hotspot/src/share/vm/prims/jvmtiClassFileReconstituter.cpp
changeset 1 489c9b5090e2
child 2570 ecc7862946d4
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/prims/jvmtiClassFileReconstituter.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,677 @@
+/*
+ * Copyright 2005-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+# include "incls/_precompiled.incl"
+# include "incls/_jvmtiClassFileReconstituter.cpp.incl"
+
+// FIXME: add Deprecated, LVT, LVTT attributes
+// FIXME: fix Synthetic attribute
+// FIXME: per Serguei, add error return handling for constantPoolOopDesc::copy_cpool_bytes()
+
+
+// Write the field information portion of ClassFile structure
+// JVMSpec|     u2 fields_count;
+// JVMSpec|     field_info fields[fields_count];
+void JvmtiClassFileReconstituter::write_field_infos() {
+  HandleMark hm(thread());
+  typeArrayHandle fields(thread(), ikh()->fields());
+  int fields_length = fields->length();
+  int num_fields = fields_length / instanceKlass::next_offset;
+  objArrayHandle fields_anno(thread(), ikh()->fields_annotations());
+
+  write_u2(num_fields);
+  for (int index = 0; index < fields_length; index += instanceKlass::next_offset) {
+    AccessFlags access_flags;
+    int flags = fields->ushort_at(index + instanceKlass::access_flags_offset);
+    access_flags.set_flags(flags);
+    int name_index = fields->ushort_at(index + instanceKlass::name_index_offset);
+    int signature_index = fields->ushort_at(index + instanceKlass::signature_index_offset);
+    int initial_value_index = fields->ushort_at(index + instanceKlass::initval_index_offset);
+    guarantee(name_index != 0 && signature_index != 0, "bad constant pool index for field");
+    int offset = ikh()->offset_from_fields( index );
+    int generic_signature_index =
+                        fields->ushort_at(index + instanceKlass::generic_signature_offset);
+    typeArrayHandle anno(thread(), fields_anno.not_null() ?
+                                 (typeArrayOop)(fields_anno->obj_at(index / instanceKlass::next_offset)) :
+                                 (typeArrayOop)NULL);
+
+    // JVMSpec|   field_info {
+    // JVMSpec|         u2 access_flags;
+    // JVMSpec|         u2 name_index;
+    // JVMSpec|         u2 descriptor_index;
+    // JVMSpec|         u2 attributes_count;
+    // JVMSpec|         attribute_info attributes[attributes_count];
+    // JVMSpec|   }
+
+    write_u2(flags & JVM_RECOGNIZED_FIELD_MODIFIERS);
+    write_u2(name_index);
+    write_u2(signature_index);
+    int attr_count = 0;
+    if (initial_value_index != 0) {
+      ++attr_count;
+    }
+    if (access_flags.is_synthetic()) {
+      // ++attr_count;
+    }
+    if (generic_signature_index != 0) {
+      ++attr_count;
+    }
+    if (anno.not_null()) {
+      ++attr_count;     // has RuntimeVisibleAnnotations attribute
+    }
+
+    write_u2(attr_count);
+
+    if (initial_value_index != 0) {
+      write_attribute_name_index("ConstantValue");
+      write_u4(2); //length always 2
+      write_u2(initial_value_index);
+    }
+    if (access_flags.is_synthetic()) {
+      // write_synthetic_attribute();
+    }
+    if (generic_signature_index != 0) {
+      write_signature_attribute(generic_signature_index);
+    }
+    if (anno.not_null()) {
+      write_annotations_attribute("RuntimeVisibleAnnotations", anno);
+    }
+  }
+}
+
+// Write Code attribute
+// JVMSpec|   Code_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 max_stack;
+// JVMSpec|     u2 max_locals;
+// JVMSpec|     u4 code_length;
+// JVMSpec|     u1 code[code_length];
+// JVMSpec|     u2 exception_table_length;
+// JVMSpec|     {       u2 start_pc;
+// JVMSpec|             u2 end_pc;
+// JVMSpec|             u2  handler_pc;
+// JVMSpec|             u2  catch_type;
+// JVMSpec|     }       exception_table[exception_table_length];
+// JVMSpec|     u2 attributes_count;
+// JVMSpec|     attribute_info attributes[attributes_count];
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_code_attribute(methodHandle method) {
+  constMethodHandle const_method(thread(), method->constMethod());
+  u2 line_num_cnt = 0;
+  int stackmap_len = 0;
+
+  // compute number and length of attributes -- FIXME: for now no LVT
+  int attr_count = 0;
+  int attr_size = 0;
+  if (const_method->has_linenumber_table()) {
+    line_num_cnt = line_number_table_entries(method);
+    if (line_num_cnt != 0) {
+      ++attr_count;
+      // Compute the complete size of the line number table attribute:
+      //      LineNumberTable_attribute {
+      //        u2 attribute_name_index;
+      //        u4 attribute_length;
+      //        u2 line_number_table_length;
+      //        {  u2 start_pc;
+      //           u2 line_number;
+      //        } line_number_table[line_number_table_length];
+      //      }
+      attr_size += 2 + 4 + 2 + line_num_cnt * (2 + 2);
+    }
+  }
+  if (method->has_stackmap_table()) {
+    stackmap_len = method->stackmap_data()->length();
+    if (stackmap_len != 0) {
+      ++attr_count;
+      // Compute the  size of the stack map table attribute (VM stores raw):
+      //      StackMapTable_attribute {
+      //        u2 attribute_name_index;
+      //        u4 attribute_length;
+      //        u2 number_of_entries;
+      //        stack_map_frame_entries[number_of_entries];
+      //      }
+      attr_size += 2 + 4 + stackmap_len;
+    }
+  }
+
+  typeArrayHandle exception_table(thread(), const_method->exception_table());
+  int exception_table_length = exception_table->length();
+  int exception_table_entries = exception_table_length / 4;
+  int code_size = const_method->code_size();
+  int size =
+    2+2+4 +                                // max_stack, max_locals, code_length
+    code_size +                            // code
+    2 +                                    // exception_table_length
+    (2+2+2+2) * exception_table_entries +  // exception_table
+    2 +                                    // attributes_count
+    attr_size;                             // attributes
+
+  write_attribute_name_index("Code");
+  write_u4(size);
+  write_u2(method->max_stack());
+  write_u2(method->max_locals());
+  write_u4(code_size);
+  copy_bytecodes(method, (unsigned char*)writeable_address(code_size));
+  write_u2(exception_table_entries);
+  for (int index = 0; index < exception_table_length; ) {
+    write_u2(exception_table->int_at(index++));
+    write_u2(exception_table->int_at(index++));
+    write_u2(exception_table->int_at(index++));
+    write_u2(exception_table->int_at(index++));
+  }
+  write_u2(attr_count);
+  if (line_num_cnt != 0) {
+    write_line_number_table_attribute(method, line_num_cnt);
+  }
+  if (stackmap_len != 0) {
+    write_stackmap_table_attribute(method, stackmap_len);
+  }
+
+  // FIXME: write LVT attribute
+}
+
+// Write Exceptions attribute
+// JVMSpec|   Exceptions_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 number_of_exceptions;
+// JVMSpec|     u2 exception_index_table[number_of_exceptions];
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_exceptions_attribute(constMethodHandle const_method) {
+  CheckedExceptionElement* checked_exceptions = const_method->checked_exceptions_start();
+  int checked_exceptions_length = const_method->checked_exceptions_length();
+  int size =
+    2 +                                    // number_of_exceptions
+    2 * checked_exceptions_length;         // exception_index_table
+
+  write_attribute_name_index("Exceptions");
+  write_u4(size);
+  write_u2(checked_exceptions_length);
+  for (int index = 0; index < checked_exceptions_length; index++) {
+    write_u2(checked_exceptions[index].class_cp_index);
+  }
+}
+
+// Write SourceFile attribute
+// JVMSpec|   SourceFile_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 sourcefile_index;
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_source_file_attribute() {
+  assert(ikh()->source_file_name() != NULL, "caller must check");
+
+  write_attribute_name_index("SourceFile");
+  write_u4(2);  // always length 2
+  write_u2(symbol_to_cpool_index(ikh()->source_file_name()));
+}
+
+// Write SourceDebugExtension attribute
+// JSR45|   SourceDebugExtension_attribute {
+// JSR45|       u2 attribute_name_index;
+// JSR45|       u4 attribute_length;
+// JSR45|       u2 sourcefile_index;
+// JSR45|   }
+void JvmtiClassFileReconstituter::write_source_debug_extension_attribute() {
+  assert(ikh()->source_debug_extension() != NULL, "caller must check");
+
+  write_attribute_name_index("SourceDebugExtension");
+  write_u4(2);  // always length 2
+  write_u2(symbol_to_cpool_index(ikh()->source_debug_extension()));
+}
+
+// Write (generic) Signature attribute
+// JVMSpec|   Signature_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 signature_index;
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_signature_attribute(u2 generic_signature_index) {
+  write_attribute_name_index("Signature");
+  write_u4(2);  // always length 2
+  write_u2(generic_signature_index);
+}
+
+// Compute the number of entries in the InnerClasses attribute
+u2 JvmtiClassFileReconstituter::inner_classes_attribute_length() {
+  typeArrayOop inner_class_list = ikh()->inner_classes();
+  return (inner_class_list == NULL) ? 0 : inner_class_list->length();
+}
+
+// Write an annotation attribute.  The VM stores them in raw form, so all we need
+// to do is add the attrubute name and fill in the length.
+// JSR202|   *Annotations_attribute {
+// JSR202|     u2 attribute_name_index;
+// JSR202|     u4 attribute_length;
+// JSR202|     ...
+// JSR202|   }
+void JvmtiClassFileReconstituter::write_annotations_attribute(const char* attr_name,
+                                                              typeArrayHandle annos) {
+  u4 length = annos->length();
+  write_attribute_name_index(attr_name);
+  write_u4(length);
+  memcpy(writeable_address(length), annos->byte_at_addr(0), length);
+}
+
+
+// Write InnerClasses attribute
+// JVMSpec|   InnerClasses_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 number_of_classes;
+// JVMSpec|     {  u2 inner_class_info_index;
+// JVMSpec|        u2 outer_class_info_index;
+// JVMSpec|        u2 inner_name_index;
+// JVMSpec|        u2 inner_class_access_flags;
+// JVMSpec|     } classes[number_of_classes];
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_inner_classes_attribute(int length) {
+  typeArrayOop inner_class_list = ikh()->inner_classes();
+  guarantee(inner_class_list != NULL && inner_class_list->length() == length,
+            "caller must check");
+  typeArrayHandle inner_class_list_h(thread(), inner_class_list);
+  assert (length % instanceKlass::inner_class_next_offset == 0, "just checking");
+  u2 entry_count = length / instanceKlass::inner_class_next_offset;
+  u4 size = 2 + entry_count * (2+2+2+2);
+
+  write_attribute_name_index("InnerClasses");
+  write_u4(size);
+  write_u2(entry_count);
+  for (int i = 0; i < length; i += instanceKlass::inner_class_next_offset) {
+    write_u2(inner_class_list_h->ushort_at(
+                      i + instanceKlass::inner_class_inner_class_info_offset));
+    write_u2(inner_class_list_h->ushort_at(
+                      i + instanceKlass::inner_class_outer_class_info_offset));
+    write_u2(inner_class_list_h->ushort_at(
+                      i + instanceKlass::inner_class_inner_name_offset));
+    write_u2(inner_class_list_h->ushort_at(
+                      i + instanceKlass::inner_class_access_flags_offset));
+  }
+}
+
+// Write Synthetic attribute
+// JVMSpec|   Synthetic_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_synthetic_attribute() {
+  write_attribute_name_index("Synthetic");
+  write_u4(0); //length always zero
+}
+
+// Compute size of LineNumberTable
+u2 JvmtiClassFileReconstituter::line_number_table_entries(methodHandle method) {
+  // The line number table is compressed so we don't know how big it is until decompressed.
+  // Decompression is really fast so we just do it twice.
+  u2 num_entries = 0;
+  CompressedLineNumberReadStream stream(method->compressed_linenumber_table());
+  while (stream.read_pair()) {
+    num_entries++;
+  }
+  return num_entries;
+}
+
+// Write LineNumberTable attribute
+// JVMSpec|   LineNumberTable_attribute {
+// JVMSpec|     u2 attribute_name_index;
+// JVMSpec|     u4 attribute_length;
+// JVMSpec|     u2 line_number_table_length;
+// JVMSpec|     {  u2 start_pc;
+// JVMSpec|        u2 line_number;
+// JVMSpec|     } line_number_table[line_number_table_length];
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_line_number_table_attribute(methodHandle method,
+                                                                    u2 num_entries) {
+
+  write_attribute_name_index("LineNumberTable");
+  write_u4(2 + num_entries * (2 + 2));
+  write_u2(num_entries);
+
+  CompressedLineNumberReadStream stream(method->compressed_linenumber_table());
+  while (stream.read_pair()) {
+    write_u2(stream.bci());
+    write_u2(stream.line());
+  }
+}
+
+// Write stack map table attribute
+// JSR-202|   StackMapTable_attribute {
+// JSR-202|     u2 attribute_name_index;
+// JSR-202|     u4 attribute_length;
+// JSR-202|     u2 number_of_entries;
+// JSR-202|     stack_map_frame_entries[number_of_entries];
+// JSR-202|   }
+void JvmtiClassFileReconstituter::write_stackmap_table_attribute(methodHandle method,
+                                                                 int stackmap_len) {
+
+  write_attribute_name_index("StackMapTable");
+  write_u4(stackmap_len);
+  memcpy(
+    writeable_address(stackmap_len),
+    (void*)(method->stackmap_data()->byte_at_addr(0)),
+    stackmap_len);
+}
+
+// Write one method_info structure
+// JVMSpec|   method_info {
+// JVMSpec|     u2 access_flags;
+// JVMSpec|     u2 name_index;
+// JVMSpec|     u2 descriptor_index;
+// JVMSpec|     u2 attributes_count;
+// JVMSpec|     attribute_info attributes[attributes_count];
+// JVMSpec|   }
+void JvmtiClassFileReconstituter::write_method_info(methodHandle method) {
+  AccessFlags access_flags = method->access_flags();
+  constMethodHandle const_method(thread(), method->constMethod());
+  u2 generic_signature_index = const_method->generic_signature_index();
+  typeArrayHandle anno(thread(), method->annotations());
+  typeArrayHandle param_anno(thread(), method->parameter_annotations());
+  typeArrayHandle default_anno(thread(), method->annotation_default());
+
+  write_u2(access_flags.get_flags() & JVM_RECOGNIZED_METHOD_MODIFIERS);
+  write_u2(const_method->name_index());
+  write_u2(const_method->signature_index());
+
+  // write attributes in the same order javac does, so we can test with byte for
+  // byte comparison
+  int attr_count = 0;
+  if (const_method->code_size() != 0) {
+    ++attr_count;     // has Code attribute
+  }
+  if (const_method->has_checked_exceptions()) {
+    ++attr_count;     // has Exceptions attribute
+  }
+  if (default_anno.not_null()) {
+    ++attr_count;     // has AnnotationDefault attribute
+  }
+  // Deprecated attribute would go here
+  if (access_flags.is_synthetic()) { // FIXME
+    // ++attr_count;
+  }
+  if (generic_signature_index != 0) {
+    ++attr_count;
+  }
+  if (anno.not_null()) {
+    ++attr_count;     // has RuntimeVisibleAnnotations attribute
+  }
+  if (param_anno.not_null()) {
+    ++attr_count;     // has RuntimeVisibleParameterAnnotations attribute
+  }
+
+  write_u2(attr_count);
+  if (const_method->code_size() > 0) {
+    write_code_attribute(method);
+  }
+  if (const_method->has_checked_exceptions()) {
+    write_exceptions_attribute(const_method);
+  }
+  if (default_anno.not_null()) {
+    write_annotations_attribute("AnnotationDefault", default_anno);
+  }
+  // Deprecated attribute would go here
+  if (access_flags.is_synthetic()) {
+    // write_synthetic_attribute();
+  }
+  if (generic_signature_index != 0) {
+    write_signature_attribute(generic_signature_index);
+  }
+  if (anno.not_null()) {
+    write_annotations_attribute("RuntimeVisibleAnnotations", anno);
+  }
+  if (param_anno.not_null()) {
+    write_annotations_attribute("RuntimeVisibleParameterAnnotations", param_anno);
+  }
+}
+
+// Write the class attributes portion of ClassFile structure
+// JVMSpec|     u2 attributes_count;
+// JVMSpec|     attribute_info attributes[attributes_count];
+void JvmtiClassFileReconstituter::write_class_attributes() {
+  u2 inner_classes_length = inner_classes_attribute_length();
+  symbolHandle generic_signature(thread(), ikh()->generic_signature());
+  typeArrayHandle anno(thread(), ikh()->class_annotations());
+
+  int attr_count = 0;
+  if (generic_signature() != NULL) {
+    ++attr_count;
+  }
+  if (ikh()->source_file_name() != NULL) {
+    ++attr_count;
+  }
+  if (ikh()->source_debug_extension() != NULL) {
+    ++attr_count;
+  }
+  if (inner_classes_length > 0) {
+    ++attr_count;
+  }
+  if (anno.not_null()) {
+    ++attr_count;     // has RuntimeVisibleAnnotations attribute
+  }
+
+  write_u2(attr_count);
+
+  if (generic_signature() != NULL) {
+    write_signature_attribute(symbol_to_cpool_index(generic_signature()));
+  }
+  if (ikh()->source_file_name() != NULL) {
+    write_source_file_attribute();
+  }
+  if (ikh()->source_debug_extension() != NULL) {
+    write_source_debug_extension_attribute();
+  }
+  if (inner_classes_length > 0) {
+    write_inner_classes_attribute(inner_classes_length);
+  }
+  if (anno.not_null()) {
+    write_annotations_attribute("RuntimeVisibleAnnotations", anno);
+  }
+}
+
+// Write the method information portion of ClassFile structure
+// JVMSpec|     u2 methods_count;
+// JVMSpec|     method_info methods[methods_count];
+void JvmtiClassFileReconstituter::write_method_infos() {
+  HandleMark hm(thread());
+  objArrayHandle methods(thread(), ikh()->methods());
+  int num_methods = methods->length();
+
+  write_u2(num_methods);
+  if (JvmtiExport::can_maintain_original_method_order()) {
+    int index;
+    int original_index;
+    int* method_order = NEW_RESOURCE_ARRAY(int, num_methods);
+
+    // invert the method order mapping
+    for (index = 0; index < num_methods; index++) {
+      original_index = ikh()->method_ordering()->int_at(index);
+      assert(original_index >= 0 && original_index < num_methods,
+             "invalid original method index");
+      method_order[original_index] = index;
+    }
+
+    // write in original order
+    for (original_index = 0; original_index < num_methods; original_index++) {
+      index = method_order[original_index];
+      methodHandle method(thread(), (methodOop)(ikh()->methods()->obj_at(index)));
+      write_method_info(method);
+    }
+  } else {
+    // method order not preserved just dump the method infos
+    for (int index = 0; index < num_methods; index++) {
+      methodHandle method(thread(), (methodOop)(ikh()->methods()->obj_at(index)));
+      write_method_info(method);
+    }
+  }
+}
+
+void JvmtiClassFileReconstituter::write_class_file_format() {
+  ReallocMark();
+
+  // JVMSpec|   ClassFile {
+  // JVMSpec|           u4 magic;
+  write_u4(0xCAFEBABE);
+
+  // JVMSpec|           u2 minor_version;
+  // JVMSpec|           u2 major_version;
+  write_u2(ikh()->minor_version());
+  u2 major = ikh()->major_version();
+  write_u2(major);
+
+  // JVMSpec|           u2 constant_pool_count;
+  // JVMSpec|           cp_info constant_pool[constant_pool_count-1];
+  write_u2(cpool()->length());
+  copy_cpool_bytes(writeable_address(cpool_size()));
+
+  // JVMSpec|           u2 access_flags;
+  write_u2(ikh()->access_flags().get_flags() & JVM_RECOGNIZED_CLASS_MODIFIERS);
+
+  // JVMSpec|           u2 this_class;
+  // JVMSpec|           u2 super_class;
+  write_u2(class_symbol_to_cpool_index(ikh()->name()));
+  klassOop super_class = ikh()->super();
+  write_u2(super_class == NULL? 0 :  // zero for java.lang.Object
+                class_symbol_to_cpool_index(super_class->klass_part()->name()));
+
+  // JVMSpec|           u2 interfaces_count;
+  // JVMSpec|           u2 interfaces[interfaces_count];
+  objArrayHandle interfaces(thread(), ikh()->local_interfaces());
+  int num_interfaces = interfaces->length();
+  write_u2(num_interfaces);
+  for (int index = 0; index < num_interfaces; index++) {
+    HandleMark hm(thread());
+    instanceKlassHandle iikh(thread(), klassOop(interfaces->obj_at(index)));
+    write_u2(class_symbol_to_cpool_index(iikh->name()));
+  }
+
+  // JVMSpec|           u2 fields_count;
+  // JVMSpec|           field_info fields[fields_count];
+  write_field_infos();
+
+  // JVMSpec|           u2 methods_count;
+  // JVMSpec|           method_info methods[methods_count];
+  write_method_infos();
+
+  // JVMSpec|           u2 attributes_count;
+  // JVMSpec|           attribute_info attributes[attributes_count];
+  // JVMSpec|   } /* end ClassFile 8?
+  write_class_attributes();
+}
+
+address JvmtiClassFileReconstituter::writeable_address(size_t size) {
+  size_t used_size = _buffer_ptr - _buffer;
+  if (size + used_size >= _buffer_size) {
+    // compute the new buffer size: must be at least twice as big as before
+    // plus whatever new is being used; then convert to nice clean block boundary
+    size_t new_buffer_size = (size + _buffer_size*2 + 1) / initial_buffer_size
+                                                         * initial_buffer_size;
+
+    // VM goes belly-up if the memory isn't available, so cannot do OOM processing
+    _buffer = REALLOC_RESOURCE_ARRAY(u1, _buffer, _buffer_size, new_buffer_size);
+    _buffer_size = new_buffer_size;
+    _buffer_ptr = _buffer + used_size;
+  }
+  u1* ret_ptr = _buffer_ptr;
+  _buffer_ptr += size;
+  return ret_ptr;
+}
+
+void JvmtiClassFileReconstituter::write_attribute_name_index(const char* name) {
+  unsigned int hash_ignored;
+  symbolOop sym = SymbolTable::lookup_only(name, (int)strlen(name), hash_ignored);
+  assert(sym != NULL, "attribute name symbol not found");
+  u2 attr_name_index = symbol_to_cpool_index(sym);
+  assert(attr_name_index != 0, "attribute name symbol not in constant pool");
+  write_u2(attr_name_index);
+}
+
+void JvmtiClassFileReconstituter::write_u1(u1 x) {
+  *writeable_address(1) = x;
+}
+
+void JvmtiClassFileReconstituter::write_u2(u2 x) {
+  Bytes::put_Java_u2(writeable_address(2), x);
+}
+
+void JvmtiClassFileReconstituter::write_u4(u4 x) {
+  Bytes::put_Java_u4(writeable_address(4), x);
+}
+
+void JvmtiClassFileReconstituter::write_u8(u8 x) {
+  Bytes::put_Java_u8(writeable_address(8), x);
+}
+
+void JvmtiClassFileReconstituter::copy_bytecodes(methodHandle mh,
+                                                 unsigned char* bytecodes) {
+  // use a BytecodeStream to iterate over the bytecodes. JVM/fast bytecodes
+  // and the breakpoint bytecode are converted to their original bytecodes.
+
+  BytecodeStream bs(mh);
+
+  unsigned char* p = bytecodes;
+  Bytecodes::Code code;
+  bool is_rewritten = instanceKlass::cast(mh->method_holder())->is_rewritten();
+
+  while ((code = bs.next()) >= 0) {
+    assert(Bytecodes::is_java_code(code), "sanity check");
+    assert(code != Bytecodes::_breakpoint, "sanity check");
+
+    // length of bytecode (mnemonic + operands)
+    address bcp = bs.bcp();
+    int len = bs.next_bcp() - bcp;
+    assert(len > 0, "length must be > 0");
+
+    // copy the bytecodes
+    *p = (unsigned char) (bs.is_wide()? Bytecodes::_wide : code);
+    if (len > 1) {
+      memcpy(p+1, bcp+1, len-1);
+    }
+
+    // During linking the get/put and invoke instructions are rewritten
+    // with an index into the constant pool cache. The original constant
+    // pool index must be returned to caller.  Rewrite the index.
+    if (is_rewritten && len >= 3) {
+      switch (code) {
+      case Bytecodes::_getstatic       :  // fall through
+      case Bytecodes::_putstatic       :  // fall through
+      case Bytecodes::_getfield        :  // fall through
+      case Bytecodes::_putfield        :  // fall through
+      case Bytecodes::_invokevirtual   :  // fall through
+      case Bytecodes::_invokespecial   :  // fall through
+      case Bytecodes::_invokestatic    :  // fall through
+      case Bytecodes::_invokeinterface :
+        assert(len == 3 || (code == Bytecodes::_invokeinterface && len ==5),
+               "sanity check");
+        // cache cannot be pre-fetched since some classes won't have it yet
+        ConstantPoolCacheEntry* entry =
+          mh->constants()->cache()->entry_at(Bytes::get_native_u2(bcp+1));
+        int i = entry->constant_pool_index();
+        assert(i < mh->constants()->length(), "sanity check");
+        Bytes::put_Java_u2((address)(p+1), (u2)i);     // java byte ordering
+        break;
+      }
+    }
+
+    p += len;
+  }
+}