1 /*
   2  * Copyright (c) 2003, 2013, 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 // check_class() is optionally called for product bits, but is
 133 // always called for non-product bits.
 134 #ifdef PRODUCT
 135   if (RC_TRACE_ENABLED(0x00004000)) {
 136 #endif
 137     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
 138     SystemDictionary::classes_do(check_class, thread);
 139 #ifdef PRODUCT
 140   }
 141 #endif
 142 }
 143 
 144 void VM_RedefineClasses::doit_epilogue() {
 145   // Free os::malloc allocated memory.
 146   // The memory allocated in redefine will be free'ed in next VM operation.
 147   os::free(_scratch_classes);
 148 
 149   if (RC_TRACE_ENABLED(0x00000004)) {
 150     // Used to have separate timers for "doit" and "all", but the timer
 151     // overhead skewed the measurements.
 152     jlong doit_time = _timer_rsc_phase1.milliseconds() +
 153                       _timer_rsc_phase2.milliseconds();
 154     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 155 
 156     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
 157       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
 158       _timer_vm_op_prologue.milliseconds(), doit_time));
 159     RC_TRACE(0x00000004,
 160       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
 161        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
 162   }
 163 }
 164 
 165 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 166   // classes for primitives cannot be redefined
 167   if (java_lang_Class::is_primitive(klass_mirror)) {
 168     return false;
 169   }
 170   klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
 171   // classes for arrays cannot be redefined
 172   if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
 173     return false;
 174   }
 175   return true;
 176 }
 177 
 178 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 179 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 180 // direct CP entries, there is just the current entry to append. For
 181 // indirect and double-indirect CP entries, there are zero or more
 182 // referenced CP entries along with the current entry to append.
 183 // Indirect and double-indirect CP entries are handled by recursive
 184 // calls to append_entry() as needed. The referenced CP entries are
 185 // always appended to *merge_cp_p before the referee CP entry. These
 186 // referenced CP entries may already exist in *merge_cp_p in which case
 187 // there is nothing extra to append and only the current entry is
 188 // appended.
 189 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
 190        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 191        TRAPS) {
 192 
 193   // append is different depending on entry tag type
 194   switch (scratch_cp->tag_at(scratch_i).value()) {
 195 
 196     // The old verifier is implemented outside the VM. It loads classes,
 197     // but does not resolve constant pool entries directly so we never
 198     // see Class entries here with the old verifier. Similarly the old
 199     // verifier does not like Class entries in the input constant pool.
 200     // The split-verifier is implemented in the VM so it can optionally
 201     // and directly resolve constant pool entries to load classes. The
 202     // split-verifier can accept either Class entries or UnresolvedClass
 203     // entries in the input constant pool. We revert the appended copy
 204     // back to UnresolvedClass so that either verifier will be happy
 205     // with the constant pool entry.
 206     case JVM_CONSTANT_Class:
 207     {
 208       // revert the copy to JVM_CONSTANT_UnresolvedClass
 209       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
 210         scratch_cp->klass_name_at(scratch_i));
 211 
 212       if (scratch_i != *merge_cp_length_p) {
 213         // The new entry in *merge_cp_p is at a different index than
 214         // the new entry in scratch_cp so we need to map the index values.
 215         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 216       }
 217       (*merge_cp_length_p)++;
 218     } break;
 219 
 220     // these are direct CP entries so they can be directly appended,
 221     // but double and long take two constant pool entries
 222     case JVM_CONSTANT_Double:  // fall through
 223     case JVM_CONSTANT_Long:
 224     {
 225       constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 226         THREAD);
 227 
 228       if (scratch_i != *merge_cp_length_p) {
 229         // The new entry in *merge_cp_p is at a different index than
 230         // the new entry in scratch_cp so we need to map the index values.
 231         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 232       }
 233       (*merge_cp_length_p) += 2;
 234     } break;
 235 
 236     // these are direct CP entries so they can be directly appended
 237     case JVM_CONSTANT_Float:   // fall through
 238     case JVM_CONSTANT_Integer: // fall through
 239     case JVM_CONSTANT_Utf8:    // fall through
 240 
 241     // This was an indirect CP entry, but it has been changed into
 242     // an interned string so this entry can be directly appended.
 243     case JVM_CONSTANT_String:      // fall through
 244 
 245     // These were indirect CP entries, but they have been changed into
 246     // Symbol*s so these entries can be directly appended.
 247     case JVM_CONSTANT_UnresolvedClass:  // fall through
 248     case JVM_CONSTANT_UnresolvedString:
 249     {
 250       constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 251         THREAD);
 252 
 253       if (scratch_i != *merge_cp_length_p) {
 254         // The new entry in *merge_cp_p is at a different index than
 255         // the new entry in scratch_cp so we need to map the index values.
 256         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 257       }
 258       (*merge_cp_length_p)++;
 259     } break;
 260 
 261     // this is an indirect CP entry so it needs special handling
 262     case JVM_CONSTANT_NameAndType:
 263     {
 264       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 265       int new_name_ref_i = 0;
 266       bool match = (name_ref_i < *merge_cp_length_p) &&
 267         scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
 268           THREAD);
 269       if (!match) {
 270         // forward reference in *merge_cp_p or not a direct match
 271 
 272         int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
 273           THREAD);
 274         if (found_i != 0) {
 275           guarantee(found_i != name_ref_i,
 276             "compare_entry_to() and find_matching_entry() do not agree");
 277 
 278           // Found a matching entry somewhere else in *merge_cp_p so
 279           // just need a mapping entry.
 280           new_name_ref_i = found_i;
 281           map_index(scratch_cp, name_ref_i, found_i);
 282         } else {
 283           // no match found so we have to append this entry to *merge_cp_p
 284           append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
 285             THREAD);
 286           // The above call to append_entry() can only append one entry
 287           // so the post call query of *merge_cp_length_p is only for
 288           // the sake of consistency.
 289           new_name_ref_i = *merge_cp_length_p - 1;
 290         }
 291       }
 292 
 293       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 294       int new_signature_ref_i = 0;
 295       match = (signature_ref_i < *merge_cp_length_p) &&
 296         scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
 297           signature_ref_i, THREAD);
 298       if (!match) {
 299         // forward reference in *merge_cp_p or not a direct match
 300 
 301         int found_i = scratch_cp->find_matching_entry(signature_ref_i,
 302           *merge_cp_p, THREAD);
 303         if (found_i != 0) {
 304           guarantee(found_i != signature_ref_i,
 305             "compare_entry_to() and find_matching_entry() do not agree");
 306 
 307           // Found a matching entry somewhere else in *merge_cp_p so
 308           // just need a mapping entry.
 309           new_signature_ref_i = found_i;
 310           map_index(scratch_cp, signature_ref_i, found_i);
 311         } else {
 312           // no match found so we have to append this entry to *merge_cp_p
 313           append_entry(scratch_cp, signature_ref_i, merge_cp_p,
 314             merge_cp_length_p, THREAD);
 315           // The above call to append_entry() can only append one entry
 316           // so the post call query of *merge_cp_length_p is only for
 317           // the sake of consistency.
 318           new_signature_ref_i = *merge_cp_length_p - 1;
 319         }
 320       }
 321 
 322       // If the referenced entries already exist in *merge_cp_p, then
 323       // both new_name_ref_i and new_signature_ref_i will both be 0.
 324       // In that case, all we are appending is the current entry.
 325       if (new_name_ref_i == 0) {
 326         new_name_ref_i = name_ref_i;
 327       } else {
 328         RC_TRACE(0x00080000,
 329           ("NameAndType entry@%d name_ref_index change: %d to %d",
 330           *merge_cp_length_p, name_ref_i, new_name_ref_i));
 331       }
 332       if (new_signature_ref_i == 0) {
 333         new_signature_ref_i = signature_ref_i;
 334       } else {
 335         RC_TRACE(0x00080000,
 336           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 337           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
 338       }
 339 
 340       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 341         new_name_ref_i, new_signature_ref_i);
 342       if (scratch_i != *merge_cp_length_p) {
 343         // The new entry in *merge_cp_p is at a different index than
 344         // the new entry in scratch_cp so we need to map the index values.
 345         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 346       }
 347       (*merge_cp_length_p)++;
 348     } break;
 349 
 350     // this is a double-indirect CP entry so it needs special handling
 351     case JVM_CONSTANT_Fieldref:           // fall through
 352     case JVM_CONSTANT_InterfaceMethodref: // fall through
 353     case JVM_CONSTANT_Methodref:
 354     {
 355       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 356       int new_klass_ref_i = 0;
 357       bool match = (klass_ref_i < *merge_cp_length_p) &&
 358         scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
 359           THREAD);
 360       if (!match) {
 361         // forward reference in *merge_cp_p or not a direct match
 362 
 363         int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
 364           THREAD);
 365         if (found_i != 0) {
 366           guarantee(found_i != klass_ref_i,
 367             "compare_entry_to() and find_matching_entry() do not agree");
 368 
 369           // Found a matching entry somewhere else in *merge_cp_p so
 370           // just need a mapping entry.
 371           new_klass_ref_i = found_i;
 372           map_index(scratch_cp, klass_ref_i, found_i);
 373         } else {
 374           // no match found so we have to append this entry to *merge_cp_p
 375           append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
 376             THREAD);
 377           // The above call to append_entry() can only append one entry
 378           // so the post call query of *merge_cp_length_p is only for
 379           // the sake of consistency. Without the optimization where we
 380           // use JVM_CONSTANT_UnresolvedClass, then up to two entries
 381           // could be appended.
 382           new_klass_ref_i = *merge_cp_length_p - 1;
 383         }
 384       }
 385 
 386       int name_and_type_ref_i =
 387         scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 388       int new_name_and_type_ref_i = 0;
 389       match = (name_and_type_ref_i < *merge_cp_length_p) &&
 390         scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
 391           name_and_type_ref_i, THREAD);
 392       if (!match) {
 393         // forward reference in *merge_cp_p or not a direct match
 394 
 395         int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
 396           *merge_cp_p, THREAD);
 397         if (found_i != 0) {
 398           guarantee(found_i != name_and_type_ref_i,
 399             "compare_entry_to() and find_matching_entry() do not agree");
 400 
 401           // Found a matching entry somewhere else in *merge_cp_p so
 402           // just need a mapping entry.
 403           new_name_and_type_ref_i = found_i;
 404           map_index(scratch_cp, name_and_type_ref_i, found_i);
 405         } else {
 406           // no match found so we have to append this entry to *merge_cp_p
 407           append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
 408             merge_cp_length_p, THREAD);
 409           // The above call to append_entry() can append more than
 410           // one entry so the post call query of *merge_cp_length_p
 411           // is required in order to get the right index for the
 412           // JVM_CONSTANT_NameAndType entry.
 413           new_name_and_type_ref_i = *merge_cp_length_p - 1;
 414         }
 415       }
 416 
 417       // If the referenced entries already exist in *merge_cp_p, then
 418       // both new_klass_ref_i and new_name_and_type_ref_i will both be
 419       // 0. In that case, all we are appending is the current entry.
 420       if (new_klass_ref_i == 0) {
 421         new_klass_ref_i = klass_ref_i;
 422       }
 423       if (new_name_and_type_ref_i == 0) {
 424         new_name_and_type_ref_i = name_and_type_ref_i;
 425       }
 426 
 427       const char *entry_name;
 428       switch (scratch_cp->tag_at(scratch_i).value()) {
 429       case JVM_CONSTANT_Fieldref:
 430         entry_name = "Fieldref";
 431         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 432           new_name_and_type_ref_i);
 433         break;
 434       case JVM_CONSTANT_InterfaceMethodref:
 435         entry_name = "IFMethodref";
 436         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 437           new_klass_ref_i, new_name_and_type_ref_i);
 438         break;
 439       case JVM_CONSTANT_Methodref:
 440         entry_name = "Methodref";
 441         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 442           new_name_and_type_ref_i);
 443         break;
 444       default:
 445         guarantee(false, "bad switch");
 446         break;
 447       }
 448 
 449       if (klass_ref_i != new_klass_ref_i) {
 450         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
 451           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
 452       }
 453       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 454         RC_TRACE(0x00080000,
 455           ("%s entry@%d name_and_type_index changed: %d to %d",
 456           entry_name, *merge_cp_length_p, name_and_type_ref_i,
 457           new_name_and_type_ref_i));
 458       }
 459 
 460       if (scratch_i != *merge_cp_length_p) {
 461         // The new entry in *merge_cp_p is at a different index than
 462         // the new entry in scratch_cp so we need to map the index values.
 463         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 464       }
 465       (*merge_cp_length_p)++;
 466     } break;
 467 
 468     // At this stage, Class or UnresolvedClass could be here, but not
 469     // ClassIndex
 470     case JVM_CONSTANT_ClassIndex: // fall through
 471 
 472     // Invalid is used as the tag for the second constant pool entry
 473     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 474     // not be seen by itself.
 475     case JVM_CONSTANT_Invalid: // fall through
 476 
 477     // At this stage, String or UnresolvedString could be here, but not
 478     // StringIndex
 479     case JVM_CONSTANT_StringIndex: // fall through
 480 
 481     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 482     // here
 483     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 484 
 485     default:
 486     {
 487       // leave a breadcrumb
 488       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 489       ShouldNotReachHere();
 490     } break;
 491   } // end switch tag value
 492 } // end append_entry()
 493 
 494 
 495 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {
 496   typeArrayOop save;
 497 
 498   save = scratch_class->get_method_annotations_of(i);
 499   scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));
 500   scratch_class->set_method_annotations_of(j, save);
 501 
 502   save = scratch_class->get_method_parameter_annotations_of(i);
 503   scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));
 504   scratch_class->set_method_parameter_annotations_of(j, save);
 505 
 506   save = scratch_class->get_method_default_annotations_of(i);
 507   scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));
 508   scratch_class->set_method_default_annotations_of(j, save);
 509 }
 510 
 511 
 512 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 513              instanceKlassHandle the_class,
 514              instanceKlassHandle scratch_class) {
 515   int i;
 516 
 517   // Check superclasses, or rather their names, since superclasses themselves can be
 518   // requested to replace.
 519   // Check for NULL superclass first since this might be java.lang.Object
 520   if (the_class->super() != scratch_class->super() &&
 521       (the_class->super() == NULL || scratch_class->super() == NULL ||
 522        Klass::cast(the_class->super())->name() !=
 523        Klass::cast(scratch_class->super())->name())) {
 524     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 525   }
 526 
 527   // Check if the number, names and order of directly implemented interfaces are the same.
 528   // I think in principle we should just check if the sets of names of directly implemented
 529   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 530   // .java file, also changes in .class file) should not matter. However, comparing sets is
 531   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 532   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 533   // rely on it somewhere.
 534   objArrayOop k_interfaces = the_class->local_interfaces();
 535   objArrayOop k_new_interfaces = scratch_class->local_interfaces();
 536   int n_intfs = k_interfaces->length();
 537   if (n_intfs != k_new_interfaces->length()) {
 538     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 539   }
 540   for (i = 0; i < n_intfs; i++) {
 541     if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=
 542         Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
 543       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 544     }
 545   }
 546 
 547   // Check whether class is in the error init state.
 548   if (the_class->is_in_error_state()) {
 549     // TBD #5057930: special error code is needed in 1.6
 550     return JVMTI_ERROR_INVALID_CLASS;
 551   }
 552 
 553   // Check whether class modifiers are the same.
 554   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 555   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 556   if (old_flags != new_flags) {
 557     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 558   }
 559 
 560   // Check if the number, names, types and order of fields declared in these classes
 561   // are the same.
 562   JavaFieldStream old_fs(the_class);
 563   JavaFieldStream new_fs(scratch_class);
 564   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 565     // access
 566     old_flags = old_fs.access_flags().as_short();
 567     new_flags = new_fs.access_flags().as_short();
 568     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 569       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 570     }
 571     // offset
 572     if (old_fs.offset() != new_fs.offset()) {
 573       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 574     }
 575     // name and signature
 576     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 577     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 578     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 579     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 580     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 581       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 582     }
 583   }
 584 
 585   // If both streams aren't done then we have a differing number of
 586   // fields.
 587   if (!old_fs.done() || !new_fs.done()) {
 588     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 589   }
 590 
 591   // Do a parallel walk through the old and new methods. Detect
 592   // cases where they match (exist in both), have been added in
 593   // the new methods, or have been deleted (exist only in the
 594   // old methods).  The class file parser places methods in order
 595   // by method name, but does not order overloaded methods by
 596   // signature.  In order to determine what fate befell the methods,
 597   // this code places the overloaded new methods that have matching
 598   // old methods in the same order as the old methods and places
 599   // new overloaded methods at the end of overloaded methods of
 600   // that name. The code for this order normalization is adapted
 601   // from the algorithm used in instanceKlass::find_method().
 602   // Since we are swapping out of order entries as we find them,
 603   // we only have to search forward through the overloaded methods.
 604   // Methods which are added and have the same name as an existing
 605   // method (but different signature) will be put at the end of
 606   // the methods with that name, and the name mismatch code will
 607   // handle them.
 608   objArrayHandle k_old_methods(the_class->methods());
 609   objArrayHandle k_new_methods(scratch_class->methods());
 610   int n_old_methods = k_old_methods->length();
 611   int n_new_methods = k_new_methods->length();
 612 
 613   int ni = 0;
 614   int oi = 0;
 615   while (true) {
 616     methodOop k_old_method;
 617     methodOop k_new_method;
 618     enum { matched, added, deleted, undetermined } method_was = undetermined;
 619 
 620     if (oi >= n_old_methods) {
 621       if (ni >= n_new_methods) {
 622         break; // we've looked at everything, done
 623       }
 624       // New method at the end
 625       k_new_method = (methodOop) k_new_methods->obj_at(ni);
 626       method_was = added;
 627     } else if (ni >= n_new_methods) {
 628       // Old method, at the end, is deleted
 629       k_old_method = (methodOop) k_old_methods->obj_at(oi);
 630       method_was = deleted;
 631     } else {
 632       // There are more methods in both the old and new lists
 633       k_old_method = (methodOop) k_old_methods->obj_at(oi);
 634       k_new_method = (methodOop) k_new_methods->obj_at(ni);
 635       if (k_old_method->name() != k_new_method->name()) {
 636         // Methods are sorted by method name, so a mismatch means added
 637         // or deleted
 638         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 639           method_was = added;
 640         } else {
 641           method_was = deleted;
 642         }
 643       } else if (k_old_method->signature() == k_new_method->signature()) {
 644         // Both the name and signature match
 645         method_was = matched;
 646       } else {
 647         // The name matches, but the signature doesn't, which means we have to
 648         // search forward through the new overloaded methods.
 649         int nj;  // outside the loop for post-loop check
 650         for (nj = ni + 1; nj < n_new_methods; nj++) {
 651           methodOop m = (methodOop)k_new_methods->obj_at(nj);
 652           if (k_old_method->name() != m->name()) {
 653             // reached another method name so no more overloaded methods
 654             method_was = deleted;
 655             break;
 656           }
 657           if (k_old_method->signature() == m->signature()) {
 658             // found a match so swap the methods
 659             k_new_methods->obj_at_put(ni, m);
 660             k_new_methods->obj_at_put(nj, k_new_method);
 661             k_new_method = m;
 662             method_was = matched;
 663             break;
 664           }
 665         }
 666 
 667         if (nj >= n_new_methods) {
 668           // reached the end without a match; so method was deleted
 669           method_was = deleted;
 670         }
 671       }
 672     }
 673 
 674     switch (method_was) {
 675     case matched:
 676       // methods match, be sure modifiers do too
 677       old_flags = (jushort) k_old_method->access_flags().get_flags();
 678       new_flags = (jushort) k_new_method->access_flags().get_flags();
 679       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 680         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 681       }
 682       {
 683         u2 new_num = k_new_method->method_idnum();
 684         u2 old_num = k_old_method->method_idnum();
 685         if (new_num != old_num) {
 686           methodOop idnum_owner = scratch_class->method_with_idnum(old_num);
 687           if (idnum_owner != NULL) {
 688             // There is already a method assigned this idnum -- switch them
 689             idnum_owner->set_method_idnum(new_num);
 690           }
 691           k_new_method->set_method_idnum(old_num);
 692           swap_all_method_annotations(old_num, new_num, scratch_class);
 693         }
 694       }
 695       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
 696                             k_new_method->name_and_sig_as_C_string(), ni,
 697                             k_old_method->name_and_sig_as_C_string(), oi));
 698       // advance to next pair of methods
 699       ++oi;
 700       ++ni;
 701       break;
 702     case added:
 703       // method added, see if it is OK
 704       new_flags = (jushort) k_new_method->access_flags().get_flags();
 705       if ((new_flags & JVM_ACC_PRIVATE) == 0
 706            // hack: private should be treated as final, but alas
 707           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 708          ) {
 709         // new methods must be private
 710         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 711       }
 712       {
 713         u2 num = the_class->next_method_idnum();
 714         if (num == constMethodOopDesc::UNSET_IDNUM) {
 715           // cannot add any more methods
 716           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 717         }
 718         u2 new_num = k_new_method->method_idnum();
 719         methodOop idnum_owner = scratch_class->method_with_idnum(num);
 720         if (idnum_owner != NULL) {
 721           // There is already a method assigned this idnum -- switch them
 722           idnum_owner->set_method_idnum(new_num);
 723         }
 724         k_new_method->set_method_idnum(num);
 725         swap_all_method_annotations(new_num, num, scratch_class);
 726       }
 727       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
 728                             k_new_method->name_and_sig_as_C_string(), ni));
 729       ++ni; // advance to next new method
 730       break;
 731     case deleted:
 732       // method deleted, see if it is OK
 733       old_flags = (jushort) k_old_method->access_flags().get_flags();
 734       if ((old_flags & JVM_ACC_PRIVATE) == 0
 735            // hack: private should be treated as final, but alas
 736           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 737          ) {
 738         // deleted methods must be private
 739         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 740       }
 741       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
 742                             k_old_method->name_and_sig_as_C_string(), oi));
 743       ++oi; // advance to next old method
 744       break;
 745     default:
 746       ShouldNotReachHere();
 747     }
 748   }
 749 
 750   return JVMTI_ERROR_NONE;
 751 }
 752 
 753 
 754 // Find new constant pool index value for old constant pool index value
 755 // by seaching the index map. Returns zero (0) if there is no mapped
 756 // value for the old constant pool index.
 757 int VM_RedefineClasses::find_new_index(int old_index) {
 758   if (_index_map_count == 0) {
 759     // map is empty so nothing can be found
 760     return 0;
 761   }
 762 
 763   if (old_index < 1 || old_index >= _index_map_p->length()) {
 764     // The old_index is out of range so it is not mapped. This should
 765     // not happen in regular constant pool merging use, but it can
 766     // happen if a corrupt annotation is processed.
 767     return 0;
 768   }
 769 
 770   int value = _index_map_p->at(old_index);
 771   if (value == -1) {
 772     // the old_index is not mapped
 773     return 0;
 774   }
 775 
 776   return value;
 777 } // end find_new_index()
 778 
 779 
 780 // Returns true if the current mismatch is due to a resolved/unresolved
 781 // class pair. Otherwise, returns false.
 782 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
 783        int index1, constantPoolHandle cp2, int index2) {
 784 
 785   jbyte t1 = cp1->tag_at(index1).value();
 786   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 787     return false;  // wrong entry type; not our special case
 788   }
 789 
 790   jbyte t2 = cp2->tag_at(index2).value();
 791   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 792     return false;  // wrong entry type; not our special case
 793   }
 794 
 795   if (t1 == t2) {
 796     return false;  // not a mismatch; not our special case
 797   }
 798 
 799   char *s1 = cp1->klass_name_at(index1)->as_C_string();
 800   char *s2 = cp2->klass_name_at(index2)->as_C_string();
 801   if (strcmp(s1, s2) != 0) {
 802     return false;  // strings don't match; not our special case
 803   }
 804 
 805   return true;  // made it through the gauntlet; this is our special case
 806 } // end is_unresolved_class_mismatch()
 807 
 808 
 809 // Returns true if the current mismatch is due to a resolved/unresolved
 810 // string pair. Otherwise, returns false.
 811 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,
 812        int index1, constantPoolHandle cp2, int index2) {
 813 
 814   jbyte t1 = cp1->tag_at(index1).value();
 815   if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {
 816     return false;  // wrong entry type; not our special case
 817   }
 818 
 819   jbyte t2 = cp2->tag_at(index2).value();
 820   if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {
 821     return false;  // wrong entry type; not our special case
 822   }
 823 
 824   if (t1 == t2) {
 825     return false;  // not a mismatch; not our special case
 826   }
 827 
 828   char *s1 = cp1->string_at_noresolve(index1);
 829   char *s2 = cp2->string_at_noresolve(index2);
 830   if (strcmp(s1, s2) != 0) {
 831     return false;  // strings don't match; not our special case
 832   }
 833 
 834   return true;  // made it through the gauntlet; this is our special case
 835 } // end is_unresolved_string_mismatch()
 836 
 837 
 838 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
 839   // For consistency allocate memory using os::malloc wrapper.
 840   _scratch_classes = (instanceKlassHandle *)
 841     os::malloc(sizeof(instanceKlassHandle) * _class_count);
 842   if (_scratch_classes == NULL) {
 843     return JVMTI_ERROR_OUT_OF_MEMORY;
 844   }
 845 
 846   ResourceMark rm(THREAD);
 847 
 848   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
 849   // state can only be NULL if the current thread is exiting which
 850   // should not happen since we're trying to do a RedefineClasses
 851   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
 852   for (int i = 0; i < _class_count; i++) {
 853     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 854     // classes for primitives cannot be redefined
 855     if (!is_modifiable_class(mirror)) {
 856       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
 857     }
 858     klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
 859     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
 860     Symbol*  the_class_sym = the_class->name();
 861 
 862     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 863     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
 864       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
 865       the_class->external_name(), _class_load_kind,
 866       os::available_memory() >> 10));
 867 
 868     ClassFileStream st((u1*) _class_defs[i].class_bytes,
 869       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
 870 
 871     // Parse the stream.
 872     Handle the_class_loader(THREAD, the_class->class_loader());
 873     Handle protection_domain(THREAD, the_class->protection_domain());
 874     // Set redefined class handle in JvmtiThreadState class.
 875     // This redefined class is sent to agent event handler for class file
 876     // load hook event.
 877     state->set_class_being_redefined(&the_class, _class_load_kind);
 878 
 879     klassOop k = SystemDictionary::parse_stream(the_class_sym,
 880                                                 the_class_loader,
 881                                                 protection_domain,
 882                                                 &st,
 883                                                 THREAD);
 884     // Clear class_being_redefined just to be sure.
 885     state->clear_class_being_redefined();
 886 
 887     // TODO: if this is retransform, and nothing changed we can skip it
 888 
 889     instanceKlassHandle scratch_class (THREAD, k);
 890 
 891     if (HAS_PENDING_EXCEPTION) {
 892       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 893       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 894       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
 895         ex_name->as_C_string()));
 896       CLEAR_PENDING_EXCEPTION;
 897 
 898       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
 899         return JVMTI_ERROR_UNSUPPORTED_VERSION;
 900       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
 901         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
 902       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
 903         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
 904       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
 905         // The message will be "XXX (wrong name: YYY)"
 906         return JVMTI_ERROR_NAMES_DONT_MATCH;
 907       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 908         return JVMTI_ERROR_OUT_OF_MEMORY;
 909       } else {  // Just in case more exceptions can be thrown..
 910         return JVMTI_ERROR_FAILS_VERIFICATION;
 911       }
 912     }
 913 
 914     // Ensure class is linked before redefine
 915     if (!the_class->is_linked()) {
 916       the_class->link_class(THREAD);
 917       if (HAS_PENDING_EXCEPTION) {
 918         Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 919         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 920         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
 921           ex_name->as_C_string()));
 922         CLEAR_PENDING_EXCEPTION;
 923         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 924           return JVMTI_ERROR_OUT_OF_MEMORY;
 925         } else {
 926           return JVMTI_ERROR_INTERNAL;
 927         }
 928       }
 929     }
 930 
 931     // Do the validity checks in compare_and_normalize_class_versions()
 932     // before verifying the byte codes. By doing these checks first, we
 933     // limit the number of functions that require redirection from
 934     // the_class to scratch_class. In particular, we don't have to
 935     // modify JNI GetSuperclass() and thus won't change its performance.
 936     jvmtiError res = compare_and_normalize_class_versions(the_class,
 937                        scratch_class);
 938     if (res != JVMTI_ERROR_NONE) {
 939       return res;
 940     }
 941 
 942     // verify what the caller passed us
 943     {
 944       // The bug 6214132 caused the verification to fail.
 945       // Information about the_class and scratch_class is temporarily
 946       // recorded into jvmtiThreadState. This data is used to redirect
 947       // the_class to scratch_class in the JVM_* functions called by the
 948       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
 949       // description.
 950       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
 951       Verifier::verify(
 952         scratch_class, Verifier::ThrowException, true, THREAD);
 953     }
 954 
 955     if (HAS_PENDING_EXCEPTION) {
 956       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 957       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 958       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
 959         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
 960       CLEAR_PENDING_EXCEPTION;
 961       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 962         return JVMTI_ERROR_OUT_OF_MEMORY;
 963       } else {
 964         // tell the caller the bytecodes are bad
 965         return JVMTI_ERROR_FAILS_VERIFICATION;
 966       }
 967     }
 968 
 969     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
 970     if (res != JVMTI_ERROR_NONE) {
 971       return res;
 972     }
 973 
 974     if (VerifyMergedCPBytecodes) {
 975       // verify what we have done during constant pool merging
 976       {
 977         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
 978         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
 979       }
 980 
 981       if (HAS_PENDING_EXCEPTION) {
 982         Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
 983         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 984         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
 985           ("verify_byte_codes post merge-CP exception: '%s'",
 986           ex_name->as_C_string()));
 987         CLEAR_PENDING_EXCEPTION;
 988         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
 989           return JVMTI_ERROR_OUT_OF_MEMORY;
 990         } else {
 991           // tell the caller that constant pool merging screwed up
 992           return JVMTI_ERROR_INTERNAL;
 993         }
 994       }
 995     }
 996 
 997     Rewriter::rewrite(scratch_class, THREAD);
 998     if (!HAS_PENDING_EXCEPTION) {
 999       Rewriter::relocate_and_link(scratch_class, THREAD);
1000     }
1001     if (HAS_PENDING_EXCEPTION) {
1002       Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
1003       CLEAR_PENDING_EXCEPTION;
1004       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1005         return JVMTI_ERROR_OUT_OF_MEMORY;
1006       } else {
1007         return JVMTI_ERROR_INTERNAL;
1008       }
1009     }
1010 
1011     _scratch_classes[i] = scratch_class;
1012 
1013     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1014     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1015       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1016       the_class->external_name(), os::available_memory() >> 10));
1017   }
1018 
1019   return JVMTI_ERROR_NONE;
1020 }
1021 
1022 
1023 // Map old_index to new_index as needed. scratch_cp is only needed
1024 // for RC_TRACE() calls.
1025 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1026        int old_index, int new_index) {
1027   if (find_new_index(old_index) != 0) {
1028     // old_index is already mapped
1029     return;
1030   }
1031 
1032   if (old_index == new_index) {
1033     // no mapping is needed
1034     return;
1035   }
1036 
1037   _index_map_p->at_put(old_index, new_index);
1038   _index_map_count++;
1039 
1040   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1041     scratch_cp->tag_at(old_index).value(), old_index, new_index));
1042 } // end map_index()
1043 
1044 
1045 // Merge old_cp and scratch_cp and return the results of the merge via
1046 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1047 // merge_cp_length_p. The entries in old_cp occupy the same locations
1048 // in *merge_cp_p. Also creates a map of indices from entries in
1049 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1050 // entries are only created for entries in scratch_cp that occupy a
1051 // different location in *merged_cp_p.
1052 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1053        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1054        int *merge_cp_length_p, TRAPS) {
1055 
1056   if (merge_cp_p == NULL) {
1057     assert(false, "caller must provide scatch constantPool");
1058     return false; // robustness
1059   }
1060   if (merge_cp_length_p == NULL) {
1061     assert(false, "caller must provide scatch CP length");
1062     return false; // robustness
1063   }
1064   // Worst case we need old_cp->length() + scratch_cp()->length(),
1065   // but the caller might be smart so make sure we have at least
1066   // the minimum.
1067   if ((*merge_cp_p)->length() < old_cp->length()) {
1068     assert(false, "merge area too small");
1069     return false; // robustness
1070   }
1071 
1072   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1073     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1074     scratch_cp->length()));
1075 
1076   {
1077     // Pass 0:
1078     // The old_cp is copied to *merge_cp_p; this means that any code
1079     // using old_cp does not have to change. This work looks like a
1080     // perfect fit for constantPoolOop::copy_cp_to(), but we need to
1081     // handle one special case:
1082     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1083     // This will make verification happy.
1084 
1085     int old_i;  // index into old_cp
1086 
1087     // index zero (0) is not used in constantPools
1088     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1089       // leave debugging crumb
1090       jbyte old_tag = old_cp->tag_at(old_i).value();
1091       switch (old_tag) {
1092       case JVM_CONSTANT_Class:
1093       case JVM_CONSTANT_UnresolvedClass:
1094         // revert the copy to JVM_CONSTANT_UnresolvedClass
1095         // May be resolving while calling this so do the same for
1096         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1097         (*merge_cp_p)->unresolved_klass_at_put(old_i,
1098           old_cp->klass_name_at(old_i));
1099         break;
1100 
1101       case JVM_CONSTANT_Double:
1102       case JVM_CONSTANT_Long:
1103         // just copy the entry to *merge_cp_p, but double and long take
1104         // two constant pool entries
1105         constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1106         old_i++;
1107         break;
1108 
1109       default:
1110         // just copy the entry to *merge_cp_p
1111         constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1112         break;
1113       }
1114     } // end for each old_cp entry
1115 
1116     // We don't need to sanity check that *merge_cp_length_p is within
1117     // *merge_cp_p bounds since we have the minimum on-entry check above.
1118     (*merge_cp_length_p) = old_i;
1119   }
1120 
1121   // merge_cp_len should be the same as old_cp->length() at this point
1122   // so this trace message is really a "warm-and-breathing" message.
1123   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1124     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1125 
1126   int scratch_i;  // index into scratch_cp
1127   {
1128     // Pass 1a:
1129     // Compare scratch_cp entries to the old_cp entries that we have
1130     // already copied to *merge_cp_p. In this pass, we are eliminating
1131     // exact duplicates (matching entry at same index) so we only
1132     // compare entries in the common indice range.
1133     int increment = 1;
1134     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1135     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1136       switch (scratch_cp->tag_at(scratch_i).value()) {
1137       case JVM_CONSTANT_Double:
1138       case JVM_CONSTANT_Long:
1139         // double and long take two constant pool entries
1140         increment = 2;
1141         break;
1142 
1143       default:
1144         increment = 1;
1145         break;
1146       }
1147 
1148       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1149         scratch_i, CHECK_0);
1150       if (match) {
1151         // found a match at the same index so nothing more to do
1152         continue;
1153       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1154                                               *merge_cp_p, scratch_i)) {
1155         // The mismatch in compare_entry_to() above is because of a
1156         // resolved versus unresolved class entry at the same index
1157         // with the same string value. Since Pass 0 reverted any
1158         // class entries to unresolved class entries in *merge_cp_p,
1159         // we go with the unresolved class entry.
1160         continue;
1161       } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
1162                                                *merge_cp_p, scratch_i)) {
1163         // The mismatch in compare_entry_to() above is because of a
1164         // resolved versus unresolved string entry at the same index
1165         // with the same string value. We can live with whichever
1166         // happens to be at scratch_i in *merge_cp_p.
1167         continue;
1168       }
1169 
1170       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1171         CHECK_0);
1172       if (found_i != 0) {
1173         guarantee(found_i != scratch_i,
1174           "compare_entry_to() and find_matching_entry() do not agree");
1175 
1176         // Found a matching entry somewhere else in *merge_cp_p so
1177         // just need a mapping entry.
1178         map_index(scratch_cp, scratch_i, found_i);
1179         continue;
1180       }
1181 
1182       // The find_matching_entry() call above could fail to find a match
1183       // due to a resolved versus unresolved class or string entry situation
1184       // like we solved above with the is_unresolved_*_mismatch() calls.
1185       // However, we would have to call is_unresolved_*_mismatch() over
1186       // all of *merge_cp_p (potentially) and that doesn't seem to be
1187       // worth the time.
1188 
1189       // No match found so we have to append this entry and any unique
1190       // referenced entries to *merge_cp_p.
1191       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1192         CHECK_0);
1193     }
1194   }
1195 
1196   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1197     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1198     *merge_cp_length_p, scratch_i, _index_map_count));
1199 
1200   if (scratch_i < scratch_cp->length()) {
1201     // Pass 1b:
1202     // old_cp is smaller than scratch_cp so there are entries in
1203     // scratch_cp that we have not yet processed. We take care of
1204     // those now.
1205     int increment = 1;
1206     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1207       switch (scratch_cp->tag_at(scratch_i).value()) {
1208       case JVM_CONSTANT_Double:
1209       case JVM_CONSTANT_Long:
1210         // double and long take two constant pool entries
1211         increment = 2;
1212         break;
1213 
1214       default:
1215         increment = 1;
1216         break;
1217       }
1218 
1219       int found_i =
1220         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1221       if (found_i != 0) {
1222         // Found a matching entry somewhere else in *merge_cp_p so
1223         // just need a mapping entry.
1224         map_index(scratch_cp, scratch_i, found_i);
1225         continue;
1226       }
1227 
1228       // No match found so we have to append this entry and any unique
1229       // referenced entries to *merge_cp_p.
1230       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1231         CHECK_0);
1232     }
1233 
1234     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1235       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1236       *merge_cp_length_p, scratch_i, _index_map_count));
1237   }
1238 
1239   return true;
1240 } // end merge_constant_pools()
1241 
1242 
1243 // Merge constant pools between the_class and scratch_class and
1244 // potentially rewrite bytecodes in scratch_class to use the merged
1245 // constant pool.
1246 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1247              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1248              TRAPS) {
1249   // worst case merged constant pool length is old and new combined
1250   int merge_cp_length = the_class->constants()->length()
1251         + scratch_class->constants()->length();
1252 
1253   constantPoolHandle old_cp(THREAD, the_class->constants());
1254   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1255 
1256   // Constant pools are not easily reused so we allocate a new one
1257   // each time.
1258   // merge_cp is created unsafe for concurrent GC processing.  It
1259   // should be marked safe before discarding it. Even though
1260   // garbage,  if it crosses a card boundary, it may be scanned
1261   // in order to find the start of the first complete object on the card.
1262   constantPoolHandle merge_cp(THREAD,
1263     oopFactory::new_constantPool(merge_cp_length,
1264                                  oopDesc::IsUnsafeConc,
1265                                  THREAD));
1266   int orig_length = old_cp->orig_length();
1267   if (orig_length == 0) {
1268     // This old_cp is an actual original constant pool. We save
1269     // the original length in the merged constant pool so that
1270     // merge_constant_pools() can be more efficient. If a constant
1271     // pool has a non-zero orig_length() value, then that constant
1272     // pool was created by a merge operation in RedefineClasses.
1273     merge_cp->set_orig_length(old_cp->length());
1274   } else {
1275     // This old_cp is a merged constant pool from a previous
1276     // RedefineClasses() calls so just copy the orig_length()
1277     // value.
1278     merge_cp->set_orig_length(old_cp->orig_length());
1279   }
1280 
1281   ResourceMark rm(THREAD);
1282   _index_map_count = 0;
1283   _index_map_p = new intArray(scratch_cp->length(), -1);
1284 
1285   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1286                   &merge_cp_length, THREAD);
1287   if (!result) {
1288     // The merge can fail due to memory allocation failure or due
1289     // to robustness checks.
1290     return JVMTI_ERROR_INTERNAL;
1291   }
1292 
1293   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1294     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1295 
1296   if (_index_map_count == 0) {
1297     // there is nothing to map between the new and merged constant pools
1298 
1299     if (old_cp->length() == scratch_cp->length()) {
1300       // The old and new constant pools are the same length and the
1301       // index map is empty. This means that the three constant pools
1302       // are equivalent (but not the same). Unfortunately, the new
1303       // constant pool has not gone through link resolution nor have
1304       // the new class bytecodes gone through constant pool cache
1305       // rewriting so we can't use the old constant pool with the new
1306       // class.
1307 
1308       merge_cp()->set_is_conc_safe(true);
1309       merge_cp = constantPoolHandle();  // toss the merged constant pool
1310     } else if (old_cp->length() < scratch_cp->length()) {
1311       // The old constant pool has fewer entries than the new constant
1312       // pool and the index map is empty. This means the new constant
1313       // pool is a superset of the old constant pool. However, the old
1314       // class bytecodes have already gone through constant pool cache
1315       // rewriting so we can't use the new constant pool with the old
1316       // class.
1317 
1318       merge_cp()->set_is_conc_safe(true);
1319       merge_cp = constantPoolHandle();  // toss the merged constant pool
1320     } else {
1321       // The old constant pool has more entries than the new constant
1322       // pool and the index map is empty. This means that both the old
1323       // and merged constant pools are supersets of the new constant
1324       // pool.
1325 
1326       // Replace the new constant pool with a shrunken copy of the
1327       // merged constant pool; the previous new constant pool will
1328       // get GCed.
1329       set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1330         THREAD);
1331       // drop local ref to the merged constant pool
1332       merge_cp()->set_is_conc_safe(true);
1333       merge_cp = constantPoolHandle();
1334     }
1335   } else {
1336     if (RC_TRACE_ENABLED(0x00040000)) {
1337       // don't want to loop unless we are tracing
1338       int count = 0;
1339       for (int i = 1; i < _index_map_p->length(); i++) {
1340         int value = _index_map_p->at(i);
1341 
1342         if (value != -1) {
1343           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1344             ("index_map[%d]: old=%d new=%d", count, i, value));
1345           count++;
1346         }
1347       }
1348     }
1349 
1350     // We have entries mapped between the new and merged constant pools
1351     // so we have to rewrite some constant pool references.
1352     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1353       return JVMTI_ERROR_INTERNAL;
1354     }
1355 
1356     // Replace the new constant pool with a shrunken copy of the
1357     // merged constant pool so now the rewritten bytecodes have
1358     // valid references; the previous new constant pool will get
1359     // GCed.
1360     set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1361       THREAD);
1362     merge_cp()->set_is_conc_safe(true);
1363   }
1364   assert(old_cp()->is_conc_safe(), "Just checking");
1365   assert(scratch_cp()->is_conc_safe(), "Just checking");
1366 
1367   return JVMTI_ERROR_NONE;
1368 } // end merge_cp_and_rewrite()
1369 
1370 
1371 // Rewrite constant pool references in klass scratch_class.
1372 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1373        TRAPS) {
1374 
1375   // rewrite constant pool references in the methods:
1376   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1377     // propagate failure back to caller
1378     return false;
1379   }
1380 
1381   // rewrite constant pool references in the class_annotations:
1382   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1383     // propagate failure back to caller
1384     return false;
1385   }
1386 
1387   // rewrite constant pool references in the fields_annotations:
1388   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1389     // propagate failure back to caller
1390     return false;
1391   }
1392 
1393   // rewrite constant pool references in the methods_annotations:
1394   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1395     // propagate failure back to caller
1396     return false;
1397   }
1398 
1399   // rewrite constant pool references in the methods_parameter_annotations:
1400   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1401          THREAD)) {
1402     // propagate failure back to caller
1403     return false;
1404   }
1405 
1406   // rewrite constant pool references in the methods_default_annotations:
1407   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1408          THREAD)) {
1409     // propagate failure back to caller
1410     return false;
1411   }
1412 
1413   return true;
1414 } // end rewrite_cp_refs()
1415 
1416 
1417 // Rewrite constant pool references in the methods.
1418 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1419        instanceKlassHandle scratch_class, TRAPS) {
1420 
1421   objArrayHandle methods(THREAD, scratch_class->methods());
1422 
1423   if (methods.is_null() || methods->length() == 0) {
1424     // no methods so nothing to do
1425     return true;
1426   }
1427 
1428   // rewrite constant pool references in the methods:
1429   for (int i = methods->length() - 1; i >= 0; i--) {
1430     methodHandle method(THREAD, (methodOop)methods->obj_at(i));
1431     methodHandle new_method;
1432     rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1433     if (!new_method.is_null()) {
1434       // the method has been replaced so save the new method version
1435       methods->obj_at_put(i, new_method());
1436     }
1437   }
1438 
1439   return true;
1440 }
1441 
1442 
1443 // Rewrite constant pool references in the specific method. This code
1444 // was adapted from Rewriter::rewrite_method().
1445 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1446        methodHandle *new_method_p, TRAPS) {
1447 
1448   *new_method_p = methodHandle();  // default is no new method
1449 
1450   // We cache a pointer to the bytecodes here in code_base. If GC
1451   // moves the methodOop, then the bytecodes will also move which
1452   // will likely cause a crash. We create a No_Safepoint_Verifier
1453   // object to detect whether we pass a possible safepoint in this
1454   // code block.
1455   No_Safepoint_Verifier nsv;
1456 
1457   // Bytecodes and their length
1458   address code_base = method->code_base();
1459   int code_length = method->code_size();
1460 
1461   int bc_length;
1462   for (int bci = 0; bci < code_length; bci += bc_length) {
1463     address bcp = code_base + bci;
1464     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1465 
1466     bc_length = Bytecodes::length_for(c);
1467     if (bc_length == 0) {
1468       // More complicated bytecodes report a length of zero so
1469       // we have to try again a slightly different way.
1470       bc_length = Bytecodes::length_at(method(), bcp);
1471     }
1472 
1473     assert(bc_length != 0, "impossible bytecode length");
1474 
1475     switch (c) {
1476       case Bytecodes::_ldc:
1477       {
1478         int cp_index = *(bcp + 1);
1479         int new_index = find_new_index(cp_index);
1480 
1481         if (StressLdcRewrite && new_index == 0) {
1482           // If we are stressing ldc -> ldc_w rewriting, then we
1483           // always need a new_index value.
1484           new_index = cp_index;
1485         }
1486         if (new_index != 0) {
1487           // the original index is mapped so we have more work to do
1488           if (!StressLdcRewrite && new_index <= max_jubyte) {
1489             // The new value can still use ldc instead of ldc_w
1490             // unless we are trying to stress ldc -> ldc_w rewriting
1491             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1492               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1493               bcp, cp_index, new_index));
1494             *(bcp + 1) = new_index;
1495           } else {
1496             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1497               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1498               Bytecodes::name(c), bcp, cp_index, new_index));
1499             // the new value needs ldc_w instead of ldc
1500             u_char inst_buffer[4]; // max instruction size is 4 bytes
1501             bcp = (address)inst_buffer;
1502             // construct new instruction sequence
1503             *bcp = Bytecodes::_ldc_w;
1504             bcp++;
1505             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1506             // See comment below for difference between put_Java_u2()
1507             // and put_native_u2().
1508             Bytes::put_Java_u2(bcp, new_index);
1509 
1510             Relocator rc(method, NULL /* no RelocatorListener needed */);
1511             methodHandle m;
1512             {
1513               Pause_No_Safepoint_Verifier pnsv(&nsv);
1514 
1515               // ldc is 2 bytes and ldc_w is 3 bytes
1516               m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1517               if (m.is_null() || HAS_PENDING_EXCEPTION) {
1518                 guarantee(false, "insert_space_at() failed");
1519               }
1520             }
1521 
1522             // return the new method so that the caller can update
1523             // the containing class
1524             *new_method_p = method = m;
1525             // switch our bytecode processing loop from the old method
1526             // to the new method
1527             code_base = method->code_base();
1528             code_length = method->code_size();
1529             bcp = code_base + bci;
1530             c = (Bytecodes::Code)(*bcp);
1531             bc_length = Bytecodes::length_for(c);
1532             assert(bc_length != 0, "sanity check");
1533           } // end we need ldc_w instead of ldc
1534         } // end if there is a mapped index
1535       } break;
1536 
1537       // these bytecodes have a two-byte constant pool index
1538       case Bytecodes::_anewarray      : // fall through
1539       case Bytecodes::_checkcast      : // fall through
1540       case Bytecodes::_getfield       : // fall through
1541       case Bytecodes::_getstatic      : // fall through
1542       case Bytecodes::_instanceof     : // fall through
1543       case Bytecodes::_invokeinterface: // fall through
1544       case Bytecodes::_invokespecial  : // fall through
1545       case Bytecodes::_invokestatic   : // fall through
1546       case Bytecodes::_invokevirtual  : // fall through
1547       case Bytecodes::_ldc_w          : // fall through
1548       case Bytecodes::_ldc2_w         : // fall through
1549       case Bytecodes::_multianewarray : // fall through
1550       case Bytecodes::_new            : // fall through
1551       case Bytecodes::_putfield       : // fall through
1552       case Bytecodes::_putstatic      :
1553       {
1554         address p = bcp + 1;
1555         int cp_index = Bytes::get_Java_u2(p);
1556         int new_index = find_new_index(cp_index);
1557         if (new_index != 0) {
1558           // the original index is mapped so update w/ new value
1559           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1560             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1561             bcp, cp_index, new_index));
1562           // Rewriter::rewrite_method() uses put_native_u2() in this
1563           // situation because it is reusing the constant pool index
1564           // location for a native index into the constantPoolCache.
1565           // Since we are updating the constant pool index prior to
1566           // verification and constantPoolCache initialization, we
1567           // need to keep the new index in Java byte order.
1568           Bytes::put_Java_u2(p, new_index);
1569         }
1570       } break;
1571     }
1572   } // end for each bytecode
1573 } // end rewrite_cp_refs_in_method()
1574 
1575 
1576 // Rewrite constant pool references in the class_annotations field.
1577 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1578        instanceKlassHandle scratch_class, TRAPS) {
1579 
1580   typeArrayHandle class_annotations(THREAD,
1581     scratch_class->class_annotations());
1582   if (class_annotations.is_null() || class_annotations->length() == 0) {
1583     // no class_annotations so nothing to do
1584     return true;
1585   }
1586 
1587   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1588     ("class_annotations length=%d", class_annotations->length()));
1589 
1590   int byte_i = 0;  // byte index into class_annotations
1591   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1592            THREAD);
1593 }
1594 
1595 
1596 // Rewrite constant pool references in an annotations typeArray. This
1597 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1598 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1599 //
1600 // annotations_typeArray {
1601 //   u2 num_annotations;
1602 //   annotation annotations[num_annotations];
1603 // }
1604 //
1605 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1606        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1607 
1608   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1609     // not enough room for num_annotations field
1610     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1611       ("length() is too small for num_annotations field"));
1612     return false;
1613   }
1614 
1615   u2 num_annotations = Bytes::get_Java_u2((address)
1616                          annotations_typeArray->byte_at_addr(byte_i_ref));
1617   byte_i_ref += 2;
1618 
1619   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1620     ("num_annotations=%d", num_annotations));
1621 
1622   int calc_num_annotations = 0;
1623   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1624     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1625            byte_i_ref, THREAD)) {
1626       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1627         ("bad annotation_struct at %d", calc_num_annotations));
1628       // propagate failure back to caller
1629       return false;
1630     }
1631   }
1632   assert(num_annotations == calc_num_annotations, "sanity check");
1633 
1634   return true;
1635 } // end rewrite_cp_refs_in_annotations_typeArray()
1636 
1637 
1638 // Rewrite constant pool references in the annotation struct portion of
1639 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1640 // the 2nd-edition of the VM spec:
1641 //
1642 // struct annotation {
1643 //   u2 type_index;
1644 //   u2 num_element_value_pairs;
1645 //   {
1646 //     u2 element_name_index;
1647 //     element_value value;
1648 //   } element_value_pairs[num_element_value_pairs];
1649 // }
1650 //
1651 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1652        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1653   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1654     // not enough room for smallest annotation_struct
1655     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1656       ("length() is too small for annotation_struct"));
1657     return false;
1658   }
1659 
1660   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1661                     byte_i_ref, "mapped old type_index=%d", THREAD);
1662 
1663   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1664                                  annotations_typeArray->byte_at_addr(
1665                                  byte_i_ref));
1666   byte_i_ref += 2;
1667 
1668   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1669     ("type_index=%d  num_element_value_pairs=%d", type_index,
1670     num_element_value_pairs));
1671 
1672   int calc_num_element_value_pairs = 0;
1673   for (; calc_num_element_value_pairs < num_element_value_pairs;
1674        calc_num_element_value_pairs++) {
1675     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1676       // not enough room for another element_name_index, let alone
1677       // the rest of another component
1678       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1679         ("length() is too small for element_name_index"));
1680       return false;
1681     }
1682 
1683     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1684                               annotations_typeArray, byte_i_ref,
1685                               "mapped old element_name_index=%d", THREAD);
1686 
1687     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1688       ("element_name_index=%d", element_name_index));
1689 
1690     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1691            byte_i_ref, THREAD)) {
1692       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1693         ("bad element_value at %d", calc_num_element_value_pairs));
1694       // propagate failure back to caller
1695       return false;
1696     }
1697   } // end for each component
1698   assert(num_element_value_pairs == calc_num_element_value_pairs,
1699     "sanity check");
1700 
1701   return true;
1702 } // end rewrite_cp_refs_in_annotation_struct()
1703 
1704 
1705 // Rewrite a constant pool reference at the current position in
1706 // annotations_typeArray if needed. Returns the original constant
1707 // pool reference if a rewrite was not needed or the new constant
1708 // pool reference if a rewrite was needed.
1709 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1710      typeArrayHandle annotations_typeArray, int &byte_i_ref,
1711      const char * trace_mesg, TRAPS) {
1712 
1713   address cp_index_addr = (address)
1714     annotations_typeArray->byte_at_addr(byte_i_ref);
1715   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1716   u2 new_cp_index = find_new_index(old_cp_index);
1717   if (new_cp_index != 0) {
1718     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1719     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1720     old_cp_index = new_cp_index;
1721   }
1722   byte_i_ref += 2;
1723   return old_cp_index;
1724 }
1725 
1726 
1727 // Rewrite constant pool references in the element_value portion of an
1728 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1729 // the 2nd-edition of the VM spec:
1730 //
1731 // struct element_value {
1732 //   u1 tag;
1733 //   union {
1734 //     u2 const_value_index;
1735 //     {
1736 //       u2 type_name_index;
1737 //       u2 const_name_index;
1738 //     } enum_const_value;
1739 //     u2 class_info_index;
1740 //     annotation annotation_value;
1741 //     struct {
1742 //       u2 num_values;
1743 //       element_value values[num_values];
1744 //     } array_value;
1745 //   } value;
1746 // }
1747 //
1748 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1749        typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1750 
1751   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1752     // not enough room for a tag let alone the rest of an element_value
1753     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1754       ("length() is too small for a tag"));
1755     return false;
1756   }
1757 
1758   u1 tag = annotations_typeArray->byte_at(byte_i_ref);
1759   byte_i_ref++;
1760   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1761 
1762   switch (tag) {
1763     // These BaseType tag values are from Table 4.2 in VM spec:
1764     case 'B':  // byte
1765     case 'C':  // char
1766     case 'D':  // double
1767     case 'F':  // float
1768     case 'I':  // int
1769     case 'J':  // long
1770     case 'S':  // short
1771     case 'Z':  // boolean
1772 
1773     // The remaining tag values are from Table 4.8 in the 2nd-edition of
1774     // the VM spec:
1775     case 's':
1776     {
1777       // For the above tag values (including the BaseType values),
1778       // value.const_value_index is right union field.
1779 
1780       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1781         // not enough room for a const_value_index
1782         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1783           ("length() is too small for a const_value_index"));
1784         return false;
1785       }
1786 
1787       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1788                                annotations_typeArray, byte_i_ref,
1789                                "mapped old const_value_index=%d", THREAD);
1790 
1791       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1792         ("const_value_index=%d", const_value_index));
1793     } break;
1794 
1795     case 'e':
1796     {
1797       // for the above tag value, value.enum_const_value is right union field
1798 
1799       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1800         // not enough room for a enum_const_value
1801         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1802           ("length() is too small for a enum_const_value"));
1803         return false;
1804       }
1805 
1806       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1807                              annotations_typeArray, byte_i_ref,
1808                              "mapped old type_name_index=%d", THREAD);
1809 
1810       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1811                               annotations_typeArray, byte_i_ref,
1812                               "mapped old const_name_index=%d", THREAD);
1813 
1814       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1815         ("type_name_index=%d  const_name_index=%d", type_name_index,
1816         const_name_index));
1817     } break;
1818 
1819     case 'c':
1820     {
1821       // for the above tag value, value.class_info_index is right union field
1822 
1823       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1824         // not enough room for a class_info_index
1825         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1826           ("length() is too small for a class_info_index"));
1827         return false;
1828       }
1829 
1830       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1831                               annotations_typeArray, byte_i_ref,
1832                               "mapped old class_info_index=%d", THREAD);
1833 
1834       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1835         ("class_info_index=%d", class_info_index));
1836     } break;
1837 
1838     case '@':
1839       // For the above tag value, value.attr_value is the right union
1840       // field. This is a nested annotation.
1841       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1842              byte_i_ref, THREAD)) {
1843         // propagate failure back to caller
1844         return false;
1845       }
1846       break;
1847 
1848     case '[':
1849     {
1850       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1851         // not enough room for a num_values field
1852         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1853           ("length() is too small for a num_values field"));
1854         return false;
1855       }
1856 
1857       // For the above tag value, value.array_value is the right union
1858       // field. This is an array of nested element_value.
1859       u2 num_values = Bytes::get_Java_u2((address)
1860                         annotations_typeArray->byte_at_addr(byte_i_ref));
1861       byte_i_ref += 2;
1862       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1863 
1864       int calc_num_values = 0;
1865       for (; calc_num_values < num_values; calc_num_values++) {
1866         if (!rewrite_cp_refs_in_element_value(
1867                annotations_typeArray, byte_i_ref, THREAD)) {
1868           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1869             ("bad nested element_value at %d", calc_num_values));
1870           // propagate failure back to caller
1871           return false;
1872         }
1873       }
1874       assert(num_values == calc_num_values, "sanity check");
1875     } break;
1876 
1877     default:
1878       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1879       return false;
1880   } // end decode tag field
1881 
1882   return true;
1883 } // end rewrite_cp_refs_in_element_value()
1884 
1885 
1886 // Rewrite constant pool references in a fields_annotations field.
1887 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1888        instanceKlassHandle scratch_class, TRAPS) {
1889 
1890   objArrayHandle fields_annotations(THREAD,
1891     scratch_class->fields_annotations());
1892 
1893   if (fields_annotations.is_null() || fields_annotations->length() == 0) {
1894     // no fields_annotations so nothing to do
1895     return true;
1896   }
1897 
1898   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1899     ("fields_annotations length=%d", fields_annotations->length()));
1900 
1901   for (int i = 0; i < fields_annotations->length(); i++) {
1902     typeArrayHandle field_annotations(THREAD,
1903       (typeArrayOop)fields_annotations->obj_at(i));
1904     if (field_annotations.is_null() || field_annotations->length() == 0) {
1905       // this field does not have any annotations so skip it
1906       continue;
1907     }
1908 
1909     int byte_i = 0;  // byte index into field_annotations
1910     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1911            THREAD)) {
1912       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1913         ("bad field_annotations at %d", i));
1914       // propagate failure back to caller
1915       return false;
1916     }
1917   }
1918 
1919   return true;
1920 } // end rewrite_cp_refs_in_fields_annotations()
1921 
1922 
1923 // Rewrite constant pool references in a methods_annotations field.
1924 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1925        instanceKlassHandle scratch_class, TRAPS) {
1926 
1927   objArrayHandle methods_annotations(THREAD,
1928     scratch_class->methods_annotations());
1929 
1930   if (methods_annotations.is_null() || methods_annotations->length() == 0) {
1931     // no methods_annotations so nothing to do
1932     return true;
1933   }
1934 
1935   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1936     ("methods_annotations length=%d", methods_annotations->length()));
1937 
1938   for (int i = 0; i < methods_annotations->length(); i++) {
1939     typeArrayHandle method_annotations(THREAD,
1940       (typeArrayOop)methods_annotations->obj_at(i));
1941     if (method_annotations.is_null() || method_annotations->length() == 0) {
1942       // this method does not have any annotations so skip it
1943       continue;
1944     }
1945 
1946     int byte_i = 0;  // byte index into method_annotations
1947     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
1948            THREAD)) {
1949       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1950         ("bad method_annotations at %d", i));
1951       // propagate failure back to caller
1952       return false;
1953     }
1954   }
1955 
1956   return true;
1957 } // end rewrite_cp_refs_in_methods_annotations()
1958 
1959 
1960 // Rewrite constant pool references in a methods_parameter_annotations
1961 // field. This "structure" is adapted from the
1962 // RuntimeVisibleParameterAnnotations_attribute described in section
1963 // 4.8.17 of the 2nd-edition of the VM spec:
1964 //
1965 // methods_parameter_annotations_typeArray {
1966 //   u1 num_parameters;
1967 //   {
1968 //     u2 num_annotations;
1969 //     annotation annotations[num_annotations];
1970 //   } parameter_annotations[num_parameters];
1971 // }
1972 //
1973 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
1974        instanceKlassHandle scratch_class, TRAPS) {
1975 
1976   objArrayHandle methods_parameter_annotations(THREAD,
1977     scratch_class->methods_parameter_annotations());
1978 
1979   if (methods_parameter_annotations.is_null()
1980       || methods_parameter_annotations->length() == 0) {
1981     // no methods_parameter_annotations so nothing to do
1982     return true;
1983   }
1984 
1985   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1986     ("methods_parameter_annotations length=%d",
1987     methods_parameter_annotations->length()));
1988 
1989   for (int i = 0; i < methods_parameter_annotations->length(); i++) {
1990     typeArrayHandle method_parameter_annotations(THREAD,
1991       (typeArrayOop)methods_parameter_annotations->obj_at(i));
1992     if (method_parameter_annotations.is_null()
1993         || method_parameter_annotations->length() == 0) {
1994       // this method does not have any parameter annotations so skip it
1995       continue;
1996     }
1997 
1998     if (method_parameter_annotations->length() < 1) {
1999       // not enough room for a num_parameters field
2000       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2001         ("length() is too small for a num_parameters field at %d", i));
2002       return false;
2003     }
2004 
2005     int byte_i = 0;  // byte index into method_parameter_annotations
2006 
2007     u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
2008     byte_i++;
2009 
2010     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2011       ("num_parameters=%d", num_parameters));
2012 
2013     int calc_num_parameters = 0;
2014     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2015       if (!rewrite_cp_refs_in_annotations_typeArray(
2016              method_parameter_annotations, byte_i, THREAD)) {
2017         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2018           ("bad method_parameter_annotations at %d", calc_num_parameters));
2019         // propagate failure back to caller
2020         return false;
2021       }
2022     }
2023     assert(num_parameters == calc_num_parameters, "sanity check");
2024   }
2025 
2026   return true;
2027 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2028 
2029 
2030 // Rewrite constant pool references in a methods_default_annotations
2031 // field. This "structure" is adapted from the AnnotationDefault_attribute
2032 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2033 //
2034 // methods_default_annotations_typeArray {
2035 //   element_value default_value;
2036 // }
2037 //
2038 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2039        instanceKlassHandle scratch_class, TRAPS) {
2040 
2041   objArrayHandle methods_default_annotations(THREAD,
2042     scratch_class->methods_default_annotations());
2043 
2044   if (methods_default_annotations.is_null()
2045       || methods_default_annotations->length() == 0) {
2046     // no methods_default_annotations so nothing to do
2047     return true;
2048   }
2049 
2050   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2051     ("methods_default_annotations length=%d",
2052     methods_default_annotations->length()));
2053 
2054   for (int i = 0; i < methods_default_annotations->length(); i++) {
2055     typeArrayHandle method_default_annotations(THREAD,
2056       (typeArrayOop)methods_default_annotations->obj_at(i));
2057     if (method_default_annotations.is_null()
2058         || method_default_annotations->length() == 0) {
2059       // this method does not have any default annotations so skip it
2060       continue;
2061     }
2062 
2063     int byte_i = 0;  // byte index into method_default_annotations
2064 
2065     if (!rewrite_cp_refs_in_element_value(
2066            method_default_annotations, byte_i, THREAD)) {
2067       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2068         ("bad default element_value at %d", i));
2069       // propagate failure back to caller
2070       return false;
2071     }
2072   }
2073 
2074   return true;
2075 } // end rewrite_cp_refs_in_methods_default_annotations()
2076 
2077 
2078 // Rewrite constant pool references in the method's stackmap table.
2079 // These "structures" are adapted from the StackMapTable_attribute that
2080 // is described in section 4.8.4 of the 6.0 version of the VM spec
2081 // (dated 2005.10.26):
2082 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2083 //
2084 // stack_map {
2085 //   u2 number_of_entries;
2086 //   stack_map_frame entries[number_of_entries];
2087 // }
2088 //
2089 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2090        methodHandle method, TRAPS) {
2091 
2092   if (!method->has_stackmap_table()) {
2093     return;
2094   }
2095 
2096   typeArrayOop stackmap_data = method->stackmap_data();
2097   address stackmap_p = (address)stackmap_data->byte_at_addr(0);
2098   address stackmap_end = stackmap_p + stackmap_data->length();
2099 
2100   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2101   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2102   stackmap_p += 2;
2103 
2104   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2105     ("number_of_entries=%u", number_of_entries));
2106 
2107   // walk through each stack_map_frame
2108   u2 calc_number_of_entries = 0;
2109   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2110     // The stack_map_frame structure is a u1 frame_type followed by
2111     // 0 or more bytes of data:
2112     //
2113     // union stack_map_frame {
2114     //   same_frame;
2115     //   same_locals_1_stack_item_frame;
2116     //   same_locals_1_stack_item_frame_extended;
2117     //   chop_frame;
2118     //   same_frame_extended;
2119     //   append_frame;
2120     //   full_frame;
2121     // }
2122 
2123     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2124     // The Linux compiler does not like frame_type to be u1 or u2. It
2125     // issues the following warning for the first if-statement below:
2126     //
2127     // "warning: comparison is always true due to limited range of data type"
2128     //
2129     u4 frame_type = *stackmap_p;
2130     stackmap_p++;
2131 
2132     // same_frame {
2133     //   u1 frame_type = SAME; /* 0-63 */
2134     // }
2135     if (frame_type >= 0 && frame_type <= 63) {
2136       // nothing more to do for same_frame
2137     }
2138 
2139     // same_locals_1_stack_item_frame {
2140     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2141     //   verification_type_info stack[1];
2142     // }
2143     else if (frame_type >= 64 && frame_type <= 127) {
2144       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2145         calc_number_of_entries, frame_type, THREAD);
2146     }
2147 
2148     // reserved for future use
2149     else if (frame_type >= 128 && frame_type <= 246) {
2150       // nothing more to do for reserved frame_types
2151     }
2152 
2153     // same_locals_1_stack_item_frame_extended {
2154     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2155     //   u2 offset_delta;
2156     //   verification_type_info stack[1];
2157     // }
2158     else if (frame_type == 247) {
2159       stackmap_p += 2;
2160       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2161         calc_number_of_entries, frame_type, THREAD);
2162     }
2163 
2164     // chop_frame {
2165     //   u1 frame_type = CHOP; /* 248-250 */
2166     //   u2 offset_delta;
2167     // }
2168     else if (frame_type >= 248 && frame_type <= 250) {
2169       stackmap_p += 2;
2170     }
2171 
2172     // same_frame_extended {
2173     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2174     //   u2 offset_delta;
2175     // }
2176     else if (frame_type == 251) {
2177       stackmap_p += 2;
2178     }
2179 
2180     // append_frame {
2181     //   u1 frame_type = APPEND; /* 252-254 */
2182     //   u2 offset_delta;
2183     //   verification_type_info locals[frame_type - 251];
2184     // }
2185     else if (frame_type >= 252 && frame_type <= 254) {
2186       assert(stackmap_p + 2 <= stackmap_end,
2187         "no room for offset_delta");
2188       stackmap_p += 2;
2189       u1 len = frame_type - 251;
2190       for (u1 i = 0; i < len; i++) {
2191         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2192           calc_number_of_entries, frame_type, THREAD);
2193       }
2194     }
2195 
2196     // full_frame {
2197     //   u1 frame_type = FULL_FRAME; /* 255 */
2198     //   u2 offset_delta;
2199     //   u2 number_of_locals;
2200     //   verification_type_info locals[number_of_locals];
2201     //   u2 number_of_stack_items;
2202     //   verification_type_info stack[number_of_stack_items];
2203     // }
2204     else if (frame_type == 255) {
2205       assert(stackmap_p + 2 + 2 <= stackmap_end,
2206         "no room for smallest full_frame");
2207       stackmap_p += 2;
2208 
2209       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2210       stackmap_p += 2;
2211 
2212       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2213         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2214           calc_number_of_entries, frame_type, THREAD);
2215       }
2216 
2217       // Use the largest size for the number_of_stack_items, but only get
2218       // the right number of bytes.
2219       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2220       stackmap_p += 2;
2221 
2222       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2223         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2224           calc_number_of_entries, frame_type, THREAD);
2225       }
2226     }
2227   } // end while there is a stack_map_frame
2228   assert(number_of_entries == calc_number_of_entries, "sanity check");
2229 } // end rewrite_cp_refs_in_stack_map_table()
2230 
2231 
2232 // Rewrite constant pool references in the verification type info
2233 // portion of the method's stackmap table. These "structures" are
2234 // adapted from the StackMapTable_attribute that is described in
2235 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2236 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2237 //
2238 // The verification_type_info structure is a u1 tag followed by 0 or
2239 // more bytes of data:
2240 //
2241 // union verification_type_info {
2242 //   Top_variable_info;
2243 //   Integer_variable_info;
2244 //   Float_variable_info;
2245 //   Long_variable_info;
2246 //   Double_variable_info;
2247 //   Null_variable_info;
2248 //   UninitializedThis_variable_info;
2249 //   Object_variable_info;
2250 //   Uninitialized_variable_info;
2251 // }
2252 //
2253 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2254        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2255        u1 frame_type, TRAPS) {
2256 
2257   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2258   u1 tag = *stackmap_p_ref;
2259   stackmap_p_ref++;
2260 
2261   switch (tag) {
2262   // Top_variable_info {
2263   //   u1 tag = ITEM_Top; /* 0 */
2264   // }
2265   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2266   case 0:  // fall through
2267 
2268   // Integer_variable_info {
2269   //   u1 tag = ITEM_Integer; /* 1 */
2270   // }
2271   case ITEM_Integer:  // fall through
2272 
2273   // Float_variable_info {
2274   //   u1 tag = ITEM_Float; /* 2 */
2275   // }
2276   case ITEM_Float:  // fall through
2277 
2278   // Double_variable_info {
2279   //   u1 tag = ITEM_Double; /* 3 */
2280   // }
2281   case ITEM_Double:  // fall through
2282 
2283   // Long_variable_info {
2284   //   u1 tag = ITEM_Long; /* 4 */
2285   // }
2286   case ITEM_Long:  // fall through
2287 
2288   // Null_variable_info {
2289   //   u1 tag = ITEM_Null; /* 5 */
2290   // }
2291   case ITEM_Null:  // fall through
2292 
2293   // UninitializedThis_variable_info {
2294   //   u1 tag = ITEM_UninitializedThis; /* 6 */
2295   // }
2296   case ITEM_UninitializedThis:
2297     // nothing more to do for the above tag types
2298     break;
2299 
2300   // Object_variable_info {
2301   //   u1 tag = ITEM_Object; /* 7 */
2302   //   u2 cpool_index;
2303   // }
2304   case ITEM_Object:
2305   {
2306     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2307     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2308     u2 new_cp_index = find_new_index(cpool_index);
2309     if (new_cp_index != 0) {
2310       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2311         ("mapped old cpool_index=%d", cpool_index));
2312       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2313       cpool_index = new_cp_index;
2314     }
2315     stackmap_p_ref += 2;
2316 
2317     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2318       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2319       frame_type, cpool_index));
2320   } break;
2321 
2322   // Uninitialized_variable_info {
2323   //   u1 tag = ITEM_Uninitialized; /* 8 */
2324   //   u2 offset;
2325   // }
2326   case ITEM_Uninitialized:
2327     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2328     stackmap_p_ref += 2;
2329     break;
2330 
2331   default:
2332     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2333       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2334     ShouldNotReachHere();
2335     break;
2336   } // end switch (tag)
2337 } // end rewrite_cp_refs_in_verification_type_info()
2338 
2339 
2340 // Change the constant pool associated with klass scratch_class to
2341 // scratch_cp. If shrink is true, then scratch_cp_length elements
2342 // are copied from scratch_cp to a smaller constant pool and the
2343 // smaller constant pool is associated with scratch_class.
2344 void VM_RedefineClasses::set_new_constant_pool(
2345        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2346        int scratch_cp_length, bool shrink, TRAPS) {
2347   assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
2348 
2349   if (shrink) {
2350     // scratch_cp is a merged constant pool and has enough space for a
2351     // worst case merge situation. We want to associate the minimum
2352     // sized constant pool with the klass to save space.
2353     constantPoolHandle smaller_cp(THREAD,
2354       oopFactory::new_constantPool(scratch_cp_length,
2355                                    oopDesc::IsUnsafeConc,
2356                                    THREAD));
2357     // preserve orig_length() value in the smaller copy
2358     int orig_length = scratch_cp->orig_length();
2359     assert(orig_length != 0, "sanity check");
2360     smaller_cp->set_orig_length(orig_length);
2361     scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2362     scratch_cp = smaller_cp;
2363     smaller_cp()->set_is_conc_safe(true);
2364   }
2365 
2366   // attach new constant pool to klass
2367   scratch_cp->set_pool_holder(scratch_class());
2368 
2369   // attach klass to new constant pool
2370   scratch_class->set_constants(scratch_cp());
2371 
2372   int i;  // for portability
2373 
2374   // update each field in klass to use new constant pool indices as needed
2375   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
2376     jshort cur_index = fs.name_index();
2377     jshort new_index = find_new_index(cur_index);
2378     if (new_index != 0) {
2379       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2380         ("field-name_index change: %d to %d", cur_index, new_index));
2381       fs.set_name_index(new_index);
2382     }
2383     cur_index = fs.signature_index();
2384     new_index = find_new_index(cur_index);
2385     if (new_index != 0) {
2386       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2387         ("field-signature_index change: %d to %d", cur_index, new_index));
2388       fs.set_signature_index(new_index);
2389     }
2390     cur_index = fs.initval_index();
2391     new_index = find_new_index(cur_index);
2392     if (new_index != 0) {
2393       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2394         ("field-initval_index change: %d to %d", cur_index, new_index));
2395       fs.set_initval_index(new_index);
2396     }
2397     cur_index = fs.generic_signature_index();
2398     new_index = find_new_index(cur_index);
2399     if (new_index != 0) {
2400       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2401         ("field-generic_signature change: %d to %d", cur_index, new_index));
2402       fs.set_generic_signature_index(new_index);
2403     }
2404   } // end for each field
2405 
2406   // Update constant pool indices in the inner classes info to use
2407   // new constant indices as needed. The inner classes info is a
2408   // quadruple:
2409   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2410   typeArrayOop inner_class_list = scratch_class->inner_classes();
2411   int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
2412   if (icl_length > 0) {
2413     typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
2414     for (int i = 0; i < icl_length;
2415          i += instanceKlass::inner_class_next_offset) {
2416       int cur_index = inner_class_list_h->ushort_at(i
2417                         + instanceKlass::inner_class_inner_class_info_offset);
2418       if (cur_index == 0) {
2419         continue;  // JVM spec. allows null inner class refs so skip it
2420       }
2421       int new_index = find_new_index(cur_index);
2422       if (new_index != 0) {
2423         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2424           ("inner_class_info change: %d to %d", cur_index, new_index));
2425         inner_class_list_h->ushort_at_put(i
2426           + instanceKlass::inner_class_inner_class_info_offset, new_index);
2427       }
2428       cur_index = inner_class_list_h->ushort_at(i
2429                     + instanceKlass::inner_class_outer_class_info_offset);
2430       new_index = find_new_index(cur_index);
2431       if (new_index != 0) {
2432         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2433           ("outer_class_info change: %d to %d", cur_index, new_index));
2434         inner_class_list_h->ushort_at_put(i
2435           + instanceKlass::inner_class_outer_class_info_offset, new_index);
2436       }
2437       cur_index = inner_class_list_h->ushort_at(i
2438                     + instanceKlass::inner_class_inner_name_offset);
2439       new_index = find_new_index(cur_index);
2440       if (new_index != 0) {
2441         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2442           ("inner_name change: %d to %d", cur_index, new_index));
2443         inner_class_list_h->ushort_at_put(i
2444           + instanceKlass::inner_class_inner_name_offset, new_index);
2445       }
2446     } // end for each inner class
2447   } // end if we have inner classes
2448 
2449   // Attach each method in klass to the new constant pool and update
2450   // to use new constant pool indices as needed:
2451   objArrayHandle methods(THREAD, scratch_class->methods());
2452   for (i = methods->length() - 1; i >= 0; i--) {
2453     methodHandle method(THREAD, (methodOop)methods->obj_at(i));
2454     method->set_constants(scratch_cp());
2455 
2456     int new_index = find_new_index(method->name_index());
2457     if (new_index != 0) {
2458       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2459         ("method-name_index change: %d to %d", method->name_index(),
2460         new_index));
2461       method->set_name_index(new_index);
2462     }
2463     new_index = find_new_index(method->signature_index());
2464     if (new_index != 0) {
2465       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2466         ("method-signature_index change: %d to %d",
2467         method->signature_index(), new_index));
2468       method->set_signature_index(new_index);
2469     }
2470     new_index = find_new_index(method->generic_signature_index());
2471     if (new_index != 0) {
2472       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2473         ("method-generic_signature_index change: %d to %d",
2474         method->generic_signature_index(), new_index));
2475       method->set_generic_signature_index(new_index);
2476     }
2477 
2478     // Update constant pool indices in the method's checked exception
2479     // table to use new constant indices as needed.
2480     int cext_length = method->checked_exceptions_length();
2481     if (cext_length > 0) {
2482       CheckedExceptionElement * cext_table =
2483         method->checked_exceptions_start();
2484       for (int j = 0; j < cext_length; j++) {
2485         int cur_index = cext_table[j].class_cp_index;
2486         int new_index = find_new_index(cur_index);
2487         if (new_index != 0) {
2488           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2489             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
2490           cext_table[j].class_cp_index = (u2)new_index;
2491         }
2492       } // end for each checked exception table entry
2493     } // end if there are checked exception table entries
2494 
2495     // Update each catch type index in the method's exception table
2496     // to use new constant pool indices as needed. The exception table
2497     // holds quadruple entries of the form:
2498     //   (beg_bci, end_bci, handler_bci, klass_index)
2499     const int beg_bci_offset     = 0;
2500     const int end_bci_offset     = 1;
2501     const int handler_bci_offset = 2;
2502     const int klass_index_offset = 3;
2503     const int entry_size         = 4;
2504 
2505     typeArrayHandle ex_table (THREAD, method->exception_table());
2506     int ext_length = ex_table->length();
2507     assert(ext_length % entry_size == 0, "exception table format has changed");
2508 
2509     for (int j = 0; j < ext_length; j += entry_size) {
2510       int cur_index = ex_table->int_at(j + klass_index_offset);
2511       int new_index = find_new_index(cur_index);
2512       if (new_index != 0) {
2513         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2514           ("ext-klass_index change: %d to %d", cur_index, new_index));
2515         ex_table->int_at_put(j + klass_index_offset, new_index);
2516       }
2517     } // end for each exception table entry
2518 
2519     // Update constant pool indices in the method's local variable
2520     // table to use new constant indices as needed. The local variable
2521     // table hold sextuple entries of the form:
2522     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2523     int lvt_length = method->localvariable_table_length();
2524     if (lvt_length > 0) {
2525       LocalVariableTableElement * lv_table =
2526         method->localvariable_table_start();
2527       for (int j = 0; j < lvt_length; j++) {
2528         int cur_index = lv_table[j].name_cp_index;
2529         int new_index = find_new_index(cur_index);
2530         if (new_index != 0) {
2531           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2532             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2533           lv_table[j].name_cp_index = (u2)new_index;
2534         }
2535         cur_index = lv_table[j].descriptor_cp_index;
2536         new_index = find_new_index(cur_index);
2537         if (new_index != 0) {
2538           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2539             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2540             new_index));
2541           lv_table[j].descriptor_cp_index = (u2)new_index;
2542         }
2543         cur_index = lv_table[j].signature_cp_index;
2544         new_index = find_new_index(cur_index);
2545         if (new_index != 0) {
2546           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2547             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2548           lv_table[j].signature_cp_index = (u2)new_index;
2549         }
2550       } // end for each local variable table entry
2551     } // end if there are local variable table entries
2552 
2553     rewrite_cp_refs_in_stack_map_table(method, THREAD);
2554   } // end for each method
2555   assert(scratch_cp()->is_conc_safe(), "Just checking");
2556 } // end set_new_constant_pool()
2557 
2558 
2559 // Unevolving classes may point to methods of the_class directly
2560 // from their constant pool caches, itables, and/or vtables. We
2561 // use the SystemDictionary::classes_do() facility and this helper
2562 // to fix up these pointers.
2563 //
2564 // Note: We currently don't support updating the vtable in
2565 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2566 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
2567        oop initiating_loader, TRAPS) {
2568   Klass *k = k_oop->klass_part();
2569   if (k->oop_is_instance()) {
2570     HandleMark hm(THREAD);
2571     instanceKlass *ik = (instanceKlass *) k;
2572 
2573     // HotSpot specific optimization! HotSpot does not currently
2574     // support delegation from the bootstrap class loader to a
2575     // user-defined class loader. This means that if the bootstrap
2576     // class loader is the initiating class loader, then it will also
2577     // be the defining class loader. This also means that classes
2578     // loaded by the bootstrap class loader cannot refer to classes
2579     // loaded by a user-defined class loader. Note: a user-defined
2580     // class loader can delegate to the bootstrap class loader.
2581     //
2582     // If the current class being redefined has a user-defined class
2583     // loader as its defining class loader, then we can skip all
2584     // classes loaded by the bootstrap class loader.
2585     bool is_user_defined =
2586            instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2587     if (is_user_defined && ik->class_loader() == NULL) {
2588       return;
2589     }
2590 
2591     // This is a very busy routine. We don't want too much tracing
2592     // printed out.
2593     bool trace_name_printed = false;
2594 
2595     // Very noisy: only enable this call if you are trying to determine
2596     // that a specific class gets found by this routine.
2597     // RC_TRACE macro has an embedded ResourceMark
2598     // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2599     //   ("adjust check: name=%s", ik->external_name()));
2600     // trace_name_printed = true;
2601 
2602     // Fix the vtable embedded in the_class and subclasses of the_class,
2603     // if one exists. We discard scratch_class and we don't keep an
2604     // instanceKlass around to hold obsolete methods so we don't have
2605     // any other instanceKlass embedded vtables to update. The vtable
2606     // holds the methodOops for virtual (but not final) methods.
2607     if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2608       // ik->vtable() creates a wrapper object; rm cleans it up
2609       ResourceMark rm(THREAD);
2610       ik->vtable()->adjust_method_entries(_matching_old_methods,
2611                                           _matching_new_methods,
2612                                           _matching_methods_length,
2613                                           &trace_name_printed);
2614     }
2615 
2616     // If the current class has an itable and we are either redefining an
2617     // interface or if the current class is a subclass of the_class, then
2618     // we potentially have to fix the itable. If we are redefining an
2619     // interface, then we have to call adjust_method_entries() for
2620     // every instanceKlass that has an itable since there isn't a
2621     // subclass relationship between an interface and an instanceKlass.
2622     if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
2623         || ik->is_subclass_of(_the_class_oop))) {
2624       // ik->itable() creates a wrapper object; rm cleans it up
2625       ResourceMark rm(THREAD);
2626       ik->itable()->adjust_method_entries(_matching_old_methods,
2627                                           _matching_new_methods,
2628                                           _matching_methods_length,
2629                                           &trace_name_printed);
2630     }
2631 
2632     // The constant pools in other classes (other_cp) can refer to
2633     // methods in the_class. We have to update method information in
2634     // other_cp's cache. If other_cp has a previous version, then we
2635     // have to repeat the process for each previous version. The
2636     // constant pool cache holds the methodOops for non-virtual
2637     // methods and for virtual, final methods.
2638     //
2639     // Special case: if the current class is the_class, then new_cp
2640     // has already been attached to the_class and old_cp has already
2641     // been added as a previous version. The new_cp doesn't have any
2642     // cached references to old methods so it doesn't need to be
2643     // updated. We can simply start with the previous version(s) in
2644     // that case.
2645     constantPoolHandle other_cp;
2646     constantPoolCacheOop cp_cache;
2647 
2648     if (k_oop != _the_class_oop) {
2649       // this klass' constant pool cache may need adjustment
2650       other_cp = constantPoolHandle(ik->constants());
2651       cp_cache = other_cp->cache();
2652       if (cp_cache != NULL) {
2653         cp_cache->adjust_method_entries(_matching_old_methods,
2654                                         _matching_new_methods,
2655                                         _matching_methods_length,
2656                                         &trace_name_printed);
2657       }
2658     }
2659     {
2660       ResourceMark rm(THREAD);
2661       // PreviousVersionInfo objects returned via PreviousVersionWalker
2662       // contain a GrowableArray of handles. We have to clean up the
2663       // GrowableArray _after_ the PreviousVersionWalker destructor
2664       // has destroyed the handles.
2665       {
2666         // the previous versions' constant pool caches may need adjustment
2667         PreviousVersionWalker pvw(ik);
2668         for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2669              pv_info != NULL; pv_info = pvw.next_previous_version()) {
2670           other_cp = pv_info->prev_constant_pool_handle();
2671           cp_cache = other_cp->cache();
2672           if (cp_cache != NULL) {
2673             cp_cache->adjust_method_entries(_matching_old_methods,
2674                                             _matching_new_methods,
2675                                             _matching_methods_length,
2676                                             &trace_name_printed);
2677           }
2678         }
2679       } // pvw is cleaned up
2680     } // rm is cleaned up
2681   }
2682 }
2683 
2684 void VM_RedefineClasses::update_jmethod_ids() {
2685   for (int j = 0; j < _matching_methods_length; ++j) {
2686     methodOop old_method = _matching_old_methods[j];
2687     jmethodID jmid = old_method->find_jmethod_id_or_null();
2688     if (jmid != NULL) {
2689       // There is a jmethodID, change it to point to the new method
2690       methodHandle new_method_h(_matching_new_methods[j]);
2691       JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
2692       assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2693              "should be replaced");
2694     }
2695   }
2696 }
2697 
2698 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2699        BitMap *emcp_methods, int * emcp_method_count_p) {
2700   *emcp_method_count_p = 0;
2701   int obsolete_count = 0;
2702   int old_index = 0;
2703   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2704     methodOop old_method = _matching_old_methods[j];
2705     methodOop new_method = _matching_new_methods[j];
2706     methodOop old_array_method;
2707 
2708     // Maintain an old_index into the _old_methods array by skipping
2709     // deleted methods
2710     while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
2711                                                             != old_method) {
2712       ++old_index;
2713     }
2714 
2715     if (MethodComparator::methods_EMCP(old_method, new_method)) {
2716       // The EMCP definition from JSR-163 requires the bytecodes to be
2717       // the same with the exception of constant pool indices which may
2718       // differ. However, the constants referred to by those indices
2719       // must be the same.
2720       //
2721       // We use methods_EMCP() for comparison since constant pool
2722       // merging can remove duplicate constant pool entries that were
2723       // present in the old method and removed from the rewritten new
2724       // method. A faster binary comparison function would consider the
2725       // old and new methods to be different when they are actually
2726       // EMCP.
2727       //
2728       // The old and new methods are EMCP and you would think that we
2729       // could get rid of one of them here and now and save some space.
2730       // However, the concept of EMCP only considers the bytecodes and
2731       // the constant pool entries in the comparison. Other things,
2732       // e.g., the line number table (LNT) or the local variable table
2733       // (LVT) don't count in the comparison. So the new (and EMCP)
2734       // method can have a new LNT that we need so we can't just
2735       // overwrite the new method with the old method.
2736       //
2737       // When this routine is called, we have already attached the new
2738       // methods to the_class so the old methods are effectively
2739       // overwritten. However, if an old method is still executing,
2740       // then the old method cannot be collected until sometime after
2741       // the old method call has returned. So the overwriting of old
2742       // methods by new methods will save us space except for those
2743       // (hopefully few) old methods that are still executing.
2744       //
2745       // A method refers to a constMethodOop and this presents another
2746       // possible avenue to space savings. The constMethodOop in the
2747       // new method contains possibly new attributes (LNT, LVT, etc).
2748       // At first glance, it seems possible to save space by replacing
2749       // the constMethodOop in the old method with the constMethodOop
2750       // from the new method. The old and new methods would share the
2751       // same constMethodOop and we would save the space occupied by
2752       // the old constMethodOop. However, the constMethodOop contains
2753       // a back reference to the containing method. Sharing the
2754       // constMethodOop between two methods could lead to confusion in
2755       // the code that uses the back reference. This would lead to
2756       // brittle code that could be broken in non-obvious ways now or
2757       // in the future.
2758       //
2759       // Another possibility is to copy the constMethodOop from the new
2760       // method to the old method and then overwrite the new method with
2761       // the old method. Since the constMethodOop contains the bytecodes
2762       // for the method embedded in the oop, this option would change
2763       // the bytecodes out from under any threads executing the old
2764       // method and make the thread's bcp invalid. Since EMCP requires
2765       // that the bytecodes be the same modulo constant pool indices, it
2766       // is straight forward to compute the correct new bcp in the new
2767       // constMethodOop from the old bcp in the old constMethodOop. The
2768       // time consuming part would be searching all the frames in all
2769       // of the threads to find all of the calls to the old method.
2770       //
2771       // It looks like we will have to live with the limited savings
2772       // that we get from effectively overwriting the old methods
2773       // when the new methods are attached to the_class.
2774 
2775       // track which methods are EMCP for add_previous_version() call
2776       emcp_methods->set_bit(old_index);
2777       (*emcp_method_count_p)++;
2778 
2779       // An EMCP method is _not_ obsolete. An obsolete method has a
2780       // different jmethodID than the current method. An EMCP method
2781       // has the same jmethodID as the current method. Having the
2782       // same jmethodID for all EMCP versions of a method allows for
2783       // a consistent view of the EMCP methods regardless of which
2784       // EMCP method you happen to have in hand. For example, a
2785       // breakpoint set in one EMCP method will work for all EMCP
2786       // versions of the method including the current one.
2787     } else {
2788       // mark obsolete methods as such
2789       old_method->set_is_obsolete();
2790       obsolete_count++;
2791 
2792       // obsolete methods need a unique idnum
2793       u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
2794       if (num != constMethodOopDesc::UNSET_IDNUM) {
2795 //      u2 old_num = old_method->method_idnum();
2796         old_method->set_method_idnum(num);
2797 // TO DO: attach obsolete annotations to obsolete method's new idnum
2798       }
2799       // With tracing we try not to "yack" too much. The position of
2800       // this trace assumes there are fewer obsolete methods than
2801       // EMCP methods.
2802       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2803         old_method->name()->as_C_string(),
2804         old_method->signature()->as_C_string()));
2805     }
2806     old_method->set_is_old();
2807   }
2808   for (int i = 0; i < _deleted_methods_length; ++i) {
2809     methodOop old_method = _deleted_methods[i];
2810 
2811     assert(old_method->vtable_index() < 0,
2812            "cannot delete methods with vtable entries");;
2813 
2814     // Mark all deleted methods as old and obsolete
2815     old_method->set_is_old();
2816     old_method->set_is_obsolete();
2817     ++obsolete_count;
2818     // With tracing we try not to "yack" too much. The position of
2819     // this trace assumes there are fewer obsolete methods than
2820     // EMCP methods.
2821     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2822                           old_method->name()->as_C_string(),
2823                           old_method->signature()->as_C_string()));
2824   }
2825   assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2826     "sanity check");
2827   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2828     obsolete_count));
2829 }
2830 
2831 // This internal class transfers the native function registration from old methods
2832 // to new methods.  It is designed to handle both the simple case of unchanged
2833 // native methods and the complex cases of native method prefixes being added and/or
2834 // removed.
2835 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2836 //
2837 // This class is used after the new methods have been installed in "the_class".
2838 //
2839 // So, for example, the following must be handled.  Where 'm' is a method and
2840 // a number followed by an underscore is a prefix.
2841 //
2842 //                                      Old Name    New Name
2843 // Simple transfer to new method        m       ->  m
2844 // Add prefix                           m       ->  1_m
2845 // Remove prefix                        1_m     ->  m
2846 // Simultaneous add of prefixes         m       ->  3_2_1_m
2847 // Simultaneous removal of prefixes     3_2_1_m ->  m
2848 // Simultaneous add and remove          1_m     ->  2_m
2849 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
2850 //
2851 class TransferNativeFunctionRegistration {
2852  private:
2853   instanceKlassHandle the_class;
2854   int prefix_count;
2855   char** prefixes;
2856 
2857   // Recursively search the binary tree of possibly prefixed method names.
2858   // Iteration could be used if all agents were well behaved. Full tree walk is
2859   // more resilent to agents not cleaning up intermediate methods.
2860   // Branch at each depth in the binary tree is:
2861   //    (1) without the prefix.
2862   //    (2) with the prefix.
2863   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2864   methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
2865                                      Symbol* signature) {
2866     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
2867     if (name_symbol != NULL) {
2868       methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
2869       if (method != NULL) {
2870         // Even if prefixed, intermediate methods must exist.
2871         if (method->is_native()) {
2872           // Wahoo, we found a (possibly prefixed) version of the method, return it.
2873           return method;
2874         }
2875         if (depth < prefix_count) {
2876           // Try applying further prefixes (other than this one).
2877           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2878           if (method != NULL) {
2879             return method; // found
2880           }
2881 
2882           // Try adding this prefix to the method name and see if it matches
2883           // another method name.
2884           char* prefix = prefixes[depth];
2885           size_t prefix_len = strlen(prefix);
2886           size_t trial_len = name_len + prefix_len;
2887           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2888           strcpy(trial_name_str, prefix);
2889           strcat(trial_name_str, name_str);
2890           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2891                                             signature);
2892           if (method != NULL) {
2893             // If found along this branch, it was prefixed, mark as such
2894             method->set_is_prefixed_native();
2895             return method; // found
2896           }
2897         }
2898       }
2899     }
2900     return NULL;  // This whole branch bore nothing
2901   }
2902 
2903   // Return the method name with old prefixes stripped away.
2904   char* method_name_without_prefixes(methodOop method) {
2905     Symbol* name = method->name();
2906     char* name_str = name->as_utf8();
2907 
2908     // Old prefixing may be defunct, strip prefixes, if any.
2909     for (int i = prefix_count-1; i >= 0; i--) {
2910       char* prefix = prefixes[i];
2911       size_t prefix_len = strlen(prefix);
2912       if (strncmp(prefix, name_str, prefix_len) == 0) {
2913         name_str += prefix_len;
2914       }
2915     }
2916     return name_str;
2917   }
2918 
2919   // Strip any prefixes off the old native method, then try to find a
2920   // (possibly prefixed) new native that matches it.
2921   methodOop strip_and_search_for_new_native(methodOop method) {
2922     ResourceMark rm;
2923     char* name_str = method_name_without_prefixes(method);
2924     return search_prefix_name_space(0, name_str, strlen(name_str),
2925                                     method->signature());
2926   }
2927 
2928  public:
2929 
2930   // Construct a native method transfer processor for this class.
2931   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2932     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2933 
2934     the_class = _the_class;
2935     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
2936   }
2937 
2938   // Attempt to transfer any of the old or deleted methods that are native
2939   void transfer_registrations(methodOop* old_methods, int methods_length) {
2940     for (int j = 0; j < methods_length; j++) {
2941       methodOop old_method = old_methods[j];
2942 
2943       if (old_method->is_native() && old_method->has_native_function()) {
2944         methodOop new_method = strip_and_search_for_new_native(old_method);
2945         if (new_method != NULL) {
2946           // Actually set the native function in the new method.
2947           // Redefine does not send events (except CFLH), certainly not this
2948           // behind the scenes re-registration.
2949           new_method->set_native_function(old_method->native_function(),
2950                               !methodOopDesc::native_bind_event_is_interesting);
2951         }
2952       }
2953     }
2954   }
2955 };
2956 
2957 // Don't lose the association between a native method and its JNI function.
2958 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
2959   TransferNativeFunctionRegistration transfer(the_class);
2960   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
2961   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
2962 }
2963 
2964 // Deoptimize all compiled code that depends on this class.
2965 //
2966 // If the can_redefine_classes capability is obtained in the onload
2967 // phase then the compiler has recorded all dependencies from startup.
2968 // In that case we need only deoptimize and throw away all compiled code
2969 // that depends on the class.
2970 //
2971 // If can_redefine_classes is obtained sometime after the onload
2972 // phase then the dependency information may be incomplete. In that case
2973 // the first call to RedefineClasses causes all compiled code to be
2974 // thrown away. As can_redefine_classes has been obtained then
2975 // all future compilations will record dependencies so second and
2976 // subsequent calls to RedefineClasses need only throw away code
2977 // that depends on the class.
2978 //
2979 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
2980   assert_locked_or_safepoint(Compile_lock);
2981 
2982   // All dependencies have been recorded from startup or this is a second or
2983   // subsequent use of RedefineClasses
2984   if (JvmtiExport::all_dependencies_are_recorded()) {
2985     Universe::flush_evol_dependents_on(k_h);
2986   } else {
2987     CodeCache::mark_all_nmethods_for_deoptimization();
2988 
2989     ResourceMark rm(THREAD);
2990     DeoptimizationMarker dm;
2991 
2992     // Deoptimize all activations depending on marked nmethods
2993     Deoptimization::deoptimize_dependents();
2994 
2995     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
2996     CodeCache::make_marked_nmethods_not_entrant();
2997 
2998     // From now on we know that the dependency information is complete
2999     JvmtiExport::set_all_dependencies_are_recorded(true);
3000   }
3001 }
3002 
3003 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3004   methodOop old_method;
3005   methodOop new_method;
3006 
3007   _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3008   _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3009   _added_methods        = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
3010   _deleted_methods      = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3011 
3012   _matching_methods_length = 0;
3013   _deleted_methods_length  = 0;
3014   _added_methods_length    = 0;
3015 
3016   int nj = 0;
3017   int oj = 0;
3018   while (true) {
3019     if (oj >= _old_methods->length()) {
3020       if (nj >= _new_methods->length()) {
3021         break; // we've looked at everything, done
3022       }
3023       // New method at the end
3024       new_method = (methodOop) _new_methods->obj_at(nj);
3025       _added_methods[_added_methods_length++] = new_method;
3026       ++nj;
3027     } else if (nj >= _new_methods->length()) {
3028       // Old method, at the end, is deleted
3029       old_method = (methodOop) _old_methods->obj_at(oj);
3030       _deleted_methods[_deleted_methods_length++] = old_method;
3031       ++oj;
3032     } else {
3033       old_method = (methodOop) _old_methods->obj_at(oj);
3034       new_method = (methodOop) _new_methods->obj_at(nj);
3035       if (old_method->name() == new_method->name()) {
3036         if (old_method->signature() == new_method->signature()) {
3037           _matching_old_methods[_matching_methods_length  ] = old_method;
3038           _matching_new_methods[_matching_methods_length++] = new_method;
3039           ++nj;
3040           ++oj;
3041         } else {
3042           // added overloaded have already been moved to the end,
3043           // so this is a deleted overloaded method
3044           _deleted_methods[_deleted_methods_length++] = old_method;
3045           ++oj;
3046         }
3047       } else { // names don't match
3048         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3049           // new method
3050           _added_methods[_added_methods_length++] = new_method;
3051           ++nj;
3052         } else {
3053           // deleted method
3054           _deleted_methods[_deleted_methods_length++] = old_method;
3055           ++oj;
3056         }
3057       }
3058     }
3059   }
3060   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3061   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3062 }
3063 
3064 
3065 
3066 // Install the redefinition of a class:
3067 //    - house keeping (flushing breakpoints and caches, deoptimizing
3068 //      dependent compiled code)
3069 //    - replacing parts in the_class with parts from scratch_class
3070 //    - adding a weak reference to track the obsolete but interesting
3071 //      parts of the_class
3072 //    - adjusting constant pool caches and vtables in other classes
3073 //      that refer to methods in the_class. These adjustments use the
3074 //      SystemDictionary::classes_do() facility which only allows
3075 //      a helper method to be specified. The interesting parameters
3076 //      that we would like to pass to the helper method are saved in
3077 //      static global fields in the VM operation.
3078 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3079        instanceKlassHandle scratch_class, TRAPS) {
3080 
3081   RC_TIMER_START(_timer_rsc_phase1);
3082 
3083   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3084   klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
3085   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3086 
3087 #ifndef JVMTI_KERNEL
3088   // Remove all breakpoints in methods of this class
3089   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3090   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3091 #endif // !JVMTI_KERNEL
3092 
3093   if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3094     // We are redefining java.lang.reflect.Method. Method.invoke() is
3095     // cached and users of the cache care about each active version of
3096     // the method so we have to track this previous version.
3097     // Do this before methods get switched
3098     Universe::reflect_invoke_cache()->add_previous_version(
3099       the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3100   }
3101 
3102   // Deoptimize all compiled code that depends on this class
3103   flush_dependent_code(the_class, THREAD);
3104 
3105   _old_methods = the_class->methods();
3106   _new_methods = scratch_class->methods();
3107   _the_class_oop = the_class_oop;
3108   compute_added_deleted_matching_methods();
3109   update_jmethod_ids();
3110 
3111   // Attach new constant pool to the original klass. The original
3112   // klass still refers to the old constant pool (for now).
3113   scratch_class->constants()->set_pool_holder(the_class());
3114 
3115 #if 0
3116   // In theory, with constant pool merging in place we should be able
3117   // to save space by using the new, merged constant pool in place of
3118   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3119   // the klass version we are replacing now and any constant pool(s) in
3120   // previous versions of klass. Nice theory, doesn't work in practice.
3121   // When this code is enabled, even simple programs throw NullPointer
3122   // exceptions. I'm guessing that this is caused by some constant pool
3123   // cache difference between the new, merged constant pool and the
3124   // constant pool that was just being used by the klass. I'm keeping
3125   // this code around to archive the idea, but the code has to remain
3126   // disabled for now.
3127 
3128   // Attach each old method to the new constant pool. This can be
3129   // done here since we are past the bytecode verification and
3130   // constant pool optimization phases.
3131   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3132     methodOop method = (methodOop)_old_methods->obj_at(i);
3133     method->set_constants(scratch_class->constants());
3134   }
3135 
3136   {
3137     // walk all previous versions of the klass
3138     instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
3139     PreviousVersionWalker pvw(ik);
3140     instanceKlassHandle ikh;
3141     do {
3142       ikh = pvw.next_previous_version();
3143       if (!ikh.is_null()) {
3144         ik = ikh();
3145 
3146         // attach previous version of klass to the new constant pool
3147         ik->set_constants(scratch_class->constants());
3148 
3149         // Attach each method in the previous version of klass to the
3150         // new constant pool
3151         objArrayOop prev_methods = ik->methods();
3152         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3153           methodOop method = (methodOop)prev_methods->obj_at(i);
3154           method->set_constants(scratch_class->constants());
3155         }
3156       }
3157     } while (!ikh.is_null());
3158   }
3159 #endif
3160 
3161   // Replace methods and constantpool
3162   the_class->set_methods(_new_methods);
3163   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3164                                           // and to be able to undo operation easily.
3165 
3166   constantPoolOop old_constants = the_class->constants();
3167   the_class->set_constants(scratch_class->constants());
3168   scratch_class->set_constants(old_constants);  // See the previous comment.
3169 #if 0
3170   // We are swapping the guts of "the new class" with the guts of "the
3171   // class". Since the old constant pool has just been attached to "the
3172   // new class", it seems logical to set the pool holder in the old
3173   // constant pool also. However, doing this will change the observable
3174   // class hierarchy for any old methods that are still executing. A
3175   // method can query the identity of its "holder" and this query uses
3176   // the method's constant pool link to find the holder. The change in
3177   // holding class from "the class" to "the new class" can confuse
3178   // things.
3179   //
3180   // Setting the old constant pool's holder will also cause
3181   // verification done during vtable initialization below to fail.
3182   // During vtable initialization, the vtable's class is verified to be
3183   // a subtype of the method's holder. The vtable's class is "the
3184   // class" and the method's holder is gotten from the constant pool
3185   // link in the method itself. For "the class"'s directly implemented
3186   // methods, the method holder is "the class" itself (as gotten from
3187   // the new constant pool). The check works fine in this case. The
3188   // check also works fine for methods inherited from super classes.
3189   //
3190   // Miranda methods are a little more complicated. A miranda method is
3191   // provided by an interface when the class implementing the interface
3192   // does not provide its own method.  These interfaces are implemented
3193   // internally as an instanceKlass. These special instanceKlasses
3194   // share the constant pool of the class that "implements" the
3195   // interface. By sharing the constant pool, the method holder of a
3196   // miranda method is the class that "implements" the interface. In a
3197   // non-redefine situation, the subtype check works fine. However, if
3198   // the old constant pool's pool holder is modified, then the check
3199   // fails because there is no class hierarchy relationship between the
3200   // vtable's class and "the new class".
3201 
3202   old_constants->set_pool_holder(scratch_class());
3203 #endif
3204 
3205   // track which methods are EMCP for add_previous_version() call below
3206   BitMap emcp_methods(_old_methods->length());
3207   int emcp_method_count = 0;
3208   emcp_methods.clear();  // clears 0..(length() - 1)
3209   check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3210   transfer_old_native_function_registrations(the_class);
3211 
3212   // The class file bytes from before any retransformable agents mucked
3213   // with them was cached on the scratch class, move to the_class.
3214   // Note: we still want to do this if nothing needed caching since it
3215   // should get cleared in the_class too.
3216   if (the_class->get_cached_class_file_bytes() == 0) {
3217     // the_class doesn't have a cache yet so copy it
3218     the_class->set_cached_class_file(
3219       scratch_class->get_cached_class_file_bytes(),
3220       scratch_class->get_cached_class_file_len());
3221   }
3222 #ifndef PRODUCT
3223   else {
3224     assert(the_class->get_cached_class_file_bytes() ==
3225       scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
3226     assert(the_class->get_cached_class_file_len() ==
3227       scratch_class->get_cached_class_file_len(), "cache lens must match");
3228   }
3229 #endif
3230 
3231   // Replace inner_classes
3232   typeArrayOop old_inner_classes = the_class->inner_classes();
3233   the_class->set_inner_classes(scratch_class->inner_classes());
3234   scratch_class->set_inner_classes(old_inner_classes);
3235 
3236   // Initialize the vtable and interface table after
3237   // methods have been rewritten
3238   {
3239     ResourceMark rm(THREAD);
3240     // no exception should happen here since we explicitly
3241     // do not check loader constraints.
3242     // compare_and_normalize_class_versions has already checked:
3243     //  - classloaders unchanged, signatures unchanged
3244     //  - all instanceKlasses for redefined classes reused & contents updated
3245     the_class->vtable()->initialize_vtable(false, THREAD);
3246     the_class->itable()->initialize_itable(false, THREAD);
3247     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3248   }
3249 
3250   // Leave arrays of jmethodIDs and itable index cache unchanged
3251 
3252   // Copy the "source file name" attribute from new class version
3253   the_class->set_source_file_name(scratch_class->source_file_name());
3254 
3255   // Copy the "source debug extension" attribute from new class version
3256   the_class->set_source_debug_extension(
3257     scratch_class->source_debug_extension(),
3258     scratch_class->source_debug_extension() == NULL ? 0 :
3259     (int)strlen(scratch_class->source_debug_extension()));
3260 
3261   // Use of javac -g could be different in the old and the new
3262   if (scratch_class->access_flags().has_localvariable_table() !=
3263       the_class->access_flags().has_localvariable_table()) {
3264 
3265     AccessFlags flags = the_class->access_flags();
3266     if (scratch_class->access_flags().has_localvariable_table()) {
3267       flags.set_has_localvariable_table();
3268     } else {
3269       flags.clear_has_localvariable_table();
3270     }
3271     the_class->set_access_flags(flags);
3272   }
3273 
3274   // Replace class annotation fields values
3275   typeArrayOop old_class_annotations = the_class->class_annotations();
3276   the_class->set_class_annotations(scratch_class->class_annotations());
3277   scratch_class->set_class_annotations(old_class_annotations);
3278 
3279   // Replace fields annotation fields values
3280   objArrayOop old_fields_annotations = the_class->fields_annotations();
3281   the_class->set_fields_annotations(scratch_class->fields_annotations());
3282   scratch_class->set_fields_annotations(old_fields_annotations);
3283 
3284   // Replace methods annotation fields values
3285   objArrayOop old_methods_annotations = the_class->methods_annotations();
3286   the_class->set_methods_annotations(scratch_class->methods_annotations());
3287   scratch_class->set_methods_annotations(old_methods_annotations);
3288 
3289   // Replace methods parameter annotation fields values
3290   objArrayOop old_methods_parameter_annotations =
3291     the_class->methods_parameter_annotations();
3292   the_class->set_methods_parameter_annotations(
3293     scratch_class->methods_parameter_annotations());
3294   scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
3295 
3296   // Replace methods default annotation fields values
3297   objArrayOop old_methods_default_annotations =
3298     the_class->methods_default_annotations();
3299   the_class->set_methods_default_annotations(
3300     scratch_class->methods_default_annotations());
3301   scratch_class->set_methods_default_annotations(old_methods_default_annotations);
3302 
3303   // Replace minor version number of class file
3304   u2 old_minor_version = the_class->minor_version();
3305   the_class->set_minor_version(scratch_class->minor_version());
3306   scratch_class->set_minor_version(old_minor_version);
3307 
3308   // Replace major version number of class file
3309   u2 old_major_version = the_class->major_version();
3310   the_class->set_major_version(scratch_class->major_version());
3311   scratch_class->set_major_version(old_major_version);
3312 
3313   // Replace CP indexes for class and name+type of enclosing method
3314   u2 old_class_idx  = the_class->enclosing_method_class_index();
3315   u2 old_method_idx = the_class->enclosing_method_method_index();
3316   the_class->set_enclosing_method_indices(
3317     scratch_class->enclosing_method_class_index(),
3318     scratch_class->enclosing_method_method_index());
3319   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3320 
3321   // keep track of previous versions of this class
3322   the_class->add_previous_version(scratch_class, &emcp_methods,
3323     emcp_method_count);
3324 
3325   RC_TIMER_STOP(_timer_rsc_phase1);
3326   RC_TIMER_START(_timer_rsc_phase2);
3327 
3328   // Adjust constantpool caches and vtables for all classes
3329   // that reference methods of the evolved class.
3330   SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3331 
3332   if (the_class->oop_map_cache() != NULL) {
3333     // Flush references to any obsolete methods from the oop map cache
3334     // so that obsolete methods are not pinned.
3335     the_class->oop_map_cache()->flush_obsolete_entries();
3336   }
3337 
3338   // increment the classRedefinedCount field in the_class and in any
3339   // direct and indirect subclasses of the_class
3340   increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
3341 
3342   // RC_TRACE macro has an embedded ResourceMark
3343   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3344     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3345     the_class->external_name(),
3346     java_lang_Class::classRedefinedCount(the_class_mirror),
3347     os::available_memory() >> 10));
3348 
3349   RC_TIMER_STOP(_timer_rsc_phase2);
3350 } // end redefine_single_class()
3351 
3352 
3353 // Increment the classRedefinedCount field in the specific instanceKlass
3354 // and in all direct and indirect subclasses.
3355 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
3356   oop class_mirror = ik->java_mirror();
3357   klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
3358   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3359   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3360 
3361   if (class_oop != _the_class_oop) {
3362     // _the_class_oop count is printed at end of redefine_single_class()
3363     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3364       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3365   }
3366 
3367   for (Klass *subk = ik->subklass(); subk != NULL;
3368        subk = subk->next_sibling()) {
3369     if (subk->oop_is_instance()) {
3370       // Only update instanceKlasses
3371       instanceKlass *subik = (instanceKlass*)subk;
3372       // recursively do subclasses of the current subclass
3373       increment_class_counter(subik, THREAD);
3374     }
3375   }
3376 }
3377 

3378 void VM_RedefineClasses::check_class(klassOop k_oop,
3379        oop initiating_loader, TRAPS) {
3380   Klass *k = k_oop->klass_part();
3381   if (k->oop_is_instance()) {
3382     HandleMark hm(THREAD);
3383     instanceKlass *ik = (instanceKlass *) k;
3384     bool no_old_methods = true;  // be optimistic

3385     ResourceMark rm(THREAD);
3386 
3387     // a vtable should never contain old or obsolete methods
3388     if (ik->vtable_length() > 0 &&
3389         !ik->vtable()->check_no_old_or_obsolete_entries()) {
3390       if (RC_TRACE_ENABLED(0x00004000)) {
3391         RC_TRACE_WITH_THREAD(0x00004000, THREAD,
3392           ("klassVtable::check_no_old_or_obsolete_entries failure"
3393            " -- OLD or OBSOLETE method found -- class: %s",
3394            ik->signature_name()));
3395         ik->vtable()->dump_vtable();
3396       }
3397       no_old_methods = false;
3398     }
3399 
3400     // an itable should never contain old or obsolete methods
3401     if (ik->itable_length() > 0 &&
3402         !ik->itable()->check_no_old_or_obsolete_entries()) {
3403       if (RC_TRACE_ENABLED(0x00004000)) {
3404         RC_TRACE_WITH_THREAD(0x00004000, THREAD,
3405           ("klassItable::check_no_old_or_obsolete_entries failure"
3406            " -- OLD or OBSOLETE method found -- class: %s",
3407            ik->signature_name()));
3408         ik->itable()->dump_itable();
3409       }
3410       no_old_methods = false;
3411     }
3412 
3413     // the constant pool cache should never contain old or obsolete methods
3414     if (ik->constants() != NULL &&
3415         ik->constants()->cache() != NULL &&
3416         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
3417       if (RC_TRACE_ENABLED(0x00004000)) {
3418         RC_TRACE_WITH_THREAD(0x00004000, THREAD,
3419           ("cp-cache::check_no_old_or_obsolete_entries failure"
3420            " -- OLD or OBSOLETE method found -- class: %s",
3421            ik->signature_name()));
3422         ik->constants()->cache()->dump_cache();
3423       }
3424       no_old_methods = false;
3425     }
3426 
3427     if (!no_old_methods) {
3428       if (RC_TRACE_ENABLED(0x00004000)) {
3429         dump_methods();
3430       } else {
3431         tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
3432           "to see more info about the following guarantee() failure.");
3433       }
3434       guarantee(false, "OLD and/or OBSOLETE method(s) found");
3435     }
3436   }
3437 }
3438 
3439 void VM_RedefineClasses::dump_methods() {
3440   int j;
3441   RC_TRACE(0x00004000, ("_old_methods --"));
3442   for (j = 0; j < _old_methods->length(); ++j) {
3443     methodOop m = (methodOop) _old_methods->obj_at(j);
3444     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
3445     m->access_flags().print_on(tty);
3446     tty->print(" --  ");
3447     m->print_name(tty);
3448     tty->cr();
3449   }
3450   RC_TRACE(0x00004000, ("_new_methods --"));
3451   for (j = 0; j < _new_methods->length(); ++j) {
3452     methodOop m = (methodOop) _new_methods->obj_at(j);
3453     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
3454     m->access_flags().print_on(tty);
3455     tty->print(" --  ");
3456     m->print_name(tty);
3457     tty->cr();
3458   }
3459   RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
3460   for (j = 0; j < _matching_methods_length; ++j) {
3461     methodOop m = _matching_old_methods[j];
3462     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
3463     m->access_flags().print_on(tty);
3464     tty->print(" --  ");
3465     m->print_name(tty);
3466     tty->cr();
3467     m = _matching_new_methods[j];
3468     RC_TRACE_NO_CR(0x00004000, ("      (%5d)  ", m->vtable_index()));
3469     m->access_flags().print_on(tty);
3470     tty->cr();
3471   }
3472   RC_TRACE(0x00004000, ("_deleted_methods --"));
3473   for (j = 0; j < _deleted_methods_length; ++j) {
3474     methodOop m = _deleted_methods[j];
3475     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
3476     m->access_flags().print_on(tty);
3477     tty->print(" --  ");
3478     m->print_name(tty);
3479     tty->cr();
3480   }
3481   RC_TRACE(0x00004000, ("_added_methods --"));
3482   for (j = 0; j < _added_methods_length; ++j) {
3483     methodOop m = _added_methods[j];
3484     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
3485     m->access_flags().print_on(tty);
3486     tty->print(" --  ");
3487     m->print_name(tty);
3488     tty->cr();
3489   }
3490 }

--- EOF ---