's class is "the
3925   // class" and the method's holder is gotten from the constant pool
3926   // link in the method itself. For "the class"'s directly implemented
3927   // methods, the method holder is "the class" itself (as gotten from
3928   // the new constant pool). The check works fine in this case. The
3929   // check also works fine for methods inherited from super classes.
3930   //
3931   // Miranda methods are a little more complicated. A miranda method is
3932   // provided by an interface when the class implementing the interface
3933   // does not provide its own method.  These interfaces are implemented
3934   // internally as an InstanceKlass. These special instanceKlasses
3935   // share the constant pool of the class that "implements" the
3936   // interface. By sharing the constant pool, the method holder of a
3937   // miranda method is the class that "implements" the interface. In a
3938   // non-redefine situation, the subtype check works fine. However, if
3939   // the old constant pool's pool holder is modified, then the check
3940   // fails because there is no class hierarchy relationship between the
3941   // vtable's class and "the new class".
3942 
3943   old_constants->set_pool_holder(scratch_class());
3944 #endif
3945 
3946   // track number of methods that are EMCP for add_previous_version() call below
3947   int emcp_method_count = check_methods_and_mark_as_obsolete();
3948   transfer_old_native_function_registrations(the_class);
3949 
3950   // The class file bytes from before any retransformable agents mucked
3951   // with them was cached on the scratch class, move to the_class.
3952   // Note: we still want to do this if nothing needed caching since it
3953   // should get cleared in the_class too.
3954   if (the_class->get_cached_class_file() == 0) {
3955     // the_class doesn't have a cache yet so copy it
3956     the_class->set_cached_class_file(scratch_class->get_cached_class_file());
3957   }
3958   else if (scratch_class->get_cached_class_file() !=
3959            the_class->get_cached_class_file()) {
3960     // The same class can be present twice in the scratch classes list or there
3961     // are multiple concurrent RetransformClasses calls on different threads.
3962     // In such cases we have to deallocate scratch_class cached_class_file.
3963     os::free(scratch_class->get_cached_class_file());
3964   }
3965 
3966   // NULL out in scratch class to not delete twice.  The class to be redefined
3967   // always owns these bytes.
3968   scratch_class->set_cached_class_file(NULL);
3969 
3970   // Replace inner_classes
3971   Array<u2>* old_inner_classes = the_class->inner_classes();
3972   the_class->set_inner_classes(scratch_class->inner_classes());
3973   scratch_class->set_inner_classes(old_inner_classes);
3974 
3975   // Initialize the vtable and interface table after
3976   // methods have been rewritten
3977   {
3978     ResourceMark rm(THREAD);
3979     // no exception should happen here since we explicitly
3980     // do not check loader constraints.
3981     // compare_and_normalize_class_versions has already checked:
3982     //  - classloaders unchanged, signatures unchanged
3983     //  - all instanceKlasses for redefined classes reused & contents updated
3984     the_class->vtable().initialize_vtable(false, THREAD);
3985     the_class->itable().initialize_itable(false, THREAD);
3986     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3987   }
3988 
3989   // Leave arrays of jmethodIDs and itable index cache unchanged
3990 
3991   // Copy the "source file name" attribute from new class version
3992   the_class->set_source_file_name_index(
3993     scratch_class->source_file_name_index());
3994 
3995   // Copy the "source debug extension" attribute from new class version
3996   the_class->set_source_debug_extension(
3997     scratch_class->source_debug_extension(),
3998     scratch_class->source_debug_extension() == NULL ? 0 :
3999     (int)strlen(scratch_class->source_debug_extension()));
4000 
4001   // Use of javac -g could be different in the old and the new
4002   if (scratch_class->access_flags().has_localvariable_table() !=
4003       the_class->access_flags().has_localvariable_table()) {
4004 
4005     AccessFlags flags = the_class->access_flags();
4006     if (scratch_class->access_flags().has_localvariable_table()) {
4007       flags.set_has_localvariable_table();
4008     } else {
4009       flags.clear_has_localvariable_table();
4010     }
4011     the_class->set_access_flags(flags);
4012   }
4013 
4014   swap_annotations(the_class, scratch_class);
4015 
4016   // Replace minor version number of class file
4017   u2 old_minor_version = the_class->minor_version();
4018   the_class->set_minor_version(scratch_class->minor_version());
4019   scratch_class->set_minor_version(old_minor_version);
4020 
4021   // Replace major version number of class file
4022   u2 old_major_version = the_class->major_version();
4023   the_class->set_major_version(scratch_class->major_version());
4024   scratch_class->set_major_version(old_major_version);
4025 
4026   // Replace CP indexes for class and name+type of enclosing method
4027   u2 old_class_idx  = the_class->enclosing_method_class_index();
4028   u2 old_method_idx = the_class->enclosing_method_method_index();
4029   the_class->set_enclosing_method_indices(
4030     scratch_class->enclosing_method_class_index(),
4031     scratch_class->enclosing_method_method_index());
4032   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4033 
4034   // Replace fingerprint data
4035   the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4036   the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4037 
4038   the_class->set_has_been_redefined();
4039 
4040   if (!the_class->should_be_initialized()) {
4041     // Class was already initialized, so AOT has only seen the original version.
4042     // We need to let AOT look at it again.
4043     AOTLoader::load_for_klass(the_class, THREAD);
4044   }
4045 
4046   // keep track of previous versions of this class
4047   the_class->add_previous_version(scratch_class, emcp_method_count);
4048 
4049   _timer_rsc_phase1.stop();
4050   if (log_is_enabled(Info, redefine, class, timer)) {
4051     _timer_rsc_phase2.start();
4052   }
4053 
4054   // Adjust constantpool caches and vtables for all classes
4055   // that reference methods of the evolved class.
4056   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4057   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4058 
4059   if (the_class->oop_map_cache() != NULL) {
4060     // Flush references to any obsolete methods from the oop map cache
4061     // so that obsolete methods are not pinned.
4062     the_class->oop_map_cache()->flush_obsolete_entries();
4063   }
4064 
4065   increment_class_counter((InstanceKlass *)the_class, THREAD);
4066   {
4067     ResourceMark rm(THREAD);
4068     // increment the classRedefinedCount field in the_class and in any
4069     // direct and indirect subclasses of the_class
4070     log_info(redefine, class, load)
4071       ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4072        the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4073     Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4074                              the_class->external_name(),
4075                              java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4076 
4077   }
4078   _timer_rsc_phase2.stop();
4079 } // end redefine_single_class()
4080 
4081 
4082 // Increment the classRedefinedCount field in the specific InstanceKlass
4083 // and in all direct and indirect subclasses.
4084 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4085   oop class_mirror = ik->java_mirror();
4086   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4087   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4088   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4089 
4090   if (class_oop != _the_class) {
4091     // _the_class count is printed at end of redefine_single_class()
4092     log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4093   }
4094 
4095   for (Klass *subk = ik->subklass(); subk != NULL;
4096        subk = subk->next_sibling()) {
4097     if (subk->is_instance_klass()) {
4098       // Only update instanceKlasses
4099       InstanceKlass *subik = InstanceKlass::cast(subk);
4100       // recursively do subclasses of the current subclass
4101       increment_class_counter(subik, THREAD);
4102     }
4103   }
4104 }
4105 
4106 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4107   bool no_old_methods = true;  // be optimistic
4108 
4109   // Both array and instance classes have vtables.
4110   // a vtable should never contain old or obsolete methods
4111   ResourceMark rm(_thread);
4112   if (k->vtable_length() > 0 &&
4113       !k->vtable().check_no_old_or_obsolete_entries()) {
4114     if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4115       log_trace(redefine, class, obsolete, metadata)
4116         ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4117          k->signature_name());
4118       k->vtable().dump_vtable();
4119     }
4120     no_old_methods = false;
4121   }
4122 
4123   if (k->is_instance_klass()) {
4124     HandleMark hm(_thread);
4125     InstanceKlass *ik = InstanceKlass::cast(k);
4126 
4127     // an itable should never contain old or obsolete methods
4128     if (ik->itable_length() > 0 &&
4129         !ik->itable().check_no_old_or_obsolete_entries()) {
4130       if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4131         log_trace(redefine, class, obsolete, metadata)
4132           ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4133            ik->signature_name());
4134         ik->itable().dump_itable();
4135       }
4136       no_old_methods = false;
4137     }
4138 
4139     // the constant pool cache should never contain non-deleted old or obsolete methods
4140     if (ik->constants() != NULL &&
4141         ik->constants()->cache() != NULL &&
4142         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4143       if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4144         log_trace(redefine, class, obsolete, metadata)
4145           ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4146            ik->signature_name());
4147         ik->constants()->cache()->dump_cache();
4148       }
4149       no_old_methods = false;
4150     }
4151   }
4152 
4153   // print and fail guarantee if old methods are found.
4154   if (!no_old_methods) {
4155     if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4156       dump_methods();
4157     } else {
4158       log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4159         "to see more info about the following guarantee() failure.");
4160     }
4161     guarantee(false, "OLD and/or OBSOLETE method(s) found");
4162   }
4163 }
4164 
4165 
4166 void VM_RedefineClasses::dump_methods() {
4167   int j;
4168   log_trace(redefine, class, dump)("_old_methods --");
4169   for (j = 0; j < _old_methods->length(); ++j) {
4170     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4171     Method* m = _old_methods->at(j);
4172     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4173     m->access_flags().print_on(&log_stream);
4174     log_stream.print(" --  ");
4175     m->print_name(&log_stream);
4176     log_stream.cr();
4177   }
4178   log_trace(redefine, class, dump)("_new_methods --");
4179   for (j = 0; j < _new_methods->length(); ++j) {
4180     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4181     Method* m = _new_methods->at(j);
4182     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4183     m->access_flags().print_on(&log_stream);
4184     log_stream.print(" --  ");
4185     m->print_name(&log_stream);
4186     log_stream.cr();
4187   }
4188   log_trace(redefine, class, dump)("_matching_methods --");
4189   for (j = 0; j < _matching_methods_length; ++j) {
4190     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4191     Method* m = _matching_old_methods[j];
4192     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4193     m->access_flags().print_on(&log_stream);
4194     log_stream.print(" --  ");
4195     m->print_name();
4196     log_stream.cr();
4197 
4198     m = _matching_new_methods[j];
4199     log_stream.print("      (%5d)  ", m->vtable_index());
4200     m->access_flags().print_on(&log_stream);
4201     log_stream.cr();
4202   }
4203   log_trace(redefine, class, dump)("_deleted_methods --");
4204   for (j = 0; j < _deleted_methods_length; ++j) {
4205     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4206     Method* m = _deleted_methods[j];
4207     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4208     m->access_flags().print_on(&log_stream);
4209     log_stream.print(" --  ");
4210     m->print_name(&log_stream);
4211     log_stream.cr();
4212   }
4213   log_trace(redefine, class, dump)("_added_methods --");
4214   for (j = 0; j < _added_methods_length; ++j) {
4215     LogStreamHandle(Trace, redefine, class, dump) log_stream;
4216     Method* m = _added_methods[j];
4217     log_stream.print("%4d  (%5d)  ", j, m->vtable_index());
4218     m->access_flags().print_on(&log_stream);
4219     log_stream.print(" --  ");
4220     m->print_name(&log_stream);
4221     log_stream.cr();
4222   }
4223 }
4224 
4225 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4226   VM_Operation::print_on_error(st);
4227   if (_the_class != NULL) {
4228     ResourceMark rm;
4229     st->print_cr(", redefining class %s", _the_class->external_name());
4230   }
4231 }