1 /*
   2  * Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/metadataOnStackMark.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/verifier.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "compiler/compileBroker.hpp"
  31 #include "interpreter/oopMapCache.hpp"
  32 #include "interpreter/rewriter.hpp"
  33 #include "memory/gcLocker.hpp"
  34 #include "memory/metadataFactory.hpp"
  35 #include "memory/metaspaceShared.hpp"
  36 #include "memory/universe.inline.hpp"
  37 #include "oops/fieldStreams.hpp"
  38 #include "oops/klassVtable.hpp"
  39 #include "prims/jvmtiImpl.hpp"
  40 #include "prims/jvmtiRedefineClasses.hpp"
  41 #include "prims/methodComparator.hpp"
  42 #include "runtime/deoptimization.hpp"
  43 #include "runtime/relocator.hpp"
  44 #include "utilities/bitMap.inline.hpp"
  45 
  46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  47 
  48 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
  49 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
  50 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
  51 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
  52 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
  53 Method**  VM_RedefineClasses::_added_methods        = NULL;
  54 int         VM_RedefineClasses::_matching_methods_length = 0;
  55 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  56 int         VM_RedefineClasses::_added_methods_length    = 0;
  57 Klass*      VM_RedefineClasses::_the_class_oop = NULL;
  58 
  59 
  60 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  61                                        const jvmtiClassDefinition *class_defs,
  62                                        JvmtiClassLoadKind class_load_kind) {
  63   _class_count = class_count;
  64   _class_defs = class_defs;
  65   _class_load_kind = class_load_kind;
  66   _res = JVMTI_ERROR_NONE;
  67 }
  68 
  69 bool VM_RedefineClasses::doit_prologue() {
  70   if (_class_count == 0) {
  71     _res = JVMTI_ERROR_NONE;
  72     return false;
  73   }
  74   if (_class_defs == NULL) {
  75     _res = JVMTI_ERROR_NULL_POINTER;
  76     return false;
  77   }
  78   for (int i = 0; i < _class_count; i++) {
  79     if (_class_defs[i].klass == NULL) {
  80       _res = JVMTI_ERROR_INVALID_CLASS;
  81       return false;
  82     }
  83     if (_class_defs[i].class_byte_count == 0) {
  84       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
  85       return false;
  86     }
  87     if (_class_defs[i].class_bytes == NULL) {
  88       _res = JVMTI_ERROR_NULL_POINTER;
  89       return false;
  90     }
  91   }
  92 
  93   // Start timer after all the sanity checks; not quite accurate, but
  94   // better than adding a bunch of stop() calls.
  95   RC_TIMER_START(_timer_vm_op_prologue);
  96 
  97   // We first load new class versions in the prologue, because somewhere down the
  98   // call chain it is required that the current thread is a Java thread.
  99   _res = load_new_class_versions(Thread::current());
 100   if (_res != JVMTI_ERROR_NONE) {
 101     // free any successfully created classes, since none are redefined
 102     for (int i = 0; i < _class_count; i++) {
 103       if (_scratch_classes[i] != NULL) {
 104         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 105         // Free the memory for this class at class unloading time.  Not before
 106         // because CMS might think this is still live.
 107         cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
 108       }
 109     }
 110     // Free os::malloc allocated memory in load_new_class_version.
 111     os::free(_scratch_classes);
 112     RC_TIMER_STOP(_timer_vm_op_prologue);
 113     return false;
 114   }
 115 
 116   RC_TIMER_STOP(_timer_vm_op_prologue);
 117   return true;
 118 }
 119 
 120 void VM_RedefineClasses::doit() {
 121   Thread *thread = Thread::current();
 122 
 123   if (UseSharedSpaces) {
 124     // Sharing is enabled so we remap the shared readonly space to
 125     // shared readwrite, private just in case we need to redefine
 126     // a shared class. We do the remap during the doit() phase of
 127     // the safepoint to be safer.
 128     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
 129       RC_TRACE_WITH_THREAD(0x00000001, thread,
 130         ("failed to remap shared readonly space to readwrite, private"));
 131       _res = JVMTI_ERROR_INTERNAL;
 132       return;
 133     }
 134   }
 135 
 136   // Mark methods seen on stack and everywhere else so old methods are not
 137   // cleaned up if they're on the stack.
 138   MetadataOnStackMark md_on_stack(true);
 139   HandleMark hm(thread);   // make sure any handles created are deleted
 140                            // before the stack walk again.
 141 
 142   for (int i = 0; i < _class_count; i++) {
 143     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 144     ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 145     // Free the memory for this class at class unloading time.  Not before
 146     // because CMS might think this is still live.
 147     cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
 148     _scratch_classes[i] = NULL;
 149   }
 150 
 151   // Clean out MethodData pointing to old Method*
 152   MethodDataCleaner clean_weak_method_links;
 153   ClassLoaderDataGraph::classes_do(&clean_weak_method_links);
 154 
 155   // Disable any dependent concurrent compilations
 156   SystemDictionary::notice_modification();
 157 
 158   // Set flag indicating that some invariants are no longer true.
 159   // See jvmtiExport.hpp for detailed explanation.
 160   JvmtiExport::set_has_redefined_a_class();
 161 
 162   // check_class() is optionally called for product bits, but is
 163   // always called for non-product bits.
 164 #ifdef PRODUCT
 165   if (RC_TRACE_ENABLED(0x00004000)) {
 166 #endif
 167     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
 168     CheckClass check_class(thread);
 169     ClassLoaderDataGraph::classes_do(&check_class);
 170 #ifdef PRODUCT
 171   }
 172 #endif
 173 }
 174 
 175 void VM_RedefineClasses::doit_epilogue() {
 176   // Free os::malloc allocated memory.
 177   os::free(_scratch_classes);
 178 
 179   if (RC_TRACE_ENABLED(0x00000004)) {
 180     // Used to have separate timers for "doit" and "all", but the timer
 181     // overhead skewed the measurements.
 182     jlong doit_time = _timer_rsc_phase1.milliseconds() +
 183                       _timer_rsc_phase2.milliseconds();
 184     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 185 
 186     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
 187       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
 188       _timer_vm_op_prologue.milliseconds(), doit_time));
 189     RC_TRACE(0x00000004,
 190       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
 191        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
 192   }
 193 }
 194 
 195 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 196   // classes for primitives cannot be redefined
 197   if (java_lang_Class::is_primitive(klass_mirror)) {
 198     return false;
 199   }
 200   Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
 201   // classes for arrays cannot be redefined
 202   if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
 203     return false;
 204   }
 205   return true;
 206 }
 207 
 208 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 209 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 210 // direct CP entries, there is just the current entry to append. For
 211 // indirect and double-indirect CP entries, there are zero or more
 212 // referenced CP entries along with the current entry to append.
 213 // Indirect and double-indirect CP entries are handled by recursive
 214 // calls to append_entry() as needed. The referenced CP entries are
 215 // always appended to *merge_cp_p before the referee CP entry. These
 216 // referenced CP entries may already exist in *merge_cp_p in which case
 217 // there is nothing extra to append and only the current entry is
 218 // appended.
 219 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
 220        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 221        TRAPS) {
 222 
 223   // append is different depending on entry tag type
 224   switch (scratch_cp->tag_at(scratch_i).value()) {
 225 
 226     // The old verifier is implemented outside the VM. It loads classes,
 227     // but does not resolve constant pool entries directly so we never
 228     // see Class entries here with the old verifier. Similarly the old
 229     // verifier does not like Class entries in the input constant pool.
 230     // The split-verifier is implemented in the VM so it can optionally
 231     // and directly resolve constant pool entries to load classes. The
 232     // split-verifier can accept either Class entries or UnresolvedClass
 233     // entries in the input constant pool. We revert the appended copy
 234     // back to UnresolvedClass so that either verifier will be happy
 235     // with the constant pool entry.
 236     case JVM_CONSTANT_Class:
 237     {
 238       // revert the copy to JVM_CONSTANT_UnresolvedClass
 239       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
 240         scratch_cp->klass_name_at(scratch_i));
 241 
 242       if (scratch_i != *merge_cp_length_p) {
 243         // The new entry in *merge_cp_p is at a different index than
 244         // the new entry in scratch_cp so we need to map the index values.
 245         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 246       }
 247       (*merge_cp_length_p)++;
 248     } break;
 249 
 250     // these are direct CP entries so they can be directly appended,
 251     // but double and long take two constant pool entries
 252     case JVM_CONSTANT_Double:  // fall through
 253     case JVM_CONSTANT_Long:
 254     {
 255       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 256         THREAD);
 257 
 258       if (scratch_i != *merge_cp_length_p) {
 259         // The new entry in *merge_cp_p is at a different index than
 260         // the new entry in scratch_cp so we need to map the index values.
 261         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 262       }
 263       (*merge_cp_length_p) += 2;
 264     } break;
 265 
 266     // these are direct CP entries so they can be directly appended
 267     case JVM_CONSTANT_Float:   // fall through
 268     case JVM_CONSTANT_Integer: // fall through
 269     case JVM_CONSTANT_Utf8:    // fall through
 270 
 271     // This was an indirect CP entry, but it has been changed into
 272     // Symbol*s so this entry can be directly appended.
 273     case JVM_CONSTANT_String:      // fall through
 274 
 275     // These were indirect CP entries, but they have been changed into
 276     // Symbol*s so these entries can be directly appended.
 277     case JVM_CONSTANT_UnresolvedClass:  // fall through
 278     {
 279       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 280         THREAD);
 281 
 282       if (scratch_i != *merge_cp_length_p) {
 283         // The new entry in *merge_cp_p is at a different index than
 284         // the new entry in scratch_cp so we need to map the index values.
 285         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 286       }
 287       (*merge_cp_length_p)++;
 288     } break;
 289 
 290     // this is an indirect CP entry so it needs special handling
 291     case JVM_CONSTANT_NameAndType:
 292     {
 293       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 294       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
 295                                                          merge_cp_length_p, THREAD);
 296 
 297       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 298       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
 299                                                               merge_cp_p, merge_cp_length_p,
 300                                                               THREAD);
 301 
 302       // If the referenced entries already exist in *merge_cp_p, then
 303       // both new_name_ref_i and new_signature_ref_i will both be 0.
 304       // In that case, all we are appending is the current entry.
 305       if (new_name_ref_i != name_ref_i) {
 306         RC_TRACE(0x00080000,
 307           ("NameAndType entry@%d name_ref_index change: %d to %d",
 308           *merge_cp_length_p, name_ref_i, new_name_ref_i));
 309       }
 310       if (new_signature_ref_i != signature_ref_i) {
 311         RC_TRACE(0x00080000,
 312           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 313           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
 314       }
 315 
 316       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 317         new_name_ref_i, new_signature_ref_i);
 318       if (scratch_i != *merge_cp_length_p) {
 319         // The new entry in *merge_cp_p is at a different index than
 320         // the new entry in scratch_cp so we need to map the index values.
 321         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 322       }
 323       (*merge_cp_length_p)++;
 324     } break;
 325 
 326     // this is a double-indirect CP entry so it needs special handling
 327     case JVM_CONSTANT_Fieldref:           // fall through
 328     case JVM_CONSTANT_InterfaceMethodref: // fall through
 329     case JVM_CONSTANT_Methodref:
 330     {
 331       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 332       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
 333                                                           merge_cp_p, merge_cp_length_p, THREAD);
 334 
 335       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 336       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
 337                                                           merge_cp_p, merge_cp_length_p, THREAD);
 338 
 339       const char *entry_name;
 340       switch (scratch_cp->tag_at(scratch_i).value()) {
 341       case JVM_CONSTANT_Fieldref:
 342         entry_name = "Fieldref";
 343         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 344           new_name_and_type_ref_i);
 345         break;
 346       case JVM_CONSTANT_InterfaceMethodref:
 347         entry_name = "IFMethodref";
 348         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 349           new_klass_ref_i, new_name_and_type_ref_i);
 350         break;
 351       case JVM_CONSTANT_Methodref:
 352         entry_name = "Methodref";
 353         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 354           new_name_and_type_ref_i);
 355         break;
 356       default:
 357         guarantee(false, "bad switch");
 358         break;
 359       }
 360 
 361       if (klass_ref_i != new_klass_ref_i) {
 362         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
 363           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
 364       }
 365       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 366         RC_TRACE(0x00080000,
 367           ("%s entry@%d name_and_type_index changed: %d to %d",
 368           entry_name, *merge_cp_length_p, name_and_type_ref_i,
 369           new_name_and_type_ref_i));
 370       }
 371 
 372       if (scratch_i != *merge_cp_length_p) {
 373         // The new entry in *merge_cp_p is at a different index than
 374         // the new entry in scratch_cp so we need to map the index values.
 375         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 376       }
 377       (*merge_cp_length_p)++;
 378     } break;
 379 
 380     // this is an indirect CP entry so it needs special handling
 381     case JVM_CONSTANT_MethodType:
 382     {
 383       int ref_i = scratch_cp->method_type_index_at(scratch_i);
 384       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 385                                                     merge_cp_length_p, THREAD);
 386       if (new_ref_i != ref_i) {
 387         RC_TRACE(0x00080000,
 388                  ("MethodType entry@%d ref_index change: %d to %d",
 389                   *merge_cp_length_p, ref_i, new_ref_i));
 390       }
 391       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
 392       if (scratch_i != *merge_cp_length_p) {
 393         // The new entry in *merge_cp_p is at a different index than
 394         // the new entry in scratch_cp so we need to map the index values.
 395         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 396       }
 397       (*merge_cp_length_p)++;
 398     } break;
 399 
 400     // this is an indirect CP entry so it needs special handling
 401     case JVM_CONSTANT_MethodHandle:
 402     {
 403       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
 404       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
 405       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 406                                                     merge_cp_length_p, THREAD);
 407       if (new_ref_i != ref_i) {
 408         RC_TRACE(0x00080000,
 409                  ("MethodHandle entry@%d ref_index change: %d to %d",
 410                   *merge_cp_length_p, ref_i, new_ref_i));
 411       }
 412       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
 413       if (scratch_i != *merge_cp_length_p) {
 414         // The new entry in *merge_cp_p is at a different index than
 415         // the new entry in scratch_cp so we need to map the index values.
 416         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 417       }
 418       (*merge_cp_length_p)++;
 419     } break;
 420 
 421     // this is an indirect CP entry so it needs special handling
 422     case JVM_CONSTANT_InvokeDynamic:
 423     {
 424       // Index of the bootstrap specifier in the operands array
 425       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
 426       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
 427                                             merge_cp_length_p, THREAD);
 428       // The bootstrap method NameAndType_info index
 429       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
 430       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 431                                                     merge_cp_length_p, THREAD);
 432       if (new_bs_i != old_bs_i) {
 433         RC_TRACE(0x00080000,
 434                  ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
 435                   *merge_cp_length_p, old_bs_i, new_bs_i));
 436       }
 437       if (new_ref_i != old_ref_i) {
 438         RC_TRACE(0x00080000,
 439                  ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
 440                   *merge_cp_length_p, old_ref_i, new_ref_i));
 441       }
 442 
 443       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
 444       if (scratch_i != *merge_cp_length_p) {
 445         // The new entry in *merge_cp_p is at a different index than
 446         // the new entry in scratch_cp so we need to map the index values.
 447         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 448       }
 449       (*merge_cp_length_p)++;
 450     } break;
 451 
 452     // At this stage, Class or UnresolvedClass could be here, but not
 453     // ClassIndex
 454     case JVM_CONSTANT_ClassIndex: // fall through
 455 
 456     // Invalid is used as the tag for the second constant pool entry
 457     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 458     // not be seen by itself.
 459     case JVM_CONSTANT_Invalid: // fall through
 460 
 461     // At this stage, String could be here, but not StringIndex
 462     case JVM_CONSTANT_StringIndex: // fall through
 463 
 464     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 465     // here
 466     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 467 
 468     default:
 469     {
 470       // leave a breadcrumb
 471       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 472       ShouldNotReachHere();
 473     } break;
 474   } // end switch tag value
 475 } // end append_entry()
 476 
 477 
 478 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
 479       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 480 
 481   int new_ref_i = ref_i;
 482   bool match = (ref_i < *merge_cp_length_p) &&
 483                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
 484 
 485   if (!match) {
 486     // forward reference in *merge_cp_p or not a direct match
 487     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
 488     if (found_i != 0) {
 489       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
 490       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
 491       new_ref_i = found_i;
 492       map_index(scratch_cp, ref_i, found_i);
 493     } else {
 494       // no match found so we have to append this entry to *merge_cp_p
 495       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
 496       // The above call to append_entry() can only append one entry
 497       // so the post call query of *merge_cp_length_p is only for
 498       // the sake of consistency.
 499       new_ref_i = *merge_cp_length_p - 1;
 500     }
 501   }
 502 
 503   return new_ref_i;
 504 } // end find_or_append_indirect_entry()
 505 
 506 
 507 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
 508 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
 509 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
 510 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
 511        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 512 
 513   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
 514   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 515                                                 merge_cp_length_p, THREAD);
 516   if (new_ref_i != old_ref_i) {
 517     RC_TRACE(0x00080000,
 518              ("operands entry@%d bootstrap method ref_index change: %d to %d",
 519               _operands_cur_length, old_ref_i, new_ref_i));
 520   }
 521 
 522   Array<u2>* merge_ops = (*merge_cp_p)->operands();
 523   int new_bs_i = _operands_cur_length;
 524   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
 525   // However, the operand_offset_at(0) was set in the extend_operands() call.
 526   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
 527                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
 528   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
 529 
 530   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
 531   merge_ops->at_put(new_base++, new_ref_i);
 532   merge_ops->at_put(new_base++, argc);
 533 
 534   for (int i = 0; i < argc; i++) {
 535     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
 536     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
 537                                                       merge_cp_length_p, THREAD);
 538     merge_ops->at_put(new_base++, new_arg_ref_i);
 539     if (new_arg_ref_i != old_arg_ref_i) {
 540       RC_TRACE(0x00080000,
 541                ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
 542                 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));
 543     }
 544   }
 545   if (old_bs_i != _operands_cur_length) {
 546     // The bootstrap specifier in *merge_cp_p is at a different index than
 547     // that in scratch_cp so we need to map the index values.
 548     map_operand_index(old_bs_i, new_bs_i);
 549   }
 550   _operands_cur_length++;
 551 } // end append_operand()
 552 
 553 
 554 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
 555       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 556 
 557   int new_bs_i = old_bs_i; // bootstrap specifier index
 558   bool match = (old_bs_i < _operands_cur_length) &&
 559                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
 560 
 561   if (!match) {
 562     // forward reference in *merge_cp_p or not a direct match
 563     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
 564                                                     _operands_cur_length, THREAD);
 565     if (found_i != -1) {
 566       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
 567       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
 568       new_bs_i = found_i;
 569       map_operand_index(old_bs_i, found_i);
 570     } else {
 571       // no match found so we have to append this bootstrap specifier to *merge_cp_p
 572       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
 573       new_bs_i = _operands_cur_length - 1;
 574     }
 575   }
 576   return new_bs_i;
 577 } // end find_or_append_operand()
 578 
 579 
 580 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
 581   if (merge_cp->operands() == NULL) {
 582     return;
 583   }
 584   // Shrink the merge_cp operands
 585   merge_cp->shrink_operands(_operands_cur_length, CHECK);
 586 
 587   if (RC_TRACE_ENABLED(0x00040000)) {
 588     // don't want to loop unless we are tracing
 589     int count = 0;
 590     for (int i = 1; i < _operands_index_map_p->length(); i++) {
 591       int value = _operands_index_map_p->at(i);
 592       if (value != -1) {
 593         RC_TRACE_WITH_THREAD(0x00040000, THREAD,
 594           ("operands_index_map[%d]: old=%d new=%d", count, i, value));
 595         count++;
 596       }
 597     }
 598   }
 599   // Clean-up
 600   _operands_index_map_p = NULL;
 601   _operands_cur_length = 0;
 602   _operands_index_map_count = 0;
 603 } // end finalize_operands_merge()
 604 
 605 
 606 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 607              instanceKlassHandle the_class,
 608              instanceKlassHandle scratch_class) {
 609   int i;
 610 
 611   // Check superclasses, or rather their names, since superclasses themselves can be
 612   // requested to replace.
 613   // Check for NULL superclass first since this might be java.lang.Object
 614   if (the_class->super() != scratch_class->super() &&
 615       (the_class->super() == NULL || scratch_class->super() == NULL ||
 616        the_class->super()->name() !=
 617        scratch_class->super()->name())) {
 618     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 619   }
 620 
 621   // Check if the number, names and order of directly implemented interfaces are the same.
 622   // I think in principle we should just check if the sets of names of directly implemented
 623   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 624   // .java file, also changes in .class file) should not matter. However, comparing sets is
 625   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 626   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 627   // rely on it somewhere.
 628   Array<Klass*>* k_interfaces = the_class->local_interfaces();
 629   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
 630   int n_intfs = k_interfaces->length();
 631   if (n_intfs != k_new_interfaces->length()) {
 632     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 633   }
 634   for (i = 0; i < n_intfs; i++) {
 635     if (k_interfaces->at(i)->name() !=
 636         k_new_interfaces->at(i)->name()) {
 637       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 638     }
 639   }
 640 
 641   // Check whether class is in the error init state.
 642   if (the_class->is_in_error_state()) {
 643     // TBD #5057930: special error code is needed in 1.6
 644     return JVMTI_ERROR_INVALID_CLASS;
 645   }
 646 
 647   // Check whether class modifiers are the same.
 648   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 649   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 650   if (old_flags != new_flags) {
 651     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 652   }
 653 
 654   // Check if the number, names, types and order of fields declared in these classes
 655   // are the same.
 656   JavaFieldStream old_fs(the_class);
 657   JavaFieldStream new_fs(scratch_class);
 658   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 659     // access
 660     old_flags = old_fs.access_flags().as_short();
 661     new_flags = new_fs.access_flags().as_short();
 662     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 663       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 664     }
 665     // offset
 666     if (old_fs.offset() != new_fs.offset()) {
 667       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 668     }
 669     // name and signature
 670     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 671     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 672     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 673     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 674     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
 675       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 676     }
 677   }
 678 
 679   // If both streams aren't done then we have a differing number of
 680   // fields.
 681   if (!old_fs.done() || !new_fs.done()) {
 682     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 683   }
 684 
 685   // Do a parallel walk through the old and new methods. Detect
 686   // cases where they match (exist in both), have been added in
 687   // the new methods, or have been deleted (exist only in the
 688   // old methods).  The class file parser places methods in order
 689   // by method name, but does not order overloaded methods by
 690   // signature.  In order to determine what fate befell the methods,
 691   // this code places the overloaded new methods that have matching
 692   // old methods in the same order as the old methods and places
 693   // new overloaded methods at the end of overloaded methods of
 694   // that name. The code for this order normalization is adapted
 695   // from the algorithm used in InstanceKlass::find_method().
 696   // Since we are swapping out of order entries as we find them,
 697   // we only have to search forward through the overloaded methods.
 698   // Methods which are added and have the same name as an existing
 699   // method (but different signature) will be put at the end of
 700   // the methods with that name, and the name mismatch code will
 701   // handle them.
 702   Array<Method*>* k_old_methods(the_class->methods());
 703   Array<Method*>* k_new_methods(scratch_class->methods());
 704   int n_old_methods = k_old_methods->length();
 705   int n_new_methods = k_new_methods->length();
 706   Thread* thread = Thread::current();
 707 
 708   int ni = 0;
 709   int oi = 0;
 710   while (true) {
 711     Method* k_old_method;
 712     Method* k_new_method;
 713     enum { matched, added, deleted, undetermined } method_was = undetermined;
 714 
 715     if (oi >= n_old_methods) {
 716       if (ni >= n_new_methods) {
 717         break; // we've looked at everything, done
 718       }
 719       // New method at the end
 720       k_new_method = k_new_methods->at(ni);
 721       method_was = added;
 722     } else if (ni >= n_new_methods) {
 723       // Old method, at the end, is deleted
 724       k_old_method = k_old_methods->at(oi);
 725       method_was = deleted;
 726     } else {
 727       // There are more methods in both the old and new lists
 728       k_old_method = k_old_methods->at(oi);
 729       k_new_method = k_new_methods->at(ni);
 730       if (k_old_method->name() != k_new_method->name()) {
 731         // Methods are sorted by method name, so a mismatch means added
 732         // or deleted
 733         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 734           method_was = added;
 735         } else {
 736           method_was = deleted;
 737         }
 738       } else if (k_old_method->signature() == k_new_method->signature()) {
 739         // Both the name and signature match
 740         method_was = matched;
 741       } else {
 742         // The name matches, but the signature doesn't, which means we have to
 743         // search forward through the new overloaded methods.
 744         int nj;  // outside the loop for post-loop check
 745         for (nj = ni + 1; nj < n_new_methods; nj++) {
 746           Method* m = k_new_methods->at(nj);
 747           if (k_old_method->name() != m->name()) {
 748             // reached another method name so no more overloaded methods
 749             method_was = deleted;
 750             break;
 751           }
 752           if (k_old_method->signature() == m->signature()) {
 753             // found a match so swap the methods
 754             k_new_methods->at_put(ni, m);
 755             k_new_methods->at_put(nj, k_new_method);
 756             k_new_method = m;
 757             method_was = matched;
 758             break;
 759           }
 760         }
 761 
 762         if (nj >= n_new_methods) {
 763           // reached the end without a match; so method was deleted
 764           method_was = deleted;
 765         }
 766       }
 767     }
 768 
 769     switch (method_was) {
 770     case matched:
 771       // methods match, be sure modifiers do too
 772       old_flags = (jushort) k_old_method->access_flags().get_flags();
 773       new_flags = (jushort) k_new_method->access_flags().get_flags();
 774       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 775         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 776       }
 777       {
 778         u2 new_num = k_new_method->method_idnum();
 779         u2 old_num = k_old_method->method_idnum();
 780         if (new_num != old_num) {
 781           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
 782           if (idnum_owner != NULL) {
 783             // There is already a method assigned this idnum -- switch them
 784             // Take current and original idnum from the new_method
 785             idnum_owner->set_method_idnum(new_num);
 786             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 787           }
 788           // Take current and original idnum from the old_method
 789           k_new_method->set_method_idnum(old_num);
 790           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
 791           if (thread->has_pending_exception()) {
 792             return JVMTI_ERROR_OUT_OF_MEMORY;
 793           }
 794         }
 795       }
 796       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
 797                             k_new_method->name_and_sig_as_C_string(), ni,
 798                             k_old_method->name_and_sig_as_C_string(), oi));
 799       // advance to next pair of methods
 800       ++oi;
 801       ++ni;
 802       break;
 803     case added:
 804       // method added, see if it is OK
 805       new_flags = (jushort) k_new_method->access_flags().get_flags();
 806       if ((new_flags & JVM_ACC_PRIVATE) == 0
 807            // hack: private should be treated as final, but alas
 808           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 809          ) {
 810         // new methods must be private
 811         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 812       }
 813       {
 814         u2 num = the_class->next_method_idnum();
 815         if (num == ConstMethod::UNSET_IDNUM) {
 816           // cannot add any more methods
 817           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 818         }
 819         u2 new_num = k_new_method->method_idnum();
 820         Method* idnum_owner = scratch_class->method_with_idnum(num);
 821         if (idnum_owner != NULL) {
 822           // There is already a method assigned this idnum -- switch them
 823           // Take current and original idnum from the new_method
 824           idnum_owner->set_method_idnum(new_num);
 825           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 826         }
 827         k_new_method->set_method_idnum(num);
 828         k_new_method->set_orig_method_idnum(num);
 829         if (thread->has_pending_exception()) {
 830           return JVMTI_ERROR_OUT_OF_MEMORY;
 831         }
 832       }
 833       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
 834                             k_new_method->name_and_sig_as_C_string(), ni));
 835       ++ni; // advance to next new method
 836       break;
 837     case deleted:
 838       // method deleted, see if it is OK
 839       old_flags = (jushort) k_old_method->access_flags().get_flags();
 840       if ((old_flags & JVM_ACC_PRIVATE) == 0
 841            // hack: private should be treated as final, but alas
 842           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 843          ) {
 844         // deleted methods must be private
 845         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 846       }
 847       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
 848                             k_old_method->name_and_sig_as_C_string(), oi));
 849       ++oi; // advance to next old method
 850       break;
 851     default:
 852       ShouldNotReachHere();
 853     }
 854   }
 855 
 856   return JVMTI_ERROR_NONE;
 857 }
 858 
 859 
 860 // Find new constant pool index value for old constant pool index value
 861 // by seaching the index map. Returns zero (0) if there is no mapped
 862 // value for the old constant pool index.
 863 int VM_RedefineClasses::find_new_index(int old_index) {
 864   if (_index_map_count == 0) {
 865     // map is empty so nothing can be found
 866     return 0;
 867   }
 868 
 869   if (old_index < 1 || old_index >= _index_map_p->length()) {
 870     // The old_index is out of range so it is not mapped. This should
 871     // not happen in regular constant pool merging use, but it can
 872     // happen if a corrupt annotation is processed.
 873     return 0;
 874   }
 875 
 876   int value = _index_map_p->at(old_index);
 877   if (value == -1) {
 878     // the old_index is not mapped
 879     return 0;
 880   }
 881 
 882   return value;
 883 } // end find_new_index()
 884 
 885 
 886 // Find new bootstrap specifier index value for old bootstrap specifier index
 887 // value by seaching the index map. Returns unused index (-1) if there is
 888 // no mapped value for the old bootstrap specifier index.
 889 int VM_RedefineClasses::find_new_operand_index(int old_index) {
 890   if (_operands_index_map_count == 0) {
 891     // map is empty so nothing can be found
 892     return -1;
 893   }
 894 
 895   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
 896     // The old_index is out of range so it is not mapped.
 897     // This should not happen in regular constant pool merging use.
 898     return -1;
 899   }
 900 
 901   int value = _operands_index_map_p->at(old_index);
 902   if (value == -1) {
 903     // the old_index is not mapped
 904     return -1;
 905   }
 906 
 907   return value;
 908 } // end find_new_operand_index()
 909 
 910 
 911 // Returns true if the current mismatch is due to a resolved/unresolved
 912 // class pair. Otherwise, returns false.
 913 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
 914        int index1, constantPoolHandle cp2, int index2) {
 915 
 916   jbyte t1 = cp1->tag_at(index1).value();
 917   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 918     return false;  // wrong entry type; not our special case
 919   }
 920 
 921   jbyte t2 = cp2->tag_at(index2).value();
 922   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 923     return false;  // wrong entry type; not our special case
 924   }
 925 
 926   if (t1 == t2) {
 927     return false;  // not a mismatch; not our special case
 928   }
 929 
 930   char *s1 = cp1->klass_name_at(index1)->as_C_string();
 931   char *s2 = cp2->klass_name_at(index2)->as_C_string();
 932   if (strcmp(s1, s2) != 0) {
 933     return false;  // strings don't match; not our special case
 934   }
 935 
 936   return true;  // made it through the gauntlet; this is our special case
 937 } // end is_unresolved_class_mismatch()
 938 
 939 
 940 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
 941 
 942   // For consistency allocate memory using os::malloc wrapper.
 943   _scratch_classes = (Klass**)
 944     os::malloc(sizeof(Klass*) * _class_count, mtClass);
 945   if (_scratch_classes == NULL) {
 946     return JVMTI_ERROR_OUT_OF_MEMORY;
 947   }
 948   // Zero initialize the _scratch_classes array.
 949   for (int i = 0; i < _class_count; i++) {
 950     _scratch_classes[i] = NULL;
 951   }
 952 
 953   ResourceMark rm(THREAD);
 954 
 955   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
 956   // state can only be NULL if the current thread is exiting which
 957   // should not happen since we're trying to do a RedefineClasses
 958   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
 959   for (int i = 0; i < _class_count; i++) {
 960     // Create HandleMark so that any handles created while loading new class
 961     // versions are deleted. Constant pools are deallocated while merging
 962     // constant pools
 963     HandleMark hm(THREAD);
 964 
 965     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 966     // classes for primitives cannot be redefined
 967     if (!is_modifiable_class(mirror)) {
 968       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
 969     }
 970     Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
 971     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
 972     Symbol*  the_class_sym = the_class->name();
 973 
 974     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 975     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
 976       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
 977       the_class->external_name(), _class_load_kind,
 978       os::available_memory() >> 10));
 979 
 980     ClassFileStream st((u1*) _class_defs[i].class_bytes,
 981       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
 982 
 983     // Parse the stream.
 984     Handle the_class_loader(THREAD, the_class->class_loader());
 985     Handle protection_domain(THREAD, the_class->protection_domain());
 986     // Set redefined class handle in JvmtiThreadState class.
 987     // This redefined class is sent to agent event handler for class file
 988     // load hook event.
 989     state->set_class_being_redefined(&the_class, _class_load_kind);
 990 
 991     Klass* k = SystemDictionary::parse_stream(the_class_sym,
 992                                                 the_class_loader,
 993                                                 protection_domain,
 994                                                 &st,
 995                                                 THREAD);
 996     // Clear class_being_redefined just to be sure.
 997     state->clear_class_being_redefined();
 998 
 999     // TODO: if this is retransform, and nothing changed we can skip it
1000 
1001     instanceKlassHandle scratch_class (THREAD, k);
1002 
1003     // Need to clean up allocated InstanceKlass if there's an error so assign
1004     // the result here. Caller deallocates all the scratch classes in case of
1005     // an error.
1006     _scratch_classes[i] = k;
1007 
1008     if (HAS_PENDING_EXCEPTION) {
1009       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1010       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1011       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
1012         ex_name->as_C_string()));
1013       CLEAR_PENDING_EXCEPTION;
1014 
1015       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1016         return JVMTI_ERROR_UNSUPPORTED_VERSION;
1017       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1018         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1019       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1020         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1021       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1022         // The message will be "XXX (wrong name: YYY)"
1023         return JVMTI_ERROR_NAMES_DONT_MATCH;
1024       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1025         return JVMTI_ERROR_OUT_OF_MEMORY;
1026       } else {  // Just in case more exceptions can be thrown..
1027         return JVMTI_ERROR_FAILS_VERIFICATION;
1028       }
1029     }
1030 
1031     // Ensure class is linked before redefine
1032     if (!the_class->is_linked()) {
1033       the_class->link_class(THREAD);
1034       if (HAS_PENDING_EXCEPTION) {
1035         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1036         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1037         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
1038           ex_name->as_C_string()));
1039         CLEAR_PENDING_EXCEPTION;
1040         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1041           return JVMTI_ERROR_OUT_OF_MEMORY;
1042         } else {
1043           return JVMTI_ERROR_INTERNAL;
1044         }
1045       }
1046     }
1047 
1048     // Do the validity checks in compare_and_normalize_class_versions()
1049     // before verifying the byte codes. By doing these checks first, we
1050     // limit the number of functions that require redirection from
1051     // the_class to scratch_class. In particular, we don't have to
1052     // modify JNI GetSuperclass() and thus won't change its performance.
1053     jvmtiError res = compare_and_normalize_class_versions(the_class,
1054                        scratch_class);
1055     if (res != JVMTI_ERROR_NONE) {
1056       return res;
1057     }
1058 
1059     // verify what the caller passed us
1060     {
1061       // The bug 6214132 caused the verification to fail.
1062       // Information about the_class and scratch_class is temporarily
1063       // recorded into jvmtiThreadState. This data is used to redirect
1064       // the_class to scratch_class in the JVM_* functions called by the
1065       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1066       // description.
1067       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1068       Verifier::verify(
1069         scratch_class, Verifier::ThrowException, true, THREAD);
1070     }
1071 
1072     if (HAS_PENDING_EXCEPTION) {
1073       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1074       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1075       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1076         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
1077       CLEAR_PENDING_EXCEPTION;
1078       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1079         return JVMTI_ERROR_OUT_OF_MEMORY;
1080       } else {
1081         // tell the caller the bytecodes are bad
1082         return JVMTI_ERROR_FAILS_VERIFICATION;
1083       }
1084     }
1085 
1086     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1087     if (HAS_PENDING_EXCEPTION) {
1088       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1089       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1090       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1091         ("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()));
1092       CLEAR_PENDING_EXCEPTION;
1093       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1094         return JVMTI_ERROR_OUT_OF_MEMORY;
1095       } else {
1096         return JVMTI_ERROR_INTERNAL;
1097       }
1098     }
1099 
1100     if (VerifyMergedCPBytecodes) {
1101       // verify what we have done during constant pool merging
1102       {
1103         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1104         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1105       }
1106 
1107       if (HAS_PENDING_EXCEPTION) {
1108         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1109         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1110         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1111           ("verify_byte_codes post merge-CP exception: '%s'",
1112           ex_name->as_C_string()));
1113         CLEAR_PENDING_EXCEPTION;
1114         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1115           return JVMTI_ERROR_OUT_OF_MEMORY;
1116         } else {
1117           // tell the caller that constant pool merging screwed up
1118           return JVMTI_ERROR_INTERNAL;
1119         }
1120       }
1121     }
1122 
1123     Rewriter::rewrite(scratch_class, THREAD);
1124     if (!HAS_PENDING_EXCEPTION) {
1125       scratch_class->link_methods(THREAD);
1126     }
1127     if (HAS_PENDING_EXCEPTION) {
1128       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1129       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1130       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1131         ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()));
1132       CLEAR_PENDING_EXCEPTION;
1133       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1134         return JVMTI_ERROR_OUT_OF_MEMORY;
1135       } else {
1136         return JVMTI_ERROR_INTERNAL;
1137       }
1138     }
1139 
1140     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1141     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1142       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1143       the_class->external_name(), os::available_memory() >> 10));
1144   }
1145 
1146   return JVMTI_ERROR_NONE;
1147 }
1148 
1149 
1150 // Map old_index to new_index as needed. scratch_cp is only needed
1151 // for RC_TRACE() calls.
1152 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1153        int old_index, int new_index) {
1154   if (find_new_index(old_index) != 0) {
1155     // old_index is already mapped
1156     return;
1157   }
1158 
1159   if (old_index == new_index) {
1160     // no mapping is needed
1161     return;
1162   }
1163 
1164   _index_map_p->at_put(old_index, new_index);
1165   _index_map_count++;
1166 
1167   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1168     scratch_cp->tag_at(old_index).value(), old_index, new_index));
1169 } // end map_index()
1170 
1171 
1172 // Map old_index to new_index as needed.
1173 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1174   if (find_new_operand_index(old_index) != -1) {
1175     // old_index is already mapped
1176     return;
1177   }
1178 
1179   if (old_index == new_index) {
1180     // no mapping is needed
1181     return;
1182   }
1183 
1184   _operands_index_map_p->at_put(old_index, new_index);
1185   _operands_index_map_count++;
1186 
1187   RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
1188 } // end map_index()
1189 
1190 
1191 // Merge old_cp and scratch_cp and return the results of the merge via
1192 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1193 // merge_cp_length_p. The entries in old_cp occupy the same locations
1194 // in *merge_cp_p. Also creates a map of indices from entries in
1195 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1196 // entries are only created for entries in scratch_cp that occupy a
1197 // different location in *merged_cp_p.
1198 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1199        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1200        int *merge_cp_length_p, TRAPS) {
1201 
1202   if (merge_cp_p == NULL) {
1203     assert(false, "caller must provide scratch constantPool");
1204     return false; // robustness
1205   }
1206   if (merge_cp_length_p == NULL) {
1207     assert(false, "caller must provide scratch CP length");
1208     return false; // robustness
1209   }
1210   // Worst case we need old_cp->length() + scratch_cp()->length(),
1211   // but the caller might be smart so make sure we have at least
1212   // the minimum.
1213   if ((*merge_cp_p)->length() < old_cp->length()) {
1214     assert(false, "merge area too small");
1215     return false; // robustness
1216   }
1217 
1218   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1219     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1220     scratch_cp->length()));
1221 
1222   {
1223     // Pass 0:
1224     // The old_cp is copied to *merge_cp_p; this means that any code
1225     // using old_cp does not have to change. This work looks like a
1226     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1227     // handle one special case:
1228     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1229     // This will make verification happy.
1230 
1231     int old_i;  // index into old_cp
1232 
1233     // index zero (0) is not used in constantPools
1234     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1235       // leave debugging crumb
1236       jbyte old_tag = old_cp->tag_at(old_i).value();
1237       switch (old_tag) {
1238       case JVM_CONSTANT_Class:
1239       case JVM_CONSTANT_UnresolvedClass:
1240         // revert the copy to JVM_CONSTANT_UnresolvedClass
1241         // May be resolving while calling this so do the same for
1242         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1243         (*merge_cp_p)->unresolved_klass_at_put(old_i,
1244           old_cp->klass_name_at(old_i));
1245         break;
1246 
1247       case JVM_CONSTANT_Double:
1248       case JVM_CONSTANT_Long:
1249         // just copy the entry to *merge_cp_p, but double and long take
1250         // two constant pool entries
1251         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1252         old_i++;
1253         break;
1254 
1255       default:
1256         // just copy the entry to *merge_cp_p
1257         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1258         break;
1259       }
1260     } // end for each old_cp entry
1261 
1262     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1263     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1264 
1265     // We don't need to sanity check that *merge_cp_length_p is within
1266     // *merge_cp_p bounds since we have the minimum on-entry check above.
1267     (*merge_cp_length_p) = old_i;
1268   }
1269 
1270   // merge_cp_len should be the same as old_cp->length() at this point
1271   // so this trace message is really a "warm-and-breathing" message.
1272   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1273     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1274 
1275   int scratch_i;  // index into scratch_cp
1276   {
1277     // Pass 1a:
1278     // Compare scratch_cp entries to the old_cp entries that we have
1279     // already copied to *merge_cp_p. In this pass, we are eliminating
1280     // exact duplicates (matching entry at same index) so we only
1281     // compare entries in the common indice range.
1282     int increment = 1;
1283     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1284     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1285       switch (scratch_cp->tag_at(scratch_i).value()) {
1286       case JVM_CONSTANT_Double:
1287       case JVM_CONSTANT_Long:
1288         // double and long take two constant pool entries
1289         increment = 2;
1290         break;
1291 
1292       default:
1293         increment = 1;
1294         break;
1295       }
1296 
1297       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1298         scratch_i, CHECK_0);
1299       if (match) {
1300         // found a match at the same index so nothing more to do
1301         continue;
1302       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1303                                               *merge_cp_p, scratch_i)) {
1304         // The mismatch in compare_entry_to() above is because of a
1305         // resolved versus unresolved class entry at the same index
1306         // with the same string value. Since Pass 0 reverted any
1307         // class entries to unresolved class entries in *merge_cp_p,
1308         // we go with the unresolved class entry.
1309         continue;
1310       }
1311 
1312       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1313         CHECK_0);
1314       if (found_i != 0) {
1315         guarantee(found_i != scratch_i,
1316           "compare_entry_to() and find_matching_entry() do not agree");
1317 
1318         // Found a matching entry somewhere else in *merge_cp_p so
1319         // just need a mapping entry.
1320         map_index(scratch_cp, scratch_i, found_i);
1321         continue;
1322       }
1323 
1324       // The find_matching_entry() call above could fail to find a match
1325       // due to a resolved versus unresolved class or string entry situation
1326       // like we solved above with the is_unresolved_*_mismatch() calls.
1327       // However, we would have to call is_unresolved_*_mismatch() over
1328       // all of *merge_cp_p (potentially) and that doesn't seem to be
1329       // worth the time.
1330 
1331       // No match found so we have to append this entry and any unique
1332       // referenced entries to *merge_cp_p.
1333       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1334         CHECK_0);
1335     }
1336   }
1337 
1338   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1339     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1340     *merge_cp_length_p, scratch_i, _index_map_count));
1341 
1342   if (scratch_i < scratch_cp->length()) {
1343     // Pass 1b:
1344     // old_cp is smaller than scratch_cp so there are entries in
1345     // scratch_cp that we have not yet processed. We take care of
1346     // those now.
1347     int increment = 1;
1348     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1349       switch (scratch_cp->tag_at(scratch_i).value()) {
1350       case JVM_CONSTANT_Double:
1351       case JVM_CONSTANT_Long:
1352         // double and long take two constant pool entries
1353         increment = 2;
1354         break;
1355 
1356       default:
1357         increment = 1;
1358         break;
1359       }
1360 
1361       int found_i =
1362         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1363       if (found_i != 0) {
1364         // Found a matching entry somewhere else in *merge_cp_p so
1365         // just need a mapping entry.
1366         map_index(scratch_cp, scratch_i, found_i);
1367         continue;
1368       }
1369 
1370       // No match found so we have to append this entry and any unique
1371       // referenced entries to *merge_cp_p.
1372       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1373         CHECK_0);
1374     }
1375 
1376     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1377       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1378       *merge_cp_length_p, scratch_i, _index_map_count));
1379   }
1380   finalize_operands_merge(*merge_cp_p, THREAD);
1381 
1382   return true;
1383 } // end merge_constant_pools()
1384 
1385 
1386 // Scoped object to clean up the constant pool(s) created for merging
1387 class MergeCPCleaner {
1388   ClassLoaderData*   _loader_data;
1389   ConstantPool*      _cp;
1390   ConstantPool*      _scratch_cp;
1391  public:
1392   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1393                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1394   ~MergeCPCleaner() {
1395     _loader_data->add_to_deallocate_list(_cp);
1396     if (_scratch_cp != NULL) {
1397       _loader_data->add_to_deallocate_list(_scratch_cp);
1398     }
1399   }
1400   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1401 };
1402 
1403 // Merge constant pools between the_class and scratch_class and
1404 // potentially rewrite bytecodes in scratch_class to use the merged
1405 // constant pool.
1406 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1407              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1408              TRAPS) {
1409   // worst case merged constant pool length is old and new combined
1410   int merge_cp_length = the_class->constants()->length()
1411         + scratch_class->constants()->length();
1412 
1413   // Constant pools are not easily reused so we allocate a new one
1414   // each time.
1415   // merge_cp is created unsafe for concurrent GC processing.  It
1416   // should be marked safe before discarding it. Even though
1417   // garbage,  if it crosses a card boundary, it may be scanned
1418   // in order to find the start of the first complete object on the card.
1419   ClassLoaderData* loader_data = the_class->class_loader_data();
1420   ConstantPool* merge_cp_oop =
1421     ConstantPool::allocate(loader_data,
1422                            merge_cp_length,
1423                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1424   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1425 
1426   HandleMark hm(THREAD);  // make sure handles are cleared before
1427                           // MergeCPCleaner clears out merge_cp_oop
1428   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1429 
1430   // Get constants() from the old class because it could have been rewritten
1431   // while we were at a safepoint allocating a new constant pool.
1432   constantPoolHandle old_cp(THREAD, the_class->constants());
1433   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1434 
1435   // If the length changed, the class was redefined out from under us. Return
1436   // an error.
1437   if (merge_cp_length != the_class->constants()->length()
1438          + scratch_class->constants()->length()) {
1439     return JVMTI_ERROR_INTERNAL;
1440   }
1441 
1442   // Update the version number of the constant pool
1443   merge_cp->increment_and_save_version(old_cp->version());
1444 
1445   ResourceMark rm(THREAD);
1446   _index_map_count = 0;
1447   _index_map_p = new intArray(scratch_cp->length(), -1);
1448 
1449   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1450   _operands_index_map_count = 0;
1451   _operands_index_map_p = new intArray(
1452     ConstantPool::operand_array_length(scratch_cp->operands()), -1);
1453 
1454   // reference to the cp holder is needed for copy_operands()
1455   merge_cp->set_pool_holder(scratch_class());
1456   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1457                   &merge_cp_length, THREAD);
1458   merge_cp->set_pool_holder(NULL);
1459 
1460   if (!result) {
1461     // The merge can fail due to memory allocation failure or due
1462     // to robustness checks.
1463     return JVMTI_ERROR_INTERNAL;
1464   }
1465 
1466   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1467     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1468 
1469   if (_index_map_count == 0) {
1470     // there is nothing to map between the new and merged constant pools
1471 
1472     if (old_cp->length() == scratch_cp->length()) {
1473       // The old and new constant pools are the same length and the
1474       // index map is empty. This means that the three constant pools
1475       // are equivalent (but not the same). Unfortunately, the new
1476       // constant pool has not gone through link resolution nor have
1477       // the new class bytecodes gone through constant pool cache
1478       // rewriting so we can't use the old constant pool with the new
1479       // class.
1480 
1481       // toss the merged constant pool at return
1482     } else if (old_cp->length() < scratch_cp->length()) {
1483       // The old constant pool has fewer entries than the new constant
1484       // pool and the index map is empty. This means the new constant
1485       // pool is a superset of the old constant pool. However, the old
1486       // class bytecodes have already gone through constant pool cache
1487       // rewriting so we can't use the new constant pool with the old
1488       // class.
1489 
1490       // toss the merged constant pool at return
1491     } else {
1492       // The old constant pool has more entries than the new constant
1493       // pool and the index map is empty. This means that both the old
1494       // and merged constant pools are supersets of the new constant
1495       // pool.
1496 
1497       // Replace the new constant pool with a shrunken copy of the
1498       // merged constant pool
1499       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1500                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1501       // The new constant pool replaces scratch_cp so have cleaner clean it up.
1502       // It can't be cleaned up while there are handles to it.
1503       cp_cleaner.add_scratch_cp(scratch_cp());
1504     }
1505   } else {
1506     if (RC_TRACE_ENABLED(0x00040000)) {
1507       // don't want to loop unless we are tracing
1508       int count = 0;
1509       for (int i = 1; i < _index_map_p->length(); i++) {
1510         int value = _index_map_p->at(i);
1511 
1512         if (value != -1) {
1513           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1514             ("index_map[%d]: old=%d new=%d", count, i, value));
1515           count++;
1516         }
1517       }
1518     }
1519 
1520     // We have entries mapped between the new and merged constant pools
1521     // so we have to rewrite some constant pool references.
1522     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1523       return JVMTI_ERROR_INTERNAL;
1524     }
1525 
1526     // Replace the new constant pool with a shrunken copy of the
1527     // merged constant pool so now the rewritten bytecodes have
1528     // valid references; the previous new constant pool will get
1529     // GCed.
1530     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1531                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1532     // The new constant pool replaces scratch_cp so have cleaner clean it up.
1533     // It can't be cleaned up while there are handles to it.
1534     cp_cleaner.add_scratch_cp(scratch_cp());
1535   }
1536 
1537   return JVMTI_ERROR_NONE;
1538 } // end merge_cp_and_rewrite()
1539 
1540 
1541 // Rewrite constant pool references in klass scratch_class.
1542 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1543        TRAPS) {
1544 
1545   // rewrite constant pool references in the methods:
1546   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1547     // propagate failure back to caller
1548     return false;
1549   }
1550 
1551   // rewrite constant pool references in the class_annotations:
1552   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1553     // propagate failure back to caller
1554     return false;
1555   }
1556 
1557   // rewrite constant pool references in the fields_annotations:
1558   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1559     // propagate failure back to caller
1560     return false;
1561   }
1562 
1563   // rewrite constant pool references in the methods_annotations:
1564   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1565     // propagate failure back to caller
1566     return false;
1567   }
1568 
1569   // rewrite constant pool references in the methods_parameter_annotations:
1570   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1571          THREAD)) {
1572     // propagate failure back to caller
1573     return false;
1574   }
1575 
1576   // rewrite constant pool references in the methods_default_annotations:
1577   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1578          THREAD)) {
1579     // propagate failure back to caller
1580     return false;
1581   }
1582 
1583   // rewrite constant pool references in the class_type_annotations:
1584   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1585     // propagate failure back to caller
1586     return false;
1587   }
1588 
1589   // rewrite constant pool references in the fields_type_annotations:
1590   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1591     // propagate failure back to caller
1592     return false;
1593   }
1594 
1595   // rewrite constant pool references in the methods_type_annotations:
1596   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1597     // propagate failure back to caller
1598     return false;
1599   }
1600 
1601   // There can be type annotations in the Code part of a method_info attribute.
1602   // These annotations are not accessible, even by reflection.
1603   // Currently they are not even parsed by the ClassFileParser.
1604   // If runtime access is added they will also need to be rewritten.
1605 
1606   // rewrite source file name index:
1607   u2 source_file_name_idx = scratch_class->source_file_name_index();
1608   if (source_file_name_idx != 0) {
1609     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1610     if (new_source_file_name_idx != 0) {
1611       scratch_class->set_source_file_name_index(new_source_file_name_idx);
1612     }
1613   }
1614 
1615   // rewrite class generic signature index:
1616   u2 generic_signature_index = scratch_class->generic_signature_index();
1617   if (generic_signature_index != 0) {
1618     u2 new_generic_signature_index = find_new_index(generic_signature_index);
1619     if (new_generic_signature_index != 0) {
1620       scratch_class->set_generic_signature_index(new_generic_signature_index);
1621     }
1622   }
1623 
1624   return true;
1625 } // end rewrite_cp_refs()
1626 
1627 // Rewrite constant pool references in the methods.
1628 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1629        instanceKlassHandle scratch_class, TRAPS) {
1630 
1631   Array<Method*>* methods = scratch_class->methods();
1632 
1633   if (methods == NULL || methods->length() == 0) {
1634     // no methods so nothing to do
1635     return true;
1636   }
1637 
1638   // rewrite constant pool references in the methods:
1639   for (int i = methods->length() - 1; i >= 0; i--) {
1640     methodHandle method(THREAD, methods->at(i));
1641     methodHandle new_method;
1642     rewrite_cp_refs_in_method(method, &new_method, THREAD);
1643     if (!new_method.is_null()) {
1644       // the method has been replaced so save the new method version
1645       // even in the case of an exception.  original method is on the
1646       // deallocation list.
1647       methods->at_put(i, new_method());
1648     }
1649     if (HAS_PENDING_EXCEPTION) {
1650       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1651       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1652       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1653         ("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()));
1654       // Need to clear pending exception here as the super caller sets
1655       // the JVMTI_ERROR_INTERNAL if the returned value is false.
1656       CLEAR_PENDING_EXCEPTION;
1657       return false;
1658     }
1659   }
1660 
1661   return true;
1662 }
1663 
1664 
1665 // Rewrite constant pool references in the specific method. This code
1666 // was adapted from Rewriter::rewrite_method().
1667 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1668        methodHandle *new_method_p, TRAPS) {
1669 
1670   *new_method_p = methodHandle();  // default is no new method
1671 
1672   // We cache a pointer to the bytecodes here in code_base. If GC
1673   // moves the Method*, then the bytecodes will also move which
1674   // will likely cause a crash. We create a No_Safepoint_Verifier
1675   // object to detect whether we pass a possible safepoint in this
1676   // code block.
1677   No_Safepoint_Verifier nsv;
1678 
1679   // Bytecodes and their length
1680   address code_base = method->code_base();
1681   int code_length = method->code_size();
1682 
1683   int bc_length;
1684   for (int bci = 0; bci < code_length; bci += bc_length) {
1685     address bcp = code_base + bci;
1686     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1687 
1688     bc_length = Bytecodes::length_for(c);
1689     if (bc_length == 0) {
1690       // More complicated bytecodes report a length of zero so
1691       // we have to try again a slightly different way.
1692       bc_length = Bytecodes::length_at(method(), bcp);
1693     }
1694 
1695     assert(bc_length != 0, "impossible bytecode length");
1696 
1697     switch (c) {
1698       case Bytecodes::_ldc:
1699       {
1700         int cp_index = *(bcp + 1);
1701         int new_index = find_new_index(cp_index);
1702 
1703         if (StressLdcRewrite && new_index == 0) {
1704           // If we are stressing ldc -> ldc_w rewriting, then we
1705           // always need a new_index value.
1706           new_index = cp_index;
1707         }
1708         if (new_index != 0) {
1709           // the original index is mapped so we have more work to do
1710           if (!StressLdcRewrite && new_index <= max_jubyte) {
1711             // The new value can still use ldc instead of ldc_w
1712             // unless we are trying to stress ldc -> ldc_w rewriting
1713             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1714               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1715               bcp, cp_index, new_index));
1716             *(bcp + 1) = new_index;
1717           } else {
1718             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1719               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1720               Bytecodes::name(c), bcp, cp_index, new_index));
1721             // the new value needs ldc_w instead of ldc
1722             u_char inst_buffer[4]; // max instruction size is 4 bytes
1723             bcp = (address)inst_buffer;
1724             // construct new instruction sequence
1725             *bcp = Bytecodes::_ldc_w;
1726             bcp++;
1727             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1728             // See comment below for difference between put_Java_u2()
1729             // and put_native_u2().
1730             Bytes::put_Java_u2(bcp, new_index);
1731 
1732             Relocator rc(method, NULL /* no RelocatorListener needed */);
1733             methodHandle m;
1734             {
1735               Pause_No_Safepoint_Verifier pnsv(&nsv);
1736 
1737               // ldc is 2 bytes and ldc_w is 3 bytes
1738               m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1739             }
1740 
1741             // return the new method so that the caller can update
1742             // the containing class
1743             *new_method_p = method = m;
1744             // switch our bytecode processing loop from the old method
1745             // to the new method
1746             code_base = method->code_base();
1747             code_length = method->code_size();
1748             bcp = code_base + bci;
1749             c = (Bytecodes::Code)(*bcp);
1750             bc_length = Bytecodes::length_for(c);
1751             assert(bc_length != 0, "sanity check");
1752           } // end we need ldc_w instead of ldc
1753         } // end if there is a mapped index
1754       } break;
1755 
1756       // these bytecodes have a two-byte constant pool index
1757       case Bytecodes::_anewarray      : // fall through
1758       case Bytecodes::_checkcast      : // fall through
1759       case Bytecodes::_getfield       : // fall through
1760       case Bytecodes::_getstatic      : // fall through
1761       case Bytecodes::_instanceof     : // fall through
1762       case Bytecodes::_invokedynamic  : // fall through
1763       case Bytecodes::_invokeinterface: // fall through
1764       case Bytecodes::_invokespecial  : // fall through
1765       case Bytecodes::_invokestatic   : // fall through
1766       case Bytecodes::_invokevirtual  : // fall through
1767       case Bytecodes::_ldc_w          : // fall through
1768       case Bytecodes::_ldc2_w         : // fall through
1769       case Bytecodes::_multianewarray : // fall through
1770       case Bytecodes::_new            : // fall through
1771       case Bytecodes::_putfield       : // fall through
1772       case Bytecodes::_putstatic      :
1773       {
1774         address p = bcp + 1;
1775         int cp_index = Bytes::get_Java_u2(p);
1776         int new_index = find_new_index(cp_index);
1777         if (new_index != 0) {
1778           // the original index is mapped so update w/ new value
1779           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1780             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1781             bcp, cp_index, new_index));
1782           // Rewriter::rewrite_method() uses put_native_u2() in this
1783           // situation because it is reusing the constant pool index
1784           // location for a native index into the ConstantPoolCache.
1785           // Since we are updating the constant pool index prior to
1786           // verification and ConstantPoolCache initialization, we
1787           // need to keep the new index in Java byte order.
1788           Bytes::put_Java_u2(p, new_index);
1789         }
1790       } break;
1791     }
1792   } // end for each bytecode
1793 
1794   // We also need to rewrite the parameter name indexes, if there is
1795   // method parameter data present
1796   if(method->has_method_parameters()) {
1797     const int len = method->method_parameters_length();
1798     MethodParametersElement* elem = method->method_parameters_start();
1799 
1800     for (int i = 0; i < len; i++) {
1801       const u2 cp_index = elem[i].name_cp_index;
1802       const u2 new_cp_index = find_new_index(cp_index);
1803       if (new_cp_index != 0) {
1804         elem[i].name_cp_index = new_cp_index;
1805       }
1806     }
1807   }
1808 } // end rewrite_cp_refs_in_method()
1809 
1810 
1811 // Rewrite constant pool references in the class_annotations field.
1812 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1813        instanceKlassHandle scratch_class, TRAPS) {
1814 
1815   AnnotationArray* class_annotations = scratch_class->class_annotations();
1816   if (class_annotations == NULL || class_annotations->length() == 0) {
1817     // no class_annotations so nothing to do
1818     return true;
1819   }
1820 
1821   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1822     ("class_annotations length=%d", class_annotations->length()));
1823 
1824   int byte_i = 0;  // byte index into class_annotations
1825   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1826            THREAD);
1827 }
1828 
1829 
1830 // Rewrite constant pool references in an annotations typeArray. This
1831 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1832 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1833 //
1834 // annotations_typeArray {
1835 //   u2 num_annotations;
1836 //   annotation annotations[num_annotations];
1837 // }
1838 //
1839 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1840        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1841 
1842   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1843     // not enough room for num_annotations field
1844     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1845       ("length() is too small for num_annotations field"));
1846     return false;
1847   }
1848 
1849   u2 num_annotations = Bytes::get_Java_u2((address)
1850                          annotations_typeArray->adr_at(byte_i_ref));
1851   byte_i_ref += 2;
1852 
1853   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1854     ("num_annotations=%d", num_annotations));
1855 
1856   int calc_num_annotations = 0;
1857   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1858     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1859            byte_i_ref, THREAD)) {
1860       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1861         ("bad annotation_struct at %d", calc_num_annotations));
1862       // propagate failure back to caller
1863       return false;
1864     }
1865   }
1866   assert(num_annotations == calc_num_annotations, "sanity check");
1867 
1868   return true;
1869 } // end rewrite_cp_refs_in_annotations_typeArray()
1870 
1871 
1872 // Rewrite constant pool references in the annotation struct portion of
1873 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1874 // the 2nd-edition of the VM spec:
1875 //
1876 // struct annotation {
1877 //   u2 type_index;
1878 //   u2 num_element_value_pairs;
1879 //   {
1880 //     u2 element_name_index;
1881 //     element_value value;
1882 //   } element_value_pairs[num_element_value_pairs];
1883 // }
1884 //
1885 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1886        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1887   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1888     // not enough room for smallest annotation_struct
1889     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1890       ("length() is too small for annotation_struct"));
1891     return false;
1892   }
1893 
1894   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1895                     byte_i_ref, "mapped old type_index=%d", THREAD);
1896 
1897   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1898                                  annotations_typeArray->adr_at(byte_i_ref));
1899   byte_i_ref += 2;
1900 
1901   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1902     ("type_index=%d  num_element_value_pairs=%d", type_index,
1903     num_element_value_pairs));
1904 
1905   int calc_num_element_value_pairs = 0;
1906   for (; calc_num_element_value_pairs < num_element_value_pairs;
1907        calc_num_element_value_pairs++) {
1908     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1909       // not enough room for another element_name_index, let alone
1910       // the rest of another component
1911       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1912         ("length() is too small for element_name_index"));
1913       return false;
1914     }
1915 
1916     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1917                               annotations_typeArray, byte_i_ref,
1918                               "mapped old element_name_index=%d", THREAD);
1919 
1920     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1921       ("element_name_index=%d", element_name_index));
1922 
1923     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1924            byte_i_ref, THREAD)) {
1925       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1926         ("bad element_value at %d", calc_num_element_value_pairs));
1927       // propagate failure back to caller
1928       return false;
1929     }
1930   } // end for each component
1931   assert(num_element_value_pairs == calc_num_element_value_pairs,
1932     "sanity check");
1933 
1934   return true;
1935 } // end rewrite_cp_refs_in_annotation_struct()
1936 
1937 
1938 // Rewrite a constant pool reference at the current position in
1939 // annotations_typeArray if needed. Returns the original constant
1940 // pool reference if a rewrite was not needed or the new constant
1941 // pool reference if a rewrite was needed.
1942 PRAGMA_DIAG_PUSH
1943 PRAGMA_FORMAT_NONLITERAL_IGNORED
1944 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1945      AnnotationArray* annotations_typeArray, int &byte_i_ref,
1946      const char * trace_mesg, TRAPS) {
1947 
1948   address cp_index_addr = (address)
1949     annotations_typeArray->adr_at(byte_i_ref);
1950   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1951   u2 new_cp_index = find_new_index(old_cp_index);
1952   if (new_cp_index != 0) {
1953     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1954     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1955     old_cp_index = new_cp_index;
1956   }
1957   byte_i_ref += 2;
1958   return old_cp_index;
1959 }
1960 PRAGMA_DIAG_POP
1961 
1962 
1963 // Rewrite constant pool references in the element_value portion of an
1964 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1965 // the 2nd-edition of the VM spec:
1966 //
1967 // struct element_value {
1968 //   u1 tag;
1969 //   union {
1970 //     u2 const_value_index;
1971 //     {
1972 //       u2 type_name_index;
1973 //       u2 const_name_index;
1974 //     } enum_const_value;
1975 //     u2 class_info_index;
1976 //     annotation annotation_value;
1977 //     struct {
1978 //       u2 num_values;
1979 //       element_value values[num_values];
1980 //     } array_value;
1981 //   } value;
1982 // }
1983 //
1984 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1985        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1986 
1987   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1988     // not enough room for a tag let alone the rest of an element_value
1989     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1990       ("length() is too small for a tag"));
1991     return false;
1992   }
1993 
1994   u1 tag = annotations_typeArray->at(byte_i_ref);
1995   byte_i_ref++;
1996   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1997 
1998   switch (tag) {
1999     // These BaseType tag values are from Table 4.2 in VM spec:
2000     case 'B':  // byte
2001     case 'C':  // char
2002     case 'D':  // double
2003     case 'F':  // float
2004     case 'I':  // int
2005     case 'J':  // long
2006     case 'S':  // short
2007     case 'Z':  // boolean
2008 
2009     // The remaining tag values are from Table 4.8 in the 2nd-edition of
2010     // the VM spec:
2011     case 's':
2012     {
2013       // For the above tag values (including the BaseType values),
2014       // value.const_value_index is right union field.
2015 
2016       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2017         // not enough room for a const_value_index
2018         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2019           ("length() is too small for a const_value_index"));
2020         return false;
2021       }
2022 
2023       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2024                                annotations_typeArray, byte_i_ref,
2025                                "mapped old const_value_index=%d", THREAD);
2026 
2027       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2028         ("const_value_index=%d", const_value_index));
2029     } break;
2030 
2031     case 'e':
2032     {
2033       // for the above tag value, value.enum_const_value is right union field
2034 
2035       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2036         // not enough room for a enum_const_value
2037         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2038           ("length() is too small for a enum_const_value"));
2039         return false;
2040       }
2041 
2042       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2043                              annotations_typeArray, byte_i_ref,
2044                              "mapped old type_name_index=%d", THREAD);
2045 
2046       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2047                               annotations_typeArray, byte_i_ref,
2048                               "mapped old const_name_index=%d", THREAD);
2049 
2050       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2051         ("type_name_index=%d  const_name_index=%d", type_name_index,
2052         const_name_index));
2053     } break;
2054 
2055     case 'c':
2056     {
2057       // for the above tag value, value.class_info_index is right union field
2058 
2059       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2060         // not enough room for a class_info_index
2061         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2062           ("length() is too small for a class_info_index"));
2063         return false;
2064       }
2065 
2066       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2067                               annotations_typeArray, byte_i_ref,
2068                               "mapped old class_info_index=%d", THREAD);
2069 
2070       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2071         ("class_info_index=%d", class_info_index));
2072     } break;
2073 
2074     case '@':
2075       // For the above tag value, value.attr_value is the right union
2076       // field. This is a nested annotation.
2077       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2078              byte_i_ref, THREAD)) {
2079         // propagate failure back to caller
2080         return false;
2081       }
2082       break;
2083 
2084     case '[':
2085     {
2086       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2087         // not enough room for a num_values field
2088         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2089           ("length() is too small for a num_values field"));
2090         return false;
2091       }
2092 
2093       // For the above tag value, value.array_value is the right union
2094       // field. This is an array of nested element_value.
2095       u2 num_values = Bytes::get_Java_u2((address)
2096                         annotations_typeArray->adr_at(byte_i_ref));
2097       byte_i_ref += 2;
2098       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
2099 
2100       int calc_num_values = 0;
2101       for (; calc_num_values < num_values; calc_num_values++) {
2102         if (!rewrite_cp_refs_in_element_value(
2103                annotations_typeArray, byte_i_ref, THREAD)) {
2104           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2105             ("bad nested element_value at %d", calc_num_values));
2106           // propagate failure back to caller
2107           return false;
2108         }
2109       }
2110       assert(num_values == calc_num_values, "sanity check");
2111     } break;
2112 
2113     default:
2114       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
2115       return false;
2116   } // end decode tag field
2117 
2118   return true;
2119 } // end rewrite_cp_refs_in_element_value()
2120 
2121 
2122 // Rewrite constant pool references in a fields_annotations field.
2123 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2124        instanceKlassHandle scratch_class, TRAPS) {
2125 
2126   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2127 
2128   if (fields_annotations == NULL || fields_annotations->length() == 0) {
2129     // no fields_annotations so nothing to do
2130     return true;
2131   }
2132 
2133   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2134     ("fields_annotations length=%d", fields_annotations->length()));
2135 
2136   for (int i = 0; i < fields_annotations->length(); i++) {
2137     AnnotationArray* field_annotations = fields_annotations->at(i);
2138     if (field_annotations == NULL || field_annotations->length() == 0) {
2139       // this field does not have any annotations so skip it
2140       continue;
2141     }
2142 
2143     int byte_i = 0;  // byte index into field_annotations
2144     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2145            THREAD)) {
2146       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2147         ("bad field_annotations at %d", i));
2148       // propagate failure back to caller
2149       return false;
2150     }
2151   }
2152 
2153   return true;
2154 } // end rewrite_cp_refs_in_fields_annotations()
2155 
2156 
2157 // Rewrite constant pool references in a methods_annotations field.
2158 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2159        instanceKlassHandle scratch_class, TRAPS) {
2160 
2161   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2162     Method* m = scratch_class->methods()->at(i);
2163     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2164 
2165     if (method_annotations == NULL || method_annotations->length() == 0) {
2166       // this method does not have any annotations so skip it
2167       continue;
2168     }
2169 
2170     int byte_i = 0;  // byte index into method_annotations
2171     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2172            THREAD)) {
2173       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2174         ("bad method_annotations at %d", i));
2175       // propagate failure back to caller
2176       return false;
2177     }
2178   }
2179 
2180   return true;
2181 } // end rewrite_cp_refs_in_methods_annotations()
2182 
2183 
2184 // Rewrite constant pool references in a methods_parameter_annotations
2185 // field. This "structure" is adapted from the
2186 // RuntimeVisibleParameterAnnotations_attribute described in section
2187 // 4.8.17 of the 2nd-edition of the VM spec:
2188 //
2189 // methods_parameter_annotations_typeArray {
2190 //   u1 num_parameters;
2191 //   {
2192 //     u2 num_annotations;
2193 //     annotation annotations[num_annotations];
2194 //   } parameter_annotations[num_parameters];
2195 // }
2196 //
2197 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2198        instanceKlassHandle scratch_class, TRAPS) {
2199 
2200   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2201     Method* m = scratch_class->methods()->at(i);
2202     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2203     if (method_parameter_annotations == NULL
2204         || method_parameter_annotations->length() == 0) {
2205       // this method does not have any parameter annotations so skip it
2206       continue;
2207     }
2208 
2209     if (method_parameter_annotations->length() < 1) {
2210       // not enough room for a num_parameters field
2211       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2212         ("length() is too small for a num_parameters field at %d", i));
2213       return false;
2214     }
2215 
2216     int byte_i = 0;  // byte index into method_parameter_annotations
2217 
2218     u1 num_parameters = method_parameter_annotations->at(byte_i);
2219     byte_i++;
2220 
2221     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2222       ("num_parameters=%d", num_parameters));
2223 
2224     int calc_num_parameters = 0;
2225     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2226       if (!rewrite_cp_refs_in_annotations_typeArray(
2227              method_parameter_annotations, byte_i, THREAD)) {
2228         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2229           ("bad method_parameter_annotations at %d", calc_num_parameters));
2230         // propagate failure back to caller
2231         return false;
2232       }
2233     }
2234     assert(num_parameters == calc_num_parameters, "sanity check");
2235   }
2236 
2237   return true;
2238 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2239 
2240 
2241 // Rewrite constant pool references in a methods_default_annotations
2242 // field. This "structure" is adapted from the AnnotationDefault_attribute
2243 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2244 //
2245 // methods_default_annotations_typeArray {
2246 //   element_value default_value;
2247 // }
2248 //
2249 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2250        instanceKlassHandle scratch_class, TRAPS) {
2251 
2252   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2253     Method* m = scratch_class->methods()->at(i);
2254     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2255     if (method_default_annotations == NULL
2256         || method_default_annotations->length() == 0) {
2257       // this method does not have any default annotations so skip it
2258       continue;
2259     }
2260 
2261     int byte_i = 0;  // byte index into method_default_annotations
2262 
2263     if (!rewrite_cp_refs_in_element_value(
2264            method_default_annotations, byte_i, THREAD)) {
2265       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2266         ("bad default element_value at %d", i));
2267       // propagate failure back to caller
2268       return false;
2269     }
2270   }
2271 
2272   return true;
2273 } // end rewrite_cp_refs_in_methods_default_annotations()
2274 
2275 
2276 // Rewrite constant pool references in a class_type_annotations field.
2277 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2278        instanceKlassHandle scratch_class, TRAPS) {
2279 
2280   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2281   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2282     // no class_type_annotations so nothing to do
2283     return true;
2284   }
2285 
2286   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2287     ("class_type_annotations length=%d", class_type_annotations->length()));
2288 
2289   int byte_i = 0;  // byte index into class_type_annotations
2290   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2291       byte_i, "ClassFile", THREAD);
2292 } // end rewrite_cp_refs_in_class_type_annotations()
2293 
2294 
2295 // Rewrite constant pool references in a fields_type_annotations field.
2296 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2297        instanceKlassHandle scratch_class, TRAPS) {
2298 
2299   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2300   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2301     // no fields_type_annotations so nothing to do
2302     return true;
2303   }
2304 
2305   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2306     ("fields_type_annotations length=%d", fields_type_annotations->length()));
2307 
2308   for (int i = 0; i < fields_type_annotations->length(); i++) {
2309     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2310     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2311       // this field does not have any annotations so skip it
2312       continue;
2313     }
2314 
2315     int byte_i = 0;  // byte index into field_type_annotations
2316     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2317            byte_i, "field_info", THREAD)) {
2318       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2319         ("bad field_type_annotations at %d", i));
2320       // propagate failure back to caller
2321       return false;
2322     }
2323   }
2324 
2325   return true;
2326 } // end rewrite_cp_refs_in_fields_type_annotations()
2327 
2328 
2329 // Rewrite constant pool references in a methods_type_annotations field.
2330 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2331        instanceKlassHandle scratch_class, TRAPS) {
2332 
2333   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2334     Method* m = scratch_class->methods()->at(i);
2335     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2336 
2337     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2338       // this method does not have any annotations so skip it
2339       continue;
2340     }
2341 
2342     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2343         ("methods type_annotations length=%d", method_type_annotations->length()));
2344 
2345     int byte_i = 0;  // byte index into method_type_annotations
2346     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2347            byte_i, "method_info", THREAD)) {
2348       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2349         ("bad method_type_annotations at %d", i));
2350       // propagate failure back to caller
2351       return false;
2352     }
2353   }
2354 
2355   return true;
2356 } // end rewrite_cp_refs_in_methods_type_annotations()
2357 
2358 
2359 // Rewrite constant pool references in a type_annotations
2360 // field. This "structure" is adapted from the
2361 // RuntimeVisibleTypeAnnotations_attribute described in
2362 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2363 //
2364 // type_annotations_typeArray {
2365 //   u2              num_annotations;
2366 //   type_annotation annotations[num_annotations];
2367 // }
2368 //
2369 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2370        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2371        const char * location_mesg, TRAPS) {
2372 
2373   if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2374     // not enough room for num_annotations field
2375     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2376       ("length() is too small for num_annotations field"));
2377     return false;
2378   }
2379 
2380   u2 num_annotations = Bytes::get_Java_u2((address)
2381                          type_annotations_typeArray->adr_at(byte_i_ref));
2382   byte_i_ref += 2;
2383 
2384   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2385     ("num_type_annotations=%d", num_annotations));
2386 
2387   int calc_num_annotations = 0;
2388   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2389     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2390            byte_i_ref, location_mesg, THREAD)) {
2391       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2392         ("bad type_annotation_struct at %d", calc_num_annotations));
2393       // propagate failure back to caller
2394       return false;
2395     }
2396   }
2397   assert(num_annotations == calc_num_annotations, "sanity check");
2398 
2399   if (byte_i_ref != type_annotations_typeArray->length()) {
2400     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2401       ("read wrong amount of bytes at end of processing "
2402        "type_annotations_typeArray (%d of %d bytes were read)",
2403        byte_i_ref, type_annotations_typeArray->length()));
2404     return false;
2405   }
2406 
2407   return true;
2408 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2409 
2410 
2411 // Rewrite constant pool references in a type_annotation
2412 // field. This "structure" is adapted from the
2413 // RuntimeVisibleTypeAnnotations_attribute described in
2414 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2415 //
2416 // type_annotation {
2417 //   u1 target_type;
2418 //   union {
2419 //     type_parameter_target;
2420 //     supertype_target;
2421 //     type_parameter_bound_target;
2422 //     empty_target;
2423 //     method_formal_parameter_target;
2424 //     throws_target;
2425 //     localvar_target;
2426 //     catch_target;
2427 //     offset_target;
2428 //     type_argument_target;
2429 //   } target_info;
2430 //   type_path target_path;
2431 //   annotation anno;
2432 // }
2433 //
2434 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2435        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2436        const char * location_mesg, TRAPS) {
2437 
2438   if (!skip_type_annotation_target(type_annotations_typeArray,
2439          byte_i_ref, location_mesg, THREAD)) {
2440     return false;
2441   }
2442 
2443   if (!skip_type_annotation_type_path(type_annotations_typeArray,
2444          byte_i_ref, THREAD)) {
2445     return false;
2446   }
2447 
2448   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2449          byte_i_ref, THREAD)) {
2450     return false;
2451   }
2452 
2453   return true;
2454 } // end rewrite_cp_refs_in_type_annotation_struct()
2455 
2456 
2457 // Read, verify and skip over the target_type and target_info part
2458 // so that rewriting can continue in the later parts of the struct.
2459 //
2460 // u1 target_type;
2461 // union {
2462 //   type_parameter_target;
2463 //   supertype_target;
2464 //   type_parameter_bound_target;
2465 //   empty_target;
2466 //   method_formal_parameter_target;
2467 //   throws_target;
2468 //   localvar_target;
2469 //   catch_target;
2470 //   offset_target;
2471 //   type_argument_target;
2472 // } target_info;
2473 //
2474 bool VM_RedefineClasses::skip_type_annotation_target(
2475        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2476        const char * location_mesg, TRAPS) {
2477 
2478   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2479     // not enough room for a target_type let alone the rest of a type_annotation
2480     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2481       ("length() is too small for a target_type"));
2482     return false;
2483   }
2484 
2485   u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2486   byte_i_ref += 1;
2487   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("target_type=0x%.2x", target_type));
2488   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("location=%s", location_mesg));
2489 
2490   // Skip over target_info
2491   switch (target_type) {
2492     case 0x00:
2493     // kind: type parameter declaration of generic class or interface
2494     // location: ClassFile
2495     case 0x01:
2496     // kind: type parameter declaration of generic method or constructor
2497     // location: method_info
2498 
2499     {
2500       // struct:
2501       // type_parameter_target {
2502       //   u1 type_parameter_index;
2503       // }
2504       //
2505       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2506         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2507           ("length() is too small for a type_parameter_target"));
2508         return false;
2509       }
2510 
2511       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2512       byte_i_ref += 1;
2513 
2514       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2515         ("type_parameter_target: type_parameter_index=%d",
2516          type_parameter_index));
2517     } break;
2518 
2519     case 0x10:
2520     // kind: type in extends clause of class or interface declaration
2521     //       (including the direct superclass of an anonymous class declaration),
2522     //       or in implements clause of interface declaration
2523     // location: ClassFile
2524 
2525     {
2526       // struct:
2527       // supertype_target {
2528       //   u2 supertype_index;
2529       // }
2530       //
2531       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2532         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2533           ("length() is too small for a supertype_target"));
2534         return false;
2535       }
2536 
2537       u2 supertype_index = Bytes::get_Java_u2((address)
2538                              type_annotations_typeArray->adr_at(byte_i_ref));
2539       byte_i_ref += 2;
2540 
2541       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2542         ("supertype_target: supertype_index=%d", supertype_index));
2543     } break;
2544 
2545     case 0x11:
2546     // kind: type in bound of type parameter declaration of generic class or interface
2547     // location: ClassFile
2548     case 0x12:
2549     // kind: type in bound of type parameter declaration of generic method or constructor
2550     // location: method_info
2551 
2552     {
2553       // struct:
2554       // type_parameter_bound_target {
2555       //   u1 type_parameter_index;
2556       //   u1 bound_index;
2557       // }
2558       //
2559       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2560         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2561           ("length() is too small for a type_parameter_bound_target"));
2562         return false;
2563       }
2564 
2565       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2566       byte_i_ref += 1;
2567       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2568       byte_i_ref += 1;
2569 
2570       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2571         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d",
2572          type_parameter_index, bound_index));
2573     } break;
2574 
2575     case 0x13:
2576     // kind: type in field declaration
2577     // location: field_info
2578     case 0x14:
2579     // kind: return type of method, or type of newly constructed object
2580     // location: method_info
2581     case 0x15:
2582     // kind: receiver type of method or constructor
2583     // location: method_info
2584 
2585     {
2586       // struct:
2587       // empty_target {
2588       // }
2589       //
2590       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2591         ("empty_target"));
2592     } break;
2593 
2594     case 0x16:
2595     // kind: type in formal parameter declaration of method, constructor, or lambda expression
2596     // location: method_info
2597 
2598     {
2599       // struct:
2600       // formal_parameter_target {
2601       //   u1 formal_parameter_index;
2602       // }
2603       //
2604       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2605         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2606           ("length() is too small for a formal_parameter_target"));
2607         return false;
2608       }
2609 
2610       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2611       byte_i_ref += 1;
2612 
2613       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2614         ("formal_parameter_target: formal_parameter_index=%d",
2615          formal_parameter_index));
2616     } break;
2617 
2618     case 0x17:
2619     // kind: type in throws clause of method or constructor
2620     // location: method_info
2621 
2622     {
2623       // struct:
2624       // throws_target {
2625       //   u2 throws_type_index
2626       // }
2627       //
2628       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2629         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2630           ("length() is too small for a throws_target"));
2631         return false;
2632       }
2633 
2634       u2 throws_type_index = Bytes::get_Java_u2((address)
2635                                type_annotations_typeArray->adr_at(byte_i_ref));
2636       byte_i_ref += 2;
2637 
2638       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2639         ("throws_target: throws_type_index=%d", throws_type_index));
2640     } break;
2641 
2642     case 0x40:
2643     // kind: type in local variable declaration
2644     // location: Code
2645     case 0x41:
2646     // kind: type in resource variable declaration
2647     // location: Code
2648 
2649     {
2650       // struct:
2651       // localvar_target {
2652       //   u2 table_length;
2653       //   struct {
2654       //     u2 start_pc;
2655       //     u2 length;
2656       //     u2 index;
2657       //   } table[table_length];
2658       // }
2659       //
2660       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2661         // not enough room for a table_length let alone the rest of a localvar_target
2662         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2663           ("length() is too small for a localvar_target table_length"));
2664         return false;
2665       }
2666 
2667       u2 table_length = Bytes::get_Java_u2((address)
2668                           type_annotations_typeArray->adr_at(byte_i_ref));
2669       byte_i_ref += 2;
2670 
2671       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2672         ("localvar_target: table_length=%d", table_length));
2673 
2674       int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2675       int table_size = table_length * table_struct_size;
2676 
2677       if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2678         // not enough room for a table
2679         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2680           ("length() is too small for a table array of length %d", table_length));
2681         return false;
2682       }
2683 
2684       // Skip over table
2685       byte_i_ref += table_size;
2686     } break;
2687 
2688     case 0x42:
2689     // kind: type in exception parameter declaration
2690     // location: Code
2691 
2692     {
2693       // struct:
2694       // catch_target {
2695       //   u2 exception_table_index;
2696       // }
2697       //
2698       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2699         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2700           ("length() is too small for a catch_target"));
2701         return false;
2702       }
2703 
2704       u2 exception_table_index = Bytes::get_Java_u2((address)
2705                                    type_annotations_typeArray->adr_at(byte_i_ref));
2706       byte_i_ref += 2;
2707 
2708       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2709         ("catch_target: exception_table_index=%d", exception_table_index));
2710     } break;
2711 
2712     case 0x43:
2713     // kind: type in instanceof expression
2714     // location: Code
2715     case 0x44:
2716     // kind: type in new expression
2717     // location: Code
2718     case 0x45:
2719     // kind: type in method reference expression using ::new
2720     // location: Code
2721     case 0x46:
2722     // kind: type in method reference expression using ::Identifier
2723     // location: Code
2724 
2725     {
2726       // struct:
2727       // offset_target {
2728       //   u2 offset;
2729       // }
2730       //
2731       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2732         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2733           ("length() is too small for a offset_target"));
2734         return false;
2735       }
2736 
2737       u2 offset = Bytes::get_Java_u2((address)
2738                     type_annotations_typeArray->adr_at(byte_i_ref));
2739       byte_i_ref += 2;
2740 
2741       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2742         ("offset_target: offset=%d", offset));
2743     } break;
2744 
2745     case 0x47:
2746     // kind: type in cast expression
2747     // location: Code
2748     case 0x48:
2749     // kind: type argument for generic constructor in new expression or
2750     //       explicit constructor invocation statement
2751     // location: Code
2752     case 0x49:
2753     // kind: type argument for generic method in method invocation expression
2754     // location: Code
2755     case 0x4A:
2756     // kind: type argument for generic constructor in method reference expression using ::new
2757     // location: Code
2758     case 0x4B:
2759     // kind: type argument for generic method in method reference expression using ::Identifier
2760     // location: Code
2761 
2762     {
2763       // struct:
2764       // type_argument_target {
2765       //   u2 offset;
2766       //   u1 type_argument_index;
2767       // }
2768       //
2769       if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2770         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2771           ("length() is too small for a type_argument_target"));
2772         return false;
2773       }
2774 
2775       u2 offset = Bytes::get_Java_u2((address)
2776                     type_annotations_typeArray->adr_at(byte_i_ref));
2777       byte_i_ref += 2;
2778       u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2779       byte_i_ref += 1;
2780 
2781       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2782         ("type_argument_target: offset=%d, type_argument_index=%d",
2783          offset, type_argument_index));
2784     } break;
2785 
2786     default:
2787       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2788         ("unknown target_type"));
2789 #ifdef ASSERT
2790       ShouldNotReachHere();
2791 #endif
2792       return false;
2793   }
2794 
2795   return true;
2796 } // end skip_type_annotation_target()
2797 
2798 
2799 // Read, verify and skip over the type_path part so that rewriting
2800 // can continue in the later parts of the struct.
2801 //
2802 // type_path {
2803 //   u1 path_length;
2804 //   {
2805 //     u1 type_path_kind;
2806 //     u1 type_argument_index;
2807 //   } path[path_length];
2808 // }
2809 //
2810 bool VM_RedefineClasses::skip_type_annotation_type_path(
2811        AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2812 
2813   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2814     // not enough room for a path_length let alone the rest of the type_path
2815     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2816       ("length() is too small for a type_path"));
2817     return false;
2818   }
2819 
2820   u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2821   byte_i_ref += 1;
2822 
2823   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2824     ("type_path: path_length=%d", path_length));
2825 
2826   int calc_path_length = 0;
2827   for (; calc_path_length < path_length; calc_path_length++) {
2828     if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2829       // not enough room for a path
2830       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2831         ("length() is too small for path entry %d of %d",
2832          calc_path_length, path_length));
2833       return false;
2834     }
2835 
2836     u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2837     byte_i_ref += 1;
2838     u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2839     byte_i_ref += 1;
2840 
2841     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2842       ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2843        calc_path_length, type_path_kind, type_argument_index));
2844 
2845     if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2846       // not enough room for a path
2847       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2848         ("inconsistent type_path values"));
2849       return false;
2850     }
2851   }
2852   assert(path_length == calc_path_length, "sanity check");
2853 
2854   return true;
2855 } // end skip_type_annotation_type_path()
2856 
2857 
2858 // Rewrite constant pool references in the method's stackmap table.
2859 // These "structures" are adapted from the StackMapTable_attribute that
2860 // is described in section 4.8.4 of the 6.0 version of the VM spec
2861 // (dated 2005.10.26):
2862 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2863 //
2864 // stack_map {
2865 //   u2 number_of_entries;
2866 //   stack_map_frame entries[number_of_entries];
2867 // }
2868 //
2869 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2870        methodHandle method, TRAPS) {
2871 
2872   if (!method->has_stackmap_table()) {
2873     return;
2874   }
2875 
2876   AnnotationArray* stackmap_data = method->stackmap_data();
2877   address stackmap_p = (address)stackmap_data->adr_at(0);
2878   address stackmap_end = stackmap_p + stackmap_data->length();
2879 
2880   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2881   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2882   stackmap_p += 2;
2883 
2884   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2885     ("number_of_entries=%u", number_of_entries));
2886 
2887   // walk through each stack_map_frame
2888   u2 calc_number_of_entries = 0;
2889   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2890     // The stack_map_frame structure is a u1 frame_type followed by
2891     // 0 or more bytes of data:
2892     //
2893     // union stack_map_frame {
2894     //   same_frame;
2895     //   same_locals_1_stack_item_frame;
2896     //   same_locals_1_stack_item_frame_extended;
2897     //   chop_frame;
2898     //   same_frame_extended;
2899     //   append_frame;
2900     //   full_frame;
2901     // }
2902 
2903     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2904     // The Linux compiler does not like frame_type to be u1 or u2. It
2905     // issues the following warning for the first if-statement below:
2906     //
2907     // "warning: comparison is always true due to limited range of data type"
2908     //
2909     u4 frame_type = *stackmap_p;
2910     stackmap_p++;
2911 
2912     // same_frame {
2913     //   u1 frame_type = SAME; /* 0-63 */
2914     // }
2915     if (frame_type >= 0 && frame_type <= 63) {
2916       // nothing more to do for same_frame
2917     }
2918 
2919     // same_locals_1_stack_item_frame {
2920     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2921     //   verification_type_info stack[1];
2922     // }
2923     else if (frame_type >= 64 && frame_type <= 127) {
2924       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2925         calc_number_of_entries, frame_type, THREAD);
2926     }
2927 
2928     // reserved for future use
2929     else if (frame_type >= 128 && frame_type <= 246) {
2930       // nothing more to do for reserved frame_types
2931     }
2932 
2933     // same_locals_1_stack_item_frame_extended {
2934     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2935     //   u2 offset_delta;
2936     //   verification_type_info stack[1];
2937     // }
2938     else if (frame_type == 247) {
2939       stackmap_p += 2;
2940       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2941         calc_number_of_entries, frame_type, THREAD);
2942     }
2943 
2944     // chop_frame {
2945     //   u1 frame_type = CHOP; /* 248-250 */
2946     //   u2 offset_delta;
2947     // }
2948     else if (frame_type >= 248 && frame_type <= 250) {
2949       stackmap_p += 2;
2950     }
2951 
2952     // same_frame_extended {
2953     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2954     //   u2 offset_delta;
2955     // }
2956     else if (frame_type == 251) {
2957       stackmap_p += 2;
2958     }
2959 
2960     // append_frame {
2961     //   u1 frame_type = APPEND; /* 252-254 */
2962     //   u2 offset_delta;
2963     //   verification_type_info locals[frame_type - 251];
2964     // }
2965     else if (frame_type >= 252 && frame_type <= 254) {
2966       assert(stackmap_p + 2 <= stackmap_end,
2967         "no room for offset_delta");
2968       stackmap_p += 2;
2969       u1 len = frame_type - 251;
2970       for (u1 i = 0; i < len; i++) {
2971         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2972           calc_number_of_entries, frame_type, THREAD);
2973       }
2974     }
2975 
2976     // full_frame {
2977     //   u1 frame_type = FULL_FRAME; /* 255 */
2978     //   u2 offset_delta;
2979     //   u2 number_of_locals;
2980     //   verification_type_info locals[number_of_locals];
2981     //   u2 number_of_stack_items;
2982     //   verification_type_info stack[number_of_stack_items];
2983     // }
2984     else if (frame_type == 255) {
2985       assert(stackmap_p + 2 + 2 <= stackmap_end,
2986         "no room for smallest full_frame");
2987       stackmap_p += 2;
2988 
2989       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2990       stackmap_p += 2;
2991 
2992       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2993         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2994           calc_number_of_entries, frame_type, THREAD);
2995       }
2996 
2997       // Use the largest size for the number_of_stack_items, but only get
2998       // the right number of bytes.
2999       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3000       stackmap_p += 2;
3001 
3002       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3003         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3004           calc_number_of_entries, frame_type, THREAD);
3005       }
3006     }
3007   } // end while there is a stack_map_frame
3008   assert(number_of_entries == calc_number_of_entries, "sanity check");
3009 } // end rewrite_cp_refs_in_stack_map_table()
3010 
3011 
3012 // Rewrite constant pool references in the verification type info
3013 // portion of the method's stackmap table. These "structures" are
3014 // adapted from the StackMapTable_attribute that is described in
3015 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3016 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3017 //
3018 // The verification_type_info structure is a u1 tag followed by 0 or
3019 // more bytes of data:
3020 //
3021 // union verification_type_info {
3022 //   Top_variable_info;
3023 //   Integer_variable_info;
3024 //   Float_variable_info;
3025 //   Long_variable_info;
3026 //   Double_variable_info;
3027 //   Null_variable_info;
3028 //   UninitializedThis_variable_info;
3029 //   Object_variable_info;
3030 //   Uninitialized_variable_info;
3031 // }
3032 //
3033 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3034        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3035        u1 frame_type, TRAPS) {
3036 
3037   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3038   u1 tag = *stackmap_p_ref;
3039   stackmap_p_ref++;
3040 
3041   switch (tag) {
3042   // Top_variable_info {
3043   //   u1 tag = ITEM_Top; /* 0 */
3044   // }
3045   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3046   case 0:  // fall through
3047 
3048   // Integer_variable_info {
3049   //   u1 tag = ITEM_Integer; /* 1 */
3050   // }
3051   case ITEM_Integer:  // fall through
3052 
3053   // Float_variable_info {
3054   //   u1 tag = ITEM_Float; /* 2 */
3055   // }
3056   case ITEM_Float:  // fall through
3057 
3058   // Double_variable_info {
3059   //   u1 tag = ITEM_Double; /* 3 */
3060   // }
3061   case ITEM_Double:  // fall through
3062 
3063   // Long_variable_info {
3064   //   u1 tag = ITEM_Long; /* 4 */
3065   // }
3066   case ITEM_Long:  // fall through
3067 
3068   // Null_variable_info {
3069   //   u1 tag = ITEM_Null; /* 5 */
3070   // }
3071   case ITEM_Null:  // fall through
3072 
3073   // UninitializedThis_variable_info {
3074   //   u1 tag = ITEM_UninitializedThis; /* 6 */
3075   // }
3076   case ITEM_UninitializedThis:
3077     // nothing more to do for the above tag types
3078     break;
3079 
3080   // Object_variable_info {
3081   //   u1 tag = ITEM_Object; /* 7 */
3082   //   u2 cpool_index;
3083   // }
3084   case ITEM_Object:
3085   {
3086     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3087     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3088     u2 new_cp_index = find_new_index(cpool_index);
3089     if (new_cp_index != 0) {
3090       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3091         ("mapped old cpool_index=%d", cpool_index));
3092       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3093       cpool_index = new_cp_index;
3094     }
3095     stackmap_p_ref += 2;
3096 
3097     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3098       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
3099       frame_type, cpool_index));
3100   } break;
3101 
3102   // Uninitialized_variable_info {
3103   //   u1 tag = ITEM_Uninitialized; /* 8 */
3104   //   u2 offset;
3105   // }
3106   case ITEM_Uninitialized:
3107     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3108     stackmap_p_ref += 2;
3109     break;
3110 
3111   default:
3112     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3113       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
3114     ShouldNotReachHere();
3115     break;
3116   } // end switch (tag)
3117 } // end rewrite_cp_refs_in_verification_type_info()
3118 
3119 
3120 // Change the constant pool associated with klass scratch_class to
3121 // scratch_cp. If shrink is true, then scratch_cp_length elements
3122 // are copied from scratch_cp to a smaller constant pool and the
3123 // smaller constant pool is associated with scratch_class.
3124 void VM_RedefineClasses::set_new_constant_pool(
3125        ClassLoaderData* loader_data,
3126        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
3127        int scratch_cp_length, TRAPS) {
3128   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3129 
3130   // scratch_cp is a merged constant pool and has enough space for a
3131   // worst case merge situation. We want to associate the minimum
3132   // sized constant pool with the klass to save space.
3133   ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3134   constantPoolHandle smaller_cp(THREAD, cp);
3135 
3136   // preserve version() value in the smaller copy
3137   int version = scratch_cp->version();
3138   assert(version != 0, "sanity check");
3139   smaller_cp->set_version(version);
3140 
3141   // attach klass to new constant pool
3142   // reference to the cp holder is needed for copy_operands()
3143   smaller_cp->set_pool_holder(scratch_class());
3144 
3145   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3146   if (HAS_PENDING_EXCEPTION) {
3147     // Exception is handled in the caller
3148     loader_data->add_to_deallocate_list(smaller_cp());
3149     return;
3150   }
3151   scratch_cp = smaller_cp;
3152 
3153   // attach new constant pool to klass
3154   scratch_class->set_constants(scratch_cp());
3155 
3156   int i;  // for portability
3157 
3158   // update each field in klass to use new constant pool indices as needed
3159   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3160     jshort cur_index = fs.name_index();
3161     jshort new_index = find_new_index(cur_index);
3162     if (new_index != 0) {
3163       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3164         ("field-name_index change: %d to %d", cur_index, new_index));
3165       fs.set_name_index(new_index);
3166     }
3167     cur_index = fs.signature_index();
3168     new_index = find_new_index(cur_index);
3169     if (new_index != 0) {
3170       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3171         ("field-signature_index change: %d to %d", cur_index, new_index));
3172       fs.set_signature_index(new_index);
3173     }
3174     cur_index = fs.initval_index();
3175     new_index = find_new_index(cur_index);
3176     if (new_index != 0) {
3177       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3178         ("field-initval_index change: %d to %d", cur_index, new_index));
3179       fs.set_initval_index(new_index);
3180     }
3181     cur_index = fs.generic_signature_index();
3182     new_index = find_new_index(cur_index);
3183     if (new_index != 0) {
3184       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3185         ("field-generic_signature change: %d to %d", cur_index, new_index));
3186       fs.set_generic_signature_index(new_index);
3187     }
3188   } // end for each field
3189 
3190   // Update constant pool indices in the inner classes info to use
3191   // new constant indices as needed. The inner classes info is a
3192   // quadruple:
3193   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3194   InnerClassesIterator iter(scratch_class);
3195   for (; !iter.done(); iter.next()) {
3196     int cur_index = iter.inner_class_info_index();
3197     if (cur_index == 0) {
3198       continue;  // JVM spec. allows null inner class refs so skip it
3199     }
3200     int new_index = find_new_index(cur_index);
3201     if (new_index != 0) {
3202       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3203         ("inner_class_info change: %d to %d", cur_index, new_index));
3204       iter.set_inner_class_info_index(new_index);
3205     }
3206     cur_index = iter.outer_class_info_index();
3207     new_index = find_new_index(cur_index);
3208     if (new_index != 0) {
3209       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3210         ("outer_class_info change: %d to %d", cur_index, new_index));
3211       iter.set_outer_class_info_index(new_index);
3212     }
3213     cur_index = iter.inner_name_index();
3214     new_index = find_new_index(cur_index);
3215     if (new_index != 0) {
3216       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3217         ("inner_name change: %d to %d", cur_index, new_index));
3218       iter.set_inner_name_index(new_index);
3219     }
3220   } // end for each inner class
3221 
3222   // Attach each method in klass to the new constant pool and update
3223   // to use new constant pool indices as needed:
3224   Array<Method*>* methods = scratch_class->methods();
3225   for (i = methods->length() - 1; i >= 0; i--) {
3226     methodHandle method(THREAD, methods->at(i));
3227     method->set_constants(scratch_cp());
3228 
3229     int new_index = find_new_index(method->name_index());
3230     if (new_index != 0) {
3231       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3232         ("method-name_index change: %d to %d", method->name_index(),
3233         new_index));
3234       method->set_name_index(new_index);
3235     }
3236     new_index = find_new_index(method->signature_index());
3237     if (new_index != 0) {
3238       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3239         ("method-signature_index change: %d to %d",
3240         method->signature_index(), new_index));
3241       method->set_signature_index(new_index);
3242     }
3243     new_index = find_new_index(method->generic_signature_index());
3244     if (new_index != 0) {
3245       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3246         ("method-generic_signature_index change: %d to %d",
3247         method->generic_signature_index(), new_index));
3248       method->set_generic_signature_index(new_index);
3249     }
3250 
3251     // Update constant pool indices in the method's checked exception
3252     // table to use new constant indices as needed.
3253     int cext_length = method->checked_exceptions_length();
3254     if (cext_length > 0) {
3255       CheckedExceptionElement * cext_table =
3256         method->checked_exceptions_start();
3257       for (int j = 0; j < cext_length; j++) {
3258         int cur_index = cext_table[j].class_cp_index;
3259         int new_index = find_new_index(cur_index);
3260         if (new_index != 0) {
3261           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3262             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
3263           cext_table[j].class_cp_index = (u2)new_index;
3264         }
3265       } // end for each checked exception table entry
3266     } // end if there are checked exception table entries
3267 
3268     // Update each catch type index in the method's exception table
3269     // to use new constant pool indices as needed. The exception table
3270     // holds quadruple entries of the form:
3271     //   (beg_bci, end_bci, handler_bci, klass_index)
3272 
3273     ExceptionTable ex_table(method());
3274     int ext_length = ex_table.length();
3275 
3276     for (int j = 0; j < ext_length; j ++) {
3277       int cur_index = ex_table.catch_type_index(j);
3278       int new_index = find_new_index(cur_index);
3279       if (new_index != 0) {
3280         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3281           ("ext-klass_index change: %d to %d", cur_index, new_index));
3282         ex_table.set_catch_type_index(j, new_index);
3283       }
3284     } // end for each exception table entry
3285 
3286     // Update constant pool indices in the method's local variable
3287     // table to use new constant indices as needed. The local variable
3288     // table hold sextuple entries of the form:
3289     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3290     int lvt_length = method->localvariable_table_length();
3291     if (lvt_length > 0) {
3292       LocalVariableTableElement * lv_table =
3293         method->localvariable_table_start();
3294       for (int j = 0; j < lvt_length; j++) {
3295         int cur_index = lv_table[j].name_cp_index;
3296         int new_index = find_new_index(cur_index);
3297         if (new_index != 0) {
3298           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3299             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
3300           lv_table[j].name_cp_index = (u2)new_index;
3301         }
3302         cur_index = lv_table[j].descriptor_cp_index;
3303         new_index = find_new_index(cur_index);
3304         if (new_index != 0) {
3305           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3306             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
3307             new_index));
3308           lv_table[j].descriptor_cp_index = (u2)new_index;
3309         }
3310         cur_index = lv_table[j].signature_cp_index;
3311         new_index = find_new_index(cur_index);
3312         if (new_index != 0) {
3313           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3314             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
3315           lv_table[j].signature_cp_index = (u2)new_index;
3316         }
3317       } // end for each local variable table entry
3318     } // end if there are local variable table entries
3319 
3320     rewrite_cp_refs_in_stack_map_table(method, THREAD);
3321   } // end for each method
3322 } // end set_new_constant_pool()
3323 
3324 
3325 // Unevolving classes may point to methods of the_class directly
3326 // from their constant pool caches, itables, and/or vtables. We
3327 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3328 // to fix up these pointers.
3329 
3330 // Adjust cpools and vtables closure
3331 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3332 
3333   // This is a very busy routine. We don't want too much tracing
3334   // printed out.
3335   bool trace_name_printed = false;
3336   InstanceKlass *the_class = InstanceKlass::cast(_the_class_oop);
3337 
3338   // Very noisy: only enable this call if you are trying to determine
3339   // that a specific class gets found by this routine.
3340   // RC_TRACE macro has an embedded ResourceMark
3341   // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
3342   //   ("adjust check: name=%s", k->external_name()));
3343   // trace_name_printed = true;
3344 
3345   // If the class being redefined is java.lang.Object, we need to fix all
3346   // array class vtables also
3347   if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
3348     k->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3349 


3350   } else if (k->oop_is_instance()) {
3351     HandleMark hm(_thread);
3352     InstanceKlass *ik = InstanceKlass::cast(k);
3353 
3354     // HotSpot specific optimization! HotSpot does not currently
3355     // support delegation from the bootstrap class loader to a
3356     // user-defined class loader. This means that if the bootstrap
3357     // class loader is the initiating class loader, then it will also
3358     // be the defining class loader. This also means that classes
3359     // loaded by the bootstrap class loader cannot refer to classes
3360     // loaded by a user-defined class loader. Note: a user-defined
3361     // class loader can delegate to the bootstrap class loader.
3362     //
3363     // If the current class being redefined has a user-defined class
3364     // loader as its defining class loader, then we can skip all
3365     // classes loaded by the bootstrap class loader.
3366     bool is_user_defined =
3367            InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
3368     if (is_user_defined && ik->class_loader() == NULL) {
3369       return;
3370     }
3371 
3372     // Fix the vtable embedded in the_class and subclasses of the_class,
3373     // if one exists. We discard scratch_class and we don't keep an
3374     // InstanceKlass around to hold obsolete methods so we don't have
3375     // any other InstanceKlass embedded vtables to update. The vtable
3376     // holds the Method*s for virtual (but not final) methods.
3377     // Default methods, or concrete methods in interfaces are stored
3378     // in the vtable, so if an interface changes we need to check
3379     // adjust_method_entries() for every InstanceKlass, which will also
3380     // adjust the default method vtable indices.
3381     // We also need to adjust any default method entries that are
3382     // not yet in the vtable, because the vtable setup is in progress.
3383     // This must be done after we adjust the default_methods and
3384     // default_vtable_indices for methods already in the vtable.
3385     // If redefining Unsafe, walk all the vtables looking for entries.
3386     if (ik->vtable_length() > 0 && (_the_class_oop->is_interface()
3387         || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3388         || ik->is_subtype_of(_the_class_oop))) {
3389       // ik->vtable() creates a wrapper object; rm cleans it up
3390       ResourceMark rm(_thread);
3391 
3392       ik->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3393       ik->adjust_default_methods(the_class, &trace_name_printed);





3394     }
3395 
3396     // If the current class has an itable and we are either redefining an
3397     // interface or if the current class is a subclass of the_class, then
3398     // we potentially have to fix the itable. If we are redefining an
3399     // interface, then we have to call adjust_method_entries() for
3400     // every InstanceKlass that has an itable since there isn't a
3401     // subclass relationship between an interface and an InstanceKlass.
3402     // If redefining Unsafe, walk all the itables looking for entries.
3403     if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
3404         || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3405         || ik->is_subclass_of(_the_class_oop))) {
3406       // ik->itable() creates a wrapper object; rm cleans it up
3407       ResourceMark rm(_thread);
3408 
3409       ik->itable()->adjust_method_entries(the_class, &trace_name_printed);


3410     }
3411 
3412     // The constant pools in other classes (other_cp) can refer to
3413     // methods in the_class. We have to update method information in
3414     // other_cp's cache. If other_cp has a previous version, then we
3415     // have to repeat the process for each previous version. The
3416     // constant pool cache holds the Method*s for non-virtual
3417     // methods and for virtual, final methods.
3418     //
3419     // Special case: if the current class is the_class, then new_cp
3420     // has already been attached to the_class and old_cp has already
3421     // been added as a previous version. The new_cp doesn't have any
3422     // cached references to old methods so it doesn't need to be
3423     // updated. We can simply start with the previous version(s) in
3424     // that case.
3425     constantPoolHandle other_cp;
3426     ConstantPoolCache* cp_cache;
3427 
3428     if (ik != _the_class_oop) {
3429       // this klass' constant pool cache may need adjustment
3430       other_cp = constantPoolHandle(ik->constants());
3431       cp_cache = other_cp->cache();
3432       if (cp_cache != NULL) {
3433         cp_cache->adjust_method_entries(the_class, &trace_name_printed);



3434       }
3435     }
3436 
3437     // the previous versions' constant pool caches may need adjustment
3438     for (InstanceKlass* pv_node = ik->previous_versions();
3439          pv_node != NULL;
3440          pv_node = pv_node->previous_versions()) {
3441       cp_cache = pv_node->constants()->cache();
3442       if (cp_cache != NULL) {
3443         cp_cache->adjust_method_entries(_matching_old_methods,
3444                                         _matching_new_methods,
3445                                         _matching_methods_length,
3446                                         &trace_name_printed);
3447       }
3448     }
3449   }
3450 }
3451 
3452 // Clean method data for this class
3453 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3454   if (k->oop_is_instance()) {
3455     InstanceKlass *ik = InstanceKlass::cast(k);
3456     // Clean MethodData of this class's methods so they don't refer to
3457     // old methods that are no longer running.
3458     Array<Method*>* methods = ik->methods();
3459     int num_methods = methods->length();
3460     for (int index = 0; index < num_methods; ++index) {
3461       if (methods->at(index)->method_data() != NULL) {
3462         methods->at(index)->method_data()->clean_weak_method_links();
3463       }
3464     }
3465   }
3466 }
3467 
3468 void VM_RedefineClasses::update_jmethod_ids() {
3469   for (int j = 0; j < _matching_methods_length; ++j) {
3470     Method* old_method = _matching_old_methods[j];
3471     jmethodID jmid = old_method->find_jmethod_id_or_null();
3472     if (jmid != NULL) {
3473       // There is a jmethodID, change it to point to the new method
3474       methodHandle new_method_h(_matching_new_methods[j]);
3475       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3476       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3477              "should be replaced");
3478     }
3479   }
3480 }
3481 
3482 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3483   int emcp_method_count = 0;
3484   int obsolete_count = 0;
3485   int old_index = 0;
3486   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3487     Method* old_method = _matching_old_methods[j];
3488     Method* new_method = _matching_new_methods[j];
3489     Method* old_array_method;
3490 
3491     // Maintain an old_index into the _old_methods array by skipping
3492     // deleted methods
3493     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3494       ++old_index;
3495     }
3496 
3497     if (MethodComparator::methods_EMCP(old_method, new_method)) {
3498       // The EMCP definition from JSR-163 requires the bytecodes to be
3499       // the same with the exception of constant pool indices which may
3500       // differ. However, the constants referred to by those indices
3501       // must be the same.
3502       //
3503       // We use methods_EMCP() for comparison since constant pool
3504       // merging can remove duplicate constant pool entries that were
3505       // present in the old method and removed from the rewritten new
3506       // method. A faster binary comparison function would consider the
3507       // old and new methods to be different when they are actually
3508       // EMCP.
3509       //
3510       // The old and new methods are EMCP and you would think that we
3511       // could get rid of one of them here and now and save some space.
3512       // However, the concept of EMCP only considers the bytecodes and
3513       // the constant pool entries in the comparison. Other things,
3514       // e.g., the line number table (LNT) or the local variable table
3515       // (LVT) don't count in the comparison. So the new (and EMCP)
3516       // method can have a new LNT that we need so we can't just
3517       // overwrite the new method with the old method.
3518       //
3519       // When this routine is called, we have already attached the new
3520       // methods to the_class so the old methods are effectively
3521       // overwritten. However, if an old method is still executing,
3522       // then the old method cannot be collected until sometime after
3523       // the old method call has returned. So the overwriting of old
3524       // methods by new methods will save us space except for those
3525       // (hopefully few) old methods that are still executing.
3526       //
3527       // A method refers to a ConstMethod* and this presents another
3528       // possible avenue to space savings. The ConstMethod* in the
3529       // new method contains possibly new attributes (LNT, LVT, etc).
3530       // At first glance, it seems possible to save space by replacing
3531       // the ConstMethod* in the old method with the ConstMethod*
3532       // from the new method. The old and new methods would share the
3533       // same ConstMethod* and we would save the space occupied by
3534       // the old ConstMethod*. However, the ConstMethod* contains
3535       // a back reference to the containing method. Sharing the
3536       // ConstMethod* between two methods could lead to confusion in
3537       // the code that uses the back reference. This would lead to
3538       // brittle code that could be broken in non-obvious ways now or
3539       // in the future.
3540       //
3541       // Another possibility is to copy the ConstMethod* from the new
3542       // method to the old method and then overwrite the new method with
3543       // the old method. Since the ConstMethod* contains the bytecodes
3544       // for the method embedded in the oop, this option would change
3545       // the bytecodes out from under any threads executing the old
3546       // method and make the thread's bcp invalid. Since EMCP requires
3547       // that the bytecodes be the same modulo constant pool indices, it
3548       // is straight forward to compute the correct new bcp in the new
3549       // ConstMethod* from the old bcp in the old ConstMethod*. The
3550       // time consuming part would be searching all the frames in all
3551       // of the threads to find all of the calls to the old method.
3552       //
3553       // It looks like we will have to live with the limited savings
3554       // that we get from effectively overwriting the old methods
3555       // when the new methods are attached to the_class.
3556 
3557       // Count number of methods that are EMCP.  The method will be marked
3558       // old but not obsolete if it is EMCP.
3559       emcp_method_count++;
3560 
3561       // An EMCP method is _not_ obsolete. An obsolete method has a
3562       // different jmethodID than the current method. An EMCP method
3563       // has the same jmethodID as the current method. Having the
3564       // same jmethodID for all EMCP versions of a method allows for
3565       // a consistent view of the EMCP methods regardless of which
3566       // EMCP method you happen to have in hand. For example, a
3567       // breakpoint set in one EMCP method will work for all EMCP
3568       // versions of the method including the current one.
3569     } else {
3570       // mark obsolete methods as such
3571       old_method->set_is_obsolete();
3572       obsolete_count++;
3573 
3574       // obsolete methods need a unique idnum so they become new entries in
3575       // the jmethodID cache in InstanceKlass
3576       assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3577       u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
3578       if (num != ConstMethod::UNSET_IDNUM) {
3579         old_method->set_method_idnum(num);
3580       }
3581 
3582       // With tracing we try not to "yack" too much. The position of
3583       // this trace assumes there are fewer obsolete methods than
3584       // EMCP methods.
3585       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
3586         old_method->name()->as_C_string(),
3587         old_method->signature()->as_C_string()));
3588     }
3589     old_method->set_is_old();
3590   }
3591   for (int i = 0; i < _deleted_methods_length; ++i) {
3592     Method* old_method = _deleted_methods[i];
3593 
3594     assert(!old_method->has_vtable_index(),
3595            "cannot delete methods with vtable entries");;
3596 
3597     // Mark all deleted methods as old, obsolete and deleted
3598     old_method->set_is_deleted();
3599     old_method->set_is_old();
3600     old_method->set_is_obsolete();
3601     ++obsolete_count;
3602     // With tracing we try not to "yack" too much. The position of
3603     // this trace assumes there are fewer obsolete methods than
3604     // EMCP methods.
3605     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
3606                           old_method->name()->as_C_string(),
3607                           old_method->signature()->as_C_string()));
3608   }
3609   assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3610     "sanity check");
3611   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count,
3612     obsolete_count));
3613   return emcp_method_count;
3614 }
3615 
3616 // This internal class transfers the native function registration from old methods
3617 // to new methods.  It is designed to handle both the simple case of unchanged
3618 // native methods and the complex cases of native method prefixes being added and/or
3619 // removed.
3620 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3621 //
3622 // This class is used after the new methods have been installed in "the_class".
3623 //
3624 // So, for example, the following must be handled.  Where 'm' is a method and
3625 // a number followed by an underscore is a prefix.
3626 //
3627 //                                      Old Name    New Name
3628 // Simple transfer to new method        m       ->  m
3629 // Add prefix                           m       ->  1_m
3630 // Remove prefix                        1_m     ->  m
3631 // Simultaneous add of prefixes         m       ->  3_2_1_m
3632 // Simultaneous removal of prefixes     3_2_1_m ->  m
3633 // Simultaneous add and remove          1_m     ->  2_m
3634 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
3635 //
3636 class TransferNativeFunctionRegistration {
3637  private:
3638   instanceKlassHandle the_class;
3639   int prefix_count;
3640   char** prefixes;
3641 
3642   // Recursively search the binary tree of possibly prefixed method names.
3643   // Iteration could be used if all agents were well behaved. Full tree walk is
3644   // more resilent to agents not cleaning up intermediate methods.
3645   // Branch at each depth in the binary tree is:
3646   //    (1) without the prefix.
3647   //    (2) with the prefix.
3648   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3649   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3650                                      Symbol* signature) {
3651     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3652     if (name_symbol != NULL) {
3653       Method* method = the_class()->lookup_method(name_symbol, signature);
3654       if (method != NULL) {
3655         // Even if prefixed, intermediate methods must exist.
3656         if (method->is_native()) {
3657           // Wahoo, we found a (possibly prefixed) version of the method, return it.
3658           return method;
3659         }
3660         if (depth < prefix_count) {
3661           // Try applying further prefixes (other than this one).
3662           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3663           if (method != NULL) {
3664             return method; // found
3665           }
3666 
3667           // Try adding this prefix to the method name and see if it matches
3668           // another method name.
3669           char* prefix = prefixes[depth];
3670           size_t prefix_len = strlen(prefix);
3671           size_t trial_len = name_len + prefix_len;
3672           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3673           strcpy(trial_name_str, prefix);
3674           strcat(trial_name_str, name_str);
3675           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3676                                             signature);
3677           if (method != NULL) {
3678             // If found along this branch, it was prefixed, mark as such
3679             method->set_is_prefixed_native();
3680             return method; // found
3681           }
3682         }
3683       }
3684     }
3685     return NULL;  // This whole branch bore nothing
3686   }
3687 
3688   // Return the method name with old prefixes stripped away.
3689   char* method_name_without_prefixes(Method* method) {
3690     Symbol* name = method->name();
3691     char* name_str = name->as_utf8();
3692 
3693     // Old prefixing may be defunct, strip prefixes, if any.
3694     for (int i = prefix_count-1; i >= 0; i--) {
3695       char* prefix = prefixes[i];
3696       size_t prefix_len = strlen(prefix);
3697       if (strncmp(prefix, name_str, prefix_len) == 0) {
3698         name_str += prefix_len;
3699       }
3700     }
3701     return name_str;
3702   }
3703 
3704   // Strip any prefixes off the old native method, then try to find a
3705   // (possibly prefixed) new native that matches it.
3706   Method* strip_and_search_for_new_native(Method* method) {
3707     ResourceMark rm;
3708     char* name_str = method_name_without_prefixes(method);
3709     return search_prefix_name_space(0, name_str, strlen(name_str),
3710                                     method->signature());
3711   }
3712 
3713  public:
3714 
3715   // Construct a native method transfer processor for this class.
3716   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
3717     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3718 
3719     the_class = _the_class;
3720     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3721   }
3722 
3723   // Attempt to transfer any of the old or deleted methods that are native
3724   void transfer_registrations(Method** old_methods, int methods_length) {
3725     for (int j = 0; j < methods_length; j++) {
3726       Method* old_method = old_methods[j];
3727 
3728       if (old_method->is_native() && old_method->has_native_function()) {
3729         Method* new_method = strip_and_search_for_new_native(old_method);
3730         if (new_method != NULL) {
3731           // Actually set the native function in the new method.
3732           // Redefine does not send events (except CFLH), certainly not this
3733           // behind the scenes re-registration.
3734           new_method->set_native_function(old_method->native_function(),
3735                               !Method::native_bind_event_is_interesting);
3736         }
3737       }
3738     }
3739   }
3740 };
3741 
3742 // Don't lose the association between a native method and its JNI function.
3743 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
3744   TransferNativeFunctionRegistration transfer(the_class);
3745   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3746   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3747 }
3748 
3749 // Deoptimize all compiled code that depends on this class.
3750 //
3751 // If the can_redefine_classes capability is obtained in the onload
3752 // phase then the compiler has recorded all dependencies from startup.
3753 // In that case we need only deoptimize and throw away all compiled code
3754 // that depends on the class.
3755 //
3756 // If can_redefine_classes is obtained sometime after the onload
3757 // phase then the dependency information may be incomplete. In that case
3758 // the first call to RedefineClasses causes all compiled code to be
3759 // thrown away. As can_redefine_classes has been obtained then
3760 // all future compilations will record dependencies so second and
3761 // subsequent calls to RedefineClasses need only throw away code
3762 // that depends on the class.
3763 //
3764 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
3765   assert_locked_or_safepoint(Compile_lock);
3766 
3767   // All dependencies have been recorded from startup or this is a second or
3768   // subsequent use of RedefineClasses
3769   if (JvmtiExport::all_dependencies_are_recorded()) {
3770     CodeCache::flush_evol_dependents_on(k_h);
3771   } else {
3772     CodeCache::mark_all_nmethods_for_deoptimization();
3773 
3774     ResourceMark rm(THREAD);
3775     DeoptimizationMarker dm;
3776 
3777     // Deoptimize all activations depending on marked nmethods
3778     Deoptimization::deoptimize_dependents();
3779 
3780     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
3781     CodeCache::make_marked_nmethods_not_entrant();
3782 
3783     // From now on we know that the dependency information is complete
3784     JvmtiExport::set_all_dependencies_are_recorded(true);
3785   }
3786 }
3787 
3788 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3789   Method* old_method;
3790   Method* new_method;
3791 
3792   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3793   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3794   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3795   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3796 
3797   _matching_methods_length = 0;
3798   _deleted_methods_length  = 0;
3799   _added_methods_length    = 0;
3800 
3801   int nj = 0;
3802   int oj = 0;
3803   while (true) {
3804     if (oj >= _old_methods->length()) {
3805       if (nj >= _new_methods->length()) {
3806         break; // we've looked at everything, done
3807       }
3808       // New method at the end
3809       new_method = _new_methods->at(nj);
3810       _added_methods[_added_methods_length++] = new_method;
3811       ++nj;
3812     } else if (nj >= _new_methods->length()) {
3813       // Old method, at the end, is deleted
3814       old_method = _old_methods->at(oj);
3815       _deleted_methods[_deleted_methods_length++] = old_method;
3816       ++oj;
3817     } else {
3818       old_method = _old_methods->at(oj);
3819       new_method = _new_methods->at(nj);
3820       if (old_method->name() == new_method->name()) {
3821         if (old_method->signature() == new_method->signature()) {
3822           _matching_old_methods[_matching_methods_length  ] = old_method;
3823           _matching_new_methods[_matching_methods_length++] = new_method;
3824           ++nj;
3825           ++oj;
3826         } else {
3827           // added overloaded have already been moved to the end,
3828           // so this is a deleted overloaded method
3829           _deleted_methods[_deleted_methods_length++] = old_method;
3830           ++oj;
3831         }
3832       } else { // names don't match
3833         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3834           // new method
3835           _added_methods[_added_methods_length++] = new_method;
3836           ++nj;
3837         } else {
3838           // deleted method
3839           _deleted_methods[_deleted_methods_length++] = old_method;
3840           ++oj;
3841         }
3842       }
3843     }
3844   }
3845   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3846   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3847 }
3848 
3849 
3850 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
3851                                           instanceKlassHandle scratch_class) {
3852   // Swap annotation fields values
3853   Annotations* old_annotations = the_class->annotations();
3854   the_class->set_annotations(scratch_class->annotations());
3855   scratch_class->set_annotations(old_annotations);
3856 }
3857 
3858 
3859 // Install the redefinition of a class:
3860 //    - house keeping (flushing breakpoints and caches, deoptimizing
3861 //      dependent compiled code)
3862 //    - replacing parts in the_class with parts from scratch_class
3863 //    - adding a weak reference to track the obsolete but interesting
3864 //      parts of the_class
3865 //    - adjusting constant pool caches and vtables in other classes
3866 //      that refer to methods in the_class. These adjustments use the
3867 //      ClassLoaderDataGraph::classes_do() facility which only allows
3868 //      a helper method to be specified. The interesting parameters
3869 //      that we would like to pass to the helper method are saved in
3870 //      static global fields in the VM operation.
3871 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3872        Klass* scratch_class_oop, TRAPS) {
3873 
3874   HandleMark hm(THREAD);   // make sure handles from this call are freed
3875   RC_TIMER_START(_timer_rsc_phase1);
3876 
3877   instanceKlassHandle scratch_class(scratch_class_oop);
3878 
3879   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3880   Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
3881   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3882 
3883   // Remove all breakpoints in methods of this class
3884   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3885   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3886 
3887   // Deoptimize all compiled code that depends on this class
3888   flush_dependent_code(the_class, THREAD);
3889 
3890   _old_methods = the_class->methods();
3891   _new_methods = scratch_class->methods();
3892   _the_class_oop = the_class_oop;
3893   compute_added_deleted_matching_methods();
3894   update_jmethod_ids();
3895 
3896   // Attach new constant pool to the original klass. The original
3897   // klass still refers to the old constant pool (for now).
3898   scratch_class->constants()->set_pool_holder(the_class());
3899 
3900 #if 0
3901   // In theory, with constant pool merging in place we should be able
3902   // to save space by using the new, merged constant pool in place of
3903   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3904   // the klass version we are replacing now and any constant pool(s) in
3905   // previous versions of klass. Nice theory, doesn't work in practice.
3906   // When this code is enabled, even simple programs throw NullPointer
3907   // exceptions. I'm guessing that this is caused by some constant pool
3908   // cache difference between the new, merged constant pool and the
3909   // constant pool that was just being used by the klass. I'm keeping
3910   // this code around to archive the idea, but the code has to remain
3911   // disabled for now.
3912 
3913   // Attach each old method to the new constant pool. This can be
3914   // done here since we are past the bytecode verification and
3915   // constant pool optimization phases.
3916   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3917     Method* method = _old_methods->at(i);
3918     method->set_constants(scratch_class->constants());
3919   }
3920 
3921   {
3922     // walk all previous versions of the klass
3923     InstanceKlass *ik = (InstanceKlass *)the_class();
3924     PreviousVersionWalker pvw(ik);
3925     instanceKlassHandle ikh;
3926     do {
3927       ikh = pvw.next_previous_version();
3928       if (!ikh.is_null()) {
3929         ik = ikh();
3930 
3931         // attach previous version of klass to the new constant pool
3932         ik->set_constants(scratch_class->constants());
3933 
3934         // Attach each method in the previous version of klass to the
3935         // new constant pool
3936         Array<Method*>* prev_methods = ik->methods();
3937         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3938           Method* method = prev_methods->at(i);
3939           method->set_constants(scratch_class->constants());
3940         }
3941       }
3942     } while (!ikh.is_null());
3943   }
3944 #endif
3945 
3946   // Replace methods and constantpool
3947   the_class->set_methods(_new_methods);
3948   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3949                                           // and to be able to undo operation easily.
3950 
3951   ConstantPool* old_constants = the_class->constants();
3952   the_class->set_constants(scratch_class->constants());
3953   scratch_class->set_constants(old_constants);  // See the previous comment.
3954 #if 0
3955   // We are swapping the guts of "the new class" with the guts of "the
3956   // class". Since the old constant pool has just been attached to "the
3957   // new class", it seems logical to set the pool holder in the old
3958   // constant pool also. However, doing this will change the observable
3959   // class hierarchy for any old methods that are still executing. A
3960   // method can query the identity of its "holder" and this query uses
3961   // the method's constant pool link to find the holder. The change in
3962   // holding class from "the class" to "the new class" can confuse
3963   // things.
3964   //
3965   // Setting the old constant pool's holder will also cause
3966   // verification done during vtable initialization below to fail.
3967   // During vtable initialization, the vtable's class is verified to be
3968   // a subtype of the method's holder. The vtable's class is "the
3969   // class" and the method's holder is gotten from the constant pool
3970   // link in the method itself. For "the class"'s directly implemented
3971   // methods, the method holder is "the class" itself (as gotten from
3972   // the new constant pool). The check works fine in this case. The
3973   // check also works fine for methods inherited from super classes.
3974   //
3975   // Miranda methods are a little more complicated. A miranda method is
3976   // provided by an interface when the class implementing the interface
3977   // does not provide its own method.  These interfaces are implemented
3978   // internally as an InstanceKlass. These special instanceKlasses
3979   // share the constant pool of the class that "implements" the
3980   // interface. By sharing the constant pool, the method holder of a
3981   // miranda method is the class that "implements" the interface. In a
3982   // non-redefine situation, the subtype check works fine. However, if
3983   // the old constant pool's pool holder is modified, then the check
3984   // fails because there is no class hierarchy relationship between the
3985   // vtable's class and "the new class".
3986 
3987   old_constants->set_pool_holder(scratch_class());
3988 #endif
3989 
3990   // track number of methods that are EMCP for add_previous_version() call below
3991   int emcp_method_count = check_methods_and_mark_as_obsolete();
3992   transfer_old_native_function_registrations(the_class);
3993 
3994   // The class file bytes from before any retransformable agents mucked
3995   // with them was cached on the scratch class, move to the_class.
3996   // Note: we still want to do this if nothing needed caching since it
3997   // should get cleared in the_class too.
3998   if (the_class->get_cached_class_file_bytes() == 0) {
3999     // the_class doesn't have a cache yet so copy it
4000     the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4001   }
4002 #ifndef PRODUCT
4003   else {
4004     assert(the_class->get_cached_class_file_bytes() ==
4005       scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
4006     assert(the_class->get_cached_class_file_len() ==
4007       scratch_class->get_cached_class_file_len(), "cache lens must match");
4008   }
4009 #endif
4010 
4011   // NULL out in scratch class to not delete twice.  The class to be redefined
4012   // always owns these bytes.
4013   scratch_class->set_cached_class_file(NULL);
4014 
4015   // Replace inner_classes
4016   Array<u2>* old_inner_classes = the_class->inner_classes();
4017   the_class->set_inner_classes(scratch_class->inner_classes());
4018   scratch_class->set_inner_classes(old_inner_classes);
4019 
4020   // Initialize the vtable and interface table after
4021   // methods have been rewritten
4022   {
4023     ResourceMark rm(THREAD);
4024     // no exception should happen here since we explicitly
4025     // do not check loader constraints.
4026     // compare_and_normalize_class_versions has already checked:
4027     //  - classloaders unchanged, signatures unchanged
4028     //  - all instanceKlasses for redefined classes reused & contents updated
4029     the_class->vtable()->initialize_vtable(false, THREAD);
4030     the_class->itable()->initialize_itable(false, THREAD);
4031     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4032   }
4033 
4034   // Leave arrays of jmethodIDs and itable index cache unchanged
4035 
4036   // Copy the "source file name" attribute from new class version
4037   the_class->set_source_file_name_index(
4038     scratch_class->source_file_name_index());
4039 
4040   // Copy the "source debug extension" attribute from new class version
4041   the_class->set_source_debug_extension(
4042     scratch_class->source_debug_extension(),
4043     scratch_class->source_debug_extension() == NULL ? 0 :
4044     (int)strlen(scratch_class->source_debug_extension()));
4045 
4046   // Use of javac -g could be different in the old and the new
4047   if (scratch_class->access_flags().has_localvariable_table() !=
4048       the_class->access_flags().has_localvariable_table()) {
4049 
4050     AccessFlags flags = the_class->access_flags();
4051     if (scratch_class->access_flags().has_localvariable_table()) {
4052       flags.set_has_localvariable_table();
4053     } else {
4054       flags.clear_has_localvariable_table();
4055     }
4056     the_class->set_access_flags(flags);
4057   }
4058 
4059   swap_annotations(the_class, scratch_class);
4060 
4061   // Replace minor version number of class file
4062   u2 old_minor_version = the_class->minor_version();
4063   the_class->set_minor_version(scratch_class->minor_version());
4064   scratch_class->set_minor_version(old_minor_version);
4065 
4066   // Replace major version number of class file
4067   u2 old_major_version = the_class->major_version();
4068   the_class->set_major_version(scratch_class->major_version());
4069   scratch_class->set_major_version(old_major_version);
4070 
4071   // Replace CP indexes for class and name+type of enclosing method
4072   u2 old_class_idx  = the_class->enclosing_method_class_index();
4073   u2 old_method_idx = the_class->enclosing_method_method_index();
4074   the_class->set_enclosing_method_indices(
4075     scratch_class->enclosing_method_class_index(),
4076     scratch_class->enclosing_method_method_index());
4077   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4078 
4079   the_class->set_has_been_redefined();
4080 
4081   // keep track of previous versions of this class
4082   the_class->add_previous_version(scratch_class, emcp_method_count);
4083 
4084   RC_TIMER_STOP(_timer_rsc_phase1);
4085   RC_TIMER_START(_timer_rsc_phase2);
4086 
4087   // Adjust constantpool caches and vtables for all classes
4088   // that reference methods of the evolved class.
4089   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4090   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4091 
4092   // JSR-292 support
4093   MemberNameTable* mnt = the_class->member_names();
4094   if (mnt != NULL) {
4095     bool trace_name_printed = false;
4096     mnt->adjust_method_entries(_matching_old_methods,
4097                                _matching_new_methods,
4098                                _matching_methods_length,
4099                                &trace_name_printed);
4100   }
4101 
4102   // Fix Resolution Error table also to remove old constant pools
4103   SystemDictionary::delete_resolution_error(old_constants);
4104 
4105   if (the_class->oop_map_cache() != NULL) {
4106     // Flush references to any obsolete methods from the oop map cache
4107     // so that obsolete methods are not pinned.
4108     the_class->oop_map_cache()->flush_obsolete_entries();
4109   }
4110 
4111   // increment the classRedefinedCount field in the_class and in any
4112   // direct and indirect subclasses of the_class
4113   increment_class_counter((InstanceKlass *)the_class(), THREAD);
4114 
4115   // RC_TRACE macro has an embedded ResourceMark
4116   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
4117     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4118     the_class->external_name(),
4119     java_lang_Class::classRedefinedCount(the_class_mirror),
4120     os::available_memory() >> 10));
4121 
4122   RC_TIMER_STOP(_timer_rsc_phase2);
4123 } // end redefine_single_class()
4124 
4125 
4126 // Increment the classRedefinedCount field in the specific InstanceKlass
4127 // and in all direct and indirect subclasses.
4128 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4129   oop class_mirror = ik->java_mirror();
4130   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4131   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4132   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4133 
4134   if (class_oop != _the_class_oop) {
4135     // _the_class_oop count is printed at end of redefine_single_class()
4136     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
4137       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
4138   }
4139 
4140   for (Klass *subk = ik->subklass(); subk != NULL;
4141        subk = subk->next_sibling()) {
4142     if (subk->oop_is_instance()) {
4143       // Only update instanceKlasses
4144       InstanceKlass *subik = (InstanceKlass*)subk;
4145       // recursively do subclasses of the current subclass
4146       increment_class_counter(subik, THREAD);
4147     }
4148   }
4149 }
4150 
4151 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4152   bool no_old_methods = true;  // be optimistic
4153 
4154   // Both array and instance classes have vtables.
4155   // a vtable should never contain old or obsolete methods
4156   ResourceMark rm(_thread);
4157   if (k->vtable_length() > 0 &&
4158       !k->vtable()->check_no_old_or_obsolete_entries()) {
4159     if (RC_TRACE_ENABLED(0x00004000)) {
4160       RC_TRACE_WITH_THREAD(0x00004000, _thread,
4161         ("klassVtable::check_no_old_or_obsolete_entries failure"
4162          " -- OLD or OBSOLETE method found -- class: %s",
4163          k->signature_name()));
4164       k->vtable()->dump_vtable();
4165     }
4166     no_old_methods = false;
4167   }
4168 
4169   if (k->oop_is_instance()) {
4170     HandleMark hm(_thread);
4171     InstanceKlass *ik = InstanceKlass::cast(k);
4172 
4173     // an itable should never contain old or obsolete methods
4174     if (ik->itable_length() > 0 &&
4175         !ik->itable()->check_no_old_or_obsolete_entries()) {
4176       if (RC_TRACE_ENABLED(0x00004000)) {
4177         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4178           ("klassItable::check_no_old_or_obsolete_entries failure"
4179            " -- OLD or OBSOLETE method found -- class: %s",
4180            ik->signature_name()));
4181         ik->itable()->dump_itable();
4182       }
4183       no_old_methods = false;
4184     }
4185 
4186     // the constant pool cache should never contain non-deleted old or obsolete methods
4187     if (ik->constants() != NULL &&
4188         ik->constants()->cache() != NULL &&
4189         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4190       if (RC_TRACE_ENABLED(0x00004000)) {
4191         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4192           ("cp-cache::check_no_old_or_obsolete_entries failure"
4193            " -- OLD or OBSOLETE method found -- class: %s",
4194            ik->signature_name()));
4195         ik->constants()->cache()->dump_cache();
4196       }
4197       no_old_methods = false;
4198     }
4199   }
4200 
4201   // print and fail guarantee if old methods are found.
4202   if (!no_old_methods) {
4203     if (RC_TRACE_ENABLED(0x00004000)) {
4204       dump_methods();
4205     } else {
4206       tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
4207         "to see more info about the following guarantee() failure.");
4208     }
4209     guarantee(false, "OLD and/or OBSOLETE method(s) found");
4210   }
4211 }
4212 
4213 
4214 void VM_RedefineClasses::dump_methods() {
4215   int j;
4216   RC_TRACE(0x00004000, ("_old_methods --"));
4217   for (j = 0; j < _old_methods->length(); ++j) {
4218     Method* m = _old_methods->at(j);
4219     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4220     m->access_flags().print_on(tty);
4221     tty->print(" --  ");
4222     m->print_name(tty);
4223     tty->cr();
4224   }
4225   RC_TRACE(0x00004000, ("_new_methods --"));
4226   for (j = 0; j < _new_methods->length(); ++j) {
4227     Method* m = _new_methods->at(j);
4228     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4229     m->access_flags().print_on(tty);
4230     tty->print(" --  ");
4231     m->print_name(tty);
4232     tty->cr();
4233   }
4234   RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
4235   for (j = 0; j < _matching_methods_length; ++j) {
4236     Method* m = _matching_old_methods[j];
4237     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4238     m->access_flags().print_on(tty);
4239     tty->print(" --  ");
4240     m->print_name(tty);
4241     tty->cr();
4242     m = _matching_new_methods[j];
4243     RC_TRACE_NO_CR(0x00004000, ("      (%5d)  ", m->vtable_index()));
4244     m->access_flags().print_on(tty);
4245     tty->cr();
4246   }
4247   RC_TRACE(0x00004000, ("_deleted_methods --"));
4248   for (j = 0; j < _deleted_methods_length; ++j) {
4249     Method* m = _deleted_methods[j];
4250     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4251     m->access_flags().print_on(tty);
4252     tty->print(" --  ");
4253     m->print_name(tty);
4254     tty->cr();
4255   }
4256   RC_TRACE(0x00004000, ("_added_methods --"));
4257   for (j = 0; j < _added_methods_length; ++j) {
4258     Method* m = _added_methods[j];
4259     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4260     m->access_flags().print_on(tty);
4261     tty->print(" --  ");
4262     m->print_name(tty);
4263     tty->cr();
4264   }
4265 }
--- EOF ---