xref: /art/runtime/verifier/method_verifier.cc

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "method_verifier-inl.h"

#include <ostream>

#include "android-base/stringprintf.h"

#include "art_field-inl.h"
#include "art_method-inl.h"
#include "base/aborting.h"
#include "base/leb128.h"
#include "base/indenter.h"
#include "base/logging.h"  // For VLOG.
#include "base/mutex-inl.h"
#include "base/pointer_size.h"
#include "base/sdk_version.h"
#include "base/stl_util.h"
#include "base/systrace.h"
#include "base/time_utils.h"
#include "base/utils.h"
#include "class_linker.h"
#include "class_root-inl.h"
#include "dex/class_accessor-inl.h"
#include "dex/descriptors_names.h"
#include "dex/dex_file-inl.h"
#include "dex/dex_file_exception_helpers.h"
#include "dex/dex_instruction-inl.h"
#include "dex/dex_instruction_utils.h"
#include "experimental_flags.h"
#include "gc/accounting/card_table-inl.h"
#include "handle_scope-inl.h"
#include "intern_table.h"
#include "mirror/class-inl.h"
#include "mirror/class.h"
#include "mirror/class_loader.h"
#include "mirror/dex_cache-inl.h"
#include "mirror/method_handle_impl.h"
#include "mirror/method_type.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "mirror/var_handle.h"
#include "obj_ptr-inl.h"
#include "reg_type-inl.h"
#include "register_line-inl.h"
#include "runtime.h"
#include "scoped_newline.h"
#include "scoped_thread_state_change-inl.h"
#include "stack.h"
#include "vdex_file.h"
#include "verifier/method_verifier.h"
#include "verifier_deps.h"

namespace art HIDDEN {
namespace verifier {

using android::base::StringPrintf;

static constexpr bool kTimeVerifyMethod = !kIsDebugBuild;

PcToRegisterLineTable::PcToRegisterLineTable(ScopedArenaAllocator& allocator)
    : register_lines_(allocator.Adapter(kArenaAllocVerifier)) {}

void PcToRegisterLineTable::Init(InstructionFlags* flags,
                                 uint32_t insns_size,
                                 uint16_t registers_size,
                                 ScopedArenaAllocator& allocator,
                                 RegTypeCache* reg_types,
                                 uint32_t interesting_dex_pc) {
  DCHECK_GT(insns_size, 0U);
  register_lines_.resize(insns_size);
  for (uint32_t i = 0; i < insns_size; i++) {
    if ((i == interesting_dex_pc) || flags[i].IsBranchTarget()) {
      register_lines_[i].reset(RegisterLine::Create(registers_size, allocator, reg_types));
    }
  }
}

PcToRegisterLineTable::~PcToRegisterLineTable() {}

namespace impl {
namespace {

enum class CheckAccess {
  kNo,
  kOnResolvedClass,
  kYes,
};

enum class FieldAccessType {
  kAccGet,
  kAccPut
};

// Instruction types that are not marked as throwing (because they normally would not), but for
// historical reasons may do so. These instructions cannot be marked kThrow as that would introduce
// a general flow that is unwanted.
//
// Note: Not implemented as Instruction::Flags value as that set is full and we'd need to increase
//       the struct size (making it a non-power-of-two) for a single element.
//
// Note: This should eventually be removed.
constexpr bool IsCompatThrow(Instruction::Code opcode) {
  return opcode == Instruction::Code::RETURN_OBJECT || opcode == Instruction::Code::MOVE_EXCEPTION;
}

template <bool kVerifierDebug>
class MethodVerifier final : public ::art::verifier::MethodVerifier {
 public:
  bool IsInstanceConstructor() const {
    return IsConstructor() && !IsStatic();
  }

  const RegType& ResolveCheckedClass(dex::TypeIndex class_idx) override
      REQUIRES_SHARED(Locks::mutator_lock_) {
    DCHECK(!HasFailures());
    const RegType& result = ResolveClass<CheckAccess::kYes>(class_idx);
    DCHECK(!HasFailures());
    return result;
  }

  void FindLocksAtDexPc() REQUIRES_SHARED(Locks::mutator_lock_);

 private:
  MethodVerifier(Thread* self,
                 ClassLinker* class_linker,
                 ArenaPool* arena_pool,
                 VerifierDeps* verifier_deps,
                 const DexFile* dex_file,
                 const dex::CodeItem* code_item,
                 uint32_t method_idx,
                 bool can_load_classes,
                 bool allow_thread_suspension,
                 bool aot_mode,
                 Handle<mirror::DexCache> dex_cache,
                 Handle<mirror::ClassLoader> class_loader,
                 const dex::ClassDef& class_def,
                 uint32_t access_flags,
                 bool verify_to_dump,
                 uint32_t api_level) REQUIRES_SHARED(Locks::mutator_lock_)
     : art::verifier::MethodVerifier(self,
                                     class_linker,
                                     arena_pool,
                                     verifier_deps,
                                     dex_file,
                                     class_def,
                                     code_item,
                                     method_idx,
                                     can_load_classes,
                                     allow_thread_suspension,
                                     aot_mode),
       method_access_flags_(access_flags),
       return_type_(nullptr),
       dex_cache_(dex_cache),
       class_loader_(class_loader),
       declaring_class_(nullptr),
       interesting_dex_pc_(-1),
       monitor_enter_dex_pcs_(nullptr),
       verify_to_dump_(verify_to_dump),
       allow_thread_suspension_(allow_thread_suspension),
       is_constructor_(false),
       api_level_(api_level == 0 ? std::numeric_limits<uint32_t>::max() : api_level) {
  }

  void UninstantiableError(const char* descriptor) {
    Fail(VerifyError::VERIFY_ERROR_NO_CLASS) << "Could not create precise reference for "
                                             << "non-instantiable klass " << descriptor;
  }
  static bool IsInstantiableOrPrimitive(ObjPtr<mirror::Class> klass)
      REQUIRES_SHARED(Locks::mutator_lock_) {
    return klass->IsInstantiable() || klass->IsPrimitive();
  }

  // Is the method being verified a constructor? See the comment on the field.
  bool IsConstructor() const {
    return is_constructor_;
  }

  // Is the method verified static?
  bool IsStatic() const {
    return (method_access_flags_ & kAccStatic) != 0;
  }

  // Adds the given string to the beginning of the last failure message.
  void PrependToLastFailMessage(std::string prepend) {
    size_t failure_num = failure_messages_.size();
    DCHECK_NE(failure_num, 0U);
    std::ostringstream* last_fail_message = failure_messages_[failure_num - 1];
    prepend += last_fail_message->str();
    failure_messages_[failure_num - 1] = new std::ostringstream(prepend, std::ostringstream::ate);
    delete last_fail_message;
  }

  // Adds the given string to the end of the last failure message.
  void AppendToLastFailMessage(const std::string& append) {
    size_t failure_num = failure_messages_.size();
    DCHECK_NE(failure_num, 0U);
    std::ostringstream* last_fail_message = failure_messages_[failure_num - 1];
    (*last_fail_message) << append;
  }

  /*
   * Compute the width of the instruction at each address in the instruction stream, and store it in
   * insn_flags_. Addresses that are in the middle of an instruction, or that are part of switch
   * table data, are not touched (so the caller should probably initialize "insn_flags" to zero).
   *
   * The "new_instance_count_" and "monitor_enter_count_" fields in vdata are also set.
   *
   * Performs some static checks, notably:
   * - opcode of first instruction begins at index 0
   * - only documented instructions may appear
   * - each instruction follows the last
   * - last byte of last instruction is at (code_length-1)
   *
   * Logs an error and returns "false" on failure.
   */
  bool ComputeWidthsAndCountOps();

  /*
   * Set the "in try" flags for all instructions protected by "try" statements. Also sets the
   * "branch target" flags for exception handlers.
   *
   * Call this after widths have been set in "insn_flags".
   *
   * Returns "false" if something in the exception table looks fishy, but we're expecting the
   * exception table to be valid.
   */
  bool ScanTryCatchBlocks() REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Perform static verification on all instructions in a method.
   *
   * Walks through instructions in a method calling VerifyInstruction on each.
   */
  template <bool kAllowRuntimeOnlyInstructions>
  bool VerifyInstructions();

  /*
   * Perform static verification on an instruction.
   *
   * As a side effect, this sets the "branch target" flags in InsnFlags.
   *
   * "(CF)" items are handled during code-flow analysis.
   *
   * v3 4.10.1
   * - target of each jump and branch instruction must be valid
   * - targets of switch statements must be valid
   * - operands referencing constant pool entries must be valid
   * - (CF) operands of getfield, putfield, getstatic, putstatic must be valid
   * - (CF) operands of method invocation instructions must be valid
   * - (CF) only invoke-direct can call a method starting with '<'
   * - (CF) <clinit> must never be called explicitly
   * - operands of instanceof, checkcast, new (and variants) must be valid
   * - new-array[-type] limited to 255 dimensions
   * - can't use "new" on an array class
   * - (?) limit dimensions in multi-array creation
   * - local variable load/store register values must be in valid range
   *
   * v3 4.11.1.2
   * - branches must be within the bounds of the code array
   * - targets of all control-flow instructions are the start of an instruction
   * - register accesses fall within range of allocated registers
   * - (N/A) access to constant pool must be of appropriate type
   * - code does not end in the middle of an instruction
   * - execution cannot fall off the end of the code
   * - (earlier) for each exception handler, the "try" area must begin and
   *   end at the start of an instruction (end can be at the end of the code)
   * - (earlier) for each exception handler, the handler must start at a valid
   *   instruction
   */
  template <bool kAllowRuntimeOnlyInstructions>
  bool VerifyInstruction(const Instruction* inst, uint32_t code_offset);

  /* Ensure that the register index is valid for this code item. */
  bool CheckRegisterIndex(uint32_t idx) {
    if (UNLIKELY(idx >= code_item_accessor_.RegistersSize())) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "register index out of range (" << idx << " >= "
                                        << code_item_accessor_.RegistersSize() << ")";
      return false;
    }
    return true;
  }

  /* Ensure that the wide register index is valid for this code item. */
  bool CheckWideRegisterIndex(uint32_t idx) {
    if (UNLIKELY(idx + 1 >= code_item_accessor_.RegistersSize())) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "wide register index out of range (" << idx
                                        << "+1 >= " << code_item_accessor_.RegistersSize() << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on an instruction referencing a CallSite. All we do here is ensure that
  // the call site index is in the valid range.
  bool CheckCallSiteIndex(uint32_t idx) {
    uint32_t limit = dex_file_->NumCallSiteIds();
    if (UNLIKELY(idx >= limit)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad call site index " << idx << " (max "
                                        << limit << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on a field Get or set instruction. All we do here is ensure that the
  // field index is in the valid range.
  bool CheckFieldIndex(uint32_t idx) {
    if (UNLIKELY(idx >= dex_file_->GetHeader().field_ids_size_)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad field index " << idx << " (max "
                                        << dex_file_->GetHeader().field_ids_size_ << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on a method invocation instruction. All we do here is ensure that the
  // method index is in the valid range.
  bool CheckMethodIndex(uint32_t idx) {
    if (UNLIKELY(idx >= dex_file_->GetHeader().method_ids_size_)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad method index " << idx << " (max "
                                        << dex_file_->GetHeader().method_ids_size_ << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on an instruction referencing a constant method handle. All we do here
  // is ensure that the method index is in the valid range.
  bool CheckMethodHandleIndex(uint32_t idx) {
    uint32_t limit = dex_file_->NumMethodHandles();
    if (UNLIKELY(idx >= limit)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad method handle index " << idx << " (max "
                                        << limit << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on a "new-instance" instruction. Specifically, make sure the class
  // reference isn't for an array class.
  bool CheckNewInstance(dex::TypeIndex idx);

  // Perform static checks on a prototype indexing instruction. All we do here is ensure that the
  // prototype index is in the valid range.
  bool CheckPrototypeIndex(uint32_t idx) {
    if (UNLIKELY(idx >= dex_file_->GetHeader().proto_ids_size_)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad prototype index " << idx << " (max "
                                        << dex_file_->GetHeader().proto_ids_size_ << ")";
      return false;
    }
    return true;
  }

  /* Ensure that the string index is in the valid range. */
  bool CheckStringIndex(uint32_t idx) {
    if (UNLIKELY(idx >= dex_file_->GetHeader().string_ids_size_)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad string index " << idx << " (max "
                                        << dex_file_->GetHeader().string_ids_size_ << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on an instruction that takes a class constant. Ensure that the class
  // index is in the valid range.
  bool CheckTypeIndex(dex::TypeIndex idx) {
    if (UNLIKELY(idx.index_ >= dex_file_->GetHeader().type_ids_size_)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad type index " << idx.index_ << " (max "
                                        << dex_file_->GetHeader().type_ids_size_ << ")";
      return false;
    }
    return true;
  }

  // Perform static checks on a "new-array" instruction. Specifically, make sure they aren't
  // creating an array of arrays that causes the number of dimensions to exceed 255.
  bool CheckNewArray(dex::TypeIndex idx);

  // Verify an array data table. "cur_offset" is the offset of the fill-array-data instruction.
  bool CheckArrayData(uint32_t cur_offset);

  // Verify that the target of a branch instruction is valid. We don't expect code to jump directly
  // into an exception handler, but it's valid to do so as long as the target isn't a
  // "move-exception" instruction. We verify that in a later stage.
  // The dex format forbids certain instructions from branching to themselves.
  // Updates "insn_flags_", setting the "branch target" flag.
  bool CheckBranchTarget(uint32_t cur_offset);

  // Verify a switch table. "cur_offset" is the offset of the switch instruction.
  // Updates "insn_flags_", setting the "branch target" flag.
  bool CheckSwitchTargets(uint32_t cur_offset);

  // Check the register indices used in a "vararg" instruction, such as invoke-virtual or
  // filled-new-array.
  // - vA holds word count (0-5), args[] have values.
  // There are some tests we don't do here, e.g. we don't try to verify that invoking a method that
  // takes a double is done with consecutive registers. This requires parsing the target method
  // signature, which we will be doing later on during the code flow analysis.
  bool CheckVarArgRegs(uint32_t vA, uint32_t arg[]) {
    uint16_t registers_size = code_item_accessor_.RegistersSize();
    for (uint32_t idx = 0; idx < vA; idx++) {
      if (UNLIKELY(arg[idx] >= registers_size)) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid reg index (" << arg[idx]
                                          << ") in non-range invoke (>= " << registers_size << ")";
        return false;
      }
    }

    return true;
  }

  // Check the register indices used in a "vararg/range" instruction, such as invoke-virtual/range
  // or filled-new-array/range.
  // - vA holds word count, vC holds index of first reg.
  bool CheckVarArgRangeRegs(uint32_t vA, uint32_t vC) {
    uint16_t registers_size = code_item_accessor_.RegistersSize();
    // vA/vC are unsigned 8-bit/16-bit quantities for /range instructions, so there's no risk of
    // integer overflow when adding them here.
    if (UNLIKELY(vA + vC > registers_size)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid reg index " << vA << "+" << vC
                                        << " in range invoke (> " << registers_size << ")";
      return false;
    }
    return true;
  }

  // Checks the method matches the expectations required to be signature polymorphic.
  bool CheckSignaturePolymorphicMethod(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_);

  // Checks the invoked receiver matches the expectations for signature polymorphic methods.
  bool CheckSignaturePolymorphicReceiver(const Instruction* inst) REQUIRES_SHARED(Locks::mutator_lock_);

  // Extract the relative offset from a branch instruction.
  // Returns "false" on failure (e.g. this isn't a branch instruction).
  bool GetBranchOffset(uint32_t cur_offset, int32_t* pOffset, bool* pConditional,
                       bool* selfOkay);

  /* Perform detailed code-flow analysis on a single method. */
  bool VerifyCodeFlow() REQUIRES_SHARED(Locks::mutator_lock_);

  // Set the register types for the first instruction in the method based on the method signature.
  // This has the side-effect of validating the signature.
  bool SetTypesFromSignature() REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Perform code flow on a method.
   *
   * The basic strategy is as outlined in v3 4.11.1.2: set the "changed" bit on the first
   * instruction, process it (setting additional "changed" bits), and repeat until there are no
   * more.
   *
   * v3 4.11.1.1
   * - (N/A) operand stack is always the same size
   * - operand stack [registers] contain the correct types of values
   * - local variables [registers] contain the correct types of values
   * - methods are invoked with the appropriate arguments
   * - fields are assigned using values of appropriate types
   * - opcodes have the correct type values in operand registers
   * - there is never an uninitialized class instance in a local variable in code protected by an
   *   exception handler (operand stack is okay, because the operand stack is discarded when an
   *   exception is thrown) [can't know what's a local var w/o the debug info -- should fall out of
   *   register typing]
   *
   * v3 4.11.1.2
   * - execution cannot fall off the end of the code
   *
   * (We also do many of the items described in the "static checks" sections, because it's easier to
   * do them here.)
   *
   * We need an array of RegType values, one per register, for every instruction. If the method uses
   * monitor-enter, we need extra data for every register, and a stack for every "interesting"
   * instruction. In theory this could become quite large -- up to several megabytes for a monster
   * function.
   *
   * NOTE:
   * The spec forbids backward branches when there's an uninitialized reference in a register. The
   * idea is to prevent something like this:
   *   loop:
   *     move r1, r0
   *     new-instance r0, MyClass
   *     ...
   *     if-eq rN, loop  // once
   *   initialize r0
   *
   * This leaves us with two different instances, both allocated by the same instruction, but only
   * one is initialized. The scheme outlined in v3 4.11.1.4 wouldn't catch this, so they work around
   * it by preventing backward branches. We achieve identical results without restricting code
   * reordering by specifying that you can't execute the new-instance instruction if a register
   * contains an uninitialized instance created by that same instruction.
   */
  template <bool kMonitorDexPCs>
  bool CodeFlowVerifyMethod() REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Perform verification for a single instruction.
   *
   * This requires fully decoding the instruction to determine the effect it has on registers.
   *
   * Finds zero or more following instructions and sets the "changed" flag if execution at that
   * point needs to be (re-)evaluated. Register changes are merged into "reg_types_" at the target
   * addresses. Does not set or clear any other flags in "insn_flags_".
   */
  bool CodeFlowVerifyInstruction(uint32_t* start_guess)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Perform verification of a new array instruction
  void VerifyNewArray(const Instruction* inst, bool is_filled, bool is_range)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Helper to perform verification on puts of primitive type.
  void VerifyPrimitivePut(const RegType& target_type, const RegType& insn_type,
                          const uint32_t vregA) REQUIRES_SHARED(Locks::mutator_lock_);

  // Perform verification of an aget instruction. The destination register's type will be set to
  // be that of component type of the array unless the array type is unknown, in which case a
  // bottom type inferred from the type of instruction is used. is_primitive is false for an
  // aget-object.
  void VerifyAGet(const Instruction* inst, const RegType& insn_type,
                  bool is_primitive) REQUIRES_SHARED(Locks::mutator_lock_);

  // Perform verification of an aput instruction.
  void VerifyAPut(const Instruction* inst, const RegType& insn_type,
                  bool is_primitive) REQUIRES_SHARED(Locks::mutator_lock_);

  // Lookup instance field and fail for resolution violations
  ArtField* GetInstanceField(const RegType& obj_type, int field_idx)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Lookup static field and fail for resolution violations
  ArtField* GetStaticField(int field_idx) REQUIRES_SHARED(Locks::mutator_lock_);

  // Perform verification of an iget/sget/iput/sput instruction.
  template <FieldAccessType kAccType>
  void VerifyISFieldAccess(const Instruction* inst, const RegType& insn_type,
                           bool is_primitive, bool is_static)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Resolves a class based on an index and, if C is kYes, performs access checks to ensure
  // the referrer can access the resolved class.
  template <CheckAccess C>
  const RegType& ResolveClass(dex::TypeIndex class_idx)
      REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * For the "move-exception" instruction at "work_insn_idx_", which must be at an exception handler
   * address, determine the Join of all exceptions that can land here. Fails if no matching
   * exception handler can be found or if the Join of exception types fails.
   */
  const RegType& GetCaughtExceptionType()
      REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Resolves a method based on an index and performs access checks to ensure
   * the referrer can access the resolved method.
   * Does not throw exceptions.
   */
  ArtMethod* ResolveMethodAndCheckAccess(uint32_t method_idx, MethodType method_type)
      REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Verify the arguments to a method. We're executing in "method", making
   * a call to the method reference in vB.
   *
   * If this is a "direct" invoke, we allow calls to <init>. For calls to
   * <init>, the first argument may be an uninitialized reference. Otherwise,
   * calls to anything starting with '<' will be rejected, as will any
   * uninitialized reference arguments.
   *
   * For non-static method calls, this will verify that the method call is
   * appropriate for the "this" argument.
   *
   * The method reference is in vBBBB. The "is_range" parameter determines
   * whether we use 0-4 "args" values or a range of registers defined by
   * vAA and vCCCC.
   *
   * Widening conversions on integers and references are allowed, but
   * narrowing conversions are not.
   *
   * Returns the resolved method on success, null on failure (with *failure
   * set appropriately).
   */
  ArtMethod* VerifyInvocationArgs(const Instruction* inst, MethodType method_type, bool is_range)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Similar checks to the above, but on the proto. Will be used when the method cannot be
  // resolved.
  void VerifyInvocationArgsUnresolvedMethod(const Instruction* inst, MethodType method_type,
                                            bool is_range)
      REQUIRES_SHARED(Locks::mutator_lock_);

  template <class T>
  ArtMethod* VerifyInvocationArgsFromIterator(T* it, const Instruction* inst,
                                                      MethodType method_type, bool is_range,
                                                      ArtMethod* res_method)
      REQUIRES_SHARED(Locks::mutator_lock_);

  /*
   * Verify the arguments present for a call site. Returns "true" if all is well, "false" otherwise.
   */
  bool CheckCallSite(uint32_t call_site_idx);

  /*
   * Verify that the target instruction is not "move-exception". It's important that the only way
   * to execute a move-exception is as the first instruction of an exception handler.
   * Returns "true" if all is well, "false" if the target instruction is move-exception.
   */
  bool CheckNotMoveException(const uint16_t* insns, int insn_idx) {
    if ((insns[insn_idx] & 0xff) == Instruction::MOVE_EXCEPTION) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid use of move-exception";
      return false;
    }
    return true;
  }

  /*
   * Verify that the target instruction is not "move-result". It is important that we cannot
   * branch to move-result instructions, but we have to make this a distinct check instead of
   * adding it to CheckNotMoveException, because it is legal to continue into "move-result"
   * instructions - as long as the previous instruction was an invoke, which is checked elsewhere.
   */
  bool CheckNotMoveResult(const uint16_t* insns, int insn_idx) {
    if (((insns[insn_idx] & 0xff) >= Instruction::MOVE_RESULT) &&
        ((insns[insn_idx] & 0xff) <= Instruction::MOVE_RESULT_OBJECT)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid use of move-result*";
      return false;
    }
    return true;
  }

  /*
   * Verify that the target instruction is not "move-result" or "move-exception". This is to
   * be used when checking branch and switch instructions, but not instructions that can
   * continue.
   */
  bool CheckNotMoveExceptionOrMoveResult(const uint16_t* insns, int insn_idx) {
    return (CheckNotMoveException(insns, insn_idx) && CheckNotMoveResult(insns, insn_idx));
  }

  /*
  * Control can transfer to "next_insn". Merge the registers from merge_line into the table at
  * next_insn, and set the changed flag on the target address if any of the registers were changed.
  * In the case of fall-through, update the merge line on a change as its the working line for the
  * next instruction.
  * Returns "false" if an error is encountered.
  */
  bool UpdateRegisters(uint32_t next_insn, RegisterLine* merge_line, bool update_merge_line)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Return the register type for the method.
  const RegType& GetMethodReturnType() REQUIRES_SHARED(Locks::mutator_lock_);

  // Get a type representing the declaring class of the method.
  const RegType& GetDeclaringClass() REQUIRES_SHARED(Locks::mutator_lock_) {
    if (declaring_class_ == nullptr) {
      const dex::MethodId& method_id = dex_file_->GetMethodId(dex_method_idx_);
      const char* descriptor
          = dex_file_->GetTypeDescriptor(dex_file_->GetTypeId(method_id.class_idx_));
      declaring_class_ = &reg_types_.FromDescriptor(class_loader_, descriptor);
    }
    return *declaring_class_;
  }

  InstructionFlags* CurrentInsnFlags() {
    return &GetModifiableInstructionFlags(work_insn_idx_);
  }

  const RegType& DetermineCat1Constant(int32_t value)
      REQUIRES_SHARED(Locks::mutator_lock_);

  // Try to create a register type from the given class. In case a precise type is requested, but
  // the class is not instantiable, a soft error (of type NO_CLASS) will be enqueued and a
  // non-precise reference will be returned.
  // Note: we reuse NO_CLASS as this will throw an exception at runtime, when the failing class is
  //       actually touched.
  const RegType& FromClass(const char* descriptor, ObjPtr<mirror::Class> klass, bool precise)
      REQUIRES_SHARED(Locks::mutator_lock_) {
    DCHECK(klass != nullptr);
    if (precise && !klass->IsInstantiable() && !klass->IsPrimitive()) {
      Fail(VerifyError::VERIFY_ERROR_NO_CLASS) << "Could not create precise reference for "
          << "non-instantiable klass " << descriptor;
      precise = false;
    }
    return reg_types_.FromClass(descriptor, klass, precise);
  }

  ALWAYS_INLINE bool FailOrAbort(bool condition, const char* error_msg, uint32_t work_insn_idx);

  ALWAYS_INLINE InstructionFlags& GetModifiableInstructionFlags(size_t index) {
    return insn_flags_[index];
  }

  // Returns the method index of an invoke instruction.
  uint16_t GetMethodIdxOfInvoke(const Instruction* inst)
      REQUIRES_SHARED(Locks::mutator_lock_) {
    return inst->VRegB();
  }
  // Returns the field index of a field access instruction.
  uint16_t GetFieldIdxOfFieldAccess(const Instruction* inst, bool is_static)
      REQUIRES_SHARED(Locks::mutator_lock_) {
    if (is_static) {
      return inst->VRegB_21c();
    } else {
      return inst->VRegC_22c();
    }
  }

  // Run verification on the method. Returns true if verification completes and false if the input
  // has an irrecoverable corruption.
  bool Verify() override REQUIRES_SHARED(Locks::mutator_lock_);

  // For app-compatibility, code after a runtime throw is treated as dead code
  // for apps targeting <= S.
  // Returns whether the current instruction was marked as throwing.
  bool PotentiallyMarkRuntimeThrow() override;

  // Dump the failures encountered by the verifier.
  std::ostream& DumpFailures(std::ostream& os) {
    DCHECK_EQ(failures_.size(), failure_messages_.size());
    for (const auto* stream : failure_messages_) {
        os << stream->str() << "\n";
    }
    return os;
  }

  // Dump the state of the verifier, namely each instruction, what flags are set on it, register
  // information
  void Dump(std::ostream& os) REQUIRES_SHARED(Locks::mutator_lock_) {
    VariableIndentationOutputStream vios(&os);
    Dump(&vios);
  }
  void Dump(VariableIndentationOutputStream* vios) REQUIRES_SHARED(Locks::mutator_lock_);

  bool HandleMoveException(const Instruction* inst) REQUIRES_SHARED(Locks::mutator_lock_);

  const uint32_t method_access_flags_;  // Method's access flags.
  const RegType* return_type_;  // Lazily computed return type of the method.
  // The dex_cache for the declaring class of the method.
  Handle<mirror::DexCache> dex_cache_ GUARDED_BY(Locks::mutator_lock_);
  // The class loader for the declaring class of the method.
  Handle<mirror::ClassLoader> class_loader_ GUARDED_BY(Locks::mutator_lock_);
  const RegType* declaring_class_;  // Lazily computed reg type of the method's declaring class.

  // The dex PC of a FindLocksAtDexPc request, -1 otherwise.
  uint32_t interesting_dex_pc_;
  // The container into which FindLocksAtDexPc should write the registers containing held locks,
  // null if we're not doing FindLocksAtDexPc.
  std::vector<DexLockInfo>* monitor_enter_dex_pcs_;

  // Indicates whether we verify to dump the info. In that case we accept quickened instructions
  // even though we might detect to be a compiler. Should only be set when running
  // VerifyMethodAndDump.
  const bool verify_to_dump_;

  // Whether or not we call AllowThreadSuspension periodically, we want a way to disable this for
  // thread dumping checkpoints since we may get thread suspension at an inopportune time due to
  // FindLocksAtDexPC, resulting in deadlocks.
  const bool allow_thread_suspension_;

  // Whether the method seems to be a constructor. Note that this field exists as we can't trust
  // the flags in the dex file. Some older code does not mark methods named "<init>" and "<clinit>"
  // correctly.
  //
  // Note: this flag is only valid once Verify() has started.
  bool is_constructor_;

  // API level, for dependent checks. Note: we do not use '0' for unset here, to simplify checks.
  // Instead, unset level should correspond to max().
  const uint32_t api_level_;

  friend class ::art::verifier::MethodVerifier;

  DISALLOW_COPY_AND_ASSIGN(MethodVerifier);
};

// Note: returns true on failure.
template <bool kVerifierDebug>
inline bool MethodVerifier<kVerifierDebug>::FailOrAbort(bool condition,
                                                        const char* error_msg,
                                                        uint32_t work_insn_idx) {
  if (kIsDebugBuild) {
    // In a debug build, abort if the error condition is wrong. Only warn if
    // we are already aborting (as this verification is likely run to print
    // lock information).
    if (LIKELY(gAborting == 0)) {
      DCHECK(condition) << error_msg << work_insn_idx << " "
                        << dex_file_->PrettyMethod(dex_method_idx_);
    } else {
      if (!condition) {
        LOG(ERROR) << error_msg << work_insn_idx;
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << error_msg << work_insn_idx;
        return true;
      }
    }
  } else {
    // In a non-debug build, just fail the class.
    if (!condition) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << error_msg << work_insn_idx;
      return true;
    }
  }

  return false;
}

static bool IsLargeMethod(const CodeItemDataAccessor& accessor) {
  if (!accessor.HasCodeItem()) {
    return false;
  }

  uint16_t registers_size = accessor.RegistersSize();
  uint32_t insns_size = accessor.InsnsSizeInCodeUnits();

  return registers_size * insns_size > 4*1024*1024;
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::FindLocksAtDexPc() {
  CHECK(monitor_enter_dex_pcs_ != nullptr);
  CHECK(code_item_accessor_.HasCodeItem());  // This only makes sense for methods with code.

  // Quick check whether there are any monitor_enter instructions before verifying.
  for (const DexInstructionPcPair& inst : code_item_accessor_) {
    if (inst->Opcode() == Instruction::MONITOR_ENTER) {
      // Strictly speaking, we ought to be able to get away with doing a subset of the full method
      // verification. In practice, the phase we want relies on data structures set up by all the
      // earlier passes, so we just run the full method verification and bail out early when we've
      // got what we wanted.
      Verify();
      return;
    }
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::Verify() {
  // Some older code doesn't correctly mark constructors as such. Test for this case by looking at
  // the name.
  const dex::MethodId& method_id = dex_file_->GetMethodId(dex_method_idx_);
  const std::string_view method_name = dex_file_->GetStringView(method_id.name_idx_);
  bool instance_constructor_by_name = method_name == "<init>";
  bool static_constructor_by_name = method_name == "<clinit>";
  bool constructor_by_name = instance_constructor_by_name || static_constructor_by_name;
  // Check that only constructors are tagged, and check for bad code that doesn't tag constructors.
  if ((method_access_flags_ & kAccConstructor) != 0) {
    if (!constructor_by_name) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD)
            << "method is marked as constructor, but not named accordingly";
      return false;
    }
    is_constructor_ = true;
  } else if (constructor_by_name) {
    LOG(WARNING) << "Method " << dex_file_->PrettyMethod(dex_method_idx_)
                 << " not marked as constructor.";
    is_constructor_ = true;
  }
  // If it's a constructor, check whether IsStatic() matches the name.
  // This should have been rejected by the dex file verifier. Only do in debug build.
  if (kIsDebugBuild) {
    if (IsConstructor()) {
      if (IsStatic() ^ static_constructor_by_name) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD)
              << "constructor name doesn't match static flag";
        return false;
      }
    }
  }

  // Methods may only have one of public/protected/private.
  // This should have been rejected by the dex file verifier. Only do in debug build.
  if (kIsDebugBuild) {
    size_t access_mod_count =
        (((method_access_flags_ & kAccPublic) == 0) ? 0 : 1) +
        (((method_access_flags_ & kAccProtected) == 0) ? 0 : 1) +
        (((method_access_flags_ & kAccPrivate) == 0) ? 0 : 1);
    if (access_mod_count > 1) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "method has more than one of public/protected/private";
      return false;
    }
  }

  // If there aren't any instructions, make sure that's expected, then exit successfully.
  if (!code_item_accessor_.HasCodeItem()) {
    // Only native or abstract methods may not have code.
    if ((method_access_flags_ & (kAccNative | kAccAbstract)) == 0) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "zero-length code in concrete non-native method";
      return false;
    }

    // Test FastNative and CriticalNative annotations. We do this in the
    // verifier for convenience.
    if ((method_access_flags_ & kAccNative) != 0) {
      // Fetch the flags from the annotations: the class linker hasn't processed
      // them yet.
      uint32_t native_access_flags = annotations::GetNativeMethodAnnotationAccessFlags(
          *dex_file_, class_def_, dex_method_idx_);
      if ((native_access_flags & kAccFastNative) != 0) {
        if ((method_access_flags_ & kAccSynchronized) != 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "fast native methods cannot be synchronized";
          return false;
        }
      }
      if ((native_access_flags & kAccCriticalNative) != 0) {
        if ((method_access_flags_ & kAccSynchronized) != 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "critical native methods cannot be synchronized";
          return false;
        }
        if ((method_access_flags_ & kAccStatic) == 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "critical native methods must be static";
          return false;
        }
        const char* shorty = dex_file_->GetMethodShorty(method_id);
        for (size_t i = 0, len = strlen(shorty); i < len; ++i) {
          if (Primitive::GetType(shorty[i]) == Primitive::kPrimNot) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) <<
                "critical native methods must not have references as arguments or return type";
            return false;
          }
        }
      }
    }

    // This should have been rejected by the dex file verifier. Only do in debug build.
    // Note: the above will also be rejected in the dex file verifier, starting in dex version 37.
    if (kIsDebugBuild) {
      if ((method_access_flags_ & kAccAbstract) != 0) {
        // Abstract methods are not allowed to have the following flags.
        static constexpr uint32_t kForbidden =
            kAccPrivate |
            kAccStatic |
            kAccFinal |
            kAccNative |
            kAccStrict |
            kAccSynchronized;
        if ((method_access_flags_ & kForbidden) != 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD)
                << "method can't be abstract and private/static/final/native/strict/synchronized";
          return false;
        }
      }
      if ((class_def_.GetJavaAccessFlags() & kAccInterface) != 0) {
        // Interface methods must be public and abstract (if default methods are disabled).
        uint32_t kRequired = kAccPublic;
        if ((method_access_flags_ & kRequired) != kRequired) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "interface methods must be public";
          return false;
        }
        // In addition to the above, interface methods must not be protected.
        static constexpr uint32_t kForbidden = kAccProtected;
        if ((method_access_flags_ & kForbidden) != 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "interface methods can't be protected";
          return false;
        }
      }
      // We also don't allow constructors to be abstract or native.
      if (IsConstructor()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "constructors can't be abstract or native";
        return false;
      }
    }
    return true;
  }

  // This should have been rejected by the dex file verifier. Only do in debug build.
  if (kIsDebugBuild) {
    // When there's code, the method must not be native or abstract.
    if ((method_access_flags_ & (kAccNative | kAccAbstract)) != 0) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "non-zero-length code in abstract or native method";
      return false;
    }

    if ((class_def_.GetJavaAccessFlags() & kAccInterface) != 0) {
      // Interfaces may always have static initializers for their fields. If we are running with
      // default methods enabled we also allow other public, static, non-final methods to have code.
      // Otherwise that is the only type of method allowed.
      if (!(IsConstructor() && IsStatic())) {
        if (IsInstanceConstructor()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "interfaces may not have non-static constructor";
          return false;
        } else if (method_access_flags_ & kAccFinal) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "interfaces may not have final methods";
          return false;
        } else {
          uint32_t access_flag_options = kAccPublic;
          if (dex_file_->SupportsDefaultMethods()) {
            access_flag_options |= kAccPrivate;
          }
          if (!(method_access_flags_ & access_flag_options)) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD)
                << "interfaces may not have protected or package-private members";
            return false;
          }
        }
      }
    }

    // Instance constructors must not be synchronized.
    if (IsInstanceConstructor()) {
      static constexpr uint32_t kForbidden = kAccSynchronized;
      if ((method_access_flags_ & kForbidden) != 0) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "constructors can't be synchronized";
        return false;
      }
    }
  }

  // Consistency-check of the register counts.
  // ins + locals = registers, so make sure that ins <= registers.
  if (code_item_accessor_.InsSize() > code_item_accessor_.RegistersSize()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad register counts (ins="
                                      << code_item_accessor_.InsSize()
                                      << " regs=" << code_item_accessor_.RegistersSize();
    return false;
  }

  // Allocate and initialize an array to hold instruction data.
  insn_flags_.reset(allocator_.AllocArray<InstructionFlags>(
      code_item_accessor_.InsnsSizeInCodeUnits()));
  DCHECK(insn_flags_ != nullptr);
  std::uninitialized_fill_n(insn_flags_.get(),
                            code_item_accessor_.InsnsSizeInCodeUnits(),
                            InstructionFlags());
  // Run through the instructions and see if the width checks out.
  bool result = ComputeWidthsAndCountOps();
  bool allow_runtime_only_instructions = !IsAotMode() || verify_to_dump_;
  // Flag instructions guarded by a "try" block and check exception handlers.
  result = result && ScanTryCatchBlocks();
  // Perform static instruction verification.
  result = result && (allow_runtime_only_instructions
                          ? VerifyInstructions<true>()
                          : VerifyInstructions<false>());
  // Perform code-flow analysis and return.
  result = result && VerifyCodeFlow();

  return result;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::ComputeWidthsAndCountOps() {
  // We can't assume the instruction is well formed, handle the case where calculating the size
  // goes past the end of the code item.
  SafeDexInstructionIterator it(code_item_accessor_.begin(), code_item_accessor_.end());
  if (it == code_item_accessor_.end()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "code item has no opcode";
    return false;
  }
  for ( ; !it.IsErrorState() && it < code_item_accessor_.end(); ++it) {
    // In case the instruction goes past the end of the code item, make sure to not process it.
    SafeDexInstructionIterator next = it;
    ++next;
    if (next.IsErrorState()) {
      break;
    }
    GetModifiableInstructionFlags(it.DexPc()).SetIsOpcode();
  }

  if (it != code_item_accessor_.end()) {
    const size_t insns_size = code_item_accessor_.InsnsSizeInCodeUnits();
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "code did not end where expected ("
                                      << it.DexPc() << " vs. " << insns_size << ")";
    return false;
  }
  DCHECK(GetInstructionFlags(0).IsOpcode());

  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::ScanTryCatchBlocks() {
  const uint32_t tries_size = code_item_accessor_.TriesSize();
  if (tries_size == 0) {
    return true;
  }
  const uint32_t insns_size = code_item_accessor_.InsnsSizeInCodeUnits();
  for (const dex::TryItem& try_item : code_item_accessor_.TryItems()) {
    const uint32_t start = try_item.start_addr_;
    const uint32_t end = start + try_item.insn_count_;
    if ((start >= end) || (start >= insns_size) || (end > insns_size)) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad exception entry: startAddr=" << start
                                        << " endAddr=" << end << " (size=" << insns_size << ")";
      return false;
    }
    if (!GetInstructionFlags(start).IsOpcode()) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD)
          << "'try' block starts inside an instruction (" << start << ")";
      return false;
    }
    DexInstructionIterator end_it(code_item_accessor_.Insns(), end);
    for (DexInstructionIterator it(code_item_accessor_.Insns(), start); it < end_it; ++it) {
      GetModifiableInstructionFlags(it.DexPc()).SetInTry();
    }
  }
  // Iterate over each of the handlers to verify target addresses.
  const uint8_t* handlers_ptr = code_item_accessor_.GetCatchHandlerData();
  const uint32_t handlers_size = DecodeUnsignedLeb128(&handlers_ptr);
  ClassLinker* linker = GetClassLinker();
  for (uint32_t idx = 0; idx < handlers_size; idx++) {
    CatchHandlerIterator iterator(handlers_ptr);
    for (; iterator.HasNext(); iterator.Next()) {
      uint32_t dex_pc = iterator.GetHandlerAddress();
      if (!GetInstructionFlags(dex_pc).IsOpcode()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD)
            << "exception handler starts at bad address (" << dex_pc << ")";
        return false;
      }
      if (!CheckNotMoveResult(code_item_accessor_.Insns(), dex_pc)) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD)
            << "exception handler begins with move-result* (" << dex_pc << ")";
        return false;
      }
      GetModifiableInstructionFlags(dex_pc).SetBranchTarget();
      // Ensure exception types are resolved so that they don't need resolution to be delivered,
      // unresolved exception types will be ignored by exception delivery
      if (iterator.GetHandlerTypeIndex().IsValid()) {
        ObjPtr<mirror::Class> exception_type =
            linker->ResolveType(iterator.GetHandlerTypeIndex(), dex_cache_, class_loader_);
        if (exception_type == nullptr) {
          DCHECK(self_->IsExceptionPending());
          self_->ClearException();
        }
      }
    }
    handlers_ptr = iterator.EndDataPointer();
  }
  return true;
}

template <bool kVerifierDebug>
template <bool kAllowRuntimeOnlyInstructions>
bool MethodVerifier<kVerifierDebug>::VerifyInstructions() {
  // Flag the start of the method as a branch target.
  GetModifiableInstructionFlags(0).SetBranchTarget();
  for (const DexInstructionPcPair& inst : code_item_accessor_) {
    const uint32_t dex_pc = inst.DexPc();
    if (!VerifyInstruction<kAllowRuntimeOnlyInstructions>(&inst.Inst(), dex_pc)) {
      DCHECK_NE(failures_.size(), 0U);
      return false;
    }
    // Flag some interesting instructions.
    if (inst->IsReturn()) {
      GetModifiableInstructionFlags(dex_pc).SetReturn();
    } else if (inst->Opcode() == Instruction::CHECK_CAST) {
      // The dex-to-dex compiler wants type information to elide check-casts.
      GetModifiableInstructionFlags(dex_pc).SetCompileTimeInfoPoint();
    }
  }
  return true;
}

template <bool kVerifierDebug>
template <bool kAllowRuntimeOnlyInstructions>
bool MethodVerifier<kVerifierDebug>::VerifyInstruction(const Instruction* inst,
                                                       uint32_t code_offset) {
  bool result = true;
  switch (inst->GetVerifyTypeArgumentA()) {
    case Instruction::kVerifyRegA:
      result = result && CheckRegisterIndex(inst->VRegA());
      break;
    case Instruction::kVerifyRegAWide:
      result = result && CheckWideRegisterIndex(inst->VRegA());
      break;
  }
  switch (inst->GetVerifyTypeArgumentB()) {
    case Instruction::kVerifyRegB:
      result = result && CheckRegisterIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBField:
      result = result && CheckFieldIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBMethod:
      result = result && CheckMethodIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBNewInstance:
      result = result && CheckNewInstance(dex::TypeIndex(inst->VRegB()));
      break;
    case Instruction::kVerifyRegBString:
      result = result && CheckStringIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBType:
      result = result && CheckTypeIndex(dex::TypeIndex(inst->VRegB()));
      break;
    case Instruction::kVerifyRegBWide:
      result = result && CheckWideRegisterIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBCallSite:
      result = result && CheckCallSiteIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBMethodHandle:
      result = result && CheckMethodHandleIndex(inst->VRegB());
      break;
    case Instruction::kVerifyRegBPrototype:
      result = result && CheckPrototypeIndex(inst->VRegB());
      break;
  }
  switch (inst->GetVerifyTypeArgumentC()) {
    case Instruction::kVerifyRegC:
      result = result && CheckRegisterIndex(inst->VRegC());
      break;
    case Instruction::kVerifyRegCField:
      result = result && CheckFieldIndex(inst->VRegC());
      break;
    case Instruction::kVerifyRegCNewArray:
      result = result && CheckNewArray(dex::TypeIndex(inst->VRegC()));
      break;
    case Instruction::kVerifyRegCType:
      result = result && CheckTypeIndex(dex::TypeIndex(inst->VRegC()));
      break;
    case Instruction::kVerifyRegCWide:
      result = result && CheckWideRegisterIndex(inst->VRegC());
      break;
  }
  switch (inst->GetVerifyTypeArgumentH()) {
    case Instruction::kVerifyRegHPrototype:
      result = result && CheckPrototypeIndex(inst->VRegH());
      break;
  }
  switch (inst->GetVerifyExtraFlags()) {
    case Instruction::kVerifyArrayData:
      result = result && CheckArrayData(code_offset);
      break;
    case Instruction::kVerifyBranchTarget:
      result = result && CheckBranchTarget(code_offset);
      break;
    case Instruction::kVerifySwitchTargets:
      result = result && CheckSwitchTargets(code_offset);
      break;
    case Instruction::kVerifyVarArgNonZero:
      // Fall-through.
    case Instruction::kVerifyVarArg: {
      // Instructions that can actually return a negative value shouldn't have this flag.
      uint32_t v_a = dchecked_integral_cast<uint32_t>(inst->VRegA());
      if ((inst->GetVerifyExtraFlags() == Instruction::kVerifyVarArgNonZero && v_a == 0) ||
          v_a > Instruction::kMaxVarArgRegs) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid arg count (" << v_a << ") in "
                                             "non-range invoke";
        return false;
      }

      uint32_t args[Instruction::kMaxVarArgRegs];
      inst->GetVarArgs(args);
      result = result && CheckVarArgRegs(v_a, args);
      break;
    }
    case Instruction::kVerifyVarArgRangeNonZero:
      // Fall-through.
    case Instruction::kVerifyVarArgRange:
      if (inst->GetVerifyExtraFlags() == Instruction::kVerifyVarArgRangeNonZero &&
          inst->VRegA() <= 0) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid arg count (" << inst->VRegA() << ") in "
                                             "range invoke";
        return false;
      }
      result = result && CheckVarArgRangeRegs(inst->VRegA(), inst->VRegC());
      break;
    case Instruction::kVerifyError:
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected opcode " << inst->Name();
      result = false;
      break;
  }
  if (!kAllowRuntimeOnlyInstructions && inst->GetVerifyIsRuntimeOnly()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "opcode only expected at runtime " << inst->Name();
    result = false;
  }
  return result;
}

template <bool kVerifierDebug>
inline bool MethodVerifier<kVerifierDebug>::CheckNewInstance(dex::TypeIndex idx) {
  if (UNLIKELY(idx.index_ >= dex_file_->GetHeader().type_ids_size_)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad type index " << idx.index_ << " (max "
                                      << dex_file_->GetHeader().type_ids_size_ << ")";
    return false;
  }
  // We don't need the actual class, just a pointer to the class name.
  const std::string_view descriptor = dex_file_->GetTypeDescriptorView(idx);
  if (UNLIKELY(descriptor[0] != 'L')) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "can't call new-instance on type '" << descriptor << "'";
    return false;
  } else if (UNLIKELY(descriptor == "Ljava/lang/Class;")) {
    // An unlikely new instance on Class is not allowed. Fall back to interpreter to ensure an
    // exception is thrown when this statement is executed (compiled code would not do that).
    Fail(VERIFY_ERROR_INSTANTIATION);
  }
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckNewArray(dex::TypeIndex idx) {
  if (UNLIKELY(idx.index_ >= dex_file_->GetHeader().type_ids_size_)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad type index " << idx.index_ << " (max "
                                      << dex_file_->GetHeader().type_ids_size_ << ")";
    return false;
  }
  int bracket_count = 0;
  const char* descriptor = dex_file_->GetTypeDescriptor(idx);
  const char* cp = descriptor;
  while (*cp++ == '[') {
    bracket_count++;
  }
  if (UNLIKELY(bracket_count == 0)) {
    /* The given class must be an array type. */
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "can't new-array class '" << descriptor << "' (not an array)";
    return false;
  } else if (UNLIKELY(bracket_count > 255)) {
    /* It is illegal to create an array of more than 255 dimensions. */
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "can't new-array class '" << descriptor << "' (exceeds limit)";
    return false;
  }
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckArrayData(uint32_t cur_offset) {
  const uint32_t insn_count = code_item_accessor_.InsnsSizeInCodeUnits();
  const uint16_t* insns = code_item_accessor_.Insns() + cur_offset;
  const uint16_t* array_data;
  int32_t array_data_offset;

  DCHECK_LT(cur_offset, insn_count);
  /* make sure the start of the array data table is in range */
  array_data_offset = insns[1] | (static_cast<int32_t>(insns[2]) << 16);
  if (UNLIKELY(static_cast<int32_t>(cur_offset) + array_data_offset < 0 ||
               cur_offset + array_data_offset + 2 >= insn_count)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid array data start: at " << cur_offset
                                      << ", data offset " << array_data_offset
                                      << ", count " << insn_count;
    return false;
  }
  /* offset to array data table is a relative branch-style offset */
  array_data = insns + array_data_offset;
  // Make sure the table is at an even dex pc, that is, 32-bit aligned.
  if (UNLIKELY(!IsAligned<4>(array_data))) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unaligned array data table: at " << cur_offset
                                      << ", data offset " << array_data_offset;
    return false;
  }
  // Make sure the array-data is marked as an opcode. This ensures that it was reached when
  // traversing the code item linearly. It is an approximation for a by-spec padding value.
  if (UNLIKELY(!GetInstructionFlags(cur_offset + array_data_offset).IsOpcode())) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "array data table at " << cur_offset
                                      << ", data offset " << array_data_offset
                                      << " not correctly visited, probably bad padding.";
    return false;
  }

  uint32_t value_width = array_data[1];
  uint32_t value_count = *reinterpret_cast<const uint32_t*>(&array_data[2]);
  uint32_t table_size = 4 + (value_width * value_count + 1) / 2;
  /* make sure the end of the switch is in range */
  if (UNLIKELY(cur_offset + array_data_offset + table_size > insn_count)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid array data end: at " << cur_offset
                                      << ", data offset " << array_data_offset << ", end "
                                      << cur_offset + array_data_offset + table_size
                                      << ", count " << insn_count;
    return false;
  }
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckBranchTarget(uint32_t cur_offset) {
  int32_t offset;
  bool isConditional, selfOkay;
  if (!GetBranchOffset(cur_offset, &offset, &isConditional, &selfOkay)) {
    return false;
  }
  if (UNLIKELY(!selfOkay && offset == 0)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "branch offset of zero not allowed at"
                                      << reinterpret_cast<void*>(cur_offset);
    return false;
  }
  // Check for 32-bit overflow. This isn't strictly necessary if we can depend on the runtime
  // to have identical "wrap-around" behavior, but it's unwise to depend on that.
  if (UNLIKELY(((int64_t) cur_offset + (int64_t) offset) != (int64_t) (cur_offset + offset))) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "branch target overflow "
                                      << reinterpret_cast<void*>(cur_offset) << " +" << offset;
    return false;
  }
  int32_t abs_offset = cur_offset + offset;
  if (UNLIKELY(abs_offset < 0 ||
               (uint32_t) abs_offset >= code_item_accessor_.InsnsSizeInCodeUnits()  ||
               !GetInstructionFlags(abs_offset).IsOpcode())) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid branch target " << offset << " (-> "
                                      << reinterpret_cast<void*>(abs_offset) << ") at "
                                      << reinterpret_cast<void*>(cur_offset);
    return false;
  }
  GetModifiableInstructionFlags(abs_offset).SetBranchTarget();
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::GetBranchOffset(uint32_t cur_offset,
                                                     int32_t* pOffset,
                                                     bool* pConditional,
                                                     bool* selfOkay) {
  const uint16_t* insns = code_item_accessor_.Insns() + cur_offset;
  *pConditional = false;
  *selfOkay = false;
  switch (*insns & 0xff) {
    case Instruction::GOTO:
      *pOffset = ((int16_t) *insns) >> 8;
      break;
    case Instruction::GOTO_32:
      *pOffset = insns[1] | (((uint32_t) insns[2]) << 16);
      *selfOkay = true;
      break;
    case Instruction::GOTO_16:
      *pOffset = (int16_t) insns[1];
      break;
    case Instruction::IF_EQ:
    case Instruction::IF_NE:
    case Instruction::IF_LT:
    case Instruction::IF_GE:
    case Instruction::IF_GT:
    case Instruction::IF_LE:
    case Instruction::IF_EQZ:
    case Instruction::IF_NEZ:
    case Instruction::IF_LTZ:
    case Instruction::IF_GEZ:
    case Instruction::IF_GTZ:
    case Instruction::IF_LEZ:
      *pOffset = (int16_t) insns[1];
      *pConditional = true;
      break;
    default:
      return false;
  }
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckSwitchTargets(uint32_t cur_offset) {
  const uint32_t insn_count = code_item_accessor_.InsnsSizeInCodeUnits();
  DCHECK_LT(cur_offset, insn_count);
  const uint16_t* insns = code_item_accessor_.Insns() + cur_offset;
  /* make sure the start of the switch is in range */
  int32_t switch_offset = insns[1] | (static_cast<int32_t>(insns[2]) << 16);
  if (UNLIKELY(static_cast<int32_t>(cur_offset) + switch_offset < 0 ||
               cur_offset + switch_offset + 2 > insn_count)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid switch start: at " << cur_offset
                                      << ", switch offset " << switch_offset
                                      << ", count " << insn_count;
    return false;
  }
  /* offset to switch table is a relative branch-style offset */
  const uint16_t* switch_insns = insns + switch_offset;
  // Make sure the table is at an even dex pc, that is, 32-bit aligned.
  if (UNLIKELY(!IsAligned<4>(switch_insns))) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unaligned switch table: at " << cur_offset
                                      << ", switch offset " << switch_offset;
    return false;
  }
  // Make sure the switch data is marked as an opcode. This ensures that it was reached when
  // traversing the code item linearly. It is an approximation for a by-spec padding value.
  if (UNLIKELY(!GetInstructionFlags(cur_offset + switch_offset).IsOpcode())) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "switch table at " << cur_offset
                                      << ", switch offset " << switch_offset
                                      << " not correctly visited, probably bad padding.";
    return false;
  }

  bool is_packed_switch = (*insns & 0xff) == Instruction::PACKED_SWITCH;

  uint32_t switch_count = switch_insns[1];
  int32_t targets_offset;
  uint16_t expected_signature;
  if (is_packed_switch) {
    /* 0=sig, 1=count, 2/3=firstKey */
    targets_offset = 4;
    expected_signature = Instruction::kPackedSwitchSignature;
  } else {
    /* 0=sig, 1=count, 2..count*2 = keys */
    targets_offset = 2 + 2 * switch_count;
    expected_signature = Instruction::kSparseSwitchSignature;
  }
  uint32_t table_size = targets_offset + switch_count * 2;
  if (UNLIKELY(switch_insns[0] != expected_signature)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << StringPrintf("wrong signature for switch table (%x, wanted %x)",
                        switch_insns[0], expected_signature);
    return false;
  }
  /* make sure the end of the switch is in range */
  if (UNLIKELY(cur_offset + switch_offset + table_size > (uint32_t) insn_count)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid switch end: at " << cur_offset
                                      << ", switch offset " << switch_offset
                                      << ", end " << (cur_offset + switch_offset + table_size)
                                      << ", count " << insn_count;
    return false;
  }

  constexpr int32_t keys_offset = 2;
  if (switch_count > 1) {
    if (is_packed_switch) {
      /* for a packed switch, verify that keys do not overflow int32 */
      int32_t first_key = switch_insns[keys_offset] | (switch_insns[keys_offset + 1] << 16);
      int32_t max_first_key =
          std::numeric_limits<int32_t>::max() - (static_cast<int32_t>(switch_count) - 1);
      if (UNLIKELY(first_key > max_first_key)) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid packed switch: first_key=" << first_key
                                          << ", switch_count=" << switch_count;
        return false;
      }
    } else {
      /* for a sparse switch, verify the keys are in ascending order */
      int32_t last_key = switch_insns[keys_offset] | (switch_insns[keys_offset + 1] << 16);
      for (uint32_t targ = 1; targ < switch_count; targ++) {
        int32_t key =
            static_cast<int32_t>(switch_insns[keys_offset + targ * 2]) |
            static_cast<int32_t>(switch_insns[keys_offset + targ * 2 + 1] << 16);
        if (UNLIKELY(key <= last_key)) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid sparse switch: last key=" << last_key
                                            << ", this=" << key;
          return false;
        }
        last_key = key;
      }
    }
  }
  /* verify each switch target */
  for (uint32_t targ = 0; targ < switch_count; targ++) {
    int32_t offset = static_cast<int32_t>(switch_insns[targets_offset + targ * 2]) |
                     static_cast<int32_t>(switch_insns[targets_offset + targ * 2 + 1] << 16);
    int32_t abs_offset = cur_offset + offset;
    if (UNLIKELY(abs_offset < 0 ||
                 abs_offset >= static_cast<int32_t>(insn_count) ||
                 !GetInstructionFlags(abs_offset).IsOpcode())) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid switch target " << offset
                                        << " (-> " << reinterpret_cast<void*>(abs_offset) << ") at "
                                        << reinterpret_cast<void*>(cur_offset)
                                        << "[" << targ << "]";
      return false;
    }
    GetModifiableInstructionFlags(abs_offset).SetBranchTarget();
  }
  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::VerifyCodeFlow() {
  const uint16_t registers_size = code_item_accessor_.RegistersSize();

  /* Create and initialize table holding register status */
  reg_table_.Init(insn_flags_.get(),
                  code_item_accessor_.InsnsSizeInCodeUnits(),
                  registers_size,
                  allocator_,
                  GetRegTypeCache(),
                  interesting_dex_pc_);

  work_line_.reset(RegisterLine::Create(registers_size, allocator_, GetRegTypeCache()));
  saved_line_.reset(RegisterLine::Create(registers_size, allocator_, GetRegTypeCache()));

  /* Initialize register types of method arguments. */
  if (!SetTypesFromSignature()) {
    DCHECK_NE(failures_.size(), 0U);
    std::string prepend("Bad signature in ");
    prepend += dex_file_->PrettyMethod(dex_method_idx_);
    PrependToLastFailMessage(prepend);
    return false;
  }
  // We may have a runtime failure here, clear.
  flags_.have_pending_runtime_throw_failure_ = false;

  /* Perform code flow verification. */
  bool res = LIKELY(monitor_enter_dex_pcs_ == nullptr)
                 ? CodeFlowVerifyMethod</*kMonitorDexPCs=*/ false>()
                 : CodeFlowVerifyMethod</*kMonitorDexPCs=*/ true>();
  if (UNLIKELY(!res)) {
    DCHECK_NE(failures_.size(), 0U);
    return false;
  }
  return true;
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::Dump(VariableIndentationOutputStream* vios) {
  if (!code_item_accessor_.HasCodeItem()) {
    vios->Stream() << "Native method\n";
    return;
  }
  {
    vios->Stream() << "Register Types:\n";
    ScopedIndentation indent1(vios);
    reg_types_.Dump(vios->Stream());
  }
  vios->Stream() << "Dumping instructions and register lines:\n";
  ScopedIndentation indent1(vios);

  for (const DexInstructionPcPair& inst : code_item_accessor_) {
    const size_t dex_pc = inst.DexPc();

    // Might be asked to dump before the table is initialized.
    if (reg_table_.IsInitialized()) {
      RegisterLine* reg_line = reg_table_.GetLine(dex_pc);
      if (reg_line != nullptr) {
        vios->Stream() << reg_line->Dump(this) << "\n";
      }
    }

    vios->Stream()
        << StringPrintf("0x%04zx", dex_pc) << ": " << GetInstructionFlags(dex_pc).ToString() << " ";
    const bool kDumpHexOfInstruction = false;
    if (kDumpHexOfInstruction) {
      vios->Stream() << inst->DumpHex(5) << " ";
    }
    vios->Stream() << inst->DumpString(dex_file_) << "\n";
  }
}

static bool IsPrimitiveDescriptor(char descriptor) {
  switch (descriptor) {
    case 'I':
    case 'C':
    case 'S':
    case 'B':
    case 'Z':
    case 'F':
    case 'D':
    case 'J':
      return true;
    default:
      return false;
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::SetTypesFromSignature() {
  RegisterLine* reg_line = reg_table_.GetLine(0);

  // Should have been verified earlier.
  DCHECK_GE(code_item_accessor_.RegistersSize(), code_item_accessor_.InsSize());

  uint32_t arg_start = code_item_accessor_.RegistersSize() - code_item_accessor_.InsSize();
  size_t expected_args = code_item_accessor_.InsSize();   /* long/double count as two */

  // Include the "this" pointer.
  size_t cur_arg = 0;
  if (!IsStatic()) {
    if (expected_args == 0) {
      // Expect at least a receiver.
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected 0 args, but method is not static";
      return false;
    }

    // If this is a constructor for a class other than java.lang.Object, mark the first ("this")
    // argument as uninitialized. This restricts field access until the superclass constructor is
    // called.
    const RegType& declaring_class = GetDeclaringClass();
    if (IsConstructor()) {
      if (declaring_class.IsJavaLangObject()) {
        // "this" is implicitly initialized.
        reg_line->SetThisInitialized();
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, declaring_class);
      } else {
        reg_line->SetRegisterType<LockOp::kClear>(
            arg_start + cur_arg,
            reg_types_.UninitializedThisArgument(declaring_class));
      }
    } else {
      reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, declaring_class);
    }
    cur_arg++;
  }

  const dex::ProtoId& proto_id =
      dex_file_->GetMethodPrototype(dex_file_->GetMethodId(dex_method_idx_));
  DexFileParameterIterator iterator(*dex_file_, proto_id);

  for (; iterator.HasNext(); iterator.Next()) {
    const char* descriptor = iterator.GetDescriptor();
    if (descriptor == nullptr) {
      LOG(FATAL) << "Null descriptor";
    }
    if (cur_arg >= expected_args) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected " << expected_args
                                        << " args, found more (" << descriptor << ")";
      return false;
    }
    switch (descriptor[0]) {
      case 'L':
      case '[':
        // We assume that reference arguments are initialized. The only way it could be otherwise
        // (assuming the caller was verified) is if the current method is <init>, but in that case
        // it's effectively considered initialized the instant we reach here (in the sense that we
        // can return without doing anything or call virtual methods).
        {
          // Note: don't check access. No error would be thrown for declaring or passing an
          //       inaccessible class. Only actual accesses to fields or methods will.
          const RegType& reg_type = ResolveClass<CheckAccess::kNo>(iterator.GetTypeIdx());
          if (!reg_type.IsNonZeroReferenceTypes()) {
            DCHECK(HasFailures());
            return false;
          }
          reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_type);
        }
        break;
      case 'Z':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Boolean());
        break;
      case 'C':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Char());
        break;
      case 'B':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Byte());
        break;
      case 'I':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Integer());
        break;
      case 'S':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Short());
        break;
      case 'F':
        reg_line->SetRegisterType<LockOp::kClear>(arg_start + cur_arg, reg_types_.Float());
        break;
      case 'J':
      case 'D': {
        if (cur_arg + 1 >= expected_args) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected " << expected_args
              << " args, found more (" << descriptor << ")";
          return false;
        }

        const RegType* lo_half;
        const RegType* hi_half;
        if (descriptor[0] == 'J') {
          lo_half = &reg_types_.LongLo();
          hi_half = &reg_types_.LongHi();
        } else {
          lo_half = &reg_types_.DoubleLo();
          hi_half = &reg_types_.DoubleHi();
        }
        reg_line->SetRegisterTypeWide(arg_start + cur_arg, *lo_half, *hi_half);
        cur_arg++;
        break;
      }
      default:
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected signature type char '"
                                          << descriptor << "'";
        return false;
    }
    cur_arg++;
  }
  if (cur_arg != expected_args) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected " << expected_args
                                      << " arguments, found " << cur_arg;
    return false;
  }
  const char* descriptor = dex_file_->GetReturnTypeDescriptor(proto_id);
  // Validate return type. We don't do the type lookup; just want to make sure that it has the right
  // format. Only major difference from the method argument format is that 'V' is supported.
  bool result;
  if (IsPrimitiveDescriptor(descriptor[0]) || descriptor[0] == 'V') {
    result = descriptor[1] == '\0';
  } else if (descriptor[0] == '[') {  // single/multi-dimensional array of object/primitive
    size_t i = 0;
    do {
      i++;
    } while (descriptor[i] == '[');  // process leading [
    if (descriptor[i] == 'L') {  // object array
      do {
        i++;  // find closing ;
      } while (descriptor[i] != ';' && descriptor[i] != '\0');
      result = descriptor[i] == ';';
    } else {  // primitive array
      result = IsPrimitiveDescriptor(descriptor[i]) && descriptor[i + 1] == '\0';
    }
  } else if (descriptor[0] == 'L') {
    // could be more thorough here, but shouldn't be required
    size_t i = 0;
    do {
      i++;
    } while (descriptor[i] != ';' && descriptor[i] != '\0');
    result = descriptor[i] == ';';
  } else {
    result = false;
  }
  if (!result) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected char in return type descriptor '"
                                      << descriptor << "'";
  }
  return result;
}

COLD_ATTR
void HandleMonitorDexPcsWorkLine(
    std::vector<::art::verifier::MethodVerifier::DexLockInfo>* monitor_enter_dex_pcs,
    RegisterLine* work_line) {
  monitor_enter_dex_pcs->clear();  // The new work line is more accurate than the previous one.

  std::map<uint32_t, ::art::verifier::MethodVerifier::DexLockInfo> depth_to_lock_info;
  auto collector = [&](uint32_t dex_reg, uint32_t depth) {
    auto insert_pair = depth_to_lock_info.emplace(
        depth, ::art::verifier::MethodVerifier::DexLockInfo(depth));
    auto it = insert_pair.first;
    auto set_insert_pair = it->second.dex_registers.insert(dex_reg);
    DCHECK(set_insert_pair.second);
  };
  work_line->IterateRegToLockDepths(collector);
  for (auto& pair : depth_to_lock_info) {
    monitor_enter_dex_pcs->push_back(pair.second);
    // Map depth to dex PC.
    monitor_enter_dex_pcs->back().dex_pc = work_line->GetMonitorEnterDexPc(pair.second.dex_pc);
  }
}

template <bool kVerifierDebug>
template <bool kMonitorDexPCs>
bool MethodVerifier<kVerifierDebug>::CodeFlowVerifyMethod() {
  const uint16_t* insns = code_item_accessor_.Insns();
  const uint32_t insns_size = code_item_accessor_.InsnsSizeInCodeUnits();

  /* Begin by marking the first instruction as "changed". */
  GetModifiableInstructionFlags(0).SetChanged();
  uint32_t start_guess = 0;

  /* Continue until no instructions are marked "changed". */
  while (true) {
    if (allow_thread_suspension_) {
      self_->AllowThreadSuspension();
    }
    // Find the first marked one. Use "start_guess" as a way to find one quickly.
    uint32_t insn_idx = start_guess;
    for (; insn_idx < insns_size; insn_idx++) {
      if (GetInstructionFlags(insn_idx).IsChanged())
        break;
    }
    if (insn_idx == insns_size) {
      if (start_guess != 0) {
        /* try again, starting from the top */
        start_guess = 0;
        continue;
      } else {
        /* all flags are clear */
        break;
      }
    }
    // We carry the working set of registers from instruction to instruction. If this address can
    // be the target of a branch (or throw) instruction, or if we're skipping around chasing
    // "changed" flags, we need to load the set of registers from the table.
    // Because we always prefer to continue on to the next instruction, we should never have a
    // situation where we have a stray "changed" flag set on an instruction that isn't a branch
    // target.
    work_insn_idx_ = insn_idx;
    if (GetInstructionFlags(insn_idx).IsBranchTarget()) {
      work_line_->CopyFromLine(reg_table_.GetLine(insn_idx));
    } else if (kIsDebugBuild) {
      /*
       * Consistency check: retrieve the stored register line (assuming
       * a full table) and make sure it actually matches.
       */
      RegisterLine* register_line = reg_table_.GetLine(insn_idx);
      if (register_line != nullptr) {
        if (work_line_->CompareLine(register_line) != 0) {
          Dump(LOG_STREAM(FATAL_WITHOUT_ABORT));
          LOG(FATAL_WITHOUT_ABORT) << info_messages_.str();
          LOG(FATAL) << "work_line diverged in " << dex_file_->PrettyMethod(dex_method_idx_)
                     << "@" << reinterpret_cast<void*>(work_insn_idx_) << "\n"
                     << " work_line=" << work_line_->Dump(this) << "\n"
                     << "  expected=" << register_line->Dump(this);
        }
      }
    }

    // If we're doing FindLocksAtDexPc, check whether we're at the dex pc we care about.
    // We want the state _before_ the instruction, for the case where the dex pc we're
    // interested in is itself a monitor-enter instruction (which is a likely place
    // for a thread to be suspended).
    if (kMonitorDexPCs && UNLIKELY(work_insn_idx_ == interesting_dex_pc_)) {
      HandleMonitorDexPcsWorkLine(monitor_enter_dex_pcs_, work_line_.get());
    }

    if (!CodeFlowVerifyInstruction(&start_guess)) {
      std::string prepend(dex_file_->PrettyMethod(dex_method_idx_));
      prepend += " failed to verify: ";
      PrependToLastFailMessage(prepend);
      return false;
    }
    /* Clear "changed" and mark as visited. */
    GetModifiableInstructionFlags(insn_idx).SetVisited();
    GetModifiableInstructionFlags(insn_idx).ClearChanged();
  }

  if (kVerifierDebug) {
    /*
     * Scan for dead code. There's nothing "evil" about dead code
     * (besides the wasted space), but it indicates a flaw somewhere
     * down the line, possibly in the verifier.
     *
     * If we've substituted "always throw" instructions into the stream,
     * we are almost certainly going to have some dead code.
     */
    int dead_start = -1;

    for (const DexInstructionPcPair& inst : code_item_accessor_) {
      const uint32_t insn_idx = inst.DexPc();
      /*
       * Switch-statement data doesn't get "visited" by scanner. It
       * may or may not be preceded by a padding NOP (for alignment).
       */
      if (insns[insn_idx] == Instruction::kPackedSwitchSignature ||
          insns[insn_idx] == Instruction::kSparseSwitchSignature ||
          insns[insn_idx] == Instruction::kArrayDataSignature ||
          (insns[insn_idx] == Instruction::NOP && (insn_idx + 1 < insns_size) &&
           (insns[insn_idx + 1] == Instruction::kPackedSwitchSignature ||
            insns[insn_idx + 1] == Instruction::kSparseSwitchSignature ||
            insns[insn_idx + 1] == Instruction::kArrayDataSignature))) {
        GetModifiableInstructionFlags(insn_idx).SetVisited();
      }

      if (!GetInstructionFlags(insn_idx).IsVisited()) {
        if (dead_start < 0) {
          dead_start = insn_idx;
        }
      } else if (dead_start >= 0) {
        LogVerifyInfo() << "dead code " << reinterpret_cast<void*>(dead_start)
                        << "-" << reinterpret_cast<void*>(insn_idx - 1);
        dead_start = -1;
      }
    }
    if (dead_start >= 0) {
      LogVerifyInfo()
          << "dead code " << reinterpret_cast<void*>(dead_start)
          << "-" << reinterpret_cast<void*>(code_item_accessor_.InsnsSizeInCodeUnits() - 1);
    }
    // To dump the state of the verify after a method, do something like:
    // if (dex_file_->PrettyMethod(dex_method_idx_) ==
    //     "boolean java.lang.String.equals(java.lang.Object)") {
    //   LOG(INFO) << info_messages_.str();
    // }
  }
  return true;
}

// Setup a register line for the given return instruction.
template <bool kVerifierDebug>
static void AdjustReturnLine(MethodVerifier<kVerifierDebug>* verifier,
                             const Instruction* ret_inst,
                             RegisterLine* line) {
  Instruction::Code opcode = ret_inst->Opcode();

  switch (opcode) {
    case Instruction::RETURN_VOID:
      if (verifier->IsInstanceConstructor()) {
        // Before we mark all regs as conflicts, check that we don't have an uninitialized this.
        line->CheckConstructorReturn(verifier);
      }
      line->MarkAllRegistersAsConflicts(verifier);
      break;

    case Instruction::RETURN:
    case Instruction::RETURN_OBJECT:
      line->MarkAllRegistersAsConflictsExcept(verifier, ret_inst->VRegA_11x());
      break;

    case Instruction::RETURN_WIDE:
      line->MarkAllRegistersAsConflictsExceptWide(verifier, ret_inst->VRegA_11x());
      break;

    default:
      LOG(FATAL) << "Unknown return opcode " << opcode;
      UNREACHABLE();
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CodeFlowVerifyInstruction(uint32_t* start_guess) {
  /*
   * Once we finish decoding the instruction, we need to figure out where
   * we can go from here. There are three possible ways to transfer
   * control to another statement:
   *
   * (1) Continue to the next instruction. Applies to all but
   *     unconditional branches, method returns, and exception throws.
   * (2) Branch to one or more possible locations. Applies to branches
   *     and switch statements.
   * (3) Exception handlers. Applies to any instruction that can
   *     throw an exception that is handled by an encompassing "try"
   *     block.
   *
   * We can also return, in which case there is no successor instruction
   * from this point.
   *
   * The behavior can be determined from the opcode flags.
   */
  const uint16_t* insns = code_item_accessor_.Insns() + work_insn_idx_;
  const Instruction* inst = Instruction::At(insns);
  int opcode_flags = Instruction::FlagsOf(inst->Opcode());

  int32_t branch_target = 0;
  bool just_set_result = false;
  if (kVerifierDebug) {
    // Generate processing back trace to debug verifier
    LogVerifyInfo() << "Processing " << inst->DumpString(dex_file_) << std::endl
                    << work_line_->Dump(this);
  }

  /*
   * Make a copy of the previous register state. If the instruction
   * can throw an exception, we will copy/merge this into the "catch"
   * address rather than work_line, because we don't want the result
   * from the "successful" code path (e.g. a check-cast that "improves"
   * a type) to be visible to the exception handler.
   */
  if (((opcode_flags & Instruction::kThrow) != 0 || IsCompatThrow(inst->Opcode())) &&
      CurrentInsnFlags()->IsInTry()) {
    saved_line_->CopyFromLine(work_line_.get());
  } else if (kIsDebugBuild) {
    saved_line_->FillWithGarbage();
  }
  // Per-instruction flag, should not be set here.
  DCHECK(!flags_.have_pending_runtime_throw_failure_);
  bool exc_handler_unreachable = false;


  // We need to ensure the work line is consistent while performing validation. When we spot a
  // peephole pattern we compute a new line for either the fallthrough instruction or the
  // branch target.
  RegisterLineArenaUniquePtr branch_line;
  RegisterLineArenaUniquePtr fallthrough_line;

  switch (inst->Opcode()) {
    case Instruction::NOP:
      /*
       * A "pure" NOP has no effect on anything. Data tables start with
       * a signature that looks like a NOP; if we see one of these in
       * the course of executing code then we have a problem.
       */
      if (inst->VRegA_10x() != 0) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "encountered data table in instruction stream";
      }
      break;

    case Instruction::MOVE:
      work_line_->CopyRegister1(this, inst->VRegA_12x(), inst->VRegB_12x(), kTypeCategory1nr);
      break;
    case Instruction::MOVE_FROM16:
      work_line_->CopyRegister1(this, inst->VRegA_22x(), inst->VRegB_22x(), kTypeCategory1nr);
      break;
    case Instruction::MOVE_16:
      work_line_->CopyRegister1(this, inst->VRegA_32x(), inst->VRegB_32x(), kTypeCategory1nr);
      break;
    case Instruction::MOVE_WIDE:
      work_line_->CopyRegister2(this, inst->VRegA_12x(), inst->VRegB_12x());
      break;
    case Instruction::MOVE_WIDE_FROM16:
      work_line_->CopyRegister2(this, inst->VRegA_22x(), inst->VRegB_22x());
      break;
    case Instruction::MOVE_WIDE_16:
      work_line_->CopyRegister2(this, inst->VRegA_32x(), inst->VRegB_32x());
      break;
    case Instruction::MOVE_OBJECT:
      work_line_->CopyRegister1(this, inst->VRegA_12x(), inst->VRegB_12x(), kTypeCategoryRef);
      break;
    case Instruction::MOVE_OBJECT_FROM16:
      work_line_->CopyRegister1(this, inst->VRegA_22x(), inst->VRegB_22x(), kTypeCategoryRef);
      break;
    case Instruction::MOVE_OBJECT_16:
      work_line_->CopyRegister1(this, inst->VRegA_32x(), inst->VRegB_32x(), kTypeCategoryRef);
      break;

    /*
     * The move-result instructions copy data out of a "pseudo-register"
     * with the results from the last method invocation. In practice we
     * might want to hold the result in an actual CPU register, so the
     * Dalvik spec requires that these only appear immediately after an
     * invoke or filled-new-array.
     *
     * These calls invalidate the "result" register. (This is now
     * redundant with the reset done below, but it can make the debug info
     * easier to read in some cases.)
     */
    case Instruction::MOVE_RESULT:
      work_line_->CopyResultRegister1(this, inst->VRegA_11x(), false);
      break;
    case Instruction::MOVE_RESULT_WIDE:
      work_line_->CopyResultRegister2(this, inst->VRegA_11x());
      break;
    case Instruction::MOVE_RESULT_OBJECT:
      work_line_->CopyResultRegister1(this, inst->VRegA_11x(), true);
      break;

    case Instruction::MOVE_EXCEPTION:
      if (!HandleMoveException(inst)) {
        exc_handler_unreachable = true;
      }
      break;

    case Instruction::RETURN_VOID:
      if (!IsInstanceConstructor() || work_line_->CheckConstructorReturn(this)) {
        if (!GetMethodReturnType().IsConflict()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "return-void not expected";
        }
      }
      break;
    case Instruction::RETURN:
      if (!IsInstanceConstructor() || work_line_->CheckConstructorReturn(this)) {
        /* check the method signature */
        const RegType& return_type = GetMethodReturnType();
        if (!return_type.IsCategory1Types()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected non-category 1 return type "
                                            << return_type;
        } else {
          // Compilers may generate synthetic functions that write byte values into boolean fields.
          // Also, it may use integer values for boolean, byte, short, and character return types.
          const uint32_t vregA = inst->VRegA_11x();
          const RegType& src_type = work_line_->GetRegisterType(this, vregA);
          bool use_src = ((return_type.IsBoolean() && src_type.IsByte()) ||
                          ((return_type.IsBoolean() || return_type.IsByte() ||
                           return_type.IsShort() || return_type.IsChar()) &&
                           src_type.IsInteger()));
          /* check the register contents */
          bool success =
              work_line_->VerifyRegisterType(this, vregA, use_src ? src_type : return_type);
          if (!success) {
            AppendToLastFailMessage(StringPrintf(" return-1nr on invalid register v%d", vregA));
          }
        }
      }
      break;
    case Instruction::RETURN_WIDE:
      if (!IsInstanceConstructor() || work_line_->CheckConstructorReturn(this)) {
        /* check the method signature */
        const RegType& return_type = GetMethodReturnType();
        if (!return_type.IsCategory2Types()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "return-wide not expected";
        } else {
          /* check the register contents */
          const uint32_t vregA = inst->VRegA_11x();
          bool success = work_line_->VerifyRegisterType(this, vregA, return_type);
          if (!success) {
            AppendToLastFailMessage(StringPrintf(" return-wide on invalid register v%d", vregA));
          }
        }
      }
      break;
    case Instruction::RETURN_OBJECT:
      if (!IsInstanceConstructor() || work_line_->CheckConstructorReturn(this)) {
        const RegType& return_type = GetMethodReturnType();
        if (!return_type.IsReferenceTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "return-object not expected";
        } else {
          /* return_type is the *expected* return type, not register value */
          DCHECK(!return_type.IsZeroOrNull());
          DCHECK(!return_type.IsUninitializedReference());
          const uint32_t vregA = inst->VRegA_11x();
          const RegType& reg_type = work_line_->GetRegisterType(this, vregA);
          // Disallow returning undefined, conflict & uninitialized values and verify that the
          // reference in vAA is an instance of the "return_type."
          if (reg_type.IsUndefined()) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "returning undefined register";
          } else if (reg_type.IsConflict()) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "returning register with conflict";
          } else if (reg_type.IsUninitializedTypes()) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "returning uninitialized object '"
                                              << reg_type << "'";
          } else if (!reg_type.IsReferenceTypes()) {
            // We really do expect a reference here.
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "return-object returns a non-reference type "
                                              << reg_type;
          } else if (!return_type.IsAssignableFrom(reg_type, this)) {
            if (reg_type.IsUnresolvedTypes() || return_type.IsUnresolvedTypes()) {
              Fail(VERIFY_ERROR_UNRESOLVED_TYPE_CHECK)
                  << " can't resolve returned type '" << return_type << "' or '" << reg_type << "'";
            } else {
              Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "returning '" << reg_type
                  << "', but expected from declaration '" << return_type << "'";
            }
          }
        }
      }
      break;

      /* could be boolean, int, float, or a null reference */
    case Instruction::CONST_4: {
      int32_t val = static_cast<int32_t>(inst->VRegB_11n() << 28) >> 28;
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_11n(), DetermineCat1Constant(val));
      break;
    }
    case Instruction::CONST_16: {
      int16_t val = static_cast<int16_t>(inst->VRegB_21s());
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_21s(), DetermineCat1Constant(val));
      break;
    }
    case Instruction::CONST: {
      int32_t val = inst->VRegB_31i();
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_31i(), DetermineCat1Constant(val));
      break;
    }
    case Instruction::CONST_HIGH16: {
      int32_t val = static_cast<int32_t>(inst->VRegB_21h() << 16);
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_21h(), DetermineCat1Constant(val));
      break;
    }
      /* could be long or double; resolved upon use */
    case Instruction::CONST_WIDE_16: {
      int64_t val = static_cast<int16_t>(inst->VRegB_21s());
      const RegType& lo = reg_types_.FromCat2ConstLo(static_cast<int32_t>(val), true);
      const RegType& hi = reg_types_.FromCat2ConstHi(static_cast<int32_t>(val >> 32), true);
      work_line_->SetRegisterTypeWide(inst->VRegA_21s(), lo, hi);
      break;
    }
    case Instruction::CONST_WIDE_32: {
      int64_t val = static_cast<int32_t>(inst->VRegB_31i());
      const RegType& lo = reg_types_.FromCat2ConstLo(static_cast<int32_t>(val), true);
      const RegType& hi = reg_types_.FromCat2ConstHi(static_cast<int32_t>(val >> 32), true);
      work_line_->SetRegisterTypeWide(inst->VRegA_31i(), lo, hi);
      break;
    }
    case Instruction::CONST_WIDE: {
      int64_t val = inst->VRegB_51l();
      const RegType& lo = reg_types_.FromCat2ConstLo(static_cast<int32_t>(val), true);
      const RegType& hi = reg_types_.FromCat2ConstHi(static_cast<int32_t>(val >> 32), true);
      work_line_->SetRegisterTypeWide(inst->VRegA_51l(), lo, hi);
      break;
    }
    case Instruction::CONST_WIDE_HIGH16: {
      int64_t val = static_cast<uint64_t>(inst->VRegB_21h()) << 48;
      const RegType& lo = reg_types_.FromCat2ConstLo(static_cast<int32_t>(val), true);
      const RegType& hi = reg_types_.FromCat2ConstHi(static_cast<int32_t>(val >> 32), true);
      work_line_->SetRegisterTypeWide(inst->VRegA_21h(), lo, hi);
      break;
    }
    case Instruction::CONST_STRING:
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_21c(), reg_types_.JavaLangString());
      break;
    case Instruction::CONST_STRING_JUMBO:
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_31c(), reg_types_.JavaLangString());
      break;
    case Instruction::CONST_CLASS: {
      // Get type from instruction if unresolved then we need an access check
      // TODO: check Compiler::CanAccessTypeWithoutChecks returns false when res_type is unresolved
      const RegType& res_type = ResolveClass<CheckAccess::kYes>(dex::TypeIndex(inst->VRegB_21c()));
      // Register holds class, ie its type is class, on error it will hold Conflict.
      work_line_->SetRegisterType<LockOp::kClear>(
          inst->VRegA_21c(),
          res_type.IsConflict() ? res_type : reg_types_.JavaLangClass());
      break;
    }
    case Instruction::CONST_METHOD_HANDLE:
      work_line_->SetRegisterType<LockOp::kClear>(
          inst->VRegA_21c(), reg_types_.JavaLangInvokeMethodHandle());
      break;
    case Instruction::CONST_METHOD_TYPE:
      work_line_->SetRegisterType<LockOp::kClear>(
          inst->VRegA_21c(), reg_types_.JavaLangInvokeMethodType());
      break;
    case Instruction::MONITOR_ENTER:
      work_line_->PushMonitor(this, inst->VRegA_11x(), work_insn_idx_);
      // Check whether the previous instruction is a move-object with vAA as a source, creating
      // untracked lock aliasing.
      if (0 != work_insn_idx_ && !GetInstructionFlags(work_insn_idx_).IsBranchTarget()) {
        uint32_t prev_idx = work_insn_idx_ - 1;
        while (0 != prev_idx && !GetInstructionFlags(prev_idx).IsOpcode()) {
          prev_idx--;
        }
        const Instruction& prev_inst = code_item_accessor_.InstructionAt(prev_idx);
        switch (prev_inst.Opcode()) {
          case Instruction::MOVE_OBJECT:
          case Instruction::MOVE_OBJECT_16:
          case Instruction::MOVE_OBJECT_FROM16:
            if (prev_inst.VRegB() == inst->VRegA_11x()) {
              // Redo the copy. This won't change the register types, but update the lock status
              // for the aliased register.
              work_line_->CopyRegister1(this,
                                        prev_inst.VRegA(),
                                        prev_inst.VRegB(),
                                        kTypeCategoryRef);
            }
            break;

          // Catch a case of register aliasing when two registers are linked to the same
          // java.lang.Class object via two consequent const-class instructions immediately
          // preceding monitor-enter called on one of those registers.
          case Instruction::CONST_CLASS: {
            // Get the second previous instruction.
            if (prev_idx == 0 || GetInstructionFlags(prev_idx).IsBranchTarget()) {
              break;
            }
            prev_idx--;
            while (0 != prev_idx && !GetInstructionFlags(prev_idx).IsOpcode()) {
              prev_idx--;
            }
            const Instruction& prev2_inst = code_item_accessor_.InstructionAt(prev_idx);

            // Match the pattern "const-class; const-class; monitor-enter;"
            if (prev2_inst.Opcode() != Instruction::CONST_CLASS) {
              break;
            }

            // Ensure both const-classes are called for the same type_idx.
            if (prev_inst.VRegB_21c() != prev2_inst.VRegB_21c()) {
              break;
            }

            // Update the lock status for the aliased register.
            if (prev_inst.VRegA() == inst->VRegA_11x()) {
              work_line_->CopyRegister1(this,
                                        prev2_inst.VRegA(),
                                        inst->VRegA_11x(),
                                        kTypeCategoryRef);
            } else if (prev2_inst.VRegA() == inst->VRegA_11x()) {
              work_line_->CopyRegister1(this,
                                        prev_inst.VRegA(),
                                        inst->VRegA_11x(),
                                        kTypeCategoryRef);
            }
            break;
          }

          default:  // Other instruction types ignored.
            break;
        }
      }
      break;
    case Instruction::MONITOR_EXIT:
      /*
       * monitor-exit instructions are odd. They can throw exceptions,
       * but when they do they act as if they succeeded and the PC is
       * pointing to the following instruction. (This behavior goes back
       * to the need to handle asynchronous exceptions, a now-deprecated
       * feature that Dalvik doesn't support.)
       *
       * In practice we don't need to worry about this. The only
       * exceptions that can be thrown from monitor-exit are for a
       * null reference and -exit without a matching -enter. If the
       * structured locking checks are working, the former would have
       * failed on the -enter instruction, and the latter is impossible.
       *
       * This is fortunate, because issue 3221411 prevents us from
       * chasing the "can throw" path when monitor verification is
       * enabled. If we can fully verify the locking we can ignore
       * some catch blocks (which will show up as "dead" code when
       * we skip them here); if we can't, then the code path could be
       * "live" so we still need to check it.
       */
      opcode_flags &= ~Instruction::kThrow;
      work_line_->PopMonitor(this, inst->VRegA_11x());
      break;
    case Instruction::CHECK_CAST:
    case Instruction::INSTANCE_OF: {
      /*
       * If this instruction succeeds, we will "downcast" register vA to the type in vB. (This
       * could be a "upcast" -- not expected, so we don't try to address it.)
       *
       * If it fails, an exception is thrown, which we deal with later by ignoring the update to
       * dec_insn.vA when branching to a handler.
       */
      const bool is_checkcast = (inst->Opcode() == Instruction::CHECK_CAST);
      const dex::TypeIndex type_idx((is_checkcast) ? inst->VRegB_21c() : inst->VRegC_22c());
      const RegType& res_type = ResolveClass<CheckAccess::kYes>(type_idx);
      if (res_type.IsConflict()) {
        // If this is a primitive type, fail HARD.
        ObjPtr<mirror::Class> klass = GetClassLinker()->LookupResolvedType(
            type_idx, dex_cache_.Get(), class_loader_.Get());
        if (klass != nullptr && klass->IsPrimitive()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "using primitive type "
              << dex_file_->GetTypeDescriptorView(type_idx) << " in instanceof in "
              << GetDeclaringClass();
          break;
        }

        DCHECK_NE(failures_.size(), 0U);
        if (!is_checkcast) {
          work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_22c(), reg_types_.Boolean());
        }
        break;  // bad class
      }
      // TODO: check Compiler::CanAccessTypeWithoutChecks returns false when res_type is unresolved
      uint32_t orig_type_reg = (is_checkcast) ? inst->VRegA_21c() : inst->VRegB_22c();
      const RegType& orig_type = work_line_->GetRegisterType(this, orig_type_reg);
      if (!res_type.IsNonZeroReferenceTypes()) {
        if (is_checkcast) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "check-cast on unexpected class " << res_type;
        } else {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "instance-of on unexpected class " << res_type;
        }
      } else if (!orig_type.IsReferenceTypes()) {
        if (is_checkcast) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "check-cast on non-reference in v" << orig_type_reg;
        } else {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "instance-of on non-reference in v" << orig_type_reg;
        }
      } else if (orig_type.IsUninitializedTypes()) {
        if (is_checkcast) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "check-cast on uninitialized reference in v"
                                            << orig_type_reg;
        } else {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "instance-of on uninitialized reference in v"
                                            << orig_type_reg;
        }
      } else {
        if (is_checkcast) {
          work_line_->SetRegisterType<LockOp::kKeep>(inst->VRegA_21c(), res_type);
        } else {
          work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_22c(), reg_types_.Boolean());
        }
      }
      break;
    }
    case Instruction::ARRAY_LENGTH: {
      const RegType& res_type = work_line_->GetRegisterType(this, inst->VRegB_12x());
      if (res_type.IsReferenceTypes()) {
        if (!res_type.IsArrayTypes() && !res_type.IsZeroOrNull()) {
          // ie not an array or null
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "array-length on non-array " << res_type;
        } else {
          work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_12x(), reg_types_.Integer());
        }
      } else {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "array-length on non-array " << res_type;
      }
      break;
    }
    case Instruction::NEW_INSTANCE: {
      const RegType& res_type = ResolveClass<CheckAccess::kYes>(dex::TypeIndex(inst->VRegB_21c()));
      if (res_type.IsConflict()) {
        DCHECK_NE(failures_.size(), 0U);
        break;  // bad class
      }
      // TODO: check Compiler::CanAccessTypeWithoutChecks returns false when res_type is unresolved
      // can't create an instance of an interface or abstract class */
      if (!res_type.IsInstantiableTypes()) {
        Fail(VERIFY_ERROR_INSTANTIATION)
            << "new-instance on primitive, interface or abstract class" << res_type;
        // Soft failure so carry on to set register type.
      }
      const RegType& uninit_type = reg_types_.Uninitialized(res_type, work_insn_idx_);
      // Any registers holding previous allocations from this address that have not yet been
      // initialized must be marked invalid.
      work_line_->MarkUninitRefsAsInvalid(this, uninit_type);
      // add the new uninitialized reference to the register state
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_21c(), uninit_type);
      break;
    }
    case Instruction::NEW_ARRAY:
      VerifyNewArray(inst, false, false);
      break;
    case Instruction::FILLED_NEW_ARRAY:
      VerifyNewArray(inst, true, false);
      just_set_result = true;  // Filled new array sets result register
      break;
    case Instruction::FILLED_NEW_ARRAY_RANGE:
      VerifyNewArray(inst, true, true);
      just_set_result = true;  // Filled new array range sets result register
      break;
    case Instruction::CMPL_FLOAT:
    case Instruction::CMPG_FLOAT:
      if (!work_line_->VerifyRegisterType(this, inst->VRegB_23x(), reg_types_.Float())) {
        break;
      }
      if (!work_line_->VerifyRegisterType(this, inst->VRegC_23x(), reg_types_.Float())) {
        break;
      }
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), reg_types_.Integer());
      break;
    case Instruction::CMPL_DOUBLE:
    case Instruction::CMPG_DOUBLE:
      if (!work_line_->VerifyRegisterTypeWide(this, inst->VRegB_23x(), reg_types_.DoubleLo(),
                                              reg_types_.DoubleHi())) {
        break;
      }
      if (!work_line_->VerifyRegisterTypeWide(this, inst->VRegC_23x(), reg_types_.DoubleLo(),
                                              reg_types_.DoubleHi())) {
        break;
      }
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), reg_types_.Integer());
      break;
    case Instruction::CMP_LONG:
      if (!work_line_->VerifyRegisterTypeWide(this, inst->VRegB_23x(), reg_types_.LongLo(),
                                              reg_types_.LongHi())) {
        break;
      }
      if (!work_line_->VerifyRegisterTypeWide(this, inst->VRegC_23x(), reg_types_.LongLo(),
                                              reg_types_.LongHi())) {
        break;
      }
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), reg_types_.Integer());
      break;
    case Instruction::THROW: {
      const RegType& res_type = work_line_->GetRegisterType(this, inst->VRegA_11x());
      if (!reg_types_.JavaLangThrowable().IsAssignableFrom(res_type, this)) {
        if (res_type.IsUninitializedTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "thrown exception not initialized";
        } else if (!res_type.IsReferenceTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "thrown value of non-reference type " << res_type;
        } else {
          Fail(res_type.IsUnresolvedTypes()
                  ? VERIFY_ERROR_UNRESOLVED_TYPE_CHECK : VERIFY_ERROR_BAD_CLASS_HARD)
                << "thrown class " << res_type << " not instanceof Throwable";
        }
      }
      break;
    }
    case Instruction::GOTO:
    case Instruction::GOTO_16:
    case Instruction::GOTO_32:
      /* no effect on or use of registers */
      break;

    case Instruction::PACKED_SWITCH:
    case Instruction::SPARSE_SWITCH:
      /* verify that vAA is an integer, or can be converted to one */
      work_line_->VerifyRegisterType(this, inst->VRegA_31t(), reg_types_.Integer());
      break;

    case Instruction::FILL_ARRAY_DATA: {
      /* Similar to the verification done for APUT */
      const RegType& array_type = work_line_->GetRegisterType(this, inst->VRegA_31t());
      /* array_type can be null if the reg type is Zero */
      if (!array_type.IsZeroOrNull()) {
        if (!array_type.IsArrayTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid fill-array-data with array type "
                                            << array_type;
        } else if (array_type.IsUnresolvedTypes()) {
          // If it's an unresolved array type, it must be non-primitive.
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid fill-array-data for array of type "
                                            << array_type;
        } else {
          const RegType& component_type = reg_types_.GetComponentType(array_type, class_loader_);
          DCHECK(!component_type.IsConflict());
          if (component_type.IsNonZeroReferenceTypes()) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid fill-array-data with component type "
                                              << component_type;
          } else {
            // Now verify if the element width in the table matches the element width declared in
            // the array
            const uint16_t* array_data =
                insns + (insns[1] | (static_cast<int32_t>(insns[2]) << 16));
            if (array_data[0] != Instruction::kArrayDataSignature) {
              Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid magic for array-data";
            } else {
              size_t elem_width = Primitive::ComponentSize(component_type.GetPrimitiveType());
              // Since we don't compress the data in Dex, expect to see equal width of data stored
              // in the table and expected from the array class.
              if (array_data[1] != elem_width) {
                Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "array-data size mismatch (" << array_data[1]
                                                  << " vs " << elem_width << ")";
              }
            }
          }
        }
      }
      break;
    }
    case Instruction::IF_EQ:
    case Instruction::IF_NE: {
      const RegType& reg_type1 = work_line_->GetRegisterType(this, inst->VRegA_22t());
      const RegType& reg_type2 = work_line_->GetRegisterType(this, inst->VRegB_22t());
      bool mismatch = false;
      if (reg_type1.IsZeroOrNull()) {  // zero then integral or reference expected
        mismatch = !reg_type2.IsReferenceTypes() && !reg_type2.IsIntegralTypes();
      } else if (reg_type1.IsReferenceTypes()) {  // both references?
        mismatch = !reg_type2.IsReferenceTypes();
      } else {  // both integral?
        mismatch = !reg_type1.IsIntegralTypes() || !reg_type2.IsIntegralTypes();
      }
      if (mismatch) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "args to if-eq/if-ne (" << reg_type1 << ","
                                          << reg_type2 << ") must both be references or integral";
      }
      break;
    }
    case Instruction::IF_LT:
    case Instruction::IF_GE:
    case Instruction::IF_GT:
    case Instruction::IF_LE: {
      const RegType& reg_type1 = work_line_->GetRegisterType(this, inst->VRegA_22t());
      const RegType& reg_type2 = work_line_->GetRegisterType(this, inst->VRegB_22t());
      if (!reg_type1.IsIntegralTypes() || !reg_type2.IsIntegralTypes()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "args to 'if' (" << reg_type1 << ","
                                          << reg_type2 << ") must be integral";
      }
      break;
    }
    case Instruction::IF_EQZ:
    case Instruction::IF_NEZ: {
      const RegType& reg_type = work_line_->GetRegisterType(this, inst->VRegA_21t());
      if (!reg_type.IsReferenceTypes() && !reg_type.IsIntegralTypes()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "type " << reg_type
                                          << " unexpected as arg to if-eqz/if-nez";
      }

      // Find previous instruction - its existence is a precondition to peephole optimization.
      if (UNLIKELY(0 == work_insn_idx_)) {
        break;
      }
      uint32_t instance_of_idx = work_insn_idx_ - 1;
      while (0 != instance_of_idx && !GetInstructionFlags(instance_of_idx).IsOpcode()) {
        instance_of_idx--;
      }
      // Dex index 0 must be an opcode.
      DCHECK(GetInstructionFlags(instance_of_idx).IsOpcode());

      const Instruction& instance_of_inst = code_item_accessor_.InstructionAt(instance_of_idx);

      /* Check for peep-hole pattern of:
       *    ...;
       *    instance-of vX, vY, T;
       *    ifXXX vX, label ;
       *    ...;
       * label:
       *    ...;
       * and sharpen the type of vY to be type T.
       * Note, this pattern can't be if:
       *  - if there are other branches to this branch,
       *  - when vX == vY.
       */
      if (!CurrentInsnFlags()->IsBranchTarget() &&
          (Instruction::INSTANCE_OF == instance_of_inst.Opcode()) &&
          (inst->VRegA_21t() == instance_of_inst.VRegA_22c()) &&
          (instance_of_inst.VRegA_22c() != instance_of_inst.VRegB_22c())) {
        // Check the type of the instance-of is different than that of registers type, as if they
        // are the same there is no work to be done here. Check that the conversion is not to or
        // from an unresolved type as type information is imprecise. If the instance-of is to an
        // interface then ignore the type information as interfaces can only be treated as Objects
        // and we don't want to disallow field and other operations on the object. If the value
        // being instance-of checked against is known null (zero) then allow the optimization as
        // we didn't have type information. If the merge of the instance-of type with the original
        // type is assignable to the original then allow optimization. This check is performed to
        // ensure that subsequent merges don't lose type information - such as becoming an
        // interface from a class that would lose information relevant to field checks.
        //
        // Note: do not do an access check. This may mark this with a runtime throw that actually
        //       happens at the instanceof, not the branch (and branches aren't flagged to throw).
        const RegType& orig_type = work_line_->GetRegisterType(this, instance_of_inst.VRegB_22c());
        const RegType& cast_type = ResolveClass<CheckAccess::kNo>(
            dex::TypeIndex(instance_of_inst.VRegC_22c()));

        if (!orig_type.Equals(cast_type) &&
            !cast_type.IsUnresolvedTypes() && !orig_type.IsUnresolvedTypes() &&
            cast_type.HasClass() &&             // Could be conflict type, make sure it has a class.
            !cast_type.GetClass()->IsInterface() &&
            !orig_type.IsZeroOrNull() &&
            orig_type.IsStrictlyAssignableFrom(
                cast_type.Merge(orig_type, &reg_types_, this), this)) {
          RegisterLine* update_line = RegisterLine::Create(code_item_accessor_.RegistersSize(),
                                                           allocator_,
                                                           GetRegTypeCache());
          if (inst->Opcode() == Instruction::IF_EQZ) {
            fallthrough_line.reset(update_line);
          } else {
            branch_line.reset(update_line);
          }
          update_line->CopyFromLine(work_line_.get());
          update_line->SetRegisterType<LockOp::kKeep>(instance_of_inst.VRegB_22c(), cast_type);
          if (!GetInstructionFlags(instance_of_idx).IsBranchTarget() && 0 != instance_of_idx) {
            // See if instance-of was preceded by a move-object operation, common due to the small
            // register encoding space of instance-of, and propagate type information to the source
            // of the move-object.
            // Note: this is only valid if the move source was not clobbered.
            uint32_t move_idx = instance_of_idx - 1;
            while (0 != move_idx && !GetInstructionFlags(move_idx).IsOpcode()) {
              move_idx--;
            }
            DCHECK(GetInstructionFlags(move_idx).IsOpcode());
            auto maybe_update_fn = [&instance_of_inst, update_line, &cast_type](
                uint16_t move_src,
                uint16_t move_trg)
                REQUIRES_SHARED(Locks::mutator_lock_) {
              if (move_trg == instance_of_inst.VRegB_22c() &&
                  move_src != instance_of_inst.VRegA_22c()) {
                update_line->SetRegisterType<LockOp::kKeep>(move_src, cast_type);
              }
            };
            const Instruction& move_inst = code_item_accessor_.InstructionAt(move_idx);
            switch (move_inst.Opcode()) {
              case Instruction::MOVE_OBJECT:
                maybe_update_fn(move_inst.VRegB_12x(), move_inst.VRegA_12x());
                break;
              case Instruction::MOVE_OBJECT_FROM16:
                maybe_update_fn(move_inst.VRegB_22x(), move_inst.VRegA_22x());
                break;
              case Instruction::MOVE_OBJECT_16:
                maybe_update_fn(move_inst.VRegB_32x(), move_inst.VRegA_32x());
                break;
              default:
                break;
            }
          }
        }
      }

      break;
    }
    case Instruction::IF_LTZ:
    case Instruction::IF_GEZ:
    case Instruction::IF_GTZ:
    case Instruction::IF_LEZ: {
      const RegType& reg_type = work_line_->GetRegisterType(this, inst->VRegA_21t());
      if (!reg_type.IsIntegralTypes()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "type " << reg_type
                                          << " unexpected as arg to if-ltz/if-gez/if-gtz/if-lez";
      }
      break;
    }
    case Instruction::AGET_BOOLEAN:
      VerifyAGet(inst, reg_types_.Boolean(), true);
      break;
    case Instruction::AGET_BYTE:
      VerifyAGet(inst, reg_types_.Byte(), true);
      break;
    case Instruction::AGET_CHAR:
      VerifyAGet(inst, reg_types_.Char(), true);
      break;
    case Instruction::AGET_SHORT:
      VerifyAGet(inst, reg_types_.Short(), true);
      break;
    case Instruction::AGET:
      VerifyAGet(inst, reg_types_.Integer(), true);
      break;
    case Instruction::AGET_WIDE:
      VerifyAGet(inst, reg_types_.LongLo(), true);
      break;
    case Instruction::AGET_OBJECT:
      VerifyAGet(inst, reg_types_.JavaLangObject(false), false);
      break;

    case Instruction::APUT_BOOLEAN:
      VerifyAPut(inst, reg_types_.Boolean(), true);
      break;
    case Instruction::APUT_BYTE:
      VerifyAPut(inst, reg_types_.Byte(), true);
      break;
    case Instruction::APUT_CHAR:
      VerifyAPut(inst, reg_types_.Char(), true);
      break;
    case Instruction::APUT_SHORT:
      VerifyAPut(inst, reg_types_.Short(), true);
      break;
    case Instruction::APUT:
      VerifyAPut(inst, reg_types_.Integer(), true);
      break;
    case Instruction::APUT_WIDE:
      VerifyAPut(inst, reg_types_.LongLo(), true);
      break;
    case Instruction::APUT_OBJECT:
      VerifyAPut(inst, reg_types_.JavaLangObject(false), false);
      break;

    case Instruction::IGET_BOOLEAN:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Boolean(), true, false);
      break;
    case Instruction::IGET_BYTE:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Byte(), true, false);
      break;
    case Instruction::IGET_CHAR:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Char(), true, false);
      break;
    case Instruction::IGET_SHORT:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Short(), true, false);
      break;
    case Instruction::IGET:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Integer(), true, false);
      break;
    case Instruction::IGET_WIDE:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.LongLo(), true, false);
      break;
    case Instruction::IGET_OBJECT:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.JavaLangObject(false), false,
                                                    false);
      break;

    case Instruction::IPUT_BOOLEAN:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Boolean(), true, false);
      break;
    case Instruction::IPUT_BYTE:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Byte(), true, false);
      break;
    case Instruction::IPUT_CHAR:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Char(), true, false);
      break;
    case Instruction::IPUT_SHORT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Short(), true, false);
      break;
    case Instruction::IPUT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Integer(), true, false);
      break;
    case Instruction::IPUT_WIDE:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.LongLo(), true, false);
      break;
    case Instruction::IPUT_OBJECT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.JavaLangObject(false), false,
                                                    false);
      break;

    case Instruction::SGET_BOOLEAN:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Boolean(), true, true);
      break;
    case Instruction::SGET_BYTE:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Byte(), true, true);
      break;
    case Instruction::SGET_CHAR:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Char(), true, true);
      break;
    case Instruction::SGET_SHORT:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Short(), true, true);
      break;
    case Instruction::SGET:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.Integer(), true, true);
      break;
    case Instruction::SGET_WIDE:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.LongLo(), true, true);
      break;
    case Instruction::SGET_OBJECT:
      VerifyISFieldAccess<FieldAccessType::kAccGet>(inst, reg_types_.JavaLangObject(false), false,
                                                    true);
      break;

    case Instruction::SPUT_BOOLEAN:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Boolean(), true, true);
      break;
    case Instruction::SPUT_BYTE:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Byte(), true, true);
      break;
    case Instruction::SPUT_CHAR:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Char(), true, true);
      break;
    case Instruction::SPUT_SHORT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Short(), true, true);
      break;
    case Instruction::SPUT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.Integer(), true, true);
      break;
    case Instruction::SPUT_WIDE:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.LongLo(), true, true);
      break;
    case Instruction::SPUT_OBJECT:
      VerifyISFieldAccess<FieldAccessType::kAccPut>(inst, reg_types_.JavaLangObject(false), false,
                                                    true);
      break;

    case Instruction::INVOKE_VIRTUAL:
    case Instruction::INVOKE_VIRTUAL_RANGE:
    case Instruction::INVOKE_SUPER:
    case Instruction::INVOKE_SUPER_RANGE: {
      bool is_range = (inst->Opcode() == Instruction::INVOKE_VIRTUAL_RANGE ||
                       inst->Opcode() == Instruction::INVOKE_SUPER_RANGE);
      bool is_super = (inst->Opcode() == Instruction::INVOKE_SUPER ||
                       inst->Opcode() == Instruction::INVOKE_SUPER_RANGE);
      MethodType type = is_super ? METHOD_SUPER : METHOD_VIRTUAL;
      ArtMethod* called_method = VerifyInvocationArgs(inst, type, is_range);
      const RegType* return_type = nullptr;
      if (called_method != nullptr) {
        ObjPtr<mirror::Class> return_type_class = CanLoadClasses()
            ? called_method->ResolveReturnType()
            : called_method->LookupResolvedReturnType();
        if (return_type_class != nullptr) {
          return_type = &FromClass(called_method->GetReturnTypeDescriptor(),
                                   return_type_class,
                                   return_type_class->CannotBeAssignedFromOtherTypes());
        } else {
          DCHECK_IMPLIES(CanLoadClasses(), self_->IsExceptionPending());
          self_->ClearException();
        }
      }
      if (return_type == nullptr) {
        uint32_t method_idx = GetMethodIdxOfInvoke(inst);
        const dex::MethodId& method_id = dex_file_->GetMethodId(method_idx);
        dex::TypeIndex return_type_idx =
            dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
        const char* descriptor = dex_file_->GetTypeDescriptor(return_type_idx);
        return_type = &reg_types_.FromDescriptor(class_loader_, descriptor);
      }
      if (!return_type->IsLowHalf()) {
        work_line_->SetResultRegisterType(this, *return_type);
      } else {
        work_line_->SetResultRegisterTypeWide(*return_type, return_type->HighHalf(&reg_types_));
      }
      just_set_result = true;
      break;
    }
    case Instruction::INVOKE_DIRECT:
    case Instruction::INVOKE_DIRECT_RANGE: {
      bool is_range = (inst->Opcode() == Instruction::INVOKE_DIRECT_RANGE);
      ArtMethod* called_method = VerifyInvocationArgs(inst, METHOD_DIRECT, is_range);
      const char* return_type_descriptor;
      bool is_constructor;
      const RegType* return_type = nullptr;
      if (called_method == nullptr) {
        uint32_t method_idx = (is_range) ? inst->VRegB_3rc() : inst->VRegB_35c();
        const dex::MethodId& method_id = dex_file_->GetMethodId(method_idx);
        is_constructor = dex_file_->GetStringView(method_id.name_idx_) == "<init>";
        dex::TypeIndex return_type_idx =
            dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
        return_type_descriptor =  dex_file_->GetTypeDescriptor(return_type_idx);
      } else {
        is_constructor = called_method->IsConstructor();
        return_type_descriptor = called_method->GetReturnTypeDescriptor();
        ObjPtr<mirror::Class> return_type_class = CanLoadClasses()
            ? called_method->ResolveReturnType()
            : called_method->LookupResolvedReturnType();
        if (return_type_class != nullptr) {
          return_type = &FromClass(return_type_descriptor,
                                   return_type_class,
                                   return_type_class->CannotBeAssignedFromOtherTypes());
        } else {
          DCHECK_IMPLIES(CanLoadClasses(), self_->IsExceptionPending());
          self_->ClearException();
        }
      }
      if (is_constructor) {
        /*
         * Some additional checks when calling a constructor. We know from the invocation arg check
         * that the "this" argument is an instance of called_method->klass. Now we further restrict
         * that to require that called_method->klass is the same as this->klass or this->super,
         * allowing the latter only if the "this" argument is the same as the "this" argument to
         * this method (which implies that we're in a constructor ourselves).
         */
        const RegType& this_type = work_line_->GetInvocationThis(this, inst);
        if (this_type.IsConflict())  // failure.
          break;

        /* no null refs allowed (?) */
        if (this_type.IsZeroOrNull()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unable to initialize null ref";
          break;
        }

        /* must be in same class or in superclass */
        // const RegType& this_super_klass = this_type.GetSuperClass(&reg_types_);
        // TODO: re-enable constructor type verification
        // if (this_super_klass.IsConflict()) {
          // Unknown super class, fail so we re-check at runtime.
          // Fail(VERIFY_ERROR_BAD_CLASS_SOFT) << "super class unknown for '" << this_type << "'";
          // break;
        // }

        /* arg must be an uninitialized reference */
        if (!this_type.IsUninitializedTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Expected initialization on uninitialized reference "
              << this_type;
          break;
        }

        /*
         * Replace the uninitialized reference with an initialized one. We need to do this for all
         * registers that have the same object instance in them, not just the "this" register.
         */
        work_line_->MarkRefsAsInitialized(this, this_type);
      }
      if (return_type == nullptr) {
        return_type = &reg_types_.FromDescriptor(class_loader_, return_type_descriptor);
      }
      if (!return_type->IsLowHalf()) {
        work_line_->SetResultRegisterType(this, *return_type);
      } else {
        work_line_->SetResultRegisterTypeWide(*return_type, return_type->HighHalf(&reg_types_));
      }
      just_set_result = true;
      break;
    }
    case Instruction::INVOKE_STATIC:
    case Instruction::INVOKE_STATIC_RANGE: {
        bool is_range = (inst->Opcode() == Instruction::INVOKE_STATIC_RANGE);
        ArtMethod* called_method = VerifyInvocationArgs(inst, METHOD_STATIC, is_range);
        const char* descriptor;
        if (called_method == nullptr) {
          uint32_t method_idx = (is_range) ? inst->VRegB_3rc() : inst->VRegB_35c();
          const dex::MethodId& method_id = dex_file_->GetMethodId(method_idx);
          dex::TypeIndex return_type_idx =
              dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
          descriptor = dex_file_->GetTypeDescriptor(return_type_idx);
        } else {
          descriptor = called_method->GetReturnTypeDescriptor();
        }
        const RegType& return_type = reg_types_.FromDescriptor(class_loader_, descriptor);
        if (!return_type.IsLowHalf()) {
          work_line_->SetResultRegisterType(this, return_type);
        } else {
          work_line_->SetResultRegisterTypeWide(return_type, return_type.HighHalf(&reg_types_));
        }
        just_set_result = true;
      }
      break;
    case Instruction::INVOKE_INTERFACE:
    case Instruction::INVOKE_INTERFACE_RANGE: {
      bool is_range =  (inst->Opcode() == Instruction::INVOKE_INTERFACE_RANGE);
      ArtMethod* abs_method = VerifyInvocationArgs(inst, METHOD_INTERFACE, is_range);
      if (abs_method != nullptr) {
        ObjPtr<mirror::Class> called_interface = abs_method->GetDeclaringClass();
        if (!called_interface->IsInterface() && !called_interface->IsObjectClass()) {
          Fail(VERIFY_ERROR_CLASS_CHANGE) << "expected interface class in invoke-interface '"
              << abs_method->PrettyMethod() << "'";
          break;
        }
      }
      /* Get the type of the "this" arg, which should either be a sub-interface of called
       * interface or Object (see comments in RegType::JoinClass).
       */
      const RegType& this_type = work_line_->GetInvocationThis(this, inst);
      if (this_type.IsZeroOrNull()) {
        /* null pointer always passes (and always fails at runtime) */
      } else {
        if (this_type.IsUninitializedTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "interface call on uninitialized object "
              << this_type;
          break;
        }
        // In the past we have tried to assert that "called_interface" is assignable
        // from "this_type.GetClass()", however, as we do an imprecise Join
        // (RegType::JoinClass) we don't have full information on what interfaces are
        // implemented by "this_type". For example, two classes may implement the same
        // interfaces and have a common parent that doesn't implement the interface. The
        // join will set "this_type" to the parent class and a test that this implements
        // the interface will incorrectly fail.
      }
      /*
       * We don't have an object instance, so we can't find the concrete method. However, all of
       * the type information is in the abstract method, so we're good.
       */
      const char* descriptor;
      if (abs_method == nullptr) {
        uint32_t method_idx = (is_range) ? inst->VRegB_3rc() : inst->VRegB_35c();
        const dex::MethodId& method_id = dex_file_->GetMethodId(method_idx);
        dex::TypeIndex return_type_idx =
            dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
        descriptor = dex_file_->GetTypeDescriptor(return_type_idx);
      } else {
        descriptor = abs_method->GetReturnTypeDescriptor();
      }
      const RegType& return_type = reg_types_.FromDescriptor(class_loader_, descriptor);
      if (!return_type.IsLowHalf()) {
        work_line_->SetResultRegisterType(this, return_type);
      } else {
        work_line_->SetResultRegisterTypeWide(return_type, return_type.HighHalf(&reg_types_));
      }
      just_set_result = true;
      break;
    }
    case Instruction::INVOKE_POLYMORPHIC:
    case Instruction::INVOKE_POLYMORPHIC_RANGE: {
      bool is_range = (inst->Opcode() == Instruction::INVOKE_POLYMORPHIC_RANGE);
      ArtMethod* called_method = VerifyInvocationArgs(inst, METHOD_POLYMORPHIC, is_range);
      if (called_method == nullptr) {
        // Convert potential soft failures in VerifyInvocationArgs() to hard errors.
        if (failure_messages_.size() > 0) {
          std::string message = failure_messages_.back()->str();
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << message;
        } else {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invoke-polymorphic verification failure.";
        }
        break;
      }
      if (!CheckSignaturePolymorphicMethod(called_method) ||
          !CheckSignaturePolymorphicReceiver(inst)) {
        DCHECK(HasFailures());
        break;
      }
      const uint16_t vRegH = (is_range) ? inst->VRegH_4rcc() : inst->VRegH_45cc();
      const dex::ProtoIndex proto_idx(vRegH);
      const char* return_descriptor =
          dex_file_->GetReturnTypeDescriptor(dex_file_->GetProtoId(proto_idx));
      const RegType& return_type =
          reg_types_.FromDescriptor(class_loader_, return_descriptor);
      if (!return_type.IsLowHalf()) {
        work_line_->SetResultRegisterType(this, return_type);
      } else {
        work_line_->SetResultRegisterTypeWide(return_type, return_type.HighHalf(&reg_types_));
      }
      just_set_result = true;
      break;
    }
    case Instruction::INVOKE_CUSTOM:
    case Instruction::INVOKE_CUSTOM_RANGE: {
      // Verify registers based on method_type in the call site.
      bool is_range = (inst->Opcode() == Instruction::INVOKE_CUSTOM_RANGE);

      // Step 1. Check the call site that produces the method handle for invocation
      const uint32_t call_site_idx = is_range ? inst->VRegB_3rc() : inst->VRegB_35c();
      if (!CheckCallSite(call_site_idx)) {
        DCHECK(HasFailures());
        break;
      }

      // Step 2. Check the register arguments correspond to the expected arguments for the
      // method handle produced by step 1. The dex file verifier has checked ranges for
      // the first three arguments and CheckCallSite has checked the method handle type.
      const dex::ProtoIndex proto_idx = dex_file_->GetProtoIndexForCallSite(call_site_idx);
      const dex::ProtoId& proto_id = dex_file_->GetProtoId(proto_idx);
      DexFileParameterIterator param_it(*dex_file_, proto_id);
      // Treat method as static as it has yet to be determined.
      VerifyInvocationArgsFromIterator(&param_it, inst, METHOD_STATIC, is_range, nullptr);
      const char* return_descriptor = dex_file_->GetReturnTypeDescriptor(proto_id);

      // Step 3. Propagate return type information
      const RegType& return_type =
          reg_types_.FromDescriptor(class_loader_, return_descriptor);
      if (!return_type.IsLowHalf()) {
        work_line_->SetResultRegisterType(this, return_type);
      } else {
        work_line_->SetResultRegisterTypeWide(return_type, return_type.HighHalf(&reg_types_));
      }
      just_set_result = true;
      break;
    }
    case Instruction::NEG_INT:
    case Instruction::NOT_INT:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Integer(), reg_types_.Integer());
      break;
    case Instruction::NEG_LONG:
    case Instruction::NOT_LONG:
      work_line_->CheckUnaryOpWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                   reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::NEG_FLOAT:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Float(), reg_types_.Float());
      break;
    case Instruction::NEG_DOUBLE:
      work_line_->CheckUnaryOpWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                   reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::INT_TO_LONG:
      work_line_->CheckUnaryOpToWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                     reg_types_.Integer());
      break;
    case Instruction::INT_TO_FLOAT:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Float(), reg_types_.Integer());
      break;
    case Instruction::INT_TO_DOUBLE:
      work_line_->CheckUnaryOpToWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                     reg_types_.Integer());
      break;
    case Instruction::LONG_TO_INT:
      work_line_->CheckUnaryOpFromWide(this, inst, reg_types_.Integer(),
                                       reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::LONG_TO_FLOAT:
      work_line_->CheckUnaryOpFromWide(this, inst, reg_types_.Float(),
                                       reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::LONG_TO_DOUBLE:
      work_line_->CheckUnaryOpWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                   reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::FLOAT_TO_INT:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Integer(), reg_types_.Float());
      break;
    case Instruction::FLOAT_TO_LONG:
      work_line_->CheckUnaryOpToWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                     reg_types_.Float());
      break;
    case Instruction::FLOAT_TO_DOUBLE:
      work_line_->CheckUnaryOpToWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                     reg_types_.Float());
      break;
    case Instruction::DOUBLE_TO_INT:
      work_line_->CheckUnaryOpFromWide(this, inst, reg_types_.Integer(),
                                       reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::DOUBLE_TO_LONG:
      work_line_->CheckUnaryOpWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                   reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::DOUBLE_TO_FLOAT:
      work_line_->CheckUnaryOpFromWide(this, inst, reg_types_.Float(),
                                       reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::INT_TO_BYTE:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Byte(), reg_types_.Integer());
      break;
    case Instruction::INT_TO_CHAR:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Char(), reg_types_.Integer());
      break;
    case Instruction::INT_TO_SHORT:
      work_line_->CheckUnaryOp(this, inst, reg_types_.Short(), reg_types_.Integer());
      break;

    case Instruction::ADD_INT:
    case Instruction::SUB_INT:
    case Instruction::MUL_INT:
    case Instruction::REM_INT:
    case Instruction::DIV_INT:
    case Instruction::SHL_INT:
    case Instruction::SHR_INT:
    case Instruction::USHR_INT:
      work_line_->CheckBinaryOp(this, inst, reg_types_.Integer(), reg_types_.Integer(),
                                reg_types_.Integer(), false);
      break;
    case Instruction::AND_INT:
    case Instruction::OR_INT:
    case Instruction::XOR_INT:
      work_line_->CheckBinaryOp(this, inst, reg_types_.Integer(), reg_types_.Integer(),
                                reg_types_.Integer(), true);
      break;
    case Instruction::ADD_LONG:
    case Instruction::SUB_LONG:
    case Instruction::MUL_LONG:
    case Instruction::DIV_LONG:
    case Instruction::REM_LONG:
    case Instruction::AND_LONG:
    case Instruction::OR_LONG:
    case Instruction::XOR_LONG:
      work_line_->CheckBinaryOpWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                    reg_types_.LongLo(), reg_types_.LongHi(),
                                    reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::SHL_LONG:
    case Instruction::SHR_LONG:
    case Instruction::USHR_LONG:
      /* shift distance is Int, making these different from other binary operations */
      work_line_->CheckBinaryOpWideShift(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                         reg_types_.Integer());
      break;
    case Instruction::ADD_FLOAT:
    case Instruction::SUB_FLOAT:
    case Instruction::MUL_FLOAT:
    case Instruction::DIV_FLOAT:
    case Instruction::REM_FLOAT:
      work_line_->CheckBinaryOp(this, inst, reg_types_.Float(), reg_types_.Float(),
                                reg_types_.Float(), false);
      break;
    case Instruction::ADD_DOUBLE:
    case Instruction::SUB_DOUBLE:
    case Instruction::MUL_DOUBLE:
    case Instruction::DIV_DOUBLE:
    case Instruction::REM_DOUBLE:
      work_line_->CheckBinaryOpWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                    reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                    reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::ADD_INT_2ADDR:
    case Instruction::SUB_INT_2ADDR:
    case Instruction::MUL_INT_2ADDR:
    case Instruction::REM_INT_2ADDR:
    case Instruction::SHL_INT_2ADDR:
    case Instruction::SHR_INT_2ADDR:
    case Instruction::USHR_INT_2ADDR:
      work_line_->CheckBinaryOp2addr(this, inst, reg_types_.Integer(), reg_types_.Integer(),
                                     reg_types_.Integer(), false);
      break;
    case Instruction::AND_INT_2ADDR:
    case Instruction::OR_INT_2ADDR:
    case Instruction::XOR_INT_2ADDR:
      work_line_->CheckBinaryOp2addr(this, inst, reg_types_.Integer(), reg_types_.Integer(),
                                     reg_types_.Integer(), true);
      break;
    case Instruction::DIV_INT_2ADDR:
      work_line_->CheckBinaryOp2addr(this, inst, reg_types_.Integer(), reg_types_.Integer(),
                                     reg_types_.Integer(), false);
      break;
    case Instruction::ADD_LONG_2ADDR:
    case Instruction::SUB_LONG_2ADDR:
    case Instruction::MUL_LONG_2ADDR:
    case Instruction::DIV_LONG_2ADDR:
    case Instruction::REM_LONG_2ADDR:
    case Instruction::AND_LONG_2ADDR:
    case Instruction::OR_LONG_2ADDR:
    case Instruction::XOR_LONG_2ADDR:
      work_line_->CheckBinaryOp2addrWide(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                         reg_types_.LongLo(), reg_types_.LongHi(),
                                         reg_types_.LongLo(), reg_types_.LongHi());
      break;
    case Instruction::SHL_LONG_2ADDR:
    case Instruction::SHR_LONG_2ADDR:
    case Instruction::USHR_LONG_2ADDR:
      work_line_->CheckBinaryOp2addrWideShift(this, inst, reg_types_.LongLo(), reg_types_.LongHi(),
                                              reg_types_.Integer());
      break;
    case Instruction::ADD_FLOAT_2ADDR:
    case Instruction::SUB_FLOAT_2ADDR:
    case Instruction::MUL_FLOAT_2ADDR:
    case Instruction::DIV_FLOAT_2ADDR:
    case Instruction::REM_FLOAT_2ADDR:
      work_line_->CheckBinaryOp2addr(this, inst, reg_types_.Float(), reg_types_.Float(),
                                     reg_types_.Float(), false);
      break;
    case Instruction::ADD_DOUBLE_2ADDR:
    case Instruction::SUB_DOUBLE_2ADDR:
    case Instruction::MUL_DOUBLE_2ADDR:
    case Instruction::DIV_DOUBLE_2ADDR:
    case Instruction::REM_DOUBLE_2ADDR:
      work_line_->CheckBinaryOp2addrWide(this, inst, reg_types_.DoubleLo(), reg_types_.DoubleHi(),
                                         reg_types_.DoubleLo(),  reg_types_.DoubleHi(),
                                         reg_types_.DoubleLo(), reg_types_.DoubleHi());
      break;
    case Instruction::ADD_INT_LIT16:
    case Instruction::RSUB_INT_LIT16:
    case Instruction::MUL_INT_LIT16:
    case Instruction::DIV_INT_LIT16:
    case Instruction::REM_INT_LIT16:
      work_line_->CheckLiteralOp(this, inst, reg_types_.Integer(), reg_types_.Integer(), false,
                                 true);
      break;
    case Instruction::AND_INT_LIT16:
    case Instruction::OR_INT_LIT16:
    case Instruction::XOR_INT_LIT16:
      work_line_->CheckLiteralOp(this, inst, reg_types_.Integer(), reg_types_.Integer(), true,
                                 true);
      break;
    case Instruction::ADD_INT_LIT8:
    case Instruction::RSUB_INT_LIT8:
    case Instruction::MUL_INT_LIT8:
    case Instruction::DIV_INT_LIT8:
    case Instruction::REM_INT_LIT8:
    case Instruction::SHL_INT_LIT8:
    case Instruction::SHR_INT_LIT8:
    case Instruction::USHR_INT_LIT8:
      work_line_->CheckLiteralOp(this, inst, reg_types_.Integer(), reg_types_.Integer(), false,
                                 false);
      break;
    case Instruction::AND_INT_LIT8:
    case Instruction::OR_INT_LIT8:
    case Instruction::XOR_INT_LIT8:
      work_line_->CheckLiteralOp(this, inst, reg_types_.Integer(), reg_types_.Integer(), true,
                                 false);
      break;

    /* These should never appear during verification. */
    case Instruction::UNUSED_3E ... Instruction::UNUSED_43:
    case Instruction::UNUSED_E3 ... Instruction::UNUSED_F9:
    case Instruction::UNUSED_73:
    case Instruction::UNUSED_79:
    case Instruction::UNUSED_7A:
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Unexpected opcode " << inst->DumpString(dex_file_);
      break;

    /*
     * DO NOT add a "default" clause here. Without it the compiler will
     * complain if an instruction is missing (which is desirable).
     */
  }  // end - switch (dec_insn.opcode)

  if (flags_.have_pending_hard_failure_) {
    if (IsAotMode()) {
      /* When AOT compiling, check that the last failure is a hard failure */
      if (failures_[failures_.size() - 1] != VERIFY_ERROR_BAD_CLASS_HARD) {
        LOG(ERROR) << "Pending failures:";
        for (auto& error : failures_) {
          LOG(ERROR) << error;
        }
        for (auto& error_msg : failure_messages_) {
          LOG(ERROR) << error_msg->str();
        }
        LOG(FATAL) << "Pending hard failure, but last failure not hard.";
      }
    }
    /* immediate failure, reject class */
    info_messages_ << "Rejecting opcode " << inst->DumpString(dex_file_);
    return false;
  } else if (flags_.have_pending_runtime_throw_failure_) {
    LogVerifyInfo() << "Elevating opcode flags from " << opcode_flags << " to Throw";
    /* checking interpreter will throw, mark following code as unreachable */
    opcode_flags = Instruction::kThrow;
    // Note: the flag must be reset as it is only global to decouple Fail and is semantically per
    //       instruction. However, RETURN checking may throw LOCKING errors, so we clear at the
    //       very end.
  }
  /*
   * If we didn't just set the result register, clear it out. This ensures that you can only use
   * "move-result" immediately after the result is set. (We could check this statically, but it's
   * not expensive and it makes our debugging output cleaner.)
   */
  if (!just_set_result) {
    work_line_->SetResultTypeToUnknown(GetRegTypeCache());
  }

  /*
   * Handle "branch". Tag the branch target.
   *
   * NOTE: instructions like Instruction::EQZ provide information about the
   * state of the register when the branch is taken or not taken. For example,
   * somebody could get a reference field, check it for zero, and if the
   * branch is taken immediately store that register in a boolean field
   * since the value is known to be zero. We do not currently account for
   * that, and will reject the code.
   *
   * TODO: avoid re-fetching the branch target
   */
  if ((opcode_flags & Instruction::kBranch) != 0) {
    bool isConditional, selfOkay;
    if (!GetBranchOffset(work_insn_idx_, &branch_target, &isConditional, &selfOkay)) {
      /* should never happen after static verification */
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "bad branch";
      return false;
    }
    DCHECK_EQ(isConditional, (opcode_flags & Instruction::kContinue) != 0);
    if (!CheckNotMoveExceptionOrMoveResult(code_item_accessor_.Insns(),
                                           work_insn_idx_ + branch_target)) {
      return false;
    }
    /* update branch target, set "changed" if appropriate */
    if (nullptr != branch_line) {
      if (!UpdateRegisters(work_insn_idx_ + branch_target, branch_line.get(), false)) {
        return false;
      }
    } else {
      if (!UpdateRegisters(work_insn_idx_ + branch_target, work_line_.get(), false)) {
        return false;
      }
    }
  }

  /*
   * Handle "switch". Tag all possible branch targets.
   *
   * We've already verified that the table is structurally sound, so we
   * just need to walk through and tag the targets.
   */
  if ((opcode_flags & Instruction::kSwitch) != 0) {
    int offset_to_switch = insns[1] | (static_cast<int32_t>(insns[2]) << 16);
    const uint16_t* switch_insns = insns + offset_to_switch;
    int switch_count = switch_insns[1];
    int offset_to_targets, targ;

    if ((*insns & 0xff) == Instruction::PACKED_SWITCH) {
      /* 0 = sig, 1 = count, 2/3 = first key */
      offset_to_targets = 4;
    } else {
      /* 0 = sig, 1 = count, 2..count * 2 = keys */
      DCHECK((*insns & 0xff) == Instruction::SPARSE_SWITCH);
      offset_to_targets = 2 + 2 * switch_count;
    }

    /* verify each switch target */
    for (targ = 0; targ < switch_count; targ++) {
      int offset;
      uint32_t abs_offset;

      /* offsets are 32-bit, and only partly endian-swapped */
      offset = switch_insns[offset_to_targets + targ * 2] |
         (static_cast<int32_t>(switch_insns[offset_to_targets + targ * 2 + 1]) << 16);
      abs_offset = work_insn_idx_ + offset;
      DCHECK_LT(abs_offset, code_item_accessor_.InsnsSizeInCodeUnits());
      if (!CheckNotMoveExceptionOrMoveResult(code_item_accessor_.Insns(), abs_offset)) {
        return false;
      }
      if (!UpdateRegisters(abs_offset, work_line_.get(), false)) {
        return false;
      }
    }
  }

  /*
   * Handle instructions that can throw and that are sitting in a "try" block. (If they're not in a
   * "try" block when they throw, control transfers out of the method.)
   */
  if ((opcode_flags & Instruction::kThrow) != 0 && GetInstructionFlags(work_insn_idx_).IsInTry()) {
    bool has_catch_all_handler = false;
    const dex::TryItem* try_item = code_item_accessor_.FindTryItem(work_insn_idx_);
    CHECK(try_item != nullptr);
    CatchHandlerIterator iterator(code_item_accessor_, *try_item);

    // Need the linker to try and resolve the handled class to check if it's Throwable.
    ClassLinker* linker = GetClassLinker();

    for (; iterator.HasNext(); iterator.Next()) {
      dex::TypeIndex handler_type_idx = iterator.GetHandlerTypeIndex();
      if (!handler_type_idx.IsValid()) {
        has_catch_all_handler = true;
      } else {
        // It is also a catch-all if it is java.lang.Throwable.
        ObjPtr<mirror::Class> klass =
            linker->ResolveType(handler_type_idx, dex_cache_, class_loader_);
        if (klass != nullptr) {
          if (klass == GetClassRoot<mirror::Throwable>()) {
            has_catch_all_handler = true;
          }
        } else {
          // Clear exception.
          DCHECK(self_->IsExceptionPending());
          self_->ClearException();
        }
      }
      /*
       * Merge registers into the "catch" block. We want to use the "savedRegs" rather than
       * "work_regs", because at runtime the exception will be thrown before the instruction
       * modifies any registers.
       */
      if (kVerifierDebug) {
        LogVerifyInfo() << "Updating exception handler 0x"
                        << std::hex << iterator.GetHandlerAddress();
      }
      if (!UpdateRegisters(iterator.GetHandlerAddress(), saved_line_.get(), false)) {
        return false;
      }
    }

    /*
     * If the monitor stack depth is nonzero, there must be a "catch all" handler for this
     * instruction. This does apply to monitor-exit because of async exception handling.
     */
    if (work_line_->MonitorStackDepth() > 0 && !has_catch_all_handler) {
      /*
       * The state in work_line reflects the post-execution state. If the current instruction is a
       * monitor-enter and the monitor stack was empty, we don't need a catch-all (if it throws,
       * it will do so before grabbing the lock).
       */
      if (inst->Opcode() != Instruction::MONITOR_ENTER || work_line_->MonitorStackDepth() != 1) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD)
            << "expected to be within a catch-all for an instruction where a monitor is held";
        return false;
      }
    }
  }

  /* Handle "continue". Tag the next consecutive instruction.
   *  Note: Keep the code handling "continue" case below the "branch" and "switch" cases,
   *        because it changes work_line_ when performing peephole optimization
   *        and this change should not be used in those cases.
   */
  if ((opcode_flags & Instruction::kContinue) != 0 && !exc_handler_unreachable) {
    DCHECK_EQ(&code_item_accessor_.InstructionAt(work_insn_idx_), inst);
    uint32_t next_insn_idx = work_insn_idx_ + inst->SizeInCodeUnits();
    if (next_insn_idx >= code_item_accessor_.InsnsSizeInCodeUnits()) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Execution can walk off end of code area";
      return false;
    }
    // The only way to get to a move-exception instruction is to get thrown there. Make sure the
    // next instruction isn't one.
    if (!CheckNotMoveException(code_item_accessor_.Insns(), next_insn_idx)) {
      return false;
    }
    if (nullptr != fallthrough_line) {
      // Make workline consistent with fallthrough computed from peephole optimization.
      work_line_->CopyFromLine(fallthrough_line.get());
    }
    if (GetInstructionFlags(next_insn_idx).IsReturn()) {
      // For returns we only care about the operand to the return, all other registers are dead.
      const Instruction* ret_inst = &code_item_accessor_.InstructionAt(next_insn_idx);
      AdjustReturnLine(this, ret_inst, work_line_.get());
    }
    RegisterLine* next_line = reg_table_.GetLine(next_insn_idx);
    if (next_line != nullptr) {
      // Merge registers into what we have for the next instruction, and set the "changed" flag if
      // needed. If the merge changes the state of the registers then the work line will be
      // updated.
      if (!UpdateRegisters(next_insn_idx, work_line_.get(), true)) {
        return false;
      }
    } else {
      /*
       * We're not recording register data for the next instruction, so we don't know what the
       * prior state was. We have to assume that something has changed and re-evaluate it.
       */
      GetModifiableInstructionFlags(next_insn_idx).SetChanged();
    }
  }

  /* If we're returning from the method, make sure monitor stack is empty. */
  if ((opcode_flags & Instruction::kReturn) != 0) {
    work_line_->VerifyMonitorStackEmpty(this);
  }

  /*
   * Update start_guess. Advance to the next instruction of that's
   * possible, otherwise use the branch target if one was found. If
   * neither of those exists we're in a return or throw; leave start_guess
   * alone and let the caller sort it out.
   */
  if ((opcode_flags & Instruction::kContinue) != 0) {
    DCHECK_EQ(&code_item_accessor_.InstructionAt(work_insn_idx_), inst);
    *start_guess = work_insn_idx_ + inst->SizeInCodeUnits();
  } else if ((opcode_flags & Instruction::kBranch) != 0) {
    /* we're still okay if branch_target is zero */
    *start_guess = work_insn_idx_ + branch_target;
  }

  DCHECK_LT(*start_guess, code_item_accessor_.InsnsSizeInCodeUnits());
  DCHECK(GetInstructionFlags(*start_guess).IsOpcode());

  if (flags_.have_pending_runtime_throw_failure_) {
    Fail(VERIFY_ERROR_RUNTIME_THROW, /* pending_exc= */ false);
    // Reset the pending_runtime_throw flag now.
    flags_.have_pending_runtime_throw_failure_ = false;
  }

  return true;
}  // NOLINT(readability/fn_size)

template <bool kVerifierDebug>
template <CheckAccess C>
const RegType& MethodVerifier<kVerifierDebug>::ResolveClass(dex::TypeIndex class_idx) {
  ClassLinker* linker = GetClassLinker();
  ObjPtr<mirror::Class> klass = CanLoadClasses()
      ? linker->ResolveType(class_idx, dex_cache_, class_loader_)
      : linker->LookupResolvedType(class_idx, dex_cache_.Get(), class_loader_.Get());
  if (CanLoadClasses() && klass == nullptr) {
    DCHECK(self_->IsExceptionPending());
    self_->ClearException();
  }
  const RegType* result = nullptr;
  if (klass != nullptr) {
    bool precise = klass->CannotBeAssignedFromOtherTypes();
    if (precise && !IsInstantiableOrPrimitive(klass)) {
      const char* descriptor = dex_file_->GetTypeDescriptor(class_idx);
      UninstantiableError(descriptor);
      precise = false;
    }
    result = reg_types_.FindClass(klass, precise);
    if (result == nullptr) {
      const char* descriptor = dex_file_->GetTypeDescriptor(class_idx);
      result = reg_types_.InsertClass(descriptor, klass, precise);
    }
  } else {
    const char* descriptor = dex_file_->GetTypeDescriptor(class_idx);
    result = &reg_types_.FromDescriptor(class_loader_, descriptor);
  }
  DCHECK(result != nullptr);
  if (result->IsConflict()) {
    const char* descriptor = dex_file_->GetTypeDescriptor(class_idx);
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "accessing broken descriptor '" << descriptor
        << "' in " << GetDeclaringClass();
    return *result;
  }

  // If requested, check if access is allowed. Unresolved types are included in this check, as the
  // interpreter only tests whether access is allowed when a class is not pre-verified and runs in
  // the access-checks interpreter. If result is primitive, skip the access check.
  //
  // Note: we do this for unresolved classes to trigger re-verification at runtime.
  if (C != CheckAccess::kNo &&
      result->IsNonZeroReferenceTypes() &&
      ((C == CheckAccess::kYes && IsSdkVersionSetAndAtLeast(api_level_, SdkVersion::kP))
          || !result->IsUnresolvedTypes())) {
    const RegType& referrer = GetDeclaringClass();
    if ((IsSdkVersionSetAndAtLeast(api_level_, SdkVersion::kP) || !referrer.IsUnresolvedTypes()) &&
        !referrer.CanAccess(*result)) {
      if (IsAotMode()) {
        Fail(VERIFY_ERROR_ACCESS_CLASS);
        VLOG(verifier)
            << "(possibly) illegal class access: '" << referrer << "' -> '" << *result << "'";
      } else {
        Fail(VERIFY_ERROR_ACCESS_CLASS)
            << "(possibly) illegal class access: '" << referrer << "' -> '" << *result << "'";
      }
    }
  }
  return *result;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::HandleMoveException(const Instruction* inst)  {
  // We do not allow MOVE_EXCEPTION as the first instruction in a method. This is a simple case
  // where one entrypoint to the catch block is not actually an exception path.
  if (work_insn_idx_ == 0) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "move-exception at pc 0x0";
    return true;
  }
  /*
   * This statement can only appear as the first instruction in an exception handler. We verify
   * that as part of extracting the exception type from the catch block list.
   */
  auto caught_exc_type_fn = [&]() REQUIRES_SHARED(Locks::mutator_lock_) ->
      std::pair<bool, const RegType*> {
    const RegType* common_super = nullptr;
    if (code_item_accessor_.TriesSize() != 0) {
      const uint8_t* handlers_ptr = code_item_accessor_.GetCatchHandlerData();
      uint32_t handlers_size = DecodeUnsignedLeb128(&handlers_ptr);
      const RegType* unresolved = nullptr;
      for (uint32_t i = 0; i < handlers_size; i++) {
        CatchHandlerIterator iterator(handlers_ptr);
        for (; iterator.HasNext(); iterator.Next()) {
          if (iterator.GetHandlerAddress() == (uint32_t) work_insn_idx_) {
            if (!iterator.GetHandlerTypeIndex().IsValid()) {
              common_super = &reg_types_.JavaLangThrowable();
            } else {
              // Do access checks only on resolved exception classes.
              const RegType& exception =
                  ResolveClass<CheckAccess::kOnResolvedClass>(iterator.GetHandlerTypeIndex());
              if (!reg_types_.JavaLangThrowable().IsAssignableFrom(exception, this)) {
                DCHECK(!exception.IsUninitializedTypes());  // Comes from dex, shouldn't be uninit.
                if (exception.IsUnresolvedTypes()) {
                  if (unresolved == nullptr) {
                    unresolved = &exception;
                  } else {
                    unresolved = &unresolved->SafeMerge(exception, &reg_types_, this);
                  }
                } else {
                  Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected non-throwable class "
                                                    << exception;
                  return std::make_pair(true, &reg_types_.Conflict());
                }
              } else if (common_super == nullptr) {
                common_super = &exception;
              } else if (common_super->Equals(exception)) {
                // odd case, but nothing to do
              } else {
                common_super = &common_super->Merge(exception, &reg_types_, this);
                if (FailOrAbort(reg_types_.JavaLangThrowable().IsAssignableFrom(
                    *common_super, this),
                    "java.lang.Throwable is not assignable-from common_super at ",
                    work_insn_idx_)) {
                  break;
                }
              }
            }
          }
        }
        handlers_ptr = iterator.EndDataPointer();
      }
      if (unresolved != nullptr) {
        // Soft-fail, but do not handle this with a synthetic throw.
        Fail(VERIFY_ERROR_UNRESOLVED_TYPE_CHECK, /*pending_exc=*/ false)
            << "Unresolved catch handler";
        bool should_continue = true;
        if (common_super != nullptr) {
          unresolved = &unresolved->Merge(*common_super, &reg_types_, this);
        } else {
          should_continue = !PotentiallyMarkRuntimeThrow();
        }
        return std::make_pair(should_continue, unresolved);
      }
    }
    if (common_super == nullptr) {
      /* No catch block */
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unable to find exception handler";
      return std::make_pair(true, &reg_types_.Conflict());
    }
    return std::make_pair(true, common_super);
  };
  auto result = caught_exc_type_fn();
  work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_11x(), *result.second);
  return result.first;
}

template <bool kVerifierDebug>
ArtMethod* MethodVerifier<kVerifierDebug>::ResolveMethodAndCheckAccess(
    uint32_t dex_method_idx, MethodType method_type) {
  const dex::MethodId& method_id = dex_file_->GetMethodId(dex_method_idx);
  const RegType& klass_type = ResolveClass<CheckAccess::kYes>(method_id.class_idx_);
  if (klass_type.IsConflict()) {
    std::string append(" in attempt to access method ");
    append += dex_file_->GetMethodName(method_id);
    AppendToLastFailMessage(append);
    return nullptr;
  }
  if (klass_type.IsUnresolvedTypes()) {
    return nullptr;  // Can't resolve Class so no more to do here
  }
  ObjPtr<mirror::Class> klass = klass_type.GetClass();
  const RegType& referrer = GetDeclaringClass();
  ClassLinker* class_linker = GetClassLinker();

  ArtMethod* res_method = dex_cache_->GetResolvedMethod(dex_method_idx);
  if (res_method == nullptr) {
    res_method = class_linker->FindResolvedMethod(
        klass, dex_cache_.Get(), class_loader_.Get(), dex_method_idx);
  }

  bool must_fail = false;
  // This is traditional and helps with screwy bytecode. It will tell you that, yes, a method
  // exists, but that it's called incorrectly. This significantly helps debugging, as locally it's
  // hard to see the differences.
  // If we don't have res_method here we must fail. Just use this bool to make sure of that with a
  // DCHECK.
  if (res_method == nullptr) {
    must_fail = true;
    // Try to find the method also with the other type for better error reporting below
    // but do not store such bogus lookup result in the DexCache or VerifierDeps.
    res_method = class_linker->FindIncompatibleMethod(
        klass, dex_cache_.Get(), class_loader_.Get(), dex_method_idx);
  }

  if (res_method == nullptr) {
    Fail(VERIFY_ERROR_NO_METHOD) << "couldn't find method "
                                 << klass->PrettyDescriptor() << "."
                                 << dex_file_->GetMethodName(method_id) << " "
                                 << dex_file_->GetMethodSignature(method_id);
    return nullptr;
  }

  // Make sure calls to constructors are "direct". There are additional restrictions but we don't
  // enforce them here.
  if (res_method->IsConstructor() && method_type != METHOD_DIRECT) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "rejecting non-direct call to constructor "
                                      << res_method->PrettyMethod();
    return nullptr;
  }
  // Disallow any calls to class initializers.
  if (res_method->IsClassInitializer()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "rejecting call to class initializer "
                                      << res_method->PrettyMethod();
    return nullptr;
  }

  // Check that interface methods are static or match interface classes.
  // We only allow statics if we don't have default methods enabled.
  //
  // Note: this check must be after the initializer check, as those are required to fail a class,
  //       while this check implies an IncompatibleClassChangeError.
  if (klass->IsInterface()) {
    // methods called on interfaces should be invoke-interface, invoke-super, invoke-direct (if
    // default methods are supported for the dex file), or invoke-static.
    if (method_type != METHOD_INTERFACE &&
        method_type != METHOD_STATIC &&
        (!dex_file_->SupportsDefaultMethods() ||
         method_type != METHOD_DIRECT) &&
        method_type != METHOD_SUPER) {
      Fail(VERIFY_ERROR_CLASS_CHANGE)
          << "non-interface method " << dex_file_->PrettyMethod(dex_method_idx)
          << " is in an interface class " << klass->PrettyClass();
      return nullptr;
    }
  } else {
    if (method_type == METHOD_INTERFACE) {
      Fail(VERIFY_ERROR_CLASS_CHANGE)
          << "interface method " << dex_file_->PrettyMethod(dex_method_idx)
          << " is in a non-interface class " << klass->PrettyClass();
      return nullptr;
    }
  }

  // Check specifically for non-public object methods being provided for interface dispatch. This
  // can occur if we failed to find a method with FindInterfaceMethod but later find one with
  // FindClassMethod for error message use.
  if (method_type == METHOD_INTERFACE &&
      res_method->GetDeclaringClass()->IsObjectClass() &&
      !res_method->IsPublic()) {
    Fail(VERIFY_ERROR_NO_METHOD) << "invoke-interface " << klass->PrettyDescriptor() << "."
                                 << dex_file_->GetMethodName(method_id) << " "
                                 << dex_file_->GetMethodSignature(method_id) << " resolved to "
                                 << "non-public object method " << res_method->PrettyMethod() << " "
                                 << "but non-public Object methods are excluded from interface "
                                 << "method resolution.";
    return nullptr;
  }
  // Check if access is allowed.
  if (!referrer.CanAccessMember(res_method->GetDeclaringClass(), res_method->GetAccessFlags())) {
    Fail(VERIFY_ERROR_ACCESS_METHOD) << "illegal method access (call "
                                     << res_method->PrettyMethod()
                                     << " from " << referrer << ")";
    return res_method;
  }
  // Check that invoke-virtual and invoke-super are not used on private methods of the same class.
  if (res_method->IsPrivate() && (method_type == METHOD_VIRTUAL || method_type == METHOD_SUPER)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invoke-super/virtual can't be used on private method "
                                      << res_method->PrettyMethod();
    return nullptr;
  }
  // See if the method type implied by the invoke instruction matches the access flags for the
  // target method. The flags for METHOD_POLYMORPHIC are based on there being precisely two
  // signature polymorphic methods supported by the run-time which are native methods with variable
  // arguments.
  if ((method_type == METHOD_DIRECT && (!res_method->IsDirect() || res_method->IsStatic())) ||
      (method_type == METHOD_STATIC && !res_method->IsStatic()) ||
      ((method_type == METHOD_SUPER ||
        method_type == METHOD_VIRTUAL ||
        method_type == METHOD_INTERFACE) && res_method->IsDirect()) ||
      ((method_type == METHOD_POLYMORPHIC) &&
       (!res_method->IsNative() || !res_method->IsVarargs()))) {
    Fail(VERIFY_ERROR_CLASS_CHANGE) << "invoke type (" << method_type << ") does not match method "
                                       "type of " << res_method->PrettyMethod();
    return nullptr;
  }
  // Make sure we weren't expecting to fail.
  DCHECK(!must_fail) << "invoke type (" << method_type << ")"
                     << klass->PrettyDescriptor() << "."
                     << dex_file_->GetMethodName(method_id) << " "
                     << dex_file_->GetMethodSignature(method_id) << " unexpectedly resolved to "
                     << res_method->PrettyMethod() << " without error. Initially this method was "
                     << "not found so we were expecting to fail for some reason.";
  return res_method;
}

template <bool kVerifierDebug>
template <class T>
ArtMethod* MethodVerifier<kVerifierDebug>::VerifyInvocationArgsFromIterator(
    T* it, const Instruction* inst, MethodType method_type, bool is_range, ArtMethod* res_method) {
  DCHECK_EQ(!is_range, inst->HasVarArgs());

  // We use vAA as our expected arg count, rather than res_method->insSize, because we need to
  // match the call to the signature. Also, we might be calling through an abstract method
  // definition (which doesn't have register count values).
  const size_t expected_args = inst->VRegA();
  /* caught by static verifier */
  DCHECK(is_range || expected_args <= 5);

  if (expected_args > code_item_accessor_.OutsSize()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invalid argument count (" << expected_args
                                      << ") exceeds outsSize ("
                                      << code_item_accessor_.OutsSize() << ")";
    return nullptr;
  }

  /*
   * Check the "this" argument, which must be an instance of the class that declared the method.
   * For an interface class, we don't do the full interface merge (see JoinClass), so we can't do a
   * rigorous check here (which is okay since we have to do it at runtime).
   */
  if (method_type != METHOD_STATIC) {
    const RegType& actual_arg_type = work_line_->GetInvocationThis(this, inst);
    if (actual_arg_type.IsConflict()) {  // GetInvocationThis failed.
      CHECK(flags_.have_pending_hard_failure_);
      return nullptr;
    }
    bool is_init = false;
    if (actual_arg_type.IsUninitializedTypes()) {
      if (res_method != nullptr) {
        if (!res_method->IsConstructor()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "'this' arg must be initialized";
          return nullptr;
        }
      } else {
        // Check whether the name of the called method is "<init>"
        const uint32_t method_idx = GetMethodIdxOfInvoke(inst);
        if (strcmp(dex_file_->GetMethodName(dex_file_->GetMethodId(method_idx)), "<init>") != 0) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "'this' arg must be initialized";
          return nullptr;
        }
      }
      is_init = true;
    }
    const RegType& adjusted_type = is_init
                                       ? GetRegTypeCache()->FromUninitialized(actual_arg_type)
                                       : actual_arg_type;
    if (method_type != METHOD_INTERFACE && !adjusted_type.IsZeroOrNull()) {
      const RegType* res_method_class;
      // Miranda methods have the declaring interface as their declaring class, not the abstract
      // class. It would be wrong to use this for the type check (interface type checks are
      // postponed to runtime).
      if (res_method != nullptr && !res_method->IsMiranda()) {
        ObjPtr<mirror::Class> klass = res_method->GetDeclaringClass();
        std::string temp;
        res_method_class = &FromClass(klass->GetDescriptor(&temp), klass,
                                      klass->CannotBeAssignedFromOtherTypes());
      } else {
        const uint32_t method_idx = GetMethodIdxOfInvoke(inst);
        const dex::TypeIndex class_idx = dex_file_->GetMethodId(method_idx).class_idx_;
        res_method_class =
            &reg_types_.FromDescriptor(class_loader_, dex_file_->GetTypeDescriptor(class_idx));
      }
      if (!res_method_class->IsAssignableFrom(adjusted_type, this)) {
        Fail(adjusted_type.IsUnresolvedTypes()
                 ? VERIFY_ERROR_UNRESOLVED_TYPE_CHECK
                 : VERIFY_ERROR_BAD_CLASS_HARD)
            << "'this' argument '" << actual_arg_type << "' not instance of '"
            << *res_method_class << "'";
        // Continue on soft failures. We need to find possible hard failures to avoid problems in
        // the compiler.
        if (flags_.have_pending_hard_failure_) {
          return nullptr;
        }
      }
    }
  }

  uint32_t arg[5];
  if (!is_range) {
    inst->GetVarArgs(arg);
  }
  uint32_t sig_registers = (method_type == METHOD_STATIC) ? 0 : 1;
  for ( ; it->HasNext(); it->Next()) {
    if (sig_registers >= expected_args) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Rejecting invocation, expected " << inst->VRegA() <<
          " argument registers, method signature has " << sig_registers + 1 << " or more";
      return nullptr;
    }

    const char* param_descriptor = it->GetDescriptor();

    if (param_descriptor == nullptr) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Rejecting invocation because of missing signature "
          "component";
      return nullptr;
    }

    const RegType& reg_type = reg_types_.FromDescriptor(class_loader_, param_descriptor);
    uint32_t get_reg = is_range ? inst->VRegC() + static_cast<uint32_t>(sig_registers) :
        arg[sig_registers];
    if (reg_type.IsIntegralTypes()) {
      const RegType& src_type = work_line_->GetRegisterType(this, get_reg);
      if (!src_type.IsIntegralTypes()) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "register v" << get_reg << " has type " << src_type
            << " but expected " << reg_type;
        return nullptr;
      }
    } else {
      if (!work_line_->VerifyRegisterType(this, get_reg, reg_type)) {
        // Continue on soft failures. We need to find possible hard failures to avoid problems in
        // the compiler.
        if (flags_.have_pending_hard_failure_) {
          return nullptr;
        }
      } else if (reg_type.IsLongOrDoubleTypes()) {
        // Check that registers are consecutive (for non-range invokes). Invokes are the only
        // instructions not specifying register pairs by the first component, but require them
        // nonetheless. Only check when there's an actual register in the parameters. If there's
        // none, this will fail below.
        if (!is_range && sig_registers + 1 < expected_args) {
          uint32_t second_reg = arg[sig_registers + 1];
          if (second_reg != get_reg + 1) {
            Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Rejecting invocation, long or double parameter "
                "at index " << sig_registers << " is not a pair: " << get_reg << " + "
                << second_reg << ".";
            return nullptr;
          }
        }
      }
    }
    sig_registers += reg_type.IsLongOrDoubleTypes() ?  2 : 1;
  }
  if (expected_args != sig_registers) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Rejecting invocation, expected " << expected_args <<
        " argument registers, method signature has " << sig_registers;
    return nullptr;
  }
  return res_method;
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::VerifyInvocationArgsUnresolvedMethod(const Instruction* inst,
                                                                          MethodType method_type,
                                                                          bool is_range) {
  // As the method may not have been resolved, make this static check against what we expect.
  // The main reason for this code block is to fail hard when we find an illegal use, e.g.,
  // wrong number of arguments or wrong primitive types, even if the method could not be resolved.
  const uint32_t method_idx = GetMethodIdxOfInvoke(inst);
  DexFileParameterIterator it(*dex_file_,
                              dex_file_->GetProtoId(dex_file_->GetMethodId(method_idx).proto_idx_));
  VerifyInvocationArgsFromIterator(&it, inst, method_type, is_range, nullptr);
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckCallSite(uint32_t call_site_idx) {
  if (call_site_idx >= dex_file_->NumCallSiteIds()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Bad call site id #" << call_site_idx
                                      << " >= " << dex_file_->NumCallSiteIds();
    return false;
  }

  CallSiteArrayValueIterator it(*dex_file_, dex_file_->GetCallSiteId(call_site_idx));
  // Check essential arguments are provided. The dex file verifier has verified indices of the
  // main values (method handle, name, method_type).
  static const size_t kRequiredArguments = 3;
  if (it.Size() < kRequiredArguments) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Call site #" << call_site_idx
                                      << " has too few arguments: "
                                      << it.Size() << " < " << kRequiredArguments;
    return false;
  }

  std::pair<const EncodedArrayValueIterator::ValueType, size_t> type_and_max[kRequiredArguments] =
      { { EncodedArrayValueIterator::ValueType::kMethodHandle, dex_file_->NumMethodHandles() },
        { EncodedArrayValueIterator::ValueType::kString, dex_file_->NumStringIds() },
        { EncodedArrayValueIterator::ValueType::kMethodType, dex_file_->NumProtoIds() }
      };
  uint32_t index[kRequiredArguments];

  // Check arguments have expected types and are within permitted ranges.
  for (size_t i = 0; i < kRequiredArguments; ++i) {
    if (it.GetValueType() != type_and_max[i].first) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Call site id #" << call_site_idx
                                        << " argument " << i << " has wrong type "
                                        << it.GetValueType() << "!=" << type_and_max[i].first;
      return false;
    }
    index[i] = static_cast<uint32_t>(it.GetJavaValue().i);
    if (index[i] >= type_and_max[i].second) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Call site id #" << call_site_idx
                                        << " argument " << i << " bad index "
                                        << index[i] << " >= " << type_and_max[i].second;
      return false;
    }
    it.Next();
  }

  // Check method handle kind is valid.
  const dex::MethodHandleItem& mh = dex_file_->GetMethodHandle(index[0]);
  if (mh.method_handle_type_ != static_cast<uint16_t>(DexFile::MethodHandleType::kInvokeStatic)) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Call site #" << call_site_idx
                                      << " argument 0 method handle type is not InvokeStatic: "
                                      << mh.method_handle_type_;
    return false;
  }
  return true;
}

class MethodParamListDescriptorIterator {
 public:
  explicit MethodParamListDescriptorIterator(ArtMethod* res_method) :
      res_method_(res_method), pos_(0), params_(res_method->GetParameterTypeList()),
      params_size_(params_ == nullptr ? 0 : params_->Size()) {
  }

  bool HasNext() {
    return pos_ < params_size_;
  }

  void Next() {
    ++pos_;
  }

  const char* GetDescriptor() REQUIRES_SHARED(Locks::mutator_lock_) {
    return res_method_->GetTypeDescriptorFromTypeIdx(params_->GetTypeItem(pos_).type_idx_);
  }

 private:
  ArtMethod* res_method_;
  size_t pos_;
  const dex::TypeList* params_;
  const size_t params_size_;
};

template <bool kVerifierDebug>
ArtMethod* MethodVerifier<kVerifierDebug>::VerifyInvocationArgs(
    const Instruction* inst, MethodType method_type, bool is_range) {
  // Resolve the method. This could be an abstract or concrete method depending on what sort of call
  // we're making.
  const uint32_t method_idx = GetMethodIdxOfInvoke(inst);
  ArtMethod* res_method = ResolveMethodAndCheckAccess(method_idx, method_type);
  if (res_method == nullptr) {  // error or class is unresolved
    // Check what we can statically.
    if (!flags_.have_pending_hard_failure_) {
      VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
    }
    return nullptr;
  }

  // If we're using invoke-super(method), make sure that the executing method's class' superclass
  // has a vtable entry for the target method. Or the target is on a interface.
  if (method_type == METHOD_SUPER) {
    dex::TypeIndex class_idx = dex_file_->GetMethodId(method_idx).class_idx_;
    const RegType& reference_type =
        reg_types_.FromDescriptor(class_loader_, dex_file_->GetTypeDescriptor(class_idx));
    if (reference_type.IsUnresolvedTypes()) {
      // We cannot differentiate on whether this is a class change error or just
      // a missing method. This will be handled at runtime.
      Fail(VERIFY_ERROR_NO_METHOD) << "Unable to find referenced class from invoke-super";
      VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
      return nullptr;
    }
    if (reference_type.GetClass()->IsInterface()) {
      if (!GetDeclaringClass().HasClass()) {
        Fail(VERIFY_ERROR_NO_CLASS) << "Unable to resolve the full class of 'this' used in an"
                                    << "interface invoke-super";
        VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
        return nullptr;
      } else if (!reference_type.IsStrictlyAssignableFrom(GetDeclaringClass(), this)) {
        Fail(VERIFY_ERROR_CLASS_CHANGE)
            << "invoke-super in " << mirror::Class::PrettyClass(GetDeclaringClass().GetClass())
            << " in method "
            << dex_file_->PrettyMethod(dex_method_idx_) << " to method "
            << dex_file_->PrettyMethod(method_idx) << " references "
            << "non-super-interface type " << mirror::Class::PrettyClass(reference_type.GetClass());
        VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
        return nullptr;
      }
    } else {
      const RegType& super = GetDeclaringClass().GetSuperClass(&reg_types_);
      if (super.IsUnresolvedTypes()) {
        Fail(VERIFY_ERROR_NO_METHOD) << "unknown super class in invoke-super from "
                                    << dex_file_->PrettyMethod(dex_method_idx_)
                                    << " to super " << res_method->PrettyMethod();
        VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
        return nullptr;
      }
      if (!reference_type.IsStrictlyAssignableFrom(GetDeclaringClass(), this) ||
          (res_method->GetMethodIndex() >= super.GetClass()->GetVTableLength())) {
        Fail(VERIFY_ERROR_NO_METHOD) << "invalid invoke-super from "
                                    << dex_file_->PrettyMethod(dex_method_idx_)
                                    << " to super " << super
                                    << "." << res_method->GetName()
                                    << res_method->GetSignature();
        VerifyInvocationArgsUnresolvedMethod(inst, method_type, is_range);
        return nullptr;
      }
    }
  }

  if (UNLIKELY(method_type == METHOD_POLYMORPHIC)) {
    // Process the signature of the calling site that is invoking the method handle.
    dex::ProtoIndex proto_idx(inst->VRegH());
    DexFileParameterIterator it(*dex_file_, dex_file_->GetProtoId(proto_idx));
    return VerifyInvocationArgsFromIterator(&it, inst, method_type, is_range, res_method);
  } else {
    // Process the target method's signature.
    MethodParamListDescriptorIterator it(res_method);
    return VerifyInvocationArgsFromIterator(&it, inst, method_type, is_range, res_method);
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckSignaturePolymorphicMethod(ArtMethod* method) {
  ObjPtr<mirror::Class> klass = method->GetDeclaringClass();
  const char* method_name = method->GetName();

  const char* expected_return_descriptor;
  ObjPtr<mirror::ObjectArray<mirror::Class>> class_roots = GetClassLinker()->GetClassRoots();
  if (klass == GetClassRoot<mirror::MethodHandle>(class_roots)) {
    expected_return_descriptor = mirror::MethodHandle::GetReturnTypeDescriptor(method_name);
  } else if (klass == GetClassRoot<mirror::VarHandle>(class_roots)) {
    expected_return_descriptor = mirror::VarHandle::GetReturnTypeDescriptor(method_name);
  } else {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "Signature polymorphic method in unsuppported class: " << klass->PrettyDescriptor();
    return false;
  }

  if (expected_return_descriptor == nullptr) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "Signature polymorphic method name invalid: " << method_name;
    return false;
  }

  const dex::TypeList* types = method->GetParameterTypeList();
  if (types->Size() != 1) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "Signature polymorphic method has too many arguments " << types->Size() << " != 1";
    return false;
  }

  const dex::TypeIndex argument_type_index = types->GetTypeItem(0).type_idx_;
  const char* argument_descriptor = method->GetTypeDescriptorFromTypeIdx(argument_type_index);
  if (strcmp(argument_descriptor, "[Ljava/lang/Object;") != 0) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "Signature polymorphic method has unexpected argument type: " << argument_descriptor;
    return false;
  }

  const char* return_descriptor = method->GetReturnTypeDescriptor();
  if (strcmp(return_descriptor, expected_return_descriptor) != 0) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "Signature polymorphic method has unexpected return type: " << return_descriptor
        << " != " << expected_return_descriptor;
    return false;
  }

  return true;
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::CheckSignaturePolymorphicReceiver(const Instruction* inst) {
  const RegType& this_type = work_line_->GetInvocationThis(this, inst);
  if (this_type.IsZeroOrNull()) {
    /* null pointer always passes (and always fails at run time) */
    return true;
  } else if (!this_type.IsNonZeroReferenceTypes()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "invoke-polymorphic receiver is not a reference: "
        << this_type;
    return false;
  } else if (this_type.IsUninitializedReference()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "invoke-polymorphic receiver is uninitialized: "
        << this_type;
    return false;
  } else if (!this_type.HasClass()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "invoke-polymorphic receiver has no class: "
        << this_type;
    return false;
  } else {
    ObjPtr<mirror::ObjectArray<mirror::Class>> class_roots = GetClassLinker()->GetClassRoots();
    if (!this_type.GetClass()->IsSubClass(GetClassRoot<mirror::MethodHandle>(class_roots)) &&
        !this_type.GetClass()->IsSubClass(GetClassRoot<mirror::VarHandle>(class_roots))) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD)
          << "invoke-polymorphic receiver is not a subclass of MethodHandle or VarHandle: "
          << this_type;
      return false;
    }
  }
  return true;
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::VerifyNewArray(const Instruction* inst,
                                                    bool is_filled,
                                                    bool is_range) {
  dex::TypeIndex type_idx;
  if (!is_filled) {
    DCHECK_EQ(inst->Opcode(), Instruction::NEW_ARRAY);
    type_idx = dex::TypeIndex(inst->VRegC_22c());
  } else if (!is_range) {
    DCHECK_EQ(inst->Opcode(), Instruction::FILLED_NEW_ARRAY);
    type_idx = dex::TypeIndex(inst->VRegB_35c());
  } else {
    DCHECK_EQ(inst->Opcode(), Instruction::FILLED_NEW_ARRAY_RANGE);
    type_idx = dex::TypeIndex(inst->VRegB_3rc());
  }
  const RegType& res_type = ResolveClass<CheckAccess::kYes>(type_idx);
  if (res_type.IsConflict()) {  // bad class
    DCHECK_NE(failures_.size(), 0U);
  } else {
    // TODO: check Compiler::CanAccessTypeWithoutChecks returns false when res_type is unresolved
    if (!res_type.IsArrayTypes()) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "new-array on non-array class " << res_type;
    } else if (!is_filled) {
      /* make sure "size" register is valid type */
      work_line_->VerifyRegisterType(this, inst->VRegB_22c(), reg_types_.Integer());
      /* set register type to array class */
      const RegType& precise_type = reg_types_.FromUninitialized(res_type);
      work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_22c(), precise_type);
    } else {
      DCHECK(!res_type.IsUnresolvedMergedReference());
      // Verify each register. If "arg_count" is bad, VerifyRegisterType() will run off the end of
      // the list and fail. It's legal, if silly, for arg_count to be zero.
      const RegType& expected_type = reg_types_.GetComponentType(res_type, class_loader_);
      uint32_t arg_count = (is_range) ? inst->VRegA_3rc() : inst->VRegA_35c();
      uint32_t arg[5];
      if (!is_range) {
        inst->GetVarArgs(arg);
      }
      for (size_t ui = 0; ui < arg_count; ui++) {
        uint32_t get_reg = is_range ? inst->VRegC_3rc() + ui : arg[ui];
        work_line_->VerifyRegisterType(this, get_reg, expected_type);
      }
      // filled-array result goes into "result" register
      const RegType& precise_type = reg_types_.FromUninitialized(res_type);
      work_line_->SetResultRegisterType(this, precise_type);
    }
  }
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::VerifyAGet(const Instruction* inst,
                                                const RegType& insn_type,
                                                bool is_primitive) {
  const RegType& index_type = work_line_->GetRegisterType(this, inst->VRegC_23x());
  if (!index_type.IsArrayIndexTypes()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Invalid reg type for array index (" << index_type << ")";
  } else {
    const RegType& array_type = work_line_->GetRegisterType(this, inst->VRegB_23x());
    if (array_type.IsZeroOrNull()) {
      // Null array class; this code path will fail at runtime. Infer a merge-able type from the
      // instruction type.
      if (!is_primitive) {
        work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), reg_types_.Null());
      } else if (insn_type.IsInteger()) {
        // Pick a non-zero constant (to distinguish with null) that can fit in any primitive.
        // We cannot use 'insn_type' as it could be a float array or an int array.
        work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), DetermineCat1Constant(1));
      } else if (insn_type.IsCategory1Types()) {
        // Category 1
        // The 'insn_type' is exactly the type we need.
        work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), insn_type);
      } else {
        // Category 2
        work_line_->SetRegisterTypeWide(inst->VRegA_23x(),
                                        reg_types_.FromCat2ConstLo(0, false),
                                        reg_types_.FromCat2ConstHi(0, false));
      }
    } else if (!array_type.IsArrayTypes()) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "not array type " << array_type << " with aget";
    } else if (array_type.IsUnresolvedMergedReference()) {
      // Unresolved array types must be reference array types.
      if (is_primitive) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "reference array type " << array_type
                    << " source for category 1 aget";
      } else {
        Fail(VERIFY_ERROR_NO_CLASS) << "cannot verify aget for " << array_type
            << " because of missing class";
        // Approximate with java.lang.Object[].
        work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(),
                                                    reg_types_.JavaLangObject(false));
      }
    } else {
      /* verify the class */
      const RegType& component_type = reg_types_.GetComponentType(array_type, class_loader_);
      if (!component_type.IsReferenceTypes() && !is_primitive) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "primitive array type " << array_type
            << " source for aget-object";
      } else if (component_type.IsNonZeroReferenceTypes() && is_primitive) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "reference array type " << array_type
            << " source for category 1 aget";
      } else if (is_primitive && !insn_type.Equals(component_type) &&
                 !((insn_type.IsInteger() && component_type.IsFloat()) ||
                 (insn_type.IsLong() && component_type.IsDouble()))) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "array type " << array_type
            << " incompatible with aget of type " << insn_type;
      } else {
        // Use knowledge of the field type which is stronger than the type inferred from the
        // instruction, which can't differentiate object types and ints from floats, longs from
        // doubles.
        if (!component_type.IsLowHalf()) {
          work_line_->SetRegisterType<LockOp::kClear>(inst->VRegA_23x(), component_type);
        } else {
          work_line_->SetRegisterTypeWide(inst->VRegA_23x(), component_type,
                                          component_type.HighHalf(&reg_types_));
        }
      }
    }
  }
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::VerifyPrimitivePut(const RegType& target_type,
                                                        const RegType& insn_type,
                                                        const uint32_t vregA) {
  // Primitive assignability rules are weaker than regular assignability rules.
  bool instruction_compatible;
  bool value_compatible;
  const RegType& value_type = work_line_->GetRegisterType(this, vregA);
  if (target_type.IsIntegralTypes()) {
    instruction_compatible = target_type.Equals(insn_type);
    value_compatible = value_type.IsIntegralTypes();
  } else if (target_type.IsFloat()) {
    instruction_compatible = insn_type.IsInteger();  // no put-float, so expect put-int
    value_compatible = value_type.IsFloatTypes();
  } else if (target_type.IsLong()) {
    instruction_compatible = insn_type.IsLong();
    // Additional register check: this is not checked statically (as part of VerifyInstructions),
    // as target_type depends on the resolved type of the field.
    if (instruction_compatible && work_line_->NumRegs() > vregA + 1) {
      const RegType& value_type_hi = work_line_->GetRegisterType(this, vregA + 1);
      value_compatible = value_type.IsLongTypes() && value_type.CheckWidePair(value_type_hi);
    } else {
      value_compatible = false;
    }
  } else if (target_type.IsDouble()) {
    instruction_compatible = insn_type.IsLong();  // no put-double, so expect put-long
    // Additional register check: this is not checked statically (as part of VerifyInstructions),
    // as target_type depends on the resolved type of the field.
    if (instruction_compatible && work_line_->NumRegs() > vregA + 1) {
      const RegType& value_type_hi = work_line_->GetRegisterType(this, vregA + 1);
      value_compatible = value_type.IsDoubleTypes() && value_type.CheckWidePair(value_type_hi);
    } else {
      value_compatible = false;
    }
  } else {
    instruction_compatible = false;  // reference with primitive store
    value_compatible = false;  // unused
  }
  if (!instruction_compatible) {
    // This is a global failure rather than a class change failure as the instructions and
    // the descriptors for the type should have been consistent within the same file at
    // compile time.
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "put insn has type '" << insn_type
        << "' but expected type '" << target_type << "'";
    return;
  }
  if (!value_compatible) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected value in v" << vregA
        << " of type " << value_type << " but expected " << target_type << " for put";
    return;
  }
}

template <bool kVerifierDebug>
void MethodVerifier<kVerifierDebug>::VerifyAPut(const Instruction* inst,
                                                const RegType& insn_type,
                                                bool is_primitive) {
  const RegType& index_type = work_line_->GetRegisterType(this, inst->VRegC_23x());
  if (!index_type.IsArrayIndexTypes()) {
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "Invalid reg type for array index (" << index_type << ")";
  } else {
    const RegType& array_type = work_line_->GetRegisterType(this, inst->VRegB_23x());
    if (array_type.IsZeroOrNull()) {
      // Null array type; this code path will fail at runtime.
      // Still check that the given value matches the instruction's type.
      // Note: this is, as usual, complicated by the fact the the instruction isn't fully typed
      //       and fits multiple register types.
      const RegType* modified_reg_type = &insn_type;
      if ((modified_reg_type == &reg_types_.Integer()) ||
          (modified_reg_type == &reg_types_.LongLo())) {
        // May be integer or float | long or double. Overwrite insn_type accordingly.
        const RegType& value_type = work_line_->GetRegisterType(this, inst->VRegA_23x());
        if (modified_reg_type == &reg_types_.Integer()) {
          if (&value_type == &reg_types_.Float()) {
            modified_reg_type = &value_type;
          }
        } else {
          if (&value_type == &reg_types_.DoubleLo()) {
            modified_reg_type = &value_type;
          }
        }
      }
      work_line_->VerifyRegisterType(this, inst->VRegA_23x(), *modified_reg_type);
    } else if (!array_type.IsArrayTypes()) {
      Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "not array type " << array_type << " with aput";
    } else if (array_type.IsUnresolvedMergedReference()) {
      // Unresolved array types must be reference array types.
      if (is_primitive) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "put insn has type '" << insn_type
                                          << "' but unresolved type '" << array_type << "'";
      } else {
        Fail(VERIFY_ERROR_NO_CLASS) << "cannot verify aput for " << array_type
                                    << " because of missing class";
      }
    } else {
      const RegType& component_type = reg_types_.GetComponentType(array_type, class_loader_);
      const uint32_t vregA = inst->VRegA_23x();
      if (is_primitive) {
        VerifyPrimitivePut(component_type, insn_type, vregA);
      } else {
        if (!component_type.IsReferenceTypes()) {
          Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "primitive array type " << array_type
              << " source for aput-object";
        } else {
          // The instruction agrees with the type of array, confirm the value to be stored does too
          // Note: we use the instruction type (rather than the component type) for aput-object as
          // incompatible classes will be caught at runtime as an array store exception
          work_line_->VerifyRegisterType(this, vregA, insn_type);
        }
      }
    }
  }
}

template <bool kVerifierDebug>
ArtField* MethodVerifier<kVerifierDebug>::GetStaticField(int field_idx) {
  const dex::FieldId& field_id = dex_file_->GetFieldId(field_idx);
  // Check access to class
  const RegType& klass_type = ResolveClass<CheckAccess::kYes>(field_id.class_idx_);
  if (klass_type.IsConflict()) {  // bad class
    AppendToLastFailMessage(StringPrintf(" in attempt to access static field %d (%s) in %s",
                                         field_idx, dex_file_->GetFieldName(field_id),
                                         dex_file_->GetFieldDeclaringClassDescriptor(field_id)));
    return nullptr;
  }
  if (klass_type.IsUnresolvedTypes()) {
    // Accessibility checks depend on resolved fields.
    DCHECK(klass_type.Equals(GetDeclaringClass()) ||
           !failures_.empty() ||
           IsSdkVersionSetAndLessThan(api_level_, SdkVersion::kP));

    return nullptr;  // Can't resolve Class so no more to do here, will do checking at runtime.
  }
  ClassLinker* class_linker = GetClassLinker();
  ArtField* field = class_linker->ResolveFieldJLS(field_idx, dex_cache_, class_loader_);

  if (field == nullptr) {
    VLOG(verifier) << "Unable to resolve static field " << field_idx << " ("
              << dex_file_->GetFieldName(field_id) << ") in "
              << dex_file_->GetFieldDeclaringClassDescriptor(field_id);
    DCHECK(self_->IsExceptionPending());
    self_->ClearException();
    return nullptr;
  } else if (!GetDeclaringClass().CanAccessMember(field->GetDeclaringClass(),
                                                  field->GetAccessFlags())) {
    Fail(VERIFY_ERROR_ACCESS_FIELD) << "cannot access static field " << field->PrettyField()
                                    << " from " << GetDeclaringClass();
    return nullptr;
  } else if (!field->IsStatic()) {
    Fail(VERIFY_ERROR_CLASS_CHANGE) << "expected field " << field->PrettyField() << " to be static";
    return nullptr;
  }
  return field;
}

template <bool kVerifierDebug>
ArtField* MethodVerifier<kVerifierDebug>::GetInstanceField(const RegType& obj_type, int field_idx) {
  if (!obj_type.IsZeroOrNull() && !obj_type.IsReferenceTypes()) {
    // Trying to read a field from something that isn't a reference.
    Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "instance field access on object that has "
        << "non-reference type " << obj_type;
    return nullptr;
  }
  const dex::FieldId& field_id = dex_file_->GetFieldId(field_idx);
  // Check access to class.
  const RegType& klass_type = ResolveClass<CheckAccess::kYes>(field_id.class_idx_);
  if (klass_type.IsConflict()) {
    AppendToLastFailMessage(StringPrintf(" in attempt to access instance field %d (%s) in %s",
                                         field_idx, dex_file_->GetFieldName(field_id),
                                         dex_file_->GetFieldDeclaringClassDescriptor(field_id)));
    return nullptr;
  }
  if (klass_type.IsUnresolvedTypes()) {
    // Accessibility checks depend on resolved fields.
    DCHECK(klass_type.Equals(GetDeclaringClass()) ||
           !failures_.empty() ||
           IsSdkVersionSetAndLessThan(api_level_, SdkVersion::kP));

    return nullptr;  // Can't resolve Class so no more to do here
  }
  ClassLinker* class_linker = GetClassLinker();
  ArtField* field = class_linker->ResolveFieldJLS(field_idx, dex_cache_, class_loader_);

  if (field == nullptr) {
    VLOG(verifier) << "Unable to resolve instance field " << field_idx << " ("
              << dex_file_->GetFieldName(field_id) << ") in "
              << dex_file_->GetFieldDeclaringClassDescriptor(field_id);
    DCHECK(self_->IsExceptionPending());
    self_->ClearException();
    return nullptr;
  } else if (obj_type.IsZeroOrNull()) {
    // Cannot infer and check type, however, access will cause null pointer exception.
    // Fall through into a few last soft failure checks below.
  } else {
    std::string temp;
    ObjPtr<mirror::Class> klass = field->GetDeclaringClass();
    const RegType& field_klass =
        FromClass(klass->GetDescriptor(&temp), klass, klass->CannotBeAssignedFromOtherTypes());
    if (obj_type.IsUninitializedTypes()) {
      // Field accesses through uninitialized references are only allowable for constructors where
      // the field is declared in this class.
      // Note: this IsConstructor check is technically redundant, as UninitializedThis should only
      //       appear in constructors.
      if (!obj_type.IsUninitializedThisReference() ||
          !IsConstructor() ||
          !field_klass.Equals(GetDeclaringClass())) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "cannot access instance field " << field->PrettyField()
                                          << " of a not fully initialized object within the context"
                                          << " of " << dex_file_->PrettyMethod(dex_method_idx_);
        return nullptr;
      }
    } else if (!field_klass.IsAssignableFrom(obj_type, this)) {
      // Trying to access C1.field1 using reference of type C2, which is neither C1 or a sub-class
      // of C1. For resolution to occur the declared class of the field must be compatible with
      // obj_type, we've discovered this wasn't so, so report the field didn't exist.
      VerifyError type;
      bool is_aot = IsAotMode();
      if (is_aot && (field_klass.IsUnresolvedTypes() || obj_type.IsUnresolvedTypes())) {
        // Compiler & unresolved types involved, retry at runtime.
        type = VerifyError::VERIFY_ERROR_UNRESOLVED_TYPE_CHECK;
      } else {
        // Classes known (resolved; and thus assignability check is precise), or we are at runtime
        // and still missing classes. This is a hard failure.
        type = VerifyError::VERIFY_ERROR_BAD_CLASS_HARD;
      }
      Fail(type) << "cannot access instance field " << field->PrettyField()
                 << " from object of type " << obj_type;
      return nullptr;
    }
  }

  // Few last soft failure checks.
  if (!GetDeclaringClass().CanAccessMember(field->GetDeclaringClass(),
                                           field->GetAccessFlags())) {
    Fail(VERIFY_ERROR_ACCESS_FIELD) << "cannot access instance field " << field->PrettyField()
                                    << " from " << GetDeclaringClass();
    return nullptr;
  } else if (field->IsStatic()) {
    Fail(VERIFY_ERROR_CLASS_CHANGE) << "expected field " << field->PrettyField()
                                    << " to not be static";
    return nullptr;
  }

  return field;
}

template <bool kVerifierDebug>
template <FieldAccessType kAccType>
void MethodVerifier<kVerifierDebug>::VerifyISFieldAccess(const Instruction* inst,
                                                         const RegType& insn_type,
                                                         bool is_primitive,
                                                         bool is_static) {
  uint32_t field_idx = GetFieldIdxOfFieldAccess(inst, is_static);
  ArtField* field;
  if (is_static) {
    field = GetStaticField(field_idx);
  } else {
    const RegType& object_type = work_line_->GetRegisterType(this, inst->VRegB_22c());

    // One is not allowed to access fields on uninitialized references, except to write to
    // fields in the constructor (before calling another constructor).
    // GetInstanceField does an assignability check which will fail for uninitialized types.
    // We thus modify the type if the uninitialized reference is a "this" reference (this also
    // checks at the same time that we're verifying a constructor).
    bool should_adjust = (kAccType == FieldAccessType::kAccPut) &&
                         (object_type.IsUninitializedThisReference() ||
                          object_type.IsUnresolvedAndUninitializedThisReference());
    const RegType& adjusted_type = should_adjust
                                       ? GetRegTypeCache()->FromUninitialized(object_type)
                                       : object_type;
    field = GetInstanceField(adjusted_type, field_idx);
    if (UNLIKELY(flags_.have_pending_hard_failure_)) {
      return;
    }
    if (should_adjust) {
      bool illegal_field_access = false;
      if (field == nullptr) {
        const dex::FieldId& field_id = dex_file_->GetFieldId(field_idx);
        if (field_id.class_idx_ != GetClassDef().class_idx_) {
          illegal_field_access = true;
        } else {
          ClassAccessor accessor(*dex_file_, GetClassDef());
          illegal_field_access = (accessor.GetInstanceFields().end() ==
              std::find_if(accessor.GetInstanceFields().begin(),
                           accessor.GetInstanceFields().end(),
                           [field_idx] (const ClassAccessor::Field& f) {
                             return f.GetIndex() == field_idx;
                           }));
        }
      } else if (field->GetDeclaringClass() != GetDeclaringClass().GetClass()) {
        illegal_field_access = true;
      }
      if (illegal_field_access) {
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "cannot access instance field "
                                          << dex_file_->PrettyField(field_idx)
                                          << " of a not fully initialized "
                                          << "object within the context of "
                                          << dex_file_->PrettyMethod(dex_method_idx_);
        return;
      }
    }
  }
  const RegType* field_type = nullptr;
  if (field != nullptr) {
    if (kAccType == FieldAccessType::kAccPut) {
      if (field->IsFinal() && field->GetDeclaringClass() != GetDeclaringClass().GetClass()) {
        Fail(VERIFY_ERROR_ACCESS_FIELD) << "cannot modify final field " << field->PrettyField()
                                        << " from other class " << GetDeclaringClass();
        // Keep hunting for possible hard fails.
      }
    }

    ObjPtr<mirror::Class> field_type_class =
        CanLoadClasses() ? field->ResolveType() : field->LookupResolvedType();
    if (field_type_class != nullptr) {
      field_type = &FromClass(field->GetTypeDescriptor(),
                              field_type_class,
                              field_type_class->CannotBeAssignedFromOtherTypes());
    } else {
      DCHECK_IMPLIES(CanLoadClasses(), self_->IsExceptionPending());
      self_->ClearException();
    }
  } else if (IsSdkVersionSetAndAtLeast(api_level_, SdkVersion::kP)) {
    // If we don't have the field (it seems we failed resolution) and this is a PUT, we need to
    // redo verification at runtime as the field may be final, unless the field id shows it's in
    // the same class.
    //
    // For simplicity, it is OK to not distinguish compile-time vs runtime, and post this an
    // ACCESS_FIELD failure at runtime. This has the same effect as NO_FIELD - punting the class
    // to the access-checks interpreter.
    //
    // Note: see b/34966607. This and above may be changed in the future.
    if (kAccType == FieldAccessType::kAccPut) {
      const dex::FieldId& field_id = dex_file_->GetFieldId(field_idx);
      const char* field_class_descriptor = dex_file_->GetFieldDeclaringClassDescriptor(field_id);
      const RegType* field_class_type =
          &reg_types_.FromDescriptor(class_loader_, field_class_descriptor);
      if (!field_class_type->Equals(GetDeclaringClass())) {
        Fail(VERIFY_ERROR_ACCESS_FIELD) << "could not check field put for final field modify of "
                                        << field_class_descriptor
                                        << "."
                                        << dex_file_->GetFieldName(field_id)
                                        << " from other class "
                                        << GetDeclaringClass();
      }
    }
  }
  if (field_type == nullptr) {
    const dex::FieldId& field_id = dex_file_->GetFieldId(field_idx);
    const char* descriptor = dex_file_->GetFieldTypeDescriptor(field_id);
    field_type = &reg_types_.FromDescriptor(class_loader_, descriptor);
  }
  DCHECK(field_type != nullptr);
  const uint32_t vregA = (is_static) ? inst->VRegA_21c() : inst->VRegA_22c();
  static_assert(kAccType == FieldAccessType::kAccPut || kAccType == FieldAccessType::kAccGet,
                "Unexpected third access type");
  if (kAccType == FieldAccessType::kAccPut) {
    // sput or iput.
    if (is_primitive) {
      VerifyPrimitivePut(*field_type, insn_type, vregA);
    } else {
      DCHECK(insn_type.IsJavaLangObject());
      if (!insn_type.IsAssignableFrom(*field_type, this)) {
        DCHECK(!field_type->IsReferenceTypes());
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected field " << ArtField::PrettyField(field)
                                          << " to be compatible with type '" << insn_type
                                          << "' but found type '" << *field_type
                                          << "' in put-object";
        return;
      }
      work_line_->VerifyRegisterType(this, vregA, *field_type);
    }
  } else if (kAccType == FieldAccessType::kAccGet) {
    // sget or iget.
    if (is_primitive) {
      if (field_type->Equals(insn_type) ||
          (field_type->IsFloat() && insn_type.IsInteger()) ||
          (field_type->IsDouble() && insn_type.IsLong())) {
        // expected that read is of the correct primitive type or that int reads are reading
        // floats or long reads are reading doubles
      } else {
        // This is a global failure rather than a class change failure as the instructions and
        // the descriptors for the type should have been consistent within the same file at
        // compile time
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected field " << ArtField::PrettyField(field)
                                          << " to be of type '" << insn_type
                                          << "' but found type '" << *field_type << "' in get";
        return;
      }
    } else {
      DCHECK(insn_type.IsJavaLangObject());
      if (!insn_type.IsAssignableFrom(*field_type, this)) {
        DCHECK(!field_type->IsReferenceTypes());
        Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "expected field " << ArtField::PrettyField(field)
                                          << " to be compatible with type '" << insn_type
                                          << "' but found type '" << *field_type
                                          << "' in get-object";
        return;
      }
    }
    if (!field_type->IsLowHalf()) {
      work_line_->SetRegisterType<LockOp::kClear>(vregA, *field_type);
    } else {
      work_line_->SetRegisterTypeWide(vregA, *field_type, field_type->HighHalf(&reg_types_));
    }
  } else {
    LOG(FATAL) << "Unexpected case.";
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::UpdateRegisters(uint32_t next_insn,
                                                     RegisterLine* merge_line,
                                                     bool update_merge_line) {
  bool changed = true;
  RegisterLine* target_line = reg_table_.GetLine(next_insn);
  if (!GetInstructionFlags(next_insn).IsVisitedOrChanged()) {
    /*
     * We haven't processed this instruction before, and we haven't touched the registers here, so
     * there's nothing to "merge". Copy the registers over and mark it as changed. (This is the
     * only way a register can transition out of "unknown", so this is not just an optimization.)
     */
    target_line->CopyFromLine(merge_line);
    if (GetInstructionFlags(next_insn).IsReturn()) {
      // Verify that the monitor stack is empty on return.
      merge_line->VerifyMonitorStackEmpty(this);

      // For returns we only care about the operand to the return, all other registers are dead.
      // Initialize them as conflicts so they don't add to GC and deoptimization information.
      const Instruction* ret_inst = &code_item_accessor_.InstructionAt(next_insn);
      AdjustReturnLine(this, ret_inst, target_line);
      // Directly bail if a hard failure was found.
      if (flags_.have_pending_hard_failure_) {
        return false;
      }
    }
  } else {
    RegisterLineArenaUniquePtr copy;
    if (kVerifierDebug) {
      copy.reset(RegisterLine::Create(target_line->NumRegs(), allocator_, GetRegTypeCache()));
      copy->CopyFromLine(target_line);
    }
    changed = target_line->MergeRegisters(this, merge_line);
    if (flags_.have_pending_hard_failure_) {
      return false;
    }
    if (kVerifierDebug && changed) {
      LogVerifyInfo() << "Merging at [" << reinterpret_cast<void*>(work_insn_idx_) << "]"
                      << " to [" << reinterpret_cast<void*>(next_insn) << "]: " << "\n"
                      << copy->Dump(this) << "  MERGE\n"
                      << merge_line->Dump(this) << "  ==\n"
                      << target_line->Dump(this);
    }
    if (update_merge_line && changed) {
      merge_line->CopyFromLine(target_line);
    }
  }
  if (changed) {
    GetModifiableInstructionFlags(next_insn).SetChanged();
  }
  return true;
}

template <bool kVerifierDebug>
const RegType& MethodVerifier<kVerifierDebug>::GetMethodReturnType() {
  if (return_type_ == nullptr) {
    const dex::MethodId& method_id = dex_file_->GetMethodId(dex_method_idx_);
    const dex::ProtoId& proto_id = dex_file_->GetMethodPrototype(method_id);
    dex::TypeIndex return_type_idx = proto_id.return_type_idx_;
    const char* descriptor = dex_file_->GetTypeDescriptor(dex_file_->GetTypeId(return_type_idx));
    return_type_ = &reg_types_.FromDescriptor(class_loader_, descriptor);
  }
  return *return_type_;
}

template <bool kVerifierDebug>
const RegType& MethodVerifier<kVerifierDebug>::DetermineCat1Constant(int32_t value) {
  // Imprecise constant type.
  if (value < -32768) {
    return reg_types_.IntConstant();
  } else if (value < -128) {
    return reg_types_.ShortConstant();
  } else if (value < 0) {
    return reg_types_.ByteConstant();
  } else if (value == 0) {
    return reg_types_.Zero();
  } else if (value == 1) {
    return reg_types_.One();
  } else if (value < 128) {
    return reg_types_.PosByteConstant();
  } else if (value < 32768) {
    return reg_types_.PosShortConstant();
  } else if (value < 65536) {
    return reg_types_.CharConstant();
  } else {
    return reg_types_.IntConstant();
  }
}

template <bool kVerifierDebug>
bool MethodVerifier<kVerifierDebug>::PotentiallyMarkRuntimeThrow() {
  if (IsAotMode() || IsSdkVersionSetAndAtLeast(api_level_, SdkVersion::kS_V2)) {
    return false;
  }
  // Compatibility mode: we treat the following code unreachable and the verifier
  // will not analyze it.
  // The verifier may fail before we touch any instruction, for the signature of a method. So
  // add a check.
  if (work_insn_idx_ < dex::kDexNoIndex) {
    const Instruction& inst = code_item_accessor_.InstructionAt(work_insn_idx_);
    Instruction::Code opcode = inst.Opcode();
    if (opcode == Instruction::MOVE_EXCEPTION) {
      // This is an unreachable handler. The instruction doesn't throw, but we
      // mark the method as having a pending runtime throw failure so that
      // the compiler does not try to compile it.
      Fail(VERIFY_ERROR_RUNTIME_THROW, /* pending_exc= */ false);
      return true;
    }
    // How to handle runtime failures for instructions that are not flagged kThrow.
    if ((Instruction::FlagsOf(opcode) & Instruction::kThrow) == 0 &&
        !impl::IsCompatThrow(opcode) &&
        GetInstructionFlags(work_insn_idx_).IsInTry()) {
      if (Runtime::Current()->IsVerifierMissingKThrowFatal()) {
        LOG(FATAL) << "Unexpected throw: " << std::hex << work_insn_idx_ << " " << opcode;
        UNREACHABLE();
      }
      // We need to save the work_line if the instruction wasn't throwing before. Otherwise
      // we'll try to merge garbage.
      // Note: this assumes that Fail is called before we do any work_line modifications.
      saved_line_->CopyFromLine(work_line_.get());
    }
  }
  flags_.have_pending_runtime_throw_failure_ = true;
  return true;
}

}  // namespace
}  // namespace impl

MethodVerifier::MethodVerifier(Thread* self,
                               ClassLinker* class_linker,
                               ArenaPool* arena_pool,
                               VerifierDeps* verifier_deps,
                               const DexFile* dex_file,
                               const dex::ClassDef& class_def,
                               const dex::CodeItem* code_item,
                               uint32_t dex_method_idx,
                               bool can_load_classes,
                               bool allow_thread_suspension,
                               bool aot_mode)
    : self_(self),
      arena_stack_(arena_pool),
      allocator_(&arena_stack_),
      reg_types_(self, class_linker, can_load_classes, allocator_, allow_thread_suspension),
      reg_table_(allocator_),
      work_insn_idx_(dex::kDexNoIndex),
      dex_method_idx_(dex_method_idx),
      dex_file_(dex_file),
      class_def_(class_def),
      code_item_accessor_(*dex_file, code_item),
      // TODO: make it designated initialization when we compile as C++20.
      flags_({false, false}),
      const_flags_({aot_mode, can_load_classes}),
      encountered_failure_types_(0),
      verifier_deps_(verifier_deps),
      link_(nullptr) {
}

MethodVerifier::~MethodVerifier() {
  STLDeleteElements(&failure_messages_);
}

MethodVerifier::FailureData MethodVerifier::VerifyMethod(Thread* self,
                                                         ClassLinker* class_linker,
                                                         ArenaPool* arena_pool,
                                                         VerifierDeps* verifier_deps,
                                                         uint32_t method_idx,
                                                         const DexFile* dex_file,
                                                         Handle<mirror::DexCache> dex_cache,
                                                         Handle<mirror::ClassLoader> class_loader,
                                                         const dex::ClassDef& class_def,
                                                         const dex::CodeItem* code_item,
                                                         uint32_t method_access_flags,
                                                         HardFailLogMode log_level,
                                                         uint32_t api_level,
                                                         bool aot_mode,
                                                         std::string* hard_failure_msg) {
  if (VLOG_IS_ON(verifier_debug)) {
    return VerifyMethod<true>(self,
                              class_linker,
                              arena_pool,
                              verifier_deps,
                              method_idx,
                              dex_file,
                              dex_cache,
                              class_loader,
                              class_def,
                              code_item,
                              method_access_flags,
                              log_level,
                              api_level,
                              aot_mode,
                              hard_failure_msg);
  } else {
    return VerifyMethod<false>(self,
                               class_linker,
                               arena_pool,
                               verifier_deps,
                               method_idx,
                               dex_file,
                               dex_cache,
                               class_loader,
                               class_def,
                               code_item,
                               method_access_flags,
                               log_level,
                               api_level,
                               aot_mode,
                               hard_failure_msg);
  }
}

// Return whether the runtime knows how to execute a method without needing to
// re-verify it at runtime (and therefore save on first use of the class).
// The AOT/JIT compiled code is not affected.
static inline bool CanRuntimeHandleVerificationFailure(uint32_t encountered_failure_types) {
  constexpr uint32_t unresolved_mask =
      verifier::VerifyError::VERIFY_ERROR_UNRESOLVED_TYPE_CHECK |
      verifier::VerifyError::VERIFY_ERROR_NO_CLASS |
      verifier::VerifyError::VERIFY_ERROR_CLASS_CHANGE |
      verifier::VerifyError::VERIFY_ERROR_INSTANTIATION |
      verifier::VerifyError::VERIFY_ERROR_ACCESS_CLASS |
      verifier::VerifyError::VERIFY_ERROR_ACCESS_FIELD |
      verifier::VerifyError::VERIFY_ERROR_NO_METHOD |
      verifier::VerifyError::VERIFY_ERROR_ACCESS_METHOD |
      verifier::VerifyError::VERIFY_ERROR_RUNTIME_THROW;
  return (encountered_failure_types & (~unresolved_mask)) == 0;
}

template <bool kVerifierDebug>
MethodVerifier::FailureData MethodVerifier::VerifyMethod(Thread* self,
                                                         ClassLinker* class_linker,
                                                         ArenaPool* arena_pool,
                                                         VerifierDeps* verifier_deps,
                                                         uint32_t method_idx,
                                                         const DexFile* dex_file,
                                                         Handle<mirror::DexCache> dex_cache,
                                                         Handle<mirror::ClassLoader> class_loader,
                                                         const dex::ClassDef& class_def,
                                                         const dex::CodeItem* code_item,
                                                         uint32_t method_access_flags,
                                                         HardFailLogMode log_level,
                                                         uint32_t api_level,
                                                         bool aot_mode,
                                                         std::string* hard_failure_msg) {
  MethodVerifier::FailureData result;
  uint64_t start_ns = kTimeVerifyMethod ? NanoTime() : 0;

  impl::MethodVerifier<kVerifierDebug> verifier(self,
                                                class_linker,
                                                arena_pool,
                                                verifier_deps,
                                                dex_file,
                                                code_item,
                                                method_idx,
                                                /* can_load_classes= */ true,
                                                /* allow_thread_suspension= */ true,
                                                aot_mode,
                                                dex_cache,
                                                class_loader,
                                                class_def,
                                                method_access_flags,
                                                /* verify to dump */ false,
                                                api_level);
  if (verifier.Verify()) {
    // Verification completed, however failures may be pending that didn't cause the verification
    // to hard fail.
    CHECK(!verifier.flags_.have_pending_hard_failure_);

    if (verifier.failures_.size() != 0) {
      if (VLOG_IS_ON(verifier)) {
        verifier.DumpFailures(VLOG_STREAM(verifier) << "Soft verification failures in "
                                                    << dex_file->PrettyMethod(method_idx) << "\n");
      }
      if (kVerifierDebug) {
        LOG(INFO) << verifier.info_messages_.str();
        verifier.Dump(LOG_STREAM(INFO));
      }
      if (CanRuntimeHandleVerificationFailure(verifier.encountered_failure_types_)) {
        if (verifier.encountered_failure_types_ & VERIFY_ERROR_UNRESOLVED_TYPE_CHECK) {
          result.kind = FailureKind::kTypeChecksFailure;
        } else {
          result.kind = FailureKind::kAccessChecksFailure;
        }
      } else {
        result.kind = FailureKind::kSoftFailure;
      }
    }
  } else {
    // Bad method data.
    CHECK_NE(verifier.failures_.size(), 0U);
    CHECK(verifier.flags_.have_pending_hard_failure_);
    if (VLOG_IS_ON(verifier)) {
      log_level = std::max(HardFailLogMode::kLogVerbose, log_level);
    }
    if (log_level >= HardFailLogMode::kLogVerbose) {
      LogSeverity severity;
      switch (log_level) {
        case HardFailLogMode::kLogVerbose:
          severity = LogSeverity::VERBOSE;
          break;
        case HardFailLogMode::kLogWarning:
          severity = LogSeverity::WARNING;
          break;
        case HardFailLogMode::kLogInternalFatal:
          severity = LogSeverity::FATAL_WITHOUT_ABORT;
          break;
        default:
          LOG(FATAL) << "Unsupported log-level " << static_cast<uint32_t>(log_level);
          UNREACHABLE();
      }
      verifier.DumpFailures(LOG_STREAM(severity) << "Verification error in "
                                                 << dex_file->PrettyMethod(method_idx)
                                                 << "\n");
    }
    if (hard_failure_msg != nullptr) {
      CHECK(!verifier.failure_messages_.empty());
      *hard_failure_msg =
          verifier.failure_messages_[verifier.failure_messages_.size() - 1]->str();
    }
    result.kind = FailureKind::kHardFailure;

    if (kVerifierDebug || VLOG_IS_ON(verifier)) {
      LOG(ERROR) << verifier.info_messages_.str();
      verifier.Dump(LOG_STREAM(ERROR));
    }
    // Under verifier-debug, dump the complete log into the error message.
    if (kVerifierDebug && hard_failure_msg != nullptr) {
      hard_failure_msg->append("\n");
      hard_failure_msg->append(verifier.info_messages_.str());
      hard_failure_msg->append("\n");
      std::ostringstream oss;
      verifier.Dump(oss);
      hard_failure_msg->append(oss.str());
    }
  }
  if (kTimeVerifyMethod) {
    uint64_t duration_ns = NanoTime() - start_ns;
    if (duration_ns > MsToNs(Runtime::Current()->GetVerifierLoggingThresholdMs())) {
      double bytecodes_per_second =
          verifier.code_item_accessor_.InsnsSizeInCodeUnits() / (duration_ns * 1e-9);
      LOG(WARNING) << "Verification of " << dex_file->PrettyMethod(method_idx)
                   << " took " << PrettyDuration(duration_ns)
                   << (impl::IsLargeMethod(verifier.CodeItem()) ? " (large method)" : "")
                   << " (" << StringPrintf("%.2f", bytecodes_per_second) << " bytecodes/s)"
                   << " (" << verifier.allocator_.ApproximatePeakBytes()
                   << "B approximate peak alloc)";
    }
  }
  result.types = verifier.encountered_failure_types_;
  return result;
}

MethodVerifier* MethodVerifier::CalculateVerificationInfo(
      Thread* self,
      ArtMethod* method,
      Handle<mirror::DexCache> dex_cache,
      Handle<mirror::ClassLoader> class_loader,
      uint32_t dex_pc) {
  std::unique_ptr<impl::MethodVerifier<false>> verifier(
      new impl::MethodVerifier<false>(self,
                                      Runtime::Current()->GetClassLinker(),
                                      Runtime::Current()->GetArenaPool(),
                                      /* verifier_deps= */ nullptr,
                                      method->GetDexFile(),
                                      method->GetCodeItem(),
                                      method->GetDexMethodIndex(),
                                      /* can_load_classes= */ false,
                                      /* allow_thread_suspension= */ false,
                                      Runtime::Current()->IsAotCompiler(),
                                      dex_cache,
                                      class_loader,
                                      *method->GetDeclaringClass()->GetClassDef(),
                                      method->GetAccessFlags(),
                                      /* verify_to_dump= */ false,
                                      // Just use the verifier at the current skd-version.
                                      // This might affect what soft-verifier errors are reported.
                                      // Callers can then filter out relevant errors if needed.
                                      Runtime::Current()->GetTargetSdkVersion()));
  verifier->interesting_dex_pc_ = dex_pc;
  verifier->Verify();
  if (VLOG_IS_ON(verifier)) {
    verifier->DumpFailures(VLOG_STREAM(verifier));
    VLOG(verifier) << verifier->info_messages_.str();
    verifier->Dump(VLOG_STREAM(verifier));
  }
  if (verifier->flags_.have_pending_hard_failure_) {
    return nullptr;
  } else {
    return verifier.release();
  }
}

MethodVerifier* MethodVerifier::VerifyMethodAndDump(Thread* self,
                                                    VariableIndentationOutputStream* vios,
                                                    uint32_t dex_method_idx,
                                                    const DexFile* dex_file,
                                                    Handle<mirror::DexCache> dex_cache,
                                                    Handle<mirror::ClassLoader> class_loader,
                                                    const dex::ClassDef& class_def,
                                                    const dex::CodeItem* code_item,
                                                    uint32_t method_access_flags,
                                                    uint32_t api_level) {
  impl::MethodVerifier<false>* verifier = new impl::MethodVerifier<false>(
      self,
      Runtime::Current()->GetClassLinker(),
      Runtime::Current()->GetArenaPool(),
      /* verifier_deps= */ nullptr,
      dex_file,
      code_item,
      dex_method_idx,
      /* can_load_classes= */ true,
      /* allow_thread_suspension= */ true,
      Runtime::Current()->IsAotCompiler(),
      dex_cache,
      class_loader,
      class_def,
      method_access_flags,
      /* verify_to_dump= */ true,
      api_level);
  verifier->Verify();
  verifier->DumpFailures(vios->Stream());
  vios->Stream() << verifier->info_messages_.str();
  // Only dump and return if no hard failures. Otherwise the verifier may be not fully initialized
  // and querying any info is dangerous/can abort.
  if (verifier->flags_.have_pending_hard_failure_) {
    delete verifier;
    return nullptr;
  } else {
    verifier->Dump(vios);
    return verifier;
  }
}

void MethodVerifier::FindLocksAtDexPc(
    ArtMethod* m,
    uint32_t dex_pc,
    std::vector<MethodVerifier::DexLockInfo>* monitor_enter_dex_pcs,
    uint32_t api_level) {
  StackHandleScope<2> hs(Thread::Current());
  Handle<mirror::DexCache> dex_cache(hs.NewHandle(m->GetDexCache()));
  Handle<mirror::ClassLoader> class_loader(hs.NewHandle(m->GetClassLoader()));
  impl::MethodVerifier<false> verifier(hs.Self(),
                                       Runtime::Current()->GetClassLinker(),
                                       Runtime::Current()->GetArenaPool(),
                                       /* verifier_deps= */ nullptr,
                                       m->GetDexFile(),
                                       m->GetCodeItem(),
                                       m->GetDexMethodIndex(),
                                       /* can_load_classes= */ false,
                                       /* allow_thread_suspension= */ false,
                                       Runtime::Current()->IsAotCompiler(),
                                       dex_cache,
                                       class_loader,
                                       m->GetClassDef(),
                                       m->GetAccessFlags(),
                                       /* verify_to_dump= */ false,
                                       api_level);
  verifier.interesting_dex_pc_ = dex_pc;
  verifier.monitor_enter_dex_pcs_ = monitor_enter_dex_pcs;
  verifier.FindLocksAtDexPc();
}

MethodVerifier* MethodVerifier::CreateVerifier(Thread* self,
                                               VerifierDeps* verifier_deps,
                                               const DexFile* dex_file,
                                               Handle<mirror::DexCache> dex_cache,
                                               Handle<mirror::ClassLoader> class_loader,
                                               const dex::ClassDef& class_def,
                                               const dex::CodeItem* code_item,
                                               uint32_t method_idx,
                                               uint32_t access_flags,
                                               bool can_load_classes,
                                               bool verify_to_dump,
                                               bool allow_thread_suspension,
                                               uint32_t api_level) {
  return new impl::MethodVerifier<false>(self,
                                         Runtime::Current()->GetClassLinker(),
                                         Runtime::Current()->GetArenaPool(),
                                         verifier_deps,
                                         dex_file,
                                         code_item,
                                         method_idx,
                                         can_load_classes,
                                         allow_thread_suspension,
                                         Runtime::Current()->IsAotCompiler(),
                                         dex_cache,
                                         class_loader,
                                         class_def,
                                         access_flags,
                                         verify_to_dump,
                                         api_level);
}

std::ostream& MethodVerifier::Fail(VerifyError error, bool pending_exc) {
  // Mark the error type as encountered.
  encountered_failure_types_ |= static_cast<uint32_t>(error);

  if (pending_exc) {
    switch (error) {
      case VERIFY_ERROR_NO_CLASS:
      case VERIFY_ERROR_UNRESOLVED_TYPE_CHECK:
      case VERIFY_ERROR_NO_METHOD:
      case VERIFY_ERROR_ACCESS_CLASS:
      case VERIFY_ERROR_ACCESS_FIELD:
      case VERIFY_ERROR_ACCESS_METHOD:
      case VERIFY_ERROR_INSTANTIATION:
      case VERIFY_ERROR_CLASS_CHANGE: {
        PotentiallyMarkRuntimeThrow();
        break;
      }

      case VERIFY_ERROR_LOCKING:
        PotentiallyMarkRuntimeThrow();
        // This will be reported to the runtime as a soft failure.
        break;

      // Hard verification failures at compile time will still fail at runtime, so the class is
      // marked as rejected to prevent it from being compiled.
      case VERIFY_ERROR_BAD_CLASS_HARD: {
        flags_.have_pending_hard_failure_ = true;
        break;
      }

      case VERIFY_ERROR_RUNTIME_THROW: {
        LOG(FATAL) << "UNREACHABLE";
      }
    }
  } else if (kIsDebugBuild) {
    CHECK_NE(error, VERIFY_ERROR_BAD_CLASS_HARD);
  }

  failures_.push_back(error);
  std::string location(StringPrintf("%s: [0x%X] ", dex_file_->PrettyMethod(dex_method_idx_).c_str(),
                                    work_insn_idx_));
  std::ostringstream* failure_message = new std::ostringstream(location, std::ostringstream::ate);
  failure_messages_.push_back(failure_message);
  return *failure_message;
}

ScopedNewLine MethodVerifier::LogVerifyInfo() {
  ScopedNewLine ret{info_messages_};
  ret << "VFY: " << dex_file_->PrettyMethod(dex_method_idx_)
      << '[' << reinterpret_cast<void*>(work_insn_idx_) << "] : ";
  return ret;
}

static FailureKind FailureKindMax(FailureKind fk1, FailureKind fk2) {
  static_assert(FailureKind::kNoFailure < FailureKind::kSoftFailure
                    && FailureKind::kSoftFailure < FailureKind::kHardFailure,
                "Unexpected FailureKind order");
  return std::max(fk1, fk2);
}

void MethodVerifier::FailureData::Merge(const MethodVerifier::FailureData& fd) {
  kind = FailureKindMax(kind, fd.kind);
  types |= fd.types;
}

}  // namespace verifier
}  // namespace art