Java example source code file (jvmtiRedefineClasses.cpp)
The jvmtiRedefineClasses.cpp Java example source code/*
* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* questions.
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*/
#include "precompiled.hpp"
#include "classfile/metadataOnStackMark.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/verifier.hpp"
#include "code/codeCache.hpp"
#include "compiler/compileBroker.hpp"
#include "interpreter/oopMapCache.hpp"
#include "interpreter/rewriter.hpp"
#include "memory/gcLocker.hpp"
#include "memory/metadataFactory.hpp"
#include "memory/metaspaceShared.hpp"
#include "memory/universe.inline.hpp"
#include "oops/fieldStreams.hpp"
#include "oops/klassVtable.hpp"
#include "prims/jvmtiImpl.hpp"
#include "prims/jvmtiRedefineClasses.hpp"
#include "prims/methodComparator.hpp"
#include "runtime/deoptimization.hpp"
#include "runtime/relocator.hpp"
#include "utilities/bitMap.inline.hpp"
Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
Method** VM_RedefineClasses::_matching_old_methods = NULL;
Method** VM_RedefineClasses::_matching_new_methods = NULL;
Method** VM_RedefineClasses::_deleted_methods = NULL;
Method** VM_RedefineClasses::_added_methods = NULL;
int VM_RedefineClasses::_matching_methods_length = 0;
int VM_RedefineClasses::_deleted_methods_length = 0;
int VM_RedefineClasses::_added_methods_length = 0;
Klass* VM_RedefineClasses::_the_class_oop = NULL;
VM_RedefineClasses::VM_RedefineClasses(jint class_count,
const jvmtiClassDefinition *class_defs,
JvmtiClassLoadKind class_load_kind) {
_class_count = class_count;
_class_defs = class_defs;
_class_load_kind = class_load_kind;
_res = JVMTI_ERROR_NONE;
}
bool VM_RedefineClasses::doit_prologue() {
if (_class_count == 0) {
_res = JVMTI_ERROR_NONE;
return false;
}
if (_class_defs == NULL) {
_res = JVMTI_ERROR_NULL_POINTER;
return false;
}
for (int i = 0; i < _class_count; i++) {
if (_class_defs[i].klass == NULL) {
_res = JVMTI_ERROR_INVALID_CLASS;
return false;
}
if (_class_defs[i].class_byte_count == 0) {
_res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
return false;
}
if (_class_defs[i].class_bytes == NULL) {
_res = JVMTI_ERROR_NULL_POINTER;
return false;
}
}
// Start timer after all the sanity checks; not quite accurate, but
// better than adding a bunch of stop() calls.
RC_TIMER_START(_timer_vm_op_prologue);
// We first load new class versions in the prologue, because somewhere down the
// call chain it is required that the current thread is a Java thread.
_res = load_new_class_versions(Thread::current());
if (_res != JVMTI_ERROR_NONE) {
// free any successfully created classes, since none are redefined
for (int i = 0; i < _class_count; i++) {
if (_scratch_classes[i] != NULL) {
ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
// Free the memory for this class at class unloading time. Not before
// because CMS might think this is still live.
cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
}
}
// Free os::malloc allocated memory in load_new_class_version.
os::free(_scratch_classes);
RC_TIMER_STOP(_timer_vm_op_prologue);
return false;
}
RC_TIMER_STOP(_timer_vm_op_prologue);
return true;
}
void VM_RedefineClasses::doit() {
Thread *thread = Thread::current();
if (UseSharedSpaces) {
// Sharing is enabled so we remap the shared readonly space to
// shared readwrite, private just in case we need to redefine
// a shared class. We do the remap during the doit() phase of
// the safepoint to be safer.
if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
RC_TRACE_WITH_THREAD(0x00000001, thread,
("failed to remap shared readonly space to readwrite, private"));
_res = JVMTI_ERROR_INTERNAL;
return;
}
}
// Mark methods seen on stack and everywhere else so old methods are not
// cleaned up if they're on the stack.
MetadataOnStackMark md_on_stack;
HandleMark hm(thread); // make sure any handles created are deleted
// before the stack walk again.
for (int i = 0; i < _class_count; i++) {
redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
// Free the memory for this class at class unloading time. Not before
// because CMS might think this is still live.
cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
_scratch_classes[i] = NULL;
}
// Set flag indicating that some invariants are no longer true.
// See jvmtiExport.hpp for detailed explanation.
JvmtiExport::set_has_redefined_a_class();
// check_class() is optionally called for product bits, but is
// always called for non-product bits.
#ifdef PRODUCT
if (RC_TRACE_ENABLED(0x00004000)) {
#endif
RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
CheckClass check_class(thread);
ClassLoaderDataGraph::classes_do(&check_class);
#ifdef PRODUCT
}
#endif
}
void VM_RedefineClasses::doit_epilogue() {
// Free os::malloc allocated memory.
os::free(_scratch_classes);
if (RC_TRACE_ENABLED(0x00000004)) {
// Used to have separate timers for "doit" and "all", but the timer
// overhead skewed the measurements.
jlong doit_time = _timer_rsc_phase1.milliseconds() +
_timer_rsc_phase2.milliseconds();
jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
" prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time,
_timer_vm_op_prologue.milliseconds(), doit_time));
RC_TRACE(0x00000004,
("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT,
_timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
}
}
bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
// classes for primitives cannot be redefined
if (java_lang_Class::is_primitive(klass_mirror)) {
return false;
}
Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
// classes for arrays cannot be redefined
if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
return false;
}
return true;
}
// Append the current entry at scratch_i in scratch_cp to *merge_cp_p
// where the end of *merge_cp_p is specified by *merge_cp_length_p. For
// direct CP entries, there is just the current entry to append. For
// indirect and double-indirect CP entries, there are zero or more
// referenced CP entries along with the current entry to append.
// Indirect and double-indirect CP entries are handled by recursive
// calls to append_entry() as needed. The referenced CP entries are
// always appended to *merge_cp_p before the referee CP entry. These
// referenced CP entries may already exist in *merge_cp_p in which case
// there is nothing extra to append and only the current entry is
// appended.
void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
TRAPS) {
// append is different depending on entry tag type
switch (scratch_cp->tag_at(scratch_i).value()) {
// The old verifier is implemented outside the VM. It loads classes,
// but does not resolve constant pool entries directly so we never
// see Class entries here with the old verifier. Similarly the old
// verifier does not like Class entries in the input constant pool.
// The split-verifier is implemented in the VM so it can optionally
// and directly resolve constant pool entries to load classes. The
// split-verifier can accept either Class entries or UnresolvedClass
// entries in the input constant pool. We revert the appended copy
// back to UnresolvedClass so that either verifier will be happy
// with the constant pool entry.
case JVM_CONSTANT_Class:
{
// revert the copy to JVM_CONSTANT_UnresolvedClass
(*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
scratch_cp->klass_name_at(scratch_i));
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// these are direct CP entries so they can be directly appended,
// but double and long take two constant pool entries
case JVM_CONSTANT_Double: // fall through
case JVM_CONSTANT_Long:
{
ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
THREAD);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p) += 2;
} break;
// these are direct CP entries so they can be directly appended
case JVM_CONSTANT_Float: // fall through
case JVM_CONSTANT_Integer: // fall through
case JVM_CONSTANT_Utf8: // fall through
// This was an indirect CP entry, but it has been changed into
// Symbol*s so this entry can be directly appended.
case JVM_CONSTANT_String: // fall through
// These were indirect CP entries, but they have been changed into
// Symbol*s so these entries can be directly appended.
case JVM_CONSTANT_UnresolvedClass: // fall through
{
ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
THREAD);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// this is an indirect CP entry so it needs special handling
case JVM_CONSTANT_NameAndType:
{
int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
merge_cp_p, merge_cp_length_p,
THREAD);
// If the referenced entries already exist in *merge_cp_p, then
// both new_name_ref_i and new_signature_ref_i will both be 0.
// In that case, all we are appending is the current entry.
if (new_name_ref_i != name_ref_i) {
RC_TRACE(0x00080000,
("NameAndType entry@%d name_ref_index change: %d to %d",
*merge_cp_length_p, name_ref_i, new_name_ref_i));
}
if (new_signature_ref_i != signature_ref_i) {
RC_TRACE(0x00080000,
("NameAndType entry@%d signature_ref_index change: %d to %d",
*merge_cp_length_p, signature_ref_i, new_signature_ref_i));
}
(*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
new_name_ref_i, new_signature_ref_i);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// this is a double-indirect CP entry so it needs special handling
case JVM_CONSTANT_Fieldref: // fall through
case JVM_CONSTANT_InterfaceMethodref: // fall through
case JVM_CONSTANT_Methodref:
{
int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
merge_cp_p, merge_cp_length_p, THREAD);
int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
merge_cp_p, merge_cp_length_p, THREAD);
const char *entry_name;
switch (scratch_cp->tag_at(scratch_i).value()) {
case JVM_CONSTANT_Fieldref:
entry_name = "Fieldref";
(*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
new_name_and_type_ref_i);
break;
case JVM_CONSTANT_InterfaceMethodref:
entry_name = "IFMethodref";
(*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
new_klass_ref_i, new_name_and_type_ref_i);
break;
case JVM_CONSTANT_Methodref:
entry_name = "Methodref";
(*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
new_name_and_type_ref_i);
break;
default:
guarantee(false, "bad switch");
break;
}
if (klass_ref_i != new_klass_ref_i) {
RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
}
if (name_and_type_ref_i != new_name_and_type_ref_i) {
RC_TRACE(0x00080000,
("%s entry@%d name_and_type_index changed: %d to %d",
entry_name, *merge_cp_length_p, name_and_type_ref_i,
new_name_and_type_ref_i));
}
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// this is an indirect CP entry so it needs special handling
case JVM_CONSTANT_MethodType:
{
int ref_i = scratch_cp->method_type_index_at(scratch_i);
int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
if (new_ref_i != ref_i) {
RC_TRACE(0x00080000,
("MethodType entry@%d ref_index change: %d to %d",
*merge_cp_length_p, ref_i, new_ref_i));
}
(*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// this is an indirect CP entry so it needs special handling
case JVM_CONSTANT_MethodHandle:
{
int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
int ref_i = scratch_cp->method_handle_index_at(scratch_i);
int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
if (new_ref_i != ref_i) {
RC_TRACE(0x00080000,
("MethodHandle entry@%d ref_index change: %d to %d",
*merge_cp_length_p, ref_i, new_ref_i));
}
(*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// this is an indirect CP entry so it needs special handling
case JVM_CONSTANT_InvokeDynamic:
{
// Index of the bootstrap specifier in the operands array
int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
merge_cp_length_p, THREAD);
// The bootstrap method NameAndType_info index
int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
if (new_bs_i != old_bs_i) {
RC_TRACE(0x00080000,
("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
*merge_cp_length_p, old_bs_i, new_bs_i));
}
if (new_ref_i != old_ref_i) {
RC_TRACE(0x00080000,
("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
*merge_cp_length_p, old_ref_i, new_ref_i));
}
(*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
if (scratch_i != *merge_cp_length_p) {
// The new entry in *merge_cp_p is at a different index than
// the new entry in scratch_cp so we need to map the index values.
map_index(scratch_cp, scratch_i, *merge_cp_length_p);
}
(*merge_cp_length_p)++;
} break;
// At this stage, Class or UnresolvedClass could be here, but not
// ClassIndex
case JVM_CONSTANT_ClassIndex: // fall through
// Invalid is used as the tag for the second constant pool entry
// occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
// not be seen by itself.
case JVM_CONSTANT_Invalid: // fall through
// At this stage, String could be here, but not StringIndex
case JVM_CONSTANT_StringIndex: // fall through
// At this stage JVM_CONSTANT_UnresolvedClassInError should not be
// here
case JVM_CONSTANT_UnresolvedClassInError: // fall through
default:
{
// leave a breadcrumb
jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
ShouldNotReachHere();
} break;
} // end switch tag value
} // end append_entry()
int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
int new_ref_i = ref_i;
bool match = (ref_i < *merge_cp_length_p) &&
scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
if (!match) {
// forward reference in *merge_cp_p or not a direct match
int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
if (found_i != 0) {
guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
// Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
new_ref_i = found_i;
map_index(scratch_cp, ref_i, found_i);
} else {
// no match found so we have to append this entry to *merge_cp_p
append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
// The above call to append_entry() can only append one entry
// so the post call query of *merge_cp_length_p is only for
// the sake of consistency.
new_ref_i = *merge_cp_length_p - 1;
}
}
return new_ref_i;
} // end find_or_append_indirect_entry()
// Append a bootstrap specifier into the merge_cp operands that is semantically equal
// to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
// Recursively append new merge_cp entries referenced by the new bootstrap specifier.
void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
if (new_ref_i != old_ref_i) {
RC_TRACE(0x00080000,
("operands entry@%d bootstrap method ref_index change: %d to %d",
_operands_cur_length, old_ref_i, new_ref_i));
}
Array<u2>* merge_ops = (*merge_cp_p)->operands();
int new_bs_i = _operands_cur_length;
// We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
// However, the operand_offset_at(0) was set in the extend_operands() call.
int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
: (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
int argc = scratch_cp->operand_argument_count_at(old_bs_i);
ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
merge_ops->at_put(new_base++, new_ref_i);
merge_ops->at_put(new_base++, argc);
for (int i = 0; i < argc; i++) {
int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
merge_cp_length_p, THREAD);
merge_ops->at_put(new_base++, new_arg_ref_i);
if (new_arg_ref_i != old_arg_ref_i) {
RC_TRACE(0x00080000,
("operands entry@%d bootstrap method argument ref_index change: %d to %d",
_operands_cur_length, old_arg_ref_i, new_arg_ref_i));
}
}
if (old_bs_i != _operands_cur_length) {
// The bootstrap specifier in *merge_cp_p is at a different index than
// that in scratch_cp so we need to map the index values.
map_operand_index(old_bs_i, new_bs_i);
}
_operands_cur_length++;
} // end append_operand()
int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
int new_bs_i = old_bs_i; // bootstrap specifier index
bool match = (old_bs_i < _operands_cur_length) &&
scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
if (!match) {
// forward reference in *merge_cp_p or not a direct match
int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
_operands_cur_length, THREAD);
if (found_i != -1) {
guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
// found a matching operand somewhere else in *merge_cp_p so just need a mapping
new_bs_i = found_i;
map_operand_index(old_bs_i, found_i);
} else {
// no match found so we have to append this bootstrap specifier to *merge_cp_p
append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
new_bs_i = _operands_cur_length - 1;
}
}
return new_bs_i;
} // end find_or_append_operand()
void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
if (merge_cp->operands() == NULL) {
return;
}
// Shrink the merge_cp operands
merge_cp->shrink_operands(_operands_cur_length, CHECK);
if (RC_TRACE_ENABLED(0x00040000)) {
// don't want to loop unless we are tracing
int count = 0;
for (int i = 1; i < _operands_index_map_p->length(); i++) {
int value = _operands_index_map_p->at(i);
if (value != -1) {
RC_TRACE_WITH_THREAD(0x00040000, THREAD,
("operands_index_map[%d]: old=%d new=%d", count, i, value));
count++;
}
}
}
// Clean-up
_operands_index_map_p = NULL;
_operands_cur_length = 0;
_operands_index_map_count = 0;
} // end finalize_operands_merge()
jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
instanceKlassHandle the_class,
instanceKlassHandle scratch_class) {
int i;
// Check superclasses, or rather their names, since superclasses themselves can be
// requested to replace.
// Check for NULL superclass first since this might be java.lang.Object
if (the_class->super() != scratch_class->super() &&
(the_class->super() == NULL || scratch_class->super() == NULL ||
the_class->super()->name() !=
scratch_class->super()->name())) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
}
// Check if the number, names and order of directly implemented interfaces are the same.
// I think in principle we should just check if the sets of names of directly implemented
// interfaces are the same, i.e. the order of declaration (which, however, if changed in the
// .java file, also changes in .class file) should not matter. However, comparing sets is
// technically a bit more difficult, and, more importantly, I am not sure at present that the
// order of interfaces does not matter on the implementation level, i.e. that the VM does not
// rely on it somewhere.
Array<Klass*>* k_interfaces = the_class->local_interfaces();
Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
int n_intfs = k_interfaces->length();
if (n_intfs != k_new_interfaces->length()) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
}
for (i = 0; i < n_intfs; i++) {
if (k_interfaces->at(i)->name() !=
k_new_interfaces->at(i)->name()) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
}
}
// Check whether class is in the error init state.
if (the_class->is_in_error_state()) {
// TBD #5057930: special error code is needed in 1.6
return JVMTI_ERROR_INVALID_CLASS;
}
// Check whether class modifiers are the same.
jushort old_flags = (jushort) the_class->access_flags().get_flags();
jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
if (old_flags != new_flags) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
}
// Check if the number, names, types and order of fields declared in these classes
// are the same.
JavaFieldStream old_fs(the_class);
JavaFieldStream new_fs(scratch_class);
for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
// access
old_flags = old_fs.access_flags().as_short();
new_flags = new_fs.access_flags().as_short();
if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
}
// offset
if (old_fs.offset() != new_fs.offset()) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
}
// name and signature
Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
}
}
// If both streams aren't done then we have a differing number of
// fields.
if (!old_fs.done() || !new_fs.done()) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
}
// Do a parallel walk through the old and new methods. Detect
// cases where they match (exist in both), have been added in
// the new methods, or have been deleted (exist only in the
// old methods). The class file parser places methods in order
// by method name, but does not order overloaded methods by
// signature. In order to determine what fate befell the methods,
// this code places the overloaded new methods that have matching
// old methods in the same order as the old methods and places
// new overloaded methods at the end of overloaded methods of
// that name. The code for this order normalization is adapted
// from the algorithm used in InstanceKlass::find_method().
// Since we are swapping out of order entries as we find them,
// we only have to search forward through the overloaded methods.
// Methods which are added and have the same name as an existing
// method (but different signature) will be put at the end of
// the methods with that name, and the name mismatch code will
// handle them.
Array<Method*>* k_old_methods(the_class->methods());
Array<Method*>* k_new_methods(scratch_class->methods());
int n_old_methods = k_old_methods->length();
int n_new_methods = k_new_methods->length();
Thread* thread = Thread::current();
int ni = 0;
int oi = 0;
while (true) {
Method* k_old_method;
Method* k_new_method;
enum { matched, added, deleted, undetermined } method_was = undetermined;
if (oi >= n_old_methods) {
if (ni >= n_new_methods) {
break; // we've looked at everything, done
}
// New method at the end
k_new_method = k_new_methods->at(ni);
method_was = added;
} else if (ni >= n_new_methods) {
// Old method, at the end, is deleted
k_old_method = k_old_methods->at(oi);
method_was = deleted;
} else {
// There are more methods in both the old and new lists
k_old_method = k_old_methods->at(oi);
k_new_method = k_new_methods->at(ni);
if (k_old_method->name() != k_new_method->name()) {
// Methods are sorted by method name, so a mismatch means added
// or deleted
if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
method_was = added;
} else {
method_was = deleted;
}
} else if (k_old_method->signature() == k_new_method->signature()) {
// Both the name and signature match
method_was = matched;
} else {
// The name matches, but the signature doesn't, which means we have to
// search forward through the new overloaded methods.
int nj; // outside the loop for post-loop check
for (nj = ni + 1; nj < n_new_methods; nj++) {
Method* m = k_new_methods->at(nj);
if (k_old_method->name() != m->name()) {
// reached another method name so no more overloaded methods
method_was = deleted;
break;
}
if (k_old_method->signature() == m->signature()) {
// found a match so swap the methods
k_new_methods->at_put(ni, m);
k_new_methods->at_put(nj, k_new_method);
k_new_method = m;
method_was = matched;
break;
}
}
if (nj >= n_new_methods) {
// reached the end without a match; so method was deleted
method_was = deleted;
}
}
}
switch (method_was) {
case matched:
// methods match, be sure modifiers do too
old_flags = (jushort) k_old_method->access_flags().get_flags();
new_flags = (jushort) k_new_method->access_flags().get_flags();
if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
}
{
u2 new_num = k_new_method->method_idnum();
u2 old_num = k_old_method->method_idnum();
if (new_num != old_num) {
Method* idnum_owner = scratch_class->method_with_idnum(old_num);
if (idnum_owner != NULL) {
// There is already a method assigned this idnum -- switch them
idnum_owner->set_method_idnum(new_num);
}
k_new_method->set_method_idnum(old_num);
if (thread->has_pending_exception()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
}
}
}
RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
k_new_method->name_and_sig_as_C_string(), ni,
k_old_method->name_and_sig_as_C_string(), oi));
// advance to next pair of methods
++oi;
++ni;
break;
case added:
// method added, see if it is OK
new_flags = (jushort) k_new_method->access_flags().get_flags();
if ((new_flags & JVM_ACC_PRIVATE) == 0
// hack: private should be treated as final, but alas
|| (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
) {
// new methods must be private
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
}
{
u2 num = the_class->next_method_idnum();
if (num == ConstMethod::UNSET_IDNUM) {
// cannot add any more methods
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
}
u2 new_num = k_new_method->method_idnum();
Method* idnum_owner = scratch_class->method_with_idnum(num);
if (idnum_owner != NULL) {
// There is already a method assigned this idnum -- switch them
idnum_owner->set_method_idnum(new_num);
}
k_new_method->set_method_idnum(num);
if (thread->has_pending_exception()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
}
}
RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
k_new_method->name_and_sig_as_C_string(), ni));
++ni; // advance to next new method
break;
case deleted:
// method deleted, see if it is OK
old_flags = (jushort) k_old_method->access_flags().get_flags();
if ((old_flags & JVM_ACC_PRIVATE) == 0
// hack: private should be treated as final, but alas
|| (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
) {
// deleted methods must be private
return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
}
RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
k_old_method->name_and_sig_as_C_string(), oi));
++oi; // advance to next old method
break;
default:
ShouldNotReachHere();
}
}
return JVMTI_ERROR_NONE;
}
// Find new constant pool index value for old constant pool index value
// by seaching the index map. Returns zero (0) if there is no mapped
// value for the old constant pool index.
int VM_RedefineClasses::find_new_index(int old_index) {
if (_index_map_count == 0) {
// map is empty so nothing can be found
return 0;
}
if (old_index < 1 || old_index >= _index_map_p->length()) {
// The old_index is out of range so it is not mapped. This should
// not happen in regular constant pool merging use, but it can
// happen if a corrupt annotation is processed.
return 0;
}
int value = _index_map_p->at(old_index);
if (value == -1) {
// the old_index is not mapped
return 0;
}
return value;
} // end find_new_index()
// Find new bootstrap specifier index value for old bootstrap specifier index
// value by seaching the index map. Returns unused index (-1) if there is
// no mapped value for the old bootstrap specifier index.
int VM_RedefineClasses::find_new_operand_index(int old_index) {
if (_operands_index_map_count == 0) {
// map is empty so nothing can be found
return -1;
}
if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
// The old_index is out of range so it is not mapped.
// This should not happen in regular constant pool merging use.
return -1;
}
int value = _operands_index_map_p->at(old_index);
if (value == -1) {
// the old_index is not mapped
return -1;
}
return value;
} // end find_new_operand_index()
// Returns true if the current mismatch is due to a resolved/unresolved
// class pair. Otherwise, returns false.
bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
int index1, constantPoolHandle cp2, int index2) {
jbyte t1 = cp1->tag_at(index1).value();
if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
return false; // wrong entry type; not our special case
}
jbyte t2 = cp2->tag_at(index2).value();
if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
return false; // wrong entry type; not our special case
}
if (t1 == t2) {
return false; // not a mismatch; not our special case
}
char *s1 = cp1->klass_name_at(index1)->as_C_string();
char *s2 = cp2->klass_name_at(index2)->as_C_string();
if (strcmp(s1, s2) != 0) {
return false; // strings don't match; not our special case
}
return true; // made it through the gauntlet; this is our special case
} // end is_unresolved_class_mismatch()
jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
// For consistency allocate memory using os::malloc wrapper.
_scratch_classes = (Klass**)
os::malloc(sizeof(Klass*) * _class_count, mtClass);
if (_scratch_classes == NULL) {
return JVMTI_ERROR_OUT_OF_MEMORY;
}
// Zero initialize the _scratch_classes array.
for (int i = 0; i < _class_count; i++) {
_scratch_classes[i] = NULL;
}
ResourceMark rm(THREAD);
JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
// state can only be NULL if the current thread is exiting which
// should not happen since we're trying to do a RedefineClasses
guarantee(state != NULL, "exiting thread calling load_new_class_versions");
for (int i = 0; i < _class_count; i++) {
// Create HandleMark so that any handles created while loading new class
// versions are deleted. Constant pools are deallocated while merging
// constant pools
HandleMark hm(THREAD);
oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
// classes for primitives cannot be redefined
if (!is_modifiable_class(mirror)) {
return JVMTI_ERROR_UNMODIFIABLE_CLASS;
}
Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
Symbol* the_class_sym = the_class->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000001, THREAD,
("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
the_class->external_name(), _class_load_kind,
os::available_memory() >> 10));
ClassFileStream st((u1*) _class_defs[i].class_bytes,
_class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
// Parse the stream.
Handle the_class_loader(THREAD, the_class->class_loader());
Handle protection_domain(THREAD, the_class->protection_domain());
// Set redefined class handle in JvmtiThreadState class.
// This redefined class is sent to agent event handler for class file
// load hook event.
state->set_class_being_redefined(&the_class, _class_load_kind);
Klass* k = SystemDictionary::parse_stream(the_class_sym,
the_class_loader,
protection_domain,
&st,
THREAD);
// Clear class_being_redefined just to be sure.
state->clear_class_being_redefined();
// TODO: if this is retransform, and nothing changed we can skip it
instanceKlassHandle scratch_class (THREAD, k);
// Need to clean up allocated InstanceKlass if there's an error so assign
// the result here. Caller deallocates all the scratch classes in case of
// an error.
_scratch_classes[i] = k;
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
return JVMTI_ERROR_UNSUPPORTED_VERSION;
} else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
return JVMTI_ERROR_INVALID_CLASS_FORMAT;
} else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
} else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
// The message will be "XXX (wrong name: YYY)"
return JVMTI_ERROR_NAMES_DONT_MATCH;
} else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else { // Just in case more exceptions can be thrown..
return JVMTI_ERROR_FAILS_VERIFICATION;
}
}
// Ensure class is linked before redefine
if (!the_class->is_linked()) {
the_class->link_class(THREAD);
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else {
return JVMTI_ERROR_INTERNAL;
}
}
}
// Do the validity checks in compare_and_normalize_class_versions()
// before verifying the byte codes. By doing these checks first, we
// limit the number of functions that require redirection from
// the_class to scratch_class. In particular, we don't have to
// modify JNI GetSuperclass() and thus won't change its performance.
jvmtiError res = compare_and_normalize_class_versions(the_class,
scratch_class);
if (res != JVMTI_ERROR_NONE) {
return res;
}
// verify what the caller passed us
{
// The bug 6214132 caused the verification to fail.
// Information about the_class and scratch_class is temporarily
// recorded into jvmtiThreadState. This data is used to redirect
// the_class to scratch_class in the JVM_* functions called by the
// verifier. Please, refer to jvmtiThreadState.hpp for the detailed
// description.
RedefineVerifyMark rvm(&the_class, &scratch_class, state);
Verifier::verify(
scratch_class, Verifier::ThrowException, true, THREAD);
}
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD,
("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else {
// tell the caller the bytecodes are bad
return JVMTI_ERROR_FAILS_VERIFICATION;
}
}
res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD,
("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else {
return JVMTI_ERROR_INTERNAL;
}
}
if (VerifyMergedCPBytecodes) {
// verify what we have done during constant pool merging
{
RedefineVerifyMark rvm(&the_class, &scratch_class, state);
Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
}
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD,
("verify_byte_codes post merge-CP exception: '%s'",
ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else {
// tell the caller that constant pool merging screwed up
return JVMTI_ERROR_INTERNAL;
}
}
}
Rewriter::rewrite(scratch_class, THREAD);
if (!HAS_PENDING_EXCEPTION) {
scratch_class->link_methods(THREAD);
}
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD,
("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()));
CLEAR_PENDING_EXCEPTION;
if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
return JVMTI_ERROR_OUT_OF_MEMORY;
} else {
return JVMTI_ERROR_INTERNAL;
}
}
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000001, THREAD,
("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
the_class->external_name(), os::available_memory() >> 10));
}
return JVMTI_ERROR_NONE;
}
// Map old_index to new_index as needed. scratch_cp is only needed
// for RC_TRACE() calls.
void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
int old_index, int new_index) {
if (find_new_index(old_index) != 0) {
// old_index is already mapped
return;
}
if (old_index == new_index) {
// no mapping is needed
return;
}
_index_map_p->at_put(old_index, new_index);
_index_map_count++;
RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
scratch_cp->tag_at(old_index).value(), old_index, new_index));
} // end map_index()
// Map old_index to new_index as needed.
void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
if (find_new_operand_index(old_index) != -1) {
// old_index is already mapped
return;
}
if (old_index == new_index) {
// no mapping is needed
return;
}
_operands_index_map_p->at_put(old_index, new_index);
_operands_index_map_count++;
RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
} // end map_index()
// Merge old_cp and scratch_cp and return the results of the merge via
// merge_cp_p. The number of entries in *merge_cp_p is returned via
// merge_cp_length_p. The entries in old_cp occupy the same locations
// in *merge_cp_p. Also creates a map of indices from entries in
// scratch_cp to the corresponding entry in *merge_cp_p. Index map
// entries are only created for entries in scratch_cp that occupy a
// different location in *merged_cp_p.
bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
int *merge_cp_length_p, TRAPS) {
if (merge_cp_p == NULL) {
assert(false, "caller must provide scratch constantPool");
return false; // robustness
}
if (merge_cp_length_p == NULL) {
assert(false, "caller must provide scratch CP length");
return false; // robustness
}
// Worst case we need old_cp->length() + scratch_cp()->length(),
// but the caller might be smart so make sure we have at least
// the minimum.
if ((*merge_cp_p)->length() < old_cp->length()) {
assert(false, "merge area too small");
return false; // robustness
}
RC_TRACE_WITH_THREAD(0x00010000, THREAD,
("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
scratch_cp->length()));
{
// Pass 0:
// The old_cp is copied to *merge_cp_p; this means that any code
// using old_cp does not have to change. This work looks like a
// perfect fit for ConstantPool*::copy_cp_to(), but we need to
// handle one special case:
// - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
// This will make verification happy.
int old_i; // index into old_cp
// index zero (0) is not used in constantPools
for (old_i = 1; old_i < old_cp->length(); old_i++) {
// leave debugging crumb
jbyte old_tag = old_cp->tag_at(old_i).value();
switch (old_tag) {
case JVM_CONSTANT_Class:
case JVM_CONSTANT_UnresolvedClass:
// revert the copy to JVM_CONSTANT_UnresolvedClass
// May be resolving while calling this so do the same for
// JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
(*merge_cp_p)->unresolved_klass_at_put(old_i,
old_cp->klass_name_at(old_i));
break;
case JVM_CONSTANT_Double:
case JVM_CONSTANT_Long:
// just copy the entry to *merge_cp_p, but double and long take
// two constant pool entries
ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
old_i++;
break;
default:
// just copy the entry to *merge_cp_p
ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
break;
}
} // end for each old_cp entry
ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
(*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
// We don't need to sanity check that *merge_cp_length_p is within
// *merge_cp_p bounds since we have the minimum on-entry check above.
(*merge_cp_length_p) = old_i;
}
// merge_cp_len should be the same as old_cp->length() at this point
// so this trace message is really a "warm-and-breathing" message.
RC_TRACE_WITH_THREAD(0x00020000, THREAD,
("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
int scratch_i; // index into scratch_cp
{
// Pass 1a:
// Compare scratch_cp entries to the old_cp entries that we have
// already copied to *merge_cp_p. In this pass, we are eliminating
// exact duplicates (matching entry at same index) so we only
// compare entries in the common indice range.
int increment = 1;
int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
switch (scratch_cp->tag_at(scratch_i).value()) {
case JVM_CONSTANT_Double:
case JVM_CONSTANT_Long:
// double and long take two constant pool entries
increment = 2;
break;
default:
increment = 1;
break;
}
bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
scratch_i, CHECK_0);
if (match) {
// found a match at the same index so nothing more to do
continue;
} else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
*merge_cp_p, scratch_i)) {
// The mismatch in compare_entry_to() above is because of a
// resolved versus unresolved class entry at the same index
// with the same string value. Since Pass 0 reverted any
// class entries to unresolved class entries in *merge_cp_p,
// we go with the unresolved class entry.
continue;
}
int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
CHECK_0);
if (found_i != 0) {
guarantee(found_i != scratch_i,
"compare_entry_to() and find_matching_entry() do not agree");
// Found a matching entry somewhere else in *merge_cp_p so
// just need a mapping entry.
map_index(scratch_cp, scratch_i, found_i);
continue;
}
// The find_matching_entry() call above could fail to find a match
// due to a resolved versus unresolved class or string entry situation
// like we solved above with the is_unresolved_*_mismatch() calls.
// However, we would have to call is_unresolved_*_mismatch() over
// all of *merge_cp_p (potentially) and that doesn't seem to be
// worth the time.
// No match found so we have to append this entry and any unique
// referenced entries to *merge_cp_p.
append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
CHECK_0);
}
}
RC_TRACE_WITH_THREAD(0x00020000, THREAD,
("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
*merge_cp_length_p, scratch_i, _index_map_count));
if (scratch_i < scratch_cp->length()) {
// Pass 1b:
// old_cp is smaller than scratch_cp so there are entries in
// scratch_cp that we have not yet processed. We take care of
// those now.
int increment = 1;
for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
switch (scratch_cp->tag_at(scratch_i).value()) {
case JVM_CONSTANT_Double:
case JVM_CONSTANT_Long:
// double and long take two constant pool entries
increment = 2;
break;
default:
increment = 1;
break;
}
int found_i =
scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
if (found_i != 0) {
// Found a matching entry somewhere else in *merge_cp_p so
// just need a mapping entry.
map_index(scratch_cp, scratch_i, found_i);
continue;
}
// No match found so we have to append this entry and any unique
// referenced entries to *merge_cp_p.
append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
CHECK_0);
}
RC_TRACE_WITH_THREAD(0x00020000, THREAD,
("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
*merge_cp_length_p, scratch_i, _index_map_count));
}
finalize_operands_merge(*merge_cp_p, THREAD);
return true;
} // end merge_constant_pools()
// Scoped object to clean up the constant pool(s) created for merging
class MergeCPCleaner {
ClassLoaderData* _loader_data;
ConstantPool* _cp;
ConstantPool* _scratch_cp;
public:
MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
_loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
~MergeCPCleaner() {
_loader_data->add_to_deallocate_list(_cp);
if (_scratch_cp != NULL) {
_loader_data->add_to_deallocate_list(_scratch_cp);
}
}
void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
};
// Merge constant pools between the_class and scratch_class and
// potentially rewrite bytecodes in scratch_class to use the merged
// constant pool.
jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
instanceKlassHandle the_class, instanceKlassHandle scratch_class,
TRAPS) {
// worst case merged constant pool length is old and new combined
int merge_cp_length = the_class->constants()->length()
+ scratch_class->constants()->length();
// Constant pools are not easily reused so we allocate a new one
// each time.
// merge_cp is created unsafe for concurrent GC processing. It
// should be marked safe before discarding it. Even though
// garbage, if it crosses a card boundary, it may be scanned
// in order to find the start of the first complete object on the card.
ClassLoaderData* loader_data = the_class->class_loader_data();
ConstantPool* merge_cp_oop =
ConstantPool::allocate(loader_data,
merge_cp_length,
CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
HandleMark hm(THREAD); // make sure handles are cleared before
// MergeCPCleaner clears out merge_cp_oop
constantPoolHandle merge_cp(THREAD, merge_cp_oop);
// Get constants() from the old class because it could have been rewritten
// while we were at a safepoint allocating a new constant pool.
constantPoolHandle old_cp(THREAD, the_class->constants());
constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
// If the length changed, the class was redefined out from under us. Return
// an error.
if (merge_cp_length != the_class->constants()->length()
+ scratch_class->constants()->length()) {
return JVMTI_ERROR_INTERNAL;
}
// Update the version number of the constant pool
merge_cp->increment_and_save_version(old_cp->version());
ResourceMark rm(THREAD);
_index_map_count = 0;
_index_map_p = new intArray(scratch_cp->length(), -1);
_operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
_operands_index_map_count = 0;
_operands_index_map_p = new intArray(
ConstantPool::operand_array_length(scratch_cp->operands()), -1);
// reference to the cp holder is needed for copy_operands()
merge_cp->set_pool_holder(scratch_class());
bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
&merge_cp_length, THREAD);
merge_cp->set_pool_holder(NULL);
if (!result) {
// The merge can fail due to memory allocation failure or due
// to robustness checks.
return JVMTI_ERROR_INTERNAL;
}
RC_TRACE_WITH_THREAD(0x00010000, THREAD,
("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
if (_index_map_count == 0) {
// there is nothing to map between the new and merged constant pools
if (old_cp->length() == scratch_cp->length()) {
// The old and new constant pools are the same length and the
// index map is empty. This means that the three constant pools
// are equivalent (but not the same). Unfortunately, the new
// constant pool has not gone through link resolution nor have
// the new class bytecodes gone through constant pool cache
// rewriting so we can't use the old constant pool with the new
// class.
// toss the merged constant pool at return
} else if (old_cp->length() < scratch_cp->length()) {
// The old constant pool has fewer entries than the new constant
// pool and the index map is empty. This means the new constant
// pool is a superset of the old constant pool. However, the old
// class bytecodes have already gone through constant pool cache
// rewriting so we can't use the new constant pool with the old
// class.
// toss the merged constant pool at return
} else {
// The old constant pool has more entries than the new constant
// pool and the index map is empty. This means that both the old
// and merged constant pools are supersets of the new constant
// pool.
// Replace the new constant pool with a shrunken copy of the
// merged constant pool
set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
// The new constant pool replaces scratch_cp so have cleaner clean it up.
// It can't be cleaned up while there are handles to it.
cp_cleaner.add_scratch_cp(scratch_cp());
}
} else {
if (RC_TRACE_ENABLED(0x00040000)) {
// don't want to loop unless we are tracing
int count = 0;
for (int i = 1; i < _index_map_p->length(); i++) {
int value = _index_map_p->at(i);
if (value != -1) {
RC_TRACE_WITH_THREAD(0x00040000, THREAD,
("index_map[%d]: old=%d new=%d", count, i, value));
count++;
}
}
}
// We have entries mapped between the new and merged constant pools
// so we have to rewrite some constant pool references.
if (!rewrite_cp_refs(scratch_class, THREAD)) {
return JVMTI_ERROR_INTERNAL;
}
// Replace the new constant pool with a shrunken copy of the
// merged constant pool so now the rewritten bytecodes have
// valid references; the previous new constant pool will get
// GCed.
set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
// The new constant pool replaces scratch_cp so have cleaner clean it up.
// It can't be cleaned up while there are handles to it.
cp_cleaner.add_scratch_cp(scratch_cp());
}
return JVMTI_ERROR_NONE;
} // end merge_cp_and_rewrite()
// Rewrite constant pool references in klass scratch_class.
bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
TRAPS) {
// rewrite constant pool references in the methods:
if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite constant pool references in the class_annotations:
if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite constant pool references in the fields_annotations:
if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite constant pool references in the methods_annotations:
if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite constant pool references in the methods_parameter_annotations:
if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite constant pool references in the methods_default_annotations:
if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
THREAD)) {
// propagate failure back to caller
return false;
}
// rewrite source file name index:
u2 source_file_name_idx = scratch_class->source_file_name_index();
if (source_file_name_idx != 0) {
u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
if (new_source_file_name_idx != 0) {
scratch_class->set_source_file_name_index(new_source_file_name_idx);
}
}
// rewrite class generic signature index:
u2 generic_signature_index = scratch_class->generic_signature_index();
if (generic_signature_index != 0) {
u2 new_generic_signature_index = find_new_index(generic_signature_index);
if (new_generic_signature_index != 0) {
scratch_class->set_generic_signature_index(new_generic_signature_index);
}
}
return true;
} // end rewrite_cp_refs()
// Rewrite constant pool references in the methods.
bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
instanceKlassHandle scratch_class, TRAPS) {
Array<Method*>* methods = scratch_class->methods();
if (methods == NULL || methods->length() == 0) {
// no methods so nothing to do
return true;
}
// rewrite constant pool references in the methods:
for (int i = methods->length() - 1; i >= 0; i--) {
methodHandle method(THREAD, methods->at(i));
methodHandle new_method;
rewrite_cp_refs_in_method(method, &new_method, THREAD);
if (!new_method.is_null()) {
// the method has been replaced so save the new method version
// even in the case of an exception. original method is on the
// deallocation list.
methods->at_put(i, new_method());
}
if (HAS_PENDING_EXCEPTION) {
Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
// RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000002, THREAD,
("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()));
// Need to clear pending exception here as the super caller sets
// the JVMTI_ERROR_INTERNAL if the returned value is false.
CLEAR_PENDING_EXCEPTION;
return false;
}
}
return true;
}
// Rewrite constant pool references in the specific method. This code
// was adapted from Rewriter::rewrite_method().
void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
methodHandle *new_method_p, TRAPS) {
*new_method_p = methodHandle(); // default is no new method
// We cache a pointer to the bytecodes here in code_base. If GC
// moves the Method*, then the bytecodes will also move which
// will likely cause a crash. We create a No_Safepoint_Verifier
// object to detect whether we pass a possible safepoint in this
// code block.
No_Safepoint_Verifier nsv;
// Bytecodes and their length
address code_base = method->code_base();
int code_length = method->code_size();
int bc_length;
for (int bci = 0; bci < code_length; bci += bc_length) {
address bcp = code_base + bci;
Bytecodes::Code c = (Bytecodes::Code)(*bcp);
bc_length = Bytecodes::length_for(c);
if (bc_length == 0) {
// More complicated bytecodes report a length of zero so
// we have to try again a slightly different way.
bc_length = Bytecodes::length_at(method(), bcp);
}
assert(bc_length != 0, "impossible bytecode length");
switch (c) {
case Bytecodes::_ldc:
{
int cp_index = *(bcp + 1);
int new_index = find_new_index(cp_index);
if (StressLdcRewrite && new_index == 0) {
// If we are stressing ldc -> ldc_w rewriting, then we
// always need a new_index value.
new_index = cp_index;
}
if (new_index != 0) {
// the original index is mapped so we have more work to do
if (!StressLdcRewrite && new_index <= max_jubyte) {
// The new value can still use ldc instead of ldc_w
// unless we are trying to stress ldc -> ldc_w rewriting
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
bcp, cp_index, new_index));
*(bcp + 1) = new_index;
} else {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
Bytecodes::name(c), bcp, cp_index, new_index));
// the new value needs ldc_w instead of ldc
u_char inst_buffer[4]; // max instruction size is 4 bytes
bcp = (address)inst_buffer;
// construct new instruction sequence
*bcp = Bytecodes::_ldc_w;
bcp++;
// Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
// See comment below for difference between put_Java_u2()
// and put_native_u2().
Bytes::put_Java_u2(bcp, new_index);
Relocator rc(method, NULL /* no RelocatorListener needed */);
methodHandle m;
{
Pause_No_Safepoint_Verifier pnsv(&nsv);
// ldc is 2 bytes and ldc_w is 3 bytes
m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
}
// return the new method so that the caller can update
// the containing class
*new_method_p = method = m;
// switch our bytecode processing loop from the old method
// to the new method
code_base = method->code_base();
code_length = method->code_size();
bcp = code_base + bci;
c = (Bytecodes::Code)(*bcp);
bc_length = Bytecodes::length_for(c);
assert(bc_length != 0, "sanity check");
} // end we need ldc_w instead of ldc
} // end if there is a mapped index
} break;
// these bytecodes have a two-byte constant pool index
case Bytecodes::_anewarray : // fall through
case Bytecodes::_checkcast : // fall through
case Bytecodes::_getfield : // fall through
case Bytecodes::_getstatic : // fall through
case Bytecodes::_instanceof : // fall through
case Bytecodes::_invokedynamic : // fall through
case Bytecodes::_invokeinterface: // fall through
case Bytecodes::_invokespecial : // fall through
case Bytecodes::_invokestatic : // fall through
case Bytecodes::_invokevirtual : // fall through
case Bytecodes::_ldc_w : // fall through
case Bytecodes::_ldc2_w : // fall through
case Bytecodes::_multianewarray : // fall through
case Bytecodes::_new : // fall through
case Bytecodes::_putfield : // fall through
case Bytecodes::_putstatic :
{
address p = bcp + 1;
int cp_index = Bytes::get_Java_u2(p);
int new_index = find_new_index(cp_index);
if (new_index != 0) {
// the original index is mapped so update w/ new value
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
bcp, cp_index, new_index));
// Rewriter::rewrite_method() uses put_native_u2() in this
// situation because it is reusing the constant pool index
// location for a native index into the ConstantPoolCache.
// Since we are updating the constant pool index prior to
// verification and ConstantPoolCache initialization, we
// need to keep the new index in Java byte order.
Bytes::put_Java_u2(p, new_index);
}
} break;
}
} // end for each bytecode
// We also need to rewrite the parameter name indexes, if there is
// method parameter data present
if(method->has_method_parameters()) {
const int len = method->method_parameters_length();
MethodParametersElement* elem = method->method_parameters_start();
for (int i = 0; i < len; i++) {
const u2 cp_index = elem[i].name_cp_index;
const u2 new_cp_index = find_new_index(cp_index);
if (new_cp_index != 0) {
elem[i].name_cp_index = new_cp_index;
}
}
}
} // end rewrite_cp_refs_in_method()
// Rewrite constant pool references in the class_annotations field.
bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
instanceKlassHandle scratch_class, TRAPS) {
AnnotationArray* class_annotations = scratch_class->class_annotations();
if (class_annotations == NULL || class_annotations->length() == 0) {
// no class_annotations so nothing to do
return true;
}
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("class_annotations length=%d", class_annotations->length()));
int byte_i = 0; // byte index into class_annotations
return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
THREAD);
}
// Rewrite constant pool references in an annotations typeArray. This
// "structure" is adapted from the RuntimeVisibleAnnotations_attribute
// that is described in section 4.8.15 of the 2nd-edition of the VM spec:
//
// annotations_typeArray {
// u2 num_annotations;
// annotation annotations[num_annotations];
// }
//
bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
if ((byte_i_ref + 2) > annotations_typeArray->length()) {
// not enough room for num_annotations field
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for num_annotations field"));
return false;
}
u2 num_annotations = Bytes::get_Java_u2((address)
annotations_typeArray->adr_at(byte_i_ref));
byte_i_ref += 2;
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("num_annotations=%d", num_annotations));
int calc_num_annotations = 0;
for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
byte_i_ref, THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad annotation_struct at %d", calc_num_annotations));
// propagate failure back to caller
return false;
}
}
assert(num_annotations == calc_num_annotations, "sanity check");
return true;
} // end rewrite_cp_refs_in_annotations_typeArray()
// Rewrite constant pool references in the annotation struct portion of
// an annotations_typeArray. This "structure" is from section 4.8.15 of
// the 2nd-edition of the VM spec:
//
// struct annotation {
// u2 type_index;
// u2 num_element_value_pairs;
// {
// u2 element_name_index;
// element_value value;
// } element_value_pairs[num_element_value_pairs];
// }
//
bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
// not enough room for smallest annotation_struct
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for annotation_struct"));
return false;
}
u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
byte_i_ref, "mapped old type_index=%d", THREAD);
u2 num_element_value_pairs = Bytes::get_Java_u2((address)
annotations_typeArray->adr_at(byte_i_ref));
byte_i_ref += 2;
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("type_index=%d num_element_value_pairs=%d", type_index,
num_element_value_pairs));
int calc_num_element_value_pairs = 0;
for (; calc_num_element_value_pairs < num_element_value_pairs;
calc_num_element_value_pairs++) {
if ((byte_i_ref + 2) > annotations_typeArray->length()) {
// not enough room for another element_name_index, let alone
// the rest of another component
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for element_name_index"));
return false;
}
u2 element_name_index = rewrite_cp_ref_in_annotation_data(
annotations_typeArray, byte_i_ref,
"mapped old element_name_index=%d", THREAD);
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("element_name_index=%d", element_name_index));
if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
byte_i_ref, THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad element_value at %d", calc_num_element_value_pairs));
// propagate failure back to caller
return false;
}
} // end for each component
assert(num_element_value_pairs == calc_num_element_value_pairs,
"sanity check");
return true;
} // end rewrite_cp_refs_in_annotation_struct()
// Rewrite a constant pool reference at the current position in
// annotations_typeArray if needed. Returns the original constant
// pool reference if a rewrite was not needed or the new constant
// pool reference if a rewrite was needed.
u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
AnnotationArray* annotations_typeArray, int &byte_i_ref,
const char * trace_mesg, TRAPS) {
address cp_index_addr = (address)
annotations_typeArray->adr_at(byte_i_ref);
u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
u2 new_cp_index = find_new_index(old_cp_index);
if (new_cp_index != 0) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
Bytes::put_Java_u2(cp_index_addr, new_cp_index);
old_cp_index = new_cp_index;
}
byte_i_ref += 2;
return old_cp_index;
}
// Rewrite constant pool references in the element_value portion of an
// annotations_typeArray. This "structure" is from section 4.8.15.1 of
// the 2nd-edition of the VM spec:
//
// struct element_value {
// u1 tag;
// union {
// u2 const_value_index;
// {
// u2 type_name_index;
// u2 const_name_index;
// } enum_const_value;
// u2 class_info_index;
// annotation annotation_value;
// struct {
// u2 num_values;
// element_value values[num_values];
// } array_value;
// } value;
// }
//
bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
if ((byte_i_ref + 1) > annotations_typeArray->length()) {
// not enough room for a tag let alone the rest of an element_value
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a tag"));
return false;
}
u1 tag = annotations_typeArray->at(byte_i_ref);
byte_i_ref++;
RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
switch (tag) {
// These BaseType tag values are from Table 4.2 in VM spec:
case 'B': // byte
case 'C': // char
case 'D': // double
case 'F': // float
case 'I': // int
case 'J': // long
case 'S': // short
case 'Z': // boolean
// The remaining tag values are from Table 4.8 in the 2nd-edition of
// the VM spec:
case 's':
{
// For the above tag values (including the BaseType values),
// value.const_value_index is right union field.
if ((byte_i_ref + 2) > annotations_typeArray->length()) {
// not enough room for a const_value_index
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a const_value_index"));
return false;
}
u2 const_value_index = rewrite_cp_ref_in_annotation_data(
annotations_typeArray, byte_i_ref,
"mapped old const_value_index=%d", THREAD);
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("const_value_index=%d", const_value_index));
} break;
case 'e':
{
// for the above tag value, value.enum_const_value is right union field
if ((byte_i_ref + 4) > annotations_typeArray->length()) {
// not enough room for a enum_const_value
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a enum_const_value"));
return false;
}
u2 type_name_index = rewrite_cp_ref_in_annotation_data(
annotations_typeArray, byte_i_ref,
"mapped old type_name_index=%d", THREAD);
u2 const_name_index = rewrite_cp_ref_in_annotation_data(
annotations_typeArray, byte_i_ref,
"mapped old const_name_index=%d", THREAD);
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("type_name_index=%d const_name_index=%d", type_name_index,
const_name_index));
} break;
case 'c':
{
// for the above tag value, value.class_info_index is right union field
if ((byte_i_ref + 2) > annotations_typeArray->length()) {
// not enough room for a class_info_index
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a class_info_index"));
return false;
}
u2 class_info_index = rewrite_cp_ref_in_annotation_data(
annotations_typeArray, byte_i_ref,
"mapped old class_info_index=%d", THREAD);
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("class_info_index=%d", class_info_index));
} break;
case '@':
// For the above tag value, value.attr_value is the right union
// field. This is a nested annotation.
if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
byte_i_ref, THREAD)) {
// propagate failure back to caller
return false;
}
break;
case '[':
{
if ((byte_i_ref + 2) > annotations_typeArray->length()) {
// not enough room for a num_values field
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a num_values field"));
return false;
}
// For the above tag value, value.array_value is the right union
// field. This is an array of nested element_value.
u2 num_values = Bytes::get_Java_u2((address)
annotations_typeArray->adr_at(byte_i_ref));
byte_i_ref += 2;
RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
int calc_num_values = 0;
for (; calc_num_values < num_values; calc_num_values++) {
if (!rewrite_cp_refs_in_element_value(
annotations_typeArray, byte_i_ref, THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad nested element_value at %d", calc_num_values));
// propagate failure back to caller
return false;
}
}
assert(num_values == calc_num_values, "sanity check");
} break;
default:
RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
return false;
} // end decode tag field
return true;
} // end rewrite_cp_refs_in_element_value()
// Rewrite constant pool references in a fields_annotations field.
bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
instanceKlassHandle scratch_class, TRAPS) {
Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
if (fields_annotations == NULL || fields_annotations->length() == 0) {
// no fields_annotations so nothing to do
return true;
}
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("fields_annotations length=%d", fields_annotations->length()));
for (int i = 0; i < fields_annotations->length(); i++) {
AnnotationArray* field_annotations = fields_annotations->at(i);
if (field_annotations == NULL || field_annotations->length() == 0) {
// this field does not have any annotations so skip it
continue;
}
int byte_i = 0; // byte index into field_annotations
if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad field_annotations at %d", i));
// propagate failure back to caller
return false;
}
}
return true;
} // end rewrite_cp_refs_in_fields_annotations()
// Rewrite constant pool references in a methods_annotations field.
bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
instanceKlassHandle scratch_class, TRAPS) {
for (int i = 0; i < scratch_class->methods()->length(); i++) {
Method* m = scratch_class->methods()->at(i);
AnnotationArray* method_annotations = m->constMethod()->method_annotations();
if (method_annotations == NULL || method_annotations->length() == 0) {
// this method does not have any annotations so skip it
continue;
}
int byte_i = 0; // byte index into method_annotations
if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad method_annotations at %d", i));
// propagate failure back to caller
return false;
}
}
return true;
} // end rewrite_cp_refs_in_methods_annotations()
// Rewrite constant pool references in a methods_parameter_annotations
// field. This "structure" is adapted from the
// RuntimeVisibleParameterAnnotations_attribute described in section
// 4.8.17 of the 2nd-edition of the VM spec:
//
// methods_parameter_annotations_typeArray {
// u1 num_parameters;
// {
// u2 num_annotations;
// annotation annotations[num_annotations];
// } parameter_annotations[num_parameters];
// }
//
bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
instanceKlassHandle scratch_class, TRAPS) {
for (int i = 0; i < scratch_class->methods()->length(); i++) {
Method* m = scratch_class->methods()->at(i);
AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
if (method_parameter_annotations == NULL
|| method_parameter_annotations->length() == 0) {
// this method does not have any parameter annotations so skip it
continue;
}
if (method_parameter_annotations->length() < 1) {
// not enough room for a num_parameters field
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("length() is too small for a num_parameters field at %d", i));
return false;
}
int byte_i = 0; // byte index into method_parameter_annotations
u1 num_parameters = method_parameter_annotations->at(byte_i);
byte_i++;
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("num_parameters=%d", num_parameters));
int calc_num_parameters = 0;
for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
if (!rewrite_cp_refs_in_annotations_typeArray(
method_parameter_annotations, byte_i, THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad method_parameter_annotations at %d", calc_num_parameters));
// propagate failure back to caller
return false;
}
}
assert(num_parameters == calc_num_parameters, "sanity check");
}
return true;
} // end rewrite_cp_refs_in_methods_parameter_annotations()
// Rewrite constant pool references in a methods_default_annotations
// field. This "structure" is adapted from the AnnotationDefault_attribute
// that is described in section 4.8.19 of the 2nd-edition of the VM spec:
//
// methods_default_annotations_typeArray {
// element_value default_value;
// }
//
bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
instanceKlassHandle scratch_class, TRAPS) {
for (int i = 0; i < scratch_class->methods()->length(); i++) {
Method* m = scratch_class->methods()->at(i);
AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
if (method_default_annotations == NULL
|| method_default_annotations->length() == 0) {
// this method does not have any default annotations so skip it
continue;
}
int byte_i = 0; // byte index into method_default_annotations
if (!rewrite_cp_refs_in_element_value(
method_default_annotations, byte_i, THREAD)) {
RC_TRACE_WITH_THREAD(0x02000000, THREAD,
("bad default element_value at %d", i));
// propagate failure back to caller
return false;
}
}
return true;
} // end rewrite_cp_refs_in_methods_default_annotations()
// Rewrite constant pool references in the method's stackmap table.
// These "structures" are adapted from the StackMapTable_attribute that
// is described in section 4.8.4 of the 6.0 version of the VM spec
// (dated 2005.10.26):
// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
//
// stack_map {
// u2 number_of_entries;
// stack_map_frame entries[number_of_entries];
// }
//
void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
methodHandle method, TRAPS) {
if (!method->has_stackmap_table()) {
return;
}
AnnotationArray* stackmap_data = method->stackmap_data();
address stackmap_p = (address)stackmap_data->adr_at(0);
address stackmap_end = stackmap_p + stackmap_data->length();
assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
stackmap_p += 2;
RC_TRACE_WITH_THREAD(0x04000000, THREAD,
("number_of_entries=%u", number_of_entries));
// walk through each stack_map_frame
u2 calc_number_of_entries = 0;
for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
// The stack_map_frame structure is a u1 frame_type followed by
// 0 or more bytes of data:
//
// union stack_map_frame {
// same_frame;
// same_locals_1_stack_item_frame;
// same_locals_1_stack_item_frame_extended;
// chop_frame;
// same_frame_extended;
// append_frame;
// full_frame;
// }
assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
// The Linux compiler does not like frame_type to be u1 or u2. It
// issues the following warning for the first if-statement below:
//
// "warning: comparison is always true due to limited range of data type"
//
u4 frame_type = *stackmap_p;
stackmap_p++;
// same_frame {
// u1 frame_type = SAME; /* 0-63 */
// }
if (frame_type >= 0 && frame_type <= 63) {
// nothing more to do for same_frame
}
// same_locals_1_stack_item_frame {
// u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
// verification_type_info stack[1];
// }
else if (frame_type >= 64 && frame_type <= 127) {
rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
calc_number_of_entries, frame_type, THREAD);
}
// reserved for future use
else if (frame_type >= 128 && frame_type <= 246) {
// nothing more to do for reserved frame_types
}
// same_locals_1_stack_item_frame_extended {
// u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
// u2 offset_delta;
// verification_type_info stack[1];
// }
else if (frame_type == 247) {
stackmap_p += 2;
rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
calc_number_of_entries, frame_type, THREAD);
}
// chop_frame {
// u1 frame_type = CHOP; /* 248-250 */
// u2 offset_delta;
// }
else if (frame_type >= 248 && frame_type <= 250) {
stackmap_p += 2;
}
// same_frame_extended {
// u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
// u2 offset_delta;
// }
else if (frame_type == 251) {
stackmap_p += 2;
}
// append_frame {
// u1 frame_type = APPEND; /* 252-254 */
// u2 offset_delta;
// verification_type_info locals[frame_type - 251];
// }
else if (frame_type >= 252 && frame_type <= 254) {
assert(stackmap_p + 2 <= stackmap_end,
"no room for offset_delta");
stackmap_p += 2;
u1 len = frame_type - 251;
for (u1 i = 0; i < len; i++) {
rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
calc_number_of_entries, frame_type, THREAD);
}
}
// full_frame {
// u1 frame_type = FULL_FRAME; /* 255 */
// u2 offset_delta;
// u2 number_of_locals;
// verification_type_info locals[number_of_locals];
// u2 number_of_stack_items;
// verification_type_info stack[number_of_stack_items];
// }
else if (frame_type == 255) {
assert(stackmap_p + 2 + 2 <= stackmap_end,
"no room for smallest full_frame");
stackmap_p += 2;
u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
stackmap_p += 2;
for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
calc_number_of_entries, frame_type, THREAD);
}
// Use the largest size for the number_of_stack_items, but only get
// the right number of bytes.
u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
stackmap_p += 2;
for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
calc_number_of_entries, frame_type, THREAD);
}
}
} // end while there is a stack_map_frame
assert(number_of_entries == calc_number_of_entries, "sanity check");
} // end rewrite_cp_refs_in_stack_map_table()
// Rewrite constant pool references in the verification type info
// portion of the method's stackmap table. These "structures" are
// adapted from the StackMapTable_attribute that is described in
// section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
//
// The verification_type_info structure is a u1 tag followed by 0 or
// more bytes of data:
//
// union verification_type_info {
// Top_variable_info;
// Integer_variable_info;
// Float_variable_info;
// Long_variable_info;
// Double_variable_info;
// Null_variable_info;
// UninitializedThis_variable_info;
// Object_variable_info;
// Uninitialized_variable_info;
// }
//
void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
address& stackmap_p_ref, address stackmap_end, u2 frame_i,
u1 frame_type, TRAPS) {
assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
u1 tag = *stackmap_p_ref;
stackmap_p_ref++;
switch (tag) {
// Top_variable_info {
// u1 tag = ITEM_Top; /* 0 */
// }
// verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
case 0: // fall through
// Integer_variable_info {
// u1 tag = ITEM_Integer; /* 1 */
// }
case ITEM_Integer: // fall through
// Float_variable_info {
// u1 tag = ITEM_Float; /* 2 */
// }
case ITEM_Float: // fall through
// Double_variable_info {
// u1 tag = ITEM_Double; /* 3 */
// }
case ITEM_Double: // fall through
// Long_variable_info {
// u1 tag = ITEM_Long; /* 4 */
// }
case ITEM_Long: // fall through
// Null_variable_info {
// u1 tag = ITEM_Null; /* 5 */
// }
case ITEM_Null: // fall through
// UninitializedThis_variable_info {
// u1 tag = ITEM_UninitializedThis; /* 6 */
// }
case ITEM_UninitializedThis:
// nothing more to do for the above tag types
break;
// Object_variable_info {
// u1 tag = ITEM_Object; /* 7 */
// u2 cpool_index;
// }
case ITEM_Object:
{
assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
u2 new_cp_index = find_new_index(cpool_index);
if (new_cp_index != 0) {
RC_TRACE_WITH_THREAD(0x04000000, THREAD,
("mapped old cpool_index=%d", cpool_index));
Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
cpool_index = new_cp_index;
}
stackmap_p_ref += 2;
RC_TRACE_WITH_THREAD(0x04000000, THREAD,
("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
frame_type, cpool_index));
} break;
// Uninitialized_variable_info {
// u1 tag = ITEM_Uninitialized; /* 8 */
// u2 offset;
// }
case ITEM_Uninitialized:
assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
stackmap_p_ref += 2;
break;
default:
RC_TRACE_WITH_THREAD(0x04000000, THREAD,
("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
ShouldNotReachHere();
break;
} // end switch (tag)
} // end rewrite_cp_refs_in_verification_type_info()
// Change the constant pool associated with klass scratch_class to
// scratch_cp. If shrink is true, then scratch_cp_length elements
// are copied from scratch_cp to a smaller constant pool and the
// smaller constant pool is associated with scratch_class.
void VM_RedefineClasses::set_new_constant_pool(
ClassLoaderData* loader_data,
instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
int scratch_cp_length, TRAPS) {
assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
// scratch_cp is a merged constant pool and has enough space for a
// worst case merge situation. We want to associate the minimum
// sized constant pool with the klass to save space.
ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
constantPoolHandle smaller_cp(THREAD, cp);
// preserve version() value in the smaller copy
int version = scratch_cp->version();
assert(version != 0, "sanity check");
smaller_cp->set_version(version);
// attach klass to new constant pool
// reference to the cp holder is needed for copy_operands()
smaller_cp->set_pool_holder(scratch_class());
scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
if (HAS_PENDING_EXCEPTION) {
// Exception is handled in the caller
loader_data->add_to_deallocate_list(smaller_cp());
return;
}
scratch_cp = smaller_cp;
// attach new constant pool to klass
scratch_class->set_constants(scratch_cp());
int i; // for portability
// update each field in klass to use new constant pool indices as needed
for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
jshort cur_index = fs.name_index();
jshort new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("field-name_index change: %d to %d", cur_index, new_index));
fs.set_name_index(new_index);
}
cur_index = fs.signature_index();
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("field-signature_index change: %d to %d", cur_index, new_index));
fs.set_signature_index(new_index);
}
cur_index = fs.initval_index();
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("field-initval_index change: %d to %d", cur_index, new_index));
fs.set_initval_index(new_index);
}
cur_index = fs.generic_signature_index();
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("field-generic_signature change: %d to %d", cur_index, new_index));
fs.set_generic_signature_index(new_index);
}
} // end for each field
// Update constant pool indices in the inner classes info to use
// new constant indices as needed. The inner classes info is a
// quadruple:
// (inner_class_info, outer_class_info, inner_name, inner_access_flags)
InnerClassesIterator iter(scratch_class);
for (; !iter.done(); iter.next()) {
int cur_index = iter.inner_class_info_index();
if (cur_index == 0) {
continue; // JVM spec. allows null inner class refs so skip it
}
int new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("inner_class_info change: %d to %d", cur_index, new_index));
iter.set_inner_class_info_index(new_index);
}
cur_index = iter.outer_class_info_index();
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("outer_class_info change: %d to %d", cur_index, new_index));
iter.set_outer_class_info_index(new_index);
}
cur_index = iter.inner_name_index();
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("inner_name change: %d to %d", cur_index, new_index));
iter.set_inner_name_index(new_index);
}
} // end for each inner class
// Attach each method in klass to the new constant pool and update
// to use new constant pool indices as needed:
Array<Method*>* methods = scratch_class->methods();
for (i = methods->length() - 1; i >= 0; i--) {
methodHandle method(THREAD, methods->at(i));
method->set_constants(scratch_cp());
int new_index = find_new_index(method->name_index());
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("method-name_index change: %d to %d", method->name_index(),
new_index));
method->set_name_index(new_index);
}
new_index = find_new_index(method->signature_index());
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("method-signature_index change: %d to %d",
method->signature_index(), new_index));
method->set_signature_index(new_index);
}
new_index = find_new_index(method->generic_signature_index());
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("method-generic_signature_index change: %d to %d",
method->generic_signature_index(), new_index));
method->set_generic_signature_index(new_index);
}
// Update constant pool indices in the method's checked exception
// table to use new constant indices as needed.
int cext_length = method->checked_exceptions_length();
if (cext_length > 0) {
CheckedExceptionElement * cext_table =
method->checked_exceptions_start();
for (int j = 0; j < cext_length; j++) {
int cur_index = cext_table[j].class_cp_index;
int new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("cext-class_cp_index change: %d to %d", cur_index, new_index));
cext_table[j].class_cp_index = (u2)new_index;
}
} // end for each checked exception table entry
} // end if there are checked exception table entries
// Update each catch type index in the method's exception table
// to use new constant pool indices as needed. The exception table
// holds quadruple entries of the form:
// (beg_bci, end_bci, handler_bci, klass_index)
ExceptionTable ex_table(method());
int ext_length = ex_table.length();
for (int j = 0; j < ext_length; j ++) {
int cur_index = ex_table.catch_type_index(j);
int new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("ext-klass_index change: %d to %d", cur_index, new_index));
ex_table.set_catch_type_index(j, new_index);
}
} // end for each exception table entry
// Update constant pool indices in the method's local variable
// table to use new constant indices as needed. The local variable
// table hold sextuple entries of the form:
// (start_pc, length, name_index, descriptor_index, signature_index, slot)
int lvt_length = method->localvariable_table_length();
if (lvt_length > 0) {
LocalVariableTableElement * lv_table =
method->localvariable_table_start();
for (int j = 0; j < lvt_length; j++) {
int cur_index = lv_table[j].name_cp_index;
int new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("lvt-name_cp_index change: %d to %d", cur_index, new_index));
lv_table[j].name_cp_index = (u2)new_index;
}
cur_index = lv_table[j].descriptor_cp_index;
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("lvt-descriptor_cp_index change: %d to %d", cur_index,
new_index));
lv_table[j].descriptor_cp_index = (u2)new_index;
}
cur_index = lv_table[j].signature_cp_index;
new_index = find_new_index(cur_index);
if (new_index != 0) {
RC_TRACE_WITH_THREAD(0x00080000, THREAD,
("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
lv_table[j].signature_cp_index = (u2)new_index;
}
} // end for each local variable table entry
} // end if there are local variable table entries
rewrite_cp_refs_in_stack_map_table(method, THREAD);
} // end for each method
} // end set_new_constant_pool()
// Unevolving classes may point to methods of the_class directly
// from their constant pool caches, itables, and/or vtables. We
// use the ClassLoaderDataGraph::classes_do() facility and this helper
// to fix up these pointers.
// Adjust cpools and vtables closure
void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
// This is a very busy routine. We don't want too much tracing
// printed out.
bool trace_name_printed = false;
// Very noisy: only enable this call if you are trying to determine
// that a specific class gets found by this routine.
// RC_TRACE macro has an embedded ResourceMark
// RC_TRACE_WITH_THREAD(0x00100000, THREAD,
// ("adjust check: name=%s", k->external_name()));
// trace_name_printed = true;
// If the class being redefined is java.lang.Object, we need to fix all
// array class vtables also
if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
k->vtable()->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
} else if (k->oop_is_instance()) {
HandleMark hm(_thread);
InstanceKlass *ik = InstanceKlass::cast(k);
// HotSpot specific optimization! HotSpot does not currently
// support delegation from the bootstrap class loader to a
// user-defined class loader. This means that if the bootstrap
// class loader is the initiating class loader, then it will also
// be the defining class loader. This also means that classes
// loaded by the bootstrap class loader cannot refer to classes
// loaded by a user-defined class loader. Note: a user-defined
// class loader can delegate to the bootstrap class loader.
//
// If the current class being redefined has a user-defined class
// loader as its defining class loader, then we can skip all
// classes loaded by the bootstrap class loader.
bool is_user_defined =
InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
if (is_user_defined && ik->class_loader() == NULL) {
return;
}
// Fix the vtable embedded in the_class and subclasses of the_class,
// if one exists. We discard scratch_class and we don't keep an
// InstanceKlass around to hold obsolete methods so we don't have
// any other InstanceKlass embedded vtables to update. The vtable
// holds the Method*s for virtual (but not final) methods.
// Default methods, or concrete methods in interfaces are stored
// in the vtable, so if an interface changes we need to check
// adjust_method_entries() for every InstanceKlass, which will also
// adjust the default method vtable indices.
// We also need to adjust any default method entries that are
// not yet in the vtable, because the vtable setup is in progress.
// This must be done after we adjust the default_methods and
// default_vtable_indices for methods already in the vtable.
if (ik->vtable_length() > 0 && (_the_class_oop->is_interface()
|| ik->is_subtype_of(_the_class_oop))) {
// ik->vtable() creates a wrapper object; rm cleans it up
ResourceMark rm(_thread);
ik->vtable()->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
ik->adjust_default_methods(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
}
// If the current class has an itable and we are either redefining an
// interface or if the current class is a subclass of the_class, then
// we potentially have to fix the itable. If we are redefining an
// interface, then we have to call adjust_method_entries() for
// every InstanceKlass that has an itable since there isn't a
// subclass relationship between an interface and an InstanceKlass.
if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
|| ik->is_subclass_of(_the_class_oop))) {
// ik->itable() creates a wrapper object; rm cleans it up
ResourceMark rm(_thread);
ik->itable()->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
}
// The constant pools in other classes (other_cp) can refer to
// methods in the_class. We have to update method information in
// other_cp's cache. If other_cp has a previous version, then we
// have to repeat the process for each previous version. The
// constant pool cache holds the Method*s for non-virtual
// methods and for virtual, final methods.
//
// Special case: if the current class is the_class, then new_cp
// has already been attached to the_class and old_cp has already
// been added as a previous version. The new_cp doesn't have any
// cached references to old methods so it doesn't need to be
// updated. We can simply start with the previous version(s) in
// that case.
constantPoolHandle other_cp;
ConstantPoolCache* cp_cache;
if (ik != _the_class_oop) {
// this klass' constant pool cache may need adjustment
other_cp = constantPoolHandle(ik->constants());
cp_cache = other_cp->cache();
if (cp_cache != NULL) {
cp_cache->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
}
}
// the previous versions' constant pool caches may need adjustment
PreviousVersionWalker pvw(_thread, ik);
for (PreviousVersionNode * pv_node = pvw.next_previous_version();
pv_node != NULL; pv_node = pvw.next_previous_version()) {
other_cp = pv_node->prev_constant_pool();
cp_cache = other_cp->cache();
if (cp_cache != NULL) {
cp_cache->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
}
}
}
}
void VM_RedefineClasses::update_jmethod_ids() {
for (int j = 0; j < _matching_methods_length; ++j) {
Method* old_method = _matching_old_methods[j];
jmethodID jmid = old_method->find_jmethod_id_or_null();
if (jmid != NULL) {
// There is a jmethodID, change it to point to the new method
methodHandle new_method_h(_matching_new_methods[j]);
Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
"should be replaced");
}
}
}
void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
BitMap *emcp_methods, int * emcp_method_count_p) {
*emcp_method_count_p = 0;
int obsolete_count = 0;
int old_index = 0;
for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
Method* old_method = _matching_old_methods[j];
Method* new_method = _matching_new_methods[j];
Method* old_array_method;
// Maintain an old_index into the _old_methods array by skipping
// deleted methods
while ((old_array_method = _old_methods->at(old_index)) != old_method) {
++old_index;
}
if (MethodComparator::methods_EMCP(old_method, new_method)) {
// The EMCP definition from JSR-163 requires the bytecodes to be
// the same with the exception of constant pool indices which may
// differ. However, the constants referred to by those indices
// must be the same.
//
// We use methods_EMCP() for comparison since constant pool
// merging can remove duplicate constant pool entries that were
// present in the old method and removed from the rewritten new
// method. A faster binary comparison function would consider the
// old and new methods to be different when they are actually
// EMCP.
//
// The old and new methods are EMCP and you would think that we
// could get rid of one of them here and now and save some space.
// However, the concept of EMCP only considers the bytecodes and
// the constant pool entries in the comparison. Other things,
// e.g., the line number table (LNT) or the local variable table
// (LVT) don't count in the comparison. So the new (and EMCP)
// method can have a new LNT that we need so we can't just
// overwrite the new method with the old method.
//
// When this routine is called, we have already attached the new
// methods to the_class so the old methods are effectively
// overwritten. However, if an old method is still executing,
// then the old method cannot be collected until sometime after
// the old method call has returned. So the overwriting of old
// methods by new methods will save us space except for those
// (hopefully few) old methods that are still executing.
//
// A method refers to a ConstMethod* and this presents another
// possible avenue to space savings. The ConstMethod* in the
// new method contains possibly new attributes (LNT, LVT, etc).
// At first glance, it seems possible to save space by replacing
// the ConstMethod* in the old method with the ConstMethod*
// from the new method. The old and new methods would share the
// same ConstMethod* and we would save the space occupied by
// the old ConstMethod*. However, the ConstMethod* contains
// a back reference to the containing method. Sharing the
// ConstMethod* between two methods could lead to confusion in
// the code that uses the back reference. This would lead to
// brittle code that could be broken in non-obvious ways now or
// in the future.
//
// Another possibility is to copy the ConstMethod* from the new
// method to the old method and then overwrite the new method with
// the old method. Since the ConstMethod* contains the bytecodes
// for the method embedded in the oop, this option would change
// the bytecodes out from under any threads executing the old
// method and make the thread's bcp invalid. Since EMCP requires
// that the bytecodes be the same modulo constant pool indices, it
// is straight forward to compute the correct new bcp in the new
// ConstMethod* from the old bcp in the old ConstMethod*. The
// time consuming part would be searching all the frames in all
// of the threads to find all of the calls to the old method.
//
// It looks like we will have to live with the limited savings
// that we get from effectively overwriting the old methods
// when the new methods are attached to the_class.
// track which methods are EMCP for add_previous_version() call
emcp_methods->set_bit(old_index);
(*emcp_method_count_p)++;
// An EMCP method is _not_ obsolete. An obsolete method has a
// different jmethodID than the current method. An EMCP method
// has the same jmethodID as the current method. Having the
// same jmethodID for all EMCP versions of a method allows for
// a consistent view of the EMCP methods regardless of which
// EMCP method you happen to have in hand. For example, a
// breakpoint set in one EMCP method will work for all EMCP
// versions of the method including the current one.
} else {
// mark obsolete methods as such
old_method->set_is_obsolete();
obsolete_count++;
// obsolete methods need a unique idnum so they become new entries in
// the jmethodID cache in InstanceKlass
u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
if (num != ConstMethod::UNSET_IDNUM) {
old_method->set_method_idnum(num);
}
// With tracing we try not to "yack" too much. The position of
// this trace assumes there are fewer obsolete methods than
// EMCP methods.
RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
old_method->name()->as_C_string(),
old_method->signature()->as_C_string()));
}
old_method->set_is_old();
}
for (int i = 0; i < _deleted_methods_length; ++i) {
Method* old_method = _deleted_methods[i];
assert(!old_method->has_vtable_index(),
"cannot delete methods with vtable entries");;
// Mark all deleted methods as old and obsolete
old_method->set_is_old();
old_method->set_is_obsolete();
++obsolete_count;
// With tracing we try not to "yack" too much. The position of
// this trace assumes there are fewer obsolete methods than
// EMCP methods.
RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
old_method->name()->as_C_string(),
old_method->signature()->as_C_string()));
}
assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
"sanity check");
RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
obsolete_count));
}
// This internal class transfers the native function registration from old methods
// to new methods. It is designed to handle both the simple case of unchanged
// native methods and the complex cases of native method prefixes being added and/or
// removed.
// It expects only to be used during the VM_RedefineClasses op (a safepoint).
//
// This class is used after the new methods have been installed in "the_class".
//
// So, for example, the following must be handled. Where 'm' is a method and
// a number followed by an underscore is a prefix.
//
// Old Name New Name
// Simple transfer to new method m -> m
// Add prefix m -> 1_m
// Remove prefix 1_m -> m
// Simultaneous add of prefixes m -> 3_2_1_m
// Simultaneous removal of prefixes 3_2_1_m -> m
// Simultaneous add and remove 1_m -> 2_m
// Same, caused by prefix removal only 3_2_1_m -> 3_2_m
//
class TransferNativeFunctionRegistration {
private:
instanceKlassHandle the_class;
int prefix_count;
char** prefixes;
// Recursively search the binary tree of possibly prefixed method names.
// Iteration could be used if all agents were well behaved. Full tree walk is
// more resilent to agents not cleaning up intermediate methods.
// Branch at each depth in the binary tree is:
// (1) without the prefix.
// (2) with the prefix.
// where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
Symbol* signature) {
TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
if (name_symbol != NULL) {
Method* method = the_class()->lookup_method(name_symbol, signature);
if (method != NULL) {
// Even if prefixed, intermediate methods must exist.
if (method->is_native()) {
// Wahoo, we found a (possibly prefixed) version of the method, return it.
return method;
}
if (depth < prefix_count) {
// Try applying further prefixes (other than this one).
method = search_prefix_name_space(depth+1, name_str, name_len, signature);
if (method != NULL) {
return method; // found
}
// Try adding this prefix to the method name and see if it matches
// another method name.
char* prefix = prefixes[depth];
size_t prefix_len = strlen(prefix);
size_t trial_len = name_len + prefix_len;
char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
strcpy(trial_name_str, prefix);
strcat(trial_name_str, name_str);
method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
signature);
if (method != NULL) {
// If found along this branch, it was prefixed, mark as such
method->set_is_prefixed_native();
return method; // found
}
}
}
}
return NULL; // This whole branch bore nothing
}
// Return the method name with old prefixes stripped away.
char* method_name_without_prefixes(Method* method) {
Symbol* name = method->name();
char* name_str = name->as_utf8();
// Old prefixing may be defunct, strip prefixes, if any.
for (int i = prefix_count-1; i >= 0; i--) {
char* prefix = prefixes[i];
size_t prefix_len = strlen(prefix);
if (strncmp(prefix, name_str, prefix_len) == 0) {
name_str += prefix_len;
}
}
return name_str;
}
// Strip any prefixes off the old native method, then try to find a
// (possibly prefixed) new native that matches it.
Method* strip_and_search_for_new_native(Method* method) {
ResourceMark rm;
char* name_str = method_name_without_prefixes(method);
return search_prefix_name_space(0, name_str, strlen(name_str),
method->signature());
}
public:
// Construct a native method transfer processor for this class.
TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
the_class = _the_class;
prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
}
// Attempt to transfer any of the old or deleted methods that are native
void transfer_registrations(Method** old_methods, int methods_length) {
for (int j = 0; j < methods_length; j++) {
Method* old_method = old_methods[j];
if (old_method->is_native() && old_method->has_native_function()) {
Method* new_method = strip_and_search_for_new_native(old_method);
if (new_method != NULL) {
// Actually set the native function in the new method.
// Redefine does not send events (except CFLH), certainly not this
// behind the scenes re-registration.
new_method->set_native_function(old_method->native_function(),
!Method::native_bind_event_is_interesting);
}
}
}
}
};
// Don't lose the association between a native method and its JNI function.
void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
TransferNativeFunctionRegistration transfer(the_class);
transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
}
// Deoptimize all compiled code that depends on this class.
//
// If the can_redefine_classes capability is obtained in the onload
// phase then the compiler has recorded all dependencies from startup.
// In that case we need only deoptimize and throw away all compiled code
// that depends on the class.
//
// If can_redefine_classes is obtained sometime after the onload
// phase then the dependency information may be incomplete. In that case
// the first call to RedefineClasses causes all compiled code to be
// thrown away. As can_redefine_classes has been obtained then
// all future compilations will record dependencies so second and
// subsequent calls to RedefineClasses need only throw away code
// that depends on the class.
//
void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
assert_locked_or_safepoint(Compile_lock);
// All dependencies have been recorded from startup or this is a second or
// subsequent use of RedefineClasses
if (JvmtiExport::all_dependencies_are_recorded()) {
Universe::flush_evol_dependents_on(k_h);
} else {
CodeCache::mark_all_nmethods_for_deoptimization();
ResourceMark rm(THREAD);
DeoptimizationMarker dm;
// Deoptimize all activations depending on marked nmethods
Deoptimization::deoptimize_dependents();
// Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
CodeCache::make_marked_nmethods_not_entrant();
// From now on we know that the dependency information is complete
JvmtiExport::set_all_dependencies_are_recorded(true);
}
}
void VM_RedefineClasses::compute_added_deleted_matching_methods() {
Method* old_method;
Method* new_method;
_matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
_matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
_added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
_deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
_matching_methods_length = 0;
_deleted_methods_length = 0;
_added_methods_length = 0;
int nj = 0;
int oj = 0;
while (true) {
if (oj >= _old_methods->length()) {
if (nj >= _new_methods->length()) {
break; // we've looked at everything, done
}
// New method at the end
new_method = _new_methods->at(nj);
_added_methods[_added_methods_length++] = new_method;
++nj;
} else if (nj >= _new_methods->length()) {
// Old method, at the end, is deleted
old_method = _old_methods->at(oj);
_deleted_methods[_deleted_methods_length++] = old_method;
++oj;
} else {
old_method = _old_methods->at(oj);
new_method = _new_methods->at(nj);
if (old_method->name() == new_method->name()) {
if (old_method->signature() == new_method->signature()) {
_matching_old_methods[_matching_methods_length ] = old_method;
_matching_new_methods[_matching_methods_length++] = new_method;
++nj;
++oj;
} else {
// added overloaded have already been moved to the end,
// so this is a deleted overloaded method
_deleted_methods[_deleted_methods_length++] = old_method;
++oj;
}
} else { // names don't match
if (old_method->name()->fast_compare(new_method->name()) > 0) {
// new method
_added_methods[_added_methods_length++] = new_method;
++nj;
} else {
// deleted method
_deleted_methods[_deleted_methods_length++] = old_method;
++oj;
}
}
}
}
assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
}
void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
instanceKlassHandle scratch_class) {
// Since there is currently no rewriting of type annotations indexes
// into the CP, we null out type annotations on scratch_class before
// we swap annotations with the_class rather than facing the
// possibility of shipping annotations with broken indexes to
// Java-land.
ClassLoaderData* loader_data = scratch_class->class_loader_data();
AnnotationArray* new_class_type_annotations = scratch_class->class_type_annotations();
if (new_class_type_annotations != NULL) {
MetadataFactory::free_array<u1>(loader_data, new_class_type_annotations);
scratch_class->annotations()->set_class_type_annotations(NULL);
}
Array<AnnotationArray*>* new_field_type_annotations = scratch_class->fields_type_annotations();
if (new_field_type_annotations != NULL) {
Annotations::free_contents(loader_data, new_field_type_annotations);
scratch_class->annotations()->set_fields_type_annotations(NULL);
}
// Swap annotation fields values
Annotations* old_annotations = the_class->annotations();
the_class->set_annotations(scratch_class->annotations());
scratch_class->set_annotations(old_annotations);
}
// Install the redefinition of a class:
// - house keeping (flushing breakpoints and caches, deoptimizing
// dependent compiled code)
// - replacing parts in the_class with parts from scratch_class
// - adding a weak reference to track the obsolete but interesting
// parts of the_class
// - adjusting constant pool caches and vtables in other classes
// that refer to methods in the_class. These adjustments use the
// ClassLoaderDataGraph::classes_do() facility which only allows
// a helper method to be specified. The interesting parameters
// that we would like to pass to the helper method are saved in
// static global fields in the VM operation.
void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
Klass* scratch_class_oop, TRAPS) {
HandleMark hm(THREAD); // make sure handles from this call are freed
RC_TIMER_START(_timer_rsc_phase1);
instanceKlassHandle scratch_class(scratch_class_oop);
oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
// Remove all breakpoints in methods of this class
JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
// Deoptimize all compiled code that depends on this class
flush_dependent_code(the_class, THREAD);
_old_methods = the_class->methods();
_new_methods = scratch_class->methods();
_the_class_oop = the_class_oop;
compute_added_deleted_matching_methods();
update_jmethod_ids();
// Attach new constant pool to the original klass. The original
// klass still refers to the old constant pool (for now).
scratch_class->constants()->set_pool_holder(the_class());
#if 0
// In theory, with constant pool merging in place we should be able
// to save space by using the new, merged constant pool in place of
// the old constant pool(s). By "pool(s)" I mean the constant pool in
// the klass version we are replacing now and any constant pool(s) in
// previous versions of klass. Nice theory, doesn't work in practice.
// When this code is enabled, even simple programs throw NullPointer
// exceptions. I'm guessing that this is caused by some constant pool
// cache difference between the new, merged constant pool and the
// constant pool that was just being used by the klass. I'm keeping
// this code around to archive the idea, but the code has to remain
// disabled for now.
// Attach each old method to the new constant pool. This can be
// done here since we are past the bytecode verification and
// constant pool optimization phases.
for (int i = _old_methods->length() - 1; i >= 0; i--) {
Method* method = _old_methods->at(i);
method->set_constants(scratch_class->constants());
}
{
// walk all previous versions of the klass
InstanceKlass *ik = (InstanceKlass *)the_class();
PreviousVersionWalker pvw(ik);
instanceKlassHandle ikh;
do {
ikh = pvw.next_previous_version();
if (!ikh.is_null()) {
ik = ikh();
// attach previous version of klass to the new constant pool
ik->set_constants(scratch_class->constants());
// Attach each method in the previous version of klass to the
// new constant pool
Array<Method*>* prev_methods = ik->methods();
for (int i = prev_methods->length() - 1; i >= 0; i--) {
Method* method = prev_methods->at(i);
method->set_constants(scratch_class->constants());
}
}
} while (!ikh.is_null());
}
#endif
// Replace methods and constantpool
the_class->set_methods(_new_methods);
scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
// and to be able to undo operation easily.
ConstantPool* old_constants = the_class->constants();
the_class->set_constants(scratch_class->constants());
scratch_class->set_constants(old_constants); // See the previous comment.
#if 0
// We are swapping the guts of "the new class" with the guts of "the
// class". Since the old constant pool has just been attached to "the
// new class", it seems logical to set the pool holder in the old
// constant pool also. However, doing this will change the observable
// class hierarchy for any old methods that are still executing. A
// method can query the identity of its "holder" and this query uses
// the method's constant pool link to find the holder. The change in
// holding class from "the class" to "the new class" can confuse
// things.
//
// Setting the old constant pool's holder will also cause
// verification done during vtable initialization below to fail.
// During vtable initialization, the vtable's class is verified to be
// a subtype of the method's holder. The vtable's class is "the
// class" and the method's holder is gotten from the constant pool
// link in the method itself. For "the class"'s directly implemented
// methods, the method holder is "the class" itself (as gotten from
// the new constant pool). The check works fine in this case. The
// check also works fine for methods inherited from super classes.
//
// Miranda methods are a little more complicated. A miranda method is
// provided by an interface when the class implementing the interface
// does not provide its own method. These interfaces are implemented
// internally as an InstanceKlass. These special instanceKlasses
// share the constant pool of the class that "implements" the
// interface. By sharing the constant pool, the method holder of a
// miranda method is the class that "implements" the interface. In a
// non-redefine situation, the subtype check works fine. However, if
// the old constant pool's pool holder is modified, then the check
// fails because there is no class hierarchy relationship between the
// vtable's class and "the new class".
old_constants->set_pool_holder(scratch_class());
#endif
// track which methods are EMCP for add_previous_version() call below
BitMap emcp_methods(_old_methods->length());
int emcp_method_count = 0;
emcp_methods.clear(); // clears 0..(length() - 1)
check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
transfer_old_native_function_registrations(the_class);
// The class file bytes from before any retransformable agents mucked
// with them was cached on the scratch class, move to the_class.
// Note: we still want to do this if nothing needed caching since it
// should get cleared in the_class too.
if (the_class->get_cached_class_file_bytes() == 0) {
// the_class doesn't have a cache yet so copy it
the_class->set_cached_class_file(scratch_class->get_cached_class_file());
}
#ifndef PRODUCT
else {
assert(the_class->get_cached_class_file_bytes() ==
scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
assert(the_class->get_cached_class_file_len() ==
scratch_class->get_cached_class_file_len(), "cache lens must match");
}
#endif
// NULL out in scratch class to not delete twice. The class to be redefined
// always owns these bytes.
scratch_class->set_cached_class_file(NULL);
// Replace inner_classes
Array<u2>* old_inner_classes = the_class->inner_classes();
the_class->set_inner_classes(scratch_class->inner_classes());
scratch_class->set_inner_classes(old_inner_classes);
// Initialize the vtable and interface table after
// methods have been rewritten
{
ResourceMark rm(THREAD);
// no exception should happen here since we explicitly
// do not check loader constraints.
// compare_and_normalize_class_versions has already checked:
// - classloaders unchanged, signatures unchanged
// - all instanceKlasses for redefined classes reused & contents updated
the_class->vtable()->initialize_vtable(false, THREAD);
the_class->itable()->initialize_itable(false, THREAD);
assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
}
// Leave arrays of jmethodIDs and itable index cache unchanged
// Copy the "source file name" attribute from new class version
the_class->set_source_file_name_index(
scratch_class->source_file_name_index());
// Copy the "source debug extension" attribute from new class version
the_class->set_source_debug_extension(
scratch_class->source_debug_extension(),
scratch_class->source_debug_extension() == NULL ? 0 :
(int)strlen(scratch_class->source_debug_extension()));
// Use of javac -g could be different in the old and the new
if (scratch_class->access_flags().has_localvariable_table() !=
the_class->access_flags().has_localvariable_table()) {
AccessFlags flags = the_class->access_flags();
if (scratch_class->access_flags().has_localvariable_table()) {
flags.set_has_localvariable_table();
} else {
flags.clear_has_localvariable_table();
}
the_class->set_access_flags(flags);
}
swap_annotations(the_class, scratch_class);
// Replace minor version number of class file
u2 old_minor_version = the_class->minor_version();
the_class->set_minor_version(scratch_class->minor_version());
scratch_class->set_minor_version(old_minor_version);
// Replace major version number of class file
u2 old_major_version = the_class->major_version();
the_class->set_major_version(scratch_class->major_version());
scratch_class->set_major_version(old_major_version);
// Replace CP indexes for class and name+type of enclosing method
u2 old_class_idx = the_class->enclosing_method_class_index();
u2 old_method_idx = the_class->enclosing_method_method_index();
the_class->set_enclosing_method_indices(
scratch_class->enclosing_method_class_index(),
scratch_class->enclosing_method_method_index());
scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
// keep track of previous versions of this class
the_class->add_previous_version(scratch_class, &emcp_methods,
emcp_method_count);
RC_TIMER_STOP(_timer_rsc_phase1);
RC_TIMER_START(_timer_rsc_phase2);
// Adjust constantpool caches and vtables for all classes
// that reference methods of the evolved class.
AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
// JSR-292 support
MemberNameTable* mnt = the_class->member_names();
if (mnt != NULL) {
bool trace_name_printed = false;
mnt->adjust_method_entries(_matching_old_methods,
_matching_new_methods,
_matching_methods_length,
&trace_name_printed);
}
// Fix Resolution Error table also to remove old constant pools
SystemDictionary::delete_resolution_error(old_constants);
if (the_class->oop_map_cache() != NULL) {
// Flush references to any obsolete methods from the oop map cache
// so that obsolete methods are not pinned.
the_class->oop_map_cache()->flush_obsolete_entries();
}
// increment the classRedefinedCount field in the_class and in any
// direct and indirect subclasses of the_class
increment_class_counter((InstanceKlass *)the_class(), THREAD);
// RC_TRACE macro has an embedded ResourceMark
RC_TRACE_WITH_THREAD(0x00000001, THREAD,
("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
the_class->external_name(),
java_lang_Class::classRedefinedCount(the_class_mirror),
os::available_memory() >> 10));
RC_TIMER_STOP(_timer_rsc_phase2);
} // end redefine_single_class()
// Increment the classRedefinedCount field in the specific InstanceKlass
// and in all direct and indirect subclasses.
void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
oop class_mirror = ik->java_mirror();
Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
if (class_oop != _the_class_oop) {
// _the_class_oop count is printed at end of redefine_single_class()
RC_TRACE_WITH_THREAD(0x00000008, THREAD,
("updated count in subclass=%s to %d", ik->external_name(), new_count));
}
for (Klass *subk = ik->subklass(); subk != NULL;
subk = subk->next_sibling()) {
if (subk->oop_is_instance()) {
// Only update instanceKlasses
InstanceKlass *subik = (InstanceKlass*)subk;
// recursively do subclasses of the current subclass
increment_class_counter(subik, THREAD);
}
}
}
void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
bool no_old_methods = true; // be optimistic
// Both array and instance classes have vtables.
// a vtable should never contain old or obsolete methods
ResourceMark rm(_thread);
if (k->vtable_length() > 0 &&
!k->vtable()->check_no_old_or_obsolete_entries()) {
if (RC_TRACE_ENABLED(0x00004000)) {
RC_TRACE_WITH_THREAD(0x00004000, _thread,
("klassVtable::check_no_old_or_obsolete_entries failure"
" -- OLD or OBSOLETE method found -- class: %s",
k->signature_name()));
k->vtable()->dump_vtable();
}
no_old_methods = false;
}
if (k->oop_is_instance()) {
HandleMark hm(_thread);
InstanceKlass *ik = InstanceKlass::cast(k);
// an itable should never contain old or obsolete methods
if (ik->itable_length() > 0 &&
!ik->itable()->check_no_old_or_obsolete_entries()) {
if (RC_TRACE_ENABLED(0x00004000)) {
RC_TRACE_WITH_THREAD(0x00004000, _thread,
("klassItable::check_no_old_or_obsolete_entries failure"
" -- OLD or OBSOLETE method found -- class: %s",
ik->signature_name()));
ik->itable()->dump_itable();
}
no_old_methods = false;
}
// the constant pool cache should never contain old or obsolete methods
if (ik->constants() != NULL &&
ik->constants()->cache() != NULL &&
!ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
if (RC_TRACE_ENABLED(0x00004000)) {
RC_TRACE_WITH_THREAD(0x00004000, _thread,
("cp-cache::check_no_old_or_obsolete_entries failure"
" -- OLD or OBSOLETE method found -- class: %s",
ik->signature_name()));
ik->constants()->cache()->dump_cache();
}
no_old_methods = false;
}
}
// print and fail guarantee if old methods are found.
if (!no_old_methods) {
if (RC_TRACE_ENABLED(0x00004000)) {
dump_methods();
} else {
tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
"to see more info about the following guarantee() failure.");
}
guarantee(false, "OLD and/or OBSOLETE method(s) found");
}
}
void VM_RedefineClasses::dump_methods() {
int j;
RC_TRACE(0x00004000, ("_old_methods --"));
for (j = 0; j < _old_methods->length(); ++j) {
Method* m = _old_methods->at(j);
RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
m->access_flags().print_on(tty);
tty->print(" -- ");
m->print_name(tty);
tty->cr();
}
RC_TRACE(0x00004000, ("_new_methods --"));
for (j = 0; j < _new_methods->length(); ++j) {
Method* m = _new_methods->at(j);
RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
m->access_flags().print_on(tty);
tty->print(" -- ");
m->print_name(tty);
tty->cr();
}
RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
for (j = 0; j < _matching_methods_length; ++j) {
Method* m = _matching_old_methods[j];
RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
m->access_flags().print_on(tty);
tty->print(" -- ");
m->print_name(tty);
tty->cr();
m = _matching_new_methods[j];
RC_TRACE_NO_CR(0x00004000, (" (%5d) ", m->vtable_index()));
m->access_flags().print_on(tty);
tty->cr();
}
RC_TRACE(0x00004000, ("_deleted_methods --"));
for (j = 0; j < _deleted_methods_length; ++j) {
Method* m = _deleted_methods[j];
RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
m->access_flags().print_on(tty);
tty->print(" -- ");
m->print_name(tty);
tty->cr();
}
RC_TRACE(0x00004000, ("_added_methods --"));
for (j = 0; j < _added_methods_length; ++j) {
Method* m = _added_methods[j];
RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
m->access_flags().print_on(tty);
tty->print(" -- ");
m->print_name(tty);
tty->cr();
}
}
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