1 /*
   2  * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/resolutionErrors.hpp"
  27 #include "interpreter/bytecodeStream.hpp"
  28 #include "interpreter/bytecodes.hpp"
  29 #include "interpreter/interpreter.hpp"
  30 #include "interpreter/rewriter.hpp"
  31 #include "logging/log.hpp"
  32 #include "memory/metadataFactory.hpp"
  33 #include "memory/metaspaceClosure.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "memory/universe.inline.hpp"
  36 #include "oops/access.inline.hpp"
  37 #include "oops/cpCache.hpp"
  38 #include "oops/objArrayOop.inline.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "prims/methodHandles.hpp"
  41 #include "runtime/atomic.hpp"
  42 #include "runtime/handles.inline.hpp"
  43 #include "runtime/orderAccess.inline.hpp"
  44 #include "utilities/macros.hpp"
  45 
  46 // Implementation of ConstantPoolCacheEntry
  47 
  48 void ConstantPoolCacheEntry::initialize_entry(int index) {
  49   assert(0 < index && index < 0x10000, "sanity check");
  50   _indices = index;
  51   _f1 = NULL;
  52   _f2 = _flags = 0;
  53   assert(constant_pool_index() == index, "");
  54 }
  55 
  56 void ConstantPoolCacheEntry::verify_just_initialized(bool f2_used) {
  57   assert((_indices & (~cp_index_mask)) == 0, "sanity");
  58   assert(_f1 == NULL, "sanity");
  59   assert(_flags == 0, "sanity");
  60   if (!f2_used) {
  61     assert(_f2 == 0, "sanity");
  62   }
  63 }
  64 
  65 void ConstantPoolCacheEntry::reinitialize(bool f2_used) {
  66   _indices &= cp_index_mask;
  67   _f1 = NULL;
  68   _flags = 0;
  69   if (!f2_used) {
  70     _f2 = 0;
  71   }
  72 }
  73 
  74 int ConstantPoolCacheEntry::make_flags(TosState state,
  75                                        int option_bits,
  76                                        int field_index_or_method_params) {
  77   assert(state < number_of_states, "Invalid state in make_flags");
  78   int f = ((int)state << tos_state_shift) | option_bits | field_index_or_method_params;
  79   // Preserve existing flag bit values
  80   // The low bits are a field offset, or else the method parameter size.
  81 #ifdef ASSERT
  82   TosState old_state = flag_state();
  83   assert(old_state == (TosState)0 || old_state == state,
  84          "inconsistent cpCache flags state");
  85 #endif
  86   return (_flags | f) ;
  87 }
  88 
  89 void ConstantPoolCacheEntry::set_bytecode_1(Bytecodes::Code code) {
  90 #ifdef ASSERT
  91   // Read once.
  92   volatile Bytecodes::Code c = bytecode_1();
  93   assert(c == 0 || c == code || code == 0, "update must be consistent");
  94 #endif
  95   // Need to flush pending stores here before bytecode is written.
  96   OrderAccess::release_store(&_indices, _indices | ((u_char)code << bytecode_1_shift));
  97 }
  98 
  99 void ConstantPoolCacheEntry::set_bytecode_2(Bytecodes::Code code) {
 100 #ifdef ASSERT
 101   // Read once.
 102   volatile Bytecodes::Code c = bytecode_2();
 103   assert(c == 0 || c == code || code == 0, "update must be consistent");
 104 #endif
 105   // Need to flush pending stores here before bytecode is written.
 106   OrderAccess::release_store(&_indices, _indices | ((u_char)code << bytecode_2_shift));
 107 }
 108 
 109 // Sets f1, ordering with previous writes.
 110 void ConstantPoolCacheEntry::release_set_f1(Metadata* f1) {
 111   assert(f1 != NULL, "");
 112   OrderAccess::release_store(&_f1, f1);
 113 }
 114 
 115 void ConstantPoolCacheEntry::set_indy_resolution_failed() {
 116   OrderAccess::release_store(&_flags, _flags | (1 << indy_resolution_failed_shift));
 117 }
 118 
 119 // Note that concurrent update of both bytecodes can leave one of them
 120 // reset to zero.  This is harmless; the interpreter will simply re-resolve
 121 // the damaged entry.  More seriously, the memory synchronization is needed
 122 // to flush other fields (f1, f2) completely to memory before the bytecodes
 123 // are updated, lest other processors see a non-zero bytecode but zero f1/f2.
 124 void ConstantPoolCacheEntry::set_field(Bytecodes::Code get_code,
 125                                        Bytecodes::Code put_code,
 126                                        Klass* field_holder,
 127                                        int field_index,
 128                                        int field_offset,
 129                                        TosState field_type,
 130                                        bool is_final,
 131                                        bool is_volatile,
 132                                        Klass* root_klass) {
 133   set_f1(field_holder);
 134   set_f2(field_offset);
 135   assert((field_index & field_index_mask) == field_index,
 136          "field index does not fit in low flag bits");
 137   set_field_flags(field_type,
 138                   ((is_volatile ? 1 : 0) << is_volatile_shift) |
 139                   ((is_final    ? 1 : 0) << is_final_shift),
 140                   field_index);
 141   set_bytecode_1(get_code);
 142   set_bytecode_2(put_code);
 143   NOT_PRODUCT(verify(tty));
 144 }
 145 
 146 void ConstantPoolCacheEntry::set_parameter_size(int value) {
 147   // This routine is called only in corner cases where the CPCE is not yet initialized.
 148   // See AbstractInterpreter::deopt_continue_after_entry.
 149   assert(_flags == 0 || parameter_size() == 0 || parameter_size() == value,
 150          "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
 151   // Setting the parameter size by itself is only safe if the
 152   // current value of _flags is 0, otherwise another thread may have
 153   // updated it and we don't want to overwrite that value.  Don't
 154   // bother trying to update it once it's nonzero but always make
 155   // sure that the final parameter size agrees with what was passed.
 156   if (_flags == 0) {
 157     intx newflags = (value & parameter_size_mask);
 158     Atomic::cmpxchg(newflags, &_flags, (intx)0);
 159   }
 160   guarantee(parameter_size() == value,
 161             "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
 162 }
 163 
 164 void ConstantPoolCacheEntry::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
 165                                                        const methodHandle& method,
 166                                                        int vtable_index,
 167                                                        bool sender_is_interface) {
 168   bool is_vtable_call = (vtable_index >= 0);  // FIXME: split this method on this boolean
 169   assert(method->interpreter_entry() != NULL, "should have been set at this point");
 170   assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");
 171 
 172   int byte_no = -1;
 173   bool change_to_virtual = false;
 174 
 175   switch (invoke_code) {
 176     case Bytecodes::_invokeinterface:
 177       // We get here from InterpreterRuntime::resolve_invoke when an invokeinterface
 178       // instruction somehow links to a non-interface method (in Object).
 179       // In that case, the method has no itable index and must be invoked as a virtual.
 180       // Set a flag to keep track of this corner case.
 181       assert(method->is_public(), "Calling non-public method in Object with invokeinterface");
 182       change_to_virtual = true;
 183 
 184       // ...and fall through as if we were handling invokevirtual:
 185     case Bytecodes::_invokevirtual:
 186       {
 187         if (!is_vtable_call) {
 188           assert(method->can_be_statically_bound(), "");
 189           // set_f2_as_vfinal_method checks if is_vfinal flag is true.
 190           set_method_flags(as_TosState(method->result_type()),
 191                            (                             1      << is_vfinal_shift) |
 192                            ((method->is_final_method() ? 1 : 0) << is_final_shift)  |
 193                            ((change_to_virtual         ? 1 : 0) << is_forced_virtual_shift),
 194                            method()->size_of_parameters());
 195           set_f2_as_vfinal_method(method());
 196         } else {
 197           assert(!method->can_be_statically_bound(), "");
 198           assert(vtable_index >= 0, "valid index");
 199           assert(!method->is_final_method(), "sanity");
 200           set_method_flags(as_TosState(method->result_type()),
 201                            ((change_to_virtual ? 1 : 0) << is_forced_virtual_shift),
 202                            method()->size_of_parameters());
 203           set_f2(vtable_index);
 204         }
 205         byte_no = 2;
 206         break;
 207       }
 208 
 209     case Bytecodes::_invokespecial:
 210     case Bytecodes::_invokestatic:
 211       assert(!is_vtable_call, "");
 212       // Note:  Read and preserve the value of the is_vfinal flag on any
 213       // invokevirtual bytecode shared with this constant pool cache entry.
 214       // It is cheap and safe to consult is_vfinal() at all times.
 215       // Once is_vfinal is set, it must stay that way, lest we get a dangling oop.
 216       set_method_flags(as_TosState(method->result_type()),
 217                        ((is_vfinal()               ? 1 : 0) << is_vfinal_shift) |
 218                        ((method->is_final_method() ? 1 : 0) << is_final_shift),
 219                        method()->size_of_parameters());
 220       set_f1(method());
 221       byte_no = 1;
 222       break;
 223     default:
 224       ShouldNotReachHere();
 225       break;
 226   }
 227 
 228   // Note:  byte_no also appears in TemplateTable::resolve.
 229   if (byte_no == 1) {
 230     assert(invoke_code != Bytecodes::_invokevirtual &&
 231            invoke_code != Bytecodes::_invokeinterface, "");
 232     // Don't mark invokespecial to method as resolved if sender is an interface.  The receiver
 233     // has to be checked that it is a subclass of the current class every time this bytecode
 234     // is executed.
 235     if (invoke_code != Bytecodes::_invokespecial || !sender_is_interface ||
 236         method->name() == vmSymbols::object_initializer_name()) {
 237     set_bytecode_1(invoke_code);
 238     }
 239   } else if (byte_no == 2)  {
 240     if (change_to_virtual) {
 241       assert(invoke_code == Bytecodes::_invokeinterface, "");
 242       // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
 243       //
 244       // Workaround for the case where we encounter an invokeinterface, but we
 245       // should really have an _invokevirtual since the resolved method is a
 246       // virtual method in java.lang.Object. This is a corner case in the spec
 247       // but is presumably legal. javac does not generate this code.
 248       //
 249       // We set bytecode_1() to _invokeinterface, because that is the
 250       // bytecode # used by the interpreter to see if it is resolved.
 251       // We set bytecode_2() to _invokevirtual.
 252       // See also interpreterRuntime.cpp. (8/25/2000)
 253       // Only set resolved for the invokeinterface case if method is public.
 254       // Otherwise, the method needs to be reresolved with caller for each
 255       // interface call.
 256       if (method->is_public()) set_bytecode_1(invoke_code);
 257     } else {
 258       assert(invoke_code == Bytecodes::_invokevirtual, "");
 259     }
 260     // set up for invokevirtual, even if linking for invokeinterface also:
 261     set_bytecode_2(Bytecodes::_invokevirtual);
 262   } else {
 263     ShouldNotReachHere();
 264   }
 265   NOT_PRODUCT(verify(tty));
 266 }
 267 
 268 void ConstantPoolCacheEntry::set_direct_call(Bytecodes::Code invoke_code, const methodHandle& method,
 269                                              bool sender_is_interface) {
 270   int index = Method::nonvirtual_vtable_index;
 271   // index < 0; FIXME: inline and customize set_direct_or_vtable_call
 272   set_direct_or_vtable_call(invoke_code, method, index, sender_is_interface);
 273 }
 274 
 275 void ConstantPoolCacheEntry::set_vtable_call(Bytecodes::Code invoke_code, const methodHandle& method, int index) {
 276   // either the method is a miranda or its holder should accept the given index
 277   assert(method->method_holder()->is_interface() || method->method_holder()->verify_vtable_index(index), "");
 278   // index >= 0; FIXME: inline and customize set_direct_or_vtable_call
 279   set_direct_or_vtable_call(invoke_code, method, index, false);
 280 }
 281 
 282 void ConstantPoolCacheEntry::set_itable_call(Bytecodes::Code invoke_code, const methodHandle& method, int index) {
 283   assert(method->method_holder()->verify_itable_index(index), "");
 284   assert(invoke_code == Bytecodes::_invokeinterface, "");
 285   InstanceKlass* interf = method->method_holder();
 286   assert(interf->is_interface(), "must be an interface");
 287   assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
 288   set_f1(interf);
 289   set_f2(index);
 290   set_method_flags(as_TosState(method->result_type()),
 291                    0,  // no option bits
 292                    method()->size_of_parameters());
 293   set_bytecode_1(Bytecodes::_invokeinterface);
 294 }
 295 
 296 
 297 void ConstantPoolCacheEntry::set_method_handle(const constantPoolHandle& cpool, const CallInfo &call_info) {
 298   set_method_handle_common(cpool, Bytecodes::_invokehandle, call_info);
 299 }
 300 
 301 void ConstantPoolCacheEntry::set_dynamic_call(const constantPoolHandle& cpool, const CallInfo &call_info) {
 302   set_method_handle_common(cpool, Bytecodes::_invokedynamic, call_info);
 303 }
 304 
 305 void ConstantPoolCacheEntry::set_method_handle_common(const constantPoolHandle& cpool,
 306                                                       Bytecodes::Code invoke_code,
 307                                                       const CallInfo &call_info) {
 308   // NOTE: This CPCE can be the subject of data races.
 309   // There are three words to update: flags, refs[f2], f1 (in that order).
 310   // Writers must store all other values before f1.
 311   // Readers must test f1 first for non-null before reading other fields.
 312   // Competing writers must acquire exclusive access via a lock.
 313   // A losing writer waits on the lock until the winner writes f1 and leaves
 314   // the lock, so that when the losing writer returns, he can use the linked
 315   // cache entry.
 316 
 317   objArrayHandle resolved_references(Thread::current(), cpool->resolved_references());
 318   // Use the resolved_references() lock for this cpCache entry.
 319   // resolved_references are created for all classes with Invokedynamic, MethodHandle
 320   // or MethodType constant pool cache entries.
 321   assert(resolved_references() != NULL,
 322          "a resolved_references array should have been created for this class");
 323   ObjectLocker ol(resolved_references, Thread::current());
 324   if (!is_f1_null()) {
 325     return;
 326   }
 327 
 328   if (indy_resolution_failed()) {
 329     // Before we got here, another thread got a LinkageError exception during
 330     // resolution.  Ignore our success and throw their exception.
 331     ConstantPoolCache* cpCache = cpool->cache();
 332     int index = -1;
 333     for (int i = 0; i < cpCache->length(); i++) {
 334       if (cpCache->entry_at(i) == this) {
 335         index = i;
 336         break;
 337       }
 338     }
 339     guarantee(index >= 0, "Didn't find cpCache entry!");
 340     int encoded_index = ResolutionErrorTable::encode_cpcache_index(
 341                           ConstantPool::encode_invokedynamic_index(index));
 342     Thread* THREAD = Thread::current();
 343     ConstantPool::throw_resolution_error(cpool, encoded_index, THREAD);
 344     return;
 345   }
 346 
 347   const methodHandle adapter = call_info.resolved_method();
 348   const Handle appendix      = call_info.resolved_appendix();
 349   const Handle method_type   = call_info.resolved_method_type();
 350   const bool has_appendix    = appendix.not_null();
 351   const bool has_method_type = method_type.not_null();
 352 
 353   // Write the flags.
 354   set_method_flags(as_TosState(adapter->result_type()),
 355                    ((has_appendix    ? 1 : 0) << has_appendix_shift   ) |
 356                    ((has_method_type ? 1 : 0) << has_method_type_shift) |
 357                    (                   1      << is_final_shift       ),
 358                    adapter->size_of_parameters());
 359 
 360   if (TraceInvokeDynamic) {
 361     ttyLocker ttyl;
 362     tty->print_cr("set_method_handle bc=%d appendix=" PTR_FORMAT "%s method_type=" PTR_FORMAT "%s method=" PTR_FORMAT " ",
 363                   invoke_code,
 364                   p2i(appendix()),    (has_appendix    ? "" : " (unused)"),
 365                   p2i(method_type()), (has_method_type ? "" : " (unused)"),
 366                   p2i(adapter()));
 367     adapter->print();
 368     if (has_appendix)  appendix()->print();
 369   }
 370 
 371   // Method handle invokes and invokedynamic sites use both cp cache words.
 372   // refs[f2], if not null, contains a value passed as a trailing argument to the adapter.
 373   // In the general case, this could be the call site's MethodType,
 374   // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
 375   // f1 contains the adapter method which manages the actual call.
 376   // In the general case, this is a compiled LambdaForm.
 377   // (The Java code is free to optimize these calls by binding other
 378   // sorts of methods and appendices to call sites.)
 379   // JVM-level linking is via f1, as if for invokespecial, and signatures are erased.
 380   // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
 381   // Even with the appendix, the method will never take more than 255 parameter slots.
 382   //
 383   // This means that given a call site like (List)mh.invoke("foo"),
 384   // the f1 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
 385   // not '(Ljava/lang/String;)Ljava/util/List;'.
 386   // The fact that String and List are involved is encoded in the MethodType in refs[f2].
 387   // This allows us to create fewer Methods, while keeping type safety.
 388   //
 389 
 390   // Store appendix, if any.
 391   if (has_appendix) {
 392     const int appendix_index = f2_as_index() + _indy_resolved_references_appendix_offset;
 393     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
 394     assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
 395     resolved_references->obj_at_put(appendix_index, appendix());
 396   }
 397 
 398   // Store MethodType, if any.
 399   if (has_method_type) {
 400     const int method_type_index = f2_as_index() + _indy_resolved_references_method_type_offset;
 401     assert(method_type_index >= 0 && method_type_index < resolved_references->length(), "oob");
 402     assert(resolved_references->obj_at(method_type_index) == NULL, "init just once");
 403     resolved_references->obj_at_put(method_type_index, method_type());
 404   }
 405 
 406   release_set_f1(adapter());  // This must be the last one to set (see NOTE above)!
 407 
 408   // The interpreter assembly code does not check byte_2,
 409   // but it is used by is_resolved, method_if_resolved, etc.
 410   set_bytecode_1(invoke_code);
 411   NOT_PRODUCT(verify(tty));
 412   if (TraceInvokeDynamic) {
 413     ttyLocker ttyl;
 414     this->print(tty, 0);
 415   }
 416 }
 417 
 418 bool ConstantPoolCacheEntry::save_and_throw_indy_exc(
 419   const constantPoolHandle& cpool, int cpool_index, int index, constantTag tag, TRAPS) {
 420 
 421   assert(HAS_PENDING_EXCEPTION, "No exception got thrown!");
 422   assert(PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass()),
 423          "No LinkageError exception");
 424 
 425   // Use the resolved_references() lock for this cpCache entry.
 426   // resolved_references are created for all classes with Invokedynamic, MethodHandle
 427   // or MethodType constant pool cache entries.
 428   objArrayHandle resolved_references(Thread::current(), cpool->resolved_references());
 429   assert(resolved_references() != NULL,
 430          "a resolved_references array should have been created for this class");
 431   ObjectLocker ol(resolved_references, THREAD);
 432 
 433   // if f1 is not null or the indy_resolution_failed flag is set then another
 434   // thread either succeeded in resolving the method or got a LinkageError
 435   // exception, before this thread was able to record its failure.  So, clear
 436   // this thread's exception and return false so caller can use the earlier
 437   // thread's result.
 438   if (!is_f1_null() || indy_resolution_failed()) {
 439     CLEAR_PENDING_EXCEPTION;
 440     return false;
 441   }
 442 
 443   Symbol* error = PENDING_EXCEPTION->klass()->name();
 444   Symbol* message = java_lang_Throwable::detail_message(PENDING_EXCEPTION);
 445   assert(message != NULL, "Missing detail message");
 446 
 447   SystemDictionary::add_resolution_error(cpool, index, error, message);
 448   set_indy_resolution_failed();
 449   return true;
 450 }
 451 
 452 Method* ConstantPoolCacheEntry::method_if_resolved(const constantPoolHandle& cpool) {
 453   // Decode the action of set_method and set_interface_call
 454   Bytecodes::Code invoke_code = bytecode_1();
 455   if (invoke_code != (Bytecodes::Code)0) {
 456     Metadata* f1 = f1_ord();
 457     if (f1 != NULL) {
 458       switch (invoke_code) {
 459       case Bytecodes::_invokeinterface:
 460         assert(f1->is_klass(), "");
 461         return klassItable::method_for_itable_index((Klass*)f1, f2_as_index());
 462       case Bytecodes::_invokestatic:
 463       case Bytecodes::_invokespecial:
 464         assert(!has_appendix(), "");
 465       case Bytecodes::_invokehandle:
 466       case Bytecodes::_invokedynamic:
 467         assert(f1->is_method(), "");
 468         return (Method*)f1;
 469       default:
 470         break;
 471       }
 472     }
 473   }
 474   invoke_code = bytecode_2();
 475   if (invoke_code != (Bytecodes::Code)0) {
 476     switch (invoke_code) {
 477     case Bytecodes::_invokevirtual:
 478       if (is_vfinal()) {
 479         // invokevirtual
 480         Method* m = f2_as_vfinal_method();
 481         assert(m->is_method(), "");
 482         return m;
 483       } else {
 484         int holder_index = cpool->uncached_klass_ref_index_at(constant_pool_index());
 485         if (cpool->tag_at(holder_index).is_klass()) {
 486           Klass* klass = cpool->resolved_klass_at(holder_index);
 487           return klass->method_at_vtable(f2_as_index());
 488         }
 489       }
 490       break;
 491     default:
 492       break;
 493     }
 494   }
 495   return NULL;
 496 }
 497 
 498 
 499 oop ConstantPoolCacheEntry::appendix_if_resolved(const constantPoolHandle& cpool) {
 500   if (!has_appendix())
 501     return NULL;
 502   const int ref_index = f2_as_index() + _indy_resolved_references_appendix_offset;
 503   objArrayOop resolved_references = cpool->resolved_references();
 504   return resolved_references->obj_at(ref_index);
 505 }
 506 
 507 
 508 oop ConstantPoolCacheEntry::method_type_if_resolved(const constantPoolHandle& cpool) {
 509   if (!has_method_type())
 510     return NULL;
 511   const int ref_index = f2_as_index() + _indy_resolved_references_method_type_offset;
 512   objArrayOop resolved_references = cpool->resolved_references();
 513   return resolved_references->obj_at(ref_index);
 514 }
 515 
 516 
 517 #if INCLUDE_JVMTI
 518 // RedefineClasses() API support:
 519 // If this ConstantPoolCacheEntry refers to old_method then update it
 520 // to refer to new_method.
 521 bool ConstantPoolCacheEntry::adjust_method_entry(Method* old_method,
 522        Method* new_method, bool * trace_name_printed) {
 523 
 524   if (is_vfinal()) {
 525     // virtual and final so _f2 contains method ptr instead of vtable index
 526     if (f2_as_vfinal_method() == old_method) {
 527       // match old_method so need an update
 528       // NOTE: can't use set_f2_as_vfinal_method as it asserts on different values
 529       _f2 = (intptr_t)new_method;
 530       if (log_is_enabled(Info, redefine, class, update)) {
 531         ResourceMark rm;
 532         if (!(*trace_name_printed)) {
 533           log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
 534           *trace_name_printed = true;
 535         }
 536         log_debug(redefine, class, update, constantpool)
 537           ("cpc vf-entry update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
 538       }
 539       return true;
 540     }
 541 
 542     // f1() is not used with virtual entries so bail out
 543     return false;
 544   }
 545 
 546   if (_f1 == NULL) {
 547     // NULL f1() means this is a virtual entry so bail out
 548     // We are assuming that the vtable index does not need change.
 549     return false;
 550   }
 551 
 552   if (_f1 == old_method) {
 553     _f1 = new_method;
 554     if (log_is_enabled(Info, redefine, class, update)) {
 555       ResourceMark rm;
 556       if (!(*trace_name_printed)) {
 557         log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
 558         *trace_name_printed = true;
 559       }
 560       log_debug(redefine, class, update, constantpool)
 561         ("cpc entry update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
 562     }
 563     return true;
 564   }
 565 
 566   return false;
 567 }
 568 
 569 // a constant pool cache entry should never contain old or obsolete methods
 570 bool ConstantPoolCacheEntry::check_no_old_or_obsolete_entries() {
 571   if (is_vfinal()) {
 572     // virtual and final so _f2 contains method ptr instead of vtable index
 573     Metadata* f2 = (Metadata*)_f2;
 574     // Return false if _f2 refers to an old or an obsolete method.
 575     // _f2 == NULL || !_f2->is_method() are just as unexpected here.
 576     return (f2 != NULL NOT_PRODUCT(&& f2->is_valid()) && f2->is_method() &&
 577             !((Method*)f2)->is_old() && !((Method*)f2)->is_obsolete());
 578   } else if (_f1 == NULL ||
 579              (NOT_PRODUCT(_f1->is_valid() &&) !_f1->is_method())) {
 580     // _f1 == NULL || !_f1->is_method() are OK here
 581     return true;
 582   }
 583   // return false if _f1 refers to a non-deleted old or obsolete method
 584   return (NOT_PRODUCT(_f1->is_valid() &&) _f1->is_method() &&
 585           (f1_as_method()->is_deleted() ||
 586           (!f1_as_method()->is_old() && !f1_as_method()->is_obsolete())));
 587 }
 588 
 589 Method* ConstantPoolCacheEntry::get_interesting_method_entry(Klass* k) {
 590   if (!is_method_entry()) {
 591     // not a method entry so not interesting by default
 592     return NULL;
 593   }
 594   Method* m = NULL;
 595   if (is_vfinal()) {
 596     // virtual and final so _f2 contains method ptr instead of vtable index
 597     m = f2_as_vfinal_method();
 598   } else if (is_f1_null()) {
 599     // NULL _f1 means this is a virtual entry so also not interesting
 600     return NULL;
 601   } else {
 602     if (!(_f1->is_method())) {
 603       // _f1 can also contain a Klass* for an interface
 604       return NULL;
 605     }
 606     m = f1_as_method();
 607   }
 608   assert(m != NULL && m->is_method(), "sanity check");
 609   if (m == NULL || !m->is_method() || (k != NULL && m->method_holder() != k)) {
 610     // robustness for above sanity checks or method is not in
 611     // the interesting class
 612     return NULL;
 613   }
 614   // the method is in the interesting class so the entry is interesting
 615   return m;
 616 }
 617 #endif // INCLUDE_JVMTI
 618 
 619 void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
 620   // print separator
 621   if (index == 0) st->print_cr("                 -------------");
 622   // print entry
 623   st->print("%3d  (" PTR_FORMAT ")  ", index, (intptr_t)this);
 624   st->print_cr("[%02x|%02x|%5d]", bytecode_2(), bytecode_1(),
 625                constant_pool_index());
 626   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f1);
 627   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f2);
 628   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_flags);
 629   st->print_cr("                 -------------");
 630 }
 631 
 632 void ConstantPoolCacheEntry::verify(outputStream* st) const {
 633   // not implemented yet
 634 }
 635 
 636 // Implementation of ConstantPoolCache
 637 
 638 ConstantPoolCache* ConstantPoolCache::allocate(ClassLoaderData* loader_data,
 639                                      const intStack& index_map,
 640                                      const intStack& invokedynamic_index_map,
 641                                      const intStack& invokedynamic_map, TRAPS) {
 642 
 643   const int length = index_map.length() + invokedynamic_index_map.length();
 644   int size = ConstantPoolCache::size(length);
 645 
 646   return new (loader_data, size, MetaspaceObj::ConstantPoolCacheType, THREAD)
 647     ConstantPoolCache(length, index_map, invokedynamic_index_map, invokedynamic_map);
 648 }
 649 
 650 void ConstantPoolCache::initialize(const intArray& inverse_index_map,
 651                                    const intArray& invokedynamic_inverse_index_map,
 652                                    const intArray& invokedynamic_references_map) {
 653   for (int i = 0; i < inverse_index_map.length(); i++) {
 654     ConstantPoolCacheEntry* e = entry_at(i);
 655     int original_index = inverse_index_map.at(i);
 656     e->initialize_entry(original_index);
 657     assert(entry_at(i) == e, "sanity");
 658   }
 659 
 660   // Append invokedynamic entries at the end
 661   int invokedynamic_offset = inverse_index_map.length();
 662   for (int i = 0; i < invokedynamic_inverse_index_map.length(); i++) {
 663     int offset = i + invokedynamic_offset;
 664     ConstantPoolCacheEntry* e = entry_at(offset);
 665     int original_index = invokedynamic_inverse_index_map.at(i);
 666     e->initialize_entry(original_index);
 667     assert(entry_at(offset) == e, "sanity");
 668   }
 669 
 670   for (int ref = 0; ref < invokedynamic_references_map.length(); ref++) {
 671     const int cpci = invokedynamic_references_map.at(ref);
 672     if (cpci >= 0) {
 673 #ifdef ASSERT
 674       // invokedynamic and invokehandle have more entries; check if they
 675       // all point to the same constant pool cache entry.
 676       for (int entry = 1; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {
 677         const int cpci_next = invokedynamic_references_map.at(ref + entry);
 678         assert(cpci == cpci_next, "%d == %d", cpci, cpci_next);
 679       }
 680 #endif
 681       entry_at(cpci)->initialize_resolved_reference_index(ref);
 682       ref += ConstantPoolCacheEntry::_indy_resolved_references_entries - 1;  // skip extra entries
 683     }
 684   }
 685 }
 686 
 687 void ConstantPoolCache::verify_just_initialized() {
 688   DEBUG_ONLY(walk_entries_for_initialization(/*check_only = */ true));
 689 }
 690 
 691 void ConstantPoolCache::remove_unshareable_info() {
 692   walk_entries_for_initialization(/*check_only = */ false);
 693 }
 694 
 695 void ConstantPoolCache::walk_entries_for_initialization(bool check_only) {
 696   assert(DumpSharedSpaces, "sanity");
 697   // When dumping the archive, we want to clean up the ConstantPoolCache
 698   // to remove any effect of linking due to the execution of Java code --
 699   // each ConstantPoolCacheEntry will have the same contents as if
 700   // ConstantPoolCache::initialize has just returned:
 701   //
 702   // - We keep the ConstantPoolCache::constant_pool_index() bits for all entries.
 703   // - We keep the "f2" field for entries used by invokedynamic and invokehandle
 704   // - All other bits in the entries are cleared to zero.
 705   ResourceMark rm;
 706 
 707   InstanceKlass* ik = constant_pool()->pool_holder();
 708   bool* f2_used = NEW_RESOURCE_ARRAY(bool, length());
 709   memset(f2_used, 0, sizeof(bool) * length());
 710 
 711   // Find all the slots that we need to preserve f2
 712   for (int i = 0; i < ik->methods()->length(); i++) {
 713     Method* m = ik->methods()->at(i);
 714     RawBytecodeStream bcs(m);
 715     while (!bcs.is_last_bytecode()) {
 716       Bytecodes::Code opcode = bcs.raw_next();
 717       switch (opcode) {
 718       case Bytecodes::_invokedynamic: {
 719           int index = Bytes::get_native_u4(bcs.bcp() + 1);
 720           int cp_cache_index = constant_pool()->invokedynamic_cp_cache_index(index);
 721           f2_used[cp_cache_index] = 1;
 722         }
 723         break;
 724       case Bytecodes::_invokehandle: {
 725           int cp_cache_index = Bytes::get_native_u2(bcs.bcp() + 1);
 726           f2_used[cp_cache_index] = 1;
 727         }
 728         break;
 729       default:
 730         break;
 731       }
 732     }
 733   }
 734 
 735   if (check_only) {
 736     DEBUG_ONLY(
 737       for (int i=0; i<length(); i++) {
 738         entry_at(i)->verify_just_initialized(f2_used[i]);
 739       })
 740   } else {
 741     for (int i=0; i<length(); i++) {
 742       entry_at(i)->reinitialize(f2_used[i]);
 743     }
 744   }
 745 }
 746 
 747 void ConstantPoolCache::deallocate_contents(ClassLoaderData* data) {
 748   assert(!is_shared(), "shared caches are not deallocated");
 749   data->remove_handle(_resolved_references);
 750   set_resolved_references(NULL);
 751   MetadataFactory::free_array<u2>(data, _reference_map);
 752   set_reference_map(NULL);
 753 }
 754 
 755 #if INCLUDE_CDS_JAVA_HEAP
 756 oop ConstantPoolCache::archived_references() {
 757   // Loading an archive root forces the oop to become strongly reachable.
 758   // For example, if it is loaded during concurrent marking in a SATB
 759   // collector, it will be enqueued to the SATB queue, effectively
 760   // shading the previously white object gray.
 761   return RootAccess<IN_ARCHIVE_ROOT>::oop_load(&_archived_references);
 762 }
 763 
 764 void ConstantPoolCache::set_archived_references(oop o) {
 765   assert(DumpSharedSpaces, "called only during runtime");
 766   RootAccess<IN_ARCHIVE_ROOT>::oop_store(&_archived_references, o);
 767 }
 768 #endif
 769 
 770 #if INCLUDE_JVMTI
 771 // RedefineClasses() API support:
 772 // If any entry of this ConstantPoolCache points to any of
 773 // old_methods, replace it with the corresponding new_method.
 774 void ConstantPoolCache::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
 775   for (int i = 0; i < length(); i++) {
 776     ConstantPoolCacheEntry* entry = entry_at(i);
 777     Method* old_method = entry->get_interesting_method_entry(holder);
 778     if (old_method == NULL || !old_method->is_old()) {
 779       continue; // skip uninteresting entries
 780     }
 781     if (old_method->is_deleted()) {
 782       // clean up entries with deleted methods
 783       entry->initialize_entry(entry->constant_pool_index());
 784       continue;
 785     }
 786     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
 787 
 788     assert(new_method != NULL, "method_with_idnum() should not be NULL");
 789     assert(old_method != new_method, "sanity check");
 790 
 791     entry_at(i)->adjust_method_entry(old_method, new_method, trace_name_printed);
 792   }
 793 }
 794 
 795 // the constant pool cache should never contain old or obsolete methods
 796 bool ConstantPoolCache::check_no_old_or_obsolete_entries() {
 797   for (int i = 1; i < length(); i++) {
 798     if (entry_at(i)->get_interesting_method_entry(NULL) != NULL &&
 799         !entry_at(i)->check_no_old_or_obsolete_entries()) {
 800       return false;
 801     }
 802   }
 803   return true;
 804 }
 805 
 806 void ConstantPoolCache::dump_cache() {
 807   for (int i = 1; i < length(); i++) {
 808     if (entry_at(i)->get_interesting_method_entry(NULL) != NULL) {
 809       entry_at(i)->print(tty, i);
 810     }
 811   }
 812 }
 813 #endif // INCLUDE_JVMTI
 814 
 815 void ConstantPoolCache::metaspace_pointers_do(MetaspaceClosure* it) {
 816   log_trace(cds)("Iter(ConstantPoolCache): %p", this);
 817   it->push(&_constant_pool);
 818   it->push(&_reference_map);
 819 }
 820 
 821 // Printing
 822 
 823 void ConstantPoolCache::print_on(outputStream* st) const {
 824   assert(is_constantPoolCache(), "obj must be constant pool cache");
 825   st->print_cr("%s", internal_name());
 826   // print constant pool cache entries
 827   for (int i = 0; i < length(); i++) entry_at(i)->print(st, i);
 828 }
 829 
 830 void ConstantPoolCache::print_value_on(outputStream* st) const {
 831   assert(is_constantPoolCache(), "obj must be constant pool cache");
 832   st->print("cache [%d]", length());
 833   print_address_on(st);
 834   st->print(" for ");
 835   constant_pool()->print_value_on(st);
 836 }
 837 
 838 
 839 // Verification
 840 
 841 void ConstantPoolCache::verify_on(outputStream* st) {
 842   guarantee(is_constantPoolCache(), "obj must be constant pool cache");
 843   // print constant pool cache entries
 844   for (int i = 0; i < length(); i++) entry_at(i)->verify(st);
 845 }