cpCache.cpp

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
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 */

#include "precompiled.hpp"
#include "gc_implementation/shared/markSweep.inline.hpp"
#include "interpreter/interpreter.hpp"
#include "interpreter/rewriter.hpp"
#include "memory/universe.inline.hpp"
#include "oops/cpCache.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oop.inline.hpp"
#include "prims/jvmtiRedefineClassesTrace.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/handles.inline.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_ALL_GCS
# include "gc_implementation/parallelScavenge/psPromotionManager.hpp"
#endif // INCLUDE_ALL_GCS


// Implememtation of ConstantPoolCacheEntry

void ConstantPoolCacheEntry::initialize_entry(int index) {
  assert(0 < index && index < 0x10000, "sanity check");
  _indices = index;
  _f1 = NULL;
  _f2 = _flags = 0;
  assert(constant_pool_index() == index, "");
}

int ConstantPoolCacheEntry::make_flags(TosState state,
                                       int option_bits,
                                       int field_index_or_method_params) {
  assert(state < number_of_states, "Invalid state in make_flags");
  int f = ((int)state << tos_state_shift) | option_bits | field_index_or_method_params;
  // Preserve existing flag bit values
  // The low bits are a field offset, or else the method parameter size.
#ifdef ASSERT
  TosState old_state = flag_state();
  assert(old_state == (TosState)0 || old_state == state,
         "inconsistent cpCache flags state");
#endif
  return (_flags | f) ;
}

void ConstantPoolCacheEntry::set_bytecode_1(Bytecodes::Code code) {
#ifdef ASSERT
  // Read once.
  volatile Bytecodes::Code c = bytecode_1();
  assert(c == 0 || c == code || code == 0, "update must be consistent");
#endif
  // Need to flush pending stores here before bytecode is written.
  OrderAccess::release_store_ptr(&_indices, _indices | ((u_char)code << bytecode_1_shift));
}

void ConstantPoolCacheEntry::set_bytecode_2(Bytecodes::Code code) {
#ifdef ASSERT
  // Read once.
  volatile Bytecodes::Code c = bytecode_2();
  assert(c == 0 || c == code || code == 0, "update must be consistent");
#endif
  // Need to flush pending stores here before bytecode is written.
  OrderAccess::release_store_ptr(&_indices, _indices | ((u_char)code << bytecode_2_shift));
}

// Sets f1, ordering with previous writes.
void ConstantPoolCacheEntry::release_set_f1(Metadata* f1) {
  assert(f1 != NULL, "");
  OrderAccess::release_store_ptr((HeapWord*) &_f1, f1);
}

// Sets flags, but only if the value was previously zero.
bool ConstantPoolCacheEntry::init_flags_atomic(intptr_t flags) {
  intptr_t result = Atomic::cmpxchg_ptr(flags, &_flags, 0);
  return (result == 0);
}

// Note that concurrent update of both bytecodes can leave one of them
// reset to zero.  This is harmless; the interpreter will simply re-resolve
// the damaged entry.  More seriously, the memory synchronization is needed
// to flush other fields (f1, f2) completely to memory before the bytecodes
// are updated, lest other processors see a non-zero bytecode but zero f1/f2.
void ConstantPoolCacheEntry::set_field(Bytecodes::Code get_code,
                                       Bytecodes::Code put_code,
                                       KlassHandle field_holder,
                                       int field_index,
                                       int field_offset,
                                       TosState field_type,
                                       bool is_final,
                                       bool is_volatile,
                                       Klass* root_klass) {
  set_f1(field_holder());
  set_f2(field_offset);
  assert((field_index & field_index_mask) == field_index,
         "field index does not fit in low flag bits");
  set_field_flags(field_type,
                  ((is_volatile ? 1 : 0) << is_volatile_shift) |
                  ((is_final    ? 1 : 0) << is_final_shift),
                  field_index);
  set_bytecode_1(get_code);
  set_bytecode_2(put_code);
  NOT_PRODUCT(verify(tty));
}

void ConstantPoolCacheEntry::set_parameter_size(int value) {
  // This routine is called only in corner cases where the CPCE is not yet initialized.
  // See AbstractInterpreter::deopt_continue_after_entry.
  assert(_flags == 0 || parameter_size() == 0 || parameter_size() == value,
         err_msg("size must not change: parameter_size=%d, value=%d", parameter_size(), value));
  // Setting the parameter size by itself is only safe if the
  // current value of _flags is 0, otherwise another thread may have
  // updated it and we don't want to overwrite that value.  Don't
  // bother trying to update it once it's nonzero but always make
  // sure that the final parameter size agrees with what was passed.
  if (_flags == 0) {
    Atomic::cmpxchg_ptr((value & parameter_size_mask), &_flags, 0);
  }
  guarantee(parameter_size() == value,
            err_msg("size must not change: parameter_size=%d, value=%d", parameter_size(), value));
}

void ConstantPoolCacheEntry::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
                                                       methodHandle method,
                                                       int vtable_index) {
  bool is_vtable_call = (vtable_index >= 0);  // FIXME: split this method on this boolean
  assert(method->interpreter_entry() != NULL, "should have been set at this point");
  assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");

  int byte_no = -1;
  bool change_to_virtual = false;

  switch (invoke_code) {
    case Bytecodes::_invokeinterface:
      // We get here from InterpreterRuntime::resolve_invoke when an invokeinterface
      // instruction somehow links to a non-interface method (in Object).
      // In that case, the method has no itable index and must be invoked as a virtual.
      // Set a flag to keep track of this corner case.
      change_to_virtual = true;

      // ...and fall through as if we were handling invokevirtual:
    case Bytecodes::_invokevirtual:
      {
        if (!is_vtable_call) {
          assert(method->can_be_statically_bound(), "");
          // set_f2_as_vfinal_method checks if is_vfinal flag is true.
          set_method_flags(as_TosState(method->result_type()),
                           (                             1      << is_vfinal_shift) |
                           ((method->is_final_method() ? 1 : 0) << is_final_shift)  |
                           ((change_to_virtual         ? 1 : 0) << is_forced_virtual_shift),
                           method()->size_of_parameters());
          set_f2_as_vfinal_method(method());
        } else {
          assert(!method->can_be_statically_bound(), "");
          assert(vtable_index >= 0, "valid index");
          assert(!method->is_final_method(), "sanity");
          set_method_flags(as_TosState(method->result_type()),
                           ((change_to_virtual ? 1 : 0) << is_forced_virtual_shift),
                           method()->size_of_parameters());
          set_f2(vtable_index);
        }
        byte_no = 2;
        break;
      }

    case Bytecodes::_invokespecial:
    case Bytecodes::_invokestatic:
      assert(!is_vtable_call, "");
      // Note:  Read and preserve the value of the is_vfinal flag on any
      // invokevirtual bytecode shared with this constant pool cache entry.
      // It is cheap and safe to consult is_vfinal() at all times.
      // Once is_vfinal is set, it must stay that way, lest we get a dangling oop.
      set_method_flags(as_TosState(method->result_type()),
                       ((is_vfinal()               ? 1 : 0) << is_vfinal_shift) |
                       ((method->is_final_method() ? 1 : 0) << is_final_shift),
                       method()->size_of_parameters());
      set_f1(method());
      byte_no = 1;
      break;
    default:
      ShouldNotReachHere();
      break;
  }

  // Note:  byte_no also appears in TemplateTable::resolve.
  if (byte_no == 1) {
    assert(invoke_code != Bytecodes::_invokevirtual &&
           invoke_code != Bytecodes::_invokeinterface, "");
    set_bytecode_1(invoke_code);
  } else if (byte_no == 2)  {
    if (change_to_virtual) {
      assert(invoke_code == Bytecodes::_invokeinterface, "");
      // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
      //
      // Workaround for the case where we encounter an invokeinterface, but we
      // should really have an _invokevirtual since the resolved method is a
      // virtual method in java.lang.Object. This is a corner case in the spec
      // but is presumably legal. javac does not generate this code.
      //
      // We set bytecode_1() to _invokeinterface, because that is the
      // bytecode # used by the interpreter to see if it is resolved.
      // We set bytecode_2() to _invokevirtual.
      // See also interpreterRuntime.cpp. (8/25/2000)
      // Only set resolved for the invokeinterface case if method is public.
      // Otherwise, the method needs to be reresolved with caller for each
      // interface call.
      if (method->is_public()) set_bytecode_1(invoke_code);
    } else {
      assert(invoke_code == Bytecodes::_invokevirtual, "");
    }
    // set up for invokevirtual, even if linking for invokeinterface also:
    set_bytecode_2(Bytecodes::_invokevirtual);
  } else {
    ShouldNotReachHere();
  }
  NOT_PRODUCT(verify(tty));
}

void ConstantPoolCacheEntry::set_direct_call(Bytecodes::Code invoke_code, methodHandle method) {
  int index = Method::nonvirtual_vtable_index;
  // index < 0; FIXME: inline and customize set_direct_or_vtable_call
  set_direct_or_vtable_call(invoke_code, method, index);
}

void ConstantPoolCacheEntry::set_vtable_call(Bytecodes::Code invoke_code, methodHandle method, int index) {
  // either the method is a miranda or its holder should accept the given index
  assert(method->method_holder()->is_interface() || method->method_holder()->verify_vtable_index(index), "");
  // index >= 0; FIXME: inline and customize set_direct_or_vtable_call
  set_direct_or_vtable_call(invoke_code, method, index);
}

void ConstantPoolCacheEntry::set_itable_call(Bytecodes::Code invoke_code, methodHandle method, int index) {
  assert(method->method_holder()->verify_itable_index(index), "");
  assert(invoke_code == Bytecodes::_invokeinterface, "");
  InstanceKlass* interf = method->method_holder();
  assert(interf->is_interface(), "must be an interface");
  assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
  set_f1(interf);
  set_f2(index);
  set_method_flags(as_TosState(method->result_type()),
                   0,  // no option bits
                   method()->size_of_parameters());
  set_bytecode_1(Bytecodes::_invokeinterface);
}


void ConstantPoolCacheEntry::set_method_handle(constantPoolHandle cpool, const CallInfo &call_info) {
  set_method_handle_common(cpool, Bytecodes::_invokehandle, call_info);
}

void ConstantPoolCacheEntry::set_dynamic_call(constantPoolHandle cpool, const CallInfo &call_info) {
  set_method_handle_common(cpool, Bytecodes::_invokedynamic, call_info);
}

void ConstantPoolCacheEntry::set_method_handle_common(constantPoolHandle cpool,
                                                      Bytecodes::Code invoke_code,
                                                      const CallInfo &call_info) {
  // NOTE: This CPCE can be the subject of data races.
  // There are three words to update: flags, refs[f2], f1 (in that order).
  // Writers must store all other values before f1.
  // Readers must test f1 first for non-null before reading other fields.
  // Competing writers must acquire exclusive access via a lock.
  // A losing writer waits on the lock until the winner writes f1 and leaves
  // the lock, so that when the losing writer returns, he can use the linked
  // cache entry.

  MonitorLockerEx ml(cpool->lock());
  if (!is_f1_null()) {
    return;
  }

  const methodHandle adapter = call_info.resolved_method();
  const Handle appendix      = call_info.resolved_appendix();
  const Handle method_type   = call_info.resolved_method_type();
  const bool has_appendix    = appendix.not_null();
  const bool has_method_type = method_type.not_null();

  // Write the flags.
  set_method_flags(as_TosState(adapter->result_type()),
                   ((has_appendix    ? 1 : 0) << has_appendix_shift   ) |
                   ((has_method_type ? 1 : 0) << has_method_type_shift) |
                   (                   1      << is_final_shift       ),
                   adapter->size_of_parameters());

  if (TraceInvokeDynamic) {
    tty->print_cr("set_method_handle bc=%d appendix="PTR_FORMAT"%s method_type="PTR_FORMAT"%s method="PTR_FORMAT" ",
                  invoke_code,
                  (void *)appendix(),    (has_appendix    ? "" : " (unused)"),
                  (void *)method_type(), (has_method_type ? "" : " (unused)"),
                  (intptr_t)adapter());
    adapter->print();
    if (has_appendix)  appendix()->print();
  }

  // Method handle invokes and invokedynamic sites use both cp cache words.
  // refs[f2], if not null, contains a value passed as a trailing argument to the adapter.
  // In the general case, this could be the call site's MethodType,
  // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
  // f1 contains the adapter method which manages the actual call.
  // In the general case, this is a compiled LambdaForm.
  // (The Java code is free to optimize these calls by binding other
  // sorts of methods and appendices to call sites.)
  // JVM-level linking is via f1, as if for invokespecial, and signatures are erased.
  // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
  // Even with the appendix, the method will never take more than 255 parameter slots.
  //
  // This means that given a call site like (List)mh.invoke("foo"),
  // the f1 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
  // not '(Ljava/lang/String;)Ljava/util/List;'.
  // The fact that String and List are involved is encoded in the MethodType in refs[f2].
  // This allows us to create fewer method oops, while keeping type safety.
  //

  objArrayHandle resolved_references = cpool->resolved_references();
  // Store appendix, if any.
  if (has_appendix) {
    const int appendix_index = f2_as_index() + _indy_resolved_references_appendix_offset;
    assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
    assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
    resolved_references->obj_at_put(appendix_index, appendix());
  }

  // Store MethodType, if any.
  if (has_method_type) {
    const int method_type_index = f2_as_index() + _indy_resolved_references_method_type_offset;
    assert(method_type_index >= 0 && method_type_index < resolved_references->length(), "oob");
    assert(resolved_references->obj_at(method_type_index) == NULL, "init just once");
    resolved_references->obj_at_put(method_type_index, method_type());
  }

  release_set_f1(adapter());  // This must be the last one to set (see NOTE above)!

  // The interpreter assembly code does not check byte_2,
  // but it is used by is_resolved, method_if_resolved, etc.
  set_bytecode_1(invoke_code);
  NOT_PRODUCT(verify(tty));
  if (TraceInvokeDynamic) {
    this->print(tty, 0);
  }
}

Method* ConstantPoolCacheEntry::method_if_resolved(constantPoolHandle cpool) {
  // Decode the action of set_method and set_interface_call
  Bytecodes::Code invoke_code = bytecode_1();
  if (invoke_code != (Bytecodes::Code)0) {
    Metadata* f1 = (Metadata*)_f1;
    if (f1 != NULL) {
      switch (invoke_code) {
      case Bytecodes::_invokeinterface:
        assert(f1->is_klass(), "");
        return klassItable::method_for_itable_index((Klass*)f1, f2_as_index());
      case Bytecodes::_invokestatic:
      case Bytecodes::_invokespecial:
        assert(!has_appendix(), "");
      case Bytecodes::_invokehandle:
      case Bytecodes::_invokedynamic:
        assert(f1->is_method(), "");
        return (Method*)f1;
      }
    }
  }
  invoke_code = bytecode_2();
  if (invoke_code != (Bytecodes::Code)0) {
    switch (invoke_code) {
    case Bytecodes::_invokevirtual:
      if (is_vfinal()) {
        // invokevirtual
        Method* m = f2_as_vfinal_method();
        assert(m->is_method(), "");
        return m;
      } else {
        int holder_index = cpool->uncached_klass_ref_index_at(constant_pool_index());
        if (cpool->tag_at(holder_index).is_klass()) {
          Klass* klass = cpool->resolved_klass_at(holder_index);
          if (!klass->oop_is_instance())
            klass = SystemDictionary::Object_klass();
          return InstanceKlass::cast(klass)->method_at_vtable(f2_as_index());
        }
      }
      break;
    }
  }
  return NULL;
}


oop ConstantPoolCacheEntry::appendix_if_resolved(constantPoolHandle cpool) {
  if (is_f1_null() || !has_appendix())
    return NULL;
  const int ref_index = f2_as_index() + _indy_resolved_references_appendix_offset;
  objArrayOop resolved_references = cpool->resolved_references();
  return resolved_references->obj_at(ref_index);
}


oop ConstantPoolCacheEntry::method_type_if_resolved(constantPoolHandle cpool) {
  if (is_f1_null() || !has_method_type())
    return NULL;
  const int ref_index = f2_as_index() + _indy_resolved_references_method_type_offset;
  objArrayOop resolved_references = cpool->resolved_references();
  return resolved_references->obj_at(ref_index);
}


#if INCLUDE_JVMTI
// RedefineClasses() API support:
// If this ConstantPoolCacheEntry refers to old_method then update it
// to refer to new_method.
bool ConstantPoolCacheEntry::adjust_method_entry(Method* old_method,
       Method* new_method, bool * trace_name_printed) {

  if (is_vfinal()) {
    // virtual and final so _f2 contains method ptr instead of vtable index
    if (f2_as_vfinal_method() == old_method) {
      // match old_method so need an update
      // NOTE: can't use set_f2_as_vfinal_method as it asserts on different values
      _f2 = (intptr_t)new_method;
      if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
        if (!(*trace_name_printed)) {
          // RC_TRACE_MESG macro has an embedded ResourceMark
          RC_TRACE_MESG(("adjust: name=%s",
            old_method->method_holder()->external_name()));
          *trace_name_printed = true;
        }
        // RC_TRACE macro has an embedded ResourceMark
        RC_TRACE(0x00400000, ("cpc vf-entry update: %s(%s)",
          new_method->name()->as_C_string(),
          new_method->signature()->as_C_string()));
      }

      return true;
    }

    // f1() is not used with virtual entries so bail out
    return false;
  }

  if (_f1 == NULL) {
    // NULL f1() means this is a virtual entry so bail out
    // We are assuming that the vtable index does not need change.
    return false;
  }

  if (_f1 == old_method) {
    _f1 = new_method;
    if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
      if (!(*trace_name_printed)) {
        // RC_TRACE_MESG macro has an embedded ResourceMark
        RC_TRACE_MESG(("adjust: name=%s",
          old_method->method_holder()->external_name()));
        *trace_name_printed = true;
      }
      // RC_TRACE macro has an embedded ResourceMark
      RC_TRACE(0x00400000, ("cpc entry update: %s(%s)",
        new_method->name()->as_C_string(),
        new_method->signature()->as_C_string()));
    }

    return true;
  }

  return false;
}

// a constant pool cache entry should never contain old or obsolete methods
bool ConstantPoolCacheEntry::check_no_old_or_obsolete_entries() {
  if (is_vfinal()) {
    // virtual and final so _f2 contains method ptr instead of vtable index
    Metadata* f2 = (Metadata*)_f2;
    // Return false if _f2 refers to an old or an obsolete method.
    // _f2 == NULL || !_f2->is_method() are just as unexpected here.
    return (f2 != NULL NOT_PRODUCT(&& f2->is_valid()) && f2->is_method() &&
            !((Method*)f2)->is_old() && !((Method*)f2)->is_obsolete());
  } else if (_f1 == NULL ||
             (NOT_PRODUCT(_f1->is_valid() &&) !_f1->is_method())) {
    // _f1 == NULL || !_f1->is_method() are OK here
    return true;
  }
  // return false if _f1 refers to an old or an obsolete method
  return (NOT_PRODUCT(_f1->is_valid() &&) _f1->is_method() &&
          !((Method*)_f1)->is_old() && !((Method*)_f1)->is_obsolete());
}

bool ConstantPoolCacheEntry::is_interesting_method_entry(Klass* k) {
  if (!is_method_entry()) {
    // not a method entry so not interesting by default
    return false;
  }

  Method* m = NULL;
  if (is_vfinal()) {
    // virtual and final so _f2 contains method ptr instead of vtable index
    m = f2_as_vfinal_method();
  } else if (is_f1_null()) {
    // NULL _f1 means this is a virtual entry so also not interesting
    return false;
  } else {
    if (!(_f1->is_method())) {
      // _f1 can also contain a Klass* for an interface
      return false;
    }
    m = f1_as_method();
  }

  assert(m != NULL && m->is_method(), "sanity check");
  if (m == NULL || !m->is_method() || (k != NULL && m->method_holder() != k)) {
    // robustness for above sanity checks or method is not in
    // the interesting class
    return false;
  }

  // the method is in the interesting class so the entry is interesting
  return true;
}
#endif // INCLUDE_JVMTI

void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
  // print separator
  if (index == 0) st->print_cr("                 -------------");
  // print entry
  st->print("%3d  ("PTR_FORMAT")  ", index, (intptr_t)this);
  st->print_cr("[%02x|%02x|%5d]", bytecode_2(), bytecode_1(),
               constant_pool_index());
  st->print_cr("                 [   "PTR_FORMAT"]", (intptr_t)_f1);
  st->print_cr("                 [   "PTR_FORMAT"]", (intptr_t)_f2);
  st->print_cr("                 [   "PTR_FORMAT"]", (intptr_t)_flags);
  st->print_cr("                 -------------");
}

void ConstantPoolCacheEntry::verify(outputStream* st) const {
  // not implemented yet
}

// Implementation of ConstantPoolCache

ConstantPoolCache* ConstantPoolCache::allocate(ClassLoaderData* loader_data,
                                     const intStack& index_map,
                                     const intStack& invokedynamic_index_map,
                                     const intStack& invokedynamic_map, TRAPS) {

  const int length = index_map.length() + invokedynamic_index_map.length();
  int size = ConstantPoolCache::size(length);

  return new (loader_data, size, false, MetaspaceObj::ConstantPoolCacheType, THREAD)
    ConstantPoolCache(length, index_map, invokedynamic_index_map, invokedynamic_map);
}

void ConstantPoolCache::initialize(const intArray& inverse_index_map,
                                   const intArray& invokedynamic_inverse_index_map,
                                   const intArray& invokedynamic_references_map) {
  for (int i = 0; i < inverse_index_map.length(); i++) {
    ConstantPoolCacheEntry* e = entry_at(i);
    int original_index = inverse_index_map[i];
    e->initialize_entry(original_index);
    assert(entry_at(i) == e, "sanity");
  }

  // Append invokedynamic entries at the end
  int invokedynamic_offset = inverse_index_map.length();
  for (int i = 0; i < invokedynamic_inverse_index_map.length(); i++) {
    int offset = i + invokedynamic_offset;
    ConstantPoolCacheEntry* e = entry_at(offset);
    int original_index = invokedynamic_inverse_index_map[i];
    e->initialize_entry(original_index);
    assert(entry_at(offset) == e, "sanity");
  }

  for (int ref = 0; ref < invokedynamic_references_map.length(); ref++) {
    const int cpci = invokedynamic_references_map[ref];
    if (cpci >= 0) {
#ifdef ASSERT
      // invokedynamic and invokehandle have more entries; check if they
      // all point to the same constant pool cache entry.
      for (int entry = 1; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {
        const int cpci_next = invokedynamic_references_map[ref + entry];
        assert(cpci == cpci_next, err_msg_res("%d == %d", cpci, cpci_next));
      }
#endif
      entry_at(cpci)->initialize_resolved_reference_index(ref);
      ref += ConstantPoolCacheEntry::_indy_resolved_references_entries - 1;  // skip extra entries
    }
  }
}

#if INCLUDE_JVMTI
// RedefineClasses() API support:
// If any entry of this ConstantPoolCache points to any of
// old_methods, replace it with the corresponding new_method.
void ConstantPoolCache::adjust_method_entries(Method** old_methods, Method** new_methods,
                                                     int methods_length, bool * trace_name_printed) {

  if (methods_length == 0) {
    // nothing to do if there are no methods
    return;
  }

  // get shorthand for the interesting class
  Klass* old_holder = old_methods[0]->method_holder();

  for (int i = 0; i < length(); i++) {
    if (!entry_at(i)->is_interesting_method_entry(old_holder)) {
      // skip uninteresting methods
      continue;
    }

    // The ConstantPoolCache contains entries for several different
    // things, but we only care about methods. In fact, we only care
    // about methods in the same class as the one that contains the
    // old_methods. At this point, we have an interesting entry.

    for (int j = 0; j < methods_length; j++) {
      Method* old_method = old_methods[j];
      Method* new_method = new_methods[j];

      if (entry_at(i)->adjust_method_entry(old_method, new_method,
          trace_name_printed)) {
        // current old_method matched this entry and we updated it so
        // break out and get to the next interesting entry if there one
        break;
      }
    }
  }
}

// the constant pool cache should never contain old or obsolete methods
bool ConstantPoolCache::check_no_old_or_obsolete_entries() {
  for (int i = 1; i < length(); i++) {
    if (entry_at(i)->is_interesting_method_entry(NULL) &&
        !entry_at(i)->check_no_old_or_obsolete_entries()) {
      return false;
    }
  }
  return true;
}

void ConstantPoolCache::dump_cache() {
  for (int i = 1; i < length(); i++) {
    if (entry_at(i)->is_interesting_method_entry(NULL)) {
      entry_at(i)->print(tty, i);
    }
  }
}
#endif // INCLUDE_JVMTI


// Printing

void ConstantPoolCache::print_on(outputStream* st) const {
  assert(is_constantPoolCache(), "obj must be constant pool cache");
  st->print_cr(internal_name());
  // print constant pool cache entries
  for (int i = 0; i < length(); i++) entry_at(i)->print(st, i);
}

void ConstantPoolCache::print_value_on(outputStream* st) const {
  assert(is_constantPoolCache(), "obj must be constant pool cache");
  st->print("cache [%d]", length());
  print_address_on(st);
  st->print(" for ");
  constant_pool()->print_value_on(st);
}


// Verification

void ConstantPoolCache::verify_on(outputStream* st) {
  guarantee(is_constantPoolCache(), "obj must be constant pool cache");
  // print constant pool cache entries
  for (int i = 0; i < length(); i++) entry_at(i)->verify(st);
}