/*
 * Copyright (c) 1998, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "cds/cdsConfig.hpp"
#include "classfile/classFileStream.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/stackMapTable.hpp"
#include "classfile/stackMapFrame.hpp"
#include "classfile/stackMapTableFormat.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/verifier.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "interpreter/bytecodes.hpp"
#include "interpreter/bytecodeStream.hpp"
#include "jvm.h"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/constantPool.inline.hpp"
#include "oops/instanceKlass.inline.hpp"
#include "oops/klass.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/typeArrayOop.hpp"
#include "runtime/arguments.hpp"
#include "runtime/fieldDescriptor.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/jniHandles.inline.hpp"
#include "runtime/os.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "services/threadService.hpp"
#include "utilities/align.hpp"
#include "utilities/bytes.hpp"
#if INCLUDE_CDS
#include "classfile/systemDictionaryShared.hpp"
#endif

#define NOFAILOVER_MAJOR_VERSION                       51
#define NONZERO_PADDING_BYTES_IN_SWITCH_MAJOR_VERSION  51
#define STATIC_METHOD_IN_INTERFACE_MAJOR_VERSION       52
#define MAX_ARRAY_DIMENSIONS 255

// Access to external entry for VerifyClassForMajorVersion - old byte code verifier

extern "C" {
  typedef jboolean (*verify_byte_codes_fn_t)(JNIEnv *, jclass, char *, jint, jint);
}

static verify_byte_codes_fn_t volatile _verify_byte_codes_fn = nullptr;

static verify_byte_codes_fn_t verify_byte_codes_fn() {

  if (_verify_byte_codes_fn != nullptr)
    return _verify_byte_codes_fn;

  MutexLocker locker(Verify_lock);

  if (_verify_byte_codes_fn != nullptr)
    return _verify_byte_codes_fn;

  void *lib_handle = nullptr;
  // Load verify dll
  if (is_vm_statically_linked()) {
    lib_handle = os::get_default_process_handle();
  } else {
    char buffer[JVM_MAXPATHLEN];
    char ebuf[1024];
    if (!os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), "verify"))
      return nullptr; // Caller will throw VerifyError

    lib_handle = os::dll_load(buffer, ebuf, sizeof(ebuf));
    if (lib_handle == nullptr)
      return nullptr; // Caller will throw VerifyError
  }

  void *fn = os::dll_lookup(lib_handle, "VerifyClassForMajorVersion");
  if (fn == nullptr)
    return nullptr; // Caller will throw VerifyError

  return _verify_byte_codes_fn = CAST_TO_FN_PTR(verify_byte_codes_fn_t, fn);
}


// Methods in Verifier

// This method determines whether we run the verifier and class file format checking code.
bool Verifier::should_verify_for(oop class_loader) {
  return class_loader == nullptr ?
    BytecodeVerificationLocal : BytecodeVerificationRemote;
}

// This method determines whether we allow package access in access checks in reflection.
bool Verifier::relax_access_for(oop loader) {
  bool trusted = java_lang_ClassLoader::is_trusted_loader(loader);
  bool need_verify =
    // verifyAll
    (BytecodeVerificationLocal && BytecodeVerificationRemote) ||
    // verifyRemote
    (!BytecodeVerificationLocal && BytecodeVerificationRemote && !trusted);
  return !need_verify;
}

// Callers will pass should_verify_class as true, depending on the results of should_verify_for() above,
// or pass true for redefinition of any class.
static bool is_eligible_for_verification(InstanceKlass* klass, bool should_verify_class) {
  Symbol* name = klass->name();

  return (should_verify_class &&
    // Can not verify the bytecodes for shared classes because they have
    // already been rewritten to contain constant pool cache indices,
    // which the verifier can't understand.
    // Shared classes shouldn't have stackmaps either.
    // However, bytecodes for shared old classes can be verified because
    // they have not been rewritten.
    !(klass->is_shared() && klass->is_rewritten()));
}

void Verifier::trace_class_resolution(Klass* resolve_class, InstanceKlass* verify_class) {
  assert(verify_class != nullptr, "Unexpected null verify_class");
  ResourceMark rm;
  Symbol* s = verify_class->source_file_name();
  const char* source_file = (s != nullptr ? s->as_C_string() : nullptr);
  const char* verify = verify_class->external_name();
  const char* resolve = resolve_class->external_name();
  // print in a single call to reduce interleaving between threads
  if (source_file != nullptr) {
    log_debug(class, resolve)("%s %s %s (verification)", verify, resolve, source_file);
  } else {
    log_debug(class, resolve)("%s %s (verification)", verify, resolve);
  }
}

// Prints the end-verification message to the appropriate output.
void Verifier::log_end_verification(outputStream* st, const char* klassName, Symbol* exception_name, oop pending_exception) {
  if (pending_exception != nullptr) {
    st->print("Verification for %s has", klassName);
    oop message = java_lang_Throwable::message(pending_exception);
    if (message != nullptr) {
      char* ex_msg = java_lang_String::as_utf8_string(message);
      st->print_cr(" exception pending '%s %s'",
                   pending_exception->klass()->external_name(), ex_msg);
    } else {
      st->print_cr(" exception pending %s ",
                   pending_exception->klass()->external_name());
    }
  } else if (exception_name != nullptr) {
    st->print_cr("Verification for %s failed", klassName);
  }
  st->print_cr("End class verification for: %s", klassName);
}

bool Verifier::verify(InstanceKlass* klass, bool should_verify_class, TRAPS) {
  HandleMark hm(THREAD);
  ResourceMark rm(THREAD);

  // Eagerly allocate the identity hash code for a klass. This is a fallout
  // from 6320749 and 8059924: hash code generator is not supposed to be called
  // during the safepoint, but it allows to sneak the hashcode in during
  // verification. Without this eager hashcode generation, we may end up
  // installing the hashcode during some other operation, which may be at
  // safepoint -- blowing up the checks. It was previously done as the side
  // effect (sic!) for external_name(), but instead of doing that, we opt to
  // explicitly push the hashcode in here. This is signify the following block
  // is IMPORTANT:
  if (klass->java_mirror() != nullptr) {
    klass->java_mirror()->identity_hash();
  }

  if (!is_eligible_for_verification(klass, should_verify_class)) {
    return true;
  }

  // Timer includes any side effects of class verification (resolution,
  // etc), but not recursive calls to Verifier::verify().
  JavaThread* jt = THREAD;
  PerfClassTraceTime timer(ClassLoader::perf_class_verify_time(),
                           ClassLoader::perf_class_verify_selftime(),
                           ClassLoader::perf_classes_verified(),
                           jt->get_thread_stat()->perf_recursion_counts_addr(),
                           jt->get_thread_stat()->perf_timers_addr(),
                           PerfClassTraceTime::CLASS_VERIFY);

  // If the class should be verified, first see if we can use the split
  // verifier.  If not, or if verification fails and can failover, then
  // call the inference verifier.
  Symbol* exception_name = nullptr;
  const size_t message_buffer_len = klass->name()->utf8_length() + 1024;
  char* message_buffer = nullptr;
  char* exception_message = nullptr;

  log_info(class, init)("Start class verification for: %s", klass->external_name());
  if (klass->major_version() >= STACKMAP_ATTRIBUTE_MAJOR_VERSION) {
    ClassVerifier split_verifier(jt, klass);
    // We don't use CHECK here, or on inference_verify below, so that we can log any exception.
    split_verifier.verify_class(THREAD);
    exception_name = split_verifier.result();

    // If dumping {classic, final} static archive, don't bother to run the old verifier, as
    // the class will be excluded from the archive anyway.
    bool can_failover = !(CDSConfig::is_dumping_classic_static_archive() || CDSConfig::is_dumping_final_static_archive()) &&
      klass->major_version() < NOFAILOVER_MAJOR_VERSION;

    if (can_failover && !HAS_PENDING_EXCEPTION &&  // Split verifier doesn't set PENDING_EXCEPTION for failure
        (exception_name == vmSymbols::java_lang_VerifyError() ||
         exception_name == vmSymbols::java_lang_ClassFormatError())) {
      log_info(verification)("Fail over class verification to old verifier for: %s", klass->external_name());
      log_info(class, init)("Fail over class verification to old verifier for: %s", klass->external_name());
#if INCLUDE_CDS
      // Exclude any classes that are verified with the old verifier, as the old verifier
      // doesn't call SystemDictionaryShared::add_verification_constraint()
      if (CDSConfig::is_dumping_archive()) {
        SystemDictionaryShared::warn_excluded(klass, "Verified with old verifier");
        SystemDictionaryShared::set_excluded(klass);
      }
#endif
      message_buffer = NEW_RESOURCE_ARRAY(char, message_buffer_len);
      exception_message = message_buffer;
      exception_name = inference_verify(
        klass, message_buffer, message_buffer_len, THREAD);
    }
    if (exception_name != nullptr) {
      exception_message = split_verifier.exception_message();
    }
  } else {
    message_buffer = NEW_RESOURCE_ARRAY(char, message_buffer_len);
    exception_message = message_buffer;
    exception_name = inference_verify(
        klass, message_buffer, message_buffer_len, THREAD);
  }

  LogTarget(Info, class, init) lt1;
  if (lt1.is_enabled()) {
    LogStream ls(lt1);
    log_end_verification(&ls, klass->external_name(), exception_name, PENDING_EXCEPTION);
  }
  LogTarget(Info, verification) lt2;
  if (lt2.is_enabled()) {
    LogStream ls(lt2);
    log_end_verification(&ls, klass->external_name(), exception_name, PENDING_EXCEPTION);
  }

  if (HAS_PENDING_EXCEPTION) {
    return false; // use the existing exception
  } else if (exception_name == nullptr) {
    return true; // verification succeeded
  } else { // VerifyError or ClassFormatError to be created and thrown
    Klass* kls =
      SystemDictionary::resolve_or_fail(exception_name, true, CHECK_false);
    if (log_is_enabled(Debug, class, resolve)) {
      Verifier::trace_class_resolution(kls, klass);
    }

    while (kls != nullptr) {
      if (kls == klass) {
        // If the class being verified is the exception we're creating
        // or one of it's superclasses, we're in trouble and are going
        // to infinitely recurse when we try to initialize the exception.
        // So bail out here by throwing the preallocated VM error.
        THROW_OOP_(Universe::internal_error_instance(), false);
      }
      kls = kls->super();
    }
    if (message_buffer != nullptr) {
      message_buffer[message_buffer_len - 1] = '\0'; // just to be sure
    }
    assert(exception_message != nullptr, "");
    THROW_MSG_(exception_name, exception_message, false);
  }
}

Symbol* Verifier::inference_verify(
    InstanceKlass* klass, char* message, size_t message_len, TRAPS) {
  JavaThread* thread = THREAD;

  verify_byte_codes_fn_t verify_func = verify_byte_codes_fn();

  if (verify_func == nullptr) {
    jio_snprintf(message, message_len, "Could not link verifier");
    return vmSymbols::java_lang_VerifyError();
  }

  ResourceMark rm(thread);
  log_info(verification)("Verifying class %s with old format", klass->external_name());

  jclass cls = (jclass) JNIHandles::make_local(thread, klass->java_mirror());
  jint result;

  {
    HandleMark hm(thread);
    ThreadToNativeFromVM ttn(thread);
    // ThreadToNativeFromVM takes care of changing thread_state, so safepoint
    // code knows that we have left the VM
    JNIEnv *env = thread->jni_environment();
    result = (*verify_func)(env, cls, message, (int)message_len, klass->major_version());
  }

  JNIHandles::destroy_local(cls);

  // These numbers are chosen so that VerifyClassCodes interface doesn't need
  // to be changed (still return jboolean (unsigned char)), and result is
  // 1 when verification is passed.
  if (result == 0) {
    return vmSymbols::java_lang_VerifyError();
  } else if (result == 1) {
    return nullptr; // verified.
  } else if (result == 2) {
    THROW_MSG_(vmSymbols::java_lang_OutOfMemoryError(), message, nullptr);
  } else if (result == 3) {
    return vmSymbols::java_lang_ClassFormatError();
  } else {
    ShouldNotReachHere();
    return nullptr;
  }
}

TypeOrigin TypeOrigin::null() {
  return TypeOrigin();
}
TypeOrigin TypeOrigin::local(int index, StackMapFrame* frame) {
  assert(frame != nullptr, "Must have a frame");
  return TypeOrigin(CF_LOCALS, index, StackMapFrame::copy(frame),
     frame->local_at(index));
}
TypeOrigin TypeOrigin::stack(int index, StackMapFrame* frame) {
  assert(frame != nullptr, "Must have a frame");
  return TypeOrigin(CF_STACK, index, StackMapFrame::copy(frame),
      frame->stack_at(index));
}
TypeOrigin TypeOrigin::sm_local(int index, StackMapFrame* frame) {
  assert(frame != nullptr, "Must have a frame");
  return TypeOrigin(SM_LOCALS, index, StackMapFrame::copy(frame),
      frame->local_at(index));
}
TypeOrigin TypeOrigin::sm_stack(int index, StackMapFrame* frame) {
  assert(frame != nullptr, "Must have a frame");
  return TypeOrigin(SM_STACK, index, StackMapFrame::copy(frame),
      frame->stack_at(index));
}
TypeOrigin TypeOrigin::bad_index(int index) {
  return TypeOrigin(BAD_INDEX, index, nullptr, VerificationType::bogus_type());
}
TypeOrigin TypeOrigin::cp(int index, VerificationType vt) {
  return TypeOrigin(CONST_POOL, index, nullptr, vt);
}
TypeOrigin TypeOrigin::signature(VerificationType vt) {
  return TypeOrigin(SIG, 0, nullptr, vt);
}
TypeOrigin TypeOrigin::implicit(VerificationType t) {
  return TypeOrigin(IMPLICIT, 0, nullptr, t);
}
TypeOrigin TypeOrigin::frame(StackMapFrame* frame) {
  return TypeOrigin(FRAME_ONLY, 0, StackMapFrame::copy(frame),
                    VerificationType::bogus_type());
}

void TypeOrigin::reset_frame() {
  if (_frame != nullptr) {
    _frame->restore();
  }
}

void TypeOrigin::details(outputStream* ss) const {
  _type.print_on(ss);
  switch (_origin) {
    case CF_LOCALS:
      ss->print(" (current frame, locals[%d])", _index);
      break;
    case CF_STACK:
      ss->print(" (current frame, stack[%d])", _index);
      break;
    case SM_LOCALS:
      ss->print(" (stack map, locals[%d])", _index);
      break;
    case SM_STACK:
      ss->print(" (stack map, stack[%d])", _index);
      break;
    case CONST_POOL:
      ss->print(" (constant pool %d)", _index);
      break;
    case SIG:
      ss->print(" (from method signature)");
      break;
    case IMPLICIT:
    case FRAME_ONLY:
    case NONE:
    default:
      ;
  }
}

#ifdef ASSERT
void TypeOrigin::print_on(outputStream* str) const {
  str->print("{%d,%d,%p:", _origin, _index, _frame);
  if (_frame != nullptr) {
    _frame->print_on(str);
  } else {
    str->print("null");
  }
  str->print(",");
  _type.print_on(str);
  str->print("}");
}
#endif

void ErrorContext::details(outputStream* ss, const Method* method) const {
  if (is_valid()) {
    ss->cr();
    ss->print_cr("Exception Details:");
    location_details(ss, method);
    reason_details(ss);
    frame_details(ss);
    bytecode_details(ss, method);
    handler_details(ss, method);
    stackmap_details(ss, method);
  }
}

void ErrorContext::reason_details(outputStream* ss) const {
  StreamIndentor si(ss, 2);
  ss->print_cr("Reason:");

  StreamIndentor si2(ss, 2);
  switch (_fault) {
    case INVALID_BYTECODE:
      ss->print("Error exists in the bytecode");
      break;
    case WRONG_TYPE:
      if (_expected.is_valid()) {
        ss->print("Type ");
        _type.details(ss);
        ss->print(" is not assignable to ");
        _expected.details(ss);
      } else {
        ss->print("Invalid type: ");
        _type.details(ss);
      }
      break;
    case FLAGS_MISMATCH:
      if (_expected.is_valid()) {
        ss->print("Current frame's flags are not assignable "
                  "to stack map frame's.");
      } else {
        ss->print("Current frame's flags are invalid in this context.");
      }
      break;
    case BAD_CP_INDEX:
      ss->print("Constant pool index %d is invalid", _type.index());
      break;
    case BAD_LOCAL_INDEX:
      ss->print("Local index %d is invalid", _type.index());
      break;
    case LOCALS_SIZE_MISMATCH:
      ss->print("Current frame's local size doesn't match stackmap.");
      break;
    case STACK_SIZE_MISMATCH:
      ss->print("Current frame's stack size doesn't match stackmap.");
      break;
    case STACK_OVERFLOW:
      ss->print("Exceeded max stack size.");
      break;
    case STACK_UNDERFLOW:
      ss->print("Attempt to pop empty stack.");
      break;
    case MISSING_STACKMAP:
      ss->print("Expected stackmap frame at this location.");
      break;
    case BAD_STACKMAP:
      ss->print("Invalid stackmap specification.");
      break;
    case UNKNOWN:
    default:
      ShouldNotReachHere();
      ss->print_cr("Unknown");
  }
  ss->cr();
}

void ErrorContext::location_details(outputStream* ss, const Method* method) const {
  if (_bci != -1 && method != nullptr) {
    const char* bytecode_name = "<invalid>";
    if (method->validate_bci(_bci) != -1) {
      Bytecodes::Code code = Bytecodes::code_or_bp_at(method->bcp_from(_bci));
      if (Bytecodes::is_defined(code)) {
          bytecode_name = Bytecodes::name(code);
      } else {
          bytecode_name = "<illegal>";
      }
    }
    InstanceKlass* ik = method->method_holder();

    StreamIndentor si(ss, 2);
    ss->print_cr("Location:");

    StreamIndentor si2(ss, 2);
    ss->print_cr("%s.%s%s @%d: %s",
        ik->name()->as_C_string(), method->name()->as_C_string(),
        method->signature()->as_C_string(), _bci, bytecode_name);
  }
}

void ErrorContext::frame_details(outputStream* ss) const {
  StreamIndentor si(ss, 2);
  if (_type.is_valid() && _type.frame() != nullptr) {
    ss->print_cr("Current Frame:");
    StreamIndentor si2(ss, 2);
    _type.frame()->print_on(ss);
  }
  if (_expected.is_valid() && _expected.frame() != nullptr) {
    ss->print_cr("Stackmap Frame:");
    StreamIndentor si2(ss, 2);
    _expected.frame()->print_on(ss);
  }
}

void ErrorContext::bytecode_details(outputStream* ss, const Method* method) const {
  if (method != nullptr) {
    StreamIndentor si(ss, 2);
    ss->print_cr("Bytecode:");
    StreamIndentor si2(ss, 2);
    ss->print_data(method->code_base(), method->code_size(), false);
  }
}

void ErrorContext::handler_details(outputStream* ss, const Method* method) const {
  if (method != nullptr) {
    StreamIndentor si(ss, 2);

    ExceptionTable table(method);
    if (table.length() > 0) {
      ss->print_cr("Exception Handler Table:");
      StreamIndentor si2(ss, 2);
      for (int i = 0; i < table.length(); ++i) {
        ss->print_cr("bci [%d, %d] => handler: %d", table.start_pc(i),
            table.end_pc(i), table.handler_pc(i));
      }
    }
  }
}

void ErrorContext::stackmap_details(outputStream* ss, const Method* method) const {
  if (method != nullptr && method->has_stackmap_table()) {
    StreamIndentor si(ss, 2);
    ss->print_cr("Stackmap Table:");
    Array<u1>* data = method->stackmap_data();
    stack_map_table* sm_table =
        stack_map_table::at((address)data->adr_at(0));
    stack_map_frame* sm_frame = sm_table->entries();
    StreamIndentor si2(ss, 2);
    int current_offset = -1;
    address end_of_sm_table = (address)sm_table + method->stackmap_data()->length();
    for (u2 i = 0; i < sm_table->number_of_entries(); ++i) {
      if (!sm_frame->verify((address)sm_frame, end_of_sm_table)) {
        sm_frame->print_truncated(ss, current_offset);
        return;
      }
      sm_frame->print_on(ss, current_offset);
      ss->cr();
      current_offset += sm_frame->offset_delta();
      sm_frame = sm_frame->next();
    }
  }
}

// Methods in ClassVerifier

ClassVerifier::ClassVerifier(JavaThread* current, InstanceKlass* klass)
    : _thread(current), _previous_symbol(nullptr), _symbols(nullptr), _exception_type(nullptr),
      _message(nullptr), _klass(klass) {
  _this_type = VerificationType::reference_type(klass->name());
}

ClassVerifier::~ClassVerifier() {
  // Decrement the reference count for any symbols created.
  if (_symbols != nullptr) {
    for (int i = 0; i < _symbols->length(); i++) {
      Symbol* s = _symbols->at(i);
      s->decrement_refcount();
    }
  }
}

VerificationType ClassVerifier::object_type() const {
  return VerificationType::reference_type(vmSymbols::java_lang_Object());
}

TypeOrigin ClassVerifier::ref_ctx(const char* sig) {
  VerificationType vt = VerificationType::reference_type(
                         create_temporary_symbol(sig, (int)strlen(sig)));
  return TypeOrigin::implicit(vt);
}


void ClassVerifier::verify_class(TRAPS) {
  log_info(verification)("Verifying class %s with new format", _klass->external_name());

  // Either verifying both local and remote classes or just remote classes.
  assert(BytecodeVerificationRemote, "Should not be here");

  Array<Method*>* methods = _klass->methods();
  int num_methods = methods->length();

  for (int index = 0; index < num_methods; index++) {
    // Check for recursive re-verification before each method.
    if (was_recursively_verified()) return;

    Method* m = methods->at(index);
    if (m->is_native() || m->is_abstract() || m->is_overpass()) {
      // If m is native or abstract, skip it.  It is checked in class file
      // parser that methods do not override a final method.  Overpass methods
      // are trusted since the VM generates them.
      continue;
    }
    verify_method(methodHandle(THREAD, m), CHECK_VERIFY(this));
  }

  if (was_recursively_verified()){
    log_info(verification)("Recursive verification detected for: %s", _klass->external_name());
    log_info(class, init)("Recursive verification detected for: %s",
                        _klass->external_name());
  }
}

// Translate the signature entries into verification types and save them in
// the growable array.  Also, save the count of arguments.
void ClassVerifier::translate_signature(Symbol* const method_sig,
                                        sig_as_verification_types* sig_verif_types) {
  SignatureStream sig_stream(method_sig);
  VerificationType sig_type[2];
  int sig_i = 0;
  GrowableArray<VerificationType>* verif_types = sig_verif_types->sig_verif_types();

  // Translate the signature arguments into verification types.
  while (!sig_stream.at_return_type()) {
    int n = change_sig_to_verificationType(&sig_stream, sig_type);
    assert(n <= 2, "Unexpected signature type");

    // Store verification type(s).  Longs and Doubles each have two verificationTypes.
    for (int x = 0; x < n; x++) {
      verif_types->push(sig_type[x]);
    }
    sig_i += n;
    sig_stream.next();
  }

  // Set final arg count, not including the return type.  The final arg count will
  // be compared with sig_verify_types' length to see if there is a return type.
  sig_verif_types->set_num_args(sig_i);

  // Store verification type(s) for the return type, if there is one.
  if (sig_stream.type() != T_VOID) {
    int n = change_sig_to_verificationType(&sig_stream, sig_type);
    assert(n <= 2, "Unexpected signature return type");
    for (int y = 0; y < n; y++) {
      verif_types->push(sig_type[y]);
    }
  }
}

void ClassVerifier::create_method_sig_entry(sig_as_verification_types* sig_verif_types,
                                            int sig_index) {
  // Translate the signature into verification types.
  ConstantPool* cp = _klass->constants();
  Symbol* const method_sig = cp->symbol_at(sig_index);
  translate_signature(method_sig, sig_verif_types);

  // Add the list of this signature's verification types to the table.
  bool is_unique = method_signatures_table()->put(sig_index, sig_verif_types);
  assert(is_unique, "Duplicate entries in method_signature_table");
}

void ClassVerifier::verify_method(const methodHandle& m, TRAPS) {
  HandleMark hm(THREAD);
  _method = m;   // initialize _method
  log_info(verification)("Verifying method %s", m->name_and_sig_as_C_string());

// For clang, the only good constant format string is a literal constant format string.
#define bad_type_msg "Bad type on operand stack in %s"

  u2 max_stack = m->verifier_max_stack();
  u2 max_locals = m->max_locals();
  constantPoolHandle cp(THREAD, m->constants());

  // Method signature was checked in ClassFileParser.
  assert(SignatureVerifier::is_valid_method_signature(m->signature()),
         "Invalid method signature");

  // Initial stack map frame: offset is 0, stack is initially empty.
  StackMapFrame current_frame(max_locals, max_stack, this);
  // Set initial locals
  VerificationType return_type = current_frame.set_locals_from_arg( m, current_type());

  u2 stackmap_index = 0; // index to the stackmap array

  u4 code_length = m->code_size();

  // Scan the bytecode and map each instruction's start offset to a number.
  char* code_data = generate_code_data(m, code_length, CHECK_VERIFY(this));

  int ex_min = code_length;
  int ex_max = -1;
  // Look through each item on the exception table. Each of the fields must refer
  // to a legal instruction.
  if (was_recursively_verified()) return;
  verify_exception_handler_table(
    code_length, code_data, ex_min, ex_max, CHECK_VERIFY(this));

  // Look through each entry on the local variable table and make sure
  // its range of code array offsets is valid. (4169817)
  if (m->has_localvariable_table()) {
    verify_local_variable_table(code_length, code_data, CHECK_VERIFY(this));
  }

  Array<u1>* stackmap_data = m->stackmap_data();
  StackMapStream stream(stackmap_data);
  StackMapReader reader(this, &stream, code_data, code_length, &current_frame, max_locals, max_stack, THREAD);
  StackMapTable stackmap_table(&reader, CHECK_VERIFY(this));

  LogTarget(Debug, verification) lt;
  if (lt.is_enabled()) {
    LogStream ls(lt);
    stackmap_table.print_on(&ls);
  }

  RawBytecodeStream bcs(m);

  // Scan the byte code linearly from the start to the end
  bool no_control_flow = false; // Set to true when there is no direct control
                                // flow from current instruction to the next
                                // instruction in sequence

  Bytecodes::Code opcode;
  while (!bcs.is_last_bytecode()) {
    // Check for recursive re-verification before each bytecode.
    if (was_recursively_verified())  return;

    opcode = bcs.raw_next();
    int bci = bcs.bci();

    // Set current frame's offset to bci
    current_frame.set_offset(bci);
    current_frame.set_mark();

    // Make sure every offset in stackmap table point to the beginning to
    // an instruction. Match current_frame to stackmap_table entry with
    // the same offset if exists.
    stackmap_index = verify_stackmap_table(
      stackmap_index, bci, &current_frame, &stackmap_table,
      no_control_flow, CHECK_VERIFY(this));


    bool this_uninit = false;  // Set to true when invokespecial <init> initialized 'this'
    bool verified_exc_handlers = false;

    // Merge with the next instruction
    {
      VerificationType type, type2;
      VerificationType atype;

      LogTarget(Debug, verification) lt;
      if (lt.is_enabled()) {
        LogStream ls(lt);
        current_frame.print_on(&ls);
        lt.print("offset = %d,  opcode = %s", bci,
                 opcode == Bytecodes::_illegal ? "illegal" : Bytecodes::name(opcode));
      }

      // Make sure wide instruction is in correct format
      if (bcs.is_wide()) {
        if (opcode != Bytecodes::_iinc   && opcode != Bytecodes::_iload  &&
            opcode != Bytecodes::_aload  && opcode != Bytecodes::_lload  &&
            opcode != Bytecodes::_istore && opcode != Bytecodes::_astore &&
            opcode != Bytecodes::_lstore && opcode != Bytecodes::_fload  &&
            opcode != Bytecodes::_dload  && opcode != Bytecodes::_fstore &&
            opcode != Bytecodes::_dstore) {
          /* Unreachable?  RawBytecodeStream's raw_next() returns 'illegal'
           * if we encounter a wide instruction that modifies an invalid
           * opcode (not one of the ones listed above) */
          verify_error(ErrorContext::bad_code(bci), "Bad wide instruction");
          return;
        }
      }

      // Look for possible jump target in exception handlers and see if it
      // matches current_frame.  Do this check here for astore*, dstore*,
      // fstore*, istore*, and lstore* opcodes because they can change the type
      // state by adding a local.  JVM Spec says that the incoming type state
      // should be used for this check.  So, do the check here before a possible
      // local is added to the type state.
      if (Bytecodes::is_store_into_local(opcode) && bci >= ex_min && bci < ex_max) {
        if (was_recursively_verified()) return;
        verify_exception_handler_targets(
          bci, this_uninit, &current_frame, &stackmap_table, CHECK_VERIFY(this));
        verified_exc_handlers = true;
      }

      if (was_recursively_verified()) return;

      switch (opcode) {
        case Bytecodes::_nop :
          no_control_flow = false; break;
        case Bytecodes::_aconst_null :
          current_frame.push_stack(
            VerificationType::null_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_iconst_m1 :
        case Bytecodes::_iconst_0 :
        case Bytecodes::_iconst_1 :
        case Bytecodes::_iconst_2 :
        case Bytecodes::_iconst_3 :
        case Bytecodes::_iconst_4 :
        case Bytecodes::_iconst_5 :
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_lconst_0 :
        case Bytecodes::_lconst_1 :
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_fconst_0 :
        case Bytecodes::_fconst_1 :
        case Bytecodes::_fconst_2 :
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dconst_0 :
        case Bytecodes::_dconst_1 :
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_sipush :
        case Bytecodes::_bipush :
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_ldc :
          verify_ldc(
            opcode, bcs.get_index_u1(), &current_frame,
            cp, bci, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_ldc_w :
        case Bytecodes::_ldc2_w :
          verify_ldc(
            opcode, bcs.get_index_u2(), &current_frame,
            cp, bci, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_iload :
          verify_iload(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_iload_0 :
        case Bytecodes::_iload_1 :
        case Bytecodes::_iload_2 :
        case Bytecodes::_iload_3 : {
          int index = opcode - Bytecodes::_iload_0;
          verify_iload(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_lload :
          verify_lload(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_lload_0 :
        case Bytecodes::_lload_1 :
        case Bytecodes::_lload_2 :
        case Bytecodes::_lload_3 : {
          int index = opcode - Bytecodes::_lload_0;
          verify_lload(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_fload :
          verify_fload(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_fload_0 :
        case Bytecodes::_fload_1 :
        case Bytecodes::_fload_2 :
        case Bytecodes::_fload_3 : {
          int index = opcode - Bytecodes::_fload_0;
          verify_fload(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_dload :
          verify_dload(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dload_0 :
        case Bytecodes::_dload_1 :
        case Bytecodes::_dload_2 :
        case Bytecodes::_dload_3 : {
          int index = opcode - Bytecodes::_dload_0;
          verify_dload(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_aload :
          verify_aload(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_aload_0 :
        case Bytecodes::_aload_1 :
        case Bytecodes::_aload_2 :
        case Bytecodes::_aload_3 : {
          int index = opcode - Bytecodes::_aload_0;
          verify_aload(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_iaload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_int_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[I")),
                bad_type_msg, "iaload");
            return;
          }
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_baload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_bool_array() && !atype.is_byte_array()) {
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "baload");
            return;
          }
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_caload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_char_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[C")),
                bad_type_msg, "caload");
            return;
          }
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_saload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_short_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[S")),
                bad_type_msg, "saload");
            return;
          }
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_laload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_long_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[J")),
                bad_type_msg, "laload");
            return;
          }
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_faload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_float_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[F")),
                bad_type_msg, "faload");
            return;
          }
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_daload :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_double_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[D")),
                bad_type_msg, "daload");
            return;
          }
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_aaload : {
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_reference_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(),
                TypeOrigin::implicit(VerificationType::reference_check())),
                bad_type_msg, "aaload");
            return;
          }
          if (atype.is_null()) {
            current_frame.push_stack(
              VerificationType::null_type(), CHECK_VERIFY(this));
          } else {
            VerificationType component = atype.get_component(this);
            current_frame.push_stack(component, CHECK_VERIFY(this));
          }
          no_control_flow = false; break;
        }
        case Bytecodes::_istore :
          verify_istore(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_istore_0 :
        case Bytecodes::_istore_1 :
        case Bytecodes::_istore_2 :
        case Bytecodes::_istore_3 : {
          int index = opcode - Bytecodes::_istore_0;
          verify_istore(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_lstore :
          verify_lstore(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_lstore_0 :
        case Bytecodes::_lstore_1 :
        case Bytecodes::_lstore_2 :
        case Bytecodes::_lstore_3 : {
          int index = opcode - Bytecodes::_lstore_0;
          verify_lstore(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_fstore :
          verify_fstore(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_fstore_0 :
        case Bytecodes::_fstore_1 :
        case Bytecodes::_fstore_2 :
        case Bytecodes::_fstore_3 : {
          int index = opcode - Bytecodes::_fstore_0;
          verify_fstore(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_dstore :
          verify_dstore(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dstore_0 :
        case Bytecodes::_dstore_1 :
        case Bytecodes::_dstore_2 :
        case Bytecodes::_dstore_3 : {
          int index = opcode - Bytecodes::_dstore_0;
          verify_dstore(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_astore :
          verify_astore(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_astore_0 :
        case Bytecodes::_astore_1 :
        case Bytecodes::_astore_2 :
        case Bytecodes::_astore_3 : {
          int index = opcode - Bytecodes::_astore_0;
          verify_astore(index, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
          }
        case Bytecodes::_iastore :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_int_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[I")),
                bad_type_msg, "iastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_bastore :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_bool_array() && !atype.is_byte_array()) {
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "bastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_castore :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_char_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[C")),
                bad_type_msg, "castore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_sastore :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_short_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[S")),
                bad_type_msg, "sastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_lastore :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_long_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[J")),
                bad_type_msg, "lastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_fastore :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.pop_stack
            (VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_float_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[F")),
                bad_type_msg, "fastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_dastore :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!atype.is_double_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(), ref_ctx("[D")),
                bad_type_msg, "dastore");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_aastore :
          type = current_frame.pop_stack(object_type(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          atype = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          // more type-checking is done at runtime
          if (!atype.is_reference_array()) {
            verify_error(ErrorContext::bad_type(bci,
                current_frame.stack_top_ctx(),
                TypeOrigin::implicit(VerificationType::reference_check())),
                bad_type_msg, "aastore");
            return;
          }
          // 4938384: relaxed constraint in JVMS 3rd edition.
          no_control_flow = false; break;
        case Bytecodes::_pop :
          current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_pop2 :
          type = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type.is_category1()) {
            current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type.is_category2_2nd()) {
            current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable? Would need a category2_1st on TOS
             * which does not appear possible. */
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "pop2");
            return;
          }
          no_control_flow = false; break;
        case Bytecodes::_dup :
          type = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dup_x1 :
          type = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dup_x2 :
        {
          VerificationType type3;
          type = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type2.is_category1()) {
            type3 = current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type2.is_category2_2nd()) {
            type3 = current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable? Would need a category2_1st at stack depth 2 with
             * a category1 on TOS which does not appear possible. */
            verify_error(ErrorContext::bad_type(
                bci, current_frame.stack_top_ctx()), bad_type_msg, "dup_x2");
            return;
          }
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type3, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_dup2 :
          type = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type.is_category1()) {
            type2 = current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type.is_category2_2nd()) {
            type2 = current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable?  Would need a category2_1st on TOS which does not
             * appear possible. */
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "dup2");
            return;
          }
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dup2_x1 :
        {
          VerificationType type3;
          type = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type.is_category1()) {
            type2 = current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type.is_category2_2nd()) {
            type2 = current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable?  Would need a category2_1st on TOS which does
             * not appear possible. */
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "dup2_x1");
            return;
          }
          type3 = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type3, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_dup2_x2 :
        {
          VerificationType type3, type4;
          type = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type.is_category1()) {
            type2 = current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type.is_category2_2nd()) {
            type2 = current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable?  Would need a category2_1st on TOS which does
             * not appear possible. */
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "dup2_x2");
            return;
          }
          type3 = current_frame.pop_stack(CHECK_VERIFY(this));
          if (type3.is_category1()) {
            type4 = current_frame.pop_stack(
              VerificationType::category1_check(), CHECK_VERIFY(this));
          } else if (type3.is_category2_2nd()) {
            type4 = current_frame.pop_stack(
              VerificationType::category2_check(), CHECK_VERIFY(this));
          } else {
            /* Unreachable?  Would need a category2_1st on TOS after popping
             * a long/double or two category 1's, which does not
             * appear possible. */
            verify_error(
                ErrorContext::bad_type(bci, current_frame.stack_top_ctx()),
                bad_type_msg, "dup2_x2");
            return;
          }
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type4, CHECK_VERIFY(this));
          current_frame.push_stack(type3, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_swap :
          type = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          type2 = current_frame.pop_stack(
            VerificationType::category1_check(), CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          current_frame.push_stack(type2, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_iadd :
        case Bytecodes::_isub :
        case Bytecodes::_imul :
        case Bytecodes::_idiv :
        case Bytecodes::_irem :
        case Bytecodes::_ishl :
        case Bytecodes::_ishr :
        case Bytecodes::_iushr :
        case Bytecodes::_ior :
        case Bytecodes::_ixor :
        case Bytecodes::_iand :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_ineg :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_ladd :
        case Bytecodes::_lsub :
        case Bytecodes::_lmul :
        case Bytecodes::_ldiv :
        case Bytecodes::_lrem :
        case Bytecodes::_land :
        case Bytecodes::_lor :
        case Bytecodes::_lxor :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_lneg :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_lshl :
        case Bytecodes::_lshr :
        case Bytecodes::_lushr :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_fadd :
        case Bytecodes::_fsub :
        case Bytecodes::_fmul :
        case Bytecodes::_fdiv :
        case Bytecodes::_frem :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_fneg :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dadd :
        case Bytecodes::_dsub :
        case Bytecodes::_dmul :
        case Bytecodes::_ddiv :
        case Bytecodes::_drem :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_dneg :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_iinc :
          verify_iinc(bcs.get_index(), &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_i2l :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
       case Bytecodes::_l2i :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_i2f :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_i2d :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_l2f :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_l2d :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_f2i :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_f2l :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_f2d :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::double_type(),
            VerificationType::double2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_d2i :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_d2l :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.push_stack_2(
            VerificationType::long_type(),
            VerificationType::long2_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_d2f :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_i2b :
        case Bytecodes::_i2c :
        case Bytecodes::_i2s :
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_lcmp :
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.pop_stack_2(
            VerificationType::long2_type(),
            VerificationType::long_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_fcmpl :
        case Bytecodes::_fcmpg :
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_dcmpl :
        case Bytecodes::_dcmpg :
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.pop_stack_2(
            VerificationType::double2_type(),
            VerificationType::double_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_if_icmpeq:
        case Bytecodes::_if_icmpne:
        case Bytecodes::_if_icmplt:
        case Bytecodes::_if_icmpge:
        case Bytecodes::_if_icmpgt:
        case Bytecodes::_if_icmple:
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_ifeq:
        case Bytecodes::_ifne:
        case Bytecodes::_iflt:
        case Bytecodes::_ifge:
        case Bytecodes::_ifgt:
        case Bytecodes::_ifle:
          current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          stackmap_table.check_jump_target(
            &current_frame, bcs.bci(), bcs.get_offset_s2(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_if_acmpeq :
        case Bytecodes::_if_acmpne :
          current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          // fall through
        case Bytecodes::_ifnull :
        case Bytecodes::_ifnonnull :
          current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          stackmap_table.check_jump_target
            (&current_frame, bcs.bci(), bcs.get_offset_s2(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_goto :
          stackmap_table.check_jump_target(
            &current_frame, bcs.bci(), bcs.get_offset_s2(), CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_goto_w :
          stackmap_table.check_jump_target(
            &current_frame, bcs.bci(), bcs.get_offset_s4(), CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_tableswitch :
        case Bytecodes::_lookupswitch :
          verify_switch(
            &bcs, code_length, code_data, &current_frame,
            &stackmap_table, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_ireturn :
          type = current_frame.pop_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          verify_return_value(return_type, type, bci,
                              &current_frame, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_lreturn :
          type2 = current_frame.pop_stack(
            VerificationType::long2_type(), CHECK_VERIFY(this));
          type = current_frame.pop_stack(
            VerificationType::long_type(), CHECK_VERIFY(this));
          verify_return_value(return_type, type, bci,
                              &current_frame, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_freturn :
          type = current_frame.pop_stack(
            VerificationType::float_type(), CHECK_VERIFY(this));
          verify_return_value(return_type, type, bci,
                              &current_frame, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_dreturn :
          type2 = current_frame.pop_stack(
            VerificationType::double2_type(),  CHECK_VERIFY(this));
          type = current_frame.pop_stack(
            VerificationType::double_type(), CHECK_VERIFY(this));
          verify_return_value(return_type, type, bci,
                              &current_frame, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_areturn :
          type = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          verify_return_value(return_type, type, bci,
                              &current_frame, CHECK_VERIFY(this));
          no_control_flow = true; break;
        case Bytecodes::_return :
          if (return_type != VerificationType::bogus_type()) {
            verify_error(ErrorContext::bad_code(bci),
                         "Method expects a return value");
            return;
          }
          // Make sure "this" has been initialized if current method is an
          // <init>.
          if (_method->name() == vmSymbols::object_initializer_name() &&
              current_frame.flag_this_uninit()) {
            verify_error(ErrorContext::bad_code(bci),
                         "Constructor must call super() or this() "
                         "before return");
            return;
          }
          no_control_flow = true; break;
        case Bytecodes::_getstatic :
        case Bytecodes::_putstatic :
          // pass TRUE, operand can be an array type for getstatic/putstatic.
          verify_field_instructions(
            &bcs, &current_frame, cp, true, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_getfield :
        case Bytecodes::_putfield :
          // pass FALSE, operand can't be an array type for getfield/putfield.
          verify_field_instructions(
            &bcs, &current_frame, cp, false, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_invokevirtual :
        case Bytecodes::_invokespecial :
        case Bytecodes::_invokestatic :
          verify_invoke_instructions(
            &bcs, code_length, &current_frame, (bci >= ex_min && bci < ex_max),
            &this_uninit, return_type, cp, &stackmap_table, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_invokeinterface :
        case Bytecodes::_invokedynamic :
          verify_invoke_instructions(
            &bcs, code_length, &current_frame, (bci >= ex_min && bci < ex_max),
            &this_uninit, return_type, cp, &stackmap_table, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_new :
        {
          u2 index = bcs.get_index_u2();
          verify_cp_class_type(bci, index, cp, CHECK_VERIFY(this));
          VerificationType new_class_type =
            cp_index_to_type(index, cp, CHECK_VERIFY(this));
          if (!new_class_type.is_object()) {
            verify_error(ErrorContext::bad_type(bci,
                TypeOrigin::cp(index, new_class_type)),
                "Illegal new instruction");
            return;
          }
          type = VerificationType::uninitialized_type(checked_cast<u2>(bci));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_newarray :
          type = get_newarray_type(bcs.get_index(), bci, CHECK_VERIFY(this));
          current_frame.pop_stack(
            VerificationType::integer_type(),  CHECK_VERIFY(this));
          current_frame.push_stack(type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_anewarray :
          verify_anewarray(
            bci, bcs.get_index_u2(), cp, &current_frame, CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_arraylength :
          type = current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          if (!(type.is_null() || type.is_array())) {
            verify_error(ErrorContext::bad_type(
                bci, current_frame.stack_top_ctx()),
                bad_type_msg, "arraylength");
          }
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_checkcast :
        {
          u2 index = bcs.get_index_u2();
          verify_cp_class_type(bci, index, cp, CHECK_VERIFY(this));
          current_frame.pop_stack(object_type(), CHECK_VERIFY(this));
          VerificationType klass_type = cp_index_to_type(
            index, cp, CHECK_VERIFY(this));
          current_frame.push_stack(klass_type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_instanceof : {
          u2 index = bcs.get_index_u2();
          verify_cp_class_type(bci, index, cp, CHECK_VERIFY(this));
          current_frame.pop_stack(object_type(), CHECK_VERIFY(this));
          current_frame.push_stack(
            VerificationType::integer_type(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_monitorenter :
        case Bytecodes::_monitorexit :
          current_frame.pop_stack(
            VerificationType::reference_check(), CHECK_VERIFY(this));
          no_control_flow = false; break;
        case Bytecodes::_multianewarray :
        {
          u2 index = bcs.get_index_u2();
          u2 dim = *(bcs.bcp()+3);
          verify_cp_class_type(bci, index, cp, CHECK_VERIFY(this));
          VerificationType new_array_type =
            cp_index_to_type(index, cp, CHECK_VERIFY(this));
          if (!new_array_type.is_array()) {
            verify_error(ErrorContext::bad_type(bci,
                TypeOrigin::cp(index, new_array_type)),
                "Illegal constant pool index in multianewarray instruction");
            return;
          }
          if (dim < 1 || new_array_type.dimensions() < dim) {
            verify_error(ErrorContext::bad_code(bci),
                "Illegal dimension in multianewarray instruction: %d", dim);
            return;
          }
          for (int i = 0; i < dim; i++) {
            current_frame.pop_stack(
              VerificationType::integer_type(), CHECK_VERIFY(this));
          }
          current_frame.push_stack(new_array_type, CHECK_VERIFY(this));
          no_control_flow = false; break;
        }
        case Bytecodes::_athrow :
          type = VerificationType::reference_type(
            vmSymbols::java_lang_Throwable());
          current_frame.pop_stack(type, CHECK_VERIFY(this));
          no_control_flow = true; break;
        default:
          // We only need to check the valid bytecodes in class file.
          // And jsr and ret are not in the new class file format in JDK1.6.
          verify_error(ErrorContext::bad_code(bci),
              "Bad instruction: %02x", opcode);
          no_control_flow = false;
          return;
      }  // end switch
    }  // end Merge with the next instruction

    // Look for possible jump target in exception handlers and see if it matches
    // current_frame.  Don't do this check if it has already been done (for
    // ([a,d,f,i,l]store* opcodes).  This check cannot be done earlier because
    // opcodes, such as invokespecial, may set the this_uninit flag.
    assert(!(verified_exc_handlers && this_uninit),
      "Exception handler targets got verified before this_uninit got set");
    if (!verified_exc_handlers && bci >= ex_min && bci < ex_max) {
      if (was_recursively_verified()) return;
      verify_exception_handler_targets(
        bci, this_uninit, &current_frame, &stackmap_table, CHECK_VERIFY(this));
    }
  } // end while

  // Make sure that control flow does not fall through end of the method
  if (!no_control_flow) {
    verify_error(ErrorContext::bad_code(code_length),
        "Control flow falls through code end");
    return;
  }
}

#undef bad_type_message

char* ClassVerifier::generate_code_data(const methodHandle& m, u4 code_length, TRAPS) {
  char* code_data = NEW_RESOURCE_ARRAY(char, code_length);
  memset(code_data, 0, sizeof(char) * code_length);
  RawBytecodeStream bcs(m);

  while (!bcs.is_last_bytecode()) {
    if (bcs.raw_next() != Bytecodes::_illegal) {
      int bci = bcs.bci();
      if (bcs.raw_code() == Bytecodes::_new) {
        code_data[bci] = NEW_OFFSET;
      } else {
        code_data[bci] = BYTECODE_OFFSET;
      }
    } else {
      verify_error(ErrorContext::bad_code(bcs.bci()), "Bad instruction");
      return nullptr;
    }
  }

  return code_data;
}

// Since this method references the constant pool, call was_recursively_verified()
// before calling this method to make sure a prior class load did not cause the
// current class to get verified.
void ClassVerifier::verify_exception_handler_table(u4 code_length, char* code_data, int& min, int& max, TRAPS) {
  ExceptionTable exhandlers(_method());
  int exlength = exhandlers.length();
  constantPoolHandle cp (THREAD, _method->constants());

  for(int i = 0; i < exlength; i++) {
    u2 start_pc = exhandlers.start_pc(i);
    u2 end_pc = exhandlers.end_pc(i);
    u2 handler_pc = exhandlers.handler_pc(i);
    if (start_pc >= code_length || code_data[start_pc] == 0) {
      class_format_error("Illegal exception table start_pc %d", start_pc);
      return;
    }
    if (end_pc != code_length) {   // special case: end_pc == code_length
      if (end_pc > code_length || code_data[end_pc] == 0) {
        class_format_error("Illegal exception table end_pc %d", end_pc);
        return;
      }
    }
    if (handler_pc >= code_length || code_data[handler_pc] == 0) {
      class_format_error("Illegal exception table handler_pc %d", handler_pc);
      return;
    }
    u2 catch_type_index = exhandlers.catch_type_index(i);
    if (catch_type_index != 0) {
      VerificationType catch_type = cp_index_to_type(
        catch_type_index, cp, CHECK_VERIFY(this));
      VerificationType throwable =
        VerificationType::reference_type(vmSymbols::java_lang_Throwable());
      // If the catch type is Throwable pre-resolve it now as the assignable check won't
      // do that, and we need to avoid a runtime resolution in case we are trying to
      // catch OutOfMemoryError.
      if (cp->klass_name_at(catch_type_index) == vmSymbols::java_lang_Throwable()) {
        cp->klass_at(catch_type_index, CHECK);
      }
      bool is_subclass = throwable.is_assignable_from(
        catch_type, this, false, CHECK_VERIFY(this));
      if (!is_subclass) {
        // 4286534: should throw VerifyError according to recent spec change
        verify_error(ErrorContext::bad_type(handler_pc,
            TypeOrigin::cp(catch_type_index, catch_type),
            TypeOrigin::implicit(throwable)),
            "Catch type is not a subclass "
            "of Throwable in exception handler %d", handler_pc);
        return;
      }
    }
    if (start_pc < min) min = start_pc;
    if (end_pc > max) max = end_pc;
  }
}

void ClassVerifier::verify_local_variable_table(u4 code_length, char* code_data, TRAPS) {
  int localvariable_table_length = _method->localvariable_table_length();
  if (localvariable_table_length > 0) {
    LocalVariableTableElement* table = _method->localvariable_table_start();
    for (int i = 0; i < localvariable_table_length; i++) {
      u2 start_bci = table[i].start_bci;
      u2 length = table[i].length;

      if (start_bci >= code_length || code_data[start_bci] == 0) {
        class_format_error(
          "Illegal local variable table start_pc %d", start_bci);
        return;
      }
      u4 end_bci = (u4)(start_bci + length);
      if (end_bci != code_length) {
        if (end_bci >= code_length || code_data[end_bci] == 0) {
          class_format_error( "Illegal local variable table length %d", length);
          return;
        }
      }
    }
  }
}

u2 ClassVerifier::verify_stackmap_table(u2 stackmap_index, int bci,
                                        StackMapFrame* current_frame,
                                        StackMapTable* stackmap_table,
                                        bool no_control_flow, TRAPS) {
  if (stackmap_index < stackmap_table->get_frame_count()) {
    int this_offset = stackmap_table->get_offset(stackmap_index);
    if (no_control_flow && this_offset > bci) {
      verify_error(ErrorContext::missing_stackmap(bci),
                   "Expecting a stack map frame");
      return 0;
    }
    if (this_offset == bci) {
      ErrorContext ctx;
      // See if current stack map can be assigned to the frame in table.
      // current_frame is the stackmap frame got from the last instruction.
      // If matched, current_frame will be updated by this method.
      bool matches = stackmap_table->match_stackmap(
        current_frame, this_offset, stackmap_index,
        !no_control_flow, true, &ctx, CHECK_VERIFY_(this, 0));
      if (!matches) {
        // report type error
        verify_error(ctx, "Instruction type does not match stack map");
        return 0;
      }
      stackmap_index++;
    } else if (this_offset < bci) {
      // current_offset should have met this_offset.
      class_format_error("Bad stack map offset %d", this_offset);
      return 0;
    }
  } else if (no_control_flow) {
    verify_error(ErrorContext::bad_code(bci), "Expecting a stack map frame");
    return 0;
  }
  return stackmap_index;
}

// Since this method references the constant pool, call was_recursively_verified()
// before calling this method to make sure a prior class load did not cause the
// current class to get verified.
void ClassVerifier::verify_exception_handler_targets(int bci, bool this_uninit,
                                                     StackMapFrame* current_frame,
                                                     StackMapTable* stackmap_table, TRAPS) {
  constantPoolHandle cp (THREAD, _method->constants());
  ExceptionTable exhandlers(_method());
  int exlength = exhandlers.length();
  for(int i = 0; i < exlength; i++) {
    u2 start_pc = exhandlers.start_pc(i);
    u2 end_pc = exhandlers.end_pc(i);
    u2 handler_pc = exhandlers.handler_pc(i);
    int catch_type_index = exhandlers.catch_type_index(i);
    if(bci >= start_pc && bci < end_pc) {
      u1 flags = current_frame->flags();
      if (this_uninit) {  flags |= FLAG_THIS_UNINIT; }
      StackMapFrame* new_frame = current_frame->frame_in_exception_handler(flags);
      if (catch_type_index != 0) {
        if (was_recursively_verified()) return;
        // We know that this index refers to a subclass of Throwable
        VerificationType catch_type = cp_index_to_type(
          catch_type_index, cp, CHECK_VERIFY(this));
        new_frame->push_stack(catch_type, CHECK_VERIFY(this));
      } else {
        VerificationType throwable =
          VerificationType::reference_type(vmSymbols::java_lang_Throwable());
        new_frame->push_stack(throwable, CHECK_VERIFY(this));
      }
      ErrorContext ctx;
      bool matches = stackmap_table->match_stackmap(
        new_frame, handler_pc, true, false, &ctx, CHECK_VERIFY(this));
      if (!matches) {
        verify_error(ctx, "Stack map does not match the one at "
            "exception handler %d", handler_pc);
        return;
      }
    }
  }
}

void ClassVerifier::verify_cp_index(
    int bci, const constantPoolHandle& cp, u2 index, TRAPS) {
  int nconstants = cp->length();
  if ((index <= 0) || (index >= nconstants)) {
    verify_error(ErrorContext::bad_cp_index(bci, index),
        "Illegal constant pool index %d in class %s",
        index, cp->pool_holder()->external_name());
    return;
  }
}

void ClassVerifier::verify_cp_type(
    int bci, u2 index, const constantPoolHandle& cp, unsigned int types, TRAPS) {

  // In some situations, bytecode rewriting may occur while we're verifying.
  // In this case, a constant pool cache exists and some indices refer to that
  // instead.  Be sure we don't pick up such indices by accident.
  // We must check was_recursively_verified() before we get here.
  guarantee(cp->cache() == nullptr, "not rewritten yet");

  verify_cp_index(bci, cp, index, CHECK_VERIFY(this));
  unsigned int tag = cp->tag_at(index).value();
  // tags up to JVM_CONSTANT_ExternalMax are verifiable and valid for shift op
  if (tag > JVM_CONSTANT_ExternalMax || (types & (1 << tag)) == 0) {
    verify_error(ErrorContext::bad_cp_index(bci, index),
      "Illegal type at constant pool entry %d in class %s",
      index, cp->pool_holder()->external_name());
    return;
  }
}

void ClassVerifier::verify_cp_class_type(
    int bci, u2 index, const constantPoolHandle& cp, TRAPS) {
  verify_cp_index(bci, cp, index, CHECK_VERIFY(this));
  constantTag tag = cp->tag_at(index);
  if (!tag.is_klass() && !tag.is_unresolved_klass()) {
    verify_error(ErrorContext::bad_cp_index(bci, index),
        "Illegal type at constant pool entry %d in class %s",
        index, cp->pool_holder()->external_name());
    return;
  }
}

void ClassVerifier::verify_error(ErrorContext ctx, const char* msg, ...) {
  stringStream ss;

  ctx.reset_frames();
  _exception_type = vmSymbols::java_lang_VerifyError();
  _error_context = ctx;
  va_list va;
  va_start(va, msg);
  ss.vprint(msg, va);
  va_end(va);
  _message = ss.as_string();
#ifdef ASSERT
  ResourceMark rm;
  const char* exception_name = _exception_type->as_C_string();
  Exceptions::debug_check_abort(exception_name, nullptr);
#endif // ndef ASSERT
}

void ClassVerifier::class_format_error(const char* msg, ...) {
  stringStream ss;
  _exception_type = vmSymbols::java_lang_ClassFormatError();
  va_list va;
  va_start(va, msg);
  ss.vprint(msg, va);
  va_end(va);
  if (!_method.is_null()) {
    ss.print(" in method '");
    _method->print_external_name(&ss);
    ss.print("'");
  }
  _message = ss.as_string();
}

Klass* ClassVerifier::load_class(Symbol* name, TRAPS) {
  HandleMark hm(THREAD);
  // Get current loader first.
  oop loader = current_class()->class_loader();

  assert(name_in_supers(name, current_class()), "name should be a super class");

  Klass* kls = SystemDictionary::resolve_or_fail(
    name, Handle(THREAD, loader), true, THREAD);

  if (kls != nullptr) {
    if (log_is_enabled(Debug, class, resolve)) {
      Verifier::trace_class_resolution(kls, current_class());
    }
  }
  return kls;
}

bool ClassVerifier::is_protected_access(InstanceKlass* this_class,
                                        Klass* target_class,
                                        Symbol* field_name,
                                        Symbol* field_sig,
                                        bool is_method) {
  NoSafepointVerifier nosafepoint;

  // If target class isn't a super class of this class, we don't worry about this case
  if (!this_class->is_subclass_of(target_class)) {
    return false;
  }
  // Check if the specified method or field is protected
  InstanceKlass* target_instance = InstanceKlass::cast(target_class);
  fieldDescriptor fd;
  if (is_method) {
    Method* m = target_instance->uncached_lookup_method(field_name, field_sig, Klass::OverpassLookupMode::find);
    if (m != nullptr && m->is_protected()) {
      if (!this_class->is_same_class_package(m->method_holder())) {
        return true;
      }
    }
  } else {
    Klass* member_klass = target_instance->find_field(field_name, field_sig, &fd);
    if (member_klass != nullptr && fd.is_protected()) {
      if (!this_class->is_same_class_package(member_klass)) {
        return true;
      }
    }
  }
  return false;
}

void ClassVerifier::verify_ldc(
    int opcode, u2 index, StackMapFrame* current_frame,
    const constantPoolHandle& cp, int bci, TRAPS) {
  verify_cp_index(bci, cp, index, CHECK_VERIFY(this));
  constantTag tag = cp->tag_at(index);
  unsigned int types = 0;
  if (opcode == Bytecodes::_ldc || opcode == Bytecodes::_ldc_w) {
    if (!tag.is_unresolved_klass()) {
      types = (1 << JVM_CONSTANT_Integer) | (1 << JVM_CONSTANT_Float)
            | (1 << JVM_CONSTANT_String)  | (1 << JVM_CONSTANT_Class)
            | (1 << JVM_CONSTANT_MethodHandle) | (1 << JVM_CONSTANT_MethodType)
            | (1 << JVM_CONSTANT_Dynamic);
      // Note:  The class file parser already verified the legality of
      // MethodHandle and MethodType constants.
      verify_cp_type(bci, index, cp, types, CHECK_VERIFY(this));
    }
  } else {
    assert(opcode == Bytecodes::_ldc2_w, "must be ldc2_w");
    types = (1 << JVM_CONSTANT_Double) | (1 << JVM_CONSTANT_Long)
          | (1 << JVM_CONSTANT_Dynamic);
    verify_cp_type(bci, index, cp, types, CHECK_VERIFY(this));
  }
  if (tag.is_string()) {
    current_frame->push_stack(
      VerificationType::reference_type(
        vmSymbols::java_lang_String()), CHECK_VERIFY(this));
  } else if (tag.is_klass() || tag.is_unresolved_klass()) {
    current_frame->push_stack(
      VerificationType::reference_type(
        vmSymbols::java_lang_Class()), CHECK_VERIFY(this));
  } else if (tag.is_int()) {
    current_frame->push_stack(
      VerificationType::integer_type(), CHECK_VERIFY(this));
  } else if (tag.is_float()) {
    current_frame->push_stack(
      VerificationType::float_type(), CHECK_VERIFY(this));
  } else if (tag.is_double()) {
    current_frame->push_stack_2(
      VerificationType::double_type(),
      VerificationType::double2_type(), CHECK_VERIFY(this));
  } else if (tag.is_long()) {
    current_frame->push_stack_2(
      VerificationType::long_type(),
      VerificationType::long2_type(), CHECK_VERIFY(this));
  } else if (tag.is_method_handle()) {
    current_frame->push_stack(
      VerificationType::reference_type(
        vmSymbols::java_lang_invoke_MethodHandle()), CHECK_VERIFY(this));
  } else if (tag.is_method_type()) {
    current_frame->push_stack(
      VerificationType::reference_type(
        vmSymbols::java_lang_invoke_MethodType()), CHECK_VERIFY(this));
  } else if (tag.is_dynamic_constant()) {
    Symbol* constant_type = cp->uncached_signature_ref_at(index);
    // Field signature was checked in ClassFileParser.
    assert(SignatureVerifier::is_valid_type_signature(constant_type),
           "Invalid type for dynamic constant");
    assert(sizeof(VerificationType) == sizeof(uintptr_t),
          "buffer type must match VerificationType size");
    uintptr_t constant_type_buffer[2];
    VerificationType* v_constant_type = (VerificationType*)constant_type_buffer;
    SignatureStream sig_stream(constant_type, false);
    int n = change_sig_to_verificationType(&sig_stream, v_constant_type);
    int opcode_n = (opcode == Bytecodes::_ldc2_w ? 2 : 1);
    if (n != opcode_n) {
      // wrong kind of ldc; reverify against updated type mask
      types &= ~(1 << JVM_CONSTANT_Dynamic);
      verify_cp_type(bci, index, cp, types, CHECK_VERIFY(this));
    }
    for (int i = 0; i < n; i++) {
      current_frame->push_stack(v_constant_type[i], CHECK_VERIFY(this));
    }
  } else {
    /* Unreachable? verify_cp_type has already validated the cp type. */
    verify_error(
        ErrorContext::bad_cp_index(bci, index), "Invalid index in ldc");
    return;
  }
}

void ClassVerifier::verify_switch(
    RawBytecodeStream* bcs, u4 code_length, char* code_data,
    StackMapFrame* current_frame, StackMapTable* stackmap_table, TRAPS) {
  int bci = bcs->bci();
  address bcp = bcs->bcp();
  address aligned_bcp = align_up(bcp + 1, jintSize);

  if (_klass->major_version() < NONZERO_PADDING_BYTES_IN_SWITCH_MAJOR_VERSION) {
    // 4639449 & 4647081: padding bytes must be 0
    u2 padding_offset = 1;
    while ((bcp + padding_offset) < aligned_bcp) {
      if(*(bcp + padding_offset) != 0) {
        verify_error(ErrorContext::bad_code(bci),
                     "Nonzero padding byte in lookupswitch or tableswitch");
        return;
      }
      padding_offset++;
    }
  }

  int default_offset = (int) Bytes::get_Java_u4(aligned_bcp);
  int keys, delta;
  current_frame->pop_stack(
    VerificationType::integer_type(), CHECK_VERIFY(this));
  if (bcs->raw_code() == Bytecodes::_tableswitch) {
    jint low = (jint)Bytes::get_Java_u4(aligned_bcp + jintSize);
    jint high = (jint)Bytes::get_Java_u4(aligned_bcp + 2*jintSize);
    if (low > high) {
      verify_error(ErrorContext::bad_code(bci),
          "low must be less than or equal to high in tableswitch");
      return;
    }
    int64_t keys64 = ((int64_t)high - low) + 1;
    if (keys64 > 65535) {  // Max code length
      verify_error(ErrorContext::bad_code(bci), "too many keys in tableswitch");
      return;
    }
    keys = (int)keys64;
    delta = 1;
  } else {
    keys = (int)Bytes::get_Java_u4(aligned_bcp + jintSize);
    if (keys < 0) {
      verify_error(ErrorContext::bad_code(bci),
                   "number of keys in lookupswitch less than 0");
      return;
    }
    delta = 2;
    // Make sure that the lookupswitch items are sorted
    for (int i = 0; i < (keys - 1); i++) {
      jint this_key = Bytes::get_Java_u4(aligned_bcp + (2+2*i)*jintSize);
      jint next_key = Bytes::get_Java_u4(aligned_bcp + (2+2*i+2)*jintSize);
      if (this_key >= next_key) {
        verify_error(ErrorContext::bad_code(bci),
                     "Bad lookupswitch instruction");
        return;
      }
    }
  }
  stackmap_table->check_jump_target(current_frame, bci, default_offset, CHECK_VERIFY(this));
  for (int i = 0; i < keys; i++) {
    // Because check_jump_target() may safepoint, the bytecode could have
    // moved, which means 'aligned_bcp' is no good and needs to be recalculated.
    aligned_bcp = align_up(bcs->bcp() + 1, jintSize);
    int offset = (jint)Bytes::get_Java_u4(aligned_bcp+(3+i*delta)*jintSize);
    stackmap_table->check_jump_target(
      current_frame, bci, offset, CHECK_VERIFY(this));
  }
  NOT_PRODUCT(aligned_bcp = nullptr);  // no longer valid at this point
}

bool ClassVerifier::name_in_supers(
    Symbol* ref_name, InstanceKlass* current) {
  Klass* super = current->super();
  while (super != nullptr) {
    if (super->name() == ref_name) {
      return true;
    }
    super = super->super();
  }
  return false;
}

void ClassVerifier::verify_field_instructions(RawBytecodeStream* bcs,
                                              StackMapFrame* current_frame,
                                              const constantPoolHandle& cp,
                                              bool allow_arrays,
                                              TRAPS) {
  u2 index = bcs->get_index_u2();
  verify_cp_type(bcs->bci(), index, cp,
      1 << JVM_CONSTANT_Fieldref, CHECK_VERIFY(this));

  // Get field name and signature
  Symbol* field_name = cp->uncached_name_ref_at(index);
  Symbol* field_sig = cp->uncached_signature_ref_at(index);
  bool is_getfield = false;

  // Field signature was checked in ClassFileParser.
  assert(SignatureVerifier::is_valid_type_signature(field_sig),
         "Invalid field signature");

  // Get referenced class type
  VerificationType ref_class_type = cp_ref_index_to_type(
    index, cp, CHECK_VERIFY(this));
  if (!ref_class_type.is_object() &&
    (!allow_arrays || !ref_class_type.is_array())) {
    verify_error(ErrorContext::bad_type(bcs->bci(),
        TypeOrigin::cp(index, ref_class_type)),
        "Expecting reference to class in class %s at constant pool index %d",
        _klass->external_name(), index);
    return;
  }
  VerificationType target_class_type = ref_class_type;

  assert(sizeof(VerificationType) == sizeof(uintptr_t),
        "buffer type must match VerificationType size");
  uintptr_t field_type_buffer[2];
  VerificationType* field_type = (VerificationType*)field_type_buffer;
  // If we make a VerificationType[2] array directly, the compiler calls
  // to the c-runtime library to do the allocation instead of just
  // stack allocating it.  Plus it would run constructors.  This shows up
  // in performance profiles.

  SignatureStream sig_stream(field_sig, false);
  VerificationType stack_object_type;
  int n = change_sig_to_verificationType(&sig_stream, field_type);
  int bci = bcs->bci();
  bool is_assignable;
  switch (bcs->raw_code()) {
    case Bytecodes::_getstatic: {
      for (int i = 0; i < n; i++) {
        current_frame->push_stack(field_type[i], CHECK_VERIFY(this));
      }
      break;
    }
    case Bytecodes::_putstatic: {
      for (int i = n - 1; i >= 0; i--) {
        current_frame->pop_stack(field_type[i], CHECK_VERIFY(this));
      }
      break;
    }
    case Bytecodes::_getfield: {
      is_getfield = true;
      stack_object_type = current_frame->pop_stack(
        target_class_type, CHECK_VERIFY(this));
      goto check_protected;
    }
    case Bytecodes::_putfield: {
      for (int i = n - 1; i >= 0; i--) {
        current_frame->pop_stack(field_type[i], CHECK_VERIFY(this));
      }
      stack_object_type = current_frame->pop_stack(CHECK_VERIFY(this));

      // The JVMS 2nd edition allows field initialization before the superclass
      // initializer, if the field is defined within the current class.
      fieldDescriptor fd;
      if (stack_object_type == VerificationType::uninitialized_this_type() &&
          target_class_type.equals(current_type()) &&
          _klass->find_local_field(field_name, field_sig, &fd)) {
        stack_object_type = current_type();
      }
      is_assignable = target_class_type.is_assignable_from(
        stack_object_type, this, false, CHECK_VERIFY(this));
      if (!is_assignable) {
        verify_error(ErrorContext::bad_type(bci,
            current_frame->stack_top_ctx(),
            TypeOrigin::cp(index, target_class_type)),
            "Bad type on operand stack in putfield");
        return;
      }
    }
    check_protected: {
      if (_this_type == stack_object_type)
        break; // stack_object_type must be assignable to _current_class_type
      if (was_recursively_verified()) {
        if (is_getfield) {
          // Push field type for getfield.
          for (int i = 0; i < n; i++) {
            current_frame->push_stack(field_type[i], CHECK_VERIFY(this));
          }
        }
        return;
      }
      Symbol* ref_class_name =
        cp->klass_name_at(cp->uncached_klass_ref_index_at(index));
      if (!name_in_supers(ref_class_name, current_class()))
        // stack_object_type must be assignable to _current_class_type since:
        // 1. stack_object_type must be assignable to ref_class.
        // 2. ref_class must be _current_class or a subclass of it. It can't
        //    be a superclass of it. See revised JVMS 5.4.4.
        break;

      Klass* ref_class_oop = load_class(ref_class_name, CHECK);
      if (is_protected_access(current_class(), ref_class_oop, field_name,
                              field_sig, false)) {
        // It's protected access, check if stack object is assignable to
        // current class.
        is_assignable = current_type().is_assignable_from(
          stack_object_type, this, true, CHECK_VERIFY(this));
        if (!is_assignable) {
          verify_error(ErrorContext::bad_type(bci,
              current_frame->stack_top_ctx(),
              TypeOrigin::implicit(current_type())),
              "Bad access to protected data in %s",
              is_getfield ? "getfield" : "putfield");
          return;
        }
      }
      break;
    }
    default: ShouldNotReachHere();
  }
  if (is_getfield) {
    // Push field type for getfield after doing protection check.
    for (int i = 0; i < n; i++) {
      current_frame->push_stack(field_type[i], CHECK_VERIFY(this));
    }
  }
}

void ClassVerifier::verify_invoke_init(
    RawBytecodeStream* bcs, u2 ref_class_index, VerificationType ref_class_type,
    StackMapFrame* current_frame, u4 code_length, bool in_try_block,
    bool *this_uninit, const constantPoolHandle& cp, StackMapTable* stackmap_table,
    TRAPS) {
  int bci = bcs->bci();
  VerificationType type = current_frame->pop_stack(
    VerificationType::reference_check(), CHECK_VERIFY(this));
  if (type == VerificationType::uninitialized_this_type()) {
    // The method must be an <init> method of this class or its superclass
    Klass* superk = current_class()->super();
    if (ref_class_type.name() != current_class()->name() &&
        ref_class_type.name() != superk->name()) {
      verify_error(ErrorContext::bad_type(bci,
          TypeOrigin::implicit(ref_class_type),
          TypeOrigin::implicit(current_type())),
          "Bad <init> method call");
      return;
    }

    // If this invokespecial call is done from inside of a TRY block then make
    // sure that all catch clause paths end in a throw.  Otherwise, this can
    // result in returning an incomplete object.
    if (in_try_block) {
      // Check the exception handler target stackmaps with the locals from the
      // incoming stackmap (before initialize_object() changes them to outgoing
      // state).
      if (was_recursively_verified()) return;
      verify_exception_handler_targets(bci, true, current_frame,
                                       stackmap_table, CHECK_VERIFY(this));
    } // in_try_block

    current_frame->initialize_object(type, current_type());
    *this_uninit = true;
  } else if (type.is_uninitialized()) {
    u2 new_offset = type.bci();
    address new_bcp = bcs->bcp() - bci + new_offset;
    if (new_offset > (code_length - 3) || (*new_bcp) != Bytecodes::_new) {
      /* Unreachable?  Stack map parsing ensures valid type and new
       * instructions have a valid BCI. */
      verify_error(ErrorContext::bad_code(new_offset),
                   "Expecting new instruction");
      return;
    }
    u2 new_class_index = Bytes::get_Java_u2(new_bcp + 1);
    if (was_recursively_verified()) return;
    verify_cp_class_type(bci, new_class_index, cp, CHECK_VERIFY(this));

    // The method must be an <init> method of the indicated class
    VerificationType new_class_type = cp_index_to_type(
      new_class_index, cp, CHECK_VERIFY(this));
    if (!new_class_type.equals(ref_class_type)) {
      verify_error(ErrorContext::bad_type(bci,
          TypeOrigin::cp(new_class_index, new_class_type),
          TypeOrigin::cp(ref_class_index, ref_class_type)),
          "Call to wrong <init> method");
      return;
    }
    // According to the VM spec, if the referent class is a superclass of the
    // current class, and is in a different runtime package, and the method is
    // protected, then the objectref must be the current class or a subclass
    // of the current class.
    VerificationType objectref_type = new_class_type;
    if (name_in_supers(ref_class_type.name(), current_class())) {
      Klass* ref_klass = load_class(ref_class_type.name(), CHECK);
      if (was_recursively_verified()) return;
      Method* m = InstanceKlass::cast(ref_klass)->uncached_lookup_method(
        vmSymbols::object_initializer_name(),
        cp->uncached_signature_ref_at(bcs->get_index_u2()),
        Klass::OverpassLookupMode::find);
      // Do nothing if method is not found.  Let resolution detect the error.
      if (m != nullptr) {
        InstanceKlass* mh = m->method_holder();
        if (m->is_protected() && !mh->is_same_class_package(_klass)) {
          bool assignable = current_type().is_assignable_from(
            objectref_type, this, true, CHECK_VERIFY(this));
          if (!assignable) {
            verify_error(ErrorContext::bad_type(bci,
                TypeOrigin::cp(new_class_index, objectref_type),
                TypeOrigin::implicit(current_type())),
                "Bad access to protected <init> method");
            return;
          }
        }
      }
    }
    // Check the exception handler target stackmaps with the locals from the
    // incoming stackmap (before initialize_object() changes them to outgoing
    // state).
    if (in_try_block) {
      if (was_recursively_verified()) return;
      verify_exception_handler_targets(bci, *this_uninit, current_frame,
                                       stackmap_table, CHECK_VERIFY(this));
    }
    current_frame->initialize_object(type, new_class_type);
  } else {
    verify_error(ErrorContext::bad_type(bci, current_frame->stack_top_ctx()),
        "Bad operand type when invoking <init>");
    return;
  }
}

bool ClassVerifier::is_same_or_direct_interface(
    InstanceKlass* klass,
    VerificationType klass_type,
    VerificationType ref_class_type) {
  if (ref_class_type.equals(klass_type)) return true;
  Array<InstanceKlass*>* local_interfaces = klass->local_interfaces();
  if (local_interfaces != nullptr) {
    for (int x = 0; x < local_interfaces->length(); x++) {
      InstanceKlass* k = local_interfaces->at(x);
      assert (k != nullptr && k->is_interface(), "invalid interface");
      if (ref_class_type.equals(VerificationType::reference_type(k->name()))) {
        return true;
      }
    }
  }
  return false;
}

void ClassVerifier::verify_invoke_instructions(
    RawBytecodeStream* bcs, u4 code_length, StackMapFrame* current_frame,
    bool in_try_block, bool *this_uninit, VerificationType return_type,
    const constantPoolHandle& cp, StackMapTable* stackmap_table, TRAPS) {
  // Make sure the constant pool item is the right type
  u2 index = bcs->get_index_u2();
  Bytecodes::Code opcode = bcs->raw_code();
  unsigned int types = 0;
  switch (opcode) {
    case Bytecodes::_invokeinterface:
      types = 1 << JVM_CONSTANT_InterfaceMethodref;
      break;
    case Bytecodes::_invokedynamic:
      types = 1 << JVM_CONSTANT_InvokeDynamic;
      break;
    case Bytecodes::_invokespecial:
    case Bytecodes::_invokestatic:
      types = (_klass->major_version() < STATIC_METHOD_IN_INTERFACE_MAJOR_VERSION) ?
        (1 << JVM_CONSTANT_Methodref) :
        ((1 << JVM_CONSTANT_InterfaceMethodref) | (1 << JVM_CONSTANT_Methodref));
      break;
    default:
      types = 1 << JVM_CONSTANT_Methodref;
  }
  verify_cp_type(bcs->bci(), index, cp, types, CHECK_VERIFY(this));

  // Get method name and signature
  Symbol* method_name = cp->uncached_name_ref_at(index);
  Symbol* method_sig = cp->uncached_signature_ref_at(index);

  // Method signature was checked in ClassFileParser.
  assert(SignatureVerifier::is_valid_method_signature(method_sig),
         "Invalid method signature");

  // Get referenced class type
  VerificationType ref_class_type;
  if (opcode == Bytecodes::_invokedynamic) {
    if (_klass->major_version() < Verifier::INVOKEDYNAMIC_MAJOR_VERSION) {
      class_format_error(
        "invokedynamic instructions not supported by this class file version (%d), class %s",
        _klass->major_version(), _klass->external_name());
      return;
    }
  } else {
    ref_class_type = cp_ref_index_to_type(index, cp, CHECK_VERIFY(this));
  }

  assert(sizeof(VerificationType) == sizeof(uintptr_t),
        "buffer type must match VerificationType size");

  // Get the UTF8 index for this signature.
  int sig_index = cp->signature_ref_index_at(cp->uncached_name_and_type_ref_index_at(index));

  // Get the signature's verification types.
  sig_as_verification_types* mth_sig_verif_types;
  sig_as_verification_types** mth_sig_verif_types_ptr = method_signatures_table()->get(sig_index);
  if (mth_sig_verif_types_ptr != nullptr) {
    // Found the entry for the signature's verification types in the hash table.
    mth_sig_verif_types = *mth_sig_verif_types_ptr;
    assert(mth_sig_verif_types != nullptr, "Unexpected null sig_as_verification_types value");
  } else {
    // Not found, add the entry to the table.
    GrowableArray<VerificationType>* verif_types = new GrowableArray<VerificationType>(10);
    mth_sig_verif_types = new sig_as_verification_types(verif_types);
    create_method_sig_entry(mth_sig_verif_types, sig_index);
  }

  // Get the number of arguments for this signature.
  int nargs = mth_sig_verif_types->num_args();

  // Check instruction operands
  int bci = bcs->bci();
  if (opcode == Bytecodes::_invokeinterface) {
    address bcp = bcs->bcp();
    // 4905268: count operand in invokeinterface should be nargs+1, not nargs.
    // JSR202 spec: The count operand of an invokeinterface instruction is valid if it is
    // the difference between the size of the operand stack before and after the instruction
    // executes.
    if (*(bcp+3) != (nargs+1)) {
      verify_error(ErrorContext::bad_code(bci),
          "Inconsistent args count operand in invokeinterface");
      return;
    }
    if (*(bcp+4) != 0) {
      verify_error(ErrorContext::bad_code(bci),
          "Fourth operand byte of invokeinterface must be zero");
      return;
    }
  }

  if (opcode == Bytecodes::_invokedynamic) {
    address bcp = bcs->bcp();
    if (*(bcp+3) != 0 || *(bcp+4) != 0) {
      verify_error(ErrorContext::bad_code(bci),
          "Third and fourth operand bytes of invokedynamic must be zero");
      return;
    }
  }

  if (method_name->char_at(0) == JVM_SIGNATURE_SPECIAL) {
    // Make sure <init> can only be invoked by invokespecial
    if (opcode != Bytecodes::_invokespecial ||
        method_name != vmSymbols::object_initializer_name()) {
      verify_error(ErrorContext::bad_code(bci),
          "Illegal call to internal method");
      return;
    }
  }
  // invokespecial, when not <init>, must be to a method in the current class, a direct superinterface,
  // or any superclass (including Object).
  else if (opcode == Bytecodes::_invokespecial
           && !is_same_or_direct_interface(current_class(), current_type(), ref_class_type)
           && !ref_class_type.equals(VerificationType::reference_type(current_class()->super()->name()))) {

    // We know it is not current class, direct superinterface or immediate superclass. That means it
    // could be:
    // - a totally unrelated class or interface
    // - an indirect superinterface
    // - an indirect superclass (including Object)
    // We use the assignability test to see if it is a superclass, or else an interface, and keep track
    // of the latter. Note that subtype can be true if we are dealing with an interface that is not actually
    // implemented as assignability treats all interfaces as Object.

    bool is_interface = false; // This can only be set true if the assignability check will return true
                               // and we loaded the class. For any other "true" returns (e.g. same class
                               // or Object) we either can't get here (same class already excluded above)
                               // or we know it is not an interface (i.e. Object).
    bool subtype = ref_class_type.is_reference_assignable_from(current_type(), this, false,
                                                               &is_interface, CHECK_VERIFY(this));
    if (!subtype) {  // Totally unrelated class
      verify_error(ErrorContext::bad_code(bci),
                   "Bad invokespecial instruction: "
                   "current class isn't assignable to reference class.");
      return;
    } else {
      // Indirect superclass (including Object), indirect interface, or unrelated interface.
      // Any interface use is an error.
      if (is_interface) {
        verify_error(ErrorContext::bad_code(bci),
                     "Bad invokespecial instruction: "
                     "interface method to invoke is not in a direct superinterface.");
        return;
      }
    }
  }

  // Get the verification types for the method's arguments.
  GrowableArray<VerificationType>* sig_verif_types = mth_sig_verif_types->sig_verif_types();
  assert(sig_verif_types != nullptr, "Missing signature's array of verification types");
  // Match method descriptor with operand stack
  // The arguments are on the stack in descending order.
  for (int i = nargs - 1; i >= 0; i--) { // Run backwards
    current_frame->pop_stack(sig_verif_types->at(i), CHECK_VERIFY(this));
  }

  // Check objectref on operand stack
  if (opcode != Bytecodes::_invokestatic &&
      opcode != Bytecodes::_invokedynamic) {
    if (method_name == vmSymbols::object_initializer_name()) {  // <init> method
      verify_invoke_init(bcs, index, ref_class_type, current_frame,
        code_length, in_try_block, this_uninit, cp, stackmap_table,
        CHECK_VERIFY(this));
      if (was_recursively_verified()) return;
    } else {   // other methods
      // Ensures that target class is assignable to method class.
      if (opcode == Bytecodes::_invokespecial) {
        current_frame->pop_stack(current_type(), CHECK_VERIFY(this));
      } else if (opcode == Bytecodes::_invokevirtual) {
        VerificationType stack_object_type =
          current_frame->pop_stack(ref_class_type, CHECK_VERIFY(this));
        if (current_type() != stack_object_type) {
          if (was_recursively_verified()) return;
          assert(cp->cache() == nullptr, "not rewritten yet");
          Symbol* ref_class_name =
            cp->klass_name_at(cp->uncached_klass_ref_index_at(index));
          // See the comments in verify_field_instructions() for
          // the rationale behind this.
          if (name_in_supers(ref_class_name, current_class())) {
            Klass* ref_class = load_class(ref_class_name, CHECK);
            if (is_protected_access(
                  _klass, ref_class, method_name, method_sig, true)) {
              // It's protected access, check if stack object is
              // assignable to current class.
              if (ref_class_type.name() == vmSymbols::java_lang_Object()
                  && stack_object_type.is_array()
                  && method_name == vmSymbols::clone_name()) {
                // Special case: arrays pretend to implement public Object
                // clone().
              } else {
                bool is_assignable = current_type().is_assignable_from(
                  stack_object_type, this, true, CHECK_VERIFY(this));
                if (!is_assignable) {
                  verify_error(ErrorContext::bad_type(bci,
                      current_frame->stack_top_ctx(),
                      TypeOrigin::implicit(current_type())),
                      "Bad access to protected data in invokevirtual");
                  return;
                }
              }
            }
          }
        }
      } else {
        assert(opcode == Bytecodes::_invokeinterface, "Unexpected opcode encountered");
        current_frame->pop_stack(ref_class_type, CHECK_VERIFY(this));
      }
    }
  }
  // Push the result type.
  int sig_verif_types_len = sig_verif_types->length();
  if (sig_verif_types_len > nargs) {  // There's a return type
    if (method_name == vmSymbols::object_initializer_name()) {
      // <init> method must have a void return type
      /* Unreachable?  Class file parser verifies that methods with '<' have
       * void return */
      verify_error(ErrorContext::bad_code(bci),
          "Return type must be void in <init> method");
      return;
    }

    assert(sig_verif_types_len <= nargs + 2,
           "Signature verification types array return type is bogus");
    for (int i = nargs; i < sig_verif_types_len; i++) {
      assert(i == nargs || sig_verif_types->at(i).is_long2() ||
             sig_verif_types->at(i).is_double2(), "Unexpected return verificationType");
      current_frame->push_stack(sig_verif_types->at(i), CHECK_VERIFY(this));
    }
  }
}

VerificationType ClassVerifier::get_newarray_type(
    u2 index, int bci, TRAPS) {
  const char* from_bt[] = {
    nullptr, nullptr, nullptr, nullptr, "[Z", "[C", "[F", "[D", "[B", "[S", "[I", "[J",
  };
  if (index < T_BOOLEAN || index > T_LONG) {
    verify_error(ErrorContext::bad_code(bci), "Illegal newarray instruction");
    return VerificationType::bogus_type();
  }

  // from_bt[index] contains the array signature which has a length of 2
  Symbol* sig = create_temporary_symbol(from_bt[index], 2);
  return VerificationType::reference_type(sig);
}

void ClassVerifier::verify_anewarray(
    int bci, u2 index, const constantPoolHandle& cp,
    StackMapFrame* current_frame, TRAPS) {
  verify_cp_class_type(bci, index, cp, CHECK_VERIFY(this));
  current_frame->pop_stack(
    VerificationType::integer_type(), CHECK_VERIFY(this));

  if (was_recursively_verified()) return;
  VerificationType component_type =
    cp_index_to_type(index, cp, CHECK_VERIFY(this));
  int length;
  char* arr_sig_str;
  if (component_type.is_array()) {     // it's an array
    const char* component_name = component_type.name()->as_utf8();
    // Check for more than MAX_ARRAY_DIMENSIONS
    length = (int)strlen(component_name);
    if (length > MAX_ARRAY_DIMENSIONS &&
        component_name[MAX_ARRAY_DIMENSIONS - 1] == JVM_SIGNATURE_ARRAY) {
      verify_error(ErrorContext::bad_code(bci),
        "Illegal anewarray instruction, array has more than 255 dimensions");
    }
    // add one dimension to component
    length++;
    arr_sig_str = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, length + 1);
    int n = os::snprintf(arr_sig_str, length + 1, "%c%s",
                         JVM_SIGNATURE_ARRAY, component_name);
    assert(n == length, "Unexpected number of characters in string");
  } else {         // it's an object or interface
    const char* component_name = component_type.name()->as_utf8();
    // add one dimension to component with 'L' prepended and ';' postpended.
    length = (int)strlen(component_name) + 3;
    arr_sig_str = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, length + 1);
    int n = os::snprintf(arr_sig_str, length + 1, "%c%c%s;",
                         JVM_SIGNATURE_ARRAY, JVM_SIGNATURE_CLASS, component_name);
    assert(n == length, "Unexpected number of characters in string");
  }
  Symbol* arr_sig = create_temporary_symbol(arr_sig_str, length);
  VerificationType new_array_type = VerificationType::reference_type(arr_sig);
  current_frame->push_stack(new_array_type, CHECK_VERIFY(this));
}

void ClassVerifier::verify_iload(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->get_local(
    index, VerificationType::integer_type(), CHECK_VERIFY(this));
  current_frame->push_stack(
    VerificationType::integer_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_lload(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->get_local_2(
    index, VerificationType::long_type(),
    VerificationType::long2_type(), CHECK_VERIFY(this));
  current_frame->push_stack_2(
    VerificationType::long_type(),
    VerificationType::long2_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_fload(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->get_local(
    index, VerificationType::float_type(), CHECK_VERIFY(this));
  current_frame->push_stack(
    VerificationType::float_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_dload(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->get_local_2(
    index, VerificationType::double_type(),
    VerificationType::double2_type(), CHECK_VERIFY(this));
  current_frame->push_stack_2(
    VerificationType::double_type(),
    VerificationType::double2_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_aload(int index, StackMapFrame* current_frame, TRAPS) {
  VerificationType type = current_frame->get_local(
    index, VerificationType::reference_check(), CHECK_VERIFY(this));
  current_frame->push_stack(type, CHECK_VERIFY(this));
}

void ClassVerifier::verify_istore(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->pop_stack(
    VerificationType::integer_type(), CHECK_VERIFY(this));
  current_frame->set_local(
    index, VerificationType::integer_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_lstore(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->pop_stack_2(
    VerificationType::long2_type(),
    VerificationType::long_type(), CHECK_VERIFY(this));
  current_frame->set_local_2(
    index, VerificationType::long_type(),
    VerificationType::long2_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_fstore(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->pop_stack(VerificationType::float_type(), CHECK_VERIFY(this));
  current_frame->set_local(
    index, VerificationType::float_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_dstore(int index, StackMapFrame* current_frame, TRAPS) {
  current_frame->pop_stack_2(
    VerificationType::double2_type(),
    VerificationType::double_type(), CHECK_VERIFY(this));
  current_frame->set_local_2(
    index, VerificationType::double_type(),
    VerificationType::double2_type(), CHECK_VERIFY(this));
}

void ClassVerifier::verify_astore(int index, StackMapFrame* current_frame, TRAPS) {
  VerificationType type = current_frame->pop_stack(
    VerificationType::reference_check(), CHECK_VERIFY(this));
  current_frame->set_local(index, type, CHECK_VERIFY(this));
}

void ClassVerifier::verify_iinc(int index, StackMapFrame* current_frame, TRAPS) {
  VerificationType type = current_frame->get_local(
    index, VerificationType::integer_type(), CHECK_VERIFY(this));
  current_frame->set_local(index, type, CHECK_VERIFY(this));
}

void ClassVerifier::verify_return_value(
    VerificationType return_type, VerificationType type, int bci,
    StackMapFrame* current_frame, TRAPS) {
  if (return_type == VerificationType::bogus_type()) {
    verify_error(ErrorContext::bad_type(bci,
        current_frame->stack_top_ctx(), TypeOrigin::signature(return_type)),
        "Method does not expect a return value");
    return;
  }
  bool match = return_type.is_assignable_from(type, this, false, CHECK_VERIFY(this));
  if (!match) {
    verify_error(ErrorContext::bad_type(bci,
        current_frame->stack_top_ctx(), TypeOrigin::signature(return_type)),
        "Bad return type");
    return;
  }
}

// The verifier creates symbols which are substrings of Symbols.
// These are stored in the verifier until the end of verification so that
// they can be reference counted.
Symbol* ClassVerifier::create_temporary_symbol(const char *name, int length) {
  // Quick deduplication check
  if (_previous_symbol != nullptr && _previous_symbol->equals(name, length)) {
    return _previous_symbol;
  }
  Symbol* sym = SymbolTable::new_symbol(name, length);
  if (!sym->is_permanent()) {
    if (_symbols == nullptr) {
      _symbols = new GrowableArray<Symbol*>(50, 0, nullptr);
    }
    _symbols->push(sym);
  }
  _previous_symbol = sym;
  return sym;
}