jdk

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/*
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 * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "classfile/stackMapTable.hpp"
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#include "classfile/verifier.hpp"
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#include "memory/resourceArea.hpp"
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#include "oops/constantPool.hpp"
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#include "oops/oop.inline.hpp"
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#include "runtime/handles.inline.hpp"
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StackMapTable::StackMapTable(StackMapReader* reader, StackMapFrame* init_frame,
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                             u2 max_locals, u2 max_stack,
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                             char* code_data, int code_len, TRAPS) {
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  _code_length = code_len;
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  _frame_count = reader->get_frame_count();
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  if (_frame_count > 0) {
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    _frame_array = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD,
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                                                StackMapFrame*, _frame_count);
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    StackMapFrame* pre_frame = init_frame;
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    for (int32_t i = 0; i < _frame_count; i++) {
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      StackMapFrame* frame = reader->next(
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        pre_frame, i == 0, max_locals, max_stack,
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        CHECK_VERIFY(pre_frame->verifier()));
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      _frame_array[i] = frame;
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      int offset = frame->offset();
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      if (offset >= code_len || code_data[offset] == 0) {
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        frame->verifier()->verify_error(
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            ErrorContext::bad_stackmap(i, frame),
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            "StackMapTable error: bad offset");
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        return;
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      }
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      pre_frame = frame;
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    }
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  }
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  reader->check_end(CHECK);
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}
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// This method is only called by method in StackMapTable.
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int StackMapTable::get_index_from_offset(int32_t offset) const {
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  int i = 0;
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  for (; i < _frame_count; i++) {
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    if (_frame_array[i]->offset() == offset) {
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      return i;
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    }
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  }
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  return i;  // frame with offset doesn't exist in the array
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}
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bool StackMapTable::match_stackmap(
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    StackMapFrame* frame, int32_t target,
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    bool match, bool update, ErrorContext* ctx, TRAPS) const {
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  int index = get_index_from_offset(target);
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  return match_stackmap(frame, target, index, match, update, ctx, THREAD);
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}
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// Match and/or update current_frame to the frame in stackmap table with
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// specified offset and frame index. Return true if the two frames match.
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//
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// The values of match and update are:                  _match__update
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//
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// checking a branch target:                             true   false
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// checking an exception handler:                        true   false
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// linear bytecode verification following an
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// unconditional branch:                                 false  true
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// linear bytecode verification not following an
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// unconditional branch:                                 true   true
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bool StackMapTable::match_stackmap(
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    StackMapFrame* frame, int32_t target, int32_t frame_index,
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    bool match, bool update, ErrorContext* ctx, TRAPS) const {
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  if (frame_index < 0 || frame_index >= _frame_count) {
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    *ctx = ErrorContext::missing_stackmap(frame->offset());
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    frame->verifier()->verify_error(
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        *ctx, "Expecting a stackmap frame at branch target %d", target);
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    return false;
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  }
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  StackMapFrame *stackmap_frame = _frame_array[frame_index];
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  bool result = true;
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  if (match) {
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    // Has direct control flow from last instruction, need to match the two
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    // frames.
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    result = frame->is_assignable_to(stackmap_frame,
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        ctx, CHECK_VERIFY_(frame->verifier(), result));
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  }
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  if (update) {
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    // Use the frame in stackmap table as current frame
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    int lsize = stackmap_frame->locals_size();
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    int ssize = stackmap_frame->stack_size();
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    if (frame->locals_size() > lsize || frame->stack_size() > ssize) {
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      // Make sure unused type array items are all _bogus_type.
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      frame->reset();
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    }
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    frame->set_locals_size(lsize);
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    frame->copy_locals(stackmap_frame);
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    frame->set_stack_size(ssize);
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    frame->copy_stack(stackmap_frame);
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    frame->set_flags(stackmap_frame->flags());
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  }
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  return result;
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}
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void StackMapTable::check_jump_target(
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    StackMapFrame* frame, int32_t target, TRAPS) const {
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  ErrorContext ctx;
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  bool match = match_stackmap(
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    frame, target, true, false, &ctx, CHECK_VERIFY(frame->verifier()));
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  if (!match || (target < 0 || target >= _code_length)) {
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    frame->verifier()->verify_error(ctx,
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        "Inconsistent stackmap frames at branch target %d", target);
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  }
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}
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void StackMapTable::print_on(outputStream* str) const {
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  str->indent().print_cr("StackMapTable: frame_count = %d", _frame_count);
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  str->indent().print_cr("table = { ");
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  {
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    streamIndentor si(str);
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    for (int32_t i = 0; i < _frame_count; ++i) {
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      _frame_array[i]->print_on(str);
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    }
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  }
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  str->print_cr(" }");
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}
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StackMapReader::StackMapReader(ClassVerifier* v, StackMapStream* stream, char* code_data,
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                               int32_t code_len, TRAPS) :
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                               _verifier(v), _stream(stream),
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                               _code_data(code_data), _code_length(code_len) {
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  methodHandle m = v->method();
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  if (m->has_stackmap_table()) {
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    _cp = constantPoolHandle(THREAD, m->constants());
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    _frame_count = _stream->get_u2(CHECK);
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  } else {
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    // There's no stackmap table present. Frame count and size are 0.
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    _frame_count = 0;
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  }
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}
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int32_t StackMapReader::chop(
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    VerificationType* locals, int32_t length, int32_t chops) {
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  if (locals == nullptr) return -1;
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  int32_t pos = length - 1;
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  for (int32_t i=0; i<chops; i++) {
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    if (locals[pos].is_category2_2nd()) {
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      pos -= 2;
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    } else {
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      pos --;
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    }
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    if (pos<0 && i<(chops-1)) return -1;
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  }
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  return pos+1;
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}
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#define CHECK_NT CHECK_(VerificationType::bogus_type())
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VerificationType StackMapReader::parse_verification_type(u1* flags, TRAPS) {
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  u1 tag = _stream->get_u1(CHECK_NT);
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  if (tag < (u1)ITEM_UninitializedThis) {
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    return VerificationType::from_tag(tag);
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  }
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  if (tag == ITEM_Object) {
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    u2 class_index = _stream->get_u2(CHECK_NT);
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    int nconstants = _cp->length();
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    if ((class_index <= 0 || class_index >= nconstants) ||
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        (!_cp->tag_at(class_index).is_klass() &&
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         !_cp->tag_at(class_index).is_unresolved_klass())) {
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      _stream->stackmap_format_error("bad class index", THREAD);
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      return VerificationType::bogus_type();
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    }
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    return VerificationType::reference_type(_cp->klass_name_at(class_index));
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  }
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  if (tag == ITEM_UninitializedThis) {
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    if (flags != nullptr) {
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      *flags |= FLAG_THIS_UNINIT;
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    }
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    return VerificationType::uninitialized_this_type();
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  }
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  if (tag == ITEM_Uninitialized) {
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    u2 offset = _stream->get_u2(CHECK_NT);
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    if (offset >= _code_length ||
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        _code_data[offset] != ClassVerifier::NEW_OFFSET) {
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      _verifier->class_format_error(
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        "StackMapTable format error: bad offset for Uninitialized");
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      return VerificationType::bogus_type();
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    }
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    return VerificationType::uninitialized_type(offset);
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  }
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  _stream->stackmap_format_error("bad verification type", THREAD);
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  return VerificationType::bogus_type();
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}
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StackMapFrame* StackMapReader::next(
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    StackMapFrame* pre_frame, bool first, u2 max_locals, u2 max_stack, TRAPS) {
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  StackMapFrame* frame;
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  int offset;
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  VerificationType* locals = nullptr;
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  u1 frame_type = _stream->get_u1(CHECK_NULL);
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  if (frame_type < 64) {
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    // same_frame
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    if (first) {
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      offset = frame_type;
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      // Can't share the locals array since that is updated by the verifier.
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      if (pre_frame->locals_size() > 0) {
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        locals = NEW_RESOURCE_ARRAY_IN_THREAD(
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          THREAD, VerificationType, pre_frame->locals_size());
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      }
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    } else {
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      offset = pre_frame->offset() + frame_type + 1;
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      locals = pre_frame->locals();
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    }
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    frame = new StackMapFrame(
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      offset, pre_frame->flags(), pre_frame->locals_size(), 0,
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      max_locals, max_stack, locals, nullptr, _verifier);
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    if (first && locals != nullptr) {
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      frame->copy_locals(pre_frame);
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    }
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    return frame;
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  }
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  if (frame_type < 128) {
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    // same_locals_1_stack_item_frame
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    if (first) {
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      offset = frame_type - 64;
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      // Can't share the locals array since that is updated by the verifier.
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      if (pre_frame->locals_size() > 0) {
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        locals = NEW_RESOURCE_ARRAY_IN_THREAD(
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          THREAD, VerificationType, pre_frame->locals_size());
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      }
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    } else {
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      offset = pre_frame->offset() + frame_type - 63;
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      locals = pre_frame->locals();
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    }
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    VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
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      THREAD, VerificationType, 2);
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    u2 stack_size = 1;
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    stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
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    if (stack[0].is_category2()) {
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      stack[1] = stack[0].to_category2_2nd();
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      stack_size = 2;
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    }
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    check_verification_type_array_size(
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      stack_size, max_stack, CHECK_VERIFY_(_verifier, nullptr));
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    frame = new StackMapFrame(
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      offset, pre_frame->flags(), pre_frame->locals_size(), stack_size,
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      max_locals, max_stack, locals, stack, _verifier);
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    if (first && locals != nullptr) {
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      frame->copy_locals(pre_frame);
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    }
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    return frame;
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  }
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  u2 offset_delta = _stream->get_u2(CHECK_NULL);
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  if (frame_type < SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
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    // reserved frame types
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    _stream->stackmap_format_error(
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      "reserved frame type", CHECK_VERIFY_(_verifier, nullptr));
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  }
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  if (frame_type == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
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    // same_locals_1_stack_item_frame_extended
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    if (first) {
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      offset = offset_delta;
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      // Can't share the locals array since that is updated by the verifier.
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      if (pre_frame->locals_size() > 0) {
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        locals = NEW_RESOURCE_ARRAY_IN_THREAD(
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          THREAD, VerificationType, pre_frame->locals_size());
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      }
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    } else {
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      offset = pre_frame->offset() + offset_delta + 1;
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      locals = pre_frame->locals();
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    }
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    VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(
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      THREAD, VerificationType, 2);
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    u2 stack_size = 1;
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    stack[0] = parse_verification_type(nullptr, CHECK_VERIFY_(_verifier, nullptr));
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    if (stack[0].is_category2()) {
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      stack[1] = stack[0].to_category2_2nd();
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      stack_size = 2;
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    }
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    check_verification_type_array_size(
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      stack_size, max_stack, CHECK_VERIFY_(_verifier, nullptr));
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    frame = new StackMapFrame(
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      offset, pre_frame->flags(), pre_frame->locals_size(), stack_size,
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      max_locals, max_stack, locals, stack, _verifier);
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    if (first && locals != nullptr) {
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      frame->copy_locals(pre_frame);
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    }
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    return frame;
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  }
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  if (frame_type <= SAME_EXTENDED) {
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    // chop_frame or same_frame_extended
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    locals = pre_frame->locals();
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    int length = pre_frame->locals_size();
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    int chops = SAME_EXTENDED - frame_type;
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    int new_length = length;
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    u1 flags = pre_frame->flags();
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    if (chops != 0) {
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      new_length = chop(locals, length, chops);
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      check_verification_type_array_size(
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        new_length, max_locals, CHECK_VERIFY_(_verifier, nullptr));
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      // Recompute flags since uninitializedThis could have been chopped.
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      flags = 0;
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      for (int i=0; i<new_length; i++) {
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        if (locals[i].is_uninitialized_this()) {
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          flags |= FLAG_THIS_UNINIT;
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          break;
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        }
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      }
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    }
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    if (first) {
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      offset = offset_delta;
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      // Can't share the locals array since that is updated by the verifier.
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      if (new_length > 0) {
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        locals = NEW_RESOURCE_ARRAY_IN_THREAD(
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          THREAD, VerificationType, new_length);
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      } else {
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        locals = nullptr;
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      }
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    } else {
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      offset = pre_frame->offset() + offset_delta + 1;
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    }
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    frame = new StackMapFrame(
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      offset, flags, new_length, 0, max_locals, max_stack,
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      locals, nullptr, _verifier);
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    if (first && locals != nullptr) {
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      frame->copy_locals(pre_frame);
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    }
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    return frame;
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  } else if (frame_type < SAME_EXTENDED + 4) {
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    // append_frame
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    int appends = frame_type - SAME_EXTENDED;
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    int real_length = pre_frame->locals_size();
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    int new_length = real_length + appends*2;
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    locals = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, VerificationType, new_length);
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    VerificationType* pre_locals = pre_frame->locals();
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    int i;
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    for (i=0; i<pre_frame->locals_size(); i++) {
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      locals[i] = pre_locals[i];
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    }
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    u1 flags = pre_frame->flags();
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    for (i=0; i<appends; i++) {
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      locals[real_length] = parse_verification_type(&flags, CHECK_NULL);
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      if (locals[real_length].is_category2()) {
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        locals[real_length + 1] = locals[real_length].to_category2_2nd();
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        ++real_length;
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      }
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      ++real_length;
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    }
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    check_verification_type_array_size(
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      real_length, max_locals, CHECK_VERIFY_(_verifier, nullptr));
374
    if (first) {
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      offset = offset_delta;
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    } else {
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      offset = pre_frame->offset() + offset_delta + 1;
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    }
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    frame = new StackMapFrame(
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      offset, flags, real_length, 0, max_locals,
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      max_stack, locals, nullptr, _verifier);
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    return frame;
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  }
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  if (frame_type == FULL) {
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    // full_frame
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    u1 flags = 0;
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    u2 locals_size = _stream->get_u2(CHECK_NULL);
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    int real_locals_size = 0;
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    if (locals_size > 0) {
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      locals = NEW_RESOURCE_ARRAY_IN_THREAD(
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        THREAD, VerificationType, locals_size*2);
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    }
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    int i;
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    for (i=0; i<locals_size; i++) {
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      locals[real_locals_size] = parse_verification_type(&flags, CHECK_NULL);
396
      if (locals[real_locals_size].is_category2()) {
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        locals[real_locals_size + 1] =
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          locals[real_locals_size].to_category2_2nd();
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        ++real_locals_size;
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      }
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      ++real_locals_size;
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    }
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    check_verification_type_array_size(
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      real_locals_size, max_locals, CHECK_VERIFY_(_verifier, nullptr));
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    u2 stack_size = _stream->get_u2(CHECK_NULL);
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    int real_stack_size = 0;
407
    VerificationType* stack = nullptr;
408
    if (stack_size > 0) {
409
      stack = NEW_RESOURCE_ARRAY_IN_THREAD(
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        THREAD, VerificationType, stack_size*2);
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    }
412
    for (i=0; i<stack_size; i++) {
413
      stack[real_stack_size] = parse_verification_type(nullptr, CHECK_NULL);
414
      if (stack[real_stack_size].is_category2()) {
415
        stack[real_stack_size + 1] = stack[real_stack_size].to_category2_2nd();
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        ++real_stack_size;
417
      }
418
      ++real_stack_size;
419
    }
420
    check_verification_type_array_size(
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      real_stack_size, max_stack, CHECK_VERIFY_(_verifier, nullptr));
422
    if (first) {
423
      offset = offset_delta;
424
    } else {
425
      offset = pre_frame->offset() + offset_delta + 1;
426
    }
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    frame = new StackMapFrame(
428
      offset, flags, real_locals_size, real_stack_size,
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      max_locals, max_stack, locals, stack, _verifier);
430
    return frame;
431
  }
432

433
  _stream->stackmap_format_error(
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    "reserved frame type", CHECK_VERIFY_(pre_frame->verifier(), nullptr));
435
  return nullptr;
436
}
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