runtime/interpreter/interpreter.cc

/*
 * Copyright (C) 2012 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 "interpreter.h"

#include <limits>

#include "common_throws.h"
#include "interpreter_common.h"
#include "mirror/string-inl.h"
#include "scoped_thread_state_change.h"
#include "ScopedLocalRef.h"
#include "stack.h"
#include "unstarted_runtime.h"
#include "mterp/mterp.h"
#include "jit/jit.h"
#include "jit/jit_code_cache.h"

namespace art {
namespace interpreter {

static void InterpreterJni(Thread* self, ArtMethod* method, const StringPiece& shorty,
                           Object* receiver, uint32_t* args, JValue* result)
    SHARED_REQUIRES(Locks::mutator_lock_) {
  // TODO: The following enters JNI code using a typedef-ed function rather than the JNI compiler,
  //       it should be removed and JNI compiled stubs used instead.
  ScopedObjectAccessUnchecked soa(self);
  if (method->IsStatic()) {
    if (shorty == "L") {
      typedef jobject (fntype)(JNIEnv*, jclass);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      jobject jresult;
      {
        ScopedThreadStateChange tsc(self, kNative);
        jresult = fn(soa.Env(), klass.get());
      }
      result->SetL(soa.Decode<Object*>(jresult));
    } else if (shorty == "V") {
      typedef void (fntype)(JNIEnv*, jclass);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      fn(soa.Env(), klass.get());
    } else if (shorty == "Z") {
      typedef jboolean (fntype)(JNIEnv*, jclass);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetZ(fn(soa.Env(), klass.get()));
    } else if (shorty == "BI") {
      typedef jbyte (fntype)(JNIEnv*, jclass, jint);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetB(fn(soa.Env(), klass.get(), args[0]));
    } else if (shorty == "II") {
      typedef jint (fntype)(JNIEnv*, jclass, jint);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetI(fn(soa.Env(), klass.get(), args[0]));
    } else if (shorty == "LL") {
      typedef jobject (fntype)(JNIEnv*, jclass, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg0(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[0])));
      jobject jresult;
      {
        ScopedThreadStateChange tsc(self, kNative);
        jresult = fn(soa.Env(), klass.get(), arg0.get());
      }
      result->SetL(soa.Decode<Object*>(jresult));
    } else if (shorty == "IIZ") {
      typedef jint (fntype)(JNIEnv*, jclass, jint, jboolean);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetI(fn(soa.Env(), klass.get(), args[0], args[1]));
    } else if (shorty == "ILI") {
      typedef jint (fntype)(JNIEnv*, jclass, jobject, jint);
      fntype* const fn = reinterpret_cast<fntype*>(const_cast<void*>(
          method->GetEntryPointFromJni()));
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg0(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[0])));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetI(fn(soa.Env(), klass.get(), arg0.get(), args[1]));
    } else if (shorty == "SIZ") {
      typedef jshort (fntype)(JNIEnv*, jclass, jint, jboolean);
      fntype* const fn =
          reinterpret_cast<fntype*>(const_cast<void*>(method->GetEntryPointFromJni()));
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetS(fn(soa.Env(), klass.get(), args[0], args[1]));
    } else if (shorty == "VIZ") {
      typedef void (fntype)(JNIEnv*, jclass, jint, jboolean);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedThreadStateChange tsc(self, kNative);
      fn(soa.Env(), klass.get(), args[0], args[1]);
    } else if (shorty == "ZLL") {
      typedef jboolean (fntype)(JNIEnv*, jclass, jobject, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg0(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[0])));
      ScopedLocalRef<jobject> arg1(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[1])));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetZ(fn(soa.Env(), klass.get(), arg0.get(), arg1.get()));
    } else if (shorty == "ZILL") {
      typedef jboolean (fntype)(JNIEnv*, jclass, jint, jobject, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg1(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[1])));
      ScopedLocalRef<jobject> arg2(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[2])));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetZ(fn(soa.Env(), klass.get(), args[0], arg1.get(), arg2.get()));
    } else if (shorty == "VILII") {
      typedef void (fntype)(JNIEnv*, jclass, jint, jobject, jint, jint);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg1(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[1])));
      ScopedThreadStateChange tsc(self, kNative);
      fn(soa.Env(), klass.get(), args[0], arg1.get(), args[2], args[3]);
    } else if (shorty == "VLILII") {
      typedef void (fntype)(JNIEnv*, jclass, jobject, jint, jobject, jint, jint);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jclass> klass(soa.Env(),
                                   soa.AddLocalReference<jclass>(method->GetDeclaringClass()));
      ScopedLocalRef<jobject> arg0(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[0])));
      ScopedLocalRef<jobject> arg2(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[2])));
      ScopedThreadStateChange tsc(self, kNative);
      fn(soa.Env(), klass.get(), arg0.get(), args[1], arg2.get(), args[3], args[4]);
    } else {
      LOG(FATAL) << "Do something with static native method: " << PrettyMethod(method)
          << " shorty: " << shorty;
    }
  } else {
    if (shorty == "L") {
      typedef jobject (fntype)(JNIEnv*, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jobject> rcvr(soa.Env(),
                                   soa.AddLocalReference<jobject>(receiver));
      jobject jresult;
      {
        ScopedThreadStateChange tsc(self, kNative);
        jresult = fn(soa.Env(), rcvr.get());
      }
      result->SetL(soa.Decode<Object*>(jresult));
    } else if (shorty == "V") {
      typedef void (fntype)(JNIEnv*, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jobject> rcvr(soa.Env(),
                                   soa.AddLocalReference<jobject>(receiver));
      ScopedThreadStateChange tsc(self, kNative);
      fn(soa.Env(), rcvr.get());
    } else if (shorty == "LL") {
      typedef jobject (fntype)(JNIEnv*, jobject, jobject);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jobject> rcvr(soa.Env(),
                                   soa.AddLocalReference<jobject>(receiver));
      ScopedLocalRef<jobject> arg0(soa.Env(),
                                   soa.AddLocalReference<jobject>(
                                       reinterpret_cast<Object*>(args[0])));
      jobject jresult;
      {
        ScopedThreadStateChange tsc(self, kNative);
        jresult = fn(soa.Env(), rcvr.get(), arg0.get());
      }
      result->SetL(soa.Decode<Object*>(jresult));
      ScopedThreadStateChange tsc(self, kNative);
    } else if (shorty == "III") {
      typedef jint (fntype)(JNIEnv*, jobject, jint, jint);
      fntype* const fn = reinterpret_cast<fntype*>(method->GetEntryPointFromJni());
      ScopedLocalRef<jobject> rcvr(soa.Env(),
                                   soa.AddLocalReference<jobject>(receiver));
      ScopedThreadStateChange tsc(self, kNative);
      result->SetI(fn(soa.Env(), rcvr.get(), args[0], args[1]));
    } else {
      LOG(FATAL) << "Do something with native method: " << PrettyMethod(method)
          << " shorty: " << shorty;
    }
  }
}

enum InterpreterImplKind {
  kSwitchImplKind,        // Switch-based interpreter implementation.
  kComputedGotoImplKind,  // Computed-goto-based interpreter implementation.
  kMterpImplKind          // Assembly interpreter
};
static std::ostream& operator<<(std::ostream& os, const InterpreterImplKind& rhs) {
  os << ((rhs == kSwitchImplKind)
              ? "Switch-based interpreter"
              : (rhs == kComputedGotoImplKind)
                  ? "Computed-goto-based interpreter"
                  : "Asm interpreter");
  return os;
}

static constexpr InterpreterImplKind kInterpreterImplKind = kMterpImplKind;

#if defined(__clang__)
// Clang 3.4 fails to build the goto interpreter implementation.
template<bool do_access_check, bool transaction_active>
JValue ExecuteGotoImpl(Thread*, const DexFile::CodeItem*, ShadowFrame&, JValue) {
  LOG(FATAL) << "UNREACHABLE";
  UNREACHABLE();
}
// Explicit definitions of ExecuteGotoImpl.
template<> SHARED_REQUIRES(Locks::mutator_lock_)
JValue ExecuteGotoImpl<true, false>(Thread* self, const DexFile::CodeItem* code_item,
                                    ShadowFrame& shadow_frame, JValue result_register);
template<> SHARED_REQUIRES(Locks::mutator_lock_)
JValue ExecuteGotoImpl<false, false>(Thread* self, const DexFile::CodeItem* code_item,
                                     ShadowFrame& shadow_frame, JValue result_register);
template<> SHARED_REQUIRES(Locks::mutator_lock_)
JValue ExecuteGotoImpl<true, true>(Thread* self,  const DexFile::CodeItem* code_item,
                                   ShadowFrame& shadow_frame, JValue result_register);
template<> SHARED_REQUIRES(Locks::mutator_lock_)
JValue ExecuteGotoImpl<false, true>(Thread* self, const DexFile::CodeItem* code_item,
                                    ShadowFrame& shadow_frame, JValue result_register);
#endif

static inline JValue Execute(
    Thread* self,
    const DexFile::CodeItem* code_item,
    ShadowFrame& shadow_frame,
    JValue result_register,
    bool stay_in_interpreter = false) SHARED_REQUIRES(Locks::mutator_lock_) {
  DCHECK(!shadow_frame.GetMethod()->IsAbstract());
  DCHECK(!shadow_frame.GetMethod()->IsNative());
  if (LIKELY(shadow_frame.GetDexPC() == 0)) {  // Entering the method, but not via deoptimization.
    if (kIsDebugBuild) {
      self->AssertNoPendingException();
    }
    instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
    ArtMethod *method = shadow_frame.GetMethod();

    if (UNLIKELY(instrumentation->HasMethodEntryListeners())) {
      instrumentation->MethodEnterEvent(self, shadow_frame.GetThisObject(code_item->ins_size_),
                                        method, 0);
    }

    if (!stay_in_interpreter) {
      jit::Jit* jit = Runtime::Current()->GetJit();
      if (jit != nullptr) {
        jit->MethodEntered(self, shadow_frame.GetMethod());
        if (jit->CanInvokeCompiledCode(method)) {
          JValue result;

          // Pop the shadow frame before calling into compiled code.
          self->PopShadowFrame();
          ArtInterpreterToCompiledCodeBridge(self, nullptr, code_item, &shadow_frame, &result);
          // Push the shadow frame back as the caller will expect it.
          self->PushShadowFrame(&shadow_frame);

          return result;
        }
      }
    }
  }

  shadow_frame.GetMethod()->GetDeclaringClass()->AssertInitializedOrInitializingInThread(self);

  // Lock counting is a special version of accessibility checks, and for simplicity and
  // reduction of template parameters, we gate it behind access-checks mode.
  ArtMethod* method = shadow_frame.GetMethod();
  DCHECK(!method->SkipAccessChecks() || !method->MustCountLocks());

  bool transaction_active = Runtime::Current()->IsActiveTransaction();
  if (LIKELY(method->SkipAccessChecks())) {
    // Enter the "without access check" interpreter.
    if (kInterpreterImplKind == kMterpImplKind) {
      if (transaction_active) {
        // No Mterp variant - just use the switch interpreter.
        return ExecuteSwitchImpl<false, true>(self, code_item, shadow_frame, result_register,
                                              false);
      } else if (UNLIKELY(!Runtime::Current()->IsStarted())) {
        return ExecuteSwitchImpl<false, false>(self, code_item, shadow_frame, result_register,
                                               false);
      } else {
        while (true) {
          // Mterp does not support all instrumentation/debugging.
          if (MterpShouldSwitchInterpreters() != 0) {
            return ExecuteSwitchImpl<false, false>(self, code_item, shadow_frame, result_register,
                                                   false);
          }
          bool returned = ExecuteMterpImpl(self, code_item, &shadow_frame, &result_register);
          if (returned) {
            return result_register;
          } else {
            // Mterp didn't like that instruction.  Single-step it with the reference interpreter.
            result_register = ExecuteSwitchImpl<false, false>(self, code_item, shadow_frame,
                                                               result_register, true);
            if (shadow_frame.GetDexPC() == DexFile::kDexNoIndex) {
              // Single-stepped a return or an exception not handled locally.  Return to caller.
              return result_register;
            }
          }
        }
      }
    } else if (kInterpreterImplKind == kSwitchImplKind) {
      if (transaction_active) {
        return ExecuteSwitchImpl<false, true>(self, code_item, shadow_frame, result_register,
                                              false);
      } else {
        return ExecuteSwitchImpl<false, false>(self, code_item, shadow_frame, result_register,
                                               false);
      }
    } else {
      DCHECK_EQ(kInterpreterImplKind, kComputedGotoImplKind);
      if (transaction_active) {
        return ExecuteGotoImpl<false, true>(self, code_item, shadow_frame, result_register);
      } else {
        return ExecuteGotoImpl<false, false>(self, code_item, shadow_frame, result_register);
      }
    }
  } else {
    // Enter the "with access check" interpreter.
    if (kInterpreterImplKind == kMterpImplKind) {
      // No access check variants for Mterp.  Just use the switch version.
      if (transaction_active) {
        return ExecuteSwitchImpl<true, true>(self, code_item, shadow_frame, result_register,
                                             false);
      } else {
        return ExecuteSwitchImpl<true, false>(self, code_item, shadow_frame, result_register,
                                              false);
      }
    } else if (kInterpreterImplKind == kSwitchImplKind) {
      if (transaction_active) {
        return ExecuteSwitchImpl<true, true>(self, code_item, shadow_frame, result_register,
                                             false);
      } else {
        return ExecuteSwitchImpl<true, false>(self, code_item, shadow_frame, result_register,
                                              false);
      }
    } else {
      DCHECK_EQ(kInterpreterImplKind, kComputedGotoImplKind);
      if (transaction_active) {
        return ExecuteGotoImpl<true, true>(self, code_item, shadow_frame, result_register);
      } else {
        return ExecuteGotoImpl<true, false>(self, code_item, shadow_frame, result_register);
      }
    }
  }
}

void EnterInterpreterFromInvoke(Thread* self, ArtMethod* method, Object* receiver,
                                uint32_t* args, JValue* result,
                                bool stay_in_interpreter) {
  DCHECK_EQ(self, Thread::Current());
  bool implicit_check = !Runtime::Current()->ExplicitStackOverflowChecks();
  if (UNLIKELY(__builtin_frame_address(0) < self->GetStackEndForInterpreter(implicit_check))) {
    ThrowStackOverflowError(self);
    return;
  }

  const char* old_cause = self->StartAssertNoThreadSuspension("EnterInterpreterFromInvoke");
  const DexFile::CodeItem* code_item = method->GetCodeItem();
  uint16_t num_regs;
  uint16_t num_ins;
  if (code_item != nullptr) {
    num_regs =  code_item->registers_size_;
    num_ins = code_item->ins_size_;
  } else if (!method->IsInvokable()) {
    self->EndAssertNoThreadSuspension(old_cause);
    method->ThrowInvocationTimeError();
    return;
  } else {
    DCHECK(method->IsNative());
    num_regs = num_ins = ArtMethod::NumArgRegisters(method->GetShorty());
    if (!method->IsStatic()) {
      num_regs++;
      num_ins++;
    }
  }
  // Set up shadow frame with matching number of reference slots to vregs.
  ShadowFrame* last_shadow_frame = self->GetManagedStack()->GetTopShadowFrame();
  ShadowFrameAllocaUniquePtr shadow_frame_unique_ptr =
      CREATE_SHADOW_FRAME(num_regs, last_shadow_frame, method, /* dex pc */ 0);
  ShadowFrame* shadow_frame = shadow_frame_unique_ptr.get();
  self->PushShadowFrame(shadow_frame);

  size_t cur_reg = num_regs - num_ins;
  if (!method->IsStatic()) {
    CHECK(receiver != nullptr);
    shadow_frame->SetVRegReference(cur_reg, receiver);
    ++cur_reg;
  }
  uint32_t shorty_len = 0;
  const char* shorty = method->GetShorty(&shorty_len);
  for (size_t shorty_pos = 0, arg_pos = 0; cur_reg < num_regs; ++shorty_pos, ++arg_pos, cur_reg++) {
    DCHECK_LT(shorty_pos + 1, shorty_len);
    switch (shorty[shorty_pos + 1]) {
      case 'L': {
        Object* o = reinterpret_cast<StackReference<Object>*>(&args[arg_pos])->AsMirrorPtr();
        shadow_frame->SetVRegReference(cur_reg, o);
        break;
      }
      case 'J': case 'D': {
        uint64_t wide_value = (static_cast<uint64_t>(args[arg_pos + 1]) << 32) | args[arg_pos];
        shadow_frame->SetVRegLong(cur_reg, wide_value);
        cur_reg++;
        arg_pos++;
        break;
      }
      default:
        shadow_frame->SetVReg(cur_reg, args[arg_pos]);
        break;
    }
  }
  self->EndAssertNoThreadSuspension(old_cause);
  // Do this after populating the shadow frame in case EnsureInitialized causes a GC.
  if (method->IsStatic() && UNLIKELY(!method->GetDeclaringClass()->IsInitialized())) {
    ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
    StackHandleScope<1> hs(self);
    Handle<mirror::Class> h_class(hs.NewHandle(method->GetDeclaringClass()));
    if (UNLIKELY(!class_linker->EnsureInitialized(self, h_class, true, true))) {
      CHECK(self->IsExceptionPending());
      self->PopShadowFrame();
      return;
    }
  }
  if (LIKELY(!method->IsNative())) {
    JValue r = Execute(self, code_item, *shadow_frame, JValue(), stay_in_interpreter);
    if (result != nullptr) {
      *result = r;
    }
  } else {
    // We don't expect to be asked to interpret native code (which is entered via a JNI compiler
    // generated stub) except during testing and image writing.
    // Update args to be the args in the shadow frame since the input ones could hold stale
    // references pointers due to moving GC.
    args = shadow_frame->GetVRegArgs(method->IsStatic() ? 0 : 1);
    if (!Runtime::Current()->IsStarted()) {
      UnstartedRuntime::Jni(self, method, receiver, args, result);
    } else {
      InterpreterJni(self, method, shorty, receiver, args, result);
    }
  }
  self->PopShadowFrame();
}

static bool IsStringInit(const Instruction* instr, ArtMethod* caller)
    SHARED_REQUIRES(Locks::mutator_lock_) {
  if (instr->Opcode() == Instruction::INVOKE_DIRECT ||
      instr->Opcode() == Instruction::INVOKE_DIRECT_RANGE) {
    // Instead of calling ResolveMethod() which has suspend point and can trigger
    // GC, look up the callee method symbolically.
    uint16_t callee_method_idx = (instr->Opcode() == Instruction::INVOKE_DIRECT_RANGE) ?
        instr->VRegB_3rc() : instr->VRegB_35c();
    const DexFile* dex_file = caller->GetDexFile();
    const DexFile::MethodId& method_id = dex_file->GetMethodId(callee_method_idx);
    const char* class_name = dex_file->StringByTypeIdx(method_id.class_idx_);
    const char* method_name = dex_file->GetMethodName(method_id);
    // Compare method's class name and method name against string init.
    // It's ok since it's not allowed to create your own java/lang/String.
    // TODO: verify that assumption.
    if ((strcmp(class_name, "Ljava/lang/String;") == 0) &&
        (strcmp(method_name, "<init>") == 0)) {
      return true;
    }
  }
  return false;
}

static int16_t GetReceiverRegisterForStringInit(const Instruction* instr) {
  DCHECK(instr->Opcode() == Instruction::INVOKE_DIRECT_RANGE ||
         instr->Opcode() == Instruction::INVOKE_DIRECT);
  return (instr->Opcode() == Instruction::INVOKE_DIRECT_RANGE) ?
      instr->VRegC_3rc() : instr->VRegC_35c();
}

void EnterInterpreterFromDeoptimize(Thread* self,
                                    ShadowFrame* shadow_frame,
                                    bool from_code,
                                    JValue* ret_val)
    SHARED_REQUIRES(Locks::mutator_lock_) {
  JValue value;
  // Set value to last known result in case the shadow frame chain is empty.
  value.SetJ(ret_val->GetJ());
  // Are we executing the first shadow frame?
  bool first = true;
  while (shadow_frame != nullptr) {
    // We do not want to recover lock state for lock counting when deoptimizing. Currently,
    // the compiler should not have compiled a method that failed structured-locking checks.
    DCHECK(!shadow_frame->GetMethod()->MustCountLocks());

    self->SetTopOfShadowStack(shadow_frame);
    const DexFile::CodeItem* code_item = shadow_frame->GetMethod()->GetCodeItem();
    const uint32_t dex_pc = shadow_frame->GetDexPC();
    uint32_t new_dex_pc = dex_pc;
    if (UNLIKELY(self->IsExceptionPending())) {
      // If we deoptimize from the QuickExceptionHandler, we already reported the exception to
      // the instrumentation. To prevent from reporting it a second time, we simply pass a
      // null Instrumentation*.
      const instrumentation::Instrumentation* const instrumentation =
          first ? nullptr : Runtime::Current()->GetInstrumentation();
      uint32_t found_dex_pc = FindNextInstructionFollowingException(self, *shadow_frame, dex_pc,
                                                                    instrumentation);
      new_dex_pc = found_dex_pc;  // the dex pc of a matching catch handler
                                  // or DexFile::kDexNoIndex if there is none.
    } else if (!from_code) {
      // For the debugger and full deoptimization stack, we must go past the invoke
      // instruction, as it already executed.
      // TODO: should be tested more once b/17586779 is fixed.
      const Instruction* instr = Instruction::At(&code_item->insns_[dex_pc]);
      if (instr->IsInvoke()) {
        if (IsStringInit(instr, shadow_frame->GetMethod())) {
          uint16_t this_obj_vreg = GetReceiverRegisterForStringInit(instr);
          // Move the StringFactory.newStringFromChars() result into the register representing
          // "this object" when invoking the string constructor in the original dex instruction.
          // Also move the result into all aliases.
          DCHECK(value.GetL()->IsString());
          SetStringInitValueToAllAliases(shadow_frame, this_obj_vreg, value);
          // Calling string constructor in the original dex code doesn't generate a result value.
          value.SetJ(0);
        }
        new_dex_pc = dex_pc + instr->SizeInCodeUnits();
      } else if (instr->Opcode() == Instruction::NEW_INSTANCE) {
        // It's possible to deoptimize at a NEW_INSTANCE dex instruciton that's for a
        // java string, which is turned into a call into StringFactory.newEmptyString();
        // Move the StringFactory.newEmptyString() result into the destination register.
        DCHECK(value.GetL()->IsString());
        shadow_frame->SetVRegReference(instr->VRegA_21c(), value.GetL());
        // new-instance doesn't generate a result value.
        value.SetJ(0);
        // Skip the dex instruction since we essentially come back from an invocation.
        new_dex_pc = dex_pc + instr->SizeInCodeUnits();
        if (kIsDebugBuild) {
          ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
          // This is a suspend point. But it's ok since value has been set into shadow_frame.
          mirror::Class* klass = class_linker->ResolveType(
              instr->VRegB_21c(), shadow_frame->GetMethod());
          DCHECK(klass->IsStringClass());
        }
      } else {
        CHECK(false) << "Unexpected instruction opcode " << instr->Opcode()
                     << " at dex_pc " << dex_pc
                     << " of method: " << PrettyMethod(shadow_frame->GetMethod(), false);
      }
    } else {
      // Nothing to do, the dex_pc is the one at which the code requested
      // the deoptimization.
    }
    if (new_dex_pc != DexFile::kDexNoIndex) {
      shadow_frame->SetDexPC(new_dex_pc);
      value = Execute(self, code_item, *shadow_frame, value);
    }
    ShadowFrame* old_frame = shadow_frame;
    shadow_frame = shadow_frame->GetLink();
    ShadowFrame::DeleteDeoptimizedFrame(old_frame);
    // Following deoptimizations of shadow frames must pass the invoke instruction.
    from_code = false;
    first = false;
  }
  ret_val->SetJ(value.GetJ());
}

JValue EnterInterpreterFromEntryPoint(Thread* self, const DexFile::CodeItem* code_item,
                                      ShadowFrame* shadow_frame) {
  DCHECK_EQ(self, Thread::Current());
  bool implicit_check = !Runtime::Current()->ExplicitStackOverflowChecks();
  if (UNLIKELY(__builtin_frame_address(0) < self->GetStackEndForInterpreter(implicit_check))) {
    ThrowStackOverflowError(self);
    return JValue();
  }

  jit::Jit* jit = Runtime::Current()->GetJit();
  if (jit != nullptr) {
    jit->NotifyCompiledCodeToInterpreterTransition(self, shadow_frame->GetMethod());
  }
  return Execute(self, code_item, *shadow_frame, JValue());
}

void ArtInterpreterToInterpreterBridge(Thread* self, const DexFile::CodeItem* code_item,
                                       ShadowFrame* shadow_frame, JValue* result) {
  bool implicit_check = !Runtime::Current()->ExplicitStackOverflowChecks();
  if (UNLIKELY(__builtin_frame_address(0) < self->GetStackEndForInterpreter(implicit_check))) {
    ThrowStackOverflowError(self);
    return;
  }

  self->PushShadowFrame(shadow_frame);
  ArtMethod* method = shadow_frame->GetMethod();
  // Ensure static methods are initialized.
  const bool is_static = method->IsStatic();
  if (is_static) {
    mirror::Class* declaring_class = method->GetDeclaringClass();
    if (UNLIKELY(!declaring_class->IsInitialized())) {
      StackHandleScope<1> hs(self);
      HandleWrapper<Class> h_declaring_class(hs.NewHandleWrapper(&declaring_class));
      if (UNLIKELY(!Runtime::Current()->GetClassLinker()->EnsureInitialized(
          self, h_declaring_class, true, true))) {
        DCHECK(self->IsExceptionPending());
        self->PopShadowFrame();
        return;
      }
      CHECK(h_declaring_class->IsInitializing());
    }
  }

  if (LIKELY(!shadow_frame->GetMethod()->IsNative())) {
    result->SetJ(Execute(self, code_item, *shadow_frame, JValue()).GetJ());
  } else {
    // We don't expect to be asked to interpret native code (which is entered via a JNI compiler
    // generated stub) except during testing and image writing.
    CHECK(!Runtime::Current()->IsStarted());
    Object* receiver = is_static ? nullptr : shadow_frame->GetVRegReference(0);
    uint32_t* args = shadow_frame->GetVRegArgs(is_static ? 0 : 1);
    UnstartedRuntime::Jni(self, shadow_frame->GetMethod(), receiver, args, result);
  }

  self->PopShadowFrame();
}

void CheckInterpreterAsmConstants() {
  CheckMterpAsmConstants();
}

void InitInterpreterTls(Thread* self) {
  InitMterpTls(self);
}

}  // namespace interpreter
}  // namespace art