1 /*
   2  * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"
  27 #include "classfile/verifier.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "interpreter/oopMapCache.hpp"
  30 #include "interpreter/rewriter.hpp"
  31 #include "memory/gcLocker.hpp"
  32 #include "memory/universe.inline.hpp"
  33 #include "oops/fieldStreams.hpp"
  34 #include "oops/klassVtable.hpp"
  35 #include "prims/jvmtiImpl.hpp"
  36 #include "prims/jvmtiRedefineClasses.hpp"
  37 #include "prims/methodComparator.hpp"
  38 #include "runtime/deoptimization.hpp"
  39 #include "runtime/relocator.hpp"
  40 #include "utilities/bitMap.inline.hpp"
  41 
  42 
  43 objArrayOop VM_RedefineClasses::_old_methods = NULL;
  44 objArrayOop VM_RedefineClasses::_new_methods = NULL;
  45 methodOop*  VM_RedefineClasses::_matching_old_methods = NULL;
  46 methodOop*  VM_RedefineClasses::_matching_new_methods = NULL;
  47 methodOop*  VM_RedefineClasses::_deleted_methods      = NULL;
  48 methodOop*  VM_RedefineClasses::_added_methods        = NULL;
  49 int         VM_RedefineClasses::_matching_methods_length = 0;
  50 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  51 int         VM_RedefineClasses::_added_methods_length    = 0;
  52 klassOop    VM_RedefineClasses::_the_class_oop = NULL;
  53 
  54 
  55 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  56                                        const jvmtiClassDefinition *class_defs,
  57                                        JvmtiClassLoadKind class_load_kind) {
  58   _class_count = class_count;
  59   _class_defs = class_defs;
  60   _class_load_kind = class_load_kind;
  61   _res = JVMTI_ERROR_NONE;
  62 }
  63 
  64 bool VM_RedefineClasses::doit_prologue() {
  65   if (_class_count == 0) {
  66     _res = JVMTI_ERROR_NONE;
  67     return false;
  68   }
  69   if (_class_defs == NULL) {
  70     _res = JVMTI_ERROR_NULL_POINTER;
  71     return false;
  72   }
  73   for (int i = 0; i < _class_count; i++) {
  74     if (_class_defs[i].klass == NULL) {
  75       _res = JVMTI_ERROR_INVALID_CLASS;
  76       return false;
  77     }
  78     if (_class_defs[i].class_byte_count == 0) {
  79       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
  80       return false;
  81     }
  82     if (_class_defs[i].class_bytes == NULL) {
  83       _res = JVMTI_ERROR_NULL_POINTER;
  84       return false;
  85     }
  86   }
  87 
  88   // Start timer after all the sanity checks; not quite accurate, but
  89   // better than adding a bunch of stop() calls.
  90   RC_TIMER_START(_timer_vm_op_prologue);
  91 
  92   // We first load new class versions in the prologue, because somewhere down the
  93   // call chain it is required that the current thread is a Java thread.
  94   _res = load_new_class_versions(Thread::current());
  95   if (_res != JVMTI_ERROR_NONE) {
  96     // Free os::malloc allocated memory in load_new_class_version.
  97     os::free(_scratch_classes);
  98     RC_TIMER_STOP(_timer_vm_op_prologue);
  99     return false;
 100   }
 101 
 102   RC_TIMER_STOP(_timer_vm_op_prologue);
 103   return true;
 104 }
 105 
 106 void VM_RedefineClasses::doit() {
 107   Thread *thread = Thread::current();
 108 
 109   if (UseSharedSpaces) {
 110     // Sharing is enabled so we remap the shared readonly space to
 111     // shared readwrite, private just in case we need to redefine
 112     // a shared class. We do the remap during the doit() phase of
 113     // the safepoint to be safer.
 114     if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {
 115       RC_TRACE_WITH_THREAD(0x00000001, thread,
 116         ("failed to remap shared readonly space to readwrite, private"));
 117       _res = JVMTI_ERROR_INTERNAL;
 118       return;
 119     }
 120   }
 121 
 122   for (int i = 0; i < _class_count; i++) {
 123     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 124   }
 125   // Disable any dependent concurrent compilations
 126   SystemDictionary::notice_modification();
 127 
 128   // Set flag indicating that some invariants are no longer true.
 129   // See jvmtiExport.hpp for detailed explanation.
 130   JvmtiExport::set_has_redefined_a_class();
 131 
 132 #ifdef ASSERT





 133   SystemDictionary::classes_do(check_class, thread);


 134 #endif
 135 }
 136 
 137 void VM_RedefineClasses::doit_epilogue() {
 138   // Free os::malloc allocated memory.
 139   // The memory allocated in redefine will be free'ed in next VM operation.
 140   os::free(_scratch_classes);
 141 
 142   if (RC_TRACE_ENABLED(0x00000004)) {
 143     // Used to have separate timers for "doit" and "all", but the timer
 144     // overhead skewed the measurements.
 145     jlong doit_time = _timer_rsc_phase1.milliseconds() +
 146                       _timer_rsc_phase2.milliseconds();
 147     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 148 
 149     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
 150       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
 151       _timer_vm_op_prologue.milliseconds(), doit_time));
 152     RC_TRACE(0x00000004,
 153       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
 154        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
 155   }
 156 }
 157 
 158 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 159   // classes for primitives cannot be redefined
 160   if (java_lang_Class::is_primitive(klass_mirror)) {
 161     return false;
 162   }
 163   klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
 164   // classes for arrays cannot be redefined
 165   if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
 166     return false;
 167   }
 168   return true;
 169 }
 170 
 171 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 172 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 173 // direct CP entries, there is just the current entry to append. For
 174 // indirect and double-indirect CP entries, there are zero or more
 175 // referenced CP entries along with the current entry to append.
 176 // Indirect and double-indirect CP entries are handled by recursive
 177 // calls to append_entry() as needed. The referenced CP entries are
 178 // always appended to *merge_cp_p before the referee CP entry. These
 179 // referenced CP entries may already exist in *merge_cp_p in which case
 180 // there is nothing extra to append and only the current entry is
 181 // appended.
 182 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
 183        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 184        TRAPS) {
 185 
 186   // append is different depending on entry tag type
 187   switch (scratch_cp->tag_at(scratch_i).value()) {
 188 
 189     // The old verifier is implemented outside the VM. It loads classes,
 190     // but does not resolve constant pool entries directly so we never
 191     // see Class entries here with the old verifier. Similarly the old
 192     // verifier does not like Class entries in the input constant pool.
 193     // The split-verifier is implemented in the VM so it can optionally
 194     // and directly resolve constant pool entries to load classes. The
 195     // split-verifier can accept either Class entries or UnresolvedClass
 196     // entries in the input constant pool. We revert the appended copy
 197     // back to UnresolvedClass so that either verifier will be happy
 198     // with the constant pool entry.
 199     case JVM_CONSTANT_Class:
 200     {
 201       // revert the copy to JVM_CONSTANT_UnresolvedClass
 202       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
 203         scratch_cp->klass_name_at(scratch_i));
 204 
 205       if (scratch_i != *merge_cp_length_p) {
 206         // The new entry in *merge_cp_p is at a different index than
 207         // the new entry in scratch_cp so we need to map the index values.
 208         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 209       }
 210       (*merge_cp_length_p)++;
 211     } break;
 212 
 213     // these are direct CP entries so they can be directly appended,
 214     // but double and long take two constant pool entries
 215     case JVM_CONSTANT_Double:  // fall through
 216     case JVM_CONSTANT_Long:
 217     {
 218       constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 219         THREAD);
 220 
 221       if (scratch_i != *merge_cp_length_p) {
 222         // The new entry in *merge_cp_p is at a different index than
 223         // the new entry in scratch_cp so we need to map the index values.
 224         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 225       }
 226       (*merge_cp_length_p) += 2;
 227     } break;
 228 
 229     // these are direct CP entries so they can be directly appended
 230     case JVM_CONSTANT_Float:   // fall through
 231     case JVM_CONSTANT_Integer: // fall through
 232     case JVM_CONSTANT_Utf8:    // fall through
 233 
 234     // This was an indirect CP entry, but it has been changed into
 235     // an interned string so this entry can be directly appended.
 236     case JVM_CONSTANT_String:      // fall through
 237 
 238     // These were indirect CP entries, but they have been changed into
 239     // Symbol*s so these entries can be directly appended.
 240     case JVM_CONSTANT_UnresolvedClass:  // fall through
 241     case JVM_CONSTANT_UnresolvedString:
 242     {
 243       constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 244         THREAD);
 245 
 246       if (scratch_i != *merge_cp_length_p) {
 247         // The new entry in *merge_cp_p is at a different index than
 248         // the new entry in scratch_cp so we need to map the index values.
 249         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 250       }
 251       (*merge_cp_length_p)++;
 252     } break;
 253 
 254     // this is an indirect CP entry so it needs special handling
 255     case JVM_CONSTANT_NameAndType:
 256     {
 257       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 258       int new_name_ref_i = 0;
 259       bool match = (name_ref_i < *merge_cp_length_p) &&
 260         scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
 261           THREAD);
 262       if (!match) {
 263         // forward reference in *merge_cp_p or not a direct match
 264 
 265         int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
 266           THREAD);
 267         if (found_i != 0) {
 268           guarantee(found_i != name_ref_i,
 269             "compare_entry_to() and find_matching_entry() do not agree");
 270 
 271           // Found a matching entry somewhere else in *merge_cp_p so
 272           // just need a mapping entry.
 273           new_name_ref_i = found_i;
 274           map_index(scratch_cp, name_ref_i, found_i);
 275         } else {
 276           // no match found so we have to append this entry to *merge_cp_p
 277           append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
 278             THREAD);
 279           // The above call to append_entry() can only append one entry
 280           // so the post call query of *merge_cp_length_p is only for
 281           // the sake of consistency.
 282           new_name_ref_i = *merge_cp_length_p - 1;
 283         }
 284       }
 285 
 286       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 287       int new_signature_ref_i = 0;
 288       match = (signature_ref_i < *merge_cp_length_p) &&
 289         scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
 290           signature_ref_i, THREAD);
 291       if (!match) {
 292         // forward reference in *merge_cp_p or not a direct match
 293 
 294         int found_i = scratch_cp->find_matching_entry(signature_ref_i,
 295           *merge_cp_p, THREAD);
 296         if (found_i != 0) {
 297           guarantee(found_i != signature_ref_i,
 298             "compare_entry_to() and find_matching_entry() do not agree");
 299 
 300           // Found a matching entry somewhere else in *merge_cp_p so
 301           // just need a mapping entry.
 302           new_signature_ref_i = found_i;
 303           map_index(scratch_cp, signature_ref_i, found_i);
 304         } else {
 305           // no match found so we have to append this entry to *merge_cp_p
 306           append_entry(scratch_cp, signature_ref_i, merge_cp_p,
 307             merge_cp_length_p, THREAD);
 308           // The above call to append_entry() can only append one entry
 309           // so the post call query of *merge_cp_length_p is only for
 310           // the sake of consistency.
 311           new_signature_ref_i = *merge_cp_length_p - 1;
 312         }
 313       }
 314 
 315       // If the referenced entries already exist in *merge_cp_p, then
 316       // both new_name_ref_i and new_signature_ref_i will both be 0.
 317       // In that case, all we are appending is the current entry.
 318       if (new_name_ref_i == 0) {
 319         new_name_ref_i = name_ref_i;
 320       } else {
 321         RC_TRACE(0x00080000,
 322           ("NameAndType entry@%d name_ref_index change: %d to %d",
 323           *merge_cp_length_p, name_ref_i, new_name_ref_i));
 324       }
 325       if (new_signature_ref_i == 0) {
 326         new_signature_ref_i = signature_ref_i;
 327       } else {
 328         RC_TRACE(0x00080000,
 329           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 330           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
 331       }
 332 
 333       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 334         new_name_ref_i, new_signature_ref_i);
 335       if (scratch_i != *merge_cp_length_p) {
 336         // The new entry in *merge_cp_p is at a different index than
 337         // the new entry in scratch_cp so we need to map the index values.
 338         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 339       }
 340       (*merge_cp_length_p)++;
 341     } break;
 342 
 343     // this is a double-indirect CP entry so it needs special handling
 344     case JVM_CONSTANT_Fieldref:           // fall through
 345     case JVM_CONSTANT_InterfaceMethodref: // fall through
 346     case JVM_CONSTANT_Methodref:
 347     {
 348       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 349       int new_klass_ref_i = 0;
 350       bool match = (klass_ref_i < *merge_cp_length_p) &&
 351         scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
 352           THREAD);
 353       if (!match) {
 354         // forward reference in *merge_cp_p or not a direct match
 355 
 356         int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
 357           THREAD);
 358         if (found_i != 0) {
 359           guarantee(found_i != klass_ref_i,
 360             "compare_entry_to() and find_matching_entry() do not agree");
 361 
 362           // Found a matching entry somewhere else in *merge_cp_p so
 363           // just need a mapping entry.
 364           new_klass_ref_i = found_i;
 365           map_index(scratch_cp, klass_ref_i, found_i);
 366         } else {
 367           // no match found so we have to append this entry to *merge_cp_p
 368           append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
 369             THREAD);
 370           // The above call to append_entry() can only append one entry
 371           // so the post call query of *merge_cp_length_p is only for
 372           // the sake of consistency. Without the optimization where we
 373           // use JVM_CONSTANT_UnresolvedClass, then up to two entries
 374           // could be appended.
 375           new_klass_ref_i = *merge_cp_length_p - 1;
 376         }
 377       }
 378 
 379       int name_and_type_ref_i =
 380         scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 381       int new_name_and_type_ref_i = 0;
 382       match = (name_and_type_ref_i < *merge_cp_length_p) &&
 383         scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
 384           name_and_type_ref_i, THREAD);
 385       if (!match) {
 386         // forward reference in *merge_cp_p or not a direct match
 387 
 388         int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
 389           *merge_cp_p, THREAD);
 390         if (found_i != 0) {
 391           guarantee(found_i != name_and_type_ref_i,
 392             "compare_entry_to() and find_matching_entry() do not agree");
 393 
 394           // Found a matching entry somewhere else in *merge_cp_p so
 395           // just need a mapping entry.
 396           new_name_and_type_ref_i = found_i;
 397           map_index(scratch_cp, name_and_type_ref_i, found_i);
 398         } else {
 399           // no match found so we have to append this entry to *merge_cp_p
 400           append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
 401             merge_cp_length_p, THREAD);
 402           // The above call to append_entry() can append more than
 403           // one entry so the post call query of *merge_cp_length_p
 404           // is required in order to get the right index for the
 405           // JVM_CONSTANT_NameAndType entry.
 406           new_name_and_type_ref_i = *merge_cp_length_p - 1;
 407         }
 408       }
 409 
 410       // If the referenced entries already exist in *merge_cp_p, then
 411       // both new_klass_ref_i and new_name_and_type_ref_i will both be
 412       // 0. In that case, all we are appending is the current entry.
 413       if (new_klass_ref_i == 0) {
 414         new_klass_ref_i = klass_ref_i;
 415       }
 416       if (new_name_and_type_ref_i == 0) {
 417         new_name_and_type_ref_i = name_and_type_ref_i;
 418       }
 419 
 420       const char *entry_name;
 421       switch (scratch_cp->tag_at(scratch_i).value()) {
 422       case JVM_CONSTANT_Fieldref:
 423         entry_name = "Fieldref";
 424         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 425           new_name_and_type_ref_i);
 426         break;
 427       case JVM_CONSTANT_InterfaceMethodref:
 428         entry_name = "IFMethodref";
 429         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 430           new_klass_ref_i, new_name_and_type_ref_i);
 431         break;
 432       case JVM_CONSTANT_Methodref:
 433         entry_name = "Methodref";
 434         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 435           new_name_and_type_ref_i);
 436         break;
 437       default:
 438         guarantee(false, "bad switch");
 439         break;
 440       }
 441 
 442       if (klass_ref_i != new_klass_ref_i) {
 443         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
 444           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
 445       }
 446       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 447         RC_TRACE(0x00080000,
 448           ("%s entry@%d name_and_type_index changed: %d to %d",
 449           entry_name, *merge_cp_length_p, name_and_type_ref_i,
 450           new_name_and_type_ref_i));
 451       }
 452 
 453       if (scratch_i != *merge_cp_length_p) {
 454         // The new entry in *merge_cp_p is at a different index than
 455         // the new entry in scratch_cp so we need to map the index values.
 456         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 457       }
 458       (*merge_cp_length_p)++;
 459     } break;
 460 
 461     // At this stage, Class or UnresolvedClass could be here, but not
 462     // ClassIndex
 463     case JVM_CONSTANT_ClassIndex: // fall through
 464 
 465     // Invalid is used as the tag for the second constant pool entry
 466     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 467     // not be seen by itself.
 468     case JVM_CONSTANT_Invalid: // fall through
 469 
 470     // At this stage, String or UnresolvedString could be here, but not
 471     // StringIndex
 472     case JVM_CONSTANT_StringIndex: // fall through
 473 
 474     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 475     // here
 476     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 477 
 478     default:
 479     {
 480       // leave a breadcrumb
 481       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 482       ShouldNotReachHere();
 483     } break;
 484   } // end switch tag value
 485 } // end append_entry()
 486 
 487 
 488 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {
 489   typeArrayOop save;
 490 
 491   save = scratch_class->get_method_annotations_of(i);
 492   scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));
 493   scratch_class->set_method_annotations_of(j, save);
 494 
 495   save = scratch_class->get_method_parameter_annotations_of(i);
 496   scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));
 497   scratch_class->set_method_parameter_annotations_of(j, save);
 498 
 499   save = scratch_class->get_method_default_annotations_of(i);
 500   scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));
 501   scratch_class->set_method_default_annotations_of(j, save);
 502 }
 503 
 504 
 505 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 506              instanceKlassHandle the_class,
 507              instanceKlassHandle scratch_class) {
 508   int i;
 509 
 510   // Check superclasses, or rather their names, since superclasses themselves can be
 511   // requested to replace.
 512   // Check for NULL superclass first since this might be java.lang.Object
 513   if (the_class->super() != scratch_class->super() &&
 514       (the_class->super() == NULL || scratch_class->super() == NULL ||
 515        Klass::cast(the_class->super())->name() !=
 516        Klass::cast(scratch_class->super())->name())) {
 517     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 518   }
 519 
 520   // Check if the number, names and order of directly implemented interfaces are the same.
 521   // I think in principle we should just check if the sets of names of directly implemented
 522   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 523   // .java file, also changes in .class file) should not matter. However, comparing sets is
 524   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 525   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 526   // rely on it somewhere.
 527   objArrayOop k_interfaces = the_class->local_interfaces();
 528   objArrayOop k_new_interfaces = scratch_class->local_interfaces();
 529   int n_intfs = k_interfaces->length();
 530   if (n_intfs != k_new_interfaces->length()) {
 531     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 532   }
 533   for (i = 0; i < n_intfs; i++) {
 534     if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=
 535         Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
 536       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 537     }
 538   }
 539 
 540   // Check whether class is in the error init state.
 541   if (the_class->is_in_error_state()) {
 542     // TBD #5057930: special error code is needed in 1.6
 543     return JVMTI_ERROR_INVALID_CLASS;
 544   }
 545 
 546   // Check whether class modifiers are the same.
 547   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 548   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 549   if (old_flags != new_flags) {
 550     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 551   }
 552 
 553   // Check if the number, names, types and order of fields declared in these classes
 554   // are the same.
 555   JavaFieldStream old_fs(the_class);
 556   JavaFieldStream new_fs(scratch_class);
 557   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 558     // access
 559     old_flags = old_fs.access_flags().as_short();
 560     new_flags = new_fs.access_flags().as_short();
 561     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 562       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 563     }
 564     // offset
 565     if (old_fs.offset() != new_fs.offset()) {
 566       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 567     }
 568     // name and signature
 569     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 570     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 571     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 572     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 573     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 574       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 575     }
 576   }
 577 
 578   // If both streams aren't done then we have a differing number of
 579   // fields.
 580   if (!old_fs.done() || !new_fs.done()) {
 581     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 582   }
 583 
 584   // Do a parallel walk through the old and new methods. Detect
 585   // cases where they match (exist in both), have been added in
 586   // the new methods, or have been deleted (exist only in the
 587   // old methods).  The class file parser places methods in order
 588   // by method name, but does not order overloaded methods by
 589   // signature.  In order to determine what fate befell the methods,
 590   // this code places the overloaded new methods that have matching
 591   // old methods in the same order as the old methods and places
 592   // new overloaded methods at the end of overloaded methods of
 593   // that name. The code for this order normalization is adapted
 594   // from the algorithm used in instanceKlass::find_method().
 595   // Since we are swapping out of order entries as we find them,
 596   // we only have to search forward through the overloaded methods.
 597   // Methods which are added and have the same name as an existing
 598   // method (but different signature) will be put at the end of
 599   // the methods with that name, and the name mismatch code will
 600   // handle them.
 601   objArrayHandle k_old_methods(the_class->methods());
 602   objArrayHandle k_new_methods(scratch_class->methods());
 603   int n_old_methods = k_old_methods->length();
 604   int n_new_methods = k_new_methods->length();
 605 
 606   int ni = 0;
 607   int oi = 0;
 608   while (true) {
 609     methodOop k_old_method;
 610     methodOop k_new_method;
 611     enum { matched, added, deleted, undetermined } method_was = undetermined;
 612 
 613     if (oi >= n_old_methods) {
 614       if (ni >= n_new_methods) {
 615         break; // we've looked at everything, done
 616       }
 617       // New method at the end
 618       k_new_method = (methodOop) k_new_methods->obj_at(ni);
 619       method_was = added;
 620     } else if (ni >= n_new_methods) {
 621       // Old method, at the end, is deleted
 622       k_old_method = (methodOop) k_old_methods->obj_at(oi);
 623       method_was = deleted;
 624     } else {
 625       // There are more methods in both the old and new lists
 626       k_old_method = (methodOop) k_old_methods->obj_at(oi);
 627       k_new_method = (methodOop) k_new_methods->obj_at(ni);
 628       if (k_old_method->name() != k_new_method->name()) {
 629         // Methods are sorted by method name, so a mismatch means added
 630         // or deleted
 631         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 632           method_was = added;
 633         } else {
 634           method_was = deleted;
 635         }
 636       } else if (k_old_method->signature() == k_new_method->signature()) {
 637         // Both the name and signature match
 638         method_was = matched;
 639       } else {
 640         // The name matches, but the signature doesn't, which means we have to
 641         // search forward through the new overloaded methods.
 642         int nj;  // outside the loop for post-loop check
 643         for (nj = ni + 1; nj < n_new_methods; nj++) {
 644           methodOop m = (methodOop)k_new_methods->obj_at(nj);
 645           if (k_old_method->name() != m->name()) {
 646             // reached another method name so no more overloaded methods
 647             method_was = deleted;
 648             break;
 649           }
 650           if (k_old_method->signature() == m->signature()) {
 651             // found a match so swap the methods
 652             k_new_methods->obj_at_put(ni, m);
 653             k_new_methods->obj_at_put(nj, k_new_method);
 654             k_new_method = m;
 655             method_was = matched;
 656             break;
 657           }
 658         }
 659 
 660         if (nj >= n_new_methods) {
 661           // reached the end without a match; so method was deleted
 662           method_was = deleted;
 663         }
 664       }
 665     }
 666 
 667     switch (method_was) {
 668     case matched:
 669       // methods match, be sure modifiers do too
 670       old_flags = (jushort) k_old_method->access_flags().get_flags();
 671       new_flags = (jushort) k_new_method->access_flags().get_flags();
 672       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 673         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 674       }
 675       {
 676         u2 new_num = k_new_method->method_idnum();
 677         u2 old_num = k_old_method->method_idnum();
 678         if (new_num != old_num) {
 679           methodOop idnum_owner = scratch_class->method_with_idnum(old_num);
 680           if (idnum_owner != NULL) {
 681             // There is already a method assigned this idnum -- switch them
 682             idnum_owner->set_method_idnum(new_num);
 683           }
 684           k_new_method->set_method_idnum(old_num);
 685           swap_all_method_annotations(old_num, new_num, scratch_class);
 686         }
 687       }
 688       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
 689                             k_new_method->name_and_sig_as_C_string(), ni,
 690                             k_old_method->name_and_sig_as_C_string(), oi));
 691       // advance to next pair of methods
 692       ++oi;
 693       ++ni;
 694       break;
 695     case added:
 696       // method added, see if it is OK
 697       new_flags = (jushort) k_new_method->access_flags().get_flags();
 698       if ((new_flags & JVM_ACC_PRIVATE) == 0
 699            // hack: private should be treated as final, but alas
 700           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 701          ) {
 702         // new methods must be private
 703         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 704       }
 705       {
 706         u2 num = the_class->next_method_idnum();
 707         if (num == constMethodOopDesc::UNSET_IDNUM) {
 708           // cannot add any more methods
 709           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 710         }
 711         u2 new_num = k_new_method->method_idnum();
 712         methodOop idnum_owner = scratch_class->method_with_idnum(num);
 713         if (idnum_owner != NULL) {
 714           // There is already a method assigned this idnum -- switch them
 715           idnum_owner->set_method_idnum(new_num);
 716         }
 717         k_new_method->set_method_idnum(num);
 718         swap_all_method_annotations(new_num, num, scratch_class);
 719       }
 720       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
 721                             k_new_method->name_and_sig_as_C_string(), ni));
 722       ++ni; // advance to next new method
 723       break;
 724     case deleted:
 725       // method deleted, see if it is OK
 726       old_flags = (jushort) k_old_method->access_flags().get_flags();
 727       if ((old_flags & JVM_ACC_PRIVATE) == 0
 728            // hack: private should be treated as final, but alas
 729           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 730          ) {
 731         // deleted methods must be private
 732         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 733       }
 734       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
 735                             k_old_method->name_and_sig_as_C_string(), oi));
 736       ++oi; // advance to next old method
 737       break;
 738     default:
 739       ShouldNotReachHere();
 740     }
 741   }
 742 
 743   return JVMTI_ERROR_NONE;
 744 }
 745 
 746 
 747 // Find new constant pool index value for old constant pool index value
 748 // by seaching the index map. Returns zero (0) if there is no mapped
 749 // value for the old constant pool index.
 750 int VM_RedefineClasses::find_new_index(int old_index) {
 751   if (_index_map_count == 0) {
 752     // map is empty so nothing can be found
 753     return 0;
 754   }
 755 
 756   if (old_index < 1 || old_index >= _index_map_p->length()) {
 757     // The old_index is out of range so it is not mapped. This should
 758     // not happen in regular constant pool merging use, but it can
 759     // happen if a corrupt annotation is processed.
 760     return 0;
 761   }
 762 
 763   int value = _index_map_p->at(old_index);
 764   if (value == -1) {
 765     // the old_index is not mapped
 766     return 0;
 767   }
 768 
 769   return value;
 770 } // end find_new_index()
 771 
 772 
 773 // Returns true if the current mismatch is due to a resolved/unresolved
 774 // class pair. Otherwise, returns false.
 775 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
 776        int index1, constantPoolHandle cp2, int index2) {
 777 
 778   jbyte t1 = cp1->tag_at(index1).value();
 779   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 780     return false;  // wrong entry type; not our special case
 781   }
 782 
 783   jbyte t2 = cp2->tag_at(index2).value();
 784   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 785     return false;  // wrong entry type; not our special case
 786   }
 787 
 788   if (t1 == t2) {
 789     return false;  // not a mismatch; not our special case
 790   }
 791 
 792   char *s1 = cp1->klass_name_at(index1)->as_C_string();
 793   char *s2 = cp2->klass_name_at(index2)->as_C_string();
 794   if (strcmp(s1, s2) != 0) {
 795     return false;  // strings don't match; not our special case
 796   }
 797 
 798   return true;  // made it through the gauntlet; this is our special case
 799 } // end is_unresolved_class_mismatch()
 800 
 801 
 802 // Returns true if the current mismatch is due to a resolved/unresolved
 803 // string pair. Otherwise, returns false.
 804 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,
 805        int index1, constantPoolHandle cp2, int index2) {
 806 
 807   jbyte t1 = cp1->tag_at(index1).value();
 808   if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {
 809     return false;  // wrong entry type; not our special case
 810   }
 811 
 812   jbyte t2 = cp2->tag_at(index2).value();
 813   if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {
 814     return false;  // wrong entry type; not our special case
 815   }
 816 
 817   if (t1 == t2) {
 818     return false;  // not a mismatch; not our special case
 819   }
 820 
 821   char *s1 = cp1->string_at_noresolve(index1);
 822   char *s2 = cp2->string_at_noresolve(index2);
 823   if (strcmp(s1, s2) != 0) {
 824     return false;  // strings don't match; not our special case
 825   }
 826 
 827   return true;  // made it through the gauntlet; this is our special case
 828 } // end is_unresolved_string_mismatch()
 829 
 830 
 831 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
 832   // For consistency allocate memory using os::malloc wrapper.
 833   _scratch_classes = (instanceKlassHandle *)
 834     os::malloc(sizeof(instanceKlassHandle) * _class_count);
 835   if (_scratch_classes == NULL) {
 836     return JVMTI_ERROR_OUT_OF_MEMORY;
 837   }
 838 
 839   ResourceMark rm(THREAD);
 840 
 841   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
 842   // state can only be NULL if the current thread is exiting which
 843   // should not happen since we're trying to do a RedefineClasses
 844   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
 845   for (int i = 0; i < _class_count; i++) {
 846     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 847     // classes for primitives cannot be redefined
 848     if (!is_modifiable_class(mirror)) {
 849       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
 850     }
 851     klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
 852     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
 853     Symbol*  the_class_sym = the_class->name();
 854 
 855     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 856     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
 857       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
 858       the_class->external_name(), _class_load_kind,
 859       os::available_memory() >> 10));
 860 
 861     ClassFileStream st((u1*) _class_defs[i].class_bytes,
 862       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
 863 
 864     // Parse the stream.
 865     Handle the_class_loader(THREAD, the_class->class_loader());
 866     Handle protection_domain(THREAD, the_class->protection_domain());
 867     // Set redefined class handle in JvmtiThreadState class.
 868     // This redefined class is sent to agent event handler for class file
 869     // load hook event.
 870     state->set_class_being_redefined(&the_class, _class_load_kind);
 871 
 872     klassOop k = SystemDictionary::parse_stream(the_class_sym,
 873                                                 the_class_loader,
 874                                                 protection_domain,
 875                                                 &st,
 876                                                 THREAD);
 877     // Clear class_being_redefined just to be sure.
 878     state->clear_class_being_redefined();
 879 
 880     // TODO: if this is retransform, and nothing changed we can skip it
 881 
 882     instanceKlassHandle scratch_class (THREAD, k);
 883 
 884     if (HAS_PENDING_EXCEPTION) {
 885       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 886       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 887       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
 888         ex_name->as_C_string()));
 889       CLEAR_PENDING_EXCEPTION;
 890 
 891       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
 892         return JVMTI_ERROR_UNSUPPORTED_VERSION;
 893       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
 894         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
 895       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
 896         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
 897       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
 898         // The message will be "XXX (wrong name: YYY)"
 899         return JVMTI_ERROR_NAMES_DONT_MATCH;
 900       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 901         return JVMTI_ERROR_OUT_OF_MEMORY;
 902       } else {  // Just in case more exceptions can be thrown..
 903         return JVMTI_ERROR_FAILS_VERIFICATION;
 904       }
 905     }
 906 
 907     // Ensure class is linked before redefine
 908     if (!the_class->is_linked()) {
 909       the_class->link_class(THREAD);
 910       if (HAS_PENDING_EXCEPTION) {
 911         Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 912         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 913         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
 914           ex_name->as_C_string()));
 915         CLEAR_PENDING_EXCEPTION;
 916         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 917           return JVMTI_ERROR_OUT_OF_MEMORY;
 918         } else {
 919           return JVMTI_ERROR_INTERNAL;
 920         }
 921       }
 922     }
 923 
 924     // Do the validity checks in compare_and_normalize_class_versions()
 925     // before verifying the byte codes. By doing these checks first, we
 926     // limit the number of functions that require redirection from
 927     // the_class to scratch_class. In particular, we don't have to
 928     // modify JNI GetSuperclass() and thus won't change its performance.
 929     jvmtiError res = compare_and_normalize_class_versions(the_class,
 930                        scratch_class);
 931     if (res != JVMTI_ERROR_NONE) {
 932       return res;
 933     }
 934 
 935     // verify what the caller passed us
 936     {
 937       // The bug 6214132 caused the verification to fail.
 938       // Information about the_class and scratch_class is temporarily
 939       // recorded into jvmtiThreadState. This data is used to redirect
 940       // the_class to scratch_class in the JVM_* functions called by the
 941       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
 942       // description.
 943       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
 944       Verifier::verify(
 945         scratch_class, Verifier::ThrowException, true, THREAD);
 946     }
 947 
 948     if (HAS_PENDING_EXCEPTION) {
 949       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 950       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 951       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
 952         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
 953       CLEAR_PENDING_EXCEPTION;
 954       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 955         return JVMTI_ERROR_OUT_OF_MEMORY;
 956       } else {
 957         // tell the caller the bytecodes are bad
 958         return JVMTI_ERROR_FAILS_VERIFICATION;
 959       }
 960     }
 961 
 962     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
 963     if (res != JVMTI_ERROR_NONE) {
 964       return res;
 965     }
 966 
 967     if (VerifyMergedCPBytecodes) {
 968       // verify what we have done during constant pool merging
 969       {
 970         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
 971         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
 972       }
 973 
 974       if (HAS_PENDING_EXCEPTION) {
 975         Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 976         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 977         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
 978           ("verify_byte_codes post merge-CP exception: '%s'",
 979           ex_name->as_C_string()));
 980         CLEAR_PENDING_EXCEPTION;
 981         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 982           return JVMTI_ERROR_OUT_OF_MEMORY;
 983         } else {
 984           // tell the caller that constant pool merging screwed up
 985           return JVMTI_ERROR_INTERNAL;
 986         }
 987       }
 988     }
 989 
 990     Rewriter::rewrite(scratch_class, THREAD);
 991     if (!HAS_PENDING_EXCEPTION) {
 992       Rewriter::relocate_and_link(scratch_class, THREAD);
 993     }
 994     if (HAS_PENDING_EXCEPTION) {
 995       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 996       CLEAR_PENDING_EXCEPTION;
 997       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 998         return JVMTI_ERROR_OUT_OF_MEMORY;
 999       } else {
1000         return JVMTI_ERROR_INTERNAL;
1001       }
1002     }
1003 
1004     _scratch_classes[i] = scratch_class;
1005 
1006     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1007     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1008       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1009       the_class->external_name(), os::available_memory() >> 10));
1010   }
1011 
1012   return JVMTI_ERROR_NONE;
1013 }
1014 
1015 
1016 // Map old_index to new_index as needed. scratch_cp is only needed
1017 // for RC_TRACE() calls.
1018 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1019        int old_index, int new_index) {
1020   if (find_new_index(old_index) != 0) {
1021     // old_index is already mapped
1022     return;
1023   }
1024 
1025   if (old_index == new_index) {
1026     // no mapping is needed
1027     return;
1028   }
1029 
1030   _index_map_p->at_put(old_index, new_index);
1031   _index_map_count++;
1032 
1033   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1034     scratch_cp->tag_at(old_index).value(), old_index, new_index));
1035 } // end map_index()
1036 
1037 
1038 // Merge old_cp and scratch_cp and return the results of the merge via
1039 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1040 // merge_cp_length_p. The entries in old_cp occupy the same locations
1041 // in *merge_cp_p. Also creates a map of indices from entries in
1042 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1043 // entries are only created for entries in scratch_cp that occupy a
1044 // different location in *merged_cp_p.
1045 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1046        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1047        int *merge_cp_length_p, TRAPS) {
1048 
1049   if (merge_cp_p == NULL) {
1050     assert(false, "caller must provide scatch constantPool");
1051     return false; // robustness
1052   }
1053   if (merge_cp_length_p == NULL) {
1054     assert(false, "caller must provide scatch CP length");
1055     return false; // robustness
1056   }
1057   // Worst case we need old_cp->length() + scratch_cp()->length(),
1058   // but the caller might be smart so make sure we have at least
1059   // the minimum.
1060   if ((*merge_cp_p)->length() < old_cp->length()) {
1061     assert(false, "merge area too small");
1062     return false; // robustness
1063   }
1064 
1065   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1066     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1067     scratch_cp->length()));
1068 
1069   {
1070     // Pass 0:
1071     // The old_cp is copied to *merge_cp_p; this means that any code
1072     // using old_cp does not have to change. This work looks like a
1073     // perfect fit for constantPoolOop::copy_cp_to(), but we need to
1074     // handle one special case:
1075     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1076     // This will make verification happy.
1077 
1078     int old_i;  // index into old_cp
1079 
1080     // index zero (0) is not used in constantPools
1081     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1082       // leave debugging crumb
1083       jbyte old_tag = old_cp->tag_at(old_i).value();
1084       switch (old_tag) {
1085       case JVM_CONSTANT_Class:
1086       case JVM_CONSTANT_UnresolvedClass:
1087         // revert the copy to JVM_CONSTANT_UnresolvedClass
1088         // May be resolving while calling this so do the same for
1089         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1090         (*merge_cp_p)->unresolved_klass_at_put(old_i,
1091           old_cp->klass_name_at(old_i));
1092         break;
1093 
1094       case JVM_CONSTANT_Double:
1095       case JVM_CONSTANT_Long:
1096         // just copy the entry to *merge_cp_p, but double and long take
1097         // two constant pool entries
1098         constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1099         old_i++;
1100         break;
1101 
1102       default:
1103         // just copy the entry to *merge_cp_p
1104         constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1105         break;
1106       }
1107     } // end for each old_cp entry
1108 
1109     // We don't need to sanity check that *merge_cp_length_p is within
1110     // *merge_cp_p bounds since we have the minimum on-entry check above.
1111     (*merge_cp_length_p) = old_i;
1112   }
1113 
1114   // merge_cp_len should be the same as old_cp->length() at this point
1115   // so this trace message is really a "warm-and-breathing" message.
1116   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1117     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1118 
1119   int scratch_i;  // index into scratch_cp
1120   {
1121     // Pass 1a:
1122     // Compare scratch_cp entries to the old_cp entries that we have
1123     // already copied to *merge_cp_p. In this pass, we are eliminating
1124     // exact duplicates (matching entry at same index) so we only
1125     // compare entries in the common indice range.
1126     int increment = 1;
1127     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1128     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1129       switch (scratch_cp->tag_at(scratch_i).value()) {
1130       case JVM_CONSTANT_Double:
1131       case JVM_CONSTANT_Long:
1132         // double and long take two constant pool entries
1133         increment = 2;
1134         break;
1135 
1136       default:
1137         increment = 1;
1138         break;
1139       }
1140 
1141       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1142         scratch_i, CHECK_0);
1143       if (match) {
1144         // found a match at the same index so nothing more to do
1145         continue;
1146       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1147                                               *merge_cp_p, scratch_i)) {
1148         // The mismatch in compare_entry_to() above is because of a
1149         // resolved versus unresolved class entry at the same index
1150         // with the same string value. Since Pass 0 reverted any
1151         // class entries to unresolved class entries in *merge_cp_p,
1152         // we go with the unresolved class entry.
1153         continue;
1154       } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
1155                                                *merge_cp_p, scratch_i)) {
1156         // The mismatch in compare_entry_to() above is because of a
1157         // resolved versus unresolved string entry at the same index
1158         // with the same string value. We can live with whichever
1159         // happens to be at scratch_i in *merge_cp_p.
1160         continue;
1161       }
1162 
1163       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1164         CHECK_0);
1165       if (found_i != 0) {
1166         guarantee(found_i != scratch_i,
1167           "compare_entry_to() and find_matching_entry() do not agree");
1168 
1169         // Found a matching entry somewhere else in *merge_cp_p so
1170         // just need a mapping entry.
1171         map_index(scratch_cp, scratch_i, found_i);
1172         continue;
1173       }
1174 
1175       // The find_matching_entry() call above could fail to find a match
1176       // due to a resolved versus unresolved class or string entry situation
1177       // like we solved above with the is_unresolved_*_mismatch() calls.
1178       // However, we would have to call is_unresolved_*_mismatch() over
1179       // all of *merge_cp_p (potentially) and that doesn't seem to be
1180       // worth the time.
1181 
1182       // No match found so we have to append this entry and any unique
1183       // referenced entries to *merge_cp_p.
1184       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1185         CHECK_0);
1186     }
1187   }
1188 
1189   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1190     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1191     *merge_cp_length_p, scratch_i, _index_map_count));
1192 
1193   if (scratch_i < scratch_cp->length()) {
1194     // Pass 1b:
1195     // old_cp is smaller than scratch_cp so there are entries in
1196     // scratch_cp that we have not yet processed. We take care of
1197     // those now.
1198     int increment = 1;
1199     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1200       switch (scratch_cp->tag_at(scratch_i).value()) {
1201       case JVM_CONSTANT_Double:
1202       case JVM_CONSTANT_Long:
1203         // double and long take two constant pool entries
1204         increment = 2;
1205         break;
1206 
1207       default:
1208         increment = 1;
1209         break;
1210       }
1211 
1212       int found_i =
1213         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1214       if (found_i != 0) {
1215         // Found a matching entry somewhere else in *merge_cp_p so
1216         // just need a mapping entry.
1217         map_index(scratch_cp, scratch_i, found_i);
1218         continue;
1219       }
1220 
1221       // No match found so we have to append this entry and any unique
1222       // referenced entries to *merge_cp_p.
1223       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1224         CHECK_0);
1225     }
1226 
1227     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1228       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1229       *merge_cp_length_p, scratch_i, _index_map_count));
1230   }
1231 
1232   return true;
1233 } // end merge_constant_pools()
1234 
1235 
1236 // Merge constant pools between the_class and scratch_class and
1237 // potentially rewrite bytecodes in scratch_class to use the merged
1238 // constant pool.
1239 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1240              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1241              TRAPS) {
1242   // worst case merged constant pool length is old and new combined
1243   int merge_cp_length = the_class->constants()->length()
1244         + scratch_class->constants()->length();
1245 
1246   constantPoolHandle old_cp(THREAD, the_class->constants());
1247   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1248 
1249   // Constant pools are not easily reused so we allocate a new one
1250   // each time.
1251   // merge_cp is created unsafe for concurrent GC processing.  It
1252   // should be marked safe before discarding it. Even though
1253   // garbage,  if it crosses a card boundary, it may be scanned
1254   // in order to find the start of the first complete object on the card.
1255   constantPoolHandle merge_cp(THREAD,
1256     oopFactory::new_constantPool(merge_cp_length,
1257                                  oopDesc::IsUnsafeConc,
1258                                  THREAD));
1259   int orig_length = old_cp->orig_length();
1260   if (orig_length == 0) {
1261     // This old_cp is an actual original constant pool. We save
1262     // the original length in the merged constant pool so that
1263     // merge_constant_pools() can be more efficient. If a constant
1264     // pool has a non-zero orig_length() value, then that constant
1265     // pool was created by a merge operation in RedefineClasses.
1266     merge_cp->set_orig_length(old_cp->length());
1267   } else {
1268     // This old_cp is a merged constant pool from a previous
1269     // RedefineClasses() calls so just copy the orig_length()
1270     // value.
1271     merge_cp->set_orig_length(old_cp->orig_length());
1272   }
1273 
1274   ResourceMark rm(THREAD);
1275   _index_map_count = 0;
1276   _index_map_p = new intArray(scratch_cp->length(), -1);
1277 
1278   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1279                   &merge_cp_length, THREAD);
1280   if (!result) {
1281     // The merge can fail due to memory allocation failure or due
1282     // to robustness checks.
1283     return JVMTI_ERROR_INTERNAL;
1284   }
1285 
1286   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1287     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1288 
1289   if (_index_map_count == 0) {
1290     // there is nothing to map between the new and merged constant pools
1291 
1292     if (old_cp->length() == scratch_cp->length()) {
1293       // The old and new constant pools are the same length and the
1294       // index map is empty. This means that the three constant pools
1295       // are equivalent (but not the same). Unfortunately, the new
1296       // constant pool has not gone through link resolution nor have
1297       // the new class bytecodes gone through constant pool cache
1298       // rewriting so we can't use the old constant pool with the new
1299       // class.
1300 
1301       merge_cp()->set_is_conc_safe(true);
1302       merge_cp = constantPoolHandle();  // toss the merged constant pool
1303     } else if (old_cp->length() < scratch_cp->length()) {
1304       // The old constant pool has fewer entries than the new constant
1305       // pool and the index map is empty. This means the new constant
1306       // pool is a superset of the old constant pool. However, the old
1307       // class bytecodes have already gone through constant pool cache
1308       // rewriting so we can't use the new constant pool with the old
1309       // class.
1310 
1311       merge_cp()->set_is_conc_safe(true);
1312       merge_cp = constantPoolHandle();  // toss the merged constant pool
1313     } else {
1314       // The old constant pool has more entries than the new constant
1315       // pool and the index map is empty. This means that both the old
1316       // and merged constant pools are supersets of the new constant
1317       // pool.
1318 
1319       // Replace the new constant pool with a shrunken copy of the
1320       // merged constant pool; the previous new constant pool will
1321       // get GCed.
1322       set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1323         THREAD);
1324       // drop local ref to the merged constant pool
1325       merge_cp()->set_is_conc_safe(true);
1326       merge_cp = constantPoolHandle();
1327     }
1328   } else {
1329     if (RC_TRACE_ENABLED(0x00040000)) {
1330       // don't want to loop unless we are tracing
1331       int count = 0;
1332       for (int i = 1; i < _index_map_p->length(); i++) {
1333         int value = _index_map_p->at(i);
1334 
1335         if (value != -1) {
1336           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1337             ("index_map[%d]: old=%d new=%d", count, i, value));
1338           count++;
1339         }
1340       }
1341     }
1342 
1343     // We have entries mapped between the new and merged constant pools
1344     // so we have to rewrite some constant pool references.
1345     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1346       return JVMTI_ERROR_INTERNAL;
1347     }
1348 
1349     // Replace the new constant pool with a shrunken copy of the
1350     // merged constant pool so now the rewritten bytecodes have
1351     // valid references; the previous new constant pool will get
1352     // GCed.
1353     set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1354       THREAD);
1355     merge_cp()->set_is_conc_safe(true);
1356   }
1357   assert(old_cp()->is_conc_safe(), "Just checking");
1358   assert(scratch_cp()->is_conc_safe(), "Just checking");
1359 
1360   return JVMTI_ERROR_NONE;
1361 } // end merge_cp_and_rewrite()
1362 
1363 
1364 // Rewrite constant pool references in klass scratch_class.
1365 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1366        TRAPS) {
1367 
1368   // rewrite constant pool references in the methods:
1369   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1370     // propagate failure back to caller
1371     return false;
1372   }
1373 
1374   // rewrite constant pool references in the class_annotations:
1375   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1376     // propagate failure back to caller
1377     return false;
1378   }
1379 
1380   // rewrite constant pool references in the fields_annotations:
1381   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1382     // propagate failure back to caller
1383     return false;
1384   }
1385 
1386   // rewrite constant pool references in the methods_annotations:
1387   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1388     // propagate failure back to caller
1389     return false;
1390   }
1391 
1392   // rewrite constant pool references in the methods_parameter_annotations:
1393   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1394          THREAD)) {
1395     // propagate failure back to caller
1396     return false;
1397   }
1398 
1399   // rewrite constant pool references in the methods_default_annotations:
1400   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1401          THREAD)) {
1402     // propagate failure back to caller
1403     return false;
1404   }
1405 
1406   return true;
1407 } // end rewrite_cp_refs()
1408 
1409 
1410 // Rewrite constant pool references in the methods.
1411 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1412        instanceKlassHandle scratch_class, TRAPS) {
1413 
1414   objArrayHandle methods(THREAD, scratch_class->methods());
1415 
1416   if (methods.is_null() || methods->length() == 0) {
1417     // no methods so nothing to do
1418     return true;
1419   }
1420 
1421   // rewrite constant pool references in the methods:
1422   for (int i = methods->length() - 1; i >= 0; i--) {
1423     methodHandle method(THREAD, (methodOop)methods->obj_at(i));
1424     methodHandle new_method;
1425     rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1426     if (!new_method.is_null()) {
1427       // the method has been replaced so save the new method version
1428       methods->obj_at_put(i, new_method());
1429     }
1430   }
1431 
1432   return true;
1433 }
1434 
1435 
1436 // Rewrite constant pool references in the specific method. This code
1437 // was adapted from Rewriter::rewrite_method().
1438 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1439        methodHandle *new_method_p, TRAPS) {
1440 
1441   *new_method_p = methodHandle();  // default is no new method
1442 
1443   // We cache a pointer to the bytecodes here in code_base. If GC
1444   // moves the methodOop, then the bytecodes will also move which
1445   // will likely cause a crash. We create a No_Safepoint_Verifier
1446   // object to detect whether we pass a possible safepoint in this
1447   // code block.
1448   No_Safepoint_Verifier nsv;
1449 
1450   // Bytecodes and their length
1451   address code_base = method->code_base();
1452   int code_length = method->code_size();
1453 
1454   int bc_length;
1455   for (int bci = 0; bci < code_length; bci += bc_length) {
1456     address bcp = code_base + bci;
1457     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1458 
1459     bc_length = Bytecodes::length_for(c);
1460     if (bc_length == 0) {
1461       // More complicated bytecodes report a length of zero so
1462       // we have to try again a slightly different way.
1463       bc_length = Bytecodes::length_at(method(), bcp);
1464     }
1465 
1466     assert(bc_length != 0, "impossible bytecode length");
1467 
1468     switch (c) {
1469       case Bytecodes::_ldc:
1470       {
1471         int cp_index = *(bcp + 1);
1472         int new_index = find_new_index(cp_index);
1473 
1474         if (StressLdcRewrite && new_index == 0) {
1475           // If we are stressing ldc -> ldc_w rewriting, then we
1476           // always need a new_index value.
1477           new_index = cp_index;
1478         }
1479         if (new_index != 0) {
1480           // the original index is mapped so we have more work to do
1481           if (!StressLdcRewrite && new_index <= max_jubyte) {
1482             // The new value can still use ldc instead of ldc_w
1483             // unless we are trying to stress ldc -> ldc_w rewriting
1484             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1485               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1486               bcp, cp_index, new_index));
1487             *(bcp + 1) = new_index;
1488           } else {
1489             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1490               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1491               Bytecodes::name(c), bcp, cp_index, new_index));
1492             // the new value needs ldc_w instead of ldc
1493             u_char inst_buffer[4]; // max instruction size is 4 bytes
1494             bcp = (address)inst_buffer;
1495             // construct new instruction sequence
1496             *bcp = Bytecodes::_ldc_w;
1497             bcp++;
1498             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1499             // See comment below for difference between put_Java_u2()
1500             // and put_native_u2().
1501             Bytes::put_Java_u2(bcp, new_index);
1502 
1503             Relocator rc(method, NULL /* no RelocatorListener needed */);
1504             methodHandle m;
1505             {
1506               Pause_No_Safepoint_Verifier pnsv(&nsv);
1507 
1508               // ldc is 2 bytes and ldc_w is 3 bytes
1509               m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1510               if (m.is_null() || HAS_PENDING_EXCEPTION) {
1511                 guarantee(false, "insert_space_at() failed");
1512               }
1513             }
1514 
1515             // return the new method so that the caller can update
1516             // the containing class
1517             *new_method_p = method = m;
1518             // switch our bytecode processing loop from the old method
1519             // to the new method
1520             code_base = method->code_base();
1521             code_length = method->code_size();
1522             bcp = code_base + bci;
1523             c = (Bytecodes::Code)(*bcp);
1524             bc_length = Bytecodes::length_for(c);
1525             assert(bc_length != 0, "sanity check");
1526           } // end we need ldc_w instead of ldc
1527         } // end if there is a mapped index
1528       } break;
1529 
1530       // these bytecodes have a two-byte constant pool index
1531       case Bytecodes::_anewarray      : // fall through
1532       case Bytecodes::_checkcast      : // fall through
1533       case Bytecodes::_getfield       : // fall through
1534       case Bytecodes::_getstatic      : // fall through
1535       case Bytecodes::_instanceof     : // fall through
1536       case Bytecodes::_invokeinterface: // fall through
1537       case Bytecodes::_invokespecial  : // fall through
1538       case Bytecodes::_invokestatic   : // fall through
1539       case Bytecodes::_invokevirtual  : // fall through
1540       case Bytecodes::_ldc_w          : // fall through
1541       case Bytecodes::_ldc2_w         : // fall through
1542       case Bytecodes::_multianewarray : // fall through
1543       case Bytecodes::_new            : // fall through
1544       case Bytecodes::_putfield       : // fall through
1545       case Bytecodes::_putstatic      :
1546       {
1547         address p = bcp + 1;
1548         int cp_index = Bytes::get_Java_u2(p);
1549         int new_index = find_new_index(cp_index);
1550         if (new_index != 0) {
1551           // the original index is mapped so update w/ new value
1552           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1553             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1554             bcp, cp_index, new_index));
1555           // Rewriter::rewrite_method() uses put_native_u2() in this
1556           // situation because it is reusing the constant pool index
1557           // location for a native index into the constantPoolCache.
1558           // Since we are updating the constant pool index prior to
1559           // verification and constantPoolCache initialization, we
1560           // need to keep the new index in Java byte order.
1561           Bytes::put_Java_u2(p, new_index);
1562         }
1563       } break;
1564     }
1565   } // end for each bytecode
1566 } // end rewrite_cp_refs_in_method()
1567 
1568 
1569 // Rewrite constant pool references in the class_annotations field.
1570 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1571        instanceKlassHandle scratch_class, TRAPS) {
1572 
1573   typeArrayHandle class_annotations(THREAD,
1574     scratch_class->class_annotations());
1575   if (class_annotations.is_null() || class_annotations->length() == 0) {
1576     // no class_annotations so nothing to do
1577     return true;
1578   }
1579 
1580   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1581     ("class_annotations length=%d", class_annotations->length()));
1582 
1583   int byte_i = 0;  // byte index into class_annotations
1584   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1585            THREAD);
1586 }
1587 
1588 
1589 // Rewrite constant pool references in an annotations typeArray. This
1590 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1591 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1592 //
1593 // annotations_typeArray {
1594 //   u2 num_annotations;
1595 //   annotation annotations[num_annotations];
1596 // }
1597 //
1598 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1599        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1600 
1601   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1602     // not enough room for num_annotations field
1603     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1604       ("length() is too small for num_annotations field"));
1605     return false;
1606   }
1607 
1608   u2 num_annotations = Bytes::get_Java_u2((address)
1609                          annotations_typeArray->byte_at_addr(byte_i_ref));
1610   byte_i_ref += 2;
1611 
1612   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1613     ("num_annotations=%d", num_annotations));
1614 
1615   int calc_num_annotations = 0;
1616   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1617     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1618            byte_i_ref, THREAD)) {
1619       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1620         ("bad annotation_struct at %d", calc_num_annotations));
1621       // propagate failure back to caller
1622       return false;
1623     }
1624   }
1625   assert(num_annotations == calc_num_annotations, "sanity check");
1626 
1627   return true;
1628 } // end rewrite_cp_refs_in_annotations_typeArray()
1629 
1630 
1631 // Rewrite constant pool references in the annotation struct portion of
1632 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1633 // the 2nd-edition of the VM spec:
1634 //
1635 // struct annotation {
1636 //   u2 type_index;
1637 //   u2 num_element_value_pairs;
1638 //   {
1639 //     u2 element_name_index;
1640 //     element_value value;
1641 //   } element_value_pairs[num_element_value_pairs];
1642 // }
1643 //
1644 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1645        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1646   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1647     // not enough room for smallest annotation_struct
1648     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1649       ("length() is too small for annotation_struct"));
1650     return false;
1651   }
1652 
1653   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1654                     byte_i_ref, "mapped old type_index=%d", THREAD);
1655 
1656   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1657                                  annotations_typeArray->byte_at_addr(
1658                                  byte_i_ref));
1659   byte_i_ref += 2;
1660 
1661   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1662     ("type_index=%d  num_element_value_pairs=%d", type_index,
1663     num_element_value_pairs));
1664 
1665   int calc_num_element_value_pairs = 0;
1666   for (; calc_num_element_value_pairs < num_element_value_pairs;
1667        calc_num_element_value_pairs++) {
1668     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1669       // not enough room for another element_name_index, let alone
1670       // the rest of another component
1671       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1672         ("length() is too small for element_name_index"));
1673       return false;
1674     }
1675 
1676     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1677                               annotations_typeArray, byte_i_ref,
1678                               "mapped old element_name_index=%d", THREAD);
1679 
1680     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1681       ("element_name_index=%d", element_name_index));
1682 
1683     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1684            byte_i_ref, THREAD)) {
1685       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1686         ("bad element_value at %d", calc_num_element_value_pairs));
1687       // propagate failure back to caller
1688       return false;
1689     }
1690   } // end for each component
1691   assert(num_element_value_pairs == calc_num_element_value_pairs,
1692     "sanity check");
1693 
1694   return true;
1695 } // end rewrite_cp_refs_in_annotation_struct()
1696 
1697 
1698 // Rewrite a constant pool reference at the current position in
1699 // annotations_typeArray if needed. Returns the original constant
1700 // pool reference if a rewrite was not needed or the new constant
1701 // pool reference if a rewrite was needed.
1702 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1703      typeArrayHandle annotations_typeArray, int &byte_i_ref,
1704      const char * trace_mesg, TRAPS) {
1705 
1706   address cp_index_addr = (address)
1707     annotations_typeArray->byte_at_addr(byte_i_ref);
1708   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1709   u2 new_cp_index = find_new_index(old_cp_index);
1710   if (new_cp_index != 0) {
1711     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1712     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1713     old_cp_index = new_cp_index;
1714   }
1715   byte_i_ref += 2;
1716   return old_cp_index;
1717 }
1718 
1719 
1720 // Rewrite constant pool references in the element_value portion of an
1721 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1722 // the 2nd-edition of the VM spec:
1723 //
1724 // struct element_value {
1725 //   u1 tag;
1726 //   union {
1727 //     u2 const_value_index;
1728 //     {
1729 //       u2 type_name_index;
1730 //       u2 const_name_index;
1731 //     } enum_const_value;
1732 //     u2 class_info_index;
1733 //     annotation annotation_value;
1734 //     struct {
1735 //       u2 num_values;
1736 //       element_value values[num_values];
1737 //     } array_value;
1738 //   } value;
1739 // }
1740 //
1741 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1742        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1743 
1744   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1745     // not enough room for a tag let alone the rest of an element_value
1746     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1747       ("length() is too small for a tag"));
1748     return false;
1749   }
1750 
1751   u1 tag = annotations_typeArray->byte_at(byte_i_ref);
1752   byte_i_ref++;
1753   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1754 
1755   switch (tag) {
1756     // These BaseType tag values are from Table 4.2 in VM spec:
1757     case 'B':  // byte
1758     case 'C':  // char
1759     case 'D':  // double
1760     case 'F':  // float
1761     case 'I':  // int
1762     case 'J':  // long
1763     case 'S':  // short
1764     case 'Z':  // boolean
1765 
1766     // The remaining tag values are from Table 4.8 in the 2nd-edition of
1767     // the VM spec:
1768     case 's':
1769     {
1770       // For the above tag values (including the BaseType values),
1771       // value.const_value_index is right union field.
1772 
1773       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1774         // not enough room for a const_value_index
1775         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1776           ("length() is too small for a const_value_index"));
1777         return false;
1778       }
1779 
1780       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1781                                annotations_typeArray, byte_i_ref,
1782                                "mapped old const_value_index=%d", THREAD);
1783 
1784       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1785         ("const_value_index=%d", const_value_index));
1786     } break;
1787 
1788     case 'e':
1789     {
1790       // for the above tag value, value.enum_const_value is right union field
1791 
1792       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1793         // not enough room for a enum_const_value
1794         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1795           ("length() is too small for a enum_const_value"));
1796         return false;
1797       }
1798 
1799       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1800                              annotations_typeArray, byte_i_ref,
1801                              "mapped old type_name_index=%d", THREAD);
1802 
1803       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1804                               annotations_typeArray, byte_i_ref,
1805                               "mapped old const_name_index=%d", THREAD);
1806 
1807       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1808         ("type_name_index=%d  const_name_index=%d", type_name_index,
1809         const_name_index));
1810     } break;
1811 
1812     case 'c':
1813     {
1814       // for the above tag value, value.class_info_index is right union field
1815 
1816       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1817         // not enough room for a class_info_index
1818         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1819           ("length() is too small for a class_info_index"));
1820         return false;
1821       }
1822 
1823       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1824                               annotations_typeArray, byte_i_ref,
1825                               "mapped old class_info_index=%d", THREAD);
1826 
1827       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1828         ("class_info_index=%d", class_info_index));
1829     } break;
1830 
1831     case '@':
1832       // For the above tag value, value.attr_value is the right union
1833       // field. This is a nested annotation.
1834       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1835              byte_i_ref, THREAD)) {
1836         // propagate failure back to caller
1837         return false;
1838       }
1839       break;
1840 
1841     case '[':
1842     {
1843       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1844         // not enough room for a num_values field
1845         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1846           ("length() is too small for a num_values field"));
1847         return false;
1848       }
1849 
1850       // For the above tag value, value.array_value is the right union
1851       // field. This is an array of nested element_value.
1852       u2 num_values = Bytes::get_Java_u2((address)
1853                         annotations_typeArray->byte_at_addr(byte_i_ref));
1854       byte_i_ref += 2;
1855       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1856 
1857       int calc_num_values = 0;
1858       for (; calc_num_values < num_values; calc_num_values++) {
1859         if (!rewrite_cp_refs_in_element_value(
1860                annotations_typeArray, byte_i_ref, THREAD)) {
1861           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1862             ("bad nested element_value at %d", calc_num_values));
1863           // propagate failure back to caller
1864           return false;
1865         }
1866       }
1867       assert(num_values == calc_num_values, "sanity check");
1868     } break;
1869 
1870     default:
1871       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1872       return false;
1873   } // end decode tag field
1874 
1875   return true;
1876 } // end rewrite_cp_refs_in_element_value()
1877 
1878 
1879 // Rewrite constant pool references in a fields_annotations field.
1880 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1881        instanceKlassHandle scratch_class, TRAPS) {
1882 
1883   objArrayHandle fields_annotations(THREAD,
1884     scratch_class->fields_annotations());
1885 
1886   if (fields_annotations.is_null() || fields_annotations->length() == 0) {
1887     // no fields_annotations so nothing to do
1888     return true;
1889   }
1890 
1891   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1892     ("fields_annotations length=%d", fields_annotations->length()));
1893 
1894   for (int i = 0; i < fields_annotations->length(); i++) {
1895     typeArrayHandle field_annotations(THREAD,
1896       (typeArrayOop)fields_annotations->obj_at(i));
1897     if (field_annotations.is_null() || field_annotations->length() == 0) {
1898       // this field does not have any annotations so skip it
1899       continue;
1900     }
1901 
1902     int byte_i = 0;  // byte index into field_annotations
1903     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1904            THREAD)) {
1905       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1906         ("bad field_annotations at %d", i));
1907       // propagate failure back to caller
1908       return false;
1909     }
1910   }
1911 
1912   return true;
1913 } // end rewrite_cp_refs_in_fields_annotations()
1914 
1915 
1916 // Rewrite constant pool references in a methods_annotations field.
1917 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1918        instanceKlassHandle scratch_class, TRAPS) {
1919 
1920   objArrayHandle methods_annotations(THREAD,
1921     scratch_class->methods_annotations());
1922 
1923   if (methods_annotations.is_null() || methods_annotations->length() == 0) {
1924     // no methods_annotations so nothing to do
1925     return true;
1926   }
1927 
1928   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1929     ("methods_annotations length=%d", methods_annotations->length()));
1930 
1931   for (int i = 0; i < methods_annotations->length(); i++) {
1932     typeArrayHandle method_annotations(THREAD,
1933       (typeArrayOop)methods_annotations->obj_at(i));
1934     if (method_annotations.is_null() || method_annotations->length() == 0) {
1935       // this method does not have any annotations so skip it
1936       continue;
1937     }
1938 
1939     int byte_i = 0;  // byte index into method_annotations
1940     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
1941            THREAD)) {
1942       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1943         ("bad method_annotations at %d", i));
1944       // propagate failure back to caller
1945       return false;
1946     }
1947   }
1948 
1949   return true;
1950 } // end rewrite_cp_refs_in_methods_annotations()
1951 
1952 
1953 // Rewrite constant pool references in a methods_parameter_annotations
1954 // field. This "structure" is adapted from the
1955 // RuntimeVisibleParameterAnnotations_attribute described in section
1956 // 4.8.17 of the 2nd-edition of the VM spec:
1957 //
1958 // methods_parameter_annotations_typeArray {
1959 //   u1 num_parameters;
1960 //   {
1961 //     u2 num_annotations;
1962 //     annotation annotations[num_annotations];
1963 //   } parameter_annotations[num_parameters];
1964 // }
1965 //
1966 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
1967        instanceKlassHandle scratch_class, TRAPS) {
1968 
1969   objArrayHandle methods_parameter_annotations(THREAD,
1970     scratch_class->methods_parameter_annotations());
1971 
1972   if (methods_parameter_annotations.is_null()
1973       || methods_parameter_annotations->length() == 0) {
1974     // no methods_parameter_annotations so nothing to do
1975     return true;
1976   }
1977 
1978   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1979     ("methods_parameter_annotations length=%d",
1980     methods_parameter_annotations->length()));
1981 
1982   for (int i = 0; i < methods_parameter_annotations->length(); i++) {
1983     typeArrayHandle method_parameter_annotations(THREAD,
1984       (typeArrayOop)methods_parameter_annotations->obj_at(i));
1985     if (method_parameter_annotations.is_null()
1986         || method_parameter_annotations->length() == 0) {
1987       // this method does not have any parameter annotations so skip it
1988       continue;
1989     }
1990 
1991     if (method_parameter_annotations->length() < 1) {
1992       // not enough room for a num_parameters field
1993       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1994         ("length() is too small for a num_parameters field at %d", i));
1995       return false;
1996     }
1997 
1998     int byte_i = 0;  // byte index into method_parameter_annotations
1999 
2000     u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
2001     byte_i++;
2002 
2003     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2004       ("num_parameters=%d", num_parameters));
2005 
2006     int calc_num_parameters = 0;
2007     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2008       if (!rewrite_cp_refs_in_annotations_typeArray(
2009              method_parameter_annotations, byte_i, THREAD)) {
2010         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2011           ("bad method_parameter_annotations at %d", calc_num_parameters));
2012         // propagate failure back to caller
2013         return false;
2014       }
2015     }
2016     assert(num_parameters == calc_num_parameters, "sanity check");
2017   }
2018 
2019   return true;
2020 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2021 
2022 
2023 // Rewrite constant pool references in a methods_default_annotations
2024 // field. This "structure" is adapted from the AnnotationDefault_attribute
2025 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2026 //
2027 // methods_default_annotations_typeArray {
2028 //   element_value default_value;
2029 // }
2030 //
2031 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2032        instanceKlassHandle scratch_class, TRAPS) {
2033 
2034   objArrayHandle methods_default_annotations(THREAD,
2035     scratch_class->methods_default_annotations());
2036 
2037   if (methods_default_annotations.is_null()
2038       || methods_default_annotations->length() == 0) {
2039     // no methods_default_annotations so nothing to do
2040     return true;
2041   }
2042 
2043   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2044     ("methods_default_annotations length=%d",
2045     methods_default_annotations->length()));
2046 
2047   for (int i = 0; i < methods_default_annotations->length(); i++) {
2048     typeArrayHandle method_default_annotations(THREAD,
2049       (typeArrayOop)methods_default_annotations->obj_at(i));
2050     if (method_default_annotations.is_null()
2051         || method_default_annotations->length() == 0) {
2052       // this method does not have any default annotations so skip it
2053       continue;
2054     }
2055 
2056     int byte_i = 0;  // byte index into method_default_annotations
2057 
2058     if (!rewrite_cp_refs_in_element_value(
2059            method_default_annotations, byte_i, THREAD)) {
2060       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2061         ("bad default element_value at %d", i));
2062       // propagate failure back to caller
2063       return false;
2064     }
2065   }
2066 
2067   return true;
2068 } // end rewrite_cp_refs_in_methods_default_annotations()
2069 
2070 
2071 // Rewrite constant pool references in the method's stackmap table.
2072 // These "structures" are adapted from the StackMapTable_attribute that
2073 // is described in section 4.8.4 of the 6.0 version of the VM spec
2074 // (dated 2005.10.26):
2075 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2076 //
2077 // stack_map {
2078 //   u2 number_of_entries;
2079 //   stack_map_frame entries[number_of_entries];
2080 // }
2081 //
2082 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2083        methodHandle method, TRAPS) {
2084 
2085   if (!method->has_stackmap_table()) {
2086     return;
2087   }
2088 
2089   typeArrayOop stackmap_data = method->stackmap_data();
2090   address stackmap_p = (address)stackmap_data->byte_at_addr(0);
2091   address stackmap_end = stackmap_p + stackmap_data->length();
2092 
2093   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2094   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2095   stackmap_p += 2;
2096 
2097   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2098     ("number_of_entries=%u", number_of_entries));
2099 
2100   // walk through each stack_map_frame
2101   u2 calc_number_of_entries = 0;
2102   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2103     // The stack_map_frame structure is a u1 frame_type followed by
2104     // 0 or more bytes of data:
2105     //
2106     // union stack_map_frame {
2107     //   same_frame;
2108     //   same_locals_1_stack_item_frame;
2109     //   same_locals_1_stack_item_frame_extended;
2110     //   chop_frame;
2111     //   same_frame_extended;
2112     //   append_frame;
2113     //   full_frame;
2114     // }
2115 
2116     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2117     // The Linux compiler does not like frame_type to be u1 or u2. It
2118     // issues the following warning for the first if-statement below:
2119     //
2120     // "warning: comparison is always true due to limited range of data type"
2121     //
2122     u4 frame_type = *stackmap_p;
2123     stackmap_p++;
2124 
2125     // same_frame {
2126     //   u1 frame_type = SAME; /* 0-63 */
2127     // }
2128     if (frame_type >= 0 && frame_type <= 63) {
2129       // nothing more to do for same_frame
2130     }
2131 
2132     // same_locals_1_stack_item_frame {
2133     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2134     //   verification_type_info stack[1];
2135     // }
2136     else if (frame_type >= 64 && frame_type <= 127) {
2137       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2138         calc_number_of_entries, frame_type, THREAD);
2139     }
2140 
2141     // reserved for future use
2142     else if (frame_type >= 128 && frame_type <= 246) {
2143       // nothing more to do for reserved frame_types
2144     }
2145 
2146     // same_locals_1_stack_item_frame_extended {
2147     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2148     //   u2 offset_delta;
2149     //   verification_type_info stack[1];
2150     // }
2151     else if (frame_type == 247) {
2152       stackmap_p += 2;
2153       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2154         calc_number_of_entries, frame_type, THREAD);
2155     }
2156 
2157     // chop_frame {
2158     //   u1 frame_type = CHOP; /* 248-250 */
2159     //   u2 offset_delta;
2160     // }
2161     else if (frame_type >= 248 && frame_type <= 250) {
2162       stackmap_p += 2;
2163     }
2164 
2165     // same_frame_extended {
2166     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2167     //   u2 offset_delta;
2168     // }
2169     else if (frame_type == 251) {
2170       stackmap_p += 2;
2171     }
2172 
2173     // append_frame {
2174     //   u1 frame_type = APPEND; /* 252-254 */
2175     //   u2 offset_delta;
2176     //   verification_type_info locals[frame_type - 251];
2177     // }
2178     else if (frame_type >= 252 && frame_type <= 254) {
2179       assert(stackmap_p + 2 <= stackmap_end,
2180         "no room for offset_delta");
2181       stackmap_p += 2;
2182       u1 len = frame_type - 251;
2183       for (u1 i = 0; i < len; i++) {
2184         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2185           calc_number_of_entries, frame_type, THREAD);
2186       }
2187     }
2188 
2189     // full_frame {
2190     //   u1 frame_type = FULL_FRAME; /* 255 */
2191     //   u2 offset_delta;
2192     //   u2 number_of_locals;
2193     //   verification_type_info locals[number_of_locals];
2194     //   u2 number_of_stack_items;
2195     //   verification_type_info stack[number_of_stack_items];
2196     // }
2197     else if (frame_type == 255) {
2198       assert(stackmap_p + 2 + 2 <= stackmap_end,
2199         "no room for smallest full_frame");
2200       stackmap_p += 2;
2201 
2202       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2203       stackmap_p += 2;
2204 
2205       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2206         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2207           calc_number_of_entries, frame_type, THREAD);
2208       }
2209 
2210       // Use the largest size for the number_of_stack_items, but only get
2211       // the right number of bytes.
2212       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2213       stackmap_p += 2;
2214 
2215       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2216         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2217           calc_number_of_entries, frame_type, THREAD);
2218       }
2219     }
2220   } // end while there is a stack_map_frame
2221   assert(number_of_entries == calc_number_of_entries, "sanity check");
2222 } // end rewrite_cp_refs_in_stack_map_table()
2223 
2224 
2225 // Rewrite constant pool references in the verification type info
2226 // portion of the method's stackmap table. These "structures" are
2227 // adapted from the StackMapTable_attribute that is described in
2228 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2229 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2230 //
2231 // The verification_type_info structure is a u1 tag followed by 0 or
2232 // more bytes of data:
2233 //
2234 // union verification_type_info {
2235 //   Top_variable_info;
2236 //   Integer_variable_info;
2237 //   Float_variable_info;
2238 //   Long_variable_info;
2239 //   Double_variable_info;
2240 //   Null_variable_info;
2241 //   UninitializedThis_variable_info;
2242 //   Object_variable_info;
2243 //   Uninitialized_variable_info;
2244 // }
2245 //
2246 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2247        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2248        u1 frame_type, TRAPS) {
2249 
2250   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2251   u1 tag = *stackmap_p_ref;
2252   stackmap_p_ref++;
2253 
2254   switch (tag) {
2255   // Top_variable_info {
2256   //   u1 tag = ITEM_Top; /* 0 */
2257   // }
2258   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2259   case 0:  // fall through
2260 
2261   // Integer_variable_info {
2262   //   u1 tag = ITEM_Integer; /* 1 */
2263   // }
2264   case ITEM_Integer:  // fall through
2265 
2266   // Float_variable_info {
2267   //   u1 tag = ITEM_Float; /* 2 */
2268   // }
2269   case ITEM_Float:  // fall through
2270 
2271   // Double_variable_info {
2272   //   u1 tag = ITEM_Double; /* 3 */
2273   // }
2274   case ITEM_Double:  // fall through
2275 
2276   // Long_variable_info {
2277   //   u1 tag = ITEM_Long; /* 4 */
2278   // }
2279   case ITEM_Long:  // fall through
2280 
2281   // Null_variable_info {
2282   //   u1 tag = ITEM_Null; /* 5 */
2283   // }
2284   case ITEM_Null:  // fall through
2285 
2286   // UninitializedThis_variable_info {
2287   //   u1 tag = ITEM_UninitializedThis; /* 6 */
2288   // }
2289   case ITEM_UninitializedThis:
2290     // nothing more to do for the above tag types
2291     break;
2292 
2293   // Object_variable_info {
2294   //   u1 tag = ITEM_Object; /* 7 */
2295   //   u2 cpool_index;
2296   // }
2297   case ITEM_Object:
2298   {
2299     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2300     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2301     u2 new_cp_index = find_new_index(cpool_index);
2302     if (new_cp_index != 0) {
2303       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2304         ("mapped old cpool_index=%d", cpool_index));
2305       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2306       cpool_index = new_cp_index;
2307     }
2308     stackmap_p_ref += 2;
2309 
2310     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2311       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2312       frame_type, cpool_index));
2313   } break;
2314 
2315   // Uninitialized_variable_info {
2316   //   u1 tag = ITEM_Uninitialized; /* 8 */
2317   //   u2 offset;
2318   // }
2319   case ITEM_Uninitialized:
2320     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2321     stackmap_p_ref += 2;
2322     break;
2323 
2324   default:
2325     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2326       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2327     ShouldNotReachHere();
2328     break;
2329   } // end switch (tag)
2330 } // end rewrite_cp_refs_in_verification_type_info()
2331 
2332 
2333 // Change the constant pool associated with klass scratch_class to
2334 // scratch_cp. If shrink is true, then scratch_cp_length elements
2335 // are copied from scratch_cp to a smaller constant pool and the
2336 // smaller constant pool is associated with scratch_class.
2337 void VM_RedefineClasses::set_new_constant_pool(
2338        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2339        int scratch_cp_length, bool shrink, TRAPS) {
2340   assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
2341 
2342   if (shrink) {
2343     // scratch_cp is a merged constant pool and has enough space for a
2344     // worst case merge situation. We want to associate the minimum
2345     // sized constant pool with the klass to save space.
2346     constantPoolHandle smaller_cp(THREAD,
2347       oopFactory::new_constantPool(scratch_cp_length,
2348                                    oopDesc::IsUnsafeConc,
2349                                    THREAD));
2350     // preserve orig_length() value in the smaller copy
2351     int orig_length = scratch_cp->orig_length();
2352     assert(orig_length != 0, "sanity check");
2353     smaller_cp->set_orig_length(orig_length);
2354     scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2355     scratch_cp = smaller_cp;
2356     smaller_cp()->set_is_conc_safe(true);
2357   }
2358 
2359   // attach new constant pool to klass
2360   scratch_cp->set_pool_holder(scratch_class());
2361 
2362   // attach klass to new constant pool
2363   scratch_class->set_constants(scratch_cp());
2364 
2365   int i;  // for portability
2366 
2367   // update each field in klass to use new constant pool indices as needed
2368   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
2369     jshort cur_index = fs.name_index();
2370     jshort new_index = find_new_index(cur_index);
2371     if (new_index != 0) {
2372       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2373         ("field-name_index change: %d to %d", cur_index, new_index));
2374       fs.set_name_index(new_index);
2375     }
2376     cur_index = fs.signature_index();
2377     new_index = find_new_index(cur_index);
2378     if (new_index != 0) {
2379       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2380         ("field-signature_index change: %d to %d", cur_index, new_index));
2381       fs.set_signature_index(new_index);
2382     }
2383     cur_index = fs.initval_index();
2384     new_index = find_new_index(cur_index);
2385     if (new_index != 0) {
2386       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2387         ("field-initval_index change: %d to %d", cur_index, new_index));
2388       fs.set_initval_index(new_index);
2389     }
2390     cur_index = fs.generic_signature_index();
2391     new_index = find_new_index(cur_index);
2392     if (new_index != 0) {
2393       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2394         ("field-generic_signature change: %d to %d", cur_index, new_index));
2395       fs.set_generic_signature_index(new_index);
2396     }
2397   } // end for each field
2398 
2399   // Update constant pool indices in the inner classes info to use
2400   // new constant indices as needed. The inner classes info is a
2401   // quadruple:
2402   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2403   typeArrayOop inner_class_list = scratch_class->inner_classes();
2404   int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
2405   if (icl_length > 0) {
2406     typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
2407     for (int i = 0; i < icl_length;
2408          i += instanceKlass::inner_class_next_offset) {
2409       int cur_index = inner_class_list_h->ushort_at(i
2410                         + instanceKlass::inner_class_inner_class_info_offset);
2411       if (cur_index == 0) {
2412         continue;  // JVM spec. allows null inner class refs so skip it
2413       }
2414       int new_index = find_new_index(cur_index);
2415       if (new_index != 0) {
2416         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2417           ("inner_class_info change: %d to %d", cur_index, new_index));
2418         inner_class_list_h->ushort_at_put(i
2419           + instanceKlass::inner_class_inner_class_info_offset, new_index);
2420       }
2421       cur_index = inner_class_list_h->ushort_at(i
2422                     + instanceKlass::inner_class_outer_class_info_offset);
2423       new_index = find_new_index(cur_index);
2424       if (new_index != 0) {
2425         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2426           ("outer_class_info change: %d to %d", cur_index, new_index));
2427         inner_class_list_h->ushort_at_put(i
2428           + instanceKlass::inner_class_outer_class_info_offset, new_index);
2429       }
2430       cur_index = inner_class_list_h->ushort_at(i
2431                     + instanceKlass::inner_class_inner_name_offset);
2432       new_index = find_new_index(cur_index);
2433       if (new_index != 0) {
2434         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2435           ("inner_name change: %d to %d", cur_index, new_index));
2436         inner_class_list_h->ushort_at_put(i
2437           + instanceKlass::inner_class_inner_name_offset, new_index);
2438       }
2439     } // end for each inner class
2440   } // end if we have inner classes
2441 
2442   // Attach each method in klass to the new constant pool and update
2443   // to use new constant pool indices as needed:
2444   objArrayHandle methods(THREAD, scratch_class->methods());
2445   for (i = methods->length() - 1; i >= 0; i--) {
2446     methodHandle method(THREAD, (methodOop)methods->obj_at(i));
2447     method->set_constants(scratch_cp());
2448 
2449     int new_index = find_new_index(method->name_index());
2450     if (new_index != 0) {
2451       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2452         ("method-name_index change: %d to %d", method->name_index(),
2453         new_index));
2454       method->set_name_index(new_index);
2455     }
2456     new_index = find_new_index(method->signature_index());
2457     if (new_index != 0) {
2458       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2459         ("method-signature_index change: %d to %d",
2460         method->signature_index(), new_index));
2461       method->set_signature_index(new_index);
2462     }
2463     new_index = find_new_index(method->generic_signature_index());
2464     if (new_index != 0) {
2465       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2466         ("method-generic_signature_index change: %d to %d",
2467         method->generic_signature_index(), new_index));
2468       method->set_generic_signature_index(new_index);
2469     }
2470 
2471     // Update constant pool indices in the method's checked exception
2472     // table to use new constant indices as needed.
2473     int cext_length = method->checked_exceptions_length();
2474     if (cext_length > 0) {
2475       CheckedExceptionElement * cext_table =
2476         method->checked_exceptions_start();
2477       for (int j = 0; j < cext_length; j++) {
2478         int cur_index = cext_table[j].class_cp_index;
2479         int new_index = find_new_index(cur_index);
2480         if (new_index != 0) {
2481           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2482             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
2483           cext_table[j].class_cp_index = (u2)new_index;
2484         }
2485       } // end for each checked exception table entry
2486     } // end if there are checked exception table entries
2487 
2488     // Update each catch type index in the method's exception table
2489     // to use new constant pool indices as needed. The exception table
2490     // holds quadruple entries of the form:
2491     //   (beg_bci, end_bci, handler_bci, klass_index)
2492     const int beg_bci_offset     = 0;
2493     const int end_bci_offset     = 1;
2494     const int handler_bci_offset = 2;
2495     const int klass_index_offset = 3;
2496     const int entry_size         = 4;
2497 
2498     typeArrayHandle ex_table (THREAD, method->exception_table());
2499     int ext_length = ex_table->length();
2500     assert(ext_length % entry_size == 0, "exception table format has changed");
2501 
2502     for (int j = 0; j < ext_length; j += entry_size) {
2503       int cur_index = ex_table->int_at(j + klass_index_offset);
2504       int new_index = find_new_index(cur_index);
2505       if (new_index != 0) {
2506         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2507           ("ext-klass_index change: %d to %d", cur_index, new_index));
2508         ex_table->int_at_put(j + klass_index_offset, new_index);
2509       }
2510     } // end for each exception table entry
2511 
2512     // Update constant pool indices in the method's local variable
2513     // table to use new constant indices as needed. The local variable
2514     // table hold sextuple entries of the form:
2515     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2516     int lvt_length = method->localvariable_table_length();
2517     if (lvt_length > 0) {
2518       LocalVariableTableElement * lv_table =
2519         method->localvariable_table_start();
2520       for (int j = 0; j < lvt_length; j++) {
2521         int cur_index = lv_table[j].name_cp_index;
2522         int new_index = find_new_index(cur_index);
2523         if (new_index != 0) {
2524           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2525             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2526           lv_table[j].name_cp_index = (u2)new_index;
2527         }
2528         cur_index = lv_table[j].descriptor_cp_index;
2529         new_index = find_new_index(cur_index);
2530         if (new_index != 0) {
2531           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2532             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2533             new_index));
2534           lv_table[j].descriptor_cp_index = (u2)new_index;
2535         }
2536         cur_index = lv_table[j].signature_cp_index;
2537         new_index = find_new_index(cur_index);
2538         if (new_index != 0) {
2539           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2540             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2541           lv_table[j].signature_cp_index = (u2)new_index;
2542         }
2543       } // end for each local variable table entry
2544     } // end if there are local variable table entries
2545 
2546     rewrite_cp_refs_in_stack_map_table(method, THREAD);
2547   } // end for each method
2548   assert(scratch_cp()->is_conc_safe(), "Just checking");
2549 } // end set_new_constant_pool()
2550 
2551 
2552 // Unevolving classes may point to methods of the_class directly
2553 // from their constant pool caches, itables, and/or vtables. We
2554 // use the SystemDictionary::classes_do() facility and this helper
2555 // to fix up these pointers.
2556 //
2557 // Note: We currently don't support updating the vtable in
2558 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2559 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
2560        oop initiating_loader, TRAPS) {
2561   Klass *k = k_oop->klass_part();
2562   if (k->oop_is_instance()) {
2563     HandleMark hm(THREAD);
2564     instanceKlass *ik = (instanceKlass *) k;
2565 
2566     // HotSpot specific optimization! HotSpot does not currently
2567     // support delegation from the bootstrap class loader to a
2568     // user-defined class loader. This means that if the bootstrap
2569     // class loader is the initiating class loader, then it will also
2570     // be the defining class loader. This also means that classes
2571     // loaded by the bootstrap class loader cannot refer to classes
2572     // loaded by a user-defined class loader. Note: a user-defined
2573     // class loader can delegate to the bootstrap class loader.
2574     //
2575     // If the current class being redefined has a user-defined class
2576     // loader as its defining class loader, then we can skip all
2577     // classes loaded by the bootstrap class loader.
2578     bool is_user_defined =
2579            instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2580     if (is_user_defined && ik->class_loader() == NULL) {
2581       return;
2582     }
2583 
2584     // This is a very busy routine. We don't want too much tracing
2585     // printed out.
2586     bool trace_name_printed = false;
2587 
2588     // Very noisy: only enable this call if you are trying to determine
2589     // that a specific class gets found by this routine.
2590     // RC_TRACE macro has an embedded ResourceMark
2591     // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2592     //   ("adjust check: name=%s", ik->external_name()));
2593     // trace_name_printed = true;
2594 
2595     // Fix the vtable embedded in the_class and subclasses of the_class,
2596     // if one exists. We discard scratch_class and we don't keep an
2597     // instanceKlass around to hold obsolete methods so we don't have
2598     // any other instanceKlass embedded vtables to update. The vtable
2599     // holds the methodOops for virtual (but not final) methods.
2600     if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2601       // ik->vtable() creates a wrapper object; rm cleans it up
2602       ResourceMark rm(THREAD);
2603       ik->vtable()->adjust_method_entries(_matching_old_methods,
2604                                           _matching_new_methods,
2605                                           _matching_methods_length,
2606                                           &trace_name_printed);
2607     }
2608 
2609     // If the current class has an itable and we are either redefining an
2610     // interface or if the current class is a subclass of the_class, then
2611     // we potentially have to fix the itable. If we are redefining an
2612     // interface, then we have to call adjust_method_entries() for
2613     // every instanceKlass that has an itable since there isn't a
2614     // subclass relationship between an interface and an instanceKlass.
2615     if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
2616         || ik->is_subclass_of(_the_class_oop))) {
2617       // ik->itable() creates a wrapper object; rm cleans it up
2618       ResourceMark rm(THREAD);
2619       ik->itable()->adjust_method_entries(_matching_old_methods,
2620                                           _matching_new_methods,
2621                                           _matching_methods_length,
2622                                           &trace_name_printed);
2623     }
2624 
2625     // The constant pools in other classes (other_cp) can refer to
2626     // methods in the_class. We have to update method information in
2627     // other_cp's cache. If other_cp has a previous version, then we
2628     // have to repeat the process for each previous version. The
2629     // constant pool cache holds the methodOops for non-virtual
2630     // methods and for virtual, final methods.
2631     //
2632     // Special case: if the current class is the_class, then new_cp
2633     // has already been attached to the_class and old_cp has already
2634     // been added as a previous version. The new_cp doesn't have any
2635     // cached references to old methods so it doesn't need to be
2636     // updated. We can simply start with the previous version(s) in
2637     // that case.
2638     constantPoolHandle other_cp;
2639     constantPoolCacheOop cp_cache;
2640 
2641     if (k_oop != _the_class_oop) {
2642       // this klass' constant pool cache may need adjustment
2643       other_cp = constantPoolHandle(ik->constants());
2644       cp_cache = other_cp->cache();
2645       if (cp_cache != NULL) {
2646         cp_cache->adjust_method_entries(_matching_old_methods,
2647                                         _matching_new_methods,
2648                                         _matching_methods_length,
2649                                         &trace_name_printed);
2650       }
2651     }
2652     {
2653       ResourceMark rm(THREAD);
2654       // PreviousVersionInfo objects returned via PreviousVersionWalker
2655       // contain a GrowableArray of handles. We have to clean up the
2656       // GrowableArray _after_ the PreviousVersionWalker destructor
2657       // has destroyed the handles.
2658       {
2659         // the previous versions' constant pool caches may need adjustment
2660         PreviousVersionWalker pvw(ik);
2661         for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2662              pv_info != NULL; pv_info = pvw.next_previous_version()) {
2663           other_cp = pv_info->prev_constant_pool_handle();
2664           cp_cache = other_cp->cache();
2665           if (cp_cache != NULL) {
2666             cp_cache->adjust_method_entries(_matching_old_methods,
2667                                             _matching_new_methods,
2668                                             _matching_methods_length,
2669                                             &trace_name_printed);
2670           }
2671         }
2672       } // pvw is cleaned up
2673     } // rm is cleaned up
2674   }
2675 }
2676 
2677 void VM_RedefineClasses::update_jmethod_ids() {
2678   for (int j = 0; j < _matching_methods_length; ++j) {
2679     methodOop old_method = _matching_old_methods[j];
2680     jmethodID jmid = old_method->find_jmethod_id_or_null();
2681     if (jmid != NULL) {
2682       // There is a jmethodID, change it to point to the new method
2683       methodHandle new_method_h(_matching_new_methods[j]);
2684       JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
2685       assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2686              "should be replaced");
2687     }
2688   }
2689 }
2690 
2691 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2692        BitMap *emcp_methods, int * emcp_method_count_p) {
2693   *emcp_method_count_p = 0;
2694   int obsolete_count = 0;
2695   int old_index = 0;
2696   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2697     methodOop old_method = _matching_old_methods[j];
2698     methodOop new_method = _matching_new_methods[j];
2699     methodOop old_array_method;
2700 
2701     // Maintain an old_index into the _old_methods array by skipping
2702     // deleted methods
2703     while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
2704                                                             != old_method) {
2705       ++old_index;
2706     }
2707 
2708     if (MethodComparator::methods_EMCP(old_method, new_method)) {
2709       // The EMCP definition from JSR-163 requires the bytecodes to be
2710       // the same with the exception of constant pool indices which may
2711       // differ. However, the constants referred to by those indices
2712       // must be the same.
2713       //
2714       // We use methods_EMCP() for comparison since constant pool
2715       // merging can remove duplicate constant pool entries that were
2716       // present in the old method and removed from the rewritten new
2717       // method. A faster binary comparison function would consider the
2718       // old and new methods to be different when they are actually
2719       // EMCP.
2720       //
2721       // The old and new methods are EMCP and you would think that we
2722       // could get rid of one of them here and now and save some space.
2723       // However, the concept of EMCP only considers the bytecodes and
2724       // the constant pool entries in the comparison. Other things,
2725       // e.g., the line number table (LNT) or the local variable table
2726       // (LVT) don't count in the comparison. So the new (and EMCP)
2727       // method can have a new LNT that we need so we can't just
2728       // overwrite the new method with the old method.
2729       //
2730       // When this routine is called, we have already attached the new
2731       // methods to the_class so the old methods are effectively
2732       // overwritten. However, if an old method is still executing,
2733       // then the old method cannot be collected until sometime after
2734       // the old method call has returned. So the overwriting of old
2735       // methods by new methods will save us space except for those
2736       // (hopefully few) old methods that are still executing.
2737       //
2738       // A method refers to a constMethodOop and this presents another
2739       // possible avenue to space savings. The constMethodOop in the
2740       // new method contains possibly new attributes (LNT, LVT, etc).
2741       // At first glance, it seems possible to save space by replacing
2742       // the constMethodOop in the old method with the constMethodOop
2743       // from the new method. The old and new methods would share the
2744       // same constMethodOop and we would save the space occupied by
2745       // the old constMethodOop. However, the constMethodOop contains
2746       // a back reference to the containing method. Sharing the
2747       // constMethodOop between two methods could lead to confusion in
2748       // the code that uses the back reference. This would lead to
2749       // brittle code that could be broken in non-obvious ways now or
2750       // in the future.
2751       //
2752       // Another possibility is to copy the constMethodOop from the new
2753       // method to the old method and then overwrite the new method with
2754       // the old method. Since the constMethodOop contains the bytecodes
2755       // for the method embedded in the oop, this option would change
2756       // the bytecodes out from under any threads executing the old
2757       // method and make the thread's bcp invalid. Since EMCP requires
2758       // that the bytecodes be the same modulo constant pool indices, it
2759       // is straight forward to compute the correct new bcp in the new
2760       // constMethodOop from the old bcp in the old constMethodOop. The
2761       // time consuming part would be searching all the frames in all
2762       // of the threads to find all of the calls to the old method.
2763       //
2764       // It looks like we will have to live with the limited savings
2765       // that we get from effectively overwriting the old methods
2766       // when the new methods are attached to the_class.
2767 
2768       // track which methods are EMCP for add_previous_version() call
2769       emcp_methods->set_bit(old_index);
2770       (*emcp_method_count_p)++;
2771 
2772       // An EMCP method is _not_ obsolete. An obsolete method has a
2773       // different jmethodID than the current method. An EMCP method
2774       // has the same jmethodID as the current method. Having the
2775       // same jmethodID for all EMCP versions of a method allows for
2776       // a consistent view of the EMCP methods regardless of which
2777       // EMCP method you happen to have in hand. For example, a
2778       // breakpoint set in one EMCP method will work for all EMCP
2779       // versions of the method including the current one.
2780     } else {
2781       // mark obsolete methods as such
2782       old_method->set_is_obsolete();
2783       obsolete_count++;
2784 
2785       // obsolete methods need a unique idnum
2786       u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
2787       if (num != constMethodOopDesc::UNSET_IDNUM) {
2788 //      u2 old_num = old_method->method_idnum();
2789         old_method->set_method_idnum(num);
2790 // TO DO: attach obsolete annotations to obsolete method's new idnum
2791       }
2792       // With tracing we try not to "yack" too much. The position of
2793       // this trace assumes there are fewer obsolete methods than
2794       // EMCP methods.
2795       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2796         old_method->name()->as_C_string(),
2797         old_method->signature()->as_C_string()));
2798     }
2799     old_method->set_is_old();
2800   }
2801   for (int i = 0; i < _deleted_methods_length; ++i) {
2802     methodOop old_method = _deleted_methods[i];
2803 
2804     assert(old_method->vtable_index() < 0,
2805            "cannot delete methods with vtable entries");;
2806 
2807     // Mark all deleted methods as old and obsolete
2808     old_method->set_is_old();
2809     old_method->set_is_obsolete();
2810     ++obsolete_count;
2811     // With tracing we try not to "yack" too much. The position of
2812     // this trace assumes there are fewer obsolete methods than
2813     // EMCP methods.
2814     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2815                           old_method->name()->as_C_string(),
2816                           old_method->signature()->as_C_string()));
2817   }
2818   assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2819     "sanity check");
2820   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2821     obsolete_count));
2822 }
2823 
2824 // This internal class transfers the native function registration from old methods
2825 // to new methods.  It is designed to handle both the simple case of unchanged
2826 // native methods and the complex cases of native method prefixes being added and/or
2827 // removed.
2828 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2829 //
2830 // This class is used after the new methods have been installed in "the_class".
2831 //
2832 // So, for example, the following must be handled.  Where 'm' is a method and
2833 // a number followed by an underscore is a prefix.
2834 //
2835 //                                      Old Name    New Name
2836 // Simple transfer to new method        m       ->  m
2837 // Add prefix                           m       ->  1_m
2838 // Remove prefix                        1_m     ->  m
2839 // Simultaneous add of prefixes         m       ->  3_2_1_m
2840 // Simultaneous removal of prefixes     3_2_1_m ->  m
2841 // Simultaneous add and remove          1_m     ->  2_m
2842 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
2843 //
2844 class TransferNativeFunctionRegistration {
2845  private:
2846   instanceKlassHandle the_class;
2847   int prefix_count;
2848   char** prefixes;
2849 
2850   // Recursively search the binary tree of possibly prefixed method names.
2851   // Iteration could be used if all agents were well behaved. Full tree walk is
2852   // more resilent to agents not cleaning up intermediate methods.
2853   // Branch at each depth in the binary tree is:
2854   //    (1) without the prefix.
2855   //    (2) with the prefix.
2856   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2857   methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
2858                                      Symbol* signature) {
2859     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
2860     if (name_symbol != NULL) {
2861       methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
2862       if (method != NULL) {
2863         // Even if prefixed, intermediate methods must exist.
2864         if (method->is_native()) {
2865           // Wahoo, we found a (possibly prefixed) version of the method, return it.
2866           return method;
2867         }
2868         if (depth < prefix_count) {
2869           // Try applying further prefixes (other than this one).
2870           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2871           if (method != NULL) {
2872             return method; // found
2873           }
2874 
2875           // Try adding this prefix to the method name and see if it matches
2876           // another method name.
2877           char* prefix = prefixes[depth];
2878           size_t prefix_len = strlen(prefix);
2879           size_t trial_len = name_len + prefix_len;
2880           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2881           strcpy(trial_name_str, prefix);
2882           strcat(trial_name_str, name_str);
2883           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2884                                             signature);
2885           if (method != NULL) {
2886             // If found along this branch, it was prefixed, mark as such
2887             method->set_is_prefixed_native();
2888             return method; // found
2889           }
2890         }
2891       }
2892     }
2893     return NULL;  // This whole branch bore nothing
2894   }
2895 
2896   // Return the method name with old prefixes stripped away.
2897   char* method_name_without_prefixes(methodOop method) {
2898     Symbol* name = method->name();
2899     char* name_str = name->as_utf8();
2900 
2901     // Old prefixing may be defunct, strip prefixes, if any.
2902     for (int i = prefix_count-1; i >= 0; i--) {
2903       char* prefix = prefixes[i];
2904       size_t prefix_len = strlen(prefix);
2905       if (strncmp(prefix, name_str, prefix_len) == 0) {
2906         name_str += prefix_len;
2907       }
2908     }
2909     return name_str;
2910   }
2911 
2912   // Strip any prefixes off the old native method, then try to find a
2913   // (possibly prefixed) new native that matches it.
2914   methodOop strip_and_search_for_new_native(methodOop method) {
2915     ResourceMark rm;
2916     char* name_str = method_name_without_prefixes(method);
2917     return search_prefix_name_space(0, name_str, strlen(name_str),
2918                                     method->signature());
2919   }
2920 
2921  public:
2922 
2923   // Construct a native method transfer processor for this class.
2924   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2925     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2926 
2927     the_class = _the_class;
2928     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
2929   }
2930 
2931   // Attempt to transfer any of the old or deleted methods that are native
2932   void transfer_registrations(methodOop* old_methods, int methods_length) {
2933     for (int j = 0; j < methods_length; j++) {
2934       methodOop old_method = old_methods[j];
2935 
2936       if (old_method->is_native() && old_method->has_native_function()) {
2937         methodOop new_method = strip_and_search_for_new_native(old_method);
2938         if (new_method != NULL) {
2939           // Actually set the native function in the new method.
2940           // Redefine does not send events (except CFLH), certainly not this
2941           // behind the scenes re-registration.
2942           new_method->set_native_function(old_method->native_function(),
2943                               !methodOopDesc::native_bind_event_is_interesting);
2944         }
2945       }
2946     }
2947   }
2948 };
2949 
2950 // Don't lose the association between a native method and its JNI function.
2951 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
2952   TransferNativeFunctionRegistration transfer(the_class);
2953   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
2954   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
2955 }
2956 
2957 // Deoptimize all compiled code that depends on this class.
2958 //
2959 // If the can_redefine_classes capability is obtained in the onload
2960 // phase then the compiler has recorded all dependencies from startup.
2961 // In that case we need only deoptimize and throw away all compiled code
2962 // that depends on the class.
2963 //
2964 // If can_redefine_classes is obtained sometime after the onload
2965 // phase then the dependency information may be incomplete. In that case
2966 // the first call to RedefineClasses causes all compiled code to be
2967 // thrown away. As can_redefine_classes has been obtained then
2968 // all future compilations will record dependencies so second and
2969 // subsequent calls to RedefineClasses need only throw away code
2970 // that depends on the class.
2971 //
2972 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
2973   assert_locked_or_safepoint(Compile_lock);
2974 
2975   // All dependencies have been recorded from startup or this is a second or
2976   // subsequent use of RedefineClasses
2977   if (JvmtiExport::all_dependencies_are_recorded()) {
2978     Universe::flush_evol_dependents_on(k_h);
2979   } else {
2980     CodeCache::mark_all_nmethods_for_deoptimization();
2981 
2982     ResourceMark rm(THREAD);
2983     DeoptimizationMarker dm;
2984 
2985     // Deoptimize all activations depending on marked nmethods
2986     Deoptimization::deoptimize_dependents();
2987 
2988     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
2989     CodeCache::make_marked_nmethods_not_entrant();
2990 
2991     // From now on we know that the dependency information is complete
2992     JvmtiExport::set_all_dependencies_are_recorded(true);
2993   }
2994 }
2995 
2996 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
2997   methodOop old_method;
2998   methodOop new_method;
2999 
3000   _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3001   _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3002   _added_methods        = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
3003   _deleted_methods      = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3004 
3005   _matching_methods_length = 0;
3006   _deleted_methods_length  = 0;
3007   _added_methods_length    = 0;
3008 
3009   int nj = 0;
3010   int oj = 0;
3011   while (true) {
3012     if (oj >= _old_methods->length()) {
3013       if (nj >= _new_methods->length()) {
3014         break; // we've looked at everything, done
3015       }
3016       // New method at the end
3017       new_method = (methodOop) _new_methods->obj_at(nj);
3018       _added_methods[_added_methods_length++] = new_method;
3019       ++nj;
3020     } else if (nj >= _new_methods->length()) {
3021       // Old method, at the end, is deleted
3022       old_method = (methodOop) _old_methods->obj_at(oj);
3023       _deleted_methods[_deleted_methods_length++] = old_method;
3024       ++oj;
3025     } else {
3026       old_method = (methodOop) _old_methods->obj_at(oj);
3027       new_method = (methodOop) _new_methods->obj_at(nj);
3028       if (old_method->name() == new_method->name()) {
3029         if (old_method->signature() == new_method->signature()) {
3030           _matching_old_methods[_matching_methods_length  ] = old_method;
3031           _matching_new_methods[_matching_methods_length++] = new_method;
3032           ++nj;
3033           ++oj;
3034         } else {
3035           // added overloaded have already been moved to the end,
3036           // so this is a deleted overloaded method
3037           _deleted_methods[_deleted_methods_length++] = old_method;
3038           ++oj;
3039         }
3040       } else { // names don't match
3041         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3042           // new method
3043           _added_methods[_added_methods_length++] = new_method;
3044           ++nj;
3045         } else {
3046           // deleted method
3047           _deleted_methods[_deleted_methods_length++] = old_method;
3048           ++oj;
3049         }
3050       }
3051     }
3052   }
3053   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3054   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3055 }
3056 
3057 
3058 
3059 // Install the redefinition of a class:
3060 //    - house keeping (flushing breakpoints and caches, deoptimizing
3061 //      dependent compiled code)
3062 //    - replacing parts in the_class with parts from scratch_class
3063 //    - adding a weak reference to track the obsolete but interesting
3064 //      parts of the_class
3065 //    - adjusting constant pool caches and vtables in other classes
3066 //      that refer to methods in the_class. These adjustments use the
3067 //      SystemDictionary::classes_do() facility which only allows
3068 //      a helper method to be specified. The interesting parameters
3069 //      that we would like to pass to the helper method are saved in
3070 //      static global fields in the VM operation.
3071 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3072        instanceKlassHandle scratch_class, TRAPS) {
3073 
3074   RC_TIMER_START(_timer_rsc_phase1);
3075 
3076   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3077   klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
3078   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3079 
3080 #ifndef JVMTI_KERNEL
3081   // Remove all breakpoints in methods of this class
3082   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3083   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3084 #endif // !JVMTI_KERNEL
3085 
3086   if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3087     // We are redefining java.lang.reflect.Method. Method.invoke() is
3088     // cached and users of the cache care about each active version of
3089     // the method so we have to track this previous version.
3090     // Do this before methods get switched
3091     Universe::reflect_invoke_cache()->add_previous_version(
3092       the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3093   }
3094 
3095   // Deoptimize all compiled code that depends on this class
3096   flush_dependent_code(the_class, THREAD);
3097 
3098   _old_methods = the_class->methods();
3099   _new_methods = scratch_class->methods();
3100   _the_class_oop = the_class_oop;
3101   compute_added_deleted_matching_methods();
3102   update_jmethod_ids();
3103 
3104   // Attach new constant pool to the original klass. The original
3105   // klass still refers to the old constant pool (for now).
3106   scratch_class->constants()->set_pool_holder(the_class());
3107 
3108 #if 0
3109   // In theory, with constant pool merging in place we should be able
3110   // to save space by using the new, merged constant pool in place of
3111   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3112   // the klass version we are replacing now and any constant pool(s) in
3113   // previous versions of klass. Nice theory, doesn't work in practice.
3114   // When this code is enabled, even simple programs throw NullPointer
3115   // exceptions. I'm guessing that this is caused by some constant pool
3116   // cache difference between the new, merged constant pool and the
3117   // constant pool that was just being used by the klass. I'm keeping
3118   // this code around to archive the idea, but the code has to remain
3119   // disabled for now.
3120 
3121   // Attach each old method to the new constant pool. This can be
3122   // done here since we are past the bytecode verification and
3123   // constant pool optimization phases.
3124   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3125     methodOop method = (methodOop)_old_methods->obj_at(i);
3126     method->set_constants(scratch_class->constants());
3127   }
3128 
3129   {
3130     // walk all previous versions of the klass
3131     instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
3132     PreviousVersionWalker pvw(ik);
3133     instanceKlassHandle ikh;
3134     do {
3135       ikh = pvw.next_previous_version();
3136       if (!ikh.is_null()) {
3137         ik = ikh();
3138 
3139         // attach previous version of klass to the new constant pool
3140         ik->set_constants(scratch_class->constants());
3141 
3142         // Attach each method in the previous version of klass to the
3143         // new constant pool
3144         objArrayOop prev_methods = ik->methods();
3145         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3146           methodOop method = (methodOop)prev_methods->obj_at(i);
3147           method->set_constants(scratch_class->constants());
3148         }
3149       }
3150     } while (!ikh.is_null());
3151   }
3152 #endif
3153 
3154   // Replace methods and constantpool
3155   the_class->set_methods(_new_methods);
3156   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3157                                           // and to be able to undo operation easily.
3158 
3159   constantPoolOop old_constants = the_class->constants();
3160   the_class->set_constants(scratch_class->constants());
3161   scratch_class->set_constants(old_constants);  // See the previous comment.
3162 #if 0
3163   // We are swapping the guts of "the new class" with the guts of "the
3164   // class". Since the old constant pool has just been attached to "the
3165   // new class", it seems logical to set the pool holder in the old
3166   // constant pool also. However, doing this will change the observable
3167   // class hierarchy for any old methods that are still executing. A
3168   // method can query the identity of its "holder" and this query uses
3169   // the method's constant pool link to find the holder. The change in
3170   // holding class from "the class" to "the new class" can confuse
3171   // things.
3172   //
3173   // Setting the old constant pool's holder will also cause
3174   // verification done during vtable initialization below to fail.
3175   // During vtable initialization, the vtable's class is verified to be
3176   // a subtype of the method's holder. The vtable's class is "the
3177   // class" and the method's holder is gotten from the constant pool
3178   // link in the method itself. For "the class"'s directly implemented
3179   // methods, the method holder is "the class" itself (as gotten from
3180   // the new constant pool). The check works fine in this case. The
3181   // check also works fine for methods inherited from super classes.
3182   //
3183   // Miranda methods are a little more complicated. A miranda method is
3184   // provided by an interface when the class implementing the interface
3185   // does not provide its own method.  These interfaces are implemented
3186   // internally as an instanceKlass. These special instanceKlasses
3187   // share the constant pool of the class that "implements" the
3188   // interface. By sharing the constant pool, the method holder of a
3189   // miranda method is the class that "implements" the interface. In a
3190   // non-redefine situation, the subtype check works fine. However, if
3191   // the old constant pool's pool holder is modified, then the check
3192   // fails because there is no class hierarchy relationship between the
3193   // vtable's class and "the new class".
3194 
3195   old_constants->set_pool_holder(scratch_class());
3196 #endif
3197 
3198   // track which methods are EMCP for add_previous_version() call below
3199   BitMap emcp_methods(_old_methods->length());
3200   int emcp_method_count = 0;
3201   emcp_methods.clear();  // clears 0..(length() - 1)
3202   check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3203   transfer_old_native_function_registrations(the_class);
3204 
3205   // The class file bytes from before any retransformable agents mucked
3206   // with them was cached on the scratch class, move to the_class.
3207   // Note: we still want to do this if nothing needed caching since it
3208   // should get cleared in the_class too.
3209   if (the_class->get_cached_class_file_bytes() == 0) {
3210     // the_class doesn't have a cache yet so copy it
3211     the_class->set_cached_class_file(
3212       scratch_class->get_cached_class_file_bytes(),
3213       scratch_class->get_cached_class_file_len());
3214   }
3215 #ifndef PRODUCT
3216   else {
3217     assert(the_class->get_cached_class_file_bytes() ==
3218       scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
3219     assert(the_class->get_cached_class_file_len() ==
3220       scratch_class->get_cached_class_file_len(), "cache lens must match");
3221   }
3222 #endif
3223 
3224   // Replace inner_classes
3225   typeArrayOop old_inner_classes = the_class->inner_classes();
3226   the_class->set_inner_classes(scratch_class->inner_classes());
3227   scratch_class->set_inner_classes(old_inner_classes);
3228 
3229   // Initialize the vtable and interface table after
3230   // methods have been rewritten
3231   {
3232     ResourceMark rm(THREAD);
3233     // no exception should happen here since we explicitly
3234     // do not check loader constraints.
3235     // compare_and_normalize_class_versions has already checked:
3236     //  - classloaders unchanged, signatures unchanged
3237     //  - all instanceKlasses for redefined classes reused & contents updated
3238     the_class->vtable()->initialize_vtable(false, THREAD);
3239     the_class->itable()->initialize_itable(false, THREAD);
3240     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3241   }
3242 
3243   // Leave arrays of jmethodIDs and itable index cache unchanged
3244 
3245   // Copy the "source file name" attribute from new class version
3246   the_class->set_source_file_name(scratch_class->source_file_name());
3247 
3248   // Copy the "source debug extension" attribute from new class version
3249   the_class->set_source_debug_extension(
3250     scratch_class->source_debug_extension(),
3251     scratch_class->source_debug_extension() == NULL ? 0 :
3252     (int)strlen(scratch_class->source_debug_extension()));
3253 
3254   // Use of javac -g could be different in the old and the new
3255   if (scratch_class->access_flags().has_localvariable_table() !=
3256       the_class->access_flags().has_localvariable_table()) {
3257 
3258     AccessFlags flags = the_class->access_flags();
3259     if (scratch_class->access_flags().has_localvariable_table()) {
3260       flags.set_has_localvariable_table();
3261     } else {
3262       flags.clear_has_localvariable_table();
3263     }
3264     the_class->set_access_flags(flags);
3265   }
3266 
3267   // Replace class annotation fields values
3268   typeArrayOop old_class_annotations = the_class->class_annotations();
3269   the_class->set_class_annotations(scratch_class->class_annotations());
3270   scratch_class->set_class_annotations(old_class_annotations);
3271 
3272   // Replace fields annotation fields values
3273   objArrayOop old_fields_annotations = the_class->fields_annotations();
3274   the_class->set_fields_annotations(scratch_class->fields_annotations());
3275   scratch_class->set_fields_annotations(old_fields_annotations);
3276 
3277   // Replace methods annotation fields values
3278   objArrayOop old_methods_annotations = the_class->methods_annotations();
3279   the_class->set_methods_annotations(scratch_class->methods_annotations());
3280   scratch_class->set_methods_annotations(old_methods_annotations);
3281 
3282   // Replace methods parameter annotation fields values
3283   objArrayOop old_methods_parameter_annotations =
3284     the_class->methods_parameter_annotations();
3285   the_class->set_methods_parameter_annotations(
3286     scratch_class->methods_parameter_annotations());
3287   scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
3288 
3289   // Replace methods default annotation fields values
3290   objArrayOop old_methods_default_annotations =
3291     the_class->methods_default_annotations();
3292   the_class->set_methods_default_annotations(
3293     scratch_class->methods_default_annotations());
3294   scratch_class->set_methods_default_annotations(old_methods_default_annotations);
3295 
3296   // Replace minor version number of class file
3297   u2 old_minor_version = the_class->minor_version();
3298   the_class->set_minor_version(scratch_class->minor_version());
3299   scratch_class->set_minor_version(old_minor_version);
3300 
3301   // Replace major version number of class file
3302   u2 old_major_version = the_class->major_version();
3303   the_class->set_major_version(scratch_class->major_version());
3304   scratch_class->set_major_version(old_major_version);
3305 
3306   // Replace CP indexes for class and name+type of enclosing method
3307   u2 old_class_idx  = the_class->enclosing_method_class_index();
3308   u2 old_method_idx = the_class->enclosing_method_method_index();
3309   the_class->set_enclosing_method_indices(
3310     scratch_class->enclosing_method_class_index(),
3311     scratch_class->enclosing_method_method_index());
3312   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3313 
3314   // keep track of previous versions of this class
3315   the_class->add_previous_version(scratch_class, &emcp_methods,
3316     emcp_method_count);
3317 
3318   RC_TIMER_STOP(_timer_rsc_phase1);
3319   RC_TIMER_START(_timer_rsc_phase2);
3320 
3321   // Adjust constantpool caches and vtables for all classes
3322   // that reference methods of the evolved class.
3323   SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3324 
3325   if (the_class->oop_map_cache() != NULL) {
3326     // Flush references to any obsolete methods from the oop map cache
3327     // so that obsolete methods are not pinned.
3328     the_class->oop_map_cache()->flush_obsolete_entries();
3329   }
3330 
3331   // increment the classRedefinedCount field in the_class and in any
3332   // direct and indirect subclasses of the_class
3333   increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
3334 
3335   // RC_TRACE macro has an embedded ResourceMark
3336   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3337     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3338     the_class->external_name(),
3339     java_lang_Class::classRedefinedCount(the_class_mirror),
3340     os::available_memory() >> 10));
3341 
3342   RC_TIMER_STOP(_timer_rsc_phase2);
3343 } // end redefine_single_class()
3344 
3345 
3346 // Increment the classRedefinedCount field in the specific instanceKlass
3347 // and in all direct and indirect subclasses.
3348 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
3349   oop class_mirror = ik->java_mirror();
3350   klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
3351   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3352   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3353 
3354   if (class_oop != _the_class_oop) {
3355     // _the_class_oop count is printed at end of redefine_single_class()
3356     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3357       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3358   }
3359 
3360   for (Klass *subk = ik->subklass(); subk != NULL;
3361        subk = subk->next_sibling()) {
3362     if (subk->oop_is_instance()) {
3363       // Only update instanceKlasses
3364       instanceKlass *subik = (instanceKlass*)subk;
3365       // recursively do subclasses of the current subclass
3366       increment_class_counter(subik, THREAD);
3367     }
3368   }
3369 }
3370 
3371 #ifndef PRODUCT
3372 void VM_RedefineClasses::check_class(klassOop k_oop,
3373        oop initiating_loader, TRAPS) {
3374   Klass *k = k_oop->klass_part();
3375   if (k->oop_is_instance()) {
3376     HandleMark hm(THREAD);
3377     instanceKlass *ik = (instanceKlass *) k;
3378 
3379     if (ik->vtable_length() > 0) {
3380       ResourceMark rm(THREAD);
3381       if (!ik->vtable()->check_no_old_entries()) {
3382         tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());







3383         ik->vtable()->dump_vtable();

































3384         dump_methods();
3385         assert(false, "OLD method found");


3386       }

3387     }
3388   }
3389 }
3390 
3391 void VM_RedefineClasses::dump_methods() {
3392         int j;
3393         tty->print_cr("_old_methods --");
3394         for (j = 0; j < _old_methods->length(); ++j) {
3395           methodOop m = (methodOop) _old_methods->obj_at(j);
3396           tty->print("%4d  (%5d)  ", j, m->vtable_index());
3397           m->access_flags().print_on(tty);
3398           tty->print(" --  ");
3399           m->print_name(tty);
3400           tty->cr();
3401         }
3402         tty->print_cr("_new_methods --");
3403         for (j = 0; j < _new_methods->length(); ++j) {
3404           methodOop m = (methodOop) _new_methods->obj_at(j);
3405           tty->print("%4d  (%5d)  ", j, m->vtable_index());
3406           m->access_flags().print_on(tty);
3407           tty->print(" --  ");
3408           m->print_name(tty);
3409           tty->cr();
3410         }
3411         tty->print_cr("_matching_(old/new)_methods --");
3412         for (j = 0; j < _matching_methods_length; ++j) {
3413           methodOop m = _matching_old_methods[j];
3414           tty->print("%4d  (%5d)  ", j, m->vtable_index());
3415           m->access_flags().print_on(tty);
3416           tty->print(" --  ");
3417           m->print_name(tty);
3418           tty->cr();
3419           m = _matching_new_methods[j];
3420           tty->print("      (%5d)  ", m->vtable_index());
3421           m->access_flags().print_on(tty);
3422           tty->cr();
3423         }
3424         tty->print_cr("_deleted_methods --");
3425         for (j = 0; j < _deleted_methods_length; ++j) {
3426           methodOop m = _deleted_methods[j];
3427           tty->print("%4d  (%5d)  ", j, m->vtable_index());
3428           m->access_flags().print_on(tty);
3429           tty->print(" --  ");
3430           m->print_name(tty);
3431           tty->cr();
3432         }
3433         tty->print_cr("_added_methods --");
3434         for (j = 0; j < _added_methods_length; ++j) {
3435           methodOop m = _added_methods[j];
3436           tty->print("%4d  (%5d)  ", j, m->vtable_index());
3437           m->access_flags().print_on(tty);
3438           tty->print(" --  ");
3439           m->print_name(tty);
3440           tty->cr();
3441         }
3442 }
3443 #endif
--- EOF ---