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 "oops/oop.inline.hpp"
  40 #include "prims/jvmtiImpl.hpp"
  41 #include "prims/jvmtiRedefineClasses.hpp"
  42 #include "prims/methodComparator.hpp"
  43 #include "runtime/deoptimization.hpp"
  44 #include "runtime/relocator.hpp"
  45 #include "utilities/bitMap.inline.hpp"
  46 
  47 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  48 
  49 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
  50 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
  51 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
  52 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
  53 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
  54 Method**  VM_RedefineClasses::_added_methods        = NULL;
  55 int         VM_RedefineClasses::_matching_methods_length = 0;
  56 int         VM_RedefineClasses::_deleted_methods_length  = 0;
  57 int         VM_RedefineClasses::_added_methods_length    = 0;
  58 Klass*      VM_RedefineClasses::_the_class_oop = NULL;
  59 
  60 
  61 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
  62                                        const jvmtiClassDefinition *class_defs,
  63                                        JvmtiClassLoadKind class_load_kind) {
  64   _class_count = class_count;
  65   _class_defs = class_defs;
  66   _class_load_kind = class_load_kind;
  67   _res = JVMTI_ERROR_NONE;
  68 }
  69 
  70 bool VM_RedefineClasses::doit_prologue() {
  71   if (_class_count == 0) {
  72     _res = JVMTI_ERROR_NONE;
  73     return false;
  74   }
  75   if (_class_defs == NULL) {
  76     _res = JVMTI_ERROR_NULL_POINTER;
  77     return false;
  78   }
  79   for (int i = 0; i < _class_count; i++) {
  80     if (_class_defs[i].klass == NULL) {
  81       _res = JVMTI_ERROR_INVALID_CLASS;
  82       return false;
  83     }
  84     if (_class_defs[i].class_byte_count == 0) {
  85       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
  86       return false;
  87     }
  88     if (_class_defs[i].class_bytes == NULL) {
  89       _res = JVMTI_ERROR_NULL_POINTER;
  90       return false;
  91     }
  92   }
  93 
  94   // Start timer after all the sanity checks; not quite accurate, but
  95   // better than adding a bunch of stop() calls.
  96   RC_TIMER_START(_timer_vm_op_prologue);
  97 
  98   // We first load new class versions in the prologue, because somewhere down the
  99   // call chain it is required that the current thread is a Java thread.
 100   _res = load_new_class_versions(Thread::current());
 101   if (_res != JVMTI_ERROR_NONE) {
 102     // free any successfully created classes, since none are redefined
 103     for (int i = 0; i < _class_count; i++) {
 104       if (_scratch_classes[i] != NULL) {
 105         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
 106         // Free the memory for this class at class unloading time.  Not before
 107         // because CMS might think this is still live.
 108         cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
 109       }
 110     }
 111     // Free os::malloc allocated memory in load_new_class_version.
 112     os::free(_scratch_classes);
 113     RC_TIMER_STOP(_timer_vm_op_prologue);
 114     return false;
 115   }
 116 
 117   RC_TIMER_STOP(_timer_vm_op_prologue);
 118   return true;
 119 }
 120 
 121 void VM_RedefineClasses::doit() {
 122   Thread *thread = Thread::current();
 123 
 124   if (UseSharedSpaces) {
 125     // Sharing is enabled so we remap the shared readonly space to
 126     // shared readwrite, private just in case we need to redefine
 127     // a shared class. We do the remap during the doit() phase of
 128     // the safepoint to be safer.
 129     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
 130       RC_TRACE_WITH_THREAD(0x00000001, thread,
 131         ("failed to remap shared readonly space to readwrite, private"));
 132       _res = JVMTI_ERROR_INTERNAL;
 133       return;
 134     }
 135   }
 136 
 137   // Mark methods seen on stack and everywhere else so old methods are not
 138   // cleaned up if they're on the stack.
 139   MetadataOnStackMark md_on_stack(true);
 140   HandleMark hm(thread);   // make sure any handles created are deleted
 141                            // before the stack walk again.
 142 
 143   for (int i = 0; i < _class_count; i++) {
 144     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
 145   }
 146 
 147   // Clean out MethodData pointing to old Method*
 148   // Have to do this after all classes are redefined and all methods that
 149   // are redefined are marked as old.
 150   MethodDataCleaner clean_weak_method_links;
 151   ClassLoaderDataGraph::classes_do(&clean_weak_method_links);
 152 
 153   // Disable any dependent concurrent compilations
 154   SystemDictionary::notice_modification();
 155 
 156   // Set flag indicating that some invariants are no longer true.
 157   // See jvmtiExport.hpp for detailed explanation.
 158   JvmtiExport::set_has_redefined_a_class();
 159 
 160   // check_class() is optionally called for product bits, but is
 161   // always called for non-product bits.
 162 #ifdef PRODUCT
 163   if (RC_TRACE_ENABLED(0x00004000)) {
 164 #endif
 165     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
 166     CheckClass check_class(thread);
 167     ClassLoaderDataGraph::classes_do(&check_class);
 168 #ifdef PRODUCT
 169   }
 170 #endif
 171 }
 172 
 173 void VM_RedefineClasses::doit_epilogue() {
 174   // Free os::malloc allocated memory.
 175   os::free(_scratch_classes);
 176 
 177   if (RC_TRACE_ENABLED(0x00000004)) {
 178     // Used to have separate timers for "doit" and "all", but the timer
 179     // overhead skewed the measurements.
 180     jlong doit_time = _timer_rsc_phase1.milliseconds() +
 181                       _timer_rsc_phase2.milliseconds();
 182     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
 183 
 184     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
 185       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
 186       _timer_vm_op_prologue.milliseconds(), doit_time));
 187     RC_TRACE(0x00000004,
 188       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
 189        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
 190   }
 191 }
 192 
 193 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
 194   // classes for primitives cannot be redefined
 195   if (java_lang_Class::is_primitive(klass_mirror)) {
 196     return false;
 197   }
 198   Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
 199   // classes for arrays cannot be redefined
 200   if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
 201     return false;
 202   }
 203   return true;
 204 }
 205 
 206 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
 207 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
 208 // direct CP entries, there is just the current entry to append. For
 209 // indirect and double-indirect CP entries, there are zero or more
 210 // referenced CP entries along with the current entry to append.
 211 // Indirect and double-indirect CP entries are handled by recursive
 212 // calls to append_entry() as needed. The referenced CP entries are
 213 // always appended to *merge_cp_p before the referee CP entry. These
 214 // referenced CP entries may already exist in *merge_cp_p in which case
 215 // there is nothing extra to append and only the current entry is
 216 // appended.
 217 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
 218        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
 219        TRAPS) {
 220 
 221   // append is different depending on entry tag type
 222   switch (scratch_cp->tag_at(scratch_i).value()) {
 223 
 224     // The old verifier is implemented outside the VM. It loads classes,
 225     // but does not resolve constant pool entries directly so we never
 226     // see Class entries here with the old verifier. Similarly the old
 227     // verifier does not like Class entries in the input constant pool.
 228     // The split-verifier is implemented in the VM so it can optionally
 229     // and directly resolve constant pool entries to load classes. The
 230     // split-verifier can accept either Class entries or UnresolvedClass
 231     // entries in the input constant pool. We revert the appended copy
 232     // back to UnresolvedClass so that either verifier will be happy
 233     // with the constant pool entry.
 234     case JVM_CONSTANT_Class:
 235     {
 236       // revert the copy to JVM_CONSTANT_UnresolvedClass
 237       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
 238         scratch_cp->klass_name_at(scratch_i));
 239 
 240       if (scratch_i != *merge_cp_length_p) {
 241         // The new entry in *merge_cp_p is at a different index than
 242         // the new entry in scratch_cp so we need to map the index values.
 243         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 244       }
 245       (*merge_cp_length_p)++;
 246     } break;
 247 
 248     // these are direct CP entries so they can be directly appended,
 249     // but double and long take two constant pool entries
 250     case JVM_CONSTANT_Double:  // fall through
 251     case JVM_CONSTANT_Long:
 252     {
 253       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 254         THREAD);
 255 
 256       if (scratch_i != *merge_cp_length_p) {
 257         // The new entry in *merge_cp_p is at a different index than
 258         // the new entry in scratch_cp so we need to map the index values.
 259         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 260       }
 261       (*merge_cp_length_p) += 2;
 262     } break;
 263 
 264     // these are direct CP entries so they can be directly appended
 265     case JVM_CONSTANT_Float:   // fall through
 266     case JVM_CONSTANT_Integer: // fall through
 267     case JVM_CONSTANT_Utf8:    // fall through
 268 
 269     // This was an indirect CP entry, but it has been changed into
 270     // Symbol*s so this entry can be directly appended.
 271     case JVM_CONSTANT_String:      // fall through
 272 
 273     // These were indirect CP entries, but they have been changed into
 274     // Symbol*s so these entries can be directly appended.
 275     case JVM_CONSTANT_UnresolvedClass:  // fall through
 276     {
 277       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
 278         THREAD);
 279 
 280       if (scratch_i != *merge_cp_length_p) {
 281         // The new entry in *merge_cp_p is at a different index than
 282         // the new entry in scratch_cp so we need to map the index values.
 283         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 284       }
 285       (*merge_cp_length_p)++;
 286     } break;
 287 
 288     // this is an indirect CP entry so it needs special handling
 289     case JVM_CONSTANT_NameAndType:
 290     {
 291       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
 292       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
 293                                                          merge_cp_length_p, THREAD);
 294 
 295       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
 296       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
 297                                                               merge_cp_p, merge_cp_length_p,
 298                                                               THREAD);
 299 
 300       // If the referenced entries already exist in *merge_cp_p, then
 301       // both new_name_ref_i and new_signature_ref_i will both be 0.
 302       // In that case, all we are appending is the current entry.
 303       if (new_name_ref_i != name_ref_i) {
 304         RC_TRACE(0x00080000,
 305           ("NameAndType entry@%d name_ref_index change: %d to %d",
 306           *merge_cp_length_p, name_ref_i, new_name_ref_i));
 307       }
 308       if (new_signature_ref_i != signature_ref_i) {
 309         RC_TRACE(0x00080000,
 310           ("NameAndType entry@%d signature_ref_index change: %d to %d",
 311           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
 312       }
 313 
 314       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
 315         new_name_ref_i, new_signature_ref_i);
 316       if (scratch_i != *merge_cp_length_p) {
 317         // The new entry in *merge_cp_p is at a different index than
 318         // the new entry in scratch_cp so we need to map the index values.
 319         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 320       }
 321       (*merge_cp_length_p)++;
 322     } break;
 323 
 324     // this is a double-indirect CP entry so it needs special handling
 325     case JVM_CONSTANT_Fieldref:           // fall through
 326     case JVM_CONSTANT_InterfaceMethodref: // fall through
 327     case JVM_CONSTANT_Methodref:
 328     {
 329       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
 330       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
 331                                                           merge_cp_p, merge_cp_length_p, THREAD);
 332 
 333       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
 334       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
 335                                                           merge_cp_p, merge_cp_length_p, THREAD);
 336 
 337       const char *entry_name;
 338       switch (scratch_cp->tag_at(scratch_i).value()) {
 339       case JVM_CONSTANT_Fieldref:
 340         entry_name = "Fieldref";
 341         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
 342           new_name_and_type_ref_i);
 343         break;
 344       case JVM_CONSTANT_InterfaceMethodref:
 345         entry_name = "IFMethodref";
 346         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
 347           new_klass_ref_i, new_name_and_type_ref_i);
 348         break;
 349       case JVM_CONSTANT_Methodref:
 350         entry_name = "Methodref";
 351         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
 352           new_name_and_type_ref_i);
 353         break;
 354       default:
 355         guarantee(false, "bad switch");
 356         break;
 357       }
 358 
 359       if (klass_ref_i != new_klass_ref_i) {
 360         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
 361           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
 362       }
 363       if (name_and_type_ref_i != new_name_and_type_ref_i) {
 364         RC_TRACE(0x00080000,
 365           ("%s entry@%d name_and_type_index changed: %d to %d",
 366           entry_name, *merge_cp_length_p, name_and_type_ref_i,
 367           new_name_and_type_ref_i));
 368       }
 369 
 370       if (scratch_i != *merge_cp_length_p) {
 371         // The new entry in *merge_cp_p is at a different index than
 372         // the new entry in scratch_cp so we need to map the index values.
 373         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 374       }
 375       (*merge_cp_length_p)++;
 376     } break;
 377 
 378     // this is an indirect CP entry so it needs special handling
 379     case JVM_CONSTANT_MethodType:
 380     {
 381       int ref_i = scratch_cp->method_type_index_at(scratch_i);
 382       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 383                                                     merge_cp_length_p, THREAD);
 384       if (new_ref_i != ref_i) {
 385         RC_TRACE(0x00080000,
 386                  ("MethodType entry@%d ref_index change: %d to %d",
 387                   *merge_cp_length_p, ref_i, new_ref_i));
 388       }
 389       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
 390       if (scratch_i != *merge_cp_length_p) {
 391         // The new entry in *merge_cp_p is at a different index than
 392         // the new entry in scratch_cp so we need to map the index values.
 393         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 394       }
 395       (*merge_cp_length_p)++;
 396     } break;
 397 
 398     // this is an indirect CP entry so it needs special handling
 399     case JVM_CONSTANT_MethodHandle:
 400     {
 401       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
 402       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
 403       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
 404                                                     merge_cp_length_p, THREAD);
 405       if (new_ref_i != ref_i) {
 406         RC_TRACE(0x00080000,
 407                  ("MethodHandle entry@%d ref_index change: %d to %d",
 408                   *merge_cp_length_p, ref_i, new_ref_i));
 409       }
 410       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
 411       if (scratch_i != *merge_cp_length_p) {
 412         // The new entry in *merge_cp_p is at a different index than
 413         // the new entry in scratch_cp so we need to map the index values.
 414         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 415       }
 416       (*merge_cp_length_p)++;
 417     } break;
 418 
 419     // this is an indirect CP entry so it needs special handling
 420     case JVM_CONSTANT_InvokeDynamic:
 421     {
 422       // Index of the bootstrap specifier in the operands array
 423       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
 424       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
 425                                             merge_cp_length_p, THREAD);
 426       // The bootstrap method NameAndType_info index
 427       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
 428       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 429                                                     merge_cp_length_p, THREAD);
 430       if (new_bs_i != old_bs_i) {
 431         RC_TRACE(0x00080000,
 432                  ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
 433                   *merge_cp_length_p, old_bs_i, new_bs_i));
 434       }
 435       if (new_ref_i != old_ref_i) {
 436         RC_TRACE(0x00080000,
 437                  ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
 438                   *merge_cp_length_p, old_ref_i, new_ref_i));
 439       }
 440 
 441       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
 442       if (scratch_i != *merge_cp_length_p) {
 443         // The new entry in *merge_cp_p is at a different index than
 444         // the new entry in scratch_cp so we need to map the index values.
 445         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
 446       }
 447       (*merge_cp_length_p)++;
 448     } break;
 449 
 450     // At this stage, Class or UnresolvedClass could be here, but not
 451     // ClassIndex
 452     case JVM_CONSTANT_ClassIndex: // fall through
 453 
 454     // Invalid is used as the tag for the second constant pool entry
 455     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
 456     // not be seen by itself.
 457     case JVM_CONSTANT_Invalid: // fall through
 458 
 459     // At this stage, String could be here, but not StringIndex
 460     case JVM_CONSTANT_StringIndex: // fall through
 461 
 462     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
 463     // here
 464     case JVM_CONSTANT_UnresolvedClassInError: // fall through
 465 
 466     default:
 467     {
 468       // leave a breadcrumb
 469       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
 470       ShouldNotReachHere();
 471     } break;
 472   } // end switch tag value
 473 } // end append_entry()
 474 
 475 
 476 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
 477       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 478 
 479   int new_ref_i = ref_i;
 480   bool match = (ref_i < *merge_cp_length_p) &&
 481                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
 482 
 483   if (!match) {
 484     // forward reference in *merge_cp_p or not a direct match
 485     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
 486     if (found_i != 0) {
 487       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
 488       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
 489       new_ref_i = found_i;
 490       map_index(scratch_cp, ref_i, found_i);
 491     } else {
 492       // no match found so we have to append this entry to *merge_cp_p
 493       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
 494       // The above call to append_entry() can only append one entry
 495       // so the post call query of *merge_cp_length_p is only for
 496       // the sake of consistency.
 497       new_ref_i = *merge_cp_length_p - 1;
 498     }
 499   }
 500 
 501   return new_ref_i;
 502 } // end find_or_append_indirect_entry()
 503 
 504 
 505 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
 506 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
 507 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
 508 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
 509        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 510 
 511   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
 512   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
 513                                                 merge_cp_length_p, THREAD);
 514   if (new_ref_i != old_ref_i) {
 515     RC_TRACE(0x00080000,
 516              ("operands entry@%d bootstrap method ref_index change: %d to %d",
 517               _operands_cur_length, old_ref_i, new_ref_i));
 518   }
 519 
 520   Array<u2>* merge_ops = (*merge_cp_p)->operands();
 521   int new_bs_i = _operands_cur_length;
 522   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
 523   // However, the operand_offset_at(0) was set in the extend_operands() call.
 524   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
 525                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
 526   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
 527 
 528   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
 529   merge_ops->at_put(new_base++, new_ref_i);
 530   merge_ops->at_put(new_base++, argc);
 531 
 532   for (int i = 0; i < argc; i++) {
 533     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
 534     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
 535                                                       merge_cp_length_p, THREAD);
 536     merge_ops->at_put(new_base++, new_arg_ref_i);
 537     if (new_arg_ref_i != old_arg_ref_i) {
 538       RC_TRACE(0x00080000,
 539                ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
 540                 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));
 541     }
 542   }
 543   if (old_bs_i != _operands_cur_length) {
 544     // The bootstrap specifier in *merge_cp_p is at a different index than
 545     // that in scratch_cp so we need to map the index values.
 546     map_operand_index(old_bs_i, new_bs_i);
 547   }
 548   _operands_cur_length++;
 549 } // end append_operand()
 550 
 551 
 552 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
 553       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
 554 
 555   int new_bs_i = old_bs_i; // bootstrap specifier index
 556   bool match = (old_bs_i < _operands_cur_length) &&
 557                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
 558 
 559   if (!match) {
 560     // forward reference in *merge_cp_p or not a direct match
 561     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
 562                                                     _operands_cur_length, THREAD);
 563     if (found_i != -1) {
 564       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
 565       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
 566       new_bs_i = found_i;
 567       map_operand_index(old_bs_i, found_i);
 568     } else {
 569       // no match found so we have to append this bootstrap specifier to *merge_cp_p
 570       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
 571       new_bs_i = _operands_cur_length - 1;
 572     }
 573   }
 574   return new_bs_i;
 575 } // end find_or_append_operand()
 576 
 577 
 578 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
 579   if (merge_cp->operands() == NULL) {
 580     return;
 581   }
 582   // Shrink the merge_cp operands
 583   merge_cp->shrink_operands(_operands_cur_length, CHECK);
 584 
 585   if (RC_TRACE_ENABLED(0x00040000)) {
 586     // don't want to loop unless we are tracing
 587     int count = 0;
 588     for (int i = 1; i < _operands_index_map_p->length(); i++) {
 589       int value = _operands_index_map_p->at(i);
 590       if (value != -1) {
 591         RC_TRACE_WITH_THREAD(0x00040000, THREAD,
 592           ("operands_index_map[%d]: old=%d new=%d", count, i, value));
 593         count++;
 594       }
 595     }
 596   }
 597   // Clean-up
 598   _operands_index_map_p = NULL;
 599   _operands_cur_length = 0;
 600   _operands_index_map_count = 0;
 601 } // end finalize_operands_merge()
 602 
 603 
 604 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
 605              instanceKlassHandle the_class,
 606              instanceKlassHandle scratch_class) {
 607   int i;
 608 
 609   // Check superclasses, or rather their names, since superclasses themselves can be
 610   // requested to replace.
 611   // Check for NULL superclass first since this might be java.lang.Object
 612   if (the_class->super() != scratch_class->super() &&
 613       (the_class->super() == NULL || scratch_class->super() == NULL ||
 614        the_class->super()->name()->not_equals(
 615        scratch_class->super()->name()))) {
 616     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 617   }
 618 
 619   // Check if the number, names and order of directly implemented interfaces are the same.
 620   // I think in principle we should just check if the sets of names of directly implemented
 621   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
 622   // .java file, also changes in .class file) should not matter. However, comparing sets is
 623   // technically a bit more difficult, and, more importantly, I am not sure at present that the
 624   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
 625   // rely on it somewhere.
 626   Array<Klass*>* k_interfaces = the_class->local_interfaces();
 627   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
 628   int n_intfs = k_interfaces->length();
 629   if (n_intfs != k_new_interfaces->length()) {
 630     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 631   }
 632   for (i = 0; i < n_intfs; i++) {
 633     if (k_interfaces->at(i)->name()->not_equals(
 634         k_new_interfaces->at(i)->name())) {
 635       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
 636     }
 637   }
 638 
 639   // Check whether class is in the error init state.
 640   if (the_class->is_in_error_state()) {
 641     // TBD #5057930: special error code is needed in 1.6
 642     return JVMTI_ERROR_INVALID_CLASS;
 643   }
 644 
 645   // Check whether class modifiers are the same.
 646   jushort old_flags = (jushort) the_class->access_flags().get_flags();
 647   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
 648   if (old_flags != new_flags) {
 649     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
 650   }
 651 
 652   // Check if the number, names, types and order of fields declared in these classes
 653   // are the same.
 654   JavaFieldStream old_fs(the_class);
 655   JavaFieldStream new_fs(scratch_class);
 656   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
 657     // access
 658     old_flags = old_fs.access_flags().as_short();
 659     new_flags = new_fs.access_flags().as_short();
 660     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
 661       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 662     }
 663     // offset
 664     if (old_fs.offset() != new_fs.offset()) {
 665       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 666     }
 667     // name and signature
 668     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
 669     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
 670     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
 671     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
 672     if (name_sym1->not_equals(name_sym2) || sig_sym1->not_equals(sig_sym2)) {
 673       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 674     }
 675   }
 676 
 677   // If both streams aren't done then we have a differing number of
 678   // fields.
 679   if (!old_fs.done() || !new_fs.done()) {
 680     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
 681   }
 682 
 683   // Do a parallel walk through the old and new methods. Detect
 684   // cases where they match (exist in both), have been added in
 685   // the new methods, or have been deleted (exist only in the
 686   // old methods).  The class file parser places methods in order
 687   // by method name, but does not order overloaded methods by
 688   // signature.  In order to determine what fate befell the methods,
 689   // this code places the overloaded new methods that have matching
 690   // old methods in the same order as the old methods and places
 691   // new overloaded methods at the end of overloaded methods of
 692   // that name. The code for this order normalization is adapted
 693   // from the algorithm used in InstanceKlass::find_method().
 694   // Since we are swapping out of order entries as we find them,
 695   // we only have to search forward through the overloaded methods.
 696   // Methods which are added and have the same name as an existing
 697   // method (but different signature) will be put at the end of
 698   // the methods with that name, and the name mismatch code will
 699   // handle them.
 700   Array<Method*>* k_old_methods(the_class->methods());
 701   Array<Method*>* k_new_methods(scratch_class->methods());
 702   int n_old_methods = k_old_methods->length();
 703   int n_new_methods = k_new_methods->length();
 704   Thread* thread = Thread::current();
 705 
 706   int ni = 0;
 707   int oi = 0;
 708   while (true) {
 709     Method* k_old_method;
 710     Method* k_new_method;
 711     enum { matched, added, deleted, undetermined } method_was = undetermined;
 712 
 713     if (oi >= n_old_methods) {
 714       if (ni >= n_new_methods) {
 715         break; // we've looked at everything, done
 716       }
 717       // New method at the end
 718       k_new_method = k_new_methods->at(ni);
 719       method_was = added;
 720     } else if (ni >= n_new_methods) {
 721       // Old method, at the end, is deleted
 722       k_old_method = k_old_methods->at(oi);
 723       method_was = deleted;
 724     } else {
 725       // There are more methods in both the old and new lists
 726       k_old_method = k_old_methods->at(oi);
 727       k_new_method = k_new_methods->at(ni);
 728       if (k_old_method->name()->not_equals(k_new_method->name())) {
 729         // Methods are sorted by method name, so a mismatch means added
 730         // or deleted
 731         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
 732           method_was = added;
 733         } else {
 734           method_was = deleted;
 735         }
 736       } else if (k_old_method->signature()->equals(k_new_method->signature())) {
 737         // Both the name and signature match
 738         method_was = matched;
 739       } else {
 740         // The name matches, but the signature doesn't, which means we have to
 741         // search forward through the new overloaded methods.
 742         int nj;  // outside the loop for post-loop check
 743         for (nj = ni + 1; nj < n_new_methods; nj++) {
 744           Method* m = k_new_methods->at(nj);
 745           if (k_old_method->name()->not_equals(m->name())) {
 746             // reached another method name so no more overloaded methods
 747             method_was = deleted;
 748             break;
 749           }
 750           if (k_old_method->signature()->equals(m->signature())) {
 751             // found a match so swap the methods
 752             k_new_methods->at_put(ni, m);
 753             k_new_methods->at_put(nj, k_new_method);
 754             k_new_method = m;
 755             method_was = matched;
 756             break;
 757           }
 758         }
 759 
 760         if (nj >= n_new_methods) {
 761           // reached the end without a match; so method was deleted
 762           method_was = deleted;
 763         }
 764       }
 765     }
 766 
 767     switch (method_was) {
 768     case matched:
 769       // methods match, be sure modifiers do too
 770       old_flags = (jushort) k_old_method->access_flags().get_flags();
 771       new_flags = (jushort) k_new_method->access_flags().get_flags();
 772       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
 773         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
 774       }
 775       {
 776         u2 new_num = k_new_method->method_idnum();
 777         u2 old_num = k_old_method->method_idnum();
 778         if (new_num != old_num) {
 779           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
 780           if (idnum_owner != NULL) {
 781             // There is already a method assigned this idnum -- switch them
 782             // Take current and original idnum from the new_method
 783             idnum_owner->set_method_idnum(new_num);
 784             idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 785           }
 786           // Take current and original idnum from the old_method
 787           k_new_method->set_method_idnum(old_num);
 788           k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
 789           if (thread->has_pending_exception()) {
 790             return JVMTI_ERROR_OUT_OF_MEMORY;
 791           }
 792         }
 793       }
 794       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
 795                             k_new_method->name_and_sig_as_C_string(), ni,
 796                             k_old_method->name_and_sig_as_C_string(), oi));
 797       // advance to next pair of methods
 798       ++oi;
 799       ++ni;
 800       break;
 801     case added:
 802       // method added, see if it is OK
 803       new_flags = (jushort) k_new_method->access_flags().get_flags();
 804       if ((new_flags & JVM_ACC_PRIVATE) == 0
 805            // hack: private should be treated as final, but alas
 806           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 807          ) {
 808         // new methods must be private
 809         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 810       }
 811       {
 812         u2 num = the_class->next_method_idnum();
 813         if (num == ConstMethod::UNSET_IDNUM) {
 814           // cannot add any more methods
 815           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
 816         }
 817         u2 new_num = k_new_method->method_idnum();
 818         Method* idnum_owner = scratch_class->method_with_idnum(num);
 819         if (idnum_owner != NULL) {
 820           // There is already a method assigned this idnum -- switch them
 821           // Take current and original idnum from the new_method
 822           idnum_owner->set_method_idnum(new_num);
 823           idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
 824         }
 825         k_new_method->set_method_idnum(num);
 826         k_new_method->set_orig_method_idnum(num);
 827         if (thread->has_pending_exception()) {
 828           return JVMTI_ERROR_OUT_OF_MEMORY;
 829         }
 830       }
 831       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
 832                             k_new_method->name_and_sig_as_C_string(), ni));
 833       ++ni; // advance to next new method
 834       break;
 835     case deleted:
 836       // method deleted, see if it is OK
 837       old_flags = (jushort) k_old_method->access_flags().get_flags();
 838       if ((old_flags & JVM_ACC_PRIVATE) == 0
 839            // hack: private should be treated as final, but alas
 840           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
 841          ) {
 842         // deleted methods must be private
 843         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
 844       }
 845       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
 846                             k_old_method->name_and_sig_as_C_string(), oi));
 847       ++oi; // advance to next old method
 848       break;
 849     default:
 850       ShouldNotReachHere();
 851     }
 852   }
 853 
 854   return JVMTI_ERROR_NONE;
 855 }
 856 
 857 
 858 // Find new constant pool index value for old constant pool index value
 859 // by seaching the index map. Returns zero (0) if there is no mapped
 860 // value for the old constant pool index.
 861 int VM_RedefineClasses::find_new_index(int old_index) {
 862   if (_index_map_count == 0) {
 863     // map is empty so nothing can be found
 864     return 0;
 865   }
 866 
 867   if (old_index < 1 || old_index >= _index_map_p->length()) {
 868     // The old_index is out of range so it is not mapped. This should
 869     // not happen in regular constant pool merging use, but it can
 870     // happen if a corrupt annotation is processed.
 871     return 0;
 872   }
 873 
 874   int value = _index_map_p->at(old_index);
 875   if (value == -1) {
 876     // the old_index is not mapped
 877     return 0;
 878   }
 879 
 880   return value;
 881 } // end find_new_index()
 882 
 883 
 884 // Find new bootstrap specifier index value for old bootstrap specifier index
 885 // value by seaching the index map. Returns unused index (-1) if there is
 886 // no mapped value for the old bootstrap specifier index.
 887 int VM_RedefineClasses::find_new_operand_index(int old_index) {
 888   if (_operands_index_map_count == 0) {
 889     // map is empty so nothing can be found
 890     return -1;
 891   }
 892 
 893   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
 894     // The old_index is out of range so it is not mapped.
 895     // This should not happen in regular constant pool merging use.
 896     return -1;
 897   }
 898 
 899   int value = _operands_index_map_p->at(old_index);
 900   if (value == -1) {
 901     // the old_index is not mapped
 902     return -1;
 903   }
 904 
 905   return value;
 906 } // end find_new_operand_index()
 907 
 908 
 909 // Returns true if the current mismatch is due to a resolved/unresolved
 910 // class pair. Otherwise, returns false.
 911 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
 912        int index1, constantPoolHandle cp2, int index2) {
 913 
 914   jbyte t1 = cp1->tag_at(index1).value();
 915   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
 916     return false;  // wrong entry type; not our special case
 917   }
 918 
 919   jbyte t2 = cp2->tag_at(index2).value();
 920   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
 921     return false;  // wrong entry type; not our special case
 922   }
 923 
 924   if (t1 == t2) {
 925     return false;  // not a mismatch; not our special case
 926   }
 927 
 928   char *s1 = cp1->klass_name_at(index1)->as_C_string();
 929   char *s2 = cp2->klass_name_at(index2)->as_C_string();
 930   if (strcmp(s1, s2) != 0) {
 931     return false;  // strings don't match; not our special case
 932   }
 933 
 934   return true;  // made it through the gauntlet; this is our special case
 935 } // end is_unresolved_class_mismatch()
 936 
 937 
 938 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
 939 
 940   // For consistency allocate memory using os::malloc wrapper.
 941   _scratch_classes = (Klass**)
 942     os::malloc(sizeof(Klass*) * _class_count, mtClass);
 943   if (_scratch_classes == NULL) {
 944     return JVMTI_ERROR_OUT_OF_MEMORY;
 945   }
 946   // Zero initialize the _scratch_classes array.
 947   for (int i = 0; i < _class_count; i++) {
 948     _scratch_classes[i] = NULL;
 949   }
 950 
 951   ResourceMark rm(THREAD);
 952 
 953   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
 954   // state can only be NULL if the current thread is exiting which
 955   // should not happen since we're trying to do a RedefineClasses
 956   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
 957   for (int i = 0; i < _class_count; i++) {
 958     // Create HandleMark so that any handles created while loading new class
 959     // versions are deleted. Constant pools are deallocated while merging
 960     // constant pools
 961     HandleMark hm(THREAD);
 962 
 963     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
 964     // classes for primitives cannot be redefined
 965     if (!is_modifiable_class(mirror)) {
 966       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
 967     }
 968     Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
 969     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
 970     Symbol*  the_class_sym = the_class->name();
 971 
 972     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
 973     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
 974       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
 975       the_class->external_name(), _class_load_kind,
 976       os::available_memory() >> 10));
 977 
 978     ClassFileStream st((u1*) _class_defs[i].class_bytes,
 979       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
 980 
 981     // Parse the stream.
 982     Handle the_class_loader(THREAD, the_class->class_loader());
 983     Handle protection_domain(THREAD, the_class->protection_domain());
 984     // Set redefined class handle in JvmtiThreadState class.
 985     // This redefined class is sent to agent event handler for class file
 986     // load hook event.
 987     state->set_class_being_redefined(&the_class, _class_load_kind);
 988 
 989     Klass* k = SystemDictionary::parse_stream(the_class_sym,
 990                                                 the_class_loader,
 991                                                 protection_domain,
 992                                                 &st,
 993                                                 THREAD);
 994     // Clear class_being_redefined just to be sure.
 995     state->clear_class_being_redefined();
 996 
 997     // TODO: if this is retransform, and nothing changed we can skip it
 998 
 999     instanceKlassHandle scratch_class (THREAD, k);
1000 
1001     // Need to clean up allocated InstanceKlass if there's an error so assign
1002     // the result here. Caller deallocates all the scratch classes in case of
1003     // an error.
1004     _scratch_classes[i] = k;
1005 
1006     if (HAS_PENDING_EXCEPTION) {
1007       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1008       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1009       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
1010         ex_name->as_C_string()));
1011       CLEAR_PENDING_EXCEPTION;
1012 
1013       if (ex_name->equals(vmSymbols::java_lang_UnsupportedClassVersionError())) {
1014         return JVMTI_ERROR_UNSUPPORTED_VERSION;
1015       } else if (ex_name->equals(vmSymbols::java_lang_ClassFormatError())) {
1016         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1017       } else if (ex_name->equals(vmSymbols::java_lang_ClassCircularityError())) {
1018         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1019       } else if (ex_name->equals(vmSymbols::java_lang_NoClassDefFoundError())) {
1020         // The message will be "XXX (wrong name: YYY)"
1021         return JVMTI_ERROR_NAMES_DONT_MATCH;
1022       } else if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1023         return JVMTI_ERROR_OUT_OF_MEMORY;
1024       } else {  // Just in case more exceptions can be thrown..
1025         return JVMTI_ERROR_FAILS_VERIFICATION;
1026       }
1027     }
1028 
1029     // Ensure class is linked before redefine
1030     if (!the_class->is_linked()) {
1031       the_class->link_class(THREAD);
1032       if (HAS_PENDING_EXCEPTION) {
1033         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1034         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1035         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
1036           ex_name->as_C_string()));
1037         CLEAR_PENDING_EXCEPTION;
1038         if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1039           return JVMTI_ERROR_OUT_OF_MEMORY;
1040         } else {
1041           return JVMTI_ERROR_INTERNAL;
1042         }
1043       }
1044     }
1045 
1046     // Do the validity checks in compare_and_normalize_class_versions()
1047     // before verifying the byte codes. By doing these checks first, we
1048     // limit the number of functions that require redirection from
1049     // the_class to scratch_class. In particular, we don't have to
1050     // modify JNI GetSuperclass() and thus won't change its performance.
1051     jvmtiError res = compare_and_normalize_class_versions(the_class,
1052                        scratch_class);
1053     if (res != JVMTI_ERROR_NONE) {
1054       return res;
1055     }
1056 
1057     // verify what the caller passed us
1058     {
1059       // The bug 6214132 caused the verification to fail.
1060       // Information about the_class and scratch_class is temporarily
1061       // recorded into jvmtiThreadState. This data is used to redirect
1062       // the_class to scratch_class in the JVM_* functions called by the
1063       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1064       // description.
1065       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1066       Verifier::verify(
1067         scratch_class, Verifier::ThrowException, true, THREAD);
1068     }
1069 
1070     if (HAS_PENDING_EXCEPTION) {
1071       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1072       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1073       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1074         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
1075       CLEAR_PENDING_EXCEPTION;
1076       if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1077         return JVMTI_ERROR_OUT_OF_MEMORY;
1078       } else {
1079         // tell the caller the bytecodes are bad
1080         return JVMTI_ERROR_FAILS_VERIFICATION;
1081       }
1082     }
1083 
1084     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1085     if (HAS_PENDING_EXCEPTION) {
1086       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1087       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1088       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1089         ("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()));
1090       CLEAR_PENDING_EXCEPTION;
1091       if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1092         return JVMTI_ERROR_OUT_OF_MEMORY;
1093       } else {
1094         return JVMTI_ERROR_INTERNAL;
1095       }
1096     }
1097 
1098     if (VerifyMergedCPBytecodes) {
1099       // verify what we have done during constant pool merging
1100       {
1101         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1102         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1103       }
1104 
1105       if (HAS_PENDING_EXCEPTION) {
1106         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1107         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1108         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1109           ("verify_byte_codes post merge-CP exception: '%s'",
1110           ex_name->as_C_string()));
1111         CLEAR_PENDING_EXCEPTION;
1112         if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1113           return JVMTI_ERROR_OUT_OF_MEMORY;
1114         } else {
1115           // tell the caller that constant pool merging screwed up
1116           return JVMTI_ERROR_INTERNAL;
1117         }
1118       }
1119     }
1120 
1121     Rewriter::rewrite(scratch_class, THREAD);
1122     if (!HAS_PENDING_EXCEPTION) {
1123       scratch_class->link_methods(THREAD);
1124     }
1125     if (HAS_PENDING_EXCEPTION) {
1126       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1127       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1128       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1129         ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()));
1130       CLEAR_PENDING_EXCEPTION;
1131       if (ex_name->equals(vmSymbols::java_lang_OutOfMemoryError())) {
1132         return JVMTI_ERROR_OUT_OF_MEMORY;
1133       } else {
1134         return JVMTI_ERROR_INTERNAL;
1135       }
1136     }
1137 
1138     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1139     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1140       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1141       the_class->external_name(), os::available_memory() >> 10));
1142   }
1143 
1144   return JVMTI_ERROR_NONE;
1145 }
1146 
1147 
1148 // Map old_index to new_index as needed. scratch_cp is only needed
1149 // for RC_TRACE() calls.
1150 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1151        int old_index, int new_index) {
1152   if (find_new_index(old_index) != 0) {
1153     // old_index is already mapped
1154     return;
1155   }
1156 
1157   if (old_index == new_index) {
1158     // no mapping is needed
1159     return;
1160   }
1161 
1162   _index_map_p->at_put(old_index, new_index);
1163   _index_map_count++;
1164 
1165   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1166     scratch_cp->tag_at(old_index).value(), old_index, new_index));
1167 } // end map_index()
1168 
1169 
1170 // Map old_index to new_index as needed.
1171 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1172   if (find_new_operand_index(old_index) != -1) {
1173     // old_index is already mapped
1174     return;
1175   }
1176 
1177   if (old_index == new_index) {
1178     // no mapping is needed
1179     return;
1180   }
1181 
1182   _operands_index_map_p->at_put(old_index, new_index);
1183   _operands_index_map_count++;
1184 
1185   RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
1186 } // end map_index()
1187 
1188 
1189 // Merge old_cp and scratch_cp and return the results of the merge via
1190 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1191 // merge_cp_length_p. The entries in old_cp occupy the same locations
1192 // in *merge_cp_p. Also creates a map of indices from entries in
1193 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1194 // entries are only created for entries in scratch_cp that occupy a
1195 // different location in *merged_cp_p.
1196 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1197        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1198        int *merge_cp_length_p, TRAPS) {
1199 
1200   if (merge_cp_p == NULL) {
1201     assert(false, "caller must provide scratch constantPool");
1202     return false; // robustness
1203   }
1204   if (merge_cp_length_p == NULL) {
1205     assert(false, "caller must provide scratch CP length");
1206     return false; // robustness
1207   }
1208   // Worst case we need old_cp->length() + scratch_cp()->length(),
1209   // but the caller might be smart so make sure we have at least
1210   // the minimum.
1211   if ((*merge_cp_p)->length() < old_cp->length()) {
1212     assert(false, "merge area too small");
1213     return false; // robustness
1214   }
1215 
1216   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1217     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1218     scratch_cp->length()));
1219 
1220   {
1221     // Pass 0:
1222     // The old_cp is copied to *merge_cp_p; this means that any code
1223     // using old_cp does not have to change. This work looks like a
1224     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1225     // handle one special case:
1226     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1227     // This will make verification happy.
1228 
1229     int old_i;  // index into old_cp
1230 
1231     // index zero (0) is not used in constantPools
1232     for (old_i = 1; old_i < old_cp->length(); old_i++) {
1233       // leave debugging crumb
1234       jbyte old_tag = old_cp->tag_at(old_i).value();
1235       switch (old_tag) {
1236       case JVM_CONSTANT_Class:
1237       case JVM_CONSTANT_UnresolvedClass:
1238         // revert the copy to JVM_CONSTANT_UnresolvedClass
1239         // May be resolving while calling this so do the same for
1240         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1241         (*merge_cp_p)->unresolved_klass_at_put(old_i,
1242           old_cp->klass_name_at(old_i));
1243         break;
1244 
1245       case JVM_CONSTANT_Double:
1246       case JVM_CONSTANT_Long:
1247         // just copy the entry to *merge_cp_p, but double and long take
1248         // two constant pool entries
1249         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1250         old_i++;
1251         break;
1252 
1253       default:
1254         // just copy the entry to *merge_cp_p
1255         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1256         break;
1257       }
1258     } // end for each old_cp entry
1259 
1260     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1261     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1262 
1263     // We don't need to sanity check that *merge_cp_length_p is within
1264     // *merge_cp_p bounds since we have the minimum on-entry check above.
1265     (*merge_cp_length_p) = old_i;
1266   }
1267 
1268   // merge_cp_len should be the same as old_cp->length() at this point
1269   // so this trace message is really a "warm-and-breathing" message.
1270   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1271     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1272 
1273   int scratch_i;  // index into scratch_cp
1274   {
1275     // Pass 1a:
1276     // Compare scratch_cp entries to the old_cp entries that we have
1277     // already copied to *merge_cp_p. In this pass, we are eliminating
1278     // exact duplicates (matching entry at same index) so we only
1279     // compare entries in the common indice range.
1280     int increment = 1;
1281     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1282     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1283       switch (scratch_cp->tag_at(scratch_i).value()) {
1284       case JVM_CONSTANT_Double:
1285       case JVM_CONSTANT_Long:
1286         // double and long take two constant pool entries
1287         increment = 2;
1288         break;
1289 
1290       default:
1291         increment = 1;
1292         break;
1293       }
1294 
1295       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1296         scratch_i, CHECK_0);
1297       if (match) {
1298         // found a match at the same index so nothing more to do
1299         continue;
1300       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1301                                               *merge_cp_p, scratch_i)) {
1302         // The mismatch in compare_entry_to() above is because of a
1303         // resolved versus unresolved class entry at the same index
1304         // with the same string value. Since Pass 0 reverted any
1305         // class entries to unresolved class entries in *merge_cp_p,
1306         // we go with the unresolved class entry.
1307         continue;
1308       }
1309 
1310       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1311         CHECK_0);
1312       if (found_i != 0) {
1313         guarantee(found_i != scratch_i,
1314           "compare_entry_to() and find_matching_entry() do not agree");
1315 
1316         // Found a matching entry somewhere else in *merge_cp_p so
1317         // just need a mapping entry.
1318         map_index(scratch_cp, scratch_i, found_i);
1319         continue;
1320       }
1321 
1322       // The find_matching_entry() call above could fail to find a match
1323       // due to a resolved versus unresolved class or string entry situation
1324       // like we solved above with the is_unresolved_*_mismatch() calls.
1325       // However, we would have to call is_unresolved_*_mismatch() over
1326       // all of *merge_cp_p (potentially) and that doesn't seem to be
1327       // worth the time.
1328 
1329       // No match found so we have to append this entry and any unique
1330       // referenced entries to *merge_cp_p.
1331       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1332         CHECK_0);
1333     }
1334   }
1335 
1336   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1337     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1338     *merge_cp_length_p, scratch_i, _index_map_count));
1339 
1340   if (scratch_i < scratch_cp->length()) {
1341     // Pass 1b:
1342     // old_cp is smaller than scratch_cp so there are entries in
1343     // scratch_cp that we have not yet processed. We take care of
1344     // those now.
1345     int increment = 1;
1346     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1347       switch (scratch_cp->tag_at(scratch_i).value()) {
1348       case JVM_CONSTANT_Double:
1349       case JVM_CONSTANT_Long:
1350         // double and long take two constant pool entries
1351         increment = 2;
1352         break;
1353 
1354       default:
1355         increment = 1;
1356         break;
1357       }
1358 
1359       int found_i =
1360         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1361       if (found_i != 0) {
1362         // Found a matching entry somewhere else in *merge_cp_p so
1363         // just need a mapping entry.
1364         map_index(scratch_cp, scratch_i, found_i);
1365         continue;
1366       }
1367 
1368       // No match found so we have to append this entry and any unique
1369       // referenced entries to *merge_cp_p.
1370       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1371         CHECK_0);
1372     }
1373 
1374     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1375       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1376       *merge_cp_length_p, scratch_i, _index_map_count));
1377   }
1378   finalize_operands_merge(*merge_cp_p, THREAD);
1379 
1380   return true;
1381 } // end merge_constant_pools()
1382 
1383 
1384 // Scoped object to clean up the constant pool(s) created for merging
1385 class MergeCPCleaner {
1386   ClassLoaderData*   _loader_data;
1387   ConstantPool*      _cp;
1388   ConstantPool*      _scratch_cp;
1389  public:
1390   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1391                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1392   ~MergeCPCleaner() {
1393     _loader_data->add_to_deallocate_list(_cp);
1394     if (_scratch_cp != NULL) {
1395       _loader_data->add_to_deallocate_list(_scratch_cp);
1396     }
1397   }
1398   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1399 };
1400 
1401 // Merge constant pools between the_class and scratch_class and
1402 // potentially rewrite bytecodes in scratch_class to use the merged
1403 // constant pool.
1404 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1405              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1406              TRAPS) {
1407   // worst case merged constant pool length is old and new combined
1408   int merge_cp_length = the_class->constants()->length()
1409         + scratch_class->constants()->length();
1410 
1411   // Constant pools are not easily reused so we allocate a new one
1412   // each time.
1413   // merge_cp is created unsafe for concurrent GC processing.  It
1414   // should be marked safe before discarding it. Even though
1415   // garbage,  if it crosses a card boundary, it may be scanned
1416   // in order to find the start of the first complete object on the card.
1417   ClassLoaderData* loader_data = the_class->class_loader_data();
1418   ConstantPool* merge_cp_oop =
1419     ConstantPool::allocate(loader_data,
1420                            merge_cp_length,
1421                            CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1422   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1423 
1424   HandleMark hm(THREAD);  // make sure handles are cleared before
1425                           // MergeCPCleaner clears out merge_cp_oop
1426   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1427 
1428   // Get constants() from the old class because it could have been rewritten
1429   // while we were at a safepoint allocating a new constant pool.
1430   constantPoolHandle old_cp(THREAD, the_class->constants());
1431   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1432 
1433   // If the length changed, the class was redefined out from under us. Return
1434   // an error.
1435   if (merge_cp_length != the_class->constants()->length()
1436          + scratch_class->constants()->length()) {
1437     return JVMTI_ERROR_INTERNAL;
1438   }
1439 
1440   // Update the version number of the constant pool
1441   merge_cp->increment_and_save_version(old_cp->version());
1442 
1443   ResourceMark rm(THREAD);
1444   _index_map_count = 0;
1445   _index_map_p = new intArray(scratch_cp->length(), -1);
1446 
1447   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1448   _operands_index_map_count = 0;
1449   _operands_index_map_p = new intArray(
1450     ConstantPool::operand_array_length(scratch_cp->operands()), -1);
1451 
1452   // reference to the cp holder is needed for copy_operands()
1453   merge_cp->set_pool_holder(scratch_class());
1454   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1455                   &merge_cp_length, THREAD);
1456   merge_cp->set_pool_holder(NULL);
1457 
1458   if (!result) {
1459     // The merge can fail due to memory allocation failure or due
1460     // to robustness checks.
1461     return JVMTI_ERROR_INTERNAL;
1462   }
1463 
1464   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1465     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1466 
1467   if (_index_map_count == 0) {
1468     // there is nothing to map between the new and merged constant pools
1469 
1470     if (old_cp->length() == scratch_cp->length()) {
1471       // The old and new constant pools are the same length and the
1472       // index map is empty. This means that the three constant pools
1473       // are equivalent (but not the same). Unfortunately, the new
1474       // constant pool has not gone through link resolution nor have
1475       // the new class bytecodes gone through constant pool cache
1476       // rewriting so we can't use the old constant pool with the new
1477       // class.
1478 
1479       // toss the merged constant pool at return
1480     } else if (old_cp->length() < scratch_cp->length()) {
1481       // The old constant pool has fewer entries than the new constant
1482       // pool and the index map is empty. This means the new constant
1483       // pool is a superset of the old constant pool. However, the old
1484       // class bytecodes have already gone through constant pool cache
1485       // rewriting so we can't use the new constant pool with the old
1486       // class.
1487 
1488       // toss the merged constant pool at return
1489     } else {
1490       // The old constant pool has more entries than the new constant
1491       // pool and the index map is empty. This means that both the old
1492       // and merged constant pools are supersets of the new constant
1493       // pool.
1494 
1495       // Replace the new constant pool with a shrunken copy of the
1496       // merged constant pool
1497       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1498                             CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1499       // The new constant pool replaces scratch_cp so have cleaner clean it up.
1500       // It can't be cleaned up while there are handles to it.
1501       cp_cleaner.add_scratch_cp(scratch_cp());
1502     }
1503   } else {
1504     if (RC_TRACE_ENABLED(0x00040000)) {
1505       // don't want to loop unless we are tracing
1506       int count = 0;
1507       for (int i = 1; i < _index_map_p->length(); i++) {
1508         int value = _index_map_p->at(i);
1509 
1510         if (value != -1) {
1511           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1512             ("index_map[%d]: old=%d new=%d", count, i, value));
1513           count++;
1514         }
1515       }
1516     }
1517 
1518     // We have entries mapped between the new and merged constant pools
1519     // so we have to rewrite some constant pool references.
1520     if (!rewrite_cp_refs(scratch_class, THREAD)) {
1521       return JVMTI_ERROR_INTERNAL;
1522     }
1523 
1524     // Replace the new constant pool with a shrunken copy of the
1525     // merged constant pool so now the rewritten bytecodes have
1526     // valid references; the previous new constant pool will get
1527     // GCed.
1528     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1529                           CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1530     // The new constant pool replaces scratch_cp so have cleaner clean it up.
1531     // It can't be cleaned up while there are handles to it.
1532     cp_cleaner.add_scratch_cp(scratch_cp());
1533   }
1534 
1535   return JVMTI_ERROR_NONE;
1536 } // end merge_cp_and_rewrite()
1537 
1538 
1539 // Rewrite constant pool references in klass scratch_class.
1540 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1541        TRAPS) {
1542 
1543   // rewrite constant pool references in the methods:
1544   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1545     // propagate failure back to caller
1546     return false;
1547   }
1548 
1549   // rewrite constant pool references in the class_annotations:
1550   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1551     // propagate failure back to caller
1552     return false;
1553   }
1554 
1555   // rewrite constant pool references in the fields_annotations:
1556   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1557     // propagate failure back to caller
1558     return false;
1559   }
1560 
1561   // rewrite constant pool references in the methods_annotations:
1562   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1563     // propagate failure back to caller
1564     return false;
1565   }
1566 
1567   // rewrite constant pool references in the methods_parameter_annotations:
1568   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1569          THREAD)) {
1570     // propagate failure back to caller
1571     return false;
1572   }
1573 
1574   // rewrite constant pool references in the methods_default_annotations:
1575   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1576          THREAD)) {
1577     // propagate failure back to caller
1578     return false;
1579   }
1580 
1581   // rewrite constant pool references in the class_type_annotations:
1582   if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1583     // propagate failure back to caller
1584     return false;
1585   }
1586 
1587   // rewrite constant pool references in the fields_type_annotations:
1588   if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1589     // propagate failure back to caller
1590     return false;
1591   }
1592 
1593   // rewrite constant pool references in the methods_type_annotations:
1594   if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1595     // propagate failure back to caller
1596     return false;
1597   }
1598 
1599   // There can be type annotations in the Code part of a method_info attribute.
1600   // These annotations are not accessible, even by reflection.
1601   // Currently they are not even parsed by the ClassFileParser.
1602   // If runtime access is added they will also need to be rewritten.
1603 
1604   // rewrite source file name index:
1605   u2 source_file_name_idx = scratch_class->source_file_name_index();
1606   if (source_file_name_idx != 0) {
1607     u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1608     if (new_source_file_name_idx != 0) {
1609       scratch_class->set_source_file_name_index(new_source_file_name_idx);
1610     }
1611   }
1612 
1613   // rewrite class generic signature index:
1614   u2 generic_signature_index = scratch_class->generic_signature_index();
1615   if (generic_signature_index != 0) {
1616     u2 new_generic_signature_index = find_new_index(generic_signature_index);
1617     if (new_generic_signature_index != 0) {
1618       scratch_class->set_generic_signature_index(new_generic_signature_index);
1619     }
1620   }
1621 
1622   return true;
1623 } // end rewrite_cp_refs()
1624 
1625 // Rewrite constant pool references in the methods.
1626 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1627        instanceKlassHandle scratch_class, TRAPS) {
1628 
1629   Array<Method*>* methods = scratch_class->methods();
1630 
1631   if (methods == NULL || methods->length() == 0) {
1632     // no methods so nothing to do
1633     return true;
1634   }
1635 
1636   // rewrite constant pool references in the methods:
1637   for (int i = methods->length() - 1; i >= 0; i--) {
1638     methodHandle method(THREAD, methods->at(i));
1639     methodHandle new_method;
1640     rewrite_cp_refs_in_method(method, &new_method, THREAD);
1641     if (!new_method.is_null()) {
1642       // the method has been replaced so save the new method version
1643       // even in the case of an exception.  original method is on the
1644       // deallocation list.
1645       methods->at_put(i, new_method());
1646     }
1647     if (HAS_PENDING_EXCEPTION) {
1648       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1649       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1650       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1651         ("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()));
1652       // Need to clear pending exception here as the super caller sets
1653       // the JVMTI_ERROR_INTERNAL if the returned value is false.
1654       CLEAR_PENDING_EXCEPTION;
1655       return false;
1656     }
1657   }
1658 
1659   return true;
1660 }
1661 
1662 
1663 // Rewrite constant pool references in the specific method. This code
1664 // was adapted from Rewriter::rewrite_method().
1665 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1666        methodHandle *new_method_p, TRAPS) {
1667 
1668   *new_method_p = methodHandle();  // default is no new method
1669 
1670   // We cache a pointer to the bytecodes here in code_base. If GC
1671   // moves the Method*, then the bytecodes will also move which
1672   // will likely cause a crash. We create a No_Safepoint_Verifier
1673   // object to detect whether we pass a possible safepoint in this
1674   // code block.
1675   No_Safepoint_Verifier nsv;
1676 
1677   // Bytecodes and their length
1678   address code_base = method->code_base();
1679   int code_length = method->code_size();
1680 
1681   int bc_length;
1682   for (int bci = 0; bci < code_length; bci += bc_length) {
1683     address bcp = code_base + bci;
1684     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1685 
1686     bc_length = Bytecodes::length_for(c);
1687     if (bc_length == 0) {
1688       // More complicated bytecodes report a length of zero so
1689       // we have to try again a slightly different way.
1690       bc_length = Bytecodes::length_at(method(), bcp);
1691     }
1692 
1693     assert(bc_length != 0, "impossible bytecode length");
1694 
1695     switch (c) {
1696       case Bytecodes::_ldc:
1697       {
1698         int cp_index = *(bcp + 1);
1699         int new_index = find_new_index(cp_index);
1700 
1701         if (StressLdcRewrite && new_index == 0) {
1702           // If we are stressing ldc -> ldc_w rewriting, then we
1703           // always need a new_index value.
1704           new_index = cp_index;
1705         }
1706         if (new_index != 0) {
1707           // the original index is mapped so we have more work to do
1708           if (!StressLdcRewrite && new_index <= max_jubyte) {
1709             // The new value can still use ldc instead of ldc_w
1710             // unless we are trying to stress ldc -> ldc_w rewriting
1711             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1712               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1713               bcp, cp_index, new_index));
1714             *(bcp + 1) = new_index;
1715           } else {
1716             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1717               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1718               Bytecodes::name(c), bcp, cp_index, new_index));
1719             // the new value needs ldc_w instead of ldc
1720             u_char inst_buffer[4]; // max instruction size is 4 bytes
1721             bcp = (address)inst_buffer;
1722             // construct new instruction sequence
1723             *bcp = Bytecodes::_ldc_w;
1724             bcp++;
1725             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1726             // See comment below for difference between put_Java_u2()
1727             // and put_native_u2().
1728             Bytes::put_Java_u2(bcp, new_index);
1729 
1730             Relocator rc(method, NULL /* no RelocatorListener needed */);
1731             methodHandle m;
1732             {
1733               Pause_No_Safepoint_Verifier pnsv(&nsv);
1734 
1735               // ldc is 2 bytes and ldc_w is 3 bytes
1736               m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1737             }
1738 
1739             // return the new method so that the caller can update
1740             // the containing class
1741             *new_method_p = method = m;
1742             // switch our bytecode processing loop from the old method
1743             // to the new method
1744             code_base = method->code_base();
1745             code_length = method->code_size();
1746             bcp = code_base + bci;
1747             c = (Bytecodes::Code)(*bcp);
1748             bc_length = Bytecodes::length_for(c);
1749             assert(bc_length != 0, "sanity check");
1750           } // end we need ldc_w instead of ldc
1751         } // end if there is a mapped index
1752       } break;
1753 
1754       // these bytecodes have a two-byte constant pool index
1755       case Bytecodes::_anewarray      : // fall through
1756       case Bytecodes::_checkcast      : // fall through
1757       case Bytecodes::_getfield       : // fall through
1758       case Bytecodes::_getstatic      : // fall through
1759       case Bytecodes::_instanceof     : // fall through
1760       case Bytecodes::_invokedynamic  : // fall through
1761       case Bytecodes::_invokeinterface: // fall through
1762       case Bytecodes::_invokespecial  : // fall through
1763       case Bytecodes::_invokestatic   : // fall through
1764       case Bytecodes::_invokevirtual  : // fall through
1765       case Bytecodes::_ldc_w          : // fall through
1766       case Bytecodes::_ldc2_w         : // fall through
1767       case Bytecodes::_multianewarray : // fall through
1768       case Bytecodes::_new            : // fall through
1769       case Bytecodes::_putfield       : // fall through
1770       case Bytecodes::_putstatic      :
1771       {
1772         address p = bcp + 1;
1773         int cp_index = Bytes::get_Java_u2(p);
1774         int new_index = find_new_index(cp_index);
1775         if (new_index != 0) {
1776           // the original index is mapped so update w/ new value
1777           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1778             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1779             bcp, cp_index, new_index));
1780           // Rewriter::rewrite_method() uses put_native_u2() in this
1781           // situation because it is reusing the constant pool index
1782           // location for a native index into the ConstantPoolCache.
1783           // Since we are updating the constant pool index prior to
1784           // verification and ConstantPoolCache initialization, we
1785           // need to keep the new index in Java byte order.
1786           Bytes::put_Java_u2(p, new_index);
1787         }
1788       } break;
1789     }
1790   } // end for each bytecode
1791 
1792   // We also need to rewrite the parameter name indexes, if there is
1793   // method parameter data present
1794   if(method->has_method_parameters()) {
1795     const int len = method->method_parameters_length();
1796     MethodParametersElement* elem = method->method_parameters_start();
1797 
1798     for (int i = 0; i < len; i++) {
1799       const u2 cp_index = elem[i].name_cp_index;
1800       const u2 new_cp_index = find_new_index(cp_index);
1801       if (new_cp_index != 0) {
1802         elem[i].name_cp_index = new_cp_index;
1803       }
1804     }
1805   }
1806 } // end rewrite_cp_refs_in_method()
1807 
1808 
1809 // Rewrite constant pool references in the class_annotations field.
1810 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1811        instanceKlassHandle scratch_class, TRAPS) {
1812 
1813   AnnotationArray* class_annotations = scratch_class->class_annotations();
1814   if (class_annotations == NULL || class_annotations->length() == 0) {
1815     // no class_annotations so nothing to do
1816     return true;
1817   }
1818 
1819   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1820     ("class_annotations length=%d", class_annotations->length()));
1821 
1822   int byte_i = 0;  // byte index into class_annotations
1823   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1824            THREAD);
1825 }
1826 
1827 
1828 // Rewrite constant pool references in an annotations typeArray. This
1829 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1830 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1831 //
1832 // annotations_typeArray {
1833 //   u2 num_annotations;
1834 //   annotation annotations[num_annotations];
1835 // }
1836 //
1837 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1838        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1839 
1840   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1841     // not enough room for num_annotations field
1842     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1843       ("length() is too small for num_annotations field"));
1844     return false;
1845   }
1846 
1847   u2 num_annotations = Bytes::get_Java_u2((address)
1848                          annotations_typeArray->adr_at(byte_i_ref));
1849   byte_i_ref += 2;
1850 
1851   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1852     ("num_annotations=%d", num_annotations));
1853 
1854   int calc_num_annotations = 0;
1855   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1856     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1857            byte_i_ref, THREAD)) {
1858       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1859         ("bad annotation_struct at %d", calc_num_annotations));
1860       // propagate failure back to caller
1861       return false;
1862     }
1863   }
1864   assert(num_annotations == calc_num_annotations, "sanity check");
1865 
1866   return true;
1867 } // end rewrite_cp_refs_in_annotations_typeArray()
1868 
1869 
1870 // Rewrite constant pool references in the annotation struct portion of
1871 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1872 // the 2nd-edition of the VM spec:
1873 //
1874 // struct annotation {
1875 //   u2 type_index;
1876 //   u2 num_element_value_pairs;
1877 //   {
1878 //     u2 element_name_index;
1879 //     element_value value;
1880 //   } element_value_pairs[num_element_value_pairs];
1881 // }
1882 //
1883 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1884        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1885   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1886     // not enough room for smallest annotation_struct
1887     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1888       ("length() is too small for annotation_struct"));
1889     return false;
1890   }
1891 
1892   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1893                     byte_i_ref, "mapped old type_index=%d", THREAD);
1894 
1895   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1896                                  annotations_typeArray->adr_at(byte_i_ref));
1897   byte_i_ref += 2;
1898 
1899   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1900     ("type_index=%d  num_element_value_pairs=%d", type_index,
1901     num_element_value_pairs));
1902 
1903   int calc_num_element_value_pairs = 0;
1904   for (; calc_num_element_value_pairs < num_element_value_pairs;
1905        calc_num_element_value_pairs++) {
1906     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1907       // not enough room for another element_name_index, let alone
1908       // the rest of another component
1909       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1910         ("length() is too small for element_name_index"));
1911       return false;
1912     }
1913 
1914     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1915                               annotations_typeArray, byte_i_ref,
1916                               "mapped old element_name_index=%d", THREAD);
1917 
1918     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1919       ("element_name_index=%d", element_name_index));
1920 
1921     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1922            byte_i_ref, THREAD)) {
1923       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1924         ("bad element_value at %d", calc_num_element_value_pairs));
1925       // propagate failure back to caller
1926       return false;
1927     }
1928   } // end for each component
1929   assert(num_element_value_pairs == calc_num_element_value_pairs,
1930     "sanity check");
1931 
1932   return true;
1933 } // end rewrite_cp_refs_in_annotation_struct()
1934 
1935 
1936 // Rewrite a constant pool reference at the current position in
1937 // annotations_typeArray if needed. Returns the original constant
1938 // pool reference if a rewrite was not needed or the new constant
1939 // pool reference if a rewrite was needed.
1940 PRAGMA_DIAG_PUSH
1941 PRAGMA_FORMAT_NONLITERAL_IGNORED
1942 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1943      AnnotationArray* annotations_typeArray, int &byte_i_ref,
1944      const char * trace_mesg, TRAPS) {
1945 
1946   address cp_index_addr = (address)
1947     annotations_typeArray->adr_at(byte_i_ref);
1948   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1949   u2 new_cp_index = find_new_index(old_cp_index);
1950   if (new_cp_index != 0) {
1951     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1952     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1953     old_cp_index = new_cp_index;
1954   }
1955   byte_i_ref += 2;
1956   return old_cp_index;
1957 }
1958 PRAGMA_DIAG_POP
1959 
1960 
1961 // Rewrite constant pool references in the element_value portion of an
1962 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1963 // the 2nd-edition of the VM spec:
1964 //
1965 // struct element_value {
1966 //   u1 tag;
1967 //   union {
1968 //     u2 const_value_index;
1969 //     {
1970 //       u2 type_name_index;
1971 //       u2 const_name_index;
1972 //     } enum_const_value;
1973 //     u2 class_info_index;
1974 //     annotation annotation_value;
1975 //     struct {
1976 //       u2 num_values;
1977 //       element_value values[num_values];
1978 //     } array_value;
1979 //   } value;
1980 // }
1981 //
1982 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1983        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1984 
1985   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1986     // not enough room for a tag let alone the rest of an element_value
1987     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1988       ("length() is too small for a tag"));
1989     return false;
1990   }
1991 
1992   u1 tag = annotations_typeArray->at(byte_i_ref);
1993   byte_i_ref++;
1994   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1995 
1996   switch (tag) {
1997     // These BaseType tag values are from Table 4.2 in VM spec:
1998     case 'B':  // byte
1999     case 'C':  // char
2000     case 'D':  // double
2001     case 'F':  // float
2002     case 'I':  // int
2003     case 'J':  // long
2004     case 'S':  // short
2005     case 'Z':  // boolean
2006 
2007     // The remaining tag values are from Table 4.8 in the 2nd-edition of
2008     // the VM spec:
2009     case 's':
2010     {
2011       // For the above tag values (including the BaseType values),
2012       // value.const_value_index is right union field.
2013 
2014       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2015         // not enough room for a const_value_index
2016         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2017           ("length() is too small for a const_value_index"));
2018         return false;
2019       }
2020 
2021       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2022                                annotations_typeArray, byte_i_ref,
2023                                "mapped old const_value_index=%d", THREAD);
2024 
2025       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2026         ("const_value_index=%d", const_value_index));
2027     } break;
2028 
2029     case 'e':
2030     {
2031       // for the above tag value, value.enum_const_value is right union field
2032 
2033       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2034         // not enough room for a enum_const_value
2035         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2036           ("length() is too small for a enum_const_value"));
2037         return false;
2038       }
2039 
2040       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2041                              annotations_typeArray, byte_i_ref,
2042                              "mapped old type_name_index=%d", THREAD);
2043 
2044       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2045                               annotations_typeArray, byte_i_ref,
2046                               "mapped old const_name_index=%d", THREAD);
2047 
2048       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2049         ("type_name_index=%d  const_name_index=%d", type_name_index,
2050         const_name_index));
2051     } break;
2052 
2053     case 'c':
2054     {
2055       // for the above tag value, value.class_info_index is right union field
2056 
2057       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2058         // not enough room for a class_info_index
2059         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2060           ("length() is too small for a class_info_index"));
2061         return false;
2062       }
2063 
2064       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2065                               annotations_typeArray, byte_i_ref,
2066                               "mapped old class_info_index=%d", THREAD);
2067 
2068       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2069         ("class_info_index=%d", class_info_index));
2070     } break;
2071 
2072     case '@':
2073       // For the above tag value, value.attr_value is the right union
2074       // field. This is a nested annotation.
2075       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2076              byte_i_ref, THREAD)) {
2077         // propagate failure back to caller
2078         return false;
2079       }
2080       break;
2081 
2082     case '[':
2083     {
2084       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2085         // not enough room for a num_values field
2086         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2087           ("length() is too small for a num_values field"));
2088         return false;
2089       }
2090 
2091       // For the above tag value, value.array_value is the right union
2092       // field. This is an array of nested element_value.
2093       u2 num_values = Bytes::get_Java_u2((address)
2094                         annotations_typeArray->adr_at(byte_i_ref));
2095       byte_i_ref += 2;
2096       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
2097 
2098       int calc_num_values = 0;
2099       for (; calc_num_values < num_values; calc_num_values++) {
2100         if (!rewrite_cp_refs_in_element_value(
2101                annotations_typeArray, byte_i_ref, THREAD)) {
2102           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2103             ("bad nested element_value at %d", calc_num_values));
2104           // propagate failure back to caller
2105           return false;
2106         }
2107       }
2108       assert(num_values == calc_num_values, "sanity check");
2109     } break;
2110 
2111     default:
2112       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
2113       return false;
2114   } // end decode tag field
2115 
2116   return true;
2117 } // end rewrite_cp_refs_in_element_value()
2118 
2119 
2120 // Rewrite constant pool references in a fields_annotations field.
2121 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2122        instanceKlassHandle scratch_class, TRAPS) {
2123 
2124   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2125 
2126   if (fields_annotations == NULL || fields_annotations->length() == 0) {
2127     // no fields_annotations so nothing to do
2128     return true;
2129   }
2130 
2131   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2132     ("fields_annotations length=%d", fields_annotations->length()));
2133 
2134   for (int i = 0; i < fields_annotations->length(); i++) {
2135     AnnotationArray* field_annotations = fields_annotations->at(i);
2136     if (field_annotations == NULL || field_annotations->length() == 0) {
2137       // this field does not have any annotations so skip it
2138       continue;
2139     }
2140 
2141     int byte_i = 0;  // byte index into field_annotations
2142     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2143            THREAD)) {
2144       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2145         ("bad field_annotations at %d", i));
2146       // propagate failure back to caller
2147       return false;
2148     }
2149   }
2150 
2151   return true;
2152 } // end rewrite_cp_refs_in_fields_annotations()
2153 
2154 
2155 // Rewrite constant pool references in a methods_annotations field.
2156 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2157        instanceKlassHandle scratch_class, TRAPS) {
2158 
2159   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2160     Method* m = scratch_class->methods()->at(i);
2161     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2162 
2163     if (method_annotations == NULL || method_annotations->length() == 0) {
2164       // this method does not have any annotations so skip it
2165       continue;
2166     }
2167 
2168     int byte_i = 0;  // byte index into method_annotations
2169     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2170            THREAD)) {
2171       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2172         ("bad method_annotations at %d", i));
2173       // propagate failure back to caller
2174       return false;
2175     }
2176   }
2177 
2178   return true;
2179 } // end rewrite_cp_refs_in_methods_annotations()
2180 
2181 
2182 // Rewrite constant pool references in a methods_parameter_annotations
2183 // field. This "structure" is adapted from the
2184 // RuntimeVisibleParameterAnnotations_attribute described in section
2185 // 4.8.17 of the 2nd-edition of the VM spec:
2186 //
2187 // methods_parameter_annotations_typeArray {
2188 //   u1 num_parameters;
2189 //   {
2190 //     u2 num_annotations;
2191 //     annotation annotations[num_annotations];
2192 //   } parameter_annotations[num_parameters];
2193 // }
2194 //
2195 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2196        instanceKlassHandle scratch_class, TRAPS) {
2197 
2198   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2199     Method* m = scratch_class->methods()->at(i);
2200     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2201     if (method_parameter_annotations == NULL
2202         || method_parameter_annotations->length() == 0) {
2203       // this method does not have any parameter annotations so skip it
2204       continue;
2205     }
2206 
2207     if (method_parameter_annotations->length() < 1) {
2208       // not enough room for a num_parameters field
2209       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2210         ("length() is too small for a num_parameters field at %d", i));
2211       return false;
2212     }
2213 
2214     int byte_i = 0;  // byte index into method_parameter_annotations
2215 
2216     u1 num_parameters = method_parameter_annotations->at(byte_i);
2217     byte_i++;
2218 
2219     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2220       ("num_parameters=%d", num_parameters));
2221 
2222     int calc_num_parameters = 0;
2223     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2224       if (!rewrite_cp_refs_in_annotations_typeArray(
2225              method_parameter_annotations, byte_i, THREAD)) {
2226         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2227           ("bad method_parameter_annotations at %d", calc_num_parameters));
2228         // propagate failure back to caller
2229         return false;
2230       }
2231     }
2232     assert(num_parameters == calc_num_parameters, "sanity check");
2233   }
2234 
2235   return true;
2236 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2237 
2238 
2239 // Rewrite constant pool references in a methods_default_annotations
2240 // field. This "structure" is adapted from the AnnotationDefault_attribute
2241 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2242 //
2243 // methods_default_annotations_typeArray {
2244 //   element_value default_value;
2245 // }
2246 //
2247 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2248        instanceKlassHandle scratch_class, TRAPS) {
2249 
2250   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2251     Method* m = scratch_class->methods()->at(i);
2252     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2253     if (method_default_annotations == NULL
2254         || method_default_annotations->length() == 0) {
2255       // this method does not have any default annotations so skip it
2256       continue;
2257     }
2258 
2259     int byte_i = 0;  // byte index into method_default_annotations
2260 
2261     if (!rewrite_cp_refs_in_element_value(
2262            method_default_annotations, byte_i, THREAD)) {
2263       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2264         ("bad default element_value at %d", i));
2265       // propagate failure back to caller
2266       return false;
2267     }
2268   }
2269 
2270   return true;
2271 } // end rewrite_cp_refs_in_methods_default_annotations()
2272 
2273 
2274 // Rewrite constant pool references in a class_type_annotations field.
2275 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2276        instanceKlassHandle scratch_class, TRAPS) {
2277 
2278   AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2279   if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2280     // no class_type_annotations so nothing to do
2281     return true;
2282   }
2283 
2284   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2285     ("class_type_annotations length=%d", class_type_annotations->length()));
2286 
2287   int byte_i = 0;  // byte index into class_type_annotations
2288   return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2289       byte_i, "ClassFile", THREAD);
2290 } // end rewrite_cp_refs_in_class_type_annotations()
2291 
2292 
2293 // Rewrite constant pool references in a fields_type_annotations field.
2294 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2295        instanceKlassHandle scratch_class, TRAPS) {
2296 
2297   Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2298   if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2299     // no fields_type_annotations so nothing to do
2300     return true;
2301   }
2302 
2303   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2304     ("fields_type_annotations length=%d", fields_type_annotations->length()));
2305 
2306   for (int i = 0; i < fields_type_annotations->length(); i++) {
2307     AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2308     if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2309       // this field does not have any annotations so skip it
2310       continue;
2311     }
2312 
2313     int byte_i = 0;  // byte index into field_type_annotations
2314     if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2315            byte_i, "field_info", THREAD)) {
2316       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2317         ("bad field_type_annotations at %d", i));
2318       // propagate failure back to caller
2319       return false;
2320     }
2321   }
2322 
2323   return true;
2324 } // end rewrite_cp_refs_in_fields_type_annotations()
2325 
2326 
2327 // Rewrite constant pool references in a methods_type_annotations field.
2328 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2329        instanceKlassHandle scratch_class, TRAPS) {
2330 
2331   for (int i = 0; i < scratch_class->methods()->length(); i++) {
2332     Method* m = scratch_class->methods()->at(i);
2333     AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2334 
2335     if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2336       // this method does not have any annotations so skip it
2337       continue;
2338     }
2339 
2340     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2341         ("methods type_annotations length=%d", method_type_annotations->length()));
2342 
2343     int byte_i = 0;  // byte index into method_type_annotations
2344     if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2345            byte_i, "method_info", THREAD)) {
2346       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2347         ("bad method_type_annotations at %d", i));
2348       // propagate failure back to caller
2349       return false;
2350     }
2351   }
2352 
2353   return true;
2354 } // end rewrite_cp_refs_in_methods_type_annotations()
2355 
2356 
2357 // Rewrite constant pool references in a type_annotations
2358 // field. This "structure" is adapted from the
2359 // RuntimeVisibleTypeAnnotations_attribute described in
2360 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2361 //
2362 // type_annotations_typeArray {
2363 //   u2              num_annotations;
2364 //   type_annotation annotations[num_annotations];
2365 // }
2366 //
2367 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2368        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2369        const char * location_mesg, TRAPS) {
2370 
2371   if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2372     // not enough room for num_annotations field
2373     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2374       ("length() is too small for num_annotations field"));
2375     return false;
2376   }
2377 
2378   u2 num_annotations = Bytes::get_Java_u2((address)
2379                          type_annotations_typeArray->adr_at(byte_i_ref));
2380   byte_i_ref += 2;
2381 
2382   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2383     ("num_type_annotations=%d", num_annotations));
2384 
2385   int calc_num_annotations = 0;
2386   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2387     if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2388            byte_i_ref, location_mesg, THREAD)) {
2389       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2390         ("bad type_annotation_struct at %d", calc_num_annotations));
2391       // propagate failure back to caller
2392       return false;
2393     }
2394   }
2395   assert(num_annotations == calc_num_annotations, "sanity check");
2396 
2397   if (byte_i_ref != type_annotations_typeArray->length()) {
2398     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2399       ("read wrong amount of bytes at end of processing "
2400        "type_annotations_typeArray (%d of %d bytes were read)",
2401        byte_i_ref, type_annotations_typeArray->length()));
2402     return false;
2403   }
2404 
2405   return true;
2406 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2407 
2408 
2409 // Rewrite constant pool references in a type_annotation
2410 // field. This "structure" is adapted from the
2411 // RuntimeVisibleTypeAnnotations_attribute described in
2412 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2413 //
2414 // type_annotation {
2415 //   u1 target_type;
2416 //   union {
2417 //     type_parameter_target;
2418 //     supertype_target;
2419 //     type_parameter_bound_target;
2420 //     empty_target;
2421 //     method_formal_parameter_target;
2422 //     throws_target;
2423 //     localvar_target;
2424 //     catch_target;
2425 //     offset_target;
2426 //     type_argument_target;
2427 //   } target_info;
2428 //   type_path target_path;
2429 //   annotation anno;
2430 // }
2431 //
2432 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2433        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2434        const char * location_mesg, TRAPS) {
2435 
2436   if (!skip_type_annotation_target(type_annotations_typeArray,
2437          byte_i_ref, location_mesg, THREAD)) {
2438     return false;
2439   }
2440 
2441   if (!skip_type_annotation_type_path(type_annotations_typeArray,
2442          byte_i_ref, THREAD)) {
2443     return false;
2444   }
2445 
2446   if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2447          byte_i_ref, THREAD)) {
2448     return false;
2449   }
2450 
2451   return true;
2452 } // end rewrite_cp_refs_in_type_annotation_struct()
2453 
2454 
2455 // Read, verify and skip over the target_type and target_info part
2456 // so that rewriting can continue in the later parts of the struct.
2457 //
2458 // u1 target_type;
2459 // union {
2460 //   type_parameter_target;
2461 //   supertype_target;
2462 //   type_parameter_bound_target;
2463 //   empty_target;
2464 //   method_formal_parameter_target;
2465 //   throws_target;
2466 //   localvar_target;
2467 //   catch_target;
2468 //   offset_target;
2469 //   type_argument_target;
2470 // } target_info;
2471 //
2472 bool VM_RedefineClasses::skip_type_annotation_target(
2473        AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2474        const char * location_mesg, TRAPS) {
2475 
2476   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2477     // not enough room for a target_type let alone the rest of a type_annotation
2478     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2479       ("length() is too small for a target_type"));
2480     return false;
2481   }
2482 
2483   u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2484   byte_i_ref += 1;
2485   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("target_type=0x%.2x", target_type));
2486   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("location=%s", location_mesg));
2487 
2488   // Skip over target_info
2489   switch (target_type) {
2490     case 0x00:
2491     // kind: type parameter declaration of generic class or interface
2492     // location: ClassFile
2493     case 0x01:
2494     // kind: type parameter declaration of generic method or constructor
2495     // location: method_info
2496 
2497     {
2498       // struct:
2499       // type_parameter_target {
2500       //   u1 type_parameter_index;
2501       // }
2502       //
2503       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2504         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2505           ("length() is too small for a type_parameter_target"));
2506         return false;
2507       }
2508 
2509       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2510       byte_i_ref += 1;
2511 
2512       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2513         ("type_parameter_target: type_parameter_index=%d",
2514          type_parameter_index));
2515     } break;
2516 
2517     case 0x10:
2518     // kind: type in extends clause of class or interface declaration
2519     //       (including the direct superclass of an anonymous class declaration),
2520     //       or in implements clause of interface declaration
2521     // location: ClassFile
2522 
2523     {
2524       // struct:
2525       // supertype_target {
2526       //   u2 supertype_index;
2527       // }
2528       //
2529       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2530         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2531           ("length() is too small for a supertype_target"));
2532         return false;
2533       }
2534 
2535       u2 supertype_index = Bytes::get_Java_u2((address)
2536                              type_annotations_typeArray->adr_at(byte_i_ref));
2537       byte_i_ref += 2;
2538 
2539       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2540         ("supertype_target: supertype_index=%d", supertype_index));
2541     } break;
2542 
2543     case 0x11:
2544     // kind: type in bound of type parameter declaration of generic class or interface
2545     // location: ClassFile
2546     case 0x12:
2547     // kind: type in bound of type parameter declaration of generic method or constructor
2548     // location: method_info
2549 
2550     {
2551       // struct:
2552       // type_parameter_bound_target {
2553       //   u1 type_parameter_index;
2554       //   u1 bound_index;
2555       // }
2556       //
2557       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2558         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2559           ("length() is too small for a type_parameter_bound_target"));
2560         return false;
2561       }
2562 
2563       u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2564       byte_i_ref += 1;
2565       u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2566       byte_i_ref += 1;
2567 
2568       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2569         ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d",
2570          type_parameter_index, bound_index));
2571     } break;
2572 
2573     case 0x13:
2574     // kind: type in field declaration
2575     // location: field_info
2576     case 0x14:
2577     // kind: return type of method, or type of newly constructed object
2578     // location: method_info
2579     case 0x15:
2580     // kind: receiver type of method or constructor
2581     // location: method_info
2582 
2583     {
2584       // struct:
2585       // empty_target {
2586       // }
2587       //
2588       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2589         ("empty_target"));
2590     } break;
2591 
2592     case 0x16:
2593     // kind: type in formal parameter declaration of method, constructor, or lambda expression
2594     // location: method_info
2595 
2596     {
2597       // struct:
2598       // formal_parameter_target {
2599       //   u1 formal_parameter_index;
2600       // }
2601       //
2602       if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2603         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2604           ("length() is too small for a formal_parameter_target"));
2605         return false;
2606       }
2607 
2608       u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2609       byte_i_ref += 1;
2610 
2611       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2612         ("formal_parameter_target: formal_parameter_index=%d",
2613          formal_parameter_index));
2614     } break;
2615 
2616     case 0x17:
2617     // kind: type in throws clause of method or constructor
2618     // location: method_info
2619 
2620     {
2621       // struct:
2622       // throws_target {
2623       //   u2 throws_type_index
2624       // }
2625       //
2626       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2627         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2628           ("length() is too small for a throws_target"));
2629         return false;
2630       }
2631 
2632       u2 throws_type_index = Bytes::get_Java_u2((address)
2633                                type_annotations_typeArray->adr_at(byte_i_ref));
2634       byte_i_ref += 2;
2635 
2636       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2637         ("throws_target: throws_type_index=%d", throws_type_index));
2638     } break;
2639 
2640     case 0x40:
2641     // kind: type in local variable declaration
2642     // location: Code
2643     case 0x41:
2644     // kind: type in resource variable declaration
2645     // location: Code
2646 
2647     {
2648       // struct:
2649       // localvar_target {
2650       //   u2 table_length;
2651       //   struct {
2652       //     u2 start_pc;
2653       //     u2 length;
2654       //     u2 index;
2655       //   } table[table_length];
2656       // }
2657       //
2658       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2659         // not enough room for a table_length let alone the rest of a localvar_target
2660         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2661           ("length() is too small for a localvar_target table_length"));
2662         return false;
2663       }
2664 
2665       u2 table_length = Bytes::get_Java_u2((address)
2666                           type_annotations_typeArray->adr_at(byte_i_ref));
2667       byte_i_ref += 2;
2668 
2669       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2670         ("localvar_target: table_length=%d", table_length));
2671 
2672       int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2673       int table_size = table_length * table_struct_size;
2674 
2675       if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2676         // not enough room for a table
2677         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2678           ("length() is too small for a table array of length %d", table_length));
2679         return false;
2680       }
2681 
2682       // Skip over table
2683       byte_i_ref += table_size;
2684     } break;
2685 
2686     case 0x42:
2687     // kind: type in exception parameter declaration
2688     // location: Code
2689 
2690     {
2691       // struct:
2692       // catch_target {
2693       //   u2 exception_table_index;
2694       // }
2695       //
2696       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2697         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2698           ("length() is too small for a catch_target"));
2699         return false;
2700       }
2701 
2702       u2 exception_table_index = Bytes::get_Java_u2((address)
2703                                    type_annotations_typeArray->adr_at(byte_i_ref));
2704       byte_i_ref += 2;
2705 
2706       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2707         ("catch_target: exception_table_index=%d", exception_table_index));
2708     } break;
2709 
2710     case 0x43:
2711     // kind: type in instanceof expression
2712     // location: Code
2713     case 0x44:
2714     // kind: type in new expression
2715     // location: Code
2716     case 0x45:
2717     // kind: type in method reference expression using ::new
2718     // location: Code
2719     case 0x46:
2720     // kind: type in method reference expression using ::Identifier
2721     // location: Code
2722 
2723     {
2724       // struct:
2725       // offset_target {
2726       //   u2 offset;
2727       // }
2728       //
2729       if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2730         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2731           ("length() is too small for a offset_target"));
2732         return false;
2733       }
2734 
2735       u2 offset = Bytes::get_Java_u2((address)
2736                     type_annotations_typeArray->adr_at(byte_i_ref));
2737       byte_i_ref += 2;
2738 
2739       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2740         ("offset_target: offset=%d", offset));
2741     } break;
2742 
2743     case 0x47:
2744     // kind: type in cast expression
2745     // location: Code
2746     case 0x48:
2747     // kind: type argument for generic constructor in new expression or
2748     //       explicit constructor invocation statement
2749     // location: Code
2750     case 0x49:
2751     // kind: type argument for generic method in method invocation expression
2752     // location: Code
2753     case 0x4A:
2754     // kind: type argument for generic constructor in method reference expression using ::new
2755     // location: Code
2756     case 0x4B:
2757     // kind: type argument for generic method in method reference expression using ::Identifier
2758     // location: Code
2759 
2760     {
2761       // struct:
2762       // type_argument_target {
2763       //   u2 offset;
2764       //   u1 type_argument_index;
2765       // }
2766       //
2767       if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2768         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2769           ("length() is too small for a type_argument_target"));
2770         return false;
2771       }
2772 
2773       u2 offset = Bytes::get_Java_u2((address)
2774                     type_annotations_typeArray->adr_at(byte_i_ref));
2775       byte_i_ref += 2;
2776       u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2777       byte_i_ref += 1;
2778 
2779       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2780         ("type_argument_target: offset=%d, type_argument_index=%d",
2781          offset, type_argument_index));
2782     } break;
2783 
2784     default:
2785       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2786         ("unknown target_type"));
2787 #ifdef ASSERT
2788       ShouldNotReachHere();
2789 #endif
2790       return false;
2791   }
2792 
2793   return true;
2794 } // end skip_type_annotation_target()
2795 
2796 
2797 // Read, verify and skip over the type_path part so that rewriting
2798 // can continue in the later parts of the struct.
2799 //
2800 // type_path {
2801 //   u1 path_length;
2802 //   {
2803 //     u1 type_path_kind;
2804 //     u1 type_argument_index;
2805 //   } path[path_length];
2806 // }
2807 //
2808 bool VM_RedefineClasses::skip_type_annotation_type_path(
2809        AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2810 
2811   if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2812     // not enough room for a path_length let alone the rest of the type_path
2813     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2814       ("length() is too small for a type_path"));
2815     return false;
2816   }
2817 
2818   u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2819   byte_i_ref += 1;
2820 
2821   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2822     ("type_path: path_length=%d", path_length));
2823 
2824   int calc_path_length = 0;
2825   for (; calc_path_length < path_length; calc_path_length++) {
2826     if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2827       // not enough room for a path
2828       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2829         ("length() is too small for path entry %d of %d",
2830          calc_path_length, path_length));
2831       return false;
2832     }
2833 
2834     u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2835     byte_i_ref += 1;
2836     u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2837     byte_i_ref += 1;
2838 
2839     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2840       ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2841        calc_path_length, type_path_kind, type_argument_index));
2842 
2843     if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2844       // not enough room for a path
2845       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2846         ("inconsistent type_path values"));
2847       return false;
2848     }
2849   }
2850   assert(path_length == calc_path_length, "sanity check");
2851 
2852   return true;
2853 } // end skip_type_annotation_type_path()
2854 
2855 
2856 // Rewrite constant pool references in the method's stackmap table.
2857 // These "structures" are adapted from the StackMapTable_attribute that
2858 // is described in section 4.8.4 of the 6.0 version of the VM spec
2859 // (dated 2005.10.26):
2860 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2861 //
2862 // stack_map {
2863 //   u2 number_of_entries;
2864 //   stack_map_frame entries[number_of_entries];
2865 // }
2866 //
2867 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2868        methodHandle method, TRAPS) {
2869 
2870   if (!method->has_stackmap_table()) {
2871     return;
2872   }
2873 
2874   AnnotationArray* stackmap_data = method->stackmap_data();
2875   address stackmap_p = (address)stackmap_data->adr_at(0);
2876   address stackmap_end = stackmap_p + stackmap_data->length();
2877 
2878   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2879   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2880   stackmap_p += 2;
2881 
2882   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2883     ("number_of_entries=%u", number_of_entries));
2884 
2885   // walk through each stack_map_frame
2886   u2 calc_number_of_entries = 0;
2887   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2888     // The stack_map_frame structure is a u1 frame_type followed by
2889     // 0 or more bytes of data:
2890     //
2891     // union stack_map_frame {
2892     //   same_frame;
2893     //   same_locals_1_stack_item_frame;
2894     //   same_locals_1_stack_item_frame_extended;
2895     //   chop_frame;
2896     //   same_frame_extended;
2897     //   append_frame;
2898     //   full_frame;
2899     // }
2900 
2901     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2902     u1 frame_type = *stackmap_p;
2903     stackmap_p++;
2904 
2905     // same_frame {
2906     //   u1 frame_type = SAME; /* 0-63 */
2907     // }
2908     if (frame_type <= 63) {
2909       // nothing more to do for same_frame
2910     }
2911 
2912     // same_locals_1_stack_item_frame {
2913     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2914     //   verification_type_info stack[1];
2915     // }
2916     else if (frame_type >= 64 && frame_type <= 127) {
2917       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2918         calc_number_of_entries, frame_type, THREAD);
2919     }
2920 
2921     // reserved for future use
2922     else if (frame_type >= 128 && frame_type <= 246) {
2923       // nothing more to do for reserved frame_types
2924     }
2925 
2926     // same_locals_1_stack_item_frame_extended {
2927     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2928     //   u2 offset_delta;
2929     //   verification_type_info stack[1];
2930     // }
2931     else if (frame_type == 247) {
2932       stackmap_p += 2;
2933       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2934         calc_number_of_entries, frame_type, THREAD);
2935     }
2936 
2937     // chop_frame {
2938     //   u1 frame_type = CHOP; /* 248-250 */
2939     //   u2 offset_delta;
2940     // }
2941     else if (frame_type >= 248 && frame_type <= 250) {
2942       stackmap_p += 2;
2943     }
2944 
2945     // same_frame_extended {
2946     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2947     //   u2 offset_delta;
2948     // }
2949     else if (frame_type == 251) {
2950       stackmap_p += 2;
2951     }
2952 
2953     // append_frame {
2954     //   u1 frame_type = APPEND; /* 252-254 */
2955     //   u2 offset_delta;
2956     //   verification_type_info locals[frame_type - 251];
2957     // }
2958     else if (frame_type >= 252 && frame_type <= 254) {
2959       assert(stackmap_p + 2 <= stackmap_end,
2960         "no room for offset_delta");
2961       stackmap_p += 2;
2962       u1 len = frame_type - 251;
2963       for (u1 i = 0; i < len; i++) {
2964         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2965           calc_number_of_entries, frame_type, THREAD);
2966       }
2967     }
2968 
2969     // full_frame {
2970     //   u1 frame_type = FULL_FRAME; /* 255 */
2971     //   u2 offset_delta;
2972     //   u2 number_of_locals;
2973     //   verification_type_info locals[number_of_locals];
2974     //   u2 number_of_stack_items;
2975     //   verification_type_info stack[number_of_stack_items];
2976     // }
2977     else if (frame_type == 255) {
2978       assert(stackmap_p + 2 + 2 <= stackmap_end,
2979         "no room for smallest full_frame");
2980       stackmap_p += 2;
2981 
2982       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2983       stackmap_p += 2;
2984 
2985       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2986         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2987           calc_number_of_entries, frame_type, THREAD);
2988       }
2989 
2990       // Use the largest size for the number_of_stack_items, but only get
2991       // the right number of bytes.
2992       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2993       stackmap_p += 2;
2994 
2995       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2996         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2997           calc_number_of_entries, frame_type, THREAD);
2998       }
2999     }
3000   } // end while there is a stack_map_frame
3001   assert(number_of_entries == calc_number_of_entries, "sanity check");
3002 } // end rewrite_cp_refs_in_stack_map_table()
3003 
3004 
3005 // Rewrite constant pool references in the verification type info
3006 // portion of the method's stackmap table. These "structures" are
3007 // adapted from the StackMapTable_attribute that is described in
3008 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3009 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3010 //
3011 // The verification_type_info structure is a u1 tag followed by 0 or
3012 // more bytes of data:
3013 //
3014 // union verification_type_info {
3015 //   Top_variable_info;
3016 //   Integer_variable_info;
3017 //   Float_variable_info;
3018 //   Long_variable_info;
3019 //   Double_variable_info;
3020 //   Null_variable_info;
3021 //   UninitializedThis_variable_info;
3022 //   Object_variable_info;
3023 //   Uninitialized_variable_info;
3024 // }
3025 //
3026 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3027        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3028        u1 frame_type, TRAPS) {
3029 
3030   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3031   u1 tag = *stackmap_p_ref;
3032   stackmap_p_ref++;
3033 
3034   switch (tag) {
3035   // Top_variable_info {
3036   //   u1 tag = ITEM_Top; /* 0 */
3037   // }
3038   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3039   case 0:  // fall through
3040 
3041   // Integer_variable_info {
3042   //   u1 tag = ITEM_Integer; /* 1 */
3043   // }
3044   case ITEM_Integer:  // fall through
3045 
3046   // Float_variable_info {
3047   //   u1 tag = ITEM_Float; /* 2 */
3048   // }
3049   case ITEM_Float:  // fall through
3050 
3051   // Double_variable_info {
3052   //   u1 tag = ITEM_Double; /* 3 */
3053   // }
3054   case ITEM_Double:  // fall through
3055 
3056   // Long_variable_info {
3057   //   u1 tag = ITEM_Long; /* 4 */
3058   // }
3059   case ITEM_Long:  // fall through
3060 
3061   // Null_variable_info {
3062   //   u1 tag = ITEM_Null; /* 5 */
3063   // }
3064   case ITEM_Null:  // fall through
3065 
3066   // UninitializedThis_variable_info {
3067   //   u1 tag = ITEM_UninitializedThis; /* 6 */
3068   // }
3069   case ITEM_UninitializedThis:
3070     // nothing more to do for the above tag types
3071     break;
3072 
3073   // Object_variable_info {
3074   //   u1 tag = ITEM_Object; /* 7 */
3075   //   u2 cpool_index;
3076   // }
3077   case ITEM_Object:
3078   {
3079     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3080     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3081     u2 new_cp_index = find_new_index(cpool_index);
3082     if (new_cp_index != 0) {
3083       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3084         ("mapped old cpool_index=%d", cpool_index));
3085       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3086       cpool_index = new_cp_index;
3087     }
3088     stackmap_p_ref += 2;
3089 
3090     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3091       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
3092       frame_type, cpool_index));
3093   } break;
3094 
3095   // Uninitialized_variable_info {
3096   //   u1 tag = ITEM_Uninitialized; /* 8 */
3097   //   u2 offset;
3098   // }
3099   case ITEM_Uninitialized:
3100     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3101     stackmap_p_ref += 2;
3102     break;
3103 
3104   default:
3105     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3106       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
3107     ShouldNotReachHere();
3108     break;
3109   } // end switch (tag)
3110 } // end rewrite_cp_refs_in_verification_type_info()
3111 
3112 
3113 // Change the constant pool associated with klass scratch_class to
3114 // scratch_cp. If shrink is true, then scratch_cp_length elements
3115 // are copied from scratch_cp to a smaller constant pool and the
3116 // smaller constant pool is associated with scratch_class.
3117 void VM_RedefineClasses::set_new_constant_pool(
3118        ClassLoaderData* loader_data,
3119        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
3120        int scratch_cp_length, TRAPS) {
3121   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3122 
3123   // scratch_cp is a merged constant pool and has enough space for a
3124   // worst case merge situation. We want to associate the minimum
3125   // sized constant pool with the klass to save space.
3126   ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3127   constantPoolHandle smaller_cp(THREAD, cp);
3128 
3129   // preserve version() value in the smaller copy
3130   int version = scratch_cp->version();
3131   assert(version != 0, "sanity check");
3132   smaller_cp->set_version(version);
3133 
3134   // attach klass to new constant pool
3135   // reference to the cp holder is needed for copy_operands()
3136   smaller_cp->set_pool_holder(scratch_class());
3137 
3138   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3139   if (HAS_PENDING_EXCEPTION) {
3140     // Exception is handled in the caller
3141     loader_data->add_to_deallocate_list(smaller_cp());
3142     return;
3143   }
3144   scratch_cp = smaller_cp;
3145 
3146   // attach new constant pool to klass
3147   scratch_class->set_constants(scratch_cp());
3148 
3149   int i;  // for portability
3150 
3151   // update each field in klass to use new constant pool indices as needed
3152   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3153     jshort cur_index = fs.name_index();
3154     jshort new_index = find_new_index(cur_index);
3155     if (new_index != 0) {
3156       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3157         ("field-name_index change: %d to %d", cur_index, new_index));
3158       fs.set_name_index(new_index);
3159     }
3160     cur_index = fs.signature_index();
3161     new_index = find_new_index(cur_index);
3162     if (new_index != 0) {
3163       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3164         ("field-signature_index change: %d to %d", cur_index, new_index));
3165       fs.set_signature_index(new_index);
3166     }
3167     cur_index = fs.initval_index();
3168     new_index = find_new_index(cur_index);
3169     if (new_index != 0) {
3170       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3171         ("field-initval_index change: %d to %d", cur_index, new_index));
3172       fs.set_initval_index(new_index);
3173     }
3174     cur_index = fs.generic_signature_index();
3175     new_index = find_new_index(cur_index);
3176     if (new_index != 0) {
3177       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3178         ("field-generic_signature change: %d to %d", cur_index, new_index));
3179       fs.set_generic_signature_index(new_index);
3180     }
3181   } // end for each field
3182 
3183   // Update constant pool indices in the inner classes info to use
3184   // new constant indices as needed. The inner classes info is a
3185   // quadruple:
3186   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3187   InnerClassesIterator iter(scratch_class);
3188   for (; !iter.done(); iter.next()) {
3189     int cur_index = iter.inner_class_info_index();
3190     if (cur_index == 0) {
3191       continue;  // JVM spec. allows null inner class refs so skip it
3192     }
3193     int new_index = find_new_index(cur_index);
3194     if (new_index != 0) {
3195       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3196         ("inner_class_info change: %d to %d", cur_index, new_index));
3197       iter.set_inner_class_info_index(new_index);
3198     }
3199     cur_index = iter.outer_class_info_index();
3200     new_index = find_new_index(cur_index);
3201     if (new_index != 0) {
3202       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3203         ("outer_class_info change: %d to %d", cur_index, new_index));
3204       iter.set_outer_class_info_index(new_index);
3205     }
3206     cur_index = iter.inner_name_index();
3207     new_index = find_new_index(cur_index);
3208     if (new_index != 0) {
3209       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3210         ("inner_name change: %d to %d", cur_index, new_index));
3211       iter.set_inner_name_index(new_index);
3212     }
3213   } // end for each inner class
3214 
3215   // Attach each method in klass to the new constant pool and update
3216   // to use new constant pool indices as needed:
3217   Array<Method*>* methods = scratch_class->methods();
3218   for (i = methods->length() - 1; i >= 0; i--) {
3219     methodHandle method(THREAD, methods->at(i));
3220     method->set_constants(scratch_cp());
3221 
3222     int new_index = find_new_index(method->name_index());
3223     if (new_index != 0) {
3224       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3225         ("method-name_index change: %d to %d", method->name_index(),
3226         new_index));
3227       method->set_name_index(new_index);
3228     }
3229     new_index = find_new_index(method->signature_index());
3230     if (new_index != 0) {
3231       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3232         ("method-signature_index change: %d to %d",
3233         method->signature_index(), new_index));
3234       method->set_signature_index(new_index);
3235     }
3236     new_index = find_new_index(method->generic_signature_index());
3237     if (new_index != 0) {
3238       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3239         ("method-generic_signature_index change: %d to %d",
3240         method->generic_signature_index(), new_index));
3241       method->set_generic_signature_index(new_index);
3242     }
3243 
3244     // Update constant pool indices in the method's checked exception
3245     // table to use new constant indices as needed.
3246     int cext_length = method->checked_exceptions_length();
3247     if (cext_length > 0) {
3248       CheckedExceptionElement * cext_table =
3249         method->checked_exceptions_start();
3250       for (int j = 0; j < cext_length; j++) {
3251         int cur_index = cext_table[j].class_cp_index;
3252         int new_index = find_new_index(cur_index);
3253         if (new_index != 0) {
3254           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3255             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
3256           cext_table[j].class_cp_index = (u2)new_index;
3257         }
3258       } // end for each checked exception table entry
3259     } // end if there are checked exception table entries
3260 
3261     // Update each catch type index in the method's exception table
3262     // to use new constant pool indices as needed. The exception table
3263     // holds quadruple entries of the form:
3264     //   (beg_bci, end_bci, handler_bci, klass_index)
3265 
3266     ExceptionTable ex_table(method());
3267     int ext_length = ex_table.length();
3268 
3269     for (int j = 0; j < ext_length; j ++) {
3270       int cur_index = ex_table.catch_type_index(j);
3271       int new_index = find_new_index(cur_index);
3272       if (new_index != 0) {
3273         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3274           ("ext-klass_index change: %d to %d", cur_index, new_index));
3275         ex_table.set_catch_type_index(j, new_index);
3276       }
3277     } // end for each exception table entry
3278 
3279     // Update constant pool indices in the method's local variable
3280     // table to use new constant indices as needed. The local variable
3281     // table hold sextuple entries of the form:
3282     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3283     int lvt_length = method->localvariable_table_length();
3284     if (lvt_length > 0) {
3285       LocalVariableTableElement * lv_table =
3286         method->localvariable_table_start();
3287       for (int j = 0; j < lvt_length; j++) {
3288         int cur_index = lv_table[j].name_cp_index;
3289         int new_index = find_new_index(cur_index);
3290         if (new_index != 0) {
3291           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3292             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
3293           lv_table[j].name_cp_index = (u2)new_index;
3294         }
3295         cur_index = lv_table[j].descriptor_cp_index;
3296         new_index = find_new_index(cur_index);
3297         if (new_index != 0) {
3298           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3299             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
3300             new_index));
3301           lv_table[j].descriptor_cp_index = (u2)new_index;
3302         }
3303         cur_index = lv_table[j].signature_cp_index;
3304         new_index = find_new_index(cur_index);
3305         if (new_index != 0) {
3306           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3307             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
3308           lv_table[j].signature_cp_index = (u2)new_index;
3309         }
3310       } // end for each local variable table entry
3311     } // end if there are local variable table entries
3312 
3313     rewrite_cp_refs_in_stack_map_table(method, THREAD);
3314   } // end for each method
3315 } // end set_new_constant_pool()
3316 
3317 
3318 // Unevolving classes may point to methods of the_class directly
3319 // from their constant pool caches, itables, and/or vtables. We
3320 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3321 // to fix up these pointers.
3322 
3323 // Adjust cpools and vtables closure
3324 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3325 
3326   // This is a very busy routine. We don't want too much tracing
3327   // printed out.
3328   bool trace_name_printed = false;
3329   InstanceKlass *the_class = InstanceKlass::cast(_the_class_oop);
3330 
3331   // Very noisy: only enable this call if you are trying to determine
3332   // that a specific class gets found by this routine.
3333   // RC_TRACE macro has an embedded ResourceMark
3334   // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
3335   //   ("adjust check: name=%s", k->external_name()));
3336   // trace_name_printed = true;
3337 
3338   // If the class being redefined is java.lang.Object, we need to fix all
3339   // array class vtables also
3340   if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
3341     k->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3342 
3343   } else if (k->oop_is_instance()) {
3344     HandleMark hm(_thread);
3345     InstanceKlass *ik = InstanceKlass::cast(k);
3346 
3347     // HotSpot specific optimization! HotSpot does not currently
3348     // support delegation from the bootstrap class loader to a
3349     // user-defined class loader. This means that if the bootstrap
3350     // class loader is the initiating class loader, then it will also
3351     // be the defining class loader. This also means that classes
3352     // loaded by the bootstrap class loader cannot refer to classes
3353     // loaded by a user-defined class loader. Note: a user-defined
3354     // class loader can delegate to the bootstrap class loader.
3355     //
3356     // If the current class being redefined has a user-defined class
3357     // loader as its defining class loader, then we can skip all
3358     // classes loaded by the bootstrap class loader.
3359     bool is_user_defined =
3360            InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
3361     if (is_user_defined && ik->class_loader() == NULL) {
3362       return;
3363     }
3364 
3365     // Fix the vtable embedded in the_class and subclasses of the_class,
3366     // if one exists. We discard scratch_class and we don't keep an
3367     // InstanceKlass around to hold obsolete methods so we don't have
3368     // any other InstanceKlass embedded vtables to update. The vtable
3369     // holds the Method*s for virtual (but not final) methods.
3370     // Default methods, or concrete methods in interfaces are stored
3371     // in the vtable, so if an interface changes we need to check
3372     // adjust_method_entries() for every InstanceKlass, which will also
3373     // adjust the default method vtable indices.
3374     // We also need to adjust any default method entries that are
3375     // not yet in the vtable, because the vtable setup is in progress.
3376     // This must be done after we adjust the default_methods and
3377     // default_vtable_indices for methods already in the vtable.
3378     // If redefining Unsafe, walk all the vtables looking for entries.
3379     if (ik->vtable_length() > 0 && (_the_class_oop->is_interface()
3380         || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3381         || ik->is_subtype_of(_the_class_oop))) {
3382       // ik->vtable() creates a wrapper object; rm cleans it up
3383       ResourceMark rm(_thread);
3384 
3385       ik->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3386       ik->adjust_default_methods(the_class, &trace_name_printed);
3387     }
3388 
3389     // If the current class has an itable and we are either redefining an
3390     // interface or if the current class is a subclass of the_class, then
3391     // we potentially have to fix the itable. If we are redefining an
3392     // interface, then we have to call adjust_method_entries() for
3393     // every InstanceKlass that has an itable since there isn't a
3394     // subclass relationship between an interface and an InstanceKlass.
3395     // If redefining Unsafe, walk all the itables looking for entries.
3396     if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
3397         || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3398         || ik->is_subclass_of(_the_class_oop))) {
3399       // ik->itable() creates a wrapper object; rm cleans it up
3400       ResourceMark rm(_thread);
3401 
3402       ik->itable()->adjust_method_entries(the_class, &trace_name_printed);
3403     }
3404 
3405     // The constant pools in other classes (other_cp) can refer to
3406     // methods in the_class. We have to update method information in
3407     // other_cp's cache. If other_cp has a previous version, then we
3408     // have to repeat the process for each previous version. The
3409     // constant pool cache holds the Method*s for non-virtual
3410     // methods and for virtual, final methods.
3411     //
3412     // Special case: if the current class is the_class, then new_cp
3413     // has already been attached to the_class and old_cp has already
3414     // been added as a previous version. The new_cp doesn't have any
3415     // cached references to old methods so it doesn't need to be
3416     // updated. We can simply start with the previous version(s) in
3417     // that case.
3418     constantPoolHandle other_cp;
3419     ConstantPoolCache* cp_cache;
3420 
3421     if (ik != _the_class_oop) {
3422       // this klass' constant pool cache may need adjustment
3423       other_cp = constantPoolHandle(ik->constants());
3424       cp_cache = other_cp->cache();
3425       if (cp_cache != NULL) {
3426         cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3427       }
3428     }
3429 
3430     // the previous versions' constant pool caches may need adjustment
3431     for (InstanceKlass* pv_node = ik->previous_versions();
3432          pv_node != NULL;
3433          pv_node = pv_node->previous_versions()) {
3434       cp_cache = pv_node->constants()->cache();
3435       if (cp_cache != NULL) {
3436         cp_cache->adjust_method_entries(_matching_old_methods,
3437                                         _matching_new_methods,
3438                                         _matching_methods_length,
3439                                         &trace_name_printed);
3440       }
3441     }
3442   }
3443 }
3444 
3445 // Clean method data for this class
3446 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3447   if (k->oop_is_instance()) {
3448     InstanceKlass *ik = InstanceKlass::cast(k);
3449     // Clean MethodData of this class's methods so they don't refer to
3450     // old methods that are no longer running.
3451     Array<Method*>* methods = ik->methods();
3452     int num_methods = methods->length();
3453     for (int index = 0; index < num_methods; ++index) {
3454       if (methods->at(index)->method_data() != NULL) {
3455         methods->at(index)->method_data()->clean_weak_method_links();
3456       }
3457     }
3458   }
3459 }
3460 
3461 void VM_RedefineClasses::update_jmethod_ids() {
3462   for (int j = 0; j < _matching_methods_length; ++j) {
3463     Method* old_method = _matching_old_methods[j];
3464     jmethodID jmid = old_method->find_jmethod_id_or_null();
3465     if (jmid != NULL) {
3466       // There is a jmethodID, change it to point to the new method
3467       methodHandle new_method_h(_matching_new_methods[j]);
3468       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3469       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3470              "should be replaced");
3471     }
3472   }
3473 }
3474 
3475 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3476   int emcp_method_count = 0;
3477   int obsolete_count = 0;
3478   int old_index = 0;
3479   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3480     Method* old_method = _matching_old_methods[j];
3481     Method* new_method = _matching_new_methods[j];
3482     Method* old_array_method;
3483 
3484     // Maintain an old_index into the _old_methods array by skipping
3485     // deleted methods
3486     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3487       ++old_index;
3488     }
3489 
3490     if (MethodComparator::methods_EMCP(old_method, new_method)) {
3491       // The EMCP definition from JSR-163 requires the bytecodes to be
3492       // the same with the exception of constant pool indices which may
3493       // differ. However, the constants referred to by those indices
3494       // must be the same.
3495       //
3496       // We use methods_EMCP() for comparison since constant pool
3497       // merging can remove duplicate constant pool entries that were
3498       // present in the old method and removed from the rewritten new
3499       // method. A faster binary comparison function would consider the
3500       // old and new methods to be different when they are actually
3501       // EMCP.
3502       //
3503       // The old and new methods are EMCP and you would think that we
3504       // could get rid of one of them here and now and save some space.
3505       // However, the concept of EMCP only considers the bytecodes and
3506       // the constant pool entries in the comparison. Other things,
3507       // e.g., the line number table (LNT) or the local variable table
3508       // (LVT) don't count in the comparison. So the new (and EMCP)
3509       // method can have a new LNT that we need so we can't just
3510       // overwrite the new method with the old method.
3511       //
3512       // When this routine is called, we have already attached the new
3513       // methods to the_class so the old methods are effectively
3514       // overwritten. However, if an old method is still executing,
3515       // then the old method cannot be collected until sometime after
3516       // the old method call has returned. So the overwriting of old
3517       // methods by new methods will save us space except for those
3518       // (hopefully few) old methods that are still executing.
3519       //
3520       // A method refers to a ConstMethod* and this presents another
3521       // possible avenue to space savings. The ConstMethod* in the
3522       // new method contains possibly new attributes (LNT, LVT, etc).
3523       // At first glance, it seems possible to save space by replacing
3524       // the ConstMethod* in the old method with the ConstMethod*
3525       // from the new method. The old and new methods would share the
3526       // same ConstMethod* and we would save the space occupied by
3527       // the old ConstMethod*. However, the ConstMethod* contains
3528       // a back reference to the containing method. Sharing the
3529       // ConstMethod* between two methods could lead to confusion in
3530       // the code that uses the back reference. This would lead to
3531       // brittle code that could be broken in non-obvious ways now or
3532       // in the future.
3533       //
3534       // Another possibility is to copy the ConstMethod* from the new
3535       // method to the old method and then overwrite the new method with
3536       // the old method. Since the ConstMethod* contains the bytecodes
3537       // for the method embedded in the oop, this option would change
3538       // the bytecodes out from under any threads executing the old
3539       // method and make the thread's bcp invalid. Since EMCP requires
3540       // that the bytecodes be the same modulo constant pool indices, it
3541       // is straight forward to compute the correct new bcp in the new
3542       // ConstMethod* from the old bcp in the old ConstMethod*. The
3543       // time consuming part would be searching all the frames in all
3544       // of the threads to find all of the calls to the old method.
3545       //
3546       // It looks like we will have to live with the limited savings
3547       // that we get from effectively overwriting the old methods
3548       // when the new methods are attached to the_class.
3549 
3550       // Count number of methods that are EMCP.  The method will be marked
3551       // old but not obsolete if it is EMCP.
3552       emcp_method_count++;
3553 
3554       // An EMCP method is _not_ obsolete. An obsolete method has a
3555       // different jmethodID than the current method. An EMCP method
3556       // has the same jmethodID as the current method. Having the
3557       // same jmethodID for all EMCP versions of a method allows for
3558       // a consistent view of the EMCP methods regardless of which
3559       // EMCP method you happen to have in hand. For example, a
3560       // breakpoint set in one EMCP method will work for all EMCP
3561       // versions of the method including the current one.
3562     } else {
3563       // mark obsolete methods as such
3564       old_method->set_is_obsolete();
3565       obsolete_count++;
3566 
3567       // obsolete methods need a unique idnum so they become new entries in
3568       // the jmethodID cache in InstanceKlass
3569       assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3570       u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
3571       if (num != ConstMethod::UNSET_IDNUM) {
3572         old_method->set_method_idnum(num);
3573       }
3574 
3575       // With tracing we try not to "yack" too much. The position of
3576       // this trace assumes there are fewer obsolete methods than
3577       // EMCP methods.
3578       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
3579         old_method->name()->as_C_string(),
3580         old_method->signature()->as_C_string()));
3581     }
3582     old_method->set_is_old();
3583   }
3584   for (int i = 0; i < _deleted_methods_length; ++i) {
3585     Method* old_method = _deleted_methods[i];
3586 
3587     assert(!old_method->has_vtable_index(),
3588            "cannot delete methods with vtable entries");;
3589 
3590     // Mark all deleted methods as old, obsolete and deleted
3591     old_method->set_is_deleted();
3592     old_method->set_is_old();
3593     old_method->set_is_obsolete();
3594     ++obsolete_count;
3595     // With tracing we try not to "yack" too much. The position of
3596     // this trace assumes there are fewer obsolete methods than
3597     // EMCP methods.
3598     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
3599                           old_method->name()->as_C_string(),
3600                           old_method->signature()->as_C_string()));
3601   }
3602   assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3603     "sanity check");
3604   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count,
3605     obsolete_count));
3606   return emcp_method_count;
3607 }
3608 
3609 // This internal class transfers the native function registration from old methods
3610 // to new methods.  It is designed to handle both the simple case of unchanged
3611 // native methods and the complex cases of native method prefixes being added and/or
3612 // removed.
3613 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3614 //
3615 // This class is used after the new methods have been installed in "the_class".
3616 //
3617 // So, for example, the following must be handled.  Where 'm' is a method and
3618 // a number followed by an underscore is a prefix.
3619 //
3620 //                                      Old Name    New Name
3621 // Simple transfer to new method        m       ->  m
3622 // Add prefix                           m       ->  1_m
3623 // Remove prefix                        1_m     ->  m
3624 // Simultaneous add of prefixes         m       ->  3_2_1_m
3625 // Simultaneous removal of prefixes     3_2_1_m ->  m
3626 // Simultaneous add and remove          1_m     ->  2_m
3627 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
3628 //
3629 class TransferNativeFunctionRegistration {
3630  private:
3631   instanceKlassHandle the_class;
3632   int prefix_count;
3633   char** prefixes;
3634 
3635   // Recursively search the binary tree of possibly prefixed method names.
3636   // Iteration could be used if all agents were well behaved. Full tree walk is
3637   // more resilent to agents not cleaning up intermediate methods.
3638   // Branch at each depth in the binary tree is:
3639   //    (1) without the prefix.
3640   //    (2) with the prefix.
3641   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3642   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3643                                      Symbol* signature) {
3644     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3645     if (name_symbol != NULL) {
3646       Method* method = the_class()->lookup_method(name_symbol, signature);
3647       if (method != NULL) {
3648         // Even if prefixed, intermediate methods must exist.
3649         if (method->is_native()) {
3650           // Wahoo, we found a (possibly prefixed) version of the method, return it.
3651           return method;
3652         }
3653         if (depth < prefix_count) {
3654           // Try applying further prefixes (other than this one).
3655           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3656           if (method != NULL) {
3657             return method; // found
3658           }
3659 
3660           // Try adding this prefix to the method name and see if it matches
3661           // another method name.
3662           char* prefix = prefixes[depth];
3663           size_t prefix_len = strlen(prefix);
3664           size_t trial_len = name_len + prefix_len;
3665           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3666           strcpy(trial_name_str, prefix);
3667           strcat(trial_name_str, name_str);
3668           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3669                                             signature);
3670           if (method != NULL) {
3671             // If found along this branch, it was prefixed, mark as such
3672             method->set_is_prefixed_native();
3673             return method; // found
3674           }
3675         }
3676       }
3677     }
3678     return NULL;  // This whole branch bore nothing
3679   }
3680 
3681   // Return the method name with old prefixes stripped away.
3682   char* method_name_without_prefixes(Method* method) {
3683     Symbol* name = method->name();
3684     char* name_str = name->as_utf8();
3685 
3686     // Old prefixing may be defunct, strip prefixes, if any.
3687     for (int i = prefix_count-1; i >= 0; i--) {
3688       char* prefix = prefixes[i];
3689       size_t prefix_len = strlen(prefix);
3690       if (strncmp(prefix, name_str, prefix_len) == 0) {
3691         name_str += prefix_len;
3692       }
3693     }
3694     return name_str;
3695   }
3696 
3697   // Strip any prefixes off the old native method, then try to find a
3698   // (possibly prefixed) new native that matches it.
3699   Method* strip_and_search_for_new_native(Method* method) {
3700     ResourceMark rm;
3701     char* name_str = method_name_without_prefixes(method);
3702     return search_prefix_name_space(0, name_str, strlen(name_str),
3703                                     method->signature());
3704   }
3705 
3706  public:
3707 
3708   // Construct a native method transfer processor for this class.
3709   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
3710     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3711 
3712     the_class = _the_class;
3713     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3714   }
3715 
3716   // Attempt to transfer any of the old or deleted methods that are native
3717   void transfer_registrations(Method** old_methods, int methods_length) {
3718     for (int j = 0; j < methods_length; j++) {
3719       Method* old_method = old_methods[j];
3720 
3721       if (old_method->is_native() && old_method->has_native_function()) {
3722         Method* new_method = strip_and_search_for_new_native(old_method);
3723         if (new_method != NULL) {
3724           // Actually set the native function in the new method.
3725           // Redefine does not send events (except CFLH), certainly not this
3726           // behind the scenes re-registration.
3727           new_method->set_native_function(old_method->native_function(),
3728                               !Method::native_bind_event_is_interesting);
3729         }
3730       }
3731     }
3732   }
3733 };
3734 
3735 // Don't lose the association between a native method and its JNI function.
3736 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
3737   TransferNativeFunctionRegistration transfer(the_class);
3738   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3739   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3740 }
3741 
3742 // Deoptimize all compiled code that depends on this class.
3743 //
3744 // If the can_redefine_classes capability is obtained in the onload
3745 // phase then the compiler has recorded all dependencies from startup.
3746 // In that case we need only deoptimize and throw away all compiled code
3747 // that depends on the class.
3748 //
3749 // If can_redefine_classes is obtained sometime after the onload
3750 // phase then the dependency information may be incomplete. In that case
3751 // the first call to RedefineClasses causes all compiled code to be
3752 // thrown away. As can_redefine_classes has been obtained then
3753 // all future compilations will record dependencies so second and
3754 // subsequent calls to RedefineClasses need only throw away code
3755 // that depends on the class.
3756 //
3757 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
3758   assert_locked_or_safepoint(Compile_lock);
3759 
3760   // All dependencies have been recorded from startup or this is a second or
3761   // subsequent use of RedefineClasses
3762   if (JvmtiExport::all_dependencies_are_recorded()) {
3763     CodeCache::flush_evol_dependents_on(k_h);
3764   } else {
3765     CodeCache::mark_all_nmethods_for_deoptimization();
3766 
3767     ResourceMark rm(THREAD);
3768     DeoptimizationMarker dm;
3769 
3770     // Deoptimize all activations depending on marked nmethods
3771     Deoptimization::deoptimize_dependents();
3772 
3773     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
3774     CodeCache::make_marked_nmethods_not_entrant();
3775 
3776     // From now on we know that the dependency information is complete
3777     JvmtiExport::set_all_dependencies_are_recorded(true);
3778   }
3779 }
3780 
3781 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3782   Method* old_method;
3783   Method* new_method;
3784 
3785   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3786   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3787   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3788   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3789 
3790   _matching_methods_length = 0;
3791   _deleted_methods_length  = 0;
3792   _added_methods_length    = 0;
3793 
3794   int nj = 0;
3795   int oj = 0;
3796   while (true) {
3797     if (oj >= _old_methods->length()) {
3798       if (nj >= _new_methods->length()) {
3799         break; // we've looked at everything, done
3800       }
3801       // New method at the end
3802       new_method = _new_methods->at(nj);
3803       _added_methods[_added_methods_length++] = new_method;
3804       ++nj;
3805     } else if (nj >= _new_methods->length()) {
3806       // Old method, at the end, is deleted
3807       old_method = _old_methods->at(oj);
3808       _deleted_methods[_deleted_methods_length++] = old_method;
3809       ++oj;
3810     } else {
3811       old_method = _old_methods->at(oj);
3812       new_method = _new_methods->at(nj);
3813       if (old_method->name()->equals(new_method->name())) {
3814         if (old_method->signature()->equals(new_method->signature())) {
3815           _matching_old_methods[_matching_methods_length  ] = old_method;
3816           _matching_new_methods[_matching_methods_length++] = new_method;
3817           ++nj;
3818           ++oj;
3819         } else {
3820           // added overloaded have already been moved to the end,
3821           // so this is a deleted overloaded method
3822           _deleted_methods[_deleted_methods_length++] = old_method;
3823           ++oj;
3824         }
3825       } else { // names don't match
3826         if (old_method->name()->fast_compare(new_method->name()) > 0) {
3827           // new method
3828           _added_methods[_added_methods_length++] = new_method;
3829           ++nj;
3830         } else {
3831           // deleted method
3832           _deleted_methods[_deleted_methods_length++] = old_method;
3833           ++oj;
3834         }
3835       }
3836     }
3837   }
3838   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3839   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3840 }
3841 
3842 
3843 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
3844                                           instanceKlassHandle scratch_class) {
3845   // Swap annotation fields values
3846   Annotations* old_annotations = the_class->annotations();
3847   the_class->set_annotations(scratch_class->annotations());
3848   scratch_class->set_annotations(old_annotations);
3849 }
3850 
3851 
3852 // Install the redefinition of a class:
3853 //    - house keeping (flushing breakpoints and caches, deoptimizing
3854 //      dependent compiled code)
3855 //    - replacing parts in the_class with parts from scratch_class
3856 //    - adding a weak reference to track the obsolete but interesting
3857 //      parts of the_class
3858 //    - adjusting constant pool caches and vtables in other classes
3859 //      that refer to methods in the_class. These adjustments use the
3860 //      ClassLoaderDataGraph::classes_do() facility which only allows
3861 //      a helper method to be specified. The interesting parameters
3862 //      that we would like to pass to the helper method are saved in
3863 //      static global fields in the VM operation.
3864 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3865        Klass* scratch_class_oop, TRAPS) {
3866 
3867   HandleMark hm(THREAD);   // make sure handles from this call are freed
3868   RC_TIMER_START(_timer_rsc_phase1);
3869 
3870   instanceKlassHandle scratch_class(scratch_class_oop);
3871 
3872   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3873   Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
3874   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3875 
3876   // Remove all breakpoints in methods of this class
3877   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3878   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3879 
3880   // Deoptimize all compiled code that depends on this class
3881   flush_dependent_code(the_class, THREAD);
3882 
3883   _old_methods = the_class->methods();
3884   _new_methods = scratch_class->methods();
3885   _the_class_oop = the_class_oop;
3886   compute_added_deleted_matching_methods();
3887   update_jmethod_ids();
3888 
3889   // Attach new constant pool to the original klass. The original
3890   // klass still refers to the old constant pool (for now).
3891   scratch_class->constants()->set_pool_holder(the_class());
3892 
3893 #if 0
3894   // In theory, with constant pool merging in place we should be able
3895   // to save space by using the new, merged constant pool in place of
3896   // the old constant pool(s). By "pool(s)" I mean the constant pool in
3897   // the klass version we are replacing now and any constant pool(s) in
3898   // previous versions of klass. Nice theory, doesn't work in practice.
3899   // When this code is enabled, even simple programs throw NullPointer
3900   // exceptions. I'm guessing that this is caused by some constant pool
3901   // cache difference between the new, merged constant pool and the
3902   // constant pool that was just being used by the klass. I'm keeping
3903   // this code around to archive the idea, but the code has to remain
3904   // disabled for now.
3905 
3906   // Attach each old method to the new constant pool. This can be
3907   // done here since we are past the bytecode verification and
3908   // constant pool optimization phases.
3909   for (int i = _old_methods->length() - 1; i >= 0; i--) {
3910     Method* method = _old_methods->at(i);
3911     method->set_constants(scratch_class->constants());
3912   }
3913 
3914   {
3915     // walk all previous versions of the klass
3916     InstanceKlass *ik = (InstanceKlass *)the_class();
3917     PreviousVersionWalker pvw(ik);
3918     instanceKlassHandle ikh;
3919     do {
3920       ikh = pvw.next_previous_version();
3921       if (!ikh.is_null()) {
3922         ik = ikh();
3923 
3924         // attach previous version of klass to the new constant pool
3925         ik->set_constants(scratch_class->constants());
3926 
3927         // Attach each method in the previous version of klass to the
3928         // new constant pool
3929         Array<Method*>* prev_methods = ik->methods();
3930         for (int i = prev_methods->length() - 1; i >= 0; i--) {
3931           Method* method = prev_methods->at(i);
3932           method->set_constants(scratch_class->constants());
3933         }
3934       }
3935     } while (!ikh.is_null());
3936   }
3937 #endif
3938 
3939   // Replace methods and constantpool
3940   the_class->set_methods(_new_methods);
3941   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
3942                                           // and to be able to undo operation easily.
3943 
3944   ConstantPool* old_constants = the_class->constants();
3945   the_class->set_constants(scratch_class->constants());
3946   scratch_class->set_constants(old_constants);  // See the previous comment.
3947 #if 0
3948   // We are swapping the guts of "the new class" with the guts of "the
3949   // class". Since the old constant pool has just been attached to "the
3950   // new class", it seems logical to set the pool holder in the old
3951   // constant pool also. However, doing this will change the observable
3952   // class hierarchy for any old methods that are still executing. A
3953   // method can query the identity of its "holder" and this query uses
3954   // the method's constant pool link to find the holder. The change in
3955   // holding class from "the class" to "the new class" can confuse
3956   // things.
3957   //
3958   // Setting the old constant pool's holder will also cause
3959   // verification done during vtable initialization below to fail.
3960   // During vtable initialization, the vtable's class is verified to be
3961   // a subtype of the method's holder. The vtable's class is "the
3962   // class" and the method's holder is gotten from the constant pool
3963   // link in the method itself. For "the class"'s directly implemented
3964   // methods, the method holder is "the class" itself (as gotten from
3965   // the new constant pool). The check works fine in this case. The
3966   // check also works fine for methods inherited from super classes.
3967   //
3968   // Miranda methods are a little more complicated. A miranda method is
3969   // provided by an interface when the class implementing the interface
3970   // does not provide its own method.  These interfaces are implemented
3971   // internally as an InstanceKlass. These special instanceKlasses
3972   // share the constant pool of the class that "implements" the
3973   // interface. By sharing the constant pool, the method holder of a
3974   // miranda method is the class that "implements" the interface. In a
3975   // non-redefine situation, the subtype check works fine. However, if
3976   // the old constant pool's pool holder is modified, then the check
3977   // fails because there is no class hierarchy relationship between the
3978   // vtable's class and "the new class".
3979 
3980   old_constants->set_pool_holder(scratch_class());
3981 #endif
3982 
3983   // track number of methods that are EMCP for add_previous_version() call below
3984   int emcp_method_count = check_methods_and_mark_as_obsolete();
3985   transfer_old_native_function_registrations(the_class);
3986 
3987   // The class file bytes from before any retransformable agents mucked
3988   // with them was cached on the scratch class, move to the_class.
3989   // Note: we still want to do this if nothing needed caching since it
3990   // should get cleared in the_class too.
3991   if (the_class->get_cached_class_file_bytes() == 0) {
3992     // the_class doesn't have a cache yet so copy it
3993     the_class->set_cached_class_file(scratch_class->get_cached_class_file());
3994   }
3995   else if (scratch_class->get_cached_class_file_bytes() !=
3996            the_class->get_cached_class_file_bytes()) {
3997     // The same class can be present twice in the scratch classes list or there
3998     // are multiple concurrent RetransformClasses calls on different threads.
3999     // In such cases we have to deallocate scratch_class cached_class_file_bytes.
4000     os::free(scratch_class->get_cached_class_file_bytes());
4001   }
4002 
4003   // NULL out in scratch class to not delete twice.  The class to be redefined
4004   // always owns these bytes.
4005   scratch_class->set_cached_class_file(NULL);
4006 
4007   // Replace inner_classes
4008   Array<u2>* old_inner_classes = the_class->inner_classes();
4009   the_class->set_inner_classes(scratch_class->inner_classes());
4010   scratch_class->set_inner_classes(old_inner_classes);
4011 
4012   // Initialize the vtable and interface table after
4013   // methods have been rewritten
4014   {
4015     ResourceMark rm(THREAD);
4016     // no exception should happen here since we explicitly
4017     // do not check loader constraints.
4018     // compare_and_normalize_class_versions has already checked:
4019     //  - classloaders unchanged, signatures unchanged
4020     //  - all instanceKlasses for redefined classes reused & contents updated
4021     the_class->vtable()->initialize_vtable(false, THREAD);
4022     the_class->itable()->initialize_itable(false, THREAD);
4023     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4024   }
4025 
4026   // Leave arrays of jmethodIDs and itable index cache unchanged
4027 
4028   // Copy the "source file name" attribute from new class version
4029   the_class->set_source_file_name_index(
4030     scratch_class->source_file_name_index());
4031 
4032   // Copy the "source debug extension" attribute from new class version
4033   the_class->set_source_debug_extension(
4034     scratch_class->source_debug_extension(),
4035     scratch_class->source_debug_extension() == NULL ? 0 :
4036     (int)strlen(scratch_class->source_debug_extension()));
4037 
4038   // Use of javac -g could be different in the old and the new
4039   if (scratch_class->access_flags().has_localvariable_table() !=
4040       the_class->access_flags().has_localvariable_table()) {
4041 
4042     AccessFlags flags = the_class->access_flags();
4043     if (scratch_class->access_flags().has_localvariable_table()) {
4044       flags.set_has_localvariable_table();
4045     } else {
4046       flags.clear_has_localvariable_table();
4047     }
4048     the_class->set_access_flags(flags);
4049   }
4050 
4051   swap_annotations(the_class, scratch_class);
4052 
4053   // Replace minor version number of class file
4054   u2 old_minor_version = the_class->minor_version();
4055   the_class->set_minor_version(scratch_class->minor_version());
4056   scratch_class->set_minor_version(old_minor_version);
4057 
4058   // Replace major version number of class file
4059   u2 old_major_version = the_class->major_version();
4060   the_class->set_major_version(scratch_class->major_version());
4061   scratch_class->set_major_version(old_major_version);
4062 
4063   // Replace CP indexes for class and name+type of enclosing method
4064   u2 old_class_idx  = the_class->enclosing_method_class_index();
4065   u2 old_method_idx = the_class->enclosing_method_method_index();
4066   the_class->set_enclosing_method_indices(
4067     scratch_class->enclosing_method_class_index(),
4068     scratch_class->enclosing_method_method_index());
4069   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4070 
4071   the_class->set_has_been_redefined();
4072 
4073   // keep track of previous versions of this class
4074   the_class->add_previous_version(scratch_class, emcp_method_count);
4075 
4076   RC_TIMER_STOP(_timer_rsc_phase1);
4077   RC_TIMER_START(_timer_rsc_phase2);
4078 
4079   // Adjust constantpool caches and vtables for all classes
4080   // that reference methods of the evolved class.
4081   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4082   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4083 
4084   // JSR-292 support
4085   MemberNameTable* mnt = the_class->member_names();
4086   if (mnt != NULL) {
4087     bool trace_name_printed = false;
4088     mnt->adjust_method_entries(_matching_old_methods,
4089                                _matching_new_methods,
4090                                _matching_methods_length,
4091                                &trace_name_printed);
4092   }
4093 
4094   // Fix Resolution Error table also to remove old constant pools
4095   SystemDictionary::delete_resolution_error(old_constants);
4096 
4097   if (the_class->oop_map_cache() != NULL) {
4098     // Flush references to any obsolete methods from the oop map cache
4099     // so that obsolete methods are not pinned.
4100     the_class->oop_map_cache()->flush_obsolete_entries();
4101   }
4102 
4103   // increment the classRedefinedCount field in the_class and in any
4104   // direct and indirect subclasses of the_class
4105   increment_class_counter((InstanceKlass *)the_class(), THREAD);
4106 
4107   // RC_TRACE macro has an embedded ResourceMark
4108   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
4109     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4110     the_class->external_name(),
4111     java_lang_Class::classRedefinedCount(the_class_mirror),
4112     os::available_memory() >> 10));
4113 
4114   RC_TIMER_STOP(_timer_rsc_phase2);
4115 } // end redefine_single_class()
4116 
4117 
4118 // Increment the classRedefinedCount field in the specific InstanceKlass
4119 // and in all direct and indirect subclasses.
4120 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4121   oop class_mirror = ik->java_mirror();
4122   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4123   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4124   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4125 
4126   if (class_oop != _the_class_oop) {
4127     // _the_class_oop count is printed at end of redefine_single_class()
4128     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
4129       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
4130   }
4131 
4132   for (Klass *subk = ik->subklass(); subk != NULL;
4133        subk = subk->next_sibling()) {
4134     if (subk->oop_is_instance()) {
4135       // Only update instanceKlasses
4136       InstanceKlass *subik = (InstanceKlass*)subk;
4137       // recursively do subclasses of the current subclass
4138       increment_class_counter(subik, THREAD);
4139     }
4140   }
4141 }
4142 
4143 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4144   bool no_old_methods = true;  // be optimistic
4145 
4146   // Both array and instance classes have vtables.
4147   // a vtable should never contain old or obsolete methods
4148   ResourceMark rm(_thread);
4149   if (k->vtable_length() > 0 &&
4150       !k->vtable()->check_no_old_or_obsolete_entries()) {
4151     if (RC_TRACE_ENABLED(0x00004000)) {
4152       RC_TRACE_WITH_THREAD(0x00004000, _thread,
4153         ("klassVtable::check_no_old_or_obsolete_entries failure"
4154          " -- OLD or OBSOLETE method found -- class: %s",
4155          k->signature_name()));
4156       k->vtable()->dump_vtable();
4157     }
4158     no_old_methods = false;
4159   }
4160 
4161   if (k->oop_is_instance()) {
4162     HandleMark hm(_thread);
4163     InstanceKlass *ik = InstanceKlass::cast(k);
4164 
4165     // an itable should never contain old or obsolete methods
4166     if (ik->itable_length() > 0 &&
4167         !ik->itable()->check_no_old_or_obsolete_entries()) {
4168       if (RC_TRACE_ENABLED(0x00004000)) {
4169         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4170           ("klassItable::check_no_old_or_obsolete_entries failure"
4171            " -- OLD or OBSOLETE method found -- class: %s",
4172            ik->signature_name()));
4173         ik->itable()->dump_itable();
4174       }
4175       no_old_methods = false;
4176     }
4177 
4178     // the constant pool cache should never contain non-deleted old or obsolete methods
4179     if (ik->constants() != NULL &&
4180         ik->constants()->cache() != NULL &&
4181         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4182       if (RC_TRACE_ENABLED(0x00004000)) {
4183         RC_TRACE_WITH_THREAD(0x00004000, _thread,
4184           ("cp-cache::check_no_old_or_obsolete_entries failure"
4185            " -- OLD or OBSOLETE method found -- class: %s",
4186            ik->signature_name()));
4187         ik->constants()->cache()->dump_cache();
4188       }
4189       no_old_methods = false;
4190     }
4191   }
4192 
4193   // print and fail guarantee if old methods are found.
4194   if (!no_old_methods) {
4195     if (RC_TRACE_ENABLED(0x00004000)) {
4196       dump_methods();
4197     } else {
4198       tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
4199         "to see more info about the following guarantee() failure.");
4200     }
4201     guarantee(false, "OLD and/or OBSOLETE method(s) found");
4202   }
4203 }
4204 
4205 
4206 void VM_RedefineClasses::dump_methods() {
4207   int j;
4208   RC_TRACE(0x00004000, ("_old_methods --"));
4209   for (j = 0; j < _old_methods->length(); ++j) {
4210     Method* m = _old_methods->at(j);
4211     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4212     m->access_flags().print_on(tty);
4213     tty->print(" --  ");
4214     m->print_name(tty);
4215     tty->cr();
4216   }
4217   RC_TRACE(0x00004000, ("_new_methods --"));
4218   for (j = 0; j < _new_methods->length(); ++j) {
4219     Method* m = _new_methods->at(j);
4220     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4221     m->access_flags().print_on(tty);
4222     tty->print(" --  ");
4223     m->print_name(tty);
4224     tty->cr();
4225   }
4226   RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
4227   for (j = 0; j < _matching_methods_length; ++j) {
4228     Method* m = _matching_old_methods[j];
4229     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4230     m->access_flags().print_on(tty);
4231     tty->print(" --  ");
4232     m->print_name(tty);
4233     tty->cr();
4234     m = _matching_new_methods[j];
4235     RC_TRACE_NO_CR(0x00004000, ("      (%5d)  ", m->vtable_index()));
4236     m->access_flags().print_on(tty);
4237     tty->cr();
4238   }
4239   RC_TRACE(0x00004000, ("_deleted_methods --"));
4240   for (j = 0; j < _deleted_methods_length; ++j) {
4241     Method* m = _deleted_methods[j];
4242     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4243     m->access_flags().print_on(tty);
4244     tty->print(" --  ");
4245     m->print_name(tty);
4246     tty->cr();
4247   }
4248   RC_TRACE(0x00004000, ("_added_methods --"));
4249   for (j = 0; j < _added_methods_length; ++j) {
4250     Method* m = _added_methods[j];
4251     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
4252     m->access_flags().print_on(tty);
4253     tty->print(" --  ");
4254     m->print_name(tty);
4255     tty->cr();
4256   }
4257 }