1 /*
   2  * Copyright (c) 1998, 2019, 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/linkResolver.hpp"
  31 #include "interpreter/rewriter.hpp"
  32 #include "logging/log.hpp"
  33 #include "memory/heapShared.hpp"
  34 #include "memory/metadataFactory.hpp"
  35 #include "memory/metaspaceClosure.hpp"
  36 #include "memory/metaspaceShared.hpp"
  37 #include "memory/resourceArea.hpp"
  38 #include "oops/access.inline.hpp"
  39 #include "oops/compressedOops.hpp"
  40 #include "oops/constantPool.inline.hpp"
  41 #include "oops/cpCache.inline.hpp"
  42 #include "oops/objArrayOop.inline.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "prims/methodHandles.hpp"
  45 #include "runtime/atomic.hpp"
  46 #include "runtime/handles.inline.hpp"
  47 #include "runtime/orderAccess.hpp"
  48 #include "utilities/macros.hpp"
  49 
  50 // Implementation of ConstantPoolCacheEntry
  51 
  52 void ConstantPoolCacheEntry::initialize_entry(int index) {
  53   assert(0 < index && index < 0x10000, "sanity check");
  54   _indices = index;
  55   _f1 = NULL;
  56   _f2 = _flags = 0;
  57   assert(constant_pool_index() == index, "");
  58 }
  59 
  60 void ConstantPoolCacheEntry::verify_just_initialized(bool f2_used) {
  61   assert((_indices & (~cp_index_mask)) == 0, "sanity");
  62   assert(_f1 == NULL, "sanity");
  63   assert(_flags == 0, "sanity");
  64   if (!f2_used) {
  65     assert(_f2 == 0, "sanity");
  66   }
  67 }
  68 
  69 void ConstantPoolCacheEntry::reinitialize(bool f2_used) {
  70   _indices &= cp_index_mask;
  71   _f1 = NULL;
  72   _flags = 0;
  73   if (!f2_used) {
  74     _f2 = 0;
  75   }
  76 }
  77 
  78 int ConstantPoolCacheEntry::make_flags(TosState state,
  79                                        int option_bits,
  80                                        int field_index_or_method_params) {
  81   assert(state < number_of_states, "Invalid state in make_flags");
  82   int f = ((int)state << tos_state_shift) | option_bits | field_index_or_method_params;
  83   // Preserve existing flag bit values
  84   // The low bits are a field offset, or else the method parameter size.
  85 #ifdef ASSERT
  86   TosState old_state = flag_state();
  87   assert(old_state == (TosState)0 || old_state == state,
  88          "inconsistent cpCache flags state");
  89 #endif
  90   return (_flags | f) ;
  91 }
  92 
  93 void ConstantPoolCacheEntry::set_bytecode_1(Bytecodes::Code code) {
  94 #ifdef ASSERT
  95   // Read once.
  96   volatile Bytecodes::Code c = bytecode_1();
  97   assert(c == 0 || c == code || code == 0, "update must be consistent");
  98 #endif
  99   // Need to flush pending stores here before bytecode is written.
 100   Atomic::release_store(&_indices, _indices | ((u_char)code << bytecode_1_shift));
 101 }
 102 
 103 void ConstantPoolCacheEntry::set_bytecode_2(Bytecodes::Code code) {
 104 #ifdef ASSERT
 105   // Read once.
 106   volatile Bytecodes::Code c = bytecode_2();
 107   assert(c == 0 || c == code || code == 0, "update must be consistent");
 108 #endif
 109   // Need to flush pending stores here before bytecode is written.
 110   Atomic::release_store(&_indices, _indices | ((u_char)code << bytecode_2_shift));
 111 }
 112 
 113 // Sets f1, ordering with previous writes.
 114 void ConstantPoolCacheEntry::release_set_f1(Metadata* f1) {
 115   assert(f1 != NULL, "");
 116   Atomic::release_store(&_f1, f1);
 117 }
 118 
 119 void ConstantPoolCacheEntry::set_indy_resolution_failed() {
 120   Atomic::release_store(&_flags, _flags | (1 << indy_resolution_failed_shift));
 121 }
 122 
 123 // Note that concurrent update of both bytecodes can leave one of them
 124 // reset to zero.  This is harmless; the interpreter will simply re-resolve
 125 // the damaged entry.  More seriously, the memory synchronization is needed
 126 // to flush other fields (f1, f2) completely to memory before the bytecodes
 127 // are updated, lest other processors see a non-zero bytecode but zero f1/f2.
 128 void ConstantPoolCacheEntry::set_field(Bytecodes::Code get_code,
 129                                        Bytecodes::Code put_code,
 130                                        Klass* field_holder,
 131                                        int field_index,
 132                                        int field_offset,
 133                                        TosState field_type,
 134                                        bool is_final,
 135                                        bool is_volatile,
 136                                        Klass* root_klass) {
 137   set_f1(field_holder);
 138   set_f2(field_offset);
 139   assert((field_index & field_index_mask) == field_index,
 140          "field index does not fit in low flag bits");
 141   set_field_flags(field_type,
 142                   ((is_volatile ? 1 : 0) << is_volatile_shift) |
 143                   ((is_final    ? 1 : 0) << is_final_shift),
 144                   field_index);
 145   set_bytecode_1(get_code);
 146   set_bytecode_2(put_code);
 147   NOT_PRODUCT(verify(tty));
 148 }
 149 
 150 void ConstantPoolCacheEntry::set_parameter_size(int value) {
 151   // This routine is called only in corner cases where the CPCE is not yet initialized.
 152   // See AbstractInterpreter::deopt_continue_after_entry.
 153   assert(_flags == 0 || parameter_size() == 0 || parameter_size() == value,
 154          "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
 155   // Setting the parameter size by itself is only safe if the
 156   // current value of _flags is 0, otherwise another thread may have
 157   // updated it and we don't want to overwrite that value.  Don't
 158   // bother trying to update it once it's nonzero but always make
 159   // sure that the final parameter size agrees with what was passed.
 160   if (_flags == 0) {
 161     intx newflags = (value & parameter_size_mask);
 162     Atomic::cmpxchg(newflags, &_flags, (intx)0);
 163   }
 164   guarantee(parameter_size() == value,
 165             "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
 166 }
 167 
 168 void ConstantPoolCacheEntry::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
 169                                                        const methodHandle& method,
 170                                                        int vtable_index,
 171                                                        bool sender_is_interface) {
 172   bool is_vtable_call = (vtable_index >= 0);  // FIXME: split this method on this boolean
 173   assert(method->interpreter_entry() != NULL, "should have been set at this point");
 174   assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");
 175 
 176   int byte_no = -1;
 177   bool change_to_virtual = false;
 178   InstanceKlass* holder = NULL;  // have to declare this outside the switch
 179   switch (invoke_code) {
 180     case Bytecodes::_invokeinterface:
 181       holder = method->method_holder();
 182       // check for private interface method invocations
 183       if (vtable_index == Method::nonvirtual_vtable_index && holder->is_interface() ) {
 184         assert(method->is_private(), "unexpected non-private method");
 185         assert(method->can_be_statically_bound(), "unexpected non-statically-bound method");
 186         // set_f2_as_vfinal_method checks if is_vfinal flag is true.
 187         set_method_flags(as_TosState(method->result_type()),
 188                          (                             1      << is_vfinal_shift) |
 189                          ((method->is_final_method() ? 1 : 0) << is_final_shift),
 190                          method()->size_of_parameters());
 191         set_f2_as_vfinal_method(method());
 192         byte_no = 2;
 193         set_f1(holder); // interface klass*
 194         break;
 195       }
 196       else {
 197         // We get here from InterpreterRuntime::resolve_invoke when an invokeinterface
 198         // instruction links to a non-interface method (in Object). This can happen when
 199         // an interface redeclares an Object method (like CharSequence declaring toString())
 200         // or when invokeinterface is used explicitly.
 201         // In that case, the method has no itable index and must be invoked as a virtual.
 202         // Set a flag to keep track of this corner case.
 203         assert(holder->is_interface() || holder == SystemDictionary::Object_klass(), "unexpected holder class");
 204         assert(method->is_public(), "Calling non-public method in Object with invokeinterface");
 205         change_to_virtual = true;
 206 
 207         // ...and fall through as if we were handling invokevirtual:
 208       }
 209     case Bytecodes::_invokevirtual:
 210       {
 211         if (!is_vtable_call) {
 212           assert(method->can_be_statically_bound(), "");
 213           // set_f2_as_vfinal_method checks if is_vfinal flag is true.
 214           set_method_flags(as_TosState(method->result_type()),
 215                            (                             1      << is_vfinal_shift) |
 216                            ((method->is_final_method() ? 1 : 0) << is_final_shift)  |
 217                            ((change_to_virtual         ? 1 : 0) << is_forced_virtual_shift),
 218                            method()->size_of_parameters());
 219           set_f2_as_vfinal_method(method());
 220         } else {
 221           assert(!method->can_be_statically_bound(), "");
 222           assert(vtable_index >= 0, "valid index");
 223           assert(!method->is_final_method(), "sanity");
 224           set_method_flags(as_TosState(method->result_type()),
 225                            ((change_to_virtual ? 1 : 0) << is_forced_virtual_shift),
 226                            method()->size_of_parameters());
 227           set_f2(vtable_index);
 228         }
 229         byte_no = 2;
 230         break;
 231       }
 232 
 233     case Bytecodes::_invokespecial:
 234     case Bytecodes::_invokestatic:
 235       assert(!is_vtable_call, "");
 236       // Note:  Read and preserve the value of the is_vfinal flag on any
 237       // invokevirtual bytecode shared with this constant pool cache entry.
 238       // It is cheap and safe to consult is_vfinal() at all times.
 239       // Once is_vfinal is set, it must stay that way, lest we get a dangling oop.
 240       set_method_flags(as_TosState(method->result_type()),
 241                        ((is_vfinal()               ? 1 : 0) << is_vfinal_shift) |
 242                        ((method->is_final_method() ? 1 : 0) << is_final_shift),
 243                        method()->size_of_parameters());
 244       set_f1(method());
 245       byte_no = 1;
 246       break;
 247     default:
 248       ShouldNotReachHere();
 249       break;
 250   }
 251 
 252   // Note:  byte_no also appears in TemplateTable::resolve.
 253   if (byte_no == 1) {
 254     assert(invoke_code != Bytecodes::_invokevirtual &&
 255            invoke_code != Bytecodes::_invokeinterface, "");
 256     bool do_resolve = true;
 257     // Don't mark invokespecial to method as resolved if sender is an interface.  The receiver
 258     // has to be checked that it is a subclass of the current class every time this bytecode
 259     // is executed.
 260     if (invoke_code == Bytecodes::_invokespecial && sender_is_interface &&
 261         method->name() != vmSymbols::object_initializer_name()) {
 262       do_resolve = false;
 263     }
 264     if (invoke_code == Bytecodes::_invokestatic) {
 265       assert(method->method_holder()->is_initialized() ||
 266              method->method_holder()->is_reentrant_initialization(Thread::current()),
 267              "invalid class initialization state for invoke_static");
 268 
 269       if (!VM_Version::supports_fast_class_init_checks() && method->needs_clinit_barrier()) {
 270         // Don't mark invokestatic to method as resolved if the holder class has not yet completed
 271         // initialization. An invokestatic must only proceed if the class is initialized, but if
 272         // we resolve it before then that class initialization check is skipped.
 273         //
 274         // When fast class initialization checks are supported (VM_Version::supports_fast_class_init_checks() == true),
 275         // template interpreter supports fast class initialization check for
 276         // invokestatic which doesn't require call site re-resolution to
 277         // enforce class initialization barrier.
 278         do_resolve = false;
 279       }
 280     }
 281     if (do_resolve) {
 282       set_bytecode_1(invoke_code);
 283     }
 284   } else if (byte_no == 2)  {
 285     if (change_to_virtual) {
 286       assert(invoke_code == Bytecodes::_invokeinterface, "");
 287       // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
 288       //
 289       // Workaround for the case where we encounter an invokeinterface, but we
 290       // should really have an _invokevirtual since the resolved method is a
 291       // virtual method in java.lang.Object. This is a corner case in the spec
 292       // but is presumably legal. javac does not generate this code.
 293       //
 294       // We do not set bytecode_1() to _invokeinterface, because that is the
 295       // bytecode # used by the interpreter to see if it is resolved.  In this
 296       // case, the method gets reresolved with caller for each interface call
 297       // because the actual selected method may not be public.
 298       //
 299       // We set bytecode_2() to _invokevirtual.
 300       // See also interpreterRuntime.cpp. (8/25/2000)
 301     } else {
 302       assert(invoke_code == Bytecodes::_invokevirtual ||
 303              (invoke_code == Bytecodes::_invokeinterface &&
 304               ((method->is_private() ||
 305                 (method->is_final() && method->method_holder() == SystemDictionary::Object_klass())))),
 306              "unexpected invocation mode");
 307       if (invoke_code == Bytecodes::_invokeinterface &&
 308           (method->is_private() || method->is_final())) {
 309         // We set bytecode_1() to _invokeinterface, because that is the
 310         // bytecode # used by the interpreter to see if it is resolved.
 311         // We set bytecode_2() to _invokevirtual.
 312         set_bytecode_1(invoke_code);
 313       }
 314     }
 315     // set up for invokevirtual, even if linking for invokeinterface also:
 316     set_bytecode_2(Bytecodes::_invokevirtual);
 317   } else {
 318     ShouldNotReachHere();
 319   }
 320   NOT_PRODUCT(verify(tty));
 321 }
 322 
 323 void ConstantPoolCacheEntry::set_direct_call(Bytecodes::Code invoke_code, const methodHandle& method,
 324                                              bool sender_is_interface) {
 325   int index = Method::nonvirtual_vtable_index;
 326   // index < 0; FIXME: inline and customize set_direct_or_vtable_call
 327   set_direct_or_vtable_call(invoke_code, method, index, sender_is_interface);
 328 }
 329 
 330 void ConstantPoolCacheEntry::set_vtable_call(Bytecodes::Code invoke_code, const methodHandle& method, int index) {
 331   // either the method is a miranda or its holder should accept the given index
 332   assert(method->method_holder()->is_interface() || method->method_holder()->verify_vtable_index(index), "");
 333   // index >= 0; FIXME: inline and customize set_direct_or_vtable_call
 334   set_direct_or_vtable_call(invoke_code, method, index, false);
 335 }
 336 
 337 void ConstantPoolCacheEntry::set_itable_call(Bytecodes::Code invoke_code,
 338                                              Klass* referenced_klass,
 339                                              const methodHandle& method, int index) {
 340   assert(method->method_holder()->verify_itable_index(index), "");
 341   assert(invoke_code == Bytecodes::_invokeinterface, "");
 342   InstanceKlass* interf = method->method_holder();
 343   assert(interf->is_interface(), "must be an interface");
 344   assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
 345   set_f1(referenced_klass);
 346   set_f2((intx)method());
 347   set_method_flags(as_TosState(method->result_type()),
 348                    0,  // no option bits
 349                    method()->size_of_parameters());
 350   set_bytecode_1(Bytecodes::_invokeinterface);
 351 }
 352 
 353 
 354 void ConstantPoolCacheEntry::set_method_handle(const constantPoolHandle& cpool, const CallInfo &call_info) {
 355   set_method_handle_common(cpool, Bytecodes::_invokehandle, call_info);
 356 }
 357 
 358 void ConstantPoolCacheEntry::set_dynamic_call(const constantPoolHandle& cpool, const CallInfo &call_info) {
 359   set_method_handle_common(cpool, Bytecodes::_invokedynamic, call_info);
 360 }
 361 
 362 void ConstantPoolCacheEntry::set_method_handle_common(const constantPoolHandle& cpool,
 363                                                       Bytecodes::Code invoke_code,
 364                                                       const CallInfo &call_info) {
 365   // NOTE: This CPCE can be the subject of data races.
 366   // There are three words to update: flags, refs[f2], f1 (in that order).
 367   // Writers must store all other values before f1.
 368   // Readers must test f1 first for non-null before reading other fields.
 369   // Competing writers must acquire exclusive access via a lock.
 370   // A losing writer waits on the lock until the winner writes f1 and leaves
 371   // the lock, so that when the losing writer returns, he can use the linked
 372   // cache entry.
 373 
 374   objArrayHandle resolved_references(Thread::current(), cpool->resolved_references());
 375   // Use the resolved_references() lock for this cpCache entry.
 376   // resolved_references are created for all classes with Invokedynamic, MethodHandle
 377   // or MethodType constant pool cache entries.
 378   assert(resolved_references() != NULL,
 379          "a resolved_references array should have been created for this class");
 380   ObjectLocker ol(resolved_references, Thread::current());
 381   if (!is_f1_null()) {
 382     return;
 383   }
 384 
 385   if (indy_resolution_failed()) {
 386     // Before we got here, another thread got a LinkageError exception during
 387     // resolution.  Ignore our success and throw their exception.
 388     ConstantPoolCache* cpCache = cpool->cache();
 389     int index = -1;
 390     for (int i = 0; i < cpCache->length(); i++) {
 391       if (cpCache->entry_at(i) == this) {
 392         index = i;
 393         break;
 394       }
 395     }
 396     guarantee(index >= 0, "Didn't find cpCache entry!");
 397     int encoded_index = ResolutionErrorTable::encode_cpcache_index(
 398                           ConstantPool::encode_invokedynamic_index(index));
 399     Thread* THREAD = Thread::current();
 400     ConstantPool::throw_resolution_error(cpool, encoded_index, THREAD);
 401     return;
 402   }
 403 
 404   Method* adapter            = call_info.resolved_method();
 405   const Handle appendix      = call_info.resolved_appendix();
 406   const bool has_appendix    = appendix.not_null();
 407 
 408   // Write the flags.
 409   // MHs and indy are always sig-poly and have a local signature.
 410   set_method_flags(as_TosState(adapter->result_type()),
 411                    ((has_appendix    ? 1 : 0) << has_appendix_shift        ) |
 412                    (                   1      << has_local_signature_shift ) |
 413                    (                   1      << is_final_shift            ),
 414                    adapter->size_of_parameters());
 415 
 416   if (TraceInvokeDynamic) {
 417     ttyLocker ttyl;
 418     tty->print_cr("set_method_handle bc=%d appendix=" PTR_FORMAT "%s method=" PTR_FORMAT " (local signature) ",
 419                   invoke_code,
 420                   p2i(appendix()),
 421                   (has_appendix ? "" : " (unused)"),
 422                   p2i(adapter));
 423     adapter->print();
 424     if (has_appendix)  appendix()->print();
 425   }
 426 
 427   // Method handle invokes and invokedynamic sites use both cp cache words.
 428   // refs[f2], if not null, contains a value passed as a trailing argument to the adapter.
 429   // In the general case, this could be the call site's MethodType,
 430   // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
 431   // f1 contains the adapter method which manages the actual call.
 432   // In the general case, this is a compiled LambdaForm.
 433   // (The Java code is free to optimize these calls by binding other
 434   // sorts of methods and appendices to call sites.)
 435   // JVM-level linking is via f1, as if for invokespecial, and signatures are erased.
 436   // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
 437   // Even with the appendix, the method will never take more than 255 parameter slots.
 438   //
 439   // This means that given a call site like (List)mh.invoke("foo"),
 440   // the f1 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
 441   // not '(Ljava/lang/String;)Ljava/util/List;'.
 442   // The fact that String and List are involved is encoded in the MethodType in refs[f2].
 443   // This allows us to create fewer Methods, while keeping type safety.
 444   //
 445 
 446   // Store appendix, if any.
 447   if (has_appendix) {
 448     const int appendix_index = f2_as_index();
 449     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
 450     assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
 451     resolved_references->obj_at_put(appendix_index, appendix());
 452   }
 453 
 454   release_set_f1(adapter);  // This must be the last one to set (see NOTE above)!
 455 
 456   // The interpreter assembly code does not check byte_2,
 457   // but it is used by is_resolved, method_if_resolved, etc.
 458   set_bytecode_1(invoke_code);
 459   NOT_PRODUCT(verify(tty));
 460   if (TraceInvokeDynamic) {
 461     ttyLocker ttyl;
 462     this->print(tty, 0);
 463   }
 464 
 465   assert(has_appendix == this->has_appendix(), "proper storage of appendix flag");
 466   assert(this->has_local_signature(), "proper storage of signature flag");
 467 }
 468 
 469 bool ConstantPoolCacheEntry::save_and_throw_indy_exc(
 470   const constantPoolHandle& cpool, int cpool_index, int index, constantTag tag, TRAPS) {
 471 
 472   assert(HAS_PENDING_EXCEPTION, "No exception got thrown!");
 473   assert(PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass()),
 474          "No LinkageError exception");
 475 
 476   // Use the resolved_references() lock for this cpCache entry.
 477   // resolved_references are created for all classes with Invokedynamic, MethodHandle
 478   // or MethodType constant pool cache entries.
 479   objArrayHandle resolved_references(Thread::current(), cpool->resolved_references());
 480   assert(resolved_references() != NULL,
 481          "a resolved_references array should have been created for this class");
 482   ObjectLocker ol(resolved_references, THREAD);
 483 
 484   // if f1 is not null or the indy_resolution_failed flag is set then another
 485   // thread either succeeded in resolving the method or got a LinkageError
 486   // exception, before this thread was able to record its failure.  So, clear
 487   // this thread's exception and return false so caller can use the earlier
 488   // thread's result.
 489   if (!is_f1_null() || indy_resolution_failed()) {
 490     CLEAR_PENDING_EXCEPTION;
 491     return false;
 492   }
 493 
 494   Symbol* error = PENDING_EXCEPTION->klass()->name();
 495   Symbol* message = java_lang_Throwable::detail_message(PENDING_EXCEPTION);
 496 
 497   SystemDictionary::add_resolution_error(cpool, index, error, message);
 498   set_indy_resolution_failed();
 499   return true;
 500 }
 501 
 502 Method* ConstantPoolCacheEntry::method_if_resolved(const constantPoolHandle& cpool) {
 503   // Decode the action of set_method and set_interface_call
 504   Bytecodes::Code invoke_code = bytecode_1();
 505   if (invoke_code != (Bytecodes::Code)0) {
 506     Metadata* f1 = f1_ord();
 507     if (f1 != NULL) {
 508       switch (invoke_code) {
 509       case Bytecodes::_invokeinterface:
 510         assert(f1->is_klass(), "");
 511         return f2_as_interface_method();
 512       case Bytecodes::_invokestatic:
 513       case Bytecodes::_invokespecial:
 514         assert(!has_appendix(), "");
 515       case Bytecodes::_invokehandle:
 516       case Bytecodes::_invokedynamic:
 517         assert(f1->is_method(), "");
 518         return (Method*)f1;
 519       default:
 520         break;
 521       }
 522     }
 523   }
 524   invoke_code = bytecode_2();
 525   if (invoke_code != (Bytecodes::Code)0) {
 526     switch (invoke_code) {
 527     case Bytecodes::_invokevirtual:
 528       if (is_vfinal()) {
 529         // invokevirtual
 530         Method* m = f2_as_vfinal_method();
 531         assert(m->is_method(), "");
 532         return m;
 533       } else {
 534         int holder_index = cpool->uncached_klass_ref_index_at(constant_pool_index());
 535         if (cpool->tag_at(holder_index).is_klass()) {
 536           Klass* klass = cpool->resolved_klass_at(holder_index);
 537           return klass->method_at_vtable(f2_as_index());
 538         }
 539       }
 540       break;
 541     default:
 542       break;
 543     }
 544   }
 545   return NULL;
 546 }
 547 
 548 
 549 oop ConstantPoolCacheEntry::appendix_if_resolved(const constantPoolHandle& cpool) {
 550   if (!has_appendix())
 551     return NULL;
 552   const int ref_index = f2_as_index();
 553   objArrayOop resolved_references = cpool->resolved_references();
 554   return resolved_references->obj_at(ref_index);
 555 }
 556 
 557 
 558 #if INCLUDE_JVMTI
 559 
 560 void log_adjust(const char* entry_type, Method* old_method, Method* new_method, bool* trace_name_printed) {
 561   if (log_is_enabled(Info, redefine, class, update)) {
 562     ResourceMark rm;
 563     if (!(*trace_name_printed)) {
 564       log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
 565       *trace_name_printed = true;
 566     }
 567     log_debug(redefine, class, update, constantpool)
 568           ("cpc %s entry update: %s(%s)", entry_type, new_method->name()->as_C_string(), new_method->signature()->as_C_string());
 569   }
 570 }
 571 
 572 // RedefineClasses() API support:
 573 // If this ConstantPoolCacheEntry refers to old_method then update it
 574 // to refer to new_method.
 575 void ConstantPoolCacheEntry::adjust_method_entry(Method* old_method,
 576        Method* new_method, bool * trace_name_printed) {
 577 
 578   if (is_vfinal()) {
 579     // virtual and final so _f2 contains method ptr instead of vtable index
 580     if (f2_as_vfinal_method() == old_method) {
 581       // match old_method so need an update
 582       // NOTE: can't use set_f2_as_vfinal_method as it asserts on different values
 583       _f2 = (intptr_t)new_method;
 584       log_adjust("vfinal", old_method, new_method, trace_name_printed);
 585     }
 586     return;
 587   }
 588 
 589   assert (_f1 != NULL, "should not call with uninteresting entry");
 590 
 591   if (!(_f1->is_method())) {
 592     // _f1 is a Klass* for an interface, _f2 is the method
 593     if (f2_as_interface_method() == old_method) {
 594       _f2 = (intptr_t)new_method;
 595       log_adjust("interface", old_method, new_method, trace_name_printed);
 596     }
 597   } else if (_f1 == old_method) {
 598     _f1 = new_method;
 599     log_adjust("special, static or dynamic", old_method, new_method, trace_name_printed);
 600   }
 601 }
 602 
 603 // a constant pool cache entry should never contain old or obsolete methods
 604 bool ConstantPoolCacheEntry::check_no_old_or_obsolete_entries() {
 605   Method* m = get_interesting_method_entry();
 606   // return false if m refers to a non-deleted old or obsolete method
 607   if (m != NULL) {
 608     assert(m->is_valid() && m->is_method(), "m is a valid method");
 609     return !m->is_old() && !m->is_obsolete(); // old is always set for old and obsolete
 610   } else {
 611     return true;
 612   }
 613 }
 614 
 615 Method* ConstantPoolCacheEntry::get_interesting_method_entry() {
 616   if (!is_method_entry()) {
 617     // not a method entry so not interesting by default
 618     return NULL;
 619   }
 620   Method* m = NULL;
 621   if (is_vfinal()) {
 622     // virtual and final so _f2 contains method ptr instead of vtable index
 623     m = f2_as_vfinal_method();
 624   } else if (is_f1_null()) {
 625     // NULL _f1 means this is a virtual entry so also not interesting
 626     return NULL;
 627   } else {
 628     if (!(_f1->is_method())) {
 629       // _f1 is a Klass* for an interface
 630       m = f2_as_interface_method();
 631     } else {
 632       m = f1_as_method();
 633     }
 634   }
 635   assert(m != NULL && m->is_method(), "sanity check");
 636   if (m == NULL || !m->is_method()) {
 637     return NULL;
 638   }
 639   return m;
 640 }
 641 #endif // INCLUDE_JVMTI
 642 
 643 void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
 644   // print separator
 645   if (index == 0) st->print_cr("                 -------------");
 646   // print entry
 647   st->print("%3d  (" PTR_FORMAT ")  ", index, (intptr_t)this);
 648   st->print_cr("[%02x|%02x|%5d]", bytecode_2(), bytecode_1(),
 649                constant_pool_index());
 650   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f1);
 651   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f2);
 652   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_flags);
 653   st->print_cr("                 -------------");
 654 }
 655 
 656 void ConstantPoolCacheEntry::verify(outputStream* st) const {
 657   // not implemented yet
 658 }
 659 
 660 // Implementation of ConstantPoolCache
 661 
 662 ConstantPoolCache* ConstantPoolCache::allocate(ClassLoaderData* loader_data,
 663                                      const intStack& index_map,
 664                                      const intStack& invokedynamic_index_map,
 665                                      const intStack& invokedynamic_map, TRAPS) {
 666 
 667   const int length = index_map.length() + invokedynamic_index_map.length();
 668   int size = ConstantPoolCache::size(length);
 669 
 670   return new (loader_data, size, MetaspaceObj::ConstantPoolCacheType, THREAD)
 671     ConstantPoolCache(length, index_map, invokedynamic_index_map, invokedynamic_map);
 672 }
 673 
 674 void ConstantPoolCache::initialize(const intArray& inverse_index_map,
 675                                    const intArray& invokedynamic_inverse_index_map,
 676                                    const intArray& invokedynamic_references_map) {
 677   for (int i = 0; i < inverse_index_map.length(); i++) {
 678     ConstantPoolCacheEntry* e = entry_at(i);
 679     int original_index = inverse_index_map.at(i);
 680     e->initialize_entry(original_index);
 681     assert(entry_at(i) == e, "sanity");
 682   }
 683 
 684   // Append invokedynamic entries at the end
 685   int invokedynamic_offset = inverse_index_map.length();
 686   for (int i = 0; i < invokedynamic_inverse_index_map.length(); i++) {
 687     int offset = i + invokedynamic_offset;
 688     ConstantPoolCacheEntry* e = entry_at(offset);
 689     int original_index = invokedynamic_inverse_index_map.at(i);
 690     e->initialize_entry(original_index);
 691     assert(entry_at(offset) == e, "sanity");
 692   }
 693 
 694   for (int ref = 0; ref < invokedynamic_references_map.length(); ref++) {
 695     const int cpci = invokedynamic_references_map.at(ref);
 696     if (cpci >= 0) {
 697       entry_at(cpci)->initialize_resolved_reference_index(ref);
 698     }
 699   }
 700 }
 701 
 702 void ConstantPoolCache::verify_just_initialized() {
 703   DEBUG_ONLY(walk_entries_for_initialization(/*check_only = */ true));
 704 }
 705 
 706 void ConstantPoolCache::remove_unshareable_info() {
 707   walk_entries_for_initialization(/*check_only = */ false);
 708 }
 709 
 710 void ConstantPoolCache::walk_entries_for_initialization(bool check_only) {
 711   Arguments::assert_is_dumping_archive();
 712   // When dumping the archive, we want to clean up the ConstantPoolCache
 713   // to remove any effect of linking due to the execution of Java code --
 714   // each ConstantPoolCacheEntry will have the same contents as if
 715   // ConstantPoolCache::initialize has just returned:
 716   //
 717   // - We keep the ConstantPoolCache::constant_pool_index() bits for all entries.
 718   // - We keep the "f2" field for entries used by invokedynamic and invokehandle
 719   // - All other bits in the entries are cleared to zero.
 720   ResourceMark rm;
 721 
 722   InstanceKlass* ik = constant_pool()->pool_holder();
 723   bool* f2_used = NEW_RESOURCE_ARRAY(bool, length());
 724   memset(f2_used, 0, sizeof(bool) * length());
 725 
 726   Thread* THREAD = Thread::current();
 727 
 728   // Find all the slots that we need to preserve f2
 729   for (int i = 0; i < ik->methods()->length(); i++) {
 730     Method* m = ik->methods()->at(i);
 731     RawBytecodeStream bcs(methodHandle(THREAD, m));
 732     while (!bcs.is_last_bytecode()) {
 733       Bytecodes::Code opcode = bcs.raw_next();
 734       switch (opcode) {
 735       case Bytecodes::_invokedynamic: {
 736           int index = Bytes::get_native_u4(bcs.bcp() + 1);
 737           int cp_cache_index = constant_pool()->invokedynamic_cp_cache_index(index);
 738           f2_used[cp_cache_index] = 1;
 739         }
 740         break;
 741       case Bytecodes::_invokehandle: {
 742           int cp_cache_index = Bytes::get_native_u2(bcs.bcp() + 1);
 743           f2_used[cp_cache_index] = 1;
 744         }
 745         break;
 746       default:
 747         break;
 748       }
 749     }
 750   }
 751 
 752   if (check_only) {
 753     DEBUG_ONLY(
 754       for (int i=0; i<length(); i++) {
 755         entry_at(i)->verify_just_initialized(f2_used[i]);
 756       })
 757   } else {
 758     for (int i=0; i<length(); i++) {
 759       entry_at(i)->reinitialize(f2_used[i]);
 760     }
 761   }
 762 }
 763 
 764 void ConstantPoolCache::deallocate_contents(ClassLoaderData* data) {
 765   assert(!is_shared(), "shared caches are not deallocated");
 766   data->remove_handle(_resolved_references);
 767   set_resolved_references(NULL);
 768   MetadataFactory::free_array<u2>(data, _reference_map);
 769   set_reference_map(NULL);
 770 }
 771 
 772 #if INCLUDE_CDS_JAVA_HEAP
 773 oop ConstantPoolCache::archived_references() {
 774   if (CompressedOops::is_null(_archived_references)) {
 775     return NULL;
 776   }
 777   return HeapShared::materialize_archived_object(_archived_references);
 778 }
 779 
 780 void ConstantPoolCache::set_archived_references(oop o) {
 781   assert(DumpSharedSpaces, "called only during runtime");
 782   _archived_references = CompressedOops::encode(o);
 783 }
 784 #endif
 785 
 786 #if INCLUDE_JVMTI
 787 // RedefineClasses() API support:
 788 // If any entry of this ConstantPoolCache points to any of
 789 // old_methods, replace it with the corresponding new_method.
 790 void ConstantPoolCache::adjust_method_entries(bool * trace_name_printed) {
 791   for (int i = 0; i < length(); i++) {
 792     ConstantPoolCacheEntry* entry = entry_at(i);
 793     Method* old_method = entry->get_interesting_method_entry();
 794     if (old_method == NULL || !old_method->is_old()) {
 795       continue; // skip uninteresting entries
 796     }
 797     if (old_method->is_deleted()) {
 798       // clean up entries with deleted methods
 799       entry->initialize_entry(entry->constant_pool_index());
 800       continue;
 801     }
 802     Method* new_method = old_method->get_new_method();
 803     entry_at(i)->adjust_method_entry(old_method, new_method, trace_name_printed);
 804   }
 805 }
 806 
 807 // the constant pool cache should never contain old or obsolete methods
 808 bool ConstantPoolCache::check_no_old_or_obsolete_entries() {
 809   for (int i = 1; i < length(); i++) {
 810     if (entry_at(i)->get_interesting_method_entry() != NULL &&
 811         !entry_at(i)->check_no_old_or_obsolete_entries()) {
 812       return false;
 813     }
 814   }
 815   return true;
 816 }
 817 
 818 void ConstantPoolCache::dump_cache() {
 819   for (int i = 1; i < length(); i++) {
 820     if (entry_at(i)->get_interesting_method_entry() != NULL) {
 821       entry_at(i)->print(tty, i);
 822     }
 823   }
 824 }
 825 #endif // INCLUDE_JVMTI
 826 
 827 void ConstantPoolCache::metaspace_pointers_do(MetaspaceClosure* it) {
 828   log_trace(cds)("Iter(ConstantPoolCache): %p", this);
 829   it->push(&_constant_pool);
 830   it->push(&_reference_map);
 831 }
 832 
 833 // Printing
 834 
 835 void ConstantPoolCache::print_on(outputStream* st) const {
 836   st->print_cr("%s", internal_name());
 837   // print constant pool cache entries
 838   for (int i = 0; i < length(); i++) entry_at(i)->print(st, i);
 839 }
 840 
 841 void ConstantPoolCache::print_value_on(outputStream* st) const {
 842   st->print("cache [%d]", length());
 843   print_address_on(st);
 844   st->print(" for ");
 845   constant_pool()->print_value_on(st);
 846 }
 847 
 848 
 849 // Verification
 850 
 851 void ConstantPoolCache::verify_on(outputStream* st) {
 852   // print constant pool cache entries
 853   for (int i = 0; i < length(); i++) entry_at(i)->verify(st);
 854 }