Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1998, 2012, 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

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #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;

   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_method(Bytecodes::Code invoke_code,

                                         methodHandle method,

                                         int vtable_index) {

   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 (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(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:

       // 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_interface_call(methodHandle method, int index) {

   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,

                   (intptr_t)appendix(),    (has_appendix    ? "" : " (unused)"),

                   (intptr_t)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);

 }

 // 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;

 }

 #ifndef PRODUCT

 bool ConstantPoolCacheEntry::check_no_old_entries() {

   if (is_vfinal()) {

     Metadata* f2 = (Metadata*)_f2;

     return (f2->is_valid() && f2->is_method() && !((Method*)f2)->is_old());

   } else {

     return (_f1 == NULL || (_f1->is_valid() && _f1->is_method() && !((Method*)_f1)->is_old()));

   }

 }

 #endif

 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;

 }

 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, int length, TRAPS) {

   int size = ConstantPoolCache::size(length);

   return new (loader_data, size, false, THREAD) ConstantPoolCache(length);

 }

 void ConstantPoolCache::initialize(intArray& inverse_index_map, intArray& invokedynamic_references_map) {

   assert(inverse_index_map.length() == length(), "inverse index map must have same length as cache");

   for (int i = 0; i < 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");

   }

   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

     }

   }

 }

 // 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;

       }

     }

   }

 }

 #ifndef PRODUCT

 bool ConstantPoolCache::check_no_old_entries() {

   for (int i = 1; i < length(); i++) {

     if (entry_at(i)->is_interesting_method_entry(NULL) &&

        !entry_at(i)->check_no_old_entries()) {

       return false;

     }

   }

   return true;

 }

 #endif // PRODUCT

 // 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);

 }