src/share/vm/prims/jvmtiRedefineClasses.cpp

Mon, 13 May 2013 15:37:08 -0400

author
coleenp
date
Mon, 13 May 2013 15:37:08 -0400
changeset 5100
43083e670adf
parent 5084
712a1e9c91f3
child 5214
e7d29a019a3c
permissions
-rw-r--r--

8005056: NPG: Crash after redefining java.lang.Object
Summary: Need to walk array class vtables replacing old methods too if j.l.o redefined
Reviewed-by: sspitsyn, dcubed, ctornqvi

     1 /*
     2  * Copyright (c) 2003, 2013, 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  */
    25 #include "precompiled.hpp"
    26 #include "classfile/metadataOnStackMark.hpp"
    27 #include "classfile/systemDictionary.hpp"
    28 #include "classfile/verifier.hpp"
    29 #include "code/codeCache.hpp"
    30 #include "compiler/compileBroker.hpp"
    31 #include "interpreter/oopMapCache.hpp"
    32 #include "interpreter/rewriter.hpp"
    33 #include "memory/gcLocker.hpp"
    34 #include "memory/metadataFactory.hpp"
    35 #include "memory/metaspaceShared.hpp"
    36 #include "memory/universe.inline.hpp"
    37 #include "oops/fieldStreams.hpp"
    38 #include "oops/klassVtable.hpp"
    39 #include "prims/jvmtiImpl.hpp"
    40 #include "prims/jvmtiRedefineClasses.hpp"
    41 #include "prims/methodComparator.hpp"
    42 #include "runtime/deoptimization.hpp"
    43 #include "runtime/relocator.hpp"
    44 #include "utilities/bitMap.inline.hpp"
    47 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
    48 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
    49 Method**  VM_RedefineClasses::_matching_old_methods = NULL;
    50 Method**  VM_RedefineClasses::_matching_new_methods = NULL;
    51 Method**  VM_RedefineClasses::_deleted_methods      = NULL;
    52 Method**  VM_RedefineClasses::_added_methods        = NULL;
    53 int         VM_RedefineClasses::_matching_methods_length = 0;
    54 int         VM_RedefineClasses::_deleted_methods_length  = 0;
    55 int         VM_RedefineClasses::_added_methods_length    = 0;
    56 Klass*      VM_RedefineClasses::_the_class_oop = NULL;
    59 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
    60                                        const jvmtiClassDefinition *class_defs,
    61                                        JvmtiClassLoadKind class_load_kind) {
    62   _class_count = class_count;
    63   _class_defs = class_defs;
    64   _class_load_kind = class_load_kind;
    65   _res = JVMTI_ERROR_NONE;
    66 }
    68 bool VM_RedefineClasses::doit_prologue() {
    69   if (_class_count == 0) {
    70     _res = JVMTI_ERROR_NONE;
    71     return false;
    72   }
    73   if (_class_defs == NULL) {
    74     _res = JVMTI_ERROR_NULL_POINTER;
    75     return false;
    76   }
    77   for (int i = 0; i < _class_count; i++) {
    78     if (_class_defs[i].klass == NULL) {
    79       _res = JVMTI_ERROR_INVALID_CLASS;
    80       return false;
    81     }
    82     if (_class_defs[i].class_byte_count == 0) {
    83       _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
    84       return false;
    85     }
    86     if (_class_defs[i].class_bytes == NULL) {
    87       _res = JVMTI_ERROR_NULL_POINTER;
    88       return false;
    89     }
    90   }
    92   // Start timer after all the sanity checks; not quite accurate, but
    93   // better than adding a bunch of stop() calls.
    94   RC_TIMER_START(_timer_vm_op_prologue);
    96   // We first load new class versions in the prologue, because somewhere down the
    97   // call chain it is required that the current thread is a Java thread.
    98   _res = load_new_class_versions(Thread::current());
    99   if (_res != JVMTI_ERROR_NONE) {
   100     // free any successfully created classes, since none are redefined
   101     for (int i = 0; i < _class_count; i++) {
   102       if (_scratch_classes[i] != NULL) {
   103         ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
   104         // Free the memory for this class at class unloading time.  Not before
   105         // because CMS might think this is still live.
   106         cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
   107       }
   108     }
   109     // Free os::malloc allocated memory in load_new_class_version.
   110     os::free(_scratch_classes);
   111     RC_TIMER_STOP(_timer_vm_op_prologue);
   112     return false;
   113   }
   115   RC_TIMER_STOP(_timer_vm_op_prologue);
   116   return true;
   117 }
   119 void VM_RedefineClasses::doit() {
   120   Thread *thread = Thread::current();
   122   if (UseSharedSpaces) {
   123     // Sharing is enabled so we remap the shared readonly space to
   124     // shared readwrite, private just in case we need to redefine
   125     // a shared class. We do the remap during the doit() phase of
   126     // the safepoint to be safer.
   127     if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
   128       RC_TRACE_WITH_THREAD(0x00000001, thread,
   129         ("failed to remap shared readonly space to readwrite, private"));
   130       _res = JVMTI_ERROR_INTERNAL;
   131       return;
   132     }
   133   }
   135   // Mark methods seen on stack and everywhere else so old methods are not
   136   // cleaned up if they're on the stack.
   137   MetadataOnStackMark md_on_stack;
   138   HandleMark hm(thread);   // make sure any handles created are deleted
   139                            // before the stack walk again.
   141   for (int i = 0; i < _class_count; i++) {
   142     redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
   143     ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
   144     // Free the memory for this class at class unloading time.  Not before
   145     // because CMS might think this is still live.
   146     cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
   147     _scratch_classes[i] = NULL;
   148   }
   150   // Disable any dependent concurrent compilations
   151   SystemDictionary::notice_modification();
   153   // Set flag indicating that some invariants are no longer true.
   154   // See jvmtiExport.hpp for detailed explanation.
   155   JvmtiExport::set_has_redefined_a_class();
   157 // check_class() is optionally called for product bits, but is
   158 // always called for non-product bits.
   159 #ifdef PRODUCT
   160   if (RC_TRACE_ENABLED(0x00004000)) {
   161 #endif
   162     RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
   163     CheckClass check_class(thread);
   164     ClassLoaderDataGraph::classes_do(&check_class);
   165 #ifdef PRODUCT
   166   }
   167 #endif
   168 }
   170 void VM_RedefineClasses::doit_epilogue() {
   171   // Free os::malloc allocated memory.
   172   os::free(_scratch_classes);
   174   if (RC_TRACE_ENABLED(0x00000004)) {
   175     // Used to have separate timers for "doit" and "all", but the timer
   176     // overhead skewed the measurements.
   177     jlong doit_time = _timer_rsc_phase1.milliseconds() +
   178                       _timer_rsc_phase2.milliseconds();
   179     jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
   181     RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
   182       "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
   183       _timer_vm_op_prologue.milliseconds(), doit_time));
   184     RC_TRACE(0x00000004,
   185       ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
   186        _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
   187   }
   188 }
   190 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
   191   // classes for primitives cannot be redefined
   192   if (java_lang_Class::is_primitive(klass_mirror)) {
   193     return false;
   194   }
   195   Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
   196   // classes for arrays cannot be redefined
   197   if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
   198     return false;
   199   }
   200   return true;
   201 }
   203 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
   204 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
   205 // direct CP entries, there is just the current entry to append. For
   206 // indirect and double-indirect CP entries, there are zero or more
   207 // referenced CP entries along with the current entry to append.
   208 // Indirect and double-indirect CP entries are handled by recursive
   209 // calls to append_entry() as needed. The referenced CP entries are
   210 // always appended to *merge_cp_p before the referee CP entry. These
   211 // referenced CP entries may already exist in *merge_cp_p in which case
   212 // there is nothing extra to append and only the current entry is
   213 // appended.
   214 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
   215        int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
   216        TRAPS) {
   218   // append is different depending on entry tag type
   219   switch (scratch_cp->tag_at(scratch_i).value()) {
   221     // The old verifier is implemented outside the VM. It loads classes,
   222     // but does not resolve constant pool entries directly so we never
   223     // see Class entries here with the old verifier. Similarly the old
   224     // verifier does not like Class entries in the input constant pool.
   225     // The split-verifier is implemented in the VM so it can optionally
   226     // and directly resolve constant pool entries to load classes. The
   227     // split-verifier can accept either Class entries or UnresolvedClass
   228     // entries in the input constant pool. We revert the appended copy
   229     // back to UnresolvedClass so that either verifier will be happy
   230     // with the constant pool entry.
   231     case JVM_CONSTANT_Class:
   232     {
   233       // revert the copy to JVM_CONSTANT_UnresolvedClass
   234       (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
   235         scratch_cp->klass_name_at(scratch_i));
   237       if (scratch_i != *merge_cp_length_p) {
   238         // The new entry in *merge_cp_p is at a different index than
   239         // the new entry in scratch_cp so we need to map the index values.
   240         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   241       }
   242       (*merge_cp_length_p)++;
   243     } break;
   245     // these are direct CP entries so they can be directly appended,
   246     // but double and long take two constant pool entries
   247     case JVM_CONSTANT_Double:  // fall through
   248     case JVM_CONSTANT_Long:
   249     {
   250       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
   251         THREAD);
   253       if (scratch_i != *merge_cp_length_p) {
   254         // The new entry in *merge_cp_p is at a different index than
   255         // the new entry in scratch_cp so we need to map the index values.
   256         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   257       }
   258       (*merge_cp_length_p) += 2;
   259     } break;
   261     // these are direct CP entries so they can be directly appended
   262     case JVM_CONSTANT_Float:   // fall through
   263     case JVM_CONSTANT_Integer: // fall through
   264     case JVM_CONSTANT_Utf8:    // fall through
   266     // This was an indirect CP entry, but it has been changed into
   267     // Symbol*s so this entry can be directly appended.
   268     case JVM_CONSTANT_String:      // fall through
   270     // These were indirect CP entries, but they have been changed into
   271     // Symbol*s so these entries can be directly appended.
   272     case JVM_CONSTANT_UnresolvedClass:  // fall through
   273     {
   274       ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
   275         THREAD);
   277       if (scratch_i != *merge_cp_length_p) {
   278         // The new entry in *merge_cp_p is at a different index than
   279         // the new entry in scratch_cp so we need to map the index values.
   280         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   281       }
   282       (*merge_cp_length_p)++;
   283     } break;
   285     // this is an indirect CP entry so it needs special handling
   286     case JVM_CONSTANT_NameAndType:
   287     {
   288       int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
   289       int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
   290                                                          merge_cp_length_p, THREAD);
   292       int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
   293       int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
   294                                                               merge_cp_p, merge_cp_length_p,
   295                                                               THREAD);
   297       // If the referenced entries already exist in *merge_cp_p, then
   298       // both new_name_ref_i and new_signature_ref_i will both be 0.
   299       // In that case, all we are appending is the current entry.
   300       if (new_name_ref_i != name_ref_i) {
   301         RC_TRACE(0x00080000,
   302           ("NameAndType entry@%d name_ref_index change: %d to %d",
   303           *merge_cp_length_p, name_ref_i, new_name_ref_i));
   304       }
   305       if (new_signature_ref_i != signature_ref_i) {
   306         RC_TRACE(0x00080000,
   307           ("NameAndType entry@%d signature_ref_index change: %d to %d",
   308           *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
   309       }
   311       (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
   312         new_name_ref_i, new_signature_ref_i);
   313       if (scratch_i != *merge_cp_length_p) {
   314         // The new entry in *merge_cp_p is at a different index than
   315         // the new entry in scratch_cp so we need to map the index values.
   316         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   317       }
   318       (*merge_cp_length_p)++;
   319     } break;
   321     // this is a double-indirect CP entry so it needs special handling
   322     case JVM_CONSTANT_Fieldref:           // fall through
   323     case JVM_CONSTANT_InterfaceMethodref: // fall through
   324     case JVM_CONSTANT_Methodref:
   325     {
   326       int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
   327       int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
   328                                                           merge_cp_p, merge_cp_length_p, THREAD);
   330       int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
   331       int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
   332                                                           merge_cp_p, merge_cp_length_p, THREAD);
   334       const char *entry_name;
   335       switch (scratch_cp->tag_at(scratch_i).value()) {
   336       case JVM_CONSTANT_Fieldref:
   337         entry_name = "Fieldref";
   338         (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
   339           new_name_and_type_ref_i);
   340         break;
   341       case JVM_CONSTANT_InterfaceMethodref:
   342         entry_name = "IFMethodref";
   343         (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
   344           new_klass_ref_i, new_name_and_type_ref_i);
   345         break;
   346       case JVM_CONSTANT_Methodref:
   347         entry_name = "Methodref";
   348         (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
   349           new_name_and_type_ref_i);
   350         break;
   351       default:
   352         guarantee(false, "bad switch");
   353         break;
   354       }
   356       if (klass_ref_i != new_klass_ref_i) {
   357         RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
   358           entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
   359       }
   360       if (name_and_type_ref_i != new_name_and_type_ref_i) {
   361         RC_TRACE(0x00080000,
   362           ("%s entry@%d name_and_type_index changed: %d to %d",
   363           entry_name, *merge_cp_length_p, name_and_type_ref_i,
   364           new_name_and_type_ref_i));
   365       }
   367       if (scratch_i != *merge_cp_length_p) {
   368         // The new entry in *merge_cp_p is at a different index than
   369         // the new entry in scratch_cp so we need to map the index values.
   370         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   371       }
   372       (*merge_cp_length_p)++;
   373     } break;
   375     // this is an indirect CP entry so it needs special handling
   376     case JVM_CONSTANT_MethodType:
   377     {
   378       int ref_i = scratch_cp->method_type_index_at(scratch_i);
   379       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
   380                                                     merge_cp_length_p, THREAD);
   381       if (new_ref_i != ref_i) {
   382         RC_TRACE(0x00080000,
   383                  ("MethodType entry@%d ref_index change: %d to %d",
   384                   *merge_cp_length_p, ref_i, new_ref_i));
   385       }
   386       (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
   387       if (scratch_i != *merge_cp_length_p) {
   388         // The new entry in *merge_cp_p is at a different index than
   389         // the new entry in scratch_cp so we need to map the index values.
   390         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   391       }
   392       (*merge_cp_length_p)++;
   393     } break;
   395     // this is an indirect CP entry so it needs special handling
   396     case JVM_CONSTANT_MethodHandle:
   397     {
   398       int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
   399       int ref_i = scratch_cp->method_handle_index_at(scratch_i);
   400       int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
   401                                                     merge_cp_length_p, THREAD);
   402       if (new_ref_i != ref_i) {
   403         RC_TRACE(0x00080000,
   404                  ("MethodHandle entry@%d ref_index change: %d to %d",
   405                   *merge_cp_length_p, ref_i, new_ref_i));
   406       }
   407       (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
   408       if (scratch_i != *merge_cp_length_p) {
   409         // The new entry in *merge_cp_p is at a different index than
   410         // the new entry in scratch_cp so we need to map the index values.
   411         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   412       }
   413       (*merge_cp_length_p)++;
   414     } break;
   416     // this is an indirect CP entry so it needs special handling
   417     case JVM_CONSTANT_InvokeDynamic:
   418     {
   419       // Index of the bootstrap specifier in the operands array
   420       int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
   421       int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
   422                                             merge_cp_length_p, THREAD);
   423       // The bootstrap method NameAndType_info index
   424       int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
   425       int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
   426                                                     merge_cp_length_p, THREAD);
   427       if (new_bs_i != old_bs_i) {
   428         RC_TRACE(0x00080000,
   429                  ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
   430                   *merge_cp_length_p, old_bs_i, new_bs_i));
   431       }
   432       if (new_ref_i != old_ref_i) {
   433         RC_TRACE(0x00080000,
   434                  ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
   435                   *merge_cp_length_p, old_ref_i, new_ref_i));
   436       }
   438       (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
   439       if (scratch_i != *merge_cp_length_p) {
   440         // The new entry in *merge_cp_p is at a different index than
   441         // the new entry in scratch_cp so we need to map the index values.
   442         map_index(scratch_cp, scratch_i, *merge_cp_length_p);
   443       }
   444       (*merge_cp_length_p)++;
   445     } break;
   447     // At this stage, Class or UnresolvedClass could be here, but not
   448     // ClassIndex
   449     case JVM_CONSTANT_ClassIndex: // fall through
   451     // Invalid is used as the tag for the second constant pool entry
   452     // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
   453     // not be seen by itself.
   454     case JVM_CONSTANT_Invalid: // fall through
   456     // At this stage, String could be here, but not StringIndex
   457     case JVM_CONSTANT_StringIndex: // fall through
   459     // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
   460     // here
   461     case JVM_CONSTANT_UnresolvedClassInError: // fall through
   463     default:
   464     {
   465       // leave a breadcrumb
   466       jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
   467       ShouldNotReachHere();
   468     } break;
   469   } // end switch tag value
   470 } // end append_entry()
   473 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
   474       int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
   476   int new_ref_i = ref_i;
   477   bool match = (ref_i < *merge_cp_length_p) &&
   478                scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
   480   if (!match) {
   481     // forward reference in *merge_cp_p or not a direct match
   482     int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
   483     if (found_i != 0) {
   484       guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
   485       // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
   486       new_ref_i = found_i;
   487       map_index(scratch_cp, ref_i, found_i);
   488     } else {
   489       // no match found so we have to append this entry to *merge_cp_p
   490       append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
   491       // The above call to append_entry() can only append one entry
   492       // so the post call query of *merge_cp_length_p is only for
   493       // the sake of consistency.
   494       new_ref_i = *merge_cp_length_p - 1;
   495     }
   496   }
   498   return new_ref_i;
   499 } // end find_or_append_indirect_entry()
   502 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
   503 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
   504 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
   505 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
   506        constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
   508   int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
   509   int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
   510                                                 merge_cp_length_p, THREAD);
   511   if (new_ref_i != old_ref_i) {
   512     RC_TRACE(0x00080000,
   513              ("operands entry@%d bootstrap method ref_index change: %d to %d",
   514               _operands_cur_length, old_ref_i, new_ref_i));
   515   }
   517   Array<u2>* merge_ops = (*merge_cp_p)->operands();
   518   int new_bs_i = _operands_cur_length;
   519   // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
   520   // However, the operand_offset_at(0) was set in the extend_operands() call.
   521   int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
   522                                  : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
   523   int argc     = scratch_cp->operand_argument_count_at(old_bs_i);
   525   ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
   526   merge_ops->at_put(new_base++, new_ref_i);
   527   merge_ops->at_put(new_base++, argc);
   529   for (int i = 0; i < argc; i++) {
   530     int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
   531     int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
   532                                                       merge_cp_length_p, THREAD);
   533     merge_ops->at_put(new_base++, new_arg_ref_i);
   534     if (new_arg_ref_i != old_arg_ref_i) {
   535       RC_TRACE(0x00080000,
   536                ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
   537                 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));
   538     }
   539   }
   540   if (old_bs_i != _operands_cur_length) {
   541     // The bootstrap specifier in *merge_cp_p is at a different index than
   542     // that in scratch_cp so we need to map the index values.
   543     map_operand_index(old_bs_i, new_bs_i);
   544   }
   545   _operands_cur_length++;
   546 } // end append_operand()
   549 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
   550       int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
   552   int new_bs_i = old_bs_i; // bootstrap specifier index
   553   bool match = (old_bs_i < _operands_cur_length) &&
   554                scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
   556   if (!match) {
   557     // forward reference in *merge_cp_p or not a direct match
   558     int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
   559                                                     _operands_cur_length, THREAD);
   560     if (found_i != -1) {
   561       guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
   562       // found a matching operand somewhere else in *merge_cp_p so just need a mapping
   563       new_bs_i = found_i;
   564       map_operand_index(old_bs_i, found_i);
   565     } else {
   566       // no match found so we have to append this bootstrap specifier to *merge_cp_p
   567       append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
   568       new_bs_i = _operands_cur_length - 1;
   569     }
   570   }
   571   return new_bs_i;
   572 } // end find_or_append_operand()
   575 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
   576   if (merge_cp->operands() == NULL) {
   577     return;
   578   }
   579   // Shrink the merge_cp operands
   580   merge_cp->shrink_operands(_operands_cur_length, CHECK);
   582   if (RC_TRACE_ENABLED(0x00040000)) {
   583     // don't want to loop unless we are tracing
   584     int count = 0;
   585     for (int i = 1; i < _operands_index_map_p->length(); i++) {
   586       int value = _operands_index_map_p->at(i);
   587       if (value != -1) {
   588         RC_TRACE_WITH_THREAD(0x00040000, THREAD,
   589           ("operands_index_map[%d]: old=%d new=%d", count, i, value));
   590         count++;
   591       }
   592     }
   593   }
   594   // Clean-up
   595   _operands_index_map_p = NULL;
   596   _operands_cur_length = 0;
   597   _operands_index_map_count = 0;
   598 } // end finalize_operands_merge()
   601 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
   602              instanceKlassHandle the_class,
   603              instanceKlassHandle scratch_class) {
   604   int i;
   606   // Check superclasses, or rather their names, since superclasses themselves can be
   607   // requested to replace.
   608   // Check for NULL superclass first since this might be java.lang.Object
   609   if (the_class->super() != scratch_class->super() &&
   610       (the_class->super() == NULL || scratch_class->super() == NULL ||
   611        the_class->super()->name() !=
   612        scratch_class->super()->name())) {
   613     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
   614   }
   616   // Check if the number, names and order of directly implemented interfaces are the same.
   617   // I think in principle we should just check if the sets of names of directly implemented
   618   // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
   619   // .java file, also changes in .class file) should not matter. However, comparing sets is
   620   // technically a bit more difficult, and, more importantly, I am not sure at present that the
   621   // order of interfaces does not matter on the implementation level, i.e. that the VM does not
   622   // rely on it somewhere.
   623   Array<Klass*>* k_interfaces = the_class->local_interfaces();
   624   Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
   625   int n_intfs = k_interfaces->length();
   626   if (n_intfs != k_new_interfaces->length()) {
   627     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
   628   }
   629   for (i = 0; i < n_intfs; i++) {
   630     if (k_interfaces->at(i)->name() !=
   631         k_new_interfaces->at(i)->name()) {
   632       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
   633     }
   634   }
   636   // Check whether class is in the error init state.
   637   if (the_class->is_in_error_state()) {
   638     // TBD #5057930: special error code is needed in 1.6
   639     return JVMTI_ERROR_INVALID_CLASS;
   640   }
   642   // Check whether class modifiers are the same.
   643   jushort old_flags = (jushort) the_class->access_flags().get_flags();
   644   jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
   645   if (old_flags != new_flags) {
   646     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
   647   }
   649   // Check if the number, names, types and order of fields declared in these classes
   650   // are the same.
   651   JavaFieldStream old_fs(the_class);
   652   JavaFieldStream new_fs(scratch_class);
   653   for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
   654     // access
   655     old_flags = old_fs.access_flags().as_short();
   656     new_flags = new_fs.access_flags().as_short();
   657     if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
   658       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
   659     }
   660     // offset
   661     if (old_fs.offset() != new_fs.offset()) {
   662       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
   663     }
   664     // name and signature
   665     Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
   666     Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
   667     Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
   668     Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
   669     if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
   670       return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
   671     }
   672   }
   674   // If both streams aren't done then we have a differing number of
   675   // fields.
   676   if (!old_fs.done() || !new_fs.done()) {
   677     return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
   678   }
   680   // Do a parallel walk through the old and new methods. Detect
   681   // cases where they match (exist in both), have been added in
   682   // the new methods, or have been deleted (exist only in the
   683   // old methods).  The class file parser places methods in order
   684   // by method name, but does not order overloaded methods by
   685   // signature.  In order to determine what fate befell the methods,
   686   // this code places the overloaded new methods that have matching
   687   // old methods in the same order as the old methods and places
   688   // new overloaded methods at the end of overloaded methods of
   689   // that name. The code for this order normalization is adapted
   690   // from the algorithm used in InstanceKlass::find_method().
   691   // Since we are swapping out of order entries as we find them,
   692   // we only have to search forward through the overloaded methods.
   693   // Methods which are added and have the same name as an existing
   694   // method (but different signature) will be put at the end of
   695   // the methods with that name, and the name mismatch code will
   696   // handle them.
   697   Array<Method*>* k_old_methods(the_class->methods());
   698   Array<Method*>* k_new_methods(scratch_class->methods());
   699   int n_old_methods = k_old_methods->length();
   700   int n_new_methods = k_new_methods->length();
   701   Thread* thread = Thread::current();
   703   int ni = 0;
   704   int oi = 0;
   705   while (true) {
   706     Method* k_old_method;
   707     Method* k_new_method;
   708     enum { matched, added, deleted, undetermined } method_was = undetermined;
   710     if (oi >= n_old_methods) {
   711       if (ni >= n_new_methods) {
   712         break; // we've looked at everything, done
   713       }
   714       // New method at the end
   715       k_new_method = k_new_methods->at(ni);
   716       method_was = added;
   717     } else if (ni >= n_new_methods) {
   718       // Old method, at the end, is deleted
   719       k_old_method = k_old_methods->at(oi);
   720       method_was = deleted;
   721     } else {
   722       // There are more methods in both the old and new lists
   723       k_old_method = k_old_methods->at(oi);
   724       k_new_method = k_new_methods->at(ni);
   725       if (k_old_method->name() != k_new_method->name()) {
   726         // Methods are sorted by method name, so a mismatch means added
   727         // or deleted
   728         if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
   729           method_was = added;
   730         } else {
   731           method_was = deleted;
   732         }
   733       } else if (k_old_method->signature() == k_new_method->signature()) {
   734         // Both the name and signature match
   735         method_was = matched;
   736       } else {
   737         // The name matches, but the signature doesn't, which means we have to
   738         // search forward through the new overloaded methods.
   739         int nj;  // outside the loop for post-loop check
   740         for (nj = ni + 1; nj < n_new_methods; nj++) {
   741           Method* m = k_new_methods->at(nj);
   742           if (k_old_method->name() != m->name()) {
   743             // reached another method name so no more overloaded methods
   744             method_was = deleted;
   745             break;
   746           }
   747           if (k_old_method->signature() == m->signature()) {
   748             // found a match so swap the methods
   749             k_new_methods->at_put(ni, m);
   750             k_new_methods->at_put(nj, k_new_method);
   751             k_new_method = m;
   752             method_was = matched;
   753             break;
   754           }
   755         }
   757         if (nj >= n_new_methods) {
   758           // reached the end without a match; so method was deleted
   759           method_was = deleted;
   760         }
   761       }
   762     }
   764     switch (method_was) {
   765     case matched:
   766       // methods match, be sure modifiers do too
   767       old_flags = (jushort) k_old_method->access_flags().get_flags();
   768       new_flags = (jushort) k_new_method->access_flags().get_flags();
   769       if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
   770         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
   771       }
   772       {
   773         u2 new_num = k_new_method->method_idnum();
   774         u2 old_num = k_old_method->method_idnum();
   775         if (new_num != old_num) {
   776           Method* idnum_owner = scratch_class->method_with_idnum(old_num);
   777           if (idnum_owner != NULL) {
   778             // There is already a method assigned this idnum -- switch them
   779             idnum_owner->set_method_idnum(new_num);
   780           }
   781           k_new_method->set_method_idnum(old_num);
   782           if (thread->has_pending_exception()) {
   783             return JVMTI_ERROR_OUT_OF_MEMORY;
   784           }
   785         }
   786       }
   787       RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
   788                             k_new_method->name_and_sig_as_C_string(), ni,
   789                             k_old_method->name_and_sig_as_C_string(), oi));
   790       // advance to next pair of methods
   791       ++oi;
   792       ++ni;
   793       break;
   794     case added:
   795       // method added, see if it is OK
   796       new_flags = (jushort) k_new_method->access_flags().get_flags();
   797       if ((new_flags & JVM_ACC_PRIVATE) == 0
   798            // hack: private should be treated as final, but alas
   799           || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
   800          ) {
   801         // new methods must be private
   802         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
   803       }
   804       {
   805         u2 num = the_class->next_method_idnum();
   806         if (num == ConstMethod::UNSET_IDNUM) {
   807           // cannot add any more methods
   808           return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
   809         }
   810         u2 new_num = k_new_method->method_idnum();
   811         Method* idnum_owner = scratch_class->method_with_idnum(num);
   812         if (idnum_owner != NULL) {
   813           // There is already a method assigned this idnum -- switch them
   814           idnum_owner->set_method_idnum(new_num);
   815         }
   816         k_new_method->set_method_idnum(num);
   817         if (thread->has_pending_exception()) {
   818           return JVMTI_ERROR_OUT_OF_MEMORY;
   819         }
   820       }
   821       RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
   822                             k_new_method->name_and_sig_as_C_string(), ni));
   823       ++ni; // advance to next new method
   824       break;
   825     case deleted:
   826       // method deleted, see if it is OK
   827       old_flags = (jushort) k_old_method->access_flags().get_flags();
   828       if ((old_flags & JVM_ACC_PRIVATE) == 0
   829            // hack: private should be treated as final, but alas
   830           || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
   831          ) {
   832         // deleted methods must be private
   833         return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
   834       }
   835       RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
   836                             k_old_method->name_and_sig_as_C_string(), oi));
   837       ++oi; // advance to next old method
   838       break;
   839     default:
   840       ShouldNotReachHere();
   841     }
   842   }
   844   return JVMTI_ERROR_NONE;
   845 }
   848 // Find new constant pool index value for old constant pool index value
   849 // by seaching the index map. Returns zero (0) if there is no mapped
   850 // value for the old constant pool index.
   851 int VM_RedefineClasses::find_new_index(int old_index) {
   852   if (_index_map_count == 0) {
   853     // map is empty so nothing can be found
   854     return 0;
   855   }
   857   if (old_index < 1 || old_index >= _index_map_p->length()) {
   858     // The old_index is out of range so it is not mapped. This should
   859     // not happen in regular constant pool merging use, but it can
   860     // happen if a corrupt annotation is processed.
   861     return 0;
   862   }
   864   int value = _index_map_p->at(old_index);
   865   if (value == -1) {
   866     // the old_index is not mapped
   867     return 0;
   868   }
   870   return value;
   871 } // end find_new_index()
   874 // Find new bootstrap specifier index value for old bootstrap specifier index
   875 // value by seaching the index map. Returns unused index (-1) if there is
   876 // no mapped value for the old bootstrap specifier index.
   877 int VM_RedefineClasses::find_new_operand_index(int old_index) {
   878   if (_operands_index_map_count == 0) {
   879     // map is empty so nothing can be found
   880     return -1;
   881   }
   883   if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
   884     // The old_index is out of range so it is not mapped.
   885     // This should not happen in regular constant pool merging use.
   886     return -1;
   887   }
   889   int value = _operands_index_map_p->at(old_index);
   890   if (value == -1) {
   891     // the old_index is not mapped
   892     return -1;
   893   }
   895   return value;
   896 } // end find_new_operand_index()
   899 // Returns true if the current mismatch is due to a resolved/unresolved
   900 // class pair. Otherwise, returns false.
   901 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
   902        int index1, constantPoolHandle cp2, int index2) {
   904   jbyte t1 = cp1->tag_at(index1).value();
   905   if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
   906     return false;  // wrong entry type; not our special case
   907   }
   909   jbyte t2 = cp2->tag_at(index2).value();
   910   if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
   911     return false;  // wrong entry type; not our special case
   912   }
   914   if (t1 == t2) {
   915     return false;  // not a mismatch; not our special case
   916   }
   918   char *s1 = cp1->klass_name_at(index1)->as_C_string();
   919   char *s2 = cp2->klass_name_at(index2)->as_C_string();
   920   if (strcmp(s1, s2) != 0) {
   921     return false;  // strings don't match; not our special case
   922   }
   924   return true;  // made it through the gauntlet; this is our special case
   925 } // end is_unresolved_class_mismatch()
   928 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
   930   // For consistency allocate memory using os::malloc wrapper.
   931   _scratch_classes = (Klass**)
   932     os::malloc(sizeof(Klass*) * _class_count, mtClass);
   933   if (_scratch_classes == NULL) {
   934     return JVMTI_ERROR_OUT_OF_MEMORY;
   935   }
   936   // Zero initialize the _scratch_classes array.
   937   for (int i = 0; i < _class_count; i++) {
   938     _scratch_classes[i] = NULL;
   939   }
   941   ResourceMark rm(THREAD);
   943   JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
   944   // state can only be NULL if the current thread is exiting which
   945   // should not happen since we're trying to do a RedefineClasses
   946   guarantee(state != NULL, "exiting thread calling load_new_class_versions");
   947   for (int i = 0; i < _class_count; i++) {
   948     // Create HandleMark so that any handles created while loading new class
   949     // versions are deleted. Constant pools are deallocated while merging
   950     // constant pools
   951     HandleMark hm(THREAD);
   953     oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
   954     // classes for primitives cannot be redefined
   955     if (!is_modifiable_class(mirror)) {
   956       return JVMTI_ERROR_UNMODIFIABLE_CLASS;
   957     }
   958     Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
   959     instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
   960     Symbol*  the_class_sym = the_class->name();
   962     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
   963     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
   964       ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
   965       the_class->external_name(), _class_load_kind,
   966       os::available_memory() >> 10));
   968     ClassFileStream st((u1*) _class_defs[i].class_bytes,
   969       _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
   971     // Parse the stream.
   972     Handle the_class_loader(THREAD, the_class->class_loader());
   973     Handle protection_domain(THREAD, the_class->protection_domain());
   974     // Set redefined class handle in JvmtiThreadState class.
   975     // This redefined class is sent to agent event handler for class file
   976     // load hook event.
   977     state->set_class_being_redefined(&the_class, _class_load_kind);
   979     Klass* k = SystemDictionary::parse_stream(the_class_sym,
   980                                                 the_class_loader,
   981                                                 protection_domain,
   982                                                 &st,
   983                                                 THREAD);
   984     // Clear class_being_redefined just to be sure.
   985     state->clear_class_being_redefined();
   987     // TODO: if this is retransform, and nothing changed we can skip it
   989     instanceKlassHandle scratch_class (THREAD, k);
   991     // Need to clean up allocated InstanceKlass if there's an error so assign
   992     // the result here. Caller deallocates all the scratch classes in case of
   993     // an error.
   994     _scratch_classes[i] = k;
   996     if (HAS_PENDING_EXCEPTION) {
   997       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
   998       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
   999       RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
  1000         ex_name->as_C_string()));
  1001       CLEAR_PENDING_EXCEPTION;
  1003       if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
  1004         return JVMTI_ERROR_UNSUPPORTED_VERSION;
  1005       } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
  1006         return JVMTI_ERROR_INVALID_CLASS_FORMAT;
  1007       } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
  1008         return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
  1009       } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
  1010         // The message will be "XXX (wrong name: YYY)"
  1011         return JVMTI_ERROR_NAMES_DONT_MATCH;
  1012       } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
  1013         return JVMTI_ERROR_OUT_OF_MEMORY;
  1014       } else {  // Just in case more exceptions can be thrown..
  1015         return JVMTI_ERROR_FAILS_VERIFICATION;
  1019     // Ensure class is linked before redefine
  1020     if (!the_class->is_linked()) {
  1021       the_class->link_class(THREAD);
  1022       if (HAS_PENDING_EXCEPTION) {
  1023         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
  1024         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
  1025         RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
  1026           ex_name->as_C_string()));
  1027         CLEAR_PENDING_EXCEPTION;
  1028         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
  1029           return JVMTI_ERROR_OUT_OF_MEMORY;
  1030         } else {
  1031           return JVMTI_ERROR_INTERNAL;
  1036     // Do the validity checks in compare_and_normalize_class_versions()
  1037     // before verifying the byte codes. By doing these checks first, we
  1038     // limit the number of functions that require redirection from
  1039     // the_class to scratch_class. In particular, we don't have to
  1040     // modify JNI GetSuperclass() and thus won't change its performance.
  1041     jvmtiError res = compare_and_normalize_class_versions(the_class,
  1042                        scratch_class);
  1043     if (res != JVMTI_ERROR_NONE) {
  1044       return res;
  1047     // verify what the caller passed us
  1049       // The bug 6214132 caused the verification to fail.
  1050       // Information about the_class and scratch_class is temporarily
  1051       // recorded into jvmtiThreadState. This data is used to redirect
  1052       // the_class to scratch_class in the JVM_* functions called by the
  1053       // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
  1054       // description.
  1055       RedefineVerifyMark rvm(&the_class, &scratch_class, state);
  1056       Verifier::verify(
  1057         scratch_class, Verifier::ThrowException, true, THREAD);
  1060     if (HAS_PENDING_EXCEPTION) {
  1061       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
  1062       // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
  1063       RC_TRACE_WITH_THREAD(0x00000002, THREAD,
  1064         ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
  1065       CLEAR_PENDING_EXCEPTION;
  1066       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
  1067         return JVMTI_ERROR_OUT_OF_MEMORY;
  1068       } else {
  1069         // tell the caller the bytecodes are bad
  1070         return JVMTI_ERROR_FAILS_VERIFICATION;
  1074     res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
  1075     if (res != JVMTI_ERROR_NONE) {
  1076       return res;
  1079     if (VerifyMergedCPBytecodes) {
  1080       // verify what we have done during constant pool merging
  1082         RedefineVerifyMark rvm(&the_class, &scratch_class, state);
  1083         Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
  1086       if (HAS_PENDING_EXCEPTION) {
  1087         Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
  1088         // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
  1089         RC_TRACE_WITH_THREAD(0x00000002, THREAD,
  1090           ("verify_byte_codes post merge-CP exception: '%s'",
  1091           ex_name->as_C_string()));
  1092         CLEAR_PENDING_EXCEPTION;
  1093         if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
  1094           return JVMTI_ERROR_OUT_OF_MEMORY;
  1095         } else {
  1096           // tell the caller that constant pool merging screwed up
  1097           return JVMTI_ERROR_INTERNAL;
  1102     Rewriter::rewrite(scratch_class, THREAD);
  1103     if (!HAS_PENDING_EXCEPTION) {
  1104       scratch_class->link_methods(THREAD);
  1106     if (HAS_PENDING_EXCEPTION) {
  1107       Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
  1108       CLEAR_PENDING_EXCEPTION;
  1109       if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
  1110         return JVMTI_ERROR_OUT_OF_MEMORY;
  1111       } else {
  1112         return JVMTI_ERROR_INTERNAL;
  1116     // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
  1117     RC_TRACE_WITH_THREAD(0x00000001, THREAD,
  1118       ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
  1119       the_class->external_name(), os::available_memory() >> 10));
  1122   return JVMTI_ERROR_NONE;
  1126 // Map old_index to new_index as needed. scratch_cp is only needed
  1127 // for RC_TRACE() calls.
  1128 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
  1129        int old_index, int new_index) {
  1130   if (find_new_index(old_index) != 0) {
  1131     // old_index is already mapped
  1132     return;
  1135   if (old_index == new_index) {
  1136     // no mapping is needed
  1137     return;
  1140   _index_map_p->at_put(old_index, new_index);
  1141   _index_map_count++;
  1143   RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
  1144     scratch_cp->tag_at(old_index).value(), old_index, new_index));
  1145 } // end map_index()
  1148 // Map old_index to new_index as needed.
  1149 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
  1150   if (find_new_operand_index(old_index) != -1) {
  1151     // old_index is already mapped
  1152     return;
  1155   if (old_index == new_index) {
  1156     // no mapping is needed
  1157     return;
  1160   _operands_index_map_p->at_put(old_index, new_index);
  1161   _operands_index_map_count++;
  1163   RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
  1164 } // end map_index()
  1167 // Merge old_cp and scratch_cp and return the results of the merge via
  1168 // merge_cp_p. The number of entries in *merge_cp_p is returned via
  1169 // merge_cp_length_p. The entries in old_cp occupy the same locations
  1170 // in *merge_cp_p. Also creates a map of indices from entries in
  1171 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
  1172 // entries are only created for entries in scratch_cp that occupy a
  1173 // different location in *merged_cp_p.
  1174 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
  1175        constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
  1176        int *merge_cp_length_p, TRAPS) {
  1178   if (merge_cp_p == NULL) {
  1179     assert(false, "caller must provide scratch constantPool");
  1180     return false; // robustness
  1182   if (merge_cp_length_p == NULL) {
  1183     assert(false, "caller must provide scratch CP length");
  1184     return false; // robustness
  1186   // Worst case we need old_cp->length() + scratch_cp()->length(),
  1187   // but the caller might be smart so make sure we have at least
  1188   // the minimum.
  1189   if ((*merge_cp_p)->length() < old_cp->length()) {
  1190     assert(false, "merge area too small");
  1191     return false; // robustness
  1194   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
  1195     ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
  1196     scratch_cp->length()));
  1199     // Pass 0:
  1200     // The old_cp is copied to *merge_cp_p; this means that any code
  1201     // using old_cp does not have to change. This work looks like a
  1202     // perfect fit for ConstantPool*::copy_cp_to(), but we need to
  1203     // handle one special case:
  1204     // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
  1205     // This will make verification happy.
  1207     int old_i;  // index into old_cp
  1209     // index zero (0) is not used in constantPools
  1210     for (old_i = 1; old_i < old_cp->length(); old_i++) {
  1211       // leave debugging crumb
  1212       jbyte old_tag = old_cp->tag_at(old_i).value();
  1213       switch (old_tag) {
  1214       case JVM_CONSTANT_Class:
  1215       case JVM_CONSTANT_UnresolvedClass:
  1216         // revert the copy to JVM_CONSTANT_UnresolvedClass
  1217         // May be resolving while calling this so do the same for
  1218         // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
  1219         (*merge_cp_p)->unresolved_klass_at_put(old_i,
  1220           old_cp->klass_name_at(old_i));
  1221         break;
  1223       case JVM_CONSTANT_Double:
  1224       case JVM_CONSTANT_Long:
  1225         // just copy the entry to *merge_cp_p, but double and long take
  1226         // two constant pool entries
  1227         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
  1228         old_i++;
  1229         break;
  1231       default:
  1232         // just copy the entry to *merge_cp_p
  1233         ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
  1234         break;
  1236     } // end for each old_cp entry
  1238     ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
  1239     (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
  1241     // We don't need to sanity check that *merge_cp_length_p is within
  1242     // *merge_cp_p bounds since we have the minimum on-entry check above.
  1243     (*merge_cp_length_p) = old_i;
  1246   // merge_cp_len should be the same as old_cp->length() at this point
  1247   // so this trace message is really a "warm-and-breathing" message.
  1248   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
  1249     ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
  1251   int scratch_i;  // index into scratch_cp
  1253     // Pass 1a:
  1254     // Compare scratch_cp entries to the old_cp entries that we have
  1255     // already copied to *merge_cp_p. In this pass, we are eliminating
  1256     // exact duplicates (matching entry at same index) so we only
  1257     // compare entries in the common indice range.
  1258     int increment = 1;
  1259     int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
  1260     for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
  1261       switch (scratch_cp->tag_at(scratch_i).value()) {
  1262       case JVM_CONSTANT_Double:
  1263       case JVM_CONSTANT_Long:
  1264         // double and long take two constant pool entries
  1265         increment = 2;
  1266         break;
  1268       default:
  1269         increment = 1;
  1270         break;
  1273       bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
  1274         scratch_i, CHECK_0);
  1275       if (match) {
  1276         // found a match at the same index so nothing more to do
  1277         continue;
  1278       } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
  1279                                               *merge_cp_p, scratch_i)) {
  1280         // The mismatch in compare_entry_to() above is because of a
  1281         // resolved versus unresolved class entry at the same index
  1282         // with the same string value. Since Pass 0 reverted any
  1283         // class entries to unresolved class entries in *merge_cp_p,
  1284         // we go with the unresolved class entry.
  1285         continue;
  1288       int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
  1289         CHECK_0);
  1290       if (found_i != 0) {
  1291         guarantee(found_i != scratch_i,
  1292           "compare_entry_to() and find_matching_entry() do not agree");
  1294         // Found a matching entry somewhere else in *merge_cp_p so
  1295         // just need a mapping entry.
  1296         map_index(scratch_cp, scratch_i, found_i);
  1297         continue;
  1300       // The find_matching_entry() call above could fail to find a match
  1301       // due to a resolved versus unresolved class or string entry situation
  1302       // like we solved above with the is_unresolved_*_mismatch() calls.
  1303       // However, we would have to call is_unresolved_*_mismatch() over
  1304       // all of *merge_cp_p (potentially) and that doesn't seem to be
  1305       // worth the time.
  1307       // No match found so we have to append this entry and any unique
  1308       // referenced entries to *merge_cp_p.
  1309       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
  1310         CHECK_0);
  1314   RC_TRACE_WITH_THREAD(0x00020000, THREAD,
  1315     ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
  1316     *merge_cp_length_p, scratch_i, _index_map_count));
  1318   if (scratch_i < scratch_cp->length()) {
  1319     // Pass 1b:
  1320     // old_cp is smaller than scratch_cp so there are entries in
  1321     // scratch_cp that we have not yet processed. We take care of
  1322     // those now.
  1323     int increment = 1;
  1324     for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
  1325       switch (scratch_cp->tag_at(scratch_i).value()) {
  1326       case JVM_CONSTANT_Double:
  1327       case JVM_CONSTANT_Long:
  1328         // double and long take two constant pool entries
  1329         increment = 2;
  1330         break;
  1332       default:
  1333         increment = 1;
  1334         break;
  1337       int found_i =
  1338         scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
  1339       if (found_i != 0) {
  1340         // Found a matching entry somewhere else in *merge_cp_p so
  1341         // just need a mapping entry.
  1342         map_index(scratch_cp, scratch_i, found_i);
  1343         continue;
  1346       // No match found so we have to append this entry and any unique
  1347       // referenced entries to *merge_cp_p.
  1348       append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
  1349         CHECK_0);
  1352     finalize_operands_merge(*merge_cp_p, THREAD);
  1354     RC_TRACE_WITH_THREAD(0x00020000, THREAD,
  1355       ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
  1356       *merge_cp_length_p, scratch_i, _index_map_count));
  1359   return true;
  1360 } // end merge_constant_pools()
  1363 // Scoped object to clean up the constant pool(s) created for merging
  1364 class MergeCPCleaner {
  1365   ClassLoaderData*   _loader_data;
  1366   ConstantPool*      _cp;
  1367   ConstantPool*      _scratch_cp;
  1368  public:
  1369   MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
  1370                  _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
  1371   ~MergeCPCleaner() {
  1372     _loader_data->add_to_deallocate_list(_cp);
  1373     if (_scratch_cp != NULL) {
  1374       _loader_data->add_to_deallocate_list(_scratch_cp);
  1377   void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
  1378 };
  1380 // Merge constant pools between the_class and scratch_class and
  1381 // potentially rewrite bytecodes in scratch_class to use the merged
  1382 // constant pool.
  1383 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
  1384              instanceKlassHandle the_class, instanceKlassHandle scratch_class,
  1385              TRAPS) {
  1386   // worst case merged constant pool length is old and new combined
  1387   int merge_cp_length = the_class->constants()->length()
  1388         + scratch_class->constants()->length();
  1390   // Constant pools are not easily reused so we allocate a new one
  1391   // each time.
  1392   // merge_cp is created unsafe for concurrent GC processing.  It
  1393   // should be marked safe before discarding it. Even though
  1394   // garbage,  if it crosses a card boundary, it may be scanned
  1395   // in order to find the start of the first complete object on the card.
  1396   ClassLoaderData* loader_data = the_class->class_loader_data();
  1397   ConstantPool* merge_cp_oop =
  1398     ConstantPool::allocate(loader_data,
  1399                                   merge_cp_length,
  1400                                   THREAD);
  1401   MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
  1403   HandleMark hm(THREAD);  // make sure handles are cleared before
  1404                           // MergeCPCleaner clears out merge_cp_oop
  1405   constantPoolHandle merge_cp(THREAD, merge_cp_oop);
  1407   // Get constants() from the old class because it could have been rewritten
  1408   // while we were at a safepoint allocating a new constant pool.
  1409   constantPoolHandle old_cp(THREAD, the_class->constants());
  1410   constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
  1412   // If the length changed, the class was redefined out from under us. Return
  1413   // an error.
  1414   if (merge_cp_length != the_class->constants()->length()
  1415          + scratch_class->constants()->length()) {
  1416     return JVMTI_ERROR_INTERNAL;
  1419   // Update the version number of the constant pool
  1420   merge_cp->increment_and_save_version(old_cp->version());
  1422   ResourceMark rm(THREAD);
  1423   _index_map_count = 0;
  1424   _index_map_p = new intArray(scratch_cp->length(), -1);
  1426   _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
  1427   _operands_index_map_count = 0;
  1428   _operands_index_map_p = new intArray(
  1429     ConstantPool::operand_array_length(scratch_cp->operands()), -1);
  1431   // reference to the cp holder is needed for copy_operands()
  1432   merge_cp->set_pool_holder(scratch_class());
  1433   bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
  1434                   &merge_cp_length, THREAD);
  1435   merge_cp->set_pool_holder(NULL);
  1437   if (!result) {
  1438     // The merge can fail due to memory allocation failure or due
  1439     // to robustness checks.
  1440     return JVMTI_ERROR_INTERNAL;
  1443   RC_TRACE_WITH_THREAD(0x00010000, THREAD,
  1444     ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
  1446   if (_index_map_count == 0) {
  1447     // there is nothing to map between the new and merged constant pools
  1449     if (old_cp->length() == scratch_cp->length()) {
  1450       // The old and new constant pools are the same length and the
  1451       // index map is empty. This means that the three constant pools
  1452       // are equivalent (but not the same). Unfortunately, the new
  1453       // constant pool has not gone through link resolution nor have
  1454       // the new class bytecodes gone through constant pool cache
  1455       // rewriting so we can't use the old constant pool with the new
  1456       // class.
  1458       // toss the merged constant pool at return
  1459     } else if (old_cp->length() < scratch_cp->length()) {
  1460       // The old constant pool has fewer entries than the new constant
  1461       // pool and the index map is empty. This means the new constant
  1462       // pool is a superset of the old constant pool. However, the old
  1463       // class bytecodes have already gone through constant pool cache
  1464       // rewriting so we can't use the new constant pool with the old
  1465       // class.
  1467       // toss the merged constant pool at return
  1468     } else {
  1469       // The old constant pool has more entries than the new constant
  1470       // pool and the index map is empty. This means that both the old
  1471       // and merged constant pools are supersets of the new constant
  1472       // pool.
  1474       // Replace the new constant pool with a shrunken copy of the
  1475       // merged constant pool
  1476       set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, THREAD);
  1477       // The new constant pool replaces scratch_cp so have cleaner clean it up.
  1478       // It can't be cleaned up while there are handles to it.
  1479       cp_cleaner.add_scratch_cp(scratch_cp());
  1481   } else {
  1482     if (RC_TRACE_ENABLED(0x00040000)) {
  1483       // don't want to loop unless we are tracing
  1484       int count = 0;
  1485       for (int i = 1; i < _index_map_p->length(); i++) {
  1486         int value = _index_map_p->at(i);
  1488         if (value != -1) {
  1489           RC_TRACE_WITH_THREAD(0x00040000, THREAD,
  1490             ("index_map[%d]: old=%d new=%d", count, i, value));
  1491           count++;
  1496     // We have entries mapped between the new and merged constant pools
  1497     // so we have to rewrite some constant pool references.
  1498     if (!rewrite_cp_refs(scratch_class, THREAD)) {
  1499       return JVMTI_ERROR_INTERNAL;
  1502     // Replace the new constant pool with a shrunken copy of the
  1503     // merged constant pool so now the rewritten bytecodes have
  1504     // valid references; the previous new constant pool will get
  1505     // GCed.
  1506     set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, THREAD);
  1507     // The new constant pool replaces scratch_cp so have cleaner clean it up.
  1508     // It can't be cleaned up while there are handles to it.
  1509     cp_cleaner.add_scratch_cp(scratch_cp());
  1512   return JVMTI_ERROR_NONE;
  1513 } // end merge_cp_and_rewrite()
  1516 // Rewrite constant pool references in klass scratch_class.
  1517 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
  1518        TRAPS) {
  1520   // rewrite constant pool references in the methods:
  1521   if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
  1522     // propagate failure back to caller
  1523     return false;
  1526   // rewrite constant pool references in the class_annotations:
  1527   if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
  1528     // propagate failure back to caller
  1529     return false;
  1532   // rewrite constant pool references in the fields_annotations:
  1533   if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
  1534     // propagate failure back to caller
  1535     return false;
  1538   // rewrite constant pool references in the methods_annotations:
  1539   if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
  1540     // propagate failure back to caller
  1541     return false;
  1544   // rewrite constant pool references in the methods_parameter_annotations:
  1545   if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
  1546          THREAD)) {
  1547     // propagate failure back to caller
  1548     return false;
  1551   // rewrite constant pool references in the methods_default_annotations:
  1552   if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
  1553          THREAD)) {
  1554     // propagate failure back to caller
  1555     return false;
  1558   return true;
  1559 } // end rewrite_cp_refs()
  1561 // Rewrite constant pool references in the methods.
  1562 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
  1563        instanceKlassHandle scratch_class, TRAPS) {
  1565   Array<Method*>* methods = scratch_class->methods();
  1567   if (methods == NULL || methods->length() == 0) {
  1568     // no methods so nothing to do
  1569     return true;
  1572   // rewrite constant pool references in the methods:
  1573   for (int i = methods->length() - 1; i >= 0; i--) {
  1574     methodHandle method(THREAD, methods->at(i));
  1575     methodHandle new_method;
  1576     rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
  1577     if (!new_method.is_null()) {
  1578       // the method has been replaced so save the new method version
  1579       methods->at_put(i, new_method());
  1583   return true;
  1587 // Rewrite constant pool references in the specific method. This code
  1588 // was adapted from Rewriter::rewrite_method().
  1589 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
  1590        methodHandle *new_method_p, TRAPS) {
  1592   *new_method_p = methodHandle();  // default is no new method
  1594   // We cache a pointer to the bytecodes here in code_base. If GC
  1595   // moves the Method*, then the bytecodes will also move which
  1596   // will likely cause a crash. We create a No_Safepoint_Verifier
  1597   // object to detect whether we pass a possible safepoint in this
  1598   // code block.
  1599   No_Safepoint_Verifier nsv;
  1601   // Bytecodes and their length
  1602   address code_base = method->code_base();
  1603   int code_length = method->code_size();
  1605   int bc_length;
  1606   for (int bci = 0; bci < code_length; bci += bc_length) {
  1607     address bcp = code_base + bci;
  1608     Bytecodes::Code c = (Bytecodes::Code)(*bcp);
  1610     bc_length = Bytecodes::length_for(c);
  1611     if (bc_length == 0) {
  1612       // More complicated bytecodes report a length of zero so
  1613       // we have to try again a slightly different way.
  1614       bc_length = Bytecodes::length_at(method(), bcp);
  1617     assert(bc_length != 0, "impossible bytecode length");
  1619     switch (c) {
  1620       case Bytecodes::_ldc:
  1622         int cp_index = *(bcp + 1);
  1623         int new_index = find_new_index(cp_index);
  1625         if (StressLdcRewrite && new_index == 0) {
  1626           // If we are stressing ldc -> ldc_w rewriting, then we
  1627           // always need a new_index value.
  1628           new_index = cp_index;
  1630         if (new_index != 0) {
  1631           // the original index is mapped so we have more work to do
  1632           if (!StressLdcRewrite && new_index <= max_jubyte) {
  1633             // The new value can still use ldc instead of ldc_w
  1634             // unless we are trying to stress ldc -> ldc_w rewriting
  1635             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  1636               ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
  1637               bcp, cp_index, new_index));
  1638             *(bcp + 1) = new_index;
  1639           } else {
  1640             RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  1641               ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
  1642               Bytecodes::name(c), bcp, cp_index, new_index));
  1643             // the new value needs ldc_w instead of ldc
  1644             u_char inst_buffer[4]; // max instruction size is 4 bytes
  1645             bcp = (address)inst_buffer;
  1646             // construct new instruction sequence
  1647             *bcp = Bytecodes::_ldc_w;
  1648             bcp++;
  1649             // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
  1650             // See comment below for difference between put_Java_u2()
  1651             // and put_native_u2().
  1652             Bytes::put_Java_u2(bcp, new_index);
  1654             Relocator rc(method, NULL /* no RelocatorListener needed */);
  1655             methodHandle m;
  1657               Pause_No_Safepoint_Verifier pnsv(&nsv);
  1659               // ldc is 2 bytes and ldc_w is 3 bytes
  1660               m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
  1661               if (m.is_null() || HAS_PENDING_EXCEPTION) {
  1662                 guarantee(false, "insert_space_at() failed");
  1666             // return the new method so that the caller can update
  1667             // the containing class
  1668             *new_method_p = method = m;
  1669             // switch our bytecode processing loop from the old method
  1670             // to the new method
  1671             code_base = method->code_base();
  1672             code_length = method->code_size();
  1673             bcp = code_base + bci;
  1674             c = (Bytecodes::Code)(*bcp);
  1675             bc_length = Bytecodes::length_for(c);
  1676             assert(bc_length != 0, "sanity check");
  1677           } // end we need ldc_w instead of ldc
  1678         } // end if there is a mapped index
  1679       } break;
  1681       // these bytecodes have a two-byte constant pool index
  1682       case Bytecodes::_anewarray      : // fall through
  1683       case Bytecodes::_checkcast      : // fall through
  1684       case Bytecodes::_getfield       : // fall through
  1685       case Bytecodes::_getstatic      : // fall through
  1686       case Bytecodes::_instanceof     : // fall through
  1687       case Bytecodes::_invokedynamic  : // fall through
  1688       case Bytecodes::_invokeinterface: // fall through
  1689       case Bytecodes::_invokespecial  : // fall through
  1690       case Bytecodes::_invokestatic   : // fall through
  1691       case Bytecodes::_invokevirtual  : // fall through
  1692       case Bytecodes::_ldc_w          : // fall through
  1693       case Bytecodes::_ldc2_w         : // fall through
  1694       case Bytecodes::_multianewarray : // fall through
  1695       case Bytecodes::_new            : // fall through
  1696       case Bytecodes::_putfield       : // fall through
  1697       case Bytecodes::_putstatic      :
  1699         address p = bcp + 1;
  1700         int cp_index = Bytes::get_Java_u2(p);
  1701         int new_index = find_new_index(cp_index);
  1702         if (new_index != 0) {
  1703           // the original index is mapped so update w/ new value
  1704           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  1705             ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
  1706             bcp, cp_index, new_index));
  1707           // Rewriter::rewrite_method() uses put_native_u2() in this
  1708           // situation because it is reusing the constant pool index
  1709           // location for a native index into the ConstantPoolCache.
  1710           // Since we are updating the constant pool index prior to
  1711           // verification and ConstantPoolCache initialization, we
  1712           // need to keep the new index in Java byte order.
  1713           Bytes::put_Java_u2(p, new_index);
  1715       } break;
  1717   } // end for each bytecode
  1719   // We also need to rewrite the parameter name indexes, if there is
  1720   // method parameter data present
  1721   if(method->has_method_parameters()) {
  1722     const int len = method->method_parameters_length();
  1723     MethodParametersElement* elem = method->method_parameters_start();
  1725     for (int i = 0; i < len; i++) {
  1726       const u2 cp_index = elem[i].name_cp_index;
  1727       elem[i].name_cp_index = find_new_index(cp_index);
  1730 } // end rewrite_cp_refs_in_method()
  1733 // Rewrite constant pool references in the class_annotations field.
  1734 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
  1735        instanceKlassHandle scratch_class, TRAPS) {
  1737   AnnotationArray* class_annotations = scratch_class->class_annotations();
  1738   if (class_annotations == NULL || class_annotations->length() == 0) {
  1739     // no class_annotations so nothing to do
  1740     return true;
  1743   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1744     ("class_annotations length=%d", class_annotations->length()));
  1746   int byte_i = 0;  // byte index into class_annotations
  1747   return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
  1748            THREAD);
  1752 // Rewrite constant pool references in an annotations typeArray. This
  1753 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
  1754 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
  1755 //
  1756 // annotations_typeArray {
  1757 //   u2 num_annotations;
  1758 //   annotation annotations[num_annotations];
  1759 // }
  1760 //
  1761 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
  1762        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
  1764   if ((byte_i_ref + 2) > annotations_typeArray->length()) {
  1765     // not enough room for num_annotations field
  1766     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1767       ("length() is too small for num_annotations field"));
  1768     return false;
  1771   u2 num_annotations = Bytes::get_Java_u2((address)
  1772                          annotations_typeArray->adr_at(byte_i_ref));
  1773   byte_i_ref += 2;
  1775   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1776     ("num_annotations=%d", num_annotations));
  1778   int calc_num_annotations = 0;
  1779   for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
  1780     if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
  1781            byte_i_ref, THREAD)) {
  1782       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1783         ("bad annotation_struct at %d", calc_num_annotations));
  1784       // propagate failure back to caller
  1785       return false;
  1788   assert(num_annotations == calc_num_annotations, "sanity check");
  1790   return true;
  1791 } // end rewrite_cp_refs_in_annotations_typeArray()
  1794 // Rewrite constant pool references in the annotation struct portion of
  1795 // an annotations_typeArray. This "structure" is from section 4.8.15 of
  1796 // the 2nd-edition of the VM spec:
  1797 //
  1798 // struct annotation {
  1799 //   u2 type_index;
  1800 //   u2 num_element_value_pairs;
  1801 //   {
  1802 //     u2 element_name_index;
  1803 //     element_value value;
  1804 //   } element_value_pairs[num_element_value_pairs];
  1805 // }
  1806 //
  1807 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
  1808        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
  1809   if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
  1810     // not enough room for smallest annotation_struct
  1811     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1812       ("length() is too small for annotation_struct"));
  1813     return false;
  1816   u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
  1817                     byte_i_ref, "mapped old type_index=%d", THREAD);
  1819   u2 num_element_value_pairs = Bytes::get_Java_u2((address)
  1820                                  annotations_typeArray->adr_at(byte_i_ref));
  1821   byte_i_ref += 2;
  1823   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1824     ("type_index=%d  num_element_value_pairs=%d", type_index,
  1825     num_element_value_pairs));
  1827   int calc_num_element_value_pairs = 0;
  1828   for (; calc_num_element_value_pairs < num_element_value_pairs;
  1829        calc_num_element_value_pairs++) {
  1830     if ((byte_i_ref + 2) > annotations_typeArray->length()) {
  1831       // not enough room for another element_name_index, let alone
  1832       // the rest of another component
  1833       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1834         ("length() is too small for element_name_index"));
  1835       return false;
  1838     u2 element_name_index = rewrite_cp_ref_in_annotation_data(
  1839                               annotations_typeArray, byte_i_ref,
  1840                               "mapped old element_name_index=%d", THREAD);
  1842     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1843       ("element_name_index=%d", element_name_index));
  1845     if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
  1846            byte_i_ref, THREAD)) {
  1847       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1848         ("bad element_value at %d", calc_num_element_value_pairs));
  1849       // propagate failure back to caller
  1850       return false;
  1852   } // end for each component
  1853   assert(num_element_value_pairs == calc_num_element_value_pairs,
  1854     "sanity check");
  1856   return true;
  1857 } // end rewrite_cp_refs_in_annotation_struct()
  1860 // Rewrite a constant pool reference at the current position in
  1861 // annotations_typeArray if needed. Returns the original constant
  1862 // pool reference if a rewrite was not needed or the new constant
  1863 // pool reference if a rewrite was needed.
  1864 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
  1865      AnnotationArray* annotations_typeArray, int &byte_i_ref,
  1866      const char * trace_mesg, TRAPS) {
  1868   address cp_index_addr = (address)
  1869     annotations_typeArray->adr_at(byte_i_ref);
  1870   u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
  1871   u2 new_cp_index = find_new_index(old_cp_index);
  1872   if (new_cp_index != 0) {
  1873     RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
  1874     Bytes::put_Java_u2(cp_index_addr, new_cp_index);
  1875     old_cp_index = new_cp_index;
  1877   byte_i_ref += 2;
  1878   return old_cp_index;
  1882 // Rewrite constant pool references in the element_value portion of an
  1883 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
  1884 // the 2nd-edition of the VM spec:
  1885 //
  1886 // struct element_value {
  1887 //   u1 tag;
  1888 //   union {
  1889 //     u2 const_value_index;
  1890 //     {
  1891 //       u2 type_name_index;
  1892 //       u2 const_name_index;
  1893 //     } enum_const_value;
  1894 //     u2 class_info_index;
  1895 //     annotation annotation_value;
  1896 //     struct {
  1897 //       u2 num_values;
  1898 //       element_value values[num_values];
  1899 //     } array_value;
  1900 //   } value;
  1901 // }
  1902 //
  1903 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
  1904        AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
  1906   if ((byte_i_ref + 1) > annotations_typeArray->length()) {
  1907     // not enough room for a tag let alone the rest of an element_value
  1908     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1909       ("length() is too small for a tag"));
  1910     return false;
  1913   u1 tag = annotations_typeArray->at(byte_i_ref);
  1914   byte_i_ref++;
  1915   RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
  1917   switch (tag) {
  1918     // These BaseType tag values are from Table 4.2 in VM spec:
  1919     case 'B':  // byte
  1920     case 'C':  // char
  1921     case 'D':  // double
  1922     case 'F':  // float
  1923     case 'I':  // int
  1924     case 'J':  // long
  1925     case 'S':  // short
  1926     case 'Z':  // boolean
  1928     // The remaining tag values are from Table 4.8 in the 2nd-edition of
  1929     // the VM spec:
  1930     case 's':
  1932       // For the above tag values (including the BaseType values),
  1933       // value.const_value_index is right union field.
  1935       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
  1936         // not enough room for a const_value_index
  1937         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1938           ("length() is too small for a const_value_index"));
  1939         return false;
  1942       u2 const_value_index = rewrite_cp_ref_in_annotation_data(
  1943                                annotations_typeArray, byte_i_ref,
  1944                                "mapped old const_value_index=%d", THREAD);
  1946       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1947         ("const_value_index=%d", const_value_index));
  1948     } break;
  1950     case 'e':
  1952       // for the above tag value, value.enum_const_value is right union field
  1954       if ((byte_i_ref + 4) > annotations_typeArray->length()) {
  1955         // not enough room for a enum_const_value
  1956         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1957           ("length() is too small for a enum_const_value"));
  1958         return false;
  1961       u2 type_name_index = rewrite_cp_ref_in_annotation_data(
  1962                              annotations_typeArray, byte_i_ref,
  1963                              "mapped old type_name_index=%d", THREAD);
  1965       u2 const_name_index = rewrite_cp_ref_in_annotation_data(
  1966                               annotations_typeArray, byte_i_ref,
  1967                               "mapped old const_name_index=%d", THREAD);
  1969       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1970         ("type_name_index=%d  const_name_index=%d", type_name_index,
  1971         const_name_index));
  1972     } break;
  1974     case 'c':
  1976       // for the above tag value, value.class_info_index is right union field
  1978       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
  1979         // not enough room for a class_info_index
  1980         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1981           ("length() is too small for a class_info_index"));
  1982         return false;
  1985       u2 class_info_index = rewrite_cp_ref_in_annotation_data(
  1986                               annotations_typeArray, byte_i_ref,
  1987                               "mapped old class_info_index=%d", THREAD);
  1989       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  1990         ("class_info_index=%d", class_info_index));
  1991     } break;
  1993     case '@':
  1994       // For the above tag value, value.attr_value is the right union
  1995       // field. This is a nested annotation.
  1996       if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
  1997              byte_i_ref, THREAD)) {
  1998         // propagate failure back to caller
  1999         return false;
  2001       break;
  2003     case '[':
  2005       if ((byte_i_ref + 2) > annotations_typeArray->length()) {
  2006         // not enough room for a num_values field
  2007         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2008           ("length() is too small for a num_values field"));
  2009         return false;
  2012       // For the above tag value, value.array_value is the right union
  2013       // field. This is an array of nested element_value.
  2014       u2 num_values = Bytes::get_Java_u2((address)
  2015                         annotations_typeArray->adr_at(byte_i_ref));
  2016       byte_i_ref += 2;
  2017       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
  2019       int calc_num_values = 0;
  2020       for (; calc_num_values < num_values; calc_num_values++) {
  2021         if (!rewrite_cp_refs_in_element_value(
  2022                annotations_typeArray, byte_i_ref, THREAD)) {
  2023           RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2024             ("bad nested element_value at %d", calc_num_values));
  2025           // propagate failure back to caller
  2026           return false;
  2029       assert(num_values == calc_num_values, "sanity check");
  2030     } break;
  2032     default:
  2033       RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
  2034       return false;
  2035   } // end decode tag field
  2037   return true;
  2038 } // end rewrite_cp_refs_in_element_value()
  2041 // Rewrite constant pool references in a fields_annotations field.
  2042 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
  2043        instanceKlassHandle scratch_class, TRAPS) {
  2045   Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
  2047   if (fields_annotations == NULL || fields_annotations->length() == 0) {
  2048     // no fields_annotations so nothing to do
  2049     return true;
  2052   RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2053     ("fields_annotations length=%d", fields_annotations->length()));
  2055   for (int i = 0; i < fields_annotations->length(); i++) {
  2056     AnnotationArray* field_annotations = fields_annotations->at(i);
  2057     if (field_annotations == NULL || field_annotations->length() == 0) {
  2058       // this field does not have any annotations so skip it
  2059       continue;
  2062     int byte_i = 0;  // byte index into field_annotations
  2063     if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
  2064            THREAD)) {
  2065       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2066         ("bad field_annotations at %d", i));
  2067       // propagate failure back to caller
  2068       return false;
  2072   return true;
  2073 } // end rewrite_cp_refs_in_fields_annotations()
  2076 // Rewrite constant pool references in a methods_annotations field.
  2077 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
  2078        instanceKlassHandle scratch_class, TRAPS) {
  2080   for (int i = 0; i < scratch_class->methods()->length(); i++) {
  2081     Method* m = scratch_class->methods()->at(i);
  2082     AnnotationArray* method_annotations = m->constMethod()->method_annotations();
  2084     if (method_annotations == NULL || method_annotations->length() == 0) {
  2085       // this method does not have any annotations so skip it
  2086       continue;
  2089     int byte_i = 0;  // byte index into method_annotations
  2090     if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
  2091            THREAD)) {
  2092       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2093         ("bad method_annotations at %d", i));
  2094       // propagate failure back to caller
  2095       return false;
  2099   return true;
  2100 } // end rewrite_cp_refs_in_methods_annotations()
  2103 // Rewrite constant pool references in a methods_parameter_annotations
  2104 // field. This "structure" is adapted from the
  2105 // RuntimeVisibleParameterAnnotations_attribute described in section
  2106 // 4.8.17 of the 2nd-edition of the VM spec:
  2107 //
  2108 // methods_parameter_annotations_typeArray {
  2109 //   u1 num_parameters;
  2110 //   {
  2111 //     u2 num_annotations;
  2112 //     annotation annotations[num_annotations];
  2113 //   } parameter_annotations[num_parameters];
  2114 // }
  2115 //
  2116 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
  2117        instanceKlassHandle scratch_class, TRAPS) {
  2119   for (int i = 0; i < scratch_class->methods()->length(); i++) {
  2120     Method* m = scratch_class->methods()->at(i);
  2121     AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
  2122     if (method_parameter_annotations == NULL
  2123         || method_parameter_annotations->length() == 0) {
  2124       // this method does not have any parameter annotations so skip it
  2125       continue;
  2128     if (method_parameter_annotations->length() < 1) {
  2129       // not enough room for a num_parameters field
  2130       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2131         ("length() is too small for a num_parameters field at %d", i));
  2132       return false;
  2135     int byte_i = 0;  // byte index into method_parameter_annotations
  2137     u1 num_parameters = method_parameter_annotations->at(byte_i);
  2138     byte_i++;
  2140     RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2141       ("num_parameters=%d", num_parameters));
  2143     int calc_num_parameters = 0;
  2144     for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
  2145       if (!rewrite_cp_refs_in_annotations_typeArray(
  2146              method_parameter_annotations, byte_i, THREAD)) {
  2147         RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2148           ("bad method_parameter_annotations at %d", calc_num_parameters));
  2149         // propagate failure back to caller
  2150         return false;
  2153     assert(num_parameters == calc_num_parameters, "sanity check");
  2156   return true;
  2157 } // end rewrite_cp_refs_in_methods_parameter_annotations()
  2160 // Rewrite constant pool references in a methods_default_annotations
  2161 // field. This "structure" is adapted from the AnnotationDefault_attribute
  2162 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
  2163 //
  2164 // methods_default_annotations_typeArray {
  2165 //   element_value default_value;
  2166 // }
  2167 //
  2168 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
  2169        instanceKlassHandle scratch_class, TRAPS) {
  2171   for (int i = 0; i < scratch_class->methods()->length(); i++) {
  2172     Method* m = scratch_class->methods()->at(i);
  2173     AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
  2174     if (method_default_annotations == NULL
  2175         || method_default_annotations->length() == 0) {
  2176       // this method does not have any default annotations so skip it
  2177       continue;
  2180     int byte_i = 0;  // byte index into method_default_annotations
  2182     if (!rewrite_cp_refs_in_element_value(
  2183            method_default_annotations, byte_i, THREAD)) {
  2184       RC_TRACE_WITH_THREAD(0x02000000, THREAD,
  2185         ("bad default element_value at %d", i));
  2186       // propagate failure back to caller
  2187       return false;
  2191   return true;
  2192 } // end rewrite_cp_refs_in_methods_default_annotations()
  2195 // Rewrite constant pool references in the method's stackmap table.
  2196 // These "structures" are adapted from the StackMapTable_attribute that
  2197 // is described in section 4.8.4 of the 6.0 version of the VM spec
  2198 // (dated 2005.10.26):
  2199 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
  2200 //
  2201 // stack_map {
  2202 //   u2 number_of_entries;
  2203 //   stack_map_frame entries[number_of_entries];
  2204 // }
  2205 //
  2206 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
  2207        methodHandle method, TRAPS) {
  2209   if (!method->has_stackmap_table()) {
  2210     return;
  2213   AnnotationArray* stackmap_data = method->stackmap_data();
  2214   address stackmap_p = (address)stackmap_data->adr_at(0);
  2215   address stackmap_end = stackmap_p + stackmap_data->length();
  2217   assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
  2218   u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
  2219   stackmap_p += 2;
  2221   RC_TRACE_WITH_THREAD(0x04000000, THREAD,
  2222     ("number_of_entries=%u", number_of_entries));
  2224   // walk through each stack_map_frame
  2225   u2 calc_number_of_entries = 0;
  2226   for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
  2227     // The stack_map_frame structure is a u1 frame_type followed by
  2228     // 0 or more bytes of data:
  2229     //
  2230     // union stack_map_frame {
  2231     //   same_frame;
  2232     //   same_locals_1_stack_item_frame;
  2233     //   same_locals_1_stack_item_frame_extended;
  2234     //   chop_frame;
  2235     //   same_frame_extended;
  2236     //   append_frame;
  2237     //   full_frame;
  2238     // }
  2240     assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
  2241     // The Linux compiler does not like frame_type to be u1 or u2. It
  2242     // issues the following warning for the first if-statement below:
  2243     //
  2244     // "warning: comparison is always true due to limited range of data type"
  2245     //
  2246     u4 frame_type = *stackmap_p;
  2247     stackmap_p++;
  2249     // same_frame {
  2250     //   u1 frame_type = SAME; /* 0-63 */
  2251     // }
  2252     if (frame_type >= 0 && frame_type <= 63) {
  2253       // nothing more to do for same_frame
  2256     // same_locals_1_stack_item_frame {
  2257     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
  2258     //   verification_type_info stack[1];
  2259     // }
  2260     else if (frame_type >= 64 && frame_type <= 127) {
  2261       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
  2262         calc_number_of_entries, frame_type, THREAD);
  2265     // reserved for future use
  2266     else if (frame_type >= 128 && frame_type <= 246) {
  2267       // nothing more to do for reserved frame_types
  2270     // same_locals_1_stack_item_frame_extended {
  2271     //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
  2272     //   u2 offset_delta;
  2273     //   verification_type_info stack[1];
  2274     // }
  2275     else if (frame_type == 247) {
  2276       stackmap_p += 2;
  2277       rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
  2278         calc_number_of_entries, frame_type, THREAD);
  2281     // chop_frame {
  2282     //   u1 frame_type = CHOP; /* 248-250 */
  2283     //   u2 offset_delta;
  2284     // }
  2285     else if (frame_type >= 248 && frame_type <= 250) {
  2286       stackmap_p += 2;
  2289     // same_frame_extended {
  2290     //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
  2291     //   u2 offset_delta;
  2292     // }
  2293     else if (frame_type == 251) {
  2294       stackmap_p += 2;
  2297     // append_frame {
  2298     //   u1 frame_type = APPEND; /* 252-254 */
  2299     //   u2 offset_delta;
  2300     //   verification_type_info locals[frame_type - 251];
  2301     // }
  2302     else if (frame_type >= 252 && frame_type <= 254) {
  2303       assert(stackmap_p + 2 <= stackmap_end,
  2304         "no room for offset_delta");
  2305       stackmap_p += 2;
  2306       u1 len = frame_type - 251;
  2307       for (u1 i = 0; i < len; i++) {
  2308         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
  2309           calc_number_of_entries, frame_type, THREAD);
  2313     // full_frame {
  2314     //   u1 frame_type = FULL_FRAME; /* 255 */
  2315     //   u2 offset_delta;
  2316     //   u2 number_of_locals;
  2317     //   verification_type_info locals[number_of_locals];
  2318     //   u2 number_of_stack_items;
  2319     //   verification_type_info stack[number_of_stack_items];
  2320     // }
  2321     else if (frame_type == 255) {
  2322       assert(stackmap_p + 2 + 2 <= stackmap_end,
  2323         "no room for smallest full_frame");
  2324       stackmap_p += 2;
  2326       u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
  2327       stackmap_p += 2;
  2329       for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
  2330         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
  2331           calc_number_of_entries, frame_type, THREAD);
  2334       // Use the largest size for the number_of_stack_items, but only get
  2335       // the right number of bytes.
  2336       u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
  2337       stackmap_p += 2;
  2339       for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
  2340         rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
  2341           calc_number_of_entries, frame_type, THREAD);
  2344   } // end while there is a stack_map_frame
  2345   assert(number_of_entries == calc_number_of_entries, "sanity check");
  2346 } // end rewrite_cp_refs_in_stack_map_table()
  2349 // Rewrite constant pool references in the verification type info
  2350 // portion of the method's stackmap table. These "structures" are
  2351 // adapted from the StackMapTable_attribute that is described in
  2352 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
  2353 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
  2354 //
  2355 // The verification_type_info structure is a u1 tag followed by 0 or
  2356 // more bytes of data:
  2357 //
  2358 // union verification_type_info {
  2359 //   Top_variable_info;
  2360 //   Integer_variable_info;
  2361 //   Float_variable_info;
  2362 //   Long_variable_info;
  2363 //   Double_variable_info;
  2364 //   Null_variable_info;
  2365 //   UninitializedThis_variable_info;
  2366 //   Object_variable_info;
  2367 //   Uninitialized_variable_info;
  2368 // }
  2369 //
  2370 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
  2371        address& stackmap_p_ref, address stackmap_end, u2 frame_i,
  2372        u1 frame_type, TRAPS) {
  2374   assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
  2375   u1 tag = *stackmap_p_ref;
  2376   stackmap_p_ref++;
  2378   switch (tag) {
  2379   // Top_variable_info {
  2380   //   u1 tag = ITEM_Top; /* 0 */
  2381   // }
  2382   // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
  2383   case 0:  // fall through
  2385   // Integer_variable_info {
  2386   //   u1 tag = ITEM_Integer; /* 1 */
  2387   // }
  2388   case ITEM_Integer:  // fall through
  2390   // Float_variable_info {
  2391   //   u1 tag = ITEM_Float; /* 2 */
  2392   // }
  2393   case ITEM_Float:  // fall through
  2395   // Double_variable_info {
  2396   //   u1 tag = ITEM_Double; /* 3 */
  2397   // }
  2398   case ITEM_Double:  // fall through
  2400   // Long_variable_info {
  2401   //   u1 tag = ITEM_Long; /* 4 */
  2402   // }
  2403   case ITEM_Long:  // fall through
  2405   // Null_variable_info {
  2406   //   u1 tag = ITEM_Null; /* 5 */
  2407   // }
  2408   case ITEM_Null:  // fall through
  2410   // UninitializedThis_variable_info {
  2411   //   u1 tag = ITEM_UninitializedThis; /* 6 */
  2412   // }
  2413   case ITEM_UninitializedThis:
  2414     // nothing more to do for the above tag types
  2415     break;
  2417   // Object_variable_info {
  2418   //   u1 tag = ITEM_Object; /* 7 */
  2419   //   u2 cpool_index;
  2420   // }
  2421   case ITEM_Object:
  2423     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
  2424     u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
  2425     u2 new_cp_index = find_new_index(cpool_index);
  2426     if (new_cp_index != 0) {
  2427       RC_TRACE_WITH_THREAD(0x04000000, THREAD,
  2428         ("mapped old cpool_index=%d", cpool_index));
  2429       Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
  2430       cpool_index = new_cp_index;
  2432     stackmap_p_ref += 2;
  2434     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
  2435       ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
  2436       frame_type, cpool_index));
  2437   } break;
  2439   // Uninitialized_variable_info {
  2440   //   u1 tag = ITEM_Uninitialized; /* 8 */
  2441   //   u2 offset;
  2442   // }
  2443   case ITEM_Uninitialized:
  2444     assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
  2445     stackmap_p_ref += 2;
  2446     break;
  2448   default:
  2449     RC_TRACE_WITH_THREAD(0x04000000, THREAD,
  2450       ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
  2451     ShouldNotReachHere();
  2452     break;
  2453   } // end switch (tag)
  2454 } // end rewrite_cp_refs_in_verification_type_info()
  2457 // Change the constant pool associated with klass scratch_class to
  2458 // scratch_cp. If shrink is true, then scratch_cp_length elements
  2459 // are copied from scratch_cp to a smaller constant pool and the
  2460 // smaller constant pool is associated with scratch_class.
  2461 void VM_RedefineClasses::set_new_constant_pool(
  2462        ClassLoaderData* loader_data,
  2463        instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
  2464        int scratch_cp_length, TRAPS) {
  2465   assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
  2467   // scratch_cp is a merged constant pool and has enough space for a
  2468   // worst case merge situation. We want to associate the minimum
  2469   // sized constant pool with the klass to save space.
  2470   constantPoolHandle smaller_cp(THREAD,
  2471           ConstantPool::allocate(loader_data, scratch_cp_length, THREAD));
  2473   // preserve version() value in the smaller copy
  2474   int version = scratch_cp->version();
  2475   assert(version != 0, "sanity check");
  2476   smaller_cp->set_version(version);
  2478   // attach klass to new constant pool
  2479   // reference to the cp holder is needed for copy_operands()
  2480   smaller_cp->set_pool_holder(scratch_class());
  2482   scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
  2483   scratch_cp = smaller_cp;
  2485   // attach new constant pool to klass
  2486   scratch_class->set_constants(scratch_cp());
  2488   int i;  // for portability
  2490   // update each field in klass to use new constant pool indices as needed
  2491   for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
  2492     jshort cur_index = fs.name_index();
  2493     jshort new_index = find_new_index(cur_index);
  2494     if (new_index != 0) {
  2495       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2496         ("field-name_index change: %d to %d", cur_index, new_index));
  2497       fs.set_name_index(new_index);
  2499     cur_index = fs.signature_index();
  2500     new_index = find_new_index(cur_index);
  2501     if (new_index != 0) {
  2502       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2503         ("field-signature_index change: %d to %d", cur_index, new_index));
  2504       fs.set_signature_index(new_index);
  2506     cur_index = fs.initval_index();
  2507     new_index = find_new_index(cur_index);
  2508     if (new_index != 0) {
  2509       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2510         ("field-initval_index change: %d to %d", cur_index, new_index));
  2511       fs.set_initval_index(new_index);
  2513     cur_index = fs.generic_signature_index();
  2514     new_index = find_new_index(cur_index);
  2515     if (new_index != 0) {
  2516       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2517         ("field-generic_signature change: %d to %d", cur_index, new_index));
  2518       fs.set_generic_signature_index(new_index);
  2520   } // end for each field
  2522   // Update constant pool indices in the inner classes info to use
  2523   // new constant indices as needed. The inner classes info is a
  2524   // quadruple:
  2525   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
  2526   InnerClassesIterator iter(scratch_class);
  2527   for (; !iter.done(); iter.next()) {
  2528     int cur_index = iter.inner_class_info_index();
  2529     if (cur_index == 0) {
  2530       continue;  // JVM spec. allows null inner class refs so skip it
  2532     int new_index = find_new_index(cur_index);
  2533     if (new_index != 0) {
  2534       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2535         ("inner_class_info change: %d to %d", cur_index, new_index));
  2536       iter.set_inner_class_info_index(new_index);
  2538     cur_index = iter.outer_class_info_index();
  2539     new_index = find_new_index(cur_index);
  2540     if (new_index != 0) {
  2541       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2542         ("outer_class_info change: %d to %d", cur_index, new_index));
  2543       iter.set_outer_class_info_index(new_index);
  2545     cur_index = iter.inner_name_index();
  2546     new_index = find_new_index(cur_index);
  2547     if (new_index != 0) {
  2548       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2549         ("inner_name change: %d to %d", cur_index, new_index));
  2550       iter.set_inner_name_index(new_index);
  2552   } // end for each inner class
  2554   // Attach each method in klass to the new constant pool and update
  2555   // to use new constant pool indices as needed:
  2556   Array<Method*>* methods = scratch_class->methods();
  2557   for (i = methods->length() - 1; i >= 0; i--) {
  2558     methodHandle method(THREAD, methods->at(i));
  2559     method->set_constants(scratch_cp());
  2561     int new_index = find_new_index(method->name_index());
  2562     if (new_index != 0) {
  2563       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2564         ("method-name_index change: %d to %d", method->name_index(),
  2565         new_index));
  2566       method->set_name_index(new_index);
  2568     new_index = find_new_index(method->signature_index());
  2569     if (new_index != 0) {
  2570       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2571         ("method-signature_index change: %d to %d",
  2572         method->signature_index(), new_index));
  2573       method->set_signature_index(new_index);
  2575     new_index = find_new_index(method->generic_signature_index());
  2576     if (new_index != 0) {
  2577       RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2578         ("method-generic_signature_index change: %d to %d",
  2579         method->generic_signature_index(), new_index));
  2580       method->set_generic_signature_index(new_index);
  2583     // Update constant pool indices in the method's checked exception
  2584     // table to use new constant indices as needed.
  2585     int cext_length = method->checked_exceptions_length();
  2586     if (cext_length > 0) {
  2587       CheckedExceptionElement * cext_table =
  2588         method->checked_exceptions_start();
  2589       for (int j = 0; j < cext_length; j++) {
  2590         int cur_index = cext_table[j].class_cp_index;
  2591         int new_index = find_new_index(cur_index);
  2592         if (new_index != 0) {
  2593           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2594             ("cext-class_cp_index change: %d to %d", cur_index, new_index));
  2595           cext_table[j].class_cp_index = (u2)new_index;
  2597       } // end for each checked exception table entry
  2598     } // end if there are checked exception table entries
  2600     // Update each catch type index in the method's exception table
  2601     // to use new constant pool indices as needed. The exception table
  2602     // holds quadruple entries of the form:
  2603     //   (beg_bci, end_bci, handler_bci, klass_index)
  2605     ExceptionTable ex_table(method());
  2606     int ext_length = ex_table.length();
  2608     for (int j = 0; j < ext_length; j ++) {
  2609       int cur_index = ex_table.catch_type_index(j);
  2610       int new_index = find_new_index(cur_index);
  2611       if (new_index != 0) {
  2612         RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2613           ("ext-klass_index change: %d to %d", cur_index, new_index));
  2614         ex_table.set_catch_type_index(j, new_index);
  2616     } // end for each exception table entry
  2618     // Update constant pool indices in the method's local variable
  2619     // table to use new constant indices as needed. The local variable
  2620     // table hold sextuple entries of the form:
  2621     // (start_pc, length, name_index, descriptor_index, signature_index, slot)
  2622     int lvt_length = method->localvariable_table_length();
  2623     if (lvt_length > 0) {
  2624       LocalVariableTableElement * lv_table =
  2625         method->localvariable_table_start();
  2626       for (int j = 0; j < lvt_length; j++) {
  2627         int cur_index = lv_table[j].name_cp_index;
  2628         int new_index = find_new_index(cur_index);
  2629         if (new_index != 0) {
  2630           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2631             ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
  2632           lv_table[j].name_cp_index = (u2)new_index;
  2634         cur_index = lv_table[j].descriptor_cp_index;
  2635         new_index = find_new_index(cur_index);
  2636         if (new_index != 0) {
  2637           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2638             ("lvt-descriptor_cp_index change: %d to %d", cur_index,
  2639             new_index));
  2640           lv_table[j].descriptor_cp_index = (u2)new_index;
  2642         cur_index = lv_table[j].signature_cp_index;
  2643         new_index = find_new_index(cur_index);
  2644         if (new_index != 0) {
  2645           RC_TRACE_WITH_THREAD(0x00080000, THREAD,
  2646             ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
  2647           lv_table[j].signature_cp_index = (u2)new_index;
  2649       } // end for each local variable table entry
  2650     } // end if there are local variable table entries
  2652     rewrite_cp_refs_in_stack_map_table(method, THREAD);
  2653   } // end for each method
  2654 } // end set_new_constant_pool()
  2657 // Unevolving classes may point to methods of the_class directly
  2658 // from their constant pool caches, itables, and/or vtables. We
  2659 // use the ClassLoaderDataGraph::classes_do() facility and this helper
  2660 // to fix up these pointers.
  2662 // Adjust cpools and vtables closure
  2663 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
  2665   // This is a very busy routine. We don't want too much tracing
  2666   // printed out.
  2667   bool trace_name_printed = false;
  2669   // Very noisy: only enable this call if you are trying to determine
  2670   // that a specific class gets found by this routine.
  2671   // RC_TRACE macro has an embedded ResourceMark
  2672   // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
  2673   //   ("adjust check: name=%s", k->external_name()));
  2674   // trace_name_printed = true;
  2676   // If the class being redefined is java.lang.Object, we need to fix all
  2677   // array class vtables also
  2678   if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
  2679     k->vtable()->adjust_method_entries(_matching_old_methods,
  2680                                        _matching_new_methods,
  2681                                        _matching_methods_length,
  2682                                        &trace_name_printed);
  2683   } else if (k->oop_is_instance()) {
  2684     HandleMark hm(_thread);
  2685     InstanceKlass *ik = InstanceKlass::cast(k);
  2687     // HotSpot specific optimization! HotSpot does not currently
  2688     // support delegation from the bootstrap class loader to a
  2689     // user-defined class loader. This means that if the bootstrap
  2690     // class loader is the initiating class loader, then it will also
  2691     // be the defining class loader. This also means that classes
  2692     // loaded by the bootstrap class loader cannot refer to classes
  2693     // loaded by a user-defined class loader. Note: a user-defined
  2694     // class loader can delegate to the bootstrap class loader.
  2695     //
  2696     // If the current class being redefined has a user-defined class
  2697     // loader as its defining class loader, then we can skip all
  2698     // classes loaded by the bootstrap class loader.
  2699     bool is_user_defined =
  2700            InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
  2701     if (is_user_defined && ik->class_loader() == NULL) {
  2702       return;
  2705     // Fix the vtable embedded in the_class and subclasses of the_class,
  2706     // if one exists. We discard scratch_class and we don't keep an
  2707     // InstanceKlass around to hold obsolete methods so we don't have
  2708     // any other InstanceKlass embedded vtables to update. The vtable
  2709     // holds the Method*s for virtual (but not final) methods.
  2710     if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
  2711       // ik->vtable() creates a wrapper object; rm cleans it up
  2712       ResourceMark rm(_thread);
  2713       ik->vtable()->adjust_method_entries(_matching_old_methods,
  2714                                           _matching_new_methods,
  2715                                           _matching_methods_length,
  2716                                           &trace_name_printed);
  2719     // If the current class has an itable and we are either redefining an
  2720     // interface or if the current class is a subclass of the_class, then
  2721     // we potentially have to fix the itable. If we are redefining an
  2722     // interface, then we have to call adjust_method_entries() for
  2723     // every InstanceKlass that has an itable since there isn't a
  2724     // subclass relationship between an interface and an InstanceKlass.
  2725     if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
  2726         || ik->is_subclass_of(_the_class_oop))) {
  2727       // ik->itable() creates a wrapper object; rm cleans it up
  2728       ResourceMark rm(_thread);
  2729       ik->itable()->adjust_method_entries(_matching_old_methods,
  2730                                           _matching_new_methods,
  2731                                           _matching_methods_length,
  2732                                           &trace_name_printed);
  2735     // The constant pools in other classes (other_cp) can refer to
  2736     // methods in the_class. We have to update method information in
  2737     // other_cp's cache. If other_cp has a previous version, then we
  2738     // have to repeat the process for each previous version. The
  2739     // constant pool cache holds the Method*s for non-virtual
  2740     // methods and for virtual, final methods.
  2741     //
  2742     // Special case: if the current class is the_class, then new_cp
  2743     // has already been attached to the_class and old_cp has already
  2744     // been added as a previous version. The new_cp doesn't have any
  2745     // cached references to old methods so it doesn't need to be
  2746     // updated. We can simply start with the previous version(s) in
  2747     // that case.
  2748     constantPoolHandle other_cp;
  2749     ConstantPoolCache* cp_cache;
  2751     if (ik != _the_class_oop) {
  2752       // this klass' constant pool cache may need adjustment
  2753       other_cp = constantPoolHandle(ik->constants());
  2754       cp_cache = other_cp->cache();
  2755       if (cp_cache != NULL) {
  2756         cp_cache->adjust_method_entries(_matching_old_methods,
  2757                                         _matching_new_methods,
  2758                                         _matching_methods_length,
  2759                                         &trace_name_printed);
  2763       ResourceMark rm(_thread);
  2764       // PreviousVersionInfo objects returned via PreviousVersionWalker
  2765       // contain a GrowableArray of handles. We have to clean up the
  2766       // GrowableArray _after_ the PreviousVersionWalker destructor
  2767       // has destroyed the handles.
  2769         // the previous versions' constant pool caches may need adjustment
  2770         PreviousVersionWalker pvw(ik);
  2771         for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
  2772              pv_info != NULL; pv_info = pvw.next_previous_version()) {
  2773           other_cp = pv_info->prev_constant_pool_handle();
  2774           cp_cache = other_cp->cache();
  2775           if (cp_cache != NULL) {
  2776             cp_cache->adjust_method_entries(_matching_old_methods,
  2777                                             _matching_new_methods,
  2778                                             _matching_methods_length,
  2779                                             &trace_name_printed);
  2782       } // pvw is cleaned up
  2783     } // rm is cleaned up
  2787 void VM_RedefineClasses::update_jmethod_ids() {
  2788   for (int j = 0; j < _matching_methods_length; ++j) {
  2789     Method* old_method = _matching_old_methods[j];
  2790     jmethodID jmid = old_method->find_jmethod_id_or_null();
  2791     if (jmid != NULL) {
  2792       // There is a jmethodID, change it to point to the new method
  2793       methodHandle new_method_h(_matching_new_methods[j]);
  2794       Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
  2795       assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
  2796              "should be replaced");
  2801 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
  2802        BitMap *emcp_methods, int * emcp_method_count_p) {
  2803   *emcp_method_count_p = 0;
  2804   int obsolete_count = 0;
  2805   int old_index = 0;
  2806   for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
  2807     Method* old_method = _matching_old_methods[j];
  2808     Method* new_method = _matching_new_methods[j];
  2809     Method* old_array_method;
  2811     // Maintain an old_index into the _old_methods array by skipping
  2812     // deleted methods
  2813     while ((old_array_method = _old_methods->at(old_index)) != old_method) {
  2814       ++old_index;
  2817     if (MethodComparator::methods_EMCP(old_method, new_method)) {
  2818       // The EMCP definition from JSR-163 requires the bytecodes to be
  2819       // the same with the exception of constant pool indices which may
  2820       // differ. However, the constants referred to by those indices
  2821       // must be the same.
  2822       //
  2823       // We use methods_EMCP() for comparison since constant pool
  2824       // merging can remove duplicate constant pool entries that were
  2825       // present in the old method and removed from the rewritten new
  2826       // method. A faster binary comparison function would consider the
  2827       // old and new methods to be different when they are actually
  2828       // EMCP.
  2829       //
  2830       // The old and new methods are EMCP and you would think that we
  2831       // could get rid of one of them here and now and save some space.
  2832       // However, the concept of EMCP only considers the bytecodes and
  2833       // the constant pool entries in the comparison. Other things,
  2834       // e.g., the line number table (LNT) or the local variable table
  2835       // (LVT) don't count in the comparison. So the new (and EMCP)
  2836       // method can have a new LNT that we need so we can't just
  2837       // overwrite the new method with the old method.
  2838       //
  2839       // When this routine is called, we have already attached the new
  2840       // methods to the_class so the old methods are effectively
  2841       // overwritten. However, if an old method is still executing,
  2842       // then the old method cannot be collected until sometime after
  2843       // the old method call has returned. So the overwriting of old
  2844       // methods by new methods will save us space except for those
  2845       // (hopefully few) old methods that are still executing.
  2846       //
  2847       // A method refers to a ConstMethod* and this presents another
  2848       // possible avenue to space savings. The ConstMethod* in the
  2849       // new method contains possibly new attributes (LNT, LVT, etc).
  2850       // At first glance, it seems possible to save space by replacing
  2851       // the ConstMethod* in the old method with the ConstMethod*
  2852       // from the new method. The old and new methods would share the
  2853       // same ConstMethod* and we would save the space occupied by
  2854       // the old ConstMethod*. However, the ConstMethod* contains
  2855       // a back reference to the containing method. Sharing the
  2856       // ConstMethod* between two methods could lead to confusion in
  2857       // the code that uses the back reference. This would lead to
  2858       // brittle code that could be broken in non-obvious ways now or
  2859       // in the future.
  2860       //
  2861       // Another possibility is to copy the ConstMethod* from the new
  2862       // method to the old method and then overwrite the new method with
  2863       // the old method. Since the ConstMethod* contains the bytecodes
  2864       // for the method embedded in the oop, this option would change
  2865       // the bytecodes out from under any threads executing the old
  2866       // method and make the thread's bcp invalid. Since EMCP requires
  2867       // that the bytecodes be the same modulo constant pool indices, it
  2868       // is straight forward to compute the correct new bcp in the new
  2869       // ConstMethod* from the old bcp in the old ConstMethod*. The
  2870       // time consuming part would be searching all the frames in all
  2871       // of the threads to find all of the calls to the old method.
  2872       //
  2873       // It looks like we will have to live with the limited savings
  2874       // that we get from effectively overwriting the old methods
  2875       // when the new methods are attached to the_class.
  2877       // track which methods are EMCP for add_previous_version() call
  2878       emcp_methods->set_bit(old_index);
  2879       (*emcp_method_count_p)++;
  2881       // An EMCP method is _not_ obsolete. An obsolete method has a
  2882       // different jmethodID than the current method. An EMCP method
  2883       // has the same jmethodID as the current method. Having the
  2884       // same jmethodID for all EMCP versions of a method allows for
  2885       // a consistent view of the EMCP methods regardless of which
  2886       // EMCP method you happen to have in hand. For example, a
  2887       // breakpoint set in one EMCP method will work for all EMCP
  2888       // versions of the method including the current one.
  2889     } else {
  2890       // mark obsolete methods as such
  2891       old_method->set_is_obsolete();
  2892       obsolete_count++;
  2894       // obsolete methods need a unique idnum
  2895       u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
  2896       if (num != ConstMethod::UNSET_IDNUM) {
  2897 //      u2 old_num = old_method->method_idnum();
  2898         old_method->set_method_idnum(num);
  2899 // TO DO: attach obsolete annotations to obsolete method's new idnum
  2901       // With tracing we try not to "yack" too much. The position of
  2902       // this trace assumes there are fewer obsolete methods than
  2903       // EMCP methods.
  2904       RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
  2905         old_method->name()->as_C_string(),
  2906         old_method->signature()->as_C_string()));
  2908     old_method->set_is_old();
  2910   for (int i = 0; i < _deleted_methods_length; ++i) {
  2911     Method* old_method = _deleted_methods[i];
  2913     assert(old_method->vtable_index() < 0,
  2914            "cannot delete methods with vtable entries");;
  2916     // Mark all deleted methods as old and obsolete
  2917     old_method->set_is_old();
  2918     old_method->set_is_obsolete();
  2919     ++obsolete_count;
  2920     // With tracing we try not to "yack" too much. The position of
  2921     // this trace assumes there are fewer obsolete methods than
  2922     // EMCP methods.
  2923     RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
  2924                           old_method->name()->as_C_string(),
  2925                           old_method->signature()->as_C_string()));
  2927   assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
  2928     "sanity check");
  2929   RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
  2930     obsolete_count));
  2933 // This internal class transfers the native function registration from old methods
  2934 // to new methods.  It is designed to handle both the simple case of unchanged
  2935 // native methods and the complex cases of native method prefixes being added and/or
  2936 // removed.
  2937 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
  2938 //
  2939 // This class is used after the new methods have been installed in "the_class".
  2940 //
  2941 // So, for example, the following must be handled.  Where 'm' is a method and
  2942 // a number followed by an underscore is a prefix.
  2943 //
  2944 //                                      Old Name    New Name
  2945 // Simple transfer to new method        m       ->  m
  2946 // Add prefix                           m       ->  1_m
  2947 // Remove prefix                        1_m     ->  m
  2948 // Simultaneous add of prefixes         m       ->  3_2_1_m
  2949 // Simultaneous removal of prefixes     3_2_1_m ->  m
  2950 // Simultaneous add and remove          1_m     ->  2_m
  2951 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
  2952 //
  2953 class TransferNativeFunctionRegistration {
  2954  private:
  2955   instanceKlassHandle the_class;
  2956   int prefix_count;
  2957   char** prefixes;
  2959   // Recursively search the binary tree of possibly prefixed method names.
  2960   // Iteration could be used if all agents were well behaved. Full tree walk is
  2961   // more resilent to agents not cleaning up intermediate methods.
  2962   // Branch at each depth in the binary tree is:
  2963   //    (1) without the prefix.
  2964   //    (2) with the prefix.
  2965   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
  2966   Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
  2967                                      Symbol* signature) {
  2968     TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
  2969     if (name_symbol != NULL) {
  2970       Method* method = the_class()->lookup_method(name_symbol, signature);
  2971       if (method != NULL) {
  2972         // Even if prefixed, intermediate methods must exist.
  2973         if (method->is_native()) {
  2974           // Wahoo, we found a (possibly prefixed) version of the method, return it.
  2975           return method;
  2977         if (depth < prefix_count) {
  2978           // Try applying further prefixes (other than this one).
  2979           method = search_prefix_name_space(depth+1, name_str, name_len, signature);
  2980           if (method != NULL) {
  2981             return method; // found
  2984           // Try adding this prefix to the method name and see if it matches
  2985           // another method name.
  2986           char* prefix = prefixes[depth];
  2987           size_t prefix_len = strlen(prefix);
  2988           size_t trial_len = name_len + prefix_len;
  2989           char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
  2990           strcpy(trial_name_str, prefix);
  2991           strcat(trial_name_str, name_str);
  2992           method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
  2993                                             signature);
  2994           if (method != NULL) {
  2995             // If found along this branch, it was prefixed, mark as such
  2996             method->set_is_prefixed_native();
  2997             return method; // found
  3002     return NULL;  // This whole branch bore nothing
  3005   // Return the method name with old prefixes stripped away.
  3006   char* method_name_without_prefixes(Method* method) {
  3007     Symbol* name = method->name();
  3008     char* name_str = name->as_utf8();
  3010     // Old prefixing may be defunct, strip prefixes, if any.
  3011     for (int i = prefix_count-1; i >= 0; i--) {
  3012       char* prefix = prefixes[i];
  3013       size_t prefix_len = strlen(prefix);
  3014       if (strncmp(prefix, name_str, prefix_len) == 0) {
  3015         name_str += prefix_len;
  3018     return name_str;
  3021   // Strip any prefixes off the old native method, then try to find a
  3022   // (possibly prefixed) new native that matches it.
  3023   Method* strip_and_search_for_new_native(Method* method) {
  3024     ResourceMark rm;
  3025     char* name_str = method_name_without_prefixes(method);
  3026     return search_prefix_name_space(0, name_str, strlen(name_str),
  3027                                     method->signature());
  3030  public:
  3032   // Construct a native method transfer processor for this class.
  3033   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
  3034     assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
  3036     the_class = _the_class;
  3037     prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
  3040   // Attempt to transfer any of the old or deleted methods that are native
  3041   void transfer_registrations(Method** old_methods, int methods_length) {
  3042     for (int j = 0; j < methods_length; j++) {
  3043       Method* old_method = old_methods[j];
  3045       if (old_method->is_native() && old_method->has_native_function()) {
  3046         Method* new_method = strip_and_search_for_new_native(old_method);
  3047         if (new_method != NULL) {
  3048           // Actually set the native function in the new method.
  3049           // Redefine does not send events (except CFLH), certainly not this
  3050           // behind the scenes re-registration.
  3051           new_method->set_native_function(old_method->native_function(),
  3052                               !Method::native_bind_event_is_interesting);
  3057 };
  3059 // Don't lose the association between a native method and its JNI function.
  3060 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
  3061   TransferNativeFunctionRegistration transfer(the_class);
  3062   transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
  3063   transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
  3066 // Deoptimize all compiled code that depends on this class.
  3067 //
  3068 // If the can_redefine_classes capability is obtained in the onload
  3069 // phase then the compiler has recorded all dependencies from startup.
  3070 // In that case we need only deoptimize and throw away all compiled code
  3071 // that depends on the class.
  3072 //
  3073 // If can_redefine_classes is obtained sometime after the onload
  3074 // phase then the dependency information may be incomplete. In that case
  3075 // the first call to RedefineClasses causes all compiled code to be
  3076 // thrown away. As can_redefine_classes has been obtained then
  3077 // all future compilations will record dependencies so second and
  3078 // subsequent calls to RedefineClasses need only throw away code
  3079 // that depends on the class.
  3080 //
  3081 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
  3082   assert_locked_or_safepoint(Compile_lock);
  3084   // All dependencies have been recorded from startup or this is a second or
  3085   // subsequent use of RedefineClasses
  3086   if (JvmtiExport::all_dependencies_are_recorded()) {
  3087     Universe::flush_evol_dependents_on(k_h);
  3088   } else {
  3089     CodeCache::mark_all_nmethods_for_deoptimization();
  3091     ResourceMark rm(THREAD);
  3092     DeoptimizationMarker dm;
  3094     // Deoptimize all activations depending on marked nmethods
  3095     Deoptimization::deoptimize_dependents();
  3097     // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
  3098     CodeCache::make_marked_nmethods_not_entrant();
  3100     // From now on we know that the dependency information is complete
  3101     JvmtiExport::set_all_dependencies_are_recorded(true);
  3105 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
  3106   Method* old_method;
  3107   Method* new_method;
  3109   _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
  3110   _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
  3111   _added_methods        = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
  3112   _deleted_methods      = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
  3114   _matching_methods_length = 0;
  3115   _deleted_methods_length  = 0;
  3116   _added_methods_length    = 0;
  3118   int nj = 0;
  3119   int oj = 0;
  3120   while (true) {
  3121     if (oj >= _old_methods->length()) {
  3122       if (nj >= _new_methods->length()) {
  3123         break; // we've looked at everything, done
  3125       // New method at the end
  3126       new_method = _new_methods->at(nj);
  3127       _added_methods[_added_methods_length++] = new_method;
  3128       ++nj;
  3129     } else if (nj >= _new_methods->length()) {
  3130       // Old method, at the end, is deleted
  3131       old_method = _old_methods->at(oj);
  3132       _deleted_methods[_deleted_methods_length++] = old_method;
  3133       ++oj;
  3134     } else {
  3135       old_method = _old_methods->at(oj);
  3136       new_method = _new_methods->at(nj);
  3137       if (old_method->name() == new_method->name()) {
  3138         if (old_method->signature() == new_method->signature()) {
  3139           _matching_old_methods[_matching_methods_length  ] = old_method;
  3140           _matching_new_methods[_matching_methods_length++] = new_method;
  3141           ++nj;
  3142           ++oj;
  3143         } else {
  3144           // added overloaded have already been moved to the end,
  3145           // so this is a deleted overloaded method
  3146           _deleted_methods[_deleted_methods_length++] = old_method;
  3147           ++oj;
  3149       } else { // names don't match
  3150         if (old_method->name()->fast_compare(new_method->name()) > 0) {
  3151           // new method
  3152           _added_methods[_added_methods_length++] = new_method;
  3153           ++nj;
  3154         } else {
  3155           // deleted method
  3156           _deleted_methods[_deleted_methods_length++] = old_method;
  3157           ++oj;
  3162   assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
  3163   assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
  3167 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
  3168                                           instanceKlassHandle scratch_class) {
  3169   // Since there is currently no rewriting of type annotations indexes
  3170   // into the CP, we null out type annotations on scratch_class before
  3171   // we swap annotations with the_class rather than facing the
  3172   // possibility of shipping annotations with broken indexes to
  3173   // Java-land.
  3174   ClassLoaderData* loader_data = scratch_class->class_loader_data();
  3175   AnnotationArray* new_class_type_annotations = scratch_class->class_type_annotations();
  3176   if (new_class_type_annotations != NULL) {
  3177     MetadataFactory::free_array<u1>(loader_data, new_class_type_annotations);
  3178     scratch_class->annotations()->set_class_type_annotations(NULL);
  3180   Array<AnnotationArray*>* new_field_type_annotations = scratch_class->fields_type_annotations();
  3181   if (new_field_type_annotations != NULL) {
  3182     Annotations::free_contents(loader_data, new_field_type_annotations);
  3183     scratch_class->annotations()->set_fields_type_annotations(NULL);
  3186   // Swap annotation fields values
  3187   Annotations* old_annotations = the_class->annotations();
  3188   the_class->set_annotations(scratch_class->annotations());
  3189   scratch_class->set_annotations(old_annotations);
  3193 // Install the redefinition of a class:
  3194 //    - house keeping (flushing breakpoints and caches, deoptimizing
  3195 //      dependent compiled code)
  3196 //    - replacing parts in the_class with parts from scratch_class
  3197 //    - adding a weak reference to track the obsolete but interesting
  3198 //      parts of the_class
  3199 //    - adjusting constant pool caches and vtables in other classes
  3200 //      that refer to methods in the_class. These adjustments use the
  3201 //      ClassLoaderDataGraph::classes_do() facility which only allows
  3202 //      a helper method to be specified. The interesting parameters
  3203 //      that we would like to pass to the helper method are saved in
  3204 //      static global fields in the VM operation.
  3205 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
  3206        Klass* scratch_class_oop, TRAPS) {
  3208   HandleMark hm(THREAD);   // make sure handles from this call are freed
  3209   RC_TIMER_START(_timer_rsc_phase1);
  3211   instanceKlassHandle scratch_class(scratch_class_oop);
  3213   oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
  3214   Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
  3215   instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
  3217   // Remove all breakpoints in methods of this class
  3218   JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
  3219   jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
  3221   if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
  3222     // We are redefining java.lang.reflect.Method. Method.invoke() is
  3223     // cached and users of the cache care about each active version of
  3224     // the method so we have to track this previous version.
  3225     // Do this before methods get switched
  3226     Universe::reflect_invoke_cache()->add_previous_version(
  3227       the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
  3230   // Deoptimize all compiled code that depends on this class
  3231   flush_dependent_code(the_class, THREAD);
  3233   _old_methods = the_class->methods();
  3234   _new_methods = scratch_class->methods();
  3235   _the_class_oop = the_class_oop;
  3236   compute_added_deleted_matching_methods();
  3237   update_jmethod_ids();
  3239   // Attach new constant pool to the original klass. The original
  3240   // klass still refers to the old constant pool (for now).
  3241   scratch_class->constants()->set_pool_holder(the_class());
  3243 #if 0
  3244   // In theory, with constant pool merging in place we should be able
  3245   // to save space by using the new, merged constant pool in place of
  3246   // the old constant pool(s). By "pool(s)" I mean the constant pool in
  3247   // the klass version we are replacing now and any constant pool(s) in
  3248   // previous versions of klass. Nice theory, doesn't work in practice.
  3249   // When this code is enabled, even simple programs throw NullPointer
  3250   // exceptions. I'm guessing that this is caused by some constant pool
  3251   // cache difference between the new, merged constant pool and the
  3252   // constant pool that was just being used by the klass. I'm keeping
  3253   // this code around to archive the idea, but the code has to remain
  3254   // disabled for now.
  3256   // Attach each old method to the new constant pool. This can be
  3257   // done here since we are past the bytecode verification and
  3258   // constant pool optimization phases.
  3259   for (int i = _old_methods->length() - 1; i >= 0; i--) {
  3260     Method* method = _old_methods->at(i);
  3261     method->set_constants(scratch_class->constants());
  3265     // walk all previous versions of the klass
  3266     InstanceKlass *ik = (InstanceKlass *)the_class();
  3267     PreviousVersionWalker pvw(ik);
  3268     instanceKlassHandle ikh;
  3269     do {
  3270       ikh = pvw.next_previous_version();
  3271       if (!ikh.is_null()) {
  3272         ik = ikh();
  3274         // attach previous version of klass to the new constant pool
  3275         ik->set_constants(scratch_class->constants());
  3277         // Attach each method in the previous version of klass to the
  3278         // new constant pool
  3279         Array<Method*>* prev_methods = ik->methods();
  3280         for (int i = prev_methods->length() - 1; i >= 0; i--) {
  3281           Method* method = prev_methods->at(i);
  3282           method->set_constants(scratch_class->constants());
  3285     } while (!ikh.is_null());
  3287 #endif
  3289   // Replace methods and constantpool
  3290   the_class->set_methods(_new_methods);
  3291   scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
  3292                                           // and to be able to undo operation easily.
  3294   ConstantPool* old_constants = the_class->constants();
  3295   the_class->set_constants(scratch_class->constants());
  3296   scratch_class->set_constants(old_constants);  // See the previous comment.
  3297 #if 0
  3298   // We are swapping the guts of "the new class" with the guts of "the
  3299   // class". Since the old constant pool has just been attached to "the
  3300   // new class", it seems logical to set the pool holder in the old
  3301   // constant pool also. However, doing this will change the observable
  3302   // class hierarchy for any old methods that are still executing. A
  3303   // method can query the identity of its "holder" and this query uses
  3304   // the method's constant pool link to find the holder. The change in
  3305   // holding class from "the class" to "the new class" can confuse
  3306   // things.
  3307   //
  3308   // Setting the old constant pool's holder will also cause
  3309   // verification done during vtable initialization below to fail.
  3310   // During vtable initialization, the vtable's class is verified to be
  3311   // a subtype of the method's holder. The vtable's class is "the
  3312   // class" and the method's holder is gotten from the constant pool
  3313   // link in the method itself. For "the class"'s directly implemented
  3314   // methods, the method holder is "the class" itself (as gotten from
  3315   // the new constant pool). The check works fine in this case. The
  3316   // check also works fine for methods inherited from super classes.
  3317   //
  3318   // Miranda methods are a little more complicated. A miranda method is
  3319   // provided by an interface when the class implementing the interface
  3320   // does not provide its own method.  These interfaces are implemented
  3321   // internally as an InstanceKlass. These special instanceKlasses
  3322   // share the constant pool of the class that "implements" the
  3323   // interface. By sharing the constant pool, the method holder of a
  3324   // miranda method is the class that "implements" the interface. In a
  3325   // non-redefine situation, the subtype check works fine. However, if
  3326   // the old constant pool's pool holder is modified, then the check
  3327   // fails because there is no class hierarchy relationship between the
  3328   // vtable's class and "the new class".
  3330   old_constants->set_pool_holder(scratch_class());
  3331 #endif
  3333   // track which methods are EMCP for add_previous_version() call below
  3334   BitMap emcp_methods(_old_methods->length());
  3335   int emcp_method_count = 0;
  3336   emcp_methods.clear();  // clears 0..(length() - 1)
  3337   check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
  3338   transfer_old_native_function_registrations(the_class);
  3340   // The class file bytes from before any retransformable agents mucked
  3341   // with them was cached on the scratch class, move to the_class.
  3342   // Note: we still want to do this if nothing needed caching since it
  3343   // should get cleared in the_class too.
  3344   if (the_class->get_cached_class_file_bytes() == 0) {
  3345     // the_class doesn't have a cache yet so copy it
  3346     the_class->set_cached_class_file(
  3347       scratch_class->get_cached_class_file_bytes(),
  3348       scratch_class->get_cached_class_file_len());
  3350 #ifndef PRODUCT
  3351   else {
  3352     assert(the_class->get_cached_class_file_bytes() ==
  3353       scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
  3354     assert(the_class->get_cached_class_file_len() ==
  3355       scratch_class->get_cached_class_file_len(), "cache lens must match");
  3357 #endif
  3359   // NULL out in scratch class to not delete twice.  The class to be redefined
  3360   // always owns these bytes.
  3361   scratch_class->set_cached_class_file(NULL, 0);
  3363   // Replace inner_classes
  3364   Array<u2>* old_inner_classes = the_class->inner_classes();
  3365   the_class->set_inner_classes(scratch_class->inner_classes());
  3366   scratch_class->set_inner_classes(old_inner_classes);
  3368   // Initialize the vtable and interface table after
  3369   // methods have been rewritten
  3371     ResourceMark rm(THREAD);
  3372     // no exception should happen here since we explicitly
  3373     // do not check loader constraints.
  3374     // compare_and_normalize_class_versions has already checked:
  3375     //  - classloaders unchanged, signatures unchanged
  3376     //  - all instanceKlasses for redefined classes reused & contents updated
  3377     the_class->vtable()->initialize_vtable(false, THREAD);
  3378     the_class->itable()->initialize_itable(false, THREAD);
  3379     assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
  3382   // Leave arrays of jmethodIDs and itable index cache unchanged
  3384   // Copy the "source file name" attribute from new class version
  3385   the_class->set_source_file_name(scratch_class->source_file_name());
  3387   // Copy the "source debug extension" attribute from new class version
  3388   the_class->set_source_debug_extension(
  3389     scratch_class->source_debug_extension(),
  3390     scratch_class->source_debug_extension() == NULL ? 0 :
  3391     (int)strlen(scratch_class->source_debug_extension()));
  3393   // Use of javac -g could be different in the old and the new
  3394   if (scratch_class->access_flags().has_localvariable_table() !=
  3395       the_class->access_flags().has_localvariable_table()) {
  3397     AccessFlags flags = the_class->access_flags();
  3398     if (scratch_class->access_flags().has_localvariable_table()) {
  3399       flags.set_has_localvariable_table();
  3400     } else {
  3401       flags.clear_has_localvariable_table();
  3403     the_class->set_access_flags(flags);
  3406   swap_annotations(the_class, scratch_class);
  3408   // Replace minor version number of class file
  3409   u2 old_minor_version = the_class->minor_version();
  3410   the_class->set_minor_version(scratch_class->minor_version());
  3411   scratch_class->set_minor_version(old_minor_version);
  3413   // Replace major version number of class file
  3414   u2 old_major_version = the_class->major_version();
  3415   the_class->set_major_version(scratch_class->major_version());
  3416   scratch_class->set_major_version(old_major_version);
  3418   // Replace CP indexes for class and name+type of enclosing method
  3419   u2 old_class_idx  = the_class->enclosing_method_class_index();
  3420   u2 old_method_idx = the_class->enclosing_method_method_index();
  3421   the_class->set_enclosing_method_indices(
  3422     scratch_class->enclosing_method_class_index(),
  3423     scratch_class->enclosing_method_method_index());
  3424   scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
  3426   // keep track of previous versions of this class
  3427   the_class->add_previous_version(scratch_class, &emcp_methods,
  3428     emcp_method_count);
  3430   RC_TIMER_STOP(_timer_rsc_phase1);
  3431   RC_TIMER_START(_timer_rsc_phase2);
  3433   // Adjust constantpool caches and vtables for all classes
  3434   // that reference methods of the evolved class.
  3435   AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
  3436   ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
  3438   // JSR-292 support
  3439   MemberNameTable* mnt = the_class->member_names();
  3440   if (mnt != NULL) {
  3441     bool trace_name_printed = false;
  3442     mnt->adjust_method_entries(_matching_old_methods,
  3443                                _matching_new_methods,
  3444                                _matching_methods_length,
  3445                                &trace_name_printed);
  3448   // Fix Resolution Error table also to remove old constant pools
  3449   SystemDictionary::delete_resolution_error(old_constants);
  3451   if (the_class->oop_map_cache() != NULL) {
  3452     // Flush references to any obsolete methods from the oop map cache
  3453     // so that obsolete methods are not pinned.
  3454     the_class->oop_map_cache()->flush_obsolete_entries();
  3457   // increment the classRedefinedCount field in the_class and in any
  3458   // direct and indirect subclasses of the_class
  3459   increment_class_counter((InstanceKlass *)the_class(), THREAD);
  3461   // RC_TRACE macro has an embedded ResourceMark
  3462   RC_TRACE_WITH_THREAD(0x00000001, THREAD,
  3463     ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
  3464     the_class->external_name(),
  3465     java_lang_Class::classRedefinedCount(the_class_mirror),
  3466     os::available_memory() >> 10));
  3468   RC_TIMER_STOP(_timer_rsc_phase2);
  3469 } // end redefine_single_class()
  3472 // Increment the classRedefinedCount field in the specific InstanceKlass
  3473 // and in all direct and indirect subclasses.
  3474 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
  3475   oop class_mirror = ik->java_mirror();
  3476   Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
  3477   int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
  3478   java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
  3480   if (class_oop != _the_class_oop) {
  3481     // _the_class_oop count is printed at end of redefine_single_class()
  3482     RC_TRACE_WITH_THREAD(0x00000008, THREAD,
  3483       ("updated count in subclass=%s to %d", ik->external_name(), new_count));
  3486   for (Klass *subk = ik->subklass(); subk != NULL;
  3487        subk = subk->next_sibling()) {
  3488     if (subk->oop_is_instance()) {
  3489       // Only update instanceKlasses
  3490       InstanceKlass *subik = (InstanceKlass*)subk;
  3491       // recursively do subclasses of the current subclass
  3492       increment_class_counter(subik, THREAD);
  3497 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
  3498   bool no_old_methods = true;  // be optimistic
  3500   // Both array and instance classes have vtables.
  3501   // a vtable should never contain old or obsolete methods
  3502   ResourceMark rm(_thread);
  3503   if (k->vtable_length() > 0 &&
  3504       !k->vtable()->check_no_old_or_obsolete_entries()) {
  3505     if (RC_TRACE_ENABLED(0x00004000)) {
  3506       RC_TRACE_WITH_THREAD(0x00004000, _thread,
  3507         ("klassVtable::check_no_old_or_obsolete_entries failure"
  3508          " -- OLD or OBSOLETE method found -- class: %s",
  3509          k->signature_name()));
  3510       k->vtable()->dump_vtable();
  3512     no_old_methods = false;
  3515   if (k->oop_is_instance()) {
  3516     HandleMark hm(_thread);
  3517     InstanceKlass *ik = InstanceKlass::cast(k);
  3519     // an itable should never contain old or obsolete methods
  3520     if (ik->itable_length() > 0 &&
  3521         !ik->itable()->check_no_old_or_obsolete_entries()) {
  3522       if (RC_TRACE_ENABLED(0x00004000)) {
  3523         RC_TRACE_WITH_THREAD(0x00004000, _thread,
  3524           ("klassItable::check_no_old_or_obsolete_entries failure"
  3525            " -- OLD or OBSOLETE method found -- class: %s",
  3526            ik->signature_name()));
  3527         ik->itable()->dump_itable();
  3529       no_old_methods = false;
  3532     // the constant pool cache should never contain old or obsolete methods
  3533     if (ik->constants() != NULL &&
  3534         ik->constants()->cache() != NULL &&
  3535         !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
  3536       if (RC_TRACE_ENABLED(0x00004000)) {
  3537         RC_TRACE_WITH_THREAD(0x00004000, _thread,
  3538           ("cp-cache::check_no_old_or_obsolete_entries failure"
  3539            " -- OLD or OBSOLETE method found -- class: %s",
  3540            ik->signature_name()));
  3541         ik->constants()->cache()->dump_cache();
  3543       no_old_methods = false;
  3547   // print and fail guarantee if old methods are found.
  3548   if (!no_old_methods) {
  3549     if (RC_TRACE_ENABLED(0x00004000)) {
  3550       dump_methods();
  3551     } else {
  3552       tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
  3553         "to see more info about the following guarantee() failure.");
  3555     guarantee(false, "OLD and/or OBSOLETE method(s) found");
  3560 void VM_RedefineClasses::dump_methods() {
  3561   int j;
  3562   RC_TRACE(0x00004000, ("_old_methods --"));
  3563   for (j = 0; j < _old_methods->length(); ++j) {
  3564     Method* m = _old_methods->at(j);
  3565     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
  3566     m->access_flags().print_on(tty);
  3567     tty->print(" --  ");
  3568     m->print_name(tty);
  3569     tty->cr();
  3571   RC_TRACE(0x00004000, ("_new_methods --"));
  3572   for (j = 0; j < _new_methods->length(); ++j) {
  3573     Method* m = _new_methods->at(j);
  3574     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
  3575     m->access_flags().print_on(tty);
  3576     tty->print(" --  ");
  3577     m->print_name(tty);
  3578     tty->cr();
  3580   RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
  3581   for (j = 0; j < _matching_methods_length; ++j) {
  3582     Method* m = _matching_old_methods[j];
  3583     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
  3584     m->access_flags().print_on(tty);
  3585     tty->print(" --  ");
  3586     m->print_name(tty);
  3587     tty->cr();
  3588     m = _matching_new_methods[j];
  3589     RC_TRACE_NO_CR(0x00004000, ("      (%5d)  ", m->vtable_index()));
  3590     m->access_flags().print_on(tty);
  3591     tty->cr();
  3593   RC_TRACE(0x00004000, ("_deleted_methods --"));
  3594   for (j = 0; j < _deleted_methods_length; ++j) {
  3595     Method* m = _deleted_methods[j];
  3596     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
  3597     m->access_flags().print_on(tty);
  3598     tty->print(" --  ");
  3599     m->print_name(tty);
  3600     tty->cr();
  3602   RC_TRACE(0x00004000, ("_added_methods --"));
  3603   for (j = 0; j < _added_methods_length; ++j) {
  3604     Method* m = _added_methods[j];
  3605     RC_TRACE_NO_CR(0x00004000, ("%4d  (%5d)  ", j, m->vtable_index()));
  3606     m->access_flags().print_on(tty);
  3607     tty->print(" --  ");
  3608     m->print_name(tty);
  3609     tty->cr();

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