// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include <setjmp.h>  // NOLINT
#include <stdlib.h>

#include "vm/globals.h"
#if defined(TARGET_ARCH_DBC)

#if !defined(USING_SIMULATOR)
#error "DBC is a simulated architecture"
#endif

#include "vm/simulator.h"

#include "vm/assembler.h"
#include "vm/compiler.h"
#include "vm/constants_dbc.h"
#include "vm/cpu.h"
#include "vm/dart_entry.h"
#include "vm/debugger.h"
#include "vm/disassembler.h"
#include "vm/lockers.h"
#include "vm/native_arguments.h"
#include "vm/native_entry.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/os_thread.h"
#include "vm/stack_frame.h"

namespace dart {

DEFINE_FLAG(uint64_t, trace_sim_after, ULLONG_MAX,
            "Trace simulator execution after instruction count reached.");
DEFINE_FLAG(uint64_t, stop_sim_at, ULLONG_MAX,
            "Instruction address or instruction count to stop simulator at.");

// SimulatorSetjmpBuffer are linked together, and the last created one
// is referenced by the Simulator. When an exception is thrown, the exception
// runtime looks at where to jump and finds the corresponding
// SimulatorSetjmpBuffer based on the stack pointer of the exception handler.
// The runtime then does a Longjmp on that buffer to return to the simulator.
class SimulatorSetjmpBuffer {
 public:
  void Longjmp() {
    // "This" is now the last setjmp buffer.
    simulator_->set_last_setjmp_buffer(this);
    longjmp(buffer_, 1);
  }

  explicit SimulatorSetjmpBuffer(Simulator* sim) {
    simulator_ = sim;
    link_ = sim->last_setjmp_buffer();
    sim->set_last_setjmp_buffer(this);
    sp_ = sim->sp_;
    fp_ = sim->fp_;
  }

  ~SimulatorSetjmpBuffer() {
    ASSERT(simulator_->last_setjmp_buffer() == this);
    simulator_->set_last_setjmp_buffer(link_);
  }

  SimulatorSetjmpBuffer* link() const { return link_; }

  uword sp() const { return reinterpret_cast<uword>(sp_); }
  uword fp() const { return reinterpret_cast<uword>(fp_); }

  jmp_buf buffer_;

 private:
  RawObject** sp_;
  RawObject** fp_;
  Simulator* simulator_;
  SimulatorSetjmpBuffer* link_;

  friend class Simulator;

  DISALLOW_ALLOCATION();
  DISALLOW_COPY_AND_ASSIGN(SimulatorSetjmpBuffer);
};


DART_FORCE_INLINE static RawObject** SavedCallerFP(RawObject** FP) {
  return reinterpret_cast<RawObject**>(FP[kSavedCallerFpSlotFromFp]);
}


DART_FORCE_INLINE static RawObject** FrameArguments(RawObject** FP,
                                                    intptr_t argc) {
  return FP - (kDartFrameFixedSize + argc);
}


#define RAW_CAST(Type, val)  (SimulatorHelpers::CastTo##Type(val))


class SimulatorHelpers {
 public:
#define DEFINE_CASTS(Type)                                              \
    DART_FORCE_INLINE static Raw##Type* CastTo##Type(RawObject* obj) {  \
      ASSERT((k##Type##Cid == kSmiCid) ? !obj->IsHeapObject()           \
                                       : obj->Is##Type());              \
      return reinterpret_cast<Raw##Type*>(obj);                         \
    }
  CLASS_LIST(DEFINE_CASTS)
#undef DEFINE_CASTS

  DART_FORCE_INLINE static RawSmi* GetClassIdAsSmi(RawObject* obj) {
    return Smi::New(obj->IsHeapObject() ? obj->GetClassId()
                                        : static_cast<intptr_t>(kSmiCid));
  }

  DART_FORCE_INLINE static intptr_t GetClassId(RawObject* obj) {
    return obj->IsHeapObject() ? obj->GetClassId()
                               : static_cast<intptr_t>(kSmiCid);
  }

  DART_FORCE_INLINE static void IncrementUsageCounter(RawFunction* f) {
    f->ptr()->usage_counter_++;
  }

  DART_FORCE_INLINE static bool IsStrictEqualWithNumberCheck(RawObject* lhs,
                                                             RawObject* rhs) {
    if (lhs == rhs) {
      return true;
    }

    if (lhs->IsHeapObject() && rhs->IsHeapObject()) {
      const intptr_t lhs_cid = lhs->GetClassId();
      const intptr_t rhs_cid = rhs->GetClassId();
      if (lhs_cid == rhs_cid) {
        switch (lhs_cid) {
          case kDoubleCid:
            return (bit_cast<uint64_t, double>(
                        static_cast<RawDouble*>(lhs)->ptr()->value_) ==
                    bit_cast<uint64_t, double>(
                        static_cast<RawDouble*>(rhs)->ptr()->value_));

          case kMintCid:
            return (static_cast<RawMint*>(lhs)->ptr()->value_ ==
                    static_cast<RawMint*>(rhs)->ptr()->value_);

          case kBigintCid:
            return (DLRT_BigintCompare(static_cast<RawBigint*>(lhs),
                                       static_cast<RawBigint*>(rhs)) == 0);
        }
      }
    }

    return false;
  }

  template <typename T>
  DART_FORCE_INLINE static T* Untag(T* tagged) {
    return tagged->ptr();
  }

  DART_FORCE_INLINE static bool CheckIndex(RawSmi* index, RawSmi* length) {
    return !index->IsHeapObject() &&
           (reinterpret_cast<intptr_t>(index) >= 0) &&
           (reinterpret_cast<intptr_t>(index) <
                reinterpret_cast<intptr_t>(length));
  }

  static bool ObjectArraySetIndexed(Thread* thread,
                                    RawObject** FP,
                                    RawObject** result) {
    if (thread->isolate()->type_checks()) {
      return false;
    }

    RawObject** args = FrameArguments(FP, 3);
    RawSmi* index = static_cast<RawSmi*>(args[1]);
    RawArray* array = static_cast<RawArray*>(args[0]);
    if (CheckIndex(index, array->ptr()->length_)) {
      array->StorePointer(array->ptr()->data() + Smi::Value(index), args[2]);
      return true;
    }
    return false;
  }

  static bool ObjectArrayGetIndexed(Thread* thread,
                                    RawObject** FP,
                                    RawObject** result) {
    RawObject** args = FrameArguments(FP, 2);
    RawSmi* index = static_cast<RawSmi*>(args[1]);
    RawArray* array = static_cast<RawArray*>(args[0]);
    if (CheckIndex(index, array->ptr()->length_)) {
      *result = array->ptr()->data()[Smi::Value(index)];
      return true;
    }
    return false;
  }

  static bool GrowableArraySetIndexed(Thread* thread,
                                      RawObject** FP,
                                      RawObject** result) {
    if (thread->isolate()->type_checks()) {
      return false;
    }

    RawObject** args = FrameArguments(FP, 3);
    RawSmi* index = static_cast<RawSmi*>(args[1]);
    RawGrowableObjectArray* array =
        static_cast<RawGrowableObjectArray*>(args[0]);
    if (CheckIndex(index, array->ptr()->length_)) {
      RawArray* data = array->ptr()->data_;
      data->StorePointer(data->ptr()->data() + Smi::Value(index), args[2]);
      return true;
    }
    return false;
  }

  static bool GrowableArrayGetIndexed(Thread* thread,
                                      RawObject** FP,
                                      RawObject** result) {
    RawObject** args = FrameArguments(FP, 2);
    RawSmi* index = static_cast<RawSmi*>(args[1]);
    RawGrowableObjectArray* array =
        static_cast<RawGrowableObjectArray*>(args[0]);
    if (CheckIndex(index, array->ptr()->length_)) {
      *result = array->ptr()->data_->ptr()->data()[Smi::Value(index)];
      return true;
    }
    return false;
  }

  DART_FORCE_INLINE static RawCode* FrameCode(RawObject** FP) {
    ASSERT(GetClassId(FP[kPcMarkerSlotFromFp]) == kCodeCid);
    return static_cast<RawCode*>(FP[kPcMarkerSlotFromFp]);
  }


  DART_FORCE_INLINE static void SetFrameCode(RawObject** FP, RawCode* code) {
    ASSERT(GetClassId(code) == kCodeCid);
    FP[kPcMarkerSlotFromFp] = code;
  }
};


DART_FORCE_INLINE static uint32_t* SavedCallerPC(RawObject** FP) {
  return reinterpret_cast<uint32_t*>(FP[kSavedCallerPcSlotFromFp]);
}


DART_FORCE_INLINE static RawFunction* FrameFunction(RawObject** FP) {
  RawFunction* function = static_cast<RawFunction*>(FP[kFunctionSlotFromFp]);
  ASSERT(SimulatorHelpers::GetClassId(function) == kFunctionCid);
  return function;
}


IntrinsicHandler Simulator::intrinsics_[Simulator::kIntrinsicCount];


// Synchronization primitives support.
void Simulator::InitOnce() {
  for (intptr_t i = 0; i < kIntrinsicCount; i++) {
    intrinsics_[i] = 0;
  }

  intrinsics_[kObjectArraySetIndexedIntrinsic] =
      SimulatorHelpers::ObjectArraySetIndexed;
  intrinsics_[kObjectArrayGetIndexedIntrinsic] =
      SimulatorHelpers::ObjectArrayGetIndexed;
  intrinsics_[kGrowableArraySetIndexedIntrinsic] =
      SimulatorHelpers::GrowableArraySetIndexed;
  intrinsics_[kGrowableArrayGetIndexedIntrinsic] =
      SimulatorHelpers::GrowableArrayGetIndexed;
}


Simulator::Simulator()
    : stack_(NULL),
      fp_(NULL),
      sp_(NULL) {
  // Setup simulator support first. Some of this information is needed to
  // setup the architecture state.
  // We allocate the stack here, the size is computed as the sum of
  // the size specified by the user and the buffer space needed for
  // handling stack overflow exceptions. To be safe in potential
  // stack underflows we also add some underflow buffer space.
  stack_ = new uintptr_t[(OSThread::GetSpecifiedStackSize() +
                          OSThread::kStackSizeBuffer +
                          kSimulatorStackUnderflowSize) /
                         sizeof(uintptr_t)];
  last_setjmp_buffer_ = NULL;
  top_exit_frame_info_ = 0;
}


Simulator::~Simulator() {
  delete[] stack_;
  Isolate* isolate = Isolate::Current();
  if (isolate != NULL) {
    isolate->set_simulator(NULL);
  }
}


// Get the active Simulator for the current isolate.
Simulator* Simulator::Current() {
  Simulator* simulator = Isolate::Current()->simulator();
  if (simulator == NULL) {
    simulator = new Simulator();
    Isolate::Current()->set_simulator(simulator);
  }
  return simulator;
}


// Returns the top of the stack area to enable checking for stack pointer
// validity.
uword Simulator::StackTop() const {
  // To be safe in potential stack underflows we leave some buffer above and
  // set the stack top.
  return StackBase() +
         (OSThread::GetSpecifiedStackSize() + OSThread::kStackSizeBuffer);
}


// Calls into the Dart runtime are based on this interface.
typedef void (*SimulatorRuntimeCall)(NativeArguments arguments);

// Calls to leaf Dart runtime functions are based on this interface.
typedef intptr_t (*SimulatorLeafRuntimeCall)(intptr_t r0,
                                             intptr_t r1,
                                             intptr_t r2,
                                             intptr_t r3);

// Calls to leaf float Dart runtime functions are based on this interface.
typedef double (*SimulatorLeafFloatRuntimeCall)(double d0, double d1);

// Calls to native Dart functions are based on this interface.
typedef void (*SimulatorBootstrapNativeCall)(NativeArguments* arguments);
typedef void (*SimulatorNativeCall)(NativeArguments* arguments, uword target);


void Simulator::Exit(Thread* thread,
                     RawObject** base,
                     RawObject** frame,
                     uint32_t* pc) {
  frame[0] = Function::null();
  frame[1] = Code::null();
  frame[2] = reinterpret_cast<RawObject*>(pc);
  frame[3] = reinterpret_cast<RawObject*>(base);
  fp_ = sp_ = frame + kDartFrameFixedSize;
  thread->set_top_exit_frame_info(reinterpret_cast<uword>(sp_));
}

// TODO(vegorov): Investigate advantages of using
// __builtin_s{add,sub,mul}_overflow() intrinsics here and below.
// Note that they may clobber the output location even when there is overflow:
// https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html
DART_FORCE_INLINE static bool SignedAddWithOverflow(intptr_t lhs,
                                                    intptr_t rhs,
                                                    intptr_t* out) {
  intptr_t res = 1;
#if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
  asm volatile(
      "add %2, %1\n"
      "jo 1f;\n"
      "xor %0, %0\n"
      "mov %1, 0(%3)\n"
      "1: "
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#elif defined(HOST_ARCH_ARM) || defined(HOST_ARCH_ARM64)
  asm volatile(
      "adds %1, %1, %2;\n"
      "bvs 1f;\n"
      "mov %0, #0;\n"
      "str %1, [%3, #0]\n"
      "1:"
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#else
#error "Unsupported platform"
#endif
  return (res != 0);
}


DART_FORCE_INLINE static bool SignedSubWithOverflow(intptr_t lhs,
                                                    intptr_t rhs,
                                                    intptr_t* out) {
  intptr_t res = 1;
#if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
  asm volatile(
      "sub %2, %1\n"
      "jo 1f;\n"
      "xor %0, %0\n"
      "mov %1, 0(%3)\n"
      "1: "
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#elif defined(HOST_ARCH_ARM) || defined(HOST_ARCH_ARM64)
  asm volatile(
      "subs %1, %1, %2;\n"
      "bvs 1f;\n"
      "mov %0, #0;\n"
      "str %1, [%3, #0]\n"
      "1:"
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#else
#error "Unsupported platform"
#endif
  return (res != 0);
}


DART_FORCE_INLINE static bool SignedMulWithOverflow(intptr_t lhs,
                                                    intptr_t rhs,
                                                    intptr_t* out) {
  intptr_t res = 1;
#if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
  asm volatile(
      "imul %2, %1\n"
      "jo 1f;\n"
      "xor %0, %0\n"
      "mov %1, 0(%3)\n"
      "1: "
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#elif defined(HOST_ARCH_ARM)
  asm volatile(
      "smull %1, ip, %1, %2;\n"
      "cmp ip, %1, ASR #31;\n"
      "bne 1f;\n"
      "mov %0, $0;\n"
      "str %1, [%3, #0]\n"
      "1:"
      : "+r"(res), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc", "r12");
#elif defined(HOST_ARCH_ARM64)
  int64_t prod_lo;
  asm volatile(
      "mul %1, %2, %3\n"
      "smulh %2, %2, %3\n"
      "cmp %2, %1, ASR #63;\n"
      "bne 1f;\n"
      "mov %0, #0;\n"
      "str %1, [%4, #0]\n"
      "1:"
      : "+r"(res), "=r"(prod_lo), "+r"(lhs)
      : "r"(rhs), "r"(out)
      : "cc");
#else
#error "Unsupported platform"
#endif
  return (res != 0);
}


#define LIKELY(cond) __builtin_expect((cond), 1)


DART_FORCE_INLINE static bool AreBothSmis(intptr_t a, intptr_t b) {
  return ((a | b) & kHeapObjectTag) == 0;
}


#define SMI_MUL(lhs, rhs, pres) SignedMulWithOverflow((lhs), (rhs) >> 1, pres)
#define SMI_COND(cond, lhs, rhs, pres) \
  ((*(pres) = ((lhs cond rhs) ? true_value : false_value)), false)
#define SMI_EQ(lhs, rhs, pres) SMI_COND(==, lhs, rhs, pres)
#define SMI_LT(lhs, rhs, pres) SMI_COND(<, lhs, rhs, pres)
#define SMI_GT(lhs, rhs, pres) SMI_COND(>, lhs, rhs, pres)
#define SMI_BITOR(lhs, rhs, pres) ((*(pres) = (lhs | rhs)), false)
#define SMI_BITAND(lhs, rhs, pres) ((*(pres) = ((lhs) & (rhs))), false)


void Simulator::CallRuntime(Thread* thread,
                            RawObject** base,
                            RawObject** exit_frame,
                            uint32_t* pc,
                            intptr_t argc_tag,
                            RawObject** args,
                            RawObject** result,
                            uword target) {
  Exit(thread, base, exit_frame, pc);
  NativeArguments native_args(thread, argc_tag, args, result);
  reinterpret_cast<RuntimeFunction>(target)(native_args);
}


DART_FORCE_INLINE static void EnterSyntheticFrame(RawObject*** FP,
                                                  RawObject*** SP,
                                                  uint32_t* pc) {
  RawObject** fp = *SP + kDartFrameFixedSize;
  fp[kPcMarkerSlotFromFp] = 0;
  fp[kSavedCallerPcSlotFromFp] = reinterpret_cast<RawObject*>(pc);
  fp[kSavedCallerFpSlotFromFp] = reinterpret_cast<RawObject*>(*FP);
  *FP = fp;
  *SP = fp - 1;
}


DART_FORCE_INLINE static void LeaveSyntheticFrame(RawObject*** FP,
                                                  RawObject*** SP) {
  RawObject** fp = *FP;
  *FP = reinterpret_cast<RawObject**>(fp[kSavedCallerFpSlotFromFp]);
  *SP = fp - kDartFrameFixedSize;
}


DART_FORCE_INLINE void Simulator::Invoke(Thread* thread,
                                         RawObject** call_base,
                                         RawObject** call_top,
                                         RawObjectPool** pp,
                                         uint32_t** pc,
                                         RawObject*** FP,
                                         RawObject*** SP) {
  RawObject** callee_fp = call_top + kDartFrameFixedSize;

  RawFunction* function = FrameFunction(callee_fp);
  RawCode* code = function->ptr()->code_;
  callee_fp[kPcMarkerSlotFromFp] = code;
  callee_fp[kSavedCallerPcSlotFromFp] = reinterpret_cast<RawObject*>(*pc);
  callee_fp[kSavedCallerFpSlotFromFp] = reinterpret_cast<RawObject*>(*FP);
  *pp = code->ptr()->object_pool_->ptr();
  *pc = reinterpret_cast<uint32_t*>(code->ptr()->entry_point_);
  *FP = callee_fp;
  *SP = *FP - 1;
}


void Simulator::InlineCacheMiss(int checked_args,
                                Thread* thread,
                                RawICData* icdata,
                                RawObject** args,
                                RawObject** top,
                                uint32_t* pc,
                                RawObject** FP,
                                RawObject** SP) {
  RawObject** result = top;
  RawObject** miss_handler_args = top + 1;
  for (intptr_t i = 0; i < checked_args; i++) {
    miss_handler_args[i] = args[i];
  }
  miss_handler_args[checked_args] = icdata;
  RuntimeFunction handler = NULL;
  switch (checked_args) {
    case 1:
      handler = DRT_InlineCacheMissHandlerOneArg;
      break;
    case 2:
      handler = DRT_InlineCacheMissHandlerTwoArgs;
      break;
    case 3:
      handler = DRT_InlineCacheMissHandlerThreeArgs;
      break;
    default:
      UNREACHABLE();
      break;
  }

  // Handler arguments: arguments to check and an ICData object.
  const intptr_t miss_handler_argc = checked_args + 1;
  RawObject** exit_frame = miss_handler_args + miss_handler_argc;
  CallRuntime(thread,
              FP,
              exit_frame,
              pc,
              miss_handler_argc,
              miss_handler_args,
              result,
              reinterpret_cast<uword>(handler));
}


DART_FORCE_INLINE void Simulator::InstanceCall1(Thread* thread,
                                                RawICData* icdata,
                                                RawObject** call_base,
                                                RawObject** top,
                                                RawArray** argdesc,
                                                RawObjectPool** pp,
                                                uint32_t** pc,
                                                RawObject*** FP,
                                                RawObject*** SP) {
  ASSERT(icdata->GetClassId() == kICDataCid);

  const intptr_t kCheckedArgs = 1;
  RawObject** args = call_base;
  RawArray* cache = icdata->ptr()->ic_data_->ptr();

  RawSmi* receiver_cid = SimulatorHelpers::GetClassIdAsSmi(args[0]);

  bool found = false;
  const intptr_t length = Smi::Value(cache->length_);
  for (intptr_t i = 0;
       i < (length - (kCheckedArgs + 2)); i += (kCheckedArgs + 2)) {
    if (cache->data()[i + 0] == receiver_cid) {
      top[0] = cache->data()[i + kCheckedArgs];
      found = true;
      break;
    }
  }

  if (!found) {
    InlineCacheMiss(
        kCheckedArgs, thread, icdata, call_base, top, *pc, *FP, *SP);
  }

  *argdesc = icdata->ptr()->args_descriptor_;
  Invoke(thread, call_base, top, pp, pc, FP, SP);
}


DART_FORCE_INLINE void Simulator::InstanceCall2(Thread* thread,
                                                RawICData* icdata,
                                                RawObject** call_base,
                                                RawObject** top,
                                                RawArray** argdesc,
                                                RawObjectPool** pp,
                                                uint32_t** pc,
                                                RawObject*** FP,
                                                RawObject*** SP) {
  ASSERT(icdata->GetClassId() == kICDataCid);

  const intptr_t kCheckedArgs = 2;
  RawObject** args = call_base;
  RawArray* cache = icdata->ptr()->ic_data_->ptr();

  RawSmi* receiver_cid = SimulatorHelpers::GetClassIdAsSmi(args[0]);
  RawSmi* arg0_cid = SimulatorHelpers::GetClassIdAsSmi(args[1]);

  bool found = false;
  const intptr_t length = Smi::Value(cache->length_);
  for (intptr_t i = 0;
       i < (length - (kCheckedArgs + 2)); i += (kCheckedArgs + 2)) {
    if ((cache->data()[i + 0] == receiver_cid) &&
        (cache->data()[i + 1] == arg0_cid)) {
      top[0] = cache->data()[i + kCheckedArgs];
      found = true;
      break;
    }
  }

  if (!found) {
    InlineCacheMiss(
        kCheckedArgs, thread, icdata, call_base, top, *pc, *FP, *SP);
  }

  *argdesc = icdata->ptr()->args_descriptor_;
  Invoke(thread, call_base, top, pp, pc, FP, SP);
}


// Note: functions below are marked DART_NOINLINE to recover performance on
// ARM where inlining these functions into the interpreter loop seemed to cause
// some code quality issues.
static DART_NOINLINE bool InvokeRuntime(
    Thread* thread,
    Simulator* sim,
    RuntimeFunction drt,
    const NativeArguments& args) {
  SimulatorSetjmpBuffer buffer(sim);
  if (!setjmp(buffer.buffer_)) {
    thread->set_vm_tag(reinterpret_cast<uword>(drt));
    drt(args);
    thread->set_vm_tag(VMTag::kDartTagId);
    return true;
  } else {
    return false;
  }
}


static DART_NOINLINE bool InvokeNative(
    Thread* thread,
    Simulator* sim,
    SimulatorBootstrapNativeCall f,
    NativeArguments* args) {
  SimulatorSetjmpBuffer buffer(sim);
  if (!setjmp(buffer.buffer_)) {
    thread->set_vm_tag(reinterpret_cast<uword>(f));
    f(args);
    thread->set_vm_tag(VMTag::kDartTagId);
    return true;
  } else {
    return false;
  }
}


static DART_NOINLINE bool InvokeNativeWrapper(
    Thread* thread,
    Simulator* sim,
    Dart_NativeFunction f,
    NativeArguments* args) {
  SimulatorSetjmpBuffer buffer(sim);
  if (!setjmp(buffer.buffer_)) {
    thread->set_vm_tag(reinterpret_cast<uword>(f));
    NativeEntry::NativeCallWrapper(reinterpret_cast<Dart_NativeArguments>(args),
                                   f);
    thread->set_vm_tag(VMTag::kDartTagId);
    return true;
  } else {
    return false;
  }
}

// Note: all macro helpers are intended to be used only inside Simulator::Call.

// Decode opcode and A part of the given value and dispatch to the
// corresponding bytecode handler.
#define DISPATCH_OP(val)         \
  do {                           \
    op = (val);                \
    rA = ((op >> 8) & 0xFF);   \
    goto* dispatch[op & 0xFF]; \
  } while (0)

// Fetch next operation from PC, increment program counter and dispatch.
#define DISPATCH() DISPATCH_OP(*pc++)

// Define entry point that handles bytecode Name with the given operand format.
#define BYTECODE(Name, Operands) \
  BYTECODE_HEADER(Name, DECLARE_##Operands, DECODE_##Operands)

#define BYTECODE_HEADER(Name, Declare, Decode) \
  Declare;                                     \
  bc##Name : Decode                            \

// Helpers to decode common instruction formats. Used in conjunction with
// BYTECODE() macro.
#define DECLARE_A_B_C uint16_t rB, rC; USE(rB); USE(rC)
#define DECODE_A_B_C \
  rB = ((op >> Bytecode::kBShift) & Bytecode::kBMask);    \
  rC = ((op >> Bytecode::kCShift) & Bytecode::kCMask);

#define DECLARE_0
#define DECODE_0

#define DECLARE_A
#define DECODE_A

#define DECLARE___D uint32_t rD; USE(rD)
#define DECODE___D rD = (op >> Bytecode::kDShift);

#define DECLARE_A_D DECLARE___D
#define DECODE_A_D DECODE___D

#define DECLARE_A_X int32_t rD; USE(rD)
#define DECODE_A_X rD = (static_cast<int32_t>(op) >> Bytecode::kDShift);

// Declare bytecode handler for a smi operation (e.g. AddTOS) with the
// given result type and the given behavior specified as a function
// that takes left and right operands and result slot and returns
// true if fast-path succeeds.
#define SMI_FASTPATH_TOS(ResultT, Func)                                        \
  {                                                                            \
    const intptr_t lhs = reinterpret_cast<intptr_t>(SP[-1]);                   \
    const intptr_t rhs = reinterpret_cast<intptr_t>(SP[-0]);                   \
    ResultT* slot = reinterpret_cast<ResultT*>(SP - 1);                        \
    if (LIKELY(AreBothSmis(lhs, rhs) && !Func(lhs, rhs, slot))) {              \
      /* Fast path succeeded. Skip the generic call that follows. */           \
      pc++;                                                                    \
      /* We dropped 2 arguments and push result                   */           \
      SP--;                                                                    \
    }                                                                          \
  }

// Exception handling helper. Gets handler FP and PC from the Simulator where
// they were stored by Simulator::Longjmp and proceeds to execute the handler.
// Corner case: handler PC can be a fake marker that marks entry frame, which
// means exception was not handled in the Dart code. In this case we return
// caught exception from Simulator::Call.
#define HANDLE_EXCEPTION                                                       \
  do {                                                                         \
    FP = reinterpret_cast<RawObject**>(fp_);                                   \
    pc = reinterpret_cast<uint32_t*>(pc_);                                     \
    if ((reinterpret_cast<uword>(pc) & 2) != 0) {  /* Entry frame? */          \
      fp_ = sp_ = reinterpret_cast<RawObject**>(fp_[0]);                       \
      thread->set_top_exit_frame_info(reinterpret_cast<uword>(sp_));           \
      thread->set_top_resource(top_resource);                                  \
      thread->set_vm_tag(vm_tag);                                              \
      return special_[kExceptionSpecialIndex];                                 \
    }                                                                          \
    pp = SimulatorHelpers::FrameCode(FP)->ptr()->object_pool_->ptr();          \
    goto DispatchAfterException;                                               \
  } while (0)                                                                  \

// Runtime call helpers: handle invocation and potential exception after return.
#define INVOKE_RUNTIME(Func, Args)                \
  if (!InvokeRuntime(thread, this, Func, Args)) { \
    HANDLE_EXCEPTION;                             \
  }                                               \

#define INVOKE_NATIVE(Func, Args)                 \
  if (!InvokeNative(thread, this, Func, &Args)) { \
    HANDLE_EXCEPTION;                             \
  }                                               \

#define INVOKE_NATIVE_WRAPPER(Func, Args)                \
  if (!InvokeNativeWrapper(thread, this, Func, &Args)) { \
    HANDLE_EXCEPTION;                                    \
  }                                                      \

#define LOAD_CONSTANT(index) (pp->data()[(index)].raw_obj_)

RawObject* Simulator::Call(const Code& code,
                           const Array& arguments_descriptor,
                           const Array& arguments,
                           Thread* thread) {
  // Dispatch used to interpret bytecode. Contains addresses of
  // labels of bytecode handlers. Handlers themselves are defined below.
  static const void* dispatch[] = {
#define TARGET(name, fmt, fmta, fmtb, fmtc) &&bc##name,
      BYTECODES_LIST(TARGET)
#undef TARGET
  };

  // Interpreter state (see constants_dbc.h for high-level overview).
  uint32_t* pc;  // Program Counter: points to the next op to execute.
  RawObjectPool* pp;  // Pool Pointer.
  RawObject** FP;  // Frame Pointer.
  RawObject** SP;  // Stack Pointer.

  RawArray* argdesc;  // Arguments Descriptor: used to pass information between
                      // call instruction and the function entry.

  uint32_t op;  // Currently executing op.
  uint16_t rA;  // A component of the currently executing op.

  if (sp_ == NULL) {
    fp_ = sp_ = reinterpret_cast<RawObject**>(stack_);
  }

  // Save current VM tag and mark thread as executing Dart code.
  const uword vm_tag = thread->vm_tag();
  thread->set_vm_tag(VMTag::kDartTagId);

  // Save current top stack resource and reset the list.
  StackResource* top_resource = thread->top_resource();
  thread->set_top_resource(NULL);

  // Setup entry frame:
  //
  //                        ^
  //                        |  previous Dart frames
  //       ~~~~~~~~~~~~~~~  |
  //       | ........... | -+
  // fp_ > |             |     saved top_exit_frame_info
  //       | arg 0       | -+
  //       ~~~~~~~~~~~~~~~  |
  //                         > incoming arguments
  //       ~~~~~~~~~~~~~~~  |
  //       | arg 1       | -+
  //       | function    | -+
  //       | code        |  |
  //       | callee PC   | ---> special fake PC marking an entry frame
  //  SP > | fp_         |  |
  //  FP > | ........... |   > normal Dart frame (see stack_frame_dbc.h)
  //                        |
  //                        v
  //
  FP = fp_ + 1 + arguments.Length() + kDartFrameFixedSize;
  SP = FP - 1;

  // Save outer top_exit_frame_info.
  fp_[0] = reinterpret_cast<RawObject*>(thread->top_exit_frame_info());

  // Copy arguments and setup the Dart frame.
  const intptr_t argc = arguments.Length();
  for (intptr_t i = 0; i < argc; i++) {
    fp_[1 + i] = arguments.At(i);
  }

  FP[kFunctionSlotFromFp] = code.function();
  FP[kPcMarkerSlotFromFp] = code.raw();
  FP[kSavedCallerPcSlotFromFp] = reinterpret_cast<RawObject*>((argc << 2) | 2);
  FP[kSavedCallerFpSlotFromFp] = reinterpret_cast<RawObject*>(fp_);

  // Load argument descriptor.
  argdesc = arguments_descriptor.raw();

  // Ready to start executing bytecode. Load entry point and corresponding
  // object pool.
  pc = reinterpret_cast<uint32_t*>(code.raw()->ptr()->entry_point_);
  pp = code.object_pool()->ptr();

  // Cache some frequently used values in the frame.
  RawBool* true_value = Bool::True().raw();
  RawBool* false_value = Bool::False().raw();
  RawObject* null_value = Object::null();
  RawObject* empty_context = thread->isolate()->object_store()->empty_context();

#if defined(DEBUG)
  Function& function_h = Function::Handle();
#endif

  // Enter the dispatch loop.
  DISPATCH();

  // Bytecode handlers (see constants_dbc.h for bytecode descriptions).
  {
    BYTECODE(Entry, A_B_C);
    const uint8_t num_fixed_params = rA;
    const uint16_t num_locals = rB;
    const uint16_t context_reg = rC;

    // Decode arguments descriptor.
    const intptr_t pos_count = Smi::Value(*reinterpret_cast<RawSmi**>(
        reinterpret_cast<uword>(argdesc->ptr()) +
        Array::element_offset(ArgumentsDescriptor::kPositionalCountIndex)));

    // Check that we got the right number of positional parameters.
    if (pos_count != num_fixed_params) {
      // Mismatch can only occur if current function is a closure.
      goto ClosureNoSuchMethod;
    }

    // Initialize locals with null and set current context variable to
    // empty context.
    {
      RawObject** L = FP;
      for (intptr_t i = 0; i < num_locals; i++) {
        L[i] = null_value;
      }
      L[context_reg] = empty_context;
      SP = FP + num_locals - 1;
    }

    DISPATCH();
  }

  {
    BYTECODE(EntryOptimized, A_D);
    const uint8_t num_fixed_params = rA;
    const uint16_t num_registers = rD;

    // Decode arguments descriptor.
    const intptr_t pos_count = Smi::Value(*reinterpret_cast<RawSmi**>(
        reinterpret_cast<uword>(argdesc->ptr()) +
        Array::element_offset(ArgumentsDescriptor::kPositionalCountIndex)));

    // Check that we got the right number of positional parameters.
    if (pos_count != num_fixed_params) {
      // Mismatch can only occur if current function is a closure.
      goto ClosureNoSuchMethod;
    }

    // Reserve space for registers used by the optimized code.
    SP = FP + num_registers - 1;

    DISPATCH();
  }

  {
    BYTECODE(EntryOptional, A_B_C);
    const uint16_t num_fixed_params = rA;
    const uint16_t num_opt_pos_params = rB;
    const uint16_t num_opt_named_params = rC;
    const intptr_t min_num_pos_args = num_fixed_params;
    const intptr_t max_num_pos_args = num_fixed_params + num_opt_pos_params;

    // Decode arguments descriptor.
    const intptr_t arg_count = Smi::Value(*reinterpret_cast<RawSmi**>(
        reinterpret_cast<uword>(argdesc->ptr()) +
        Array::element_offset(ArgumentsDescriptor::kCountIndex)));
    const intptr_t pos_count = Smi::Value(*reinterpret_cast<RawSmi**>(
        reinterpret_cast<uword>(argdesc->ptr()) +
        Array::element_offset(ArgumentsDescriptor::kPositionalCountIndex)));
    const intptr_t named_count = (arg_count - pos_count);

    // Check that got the right number of positional parameters.
    if ((min_num_pos_args > pos_count) || (pos_count > max_num_pos_args)) {
      goto ClosureNoSuchMethod;
    }

    // Copy all passed position arguments.
    RawObject** first_arg = FrameArguments(FP, arg_count);
    memmove(FP, first_arg, pos_count * kWordSize);

    if (num_opt_named_params != 0) {
      // This is a function with named parameters.
      // Walk the list of named parameters and their
      // default values encoded as pairs of LoadConstant instructions that
      // follows the entry point and find matching values via arguments
      // descriptor.
      RawObject** argdesc_data = argdesc->ptr()->data();

      intptr_t i = named_count - 1;  // argument position
      intptr_t j = num_opt_named_params - 1;  // parameter position
      while ((j >= 0) && (i >= 0)) {
        // Fetch formal parameter information: name, default value, target slot.
        const uint32_t load_name = pc[2 * j];
        const uint32_t load_value = pc[2 * j + 1];
        ASSERT(Bytecode::DecodeOpcode(load_name) == Bytecode::kLoadConstant);
        ASSERT(Bytecode::DecodeOpcode(load_value) == Bytecode::kLoadConstant);
        const uint8_t reg = Bytecode::DecodeA(load_name);
        ASSERT(reg == Bytecode::DecodeA(load_value));

        RawString* name = static_cast<RawString*>(
            LOAD_CONSTANT(Bytecode::DecodeD(load_name)));
        if (name == argdesc_data[ArgumentsDescriptor::name_index(i)]) {
          // Parameter was passed. Fetch passed value.
          const intptr_t arg_index = Smi::Value(static_cast<RawSmi*>(
              argdesc_data[ArgumentsDescriptor::position_index(i)]));
          FP[reg] = first_arg[arg_index];
          i--;  // Consume passed argument.
        } else {
          // Parameter was not passed. Fetch default value.
          FP[reg] = LOAD_CONSTANT(Bytecode::DecodeD(load_value));
        }
        j--;  // Next formal parameter.
      }

      // If we have unprocessed formal parameters then initialize them all
      // using default values.
      while (j >= 0) {
        const uint32_t load_name = pc[2 * j];
        const uint32_t load_value = pc[2 * j + 1];
        ASSERT(Bytecode::DecodeOpcode(load_name) == Bytecode::kLoadConstant);
        ASSERT(Bytecode::DecodeOpcode(load_value) == Bytecode::kLoadConstant);
        const uint8_t reg = Bytecode::DecodeA(load_name);
        ASSERT(reg == Bytecode::DecodeA(load_value));

        FP[reg] = LOAD_CONSTANT(Bytecode::DecodeD(load_value));
        j--;
      }

      // If we have unprocessed passed arguments that means we have mismatch
      // between formal parameters and concrete arguments. This can only
      // occur if the current function is a closure.
      if (i != -1) {
        goto ClosureNoSuchMethod;
      }

      // Skip LoadConstant-s encoding information about named parameters.
      pc += num_opt_named_params * 2;

      // SP points past copied arguments.
      SP = FP + num_fixed_params + num_opt_named_params - 1;
    } else {
      ASSERT(num_opt_pos_params != 0);
      if (named_count != 0) {
        // Function can't have both named and optional positional parameters.
        // This kind of mismatch can only occur if the current function
        // is a closure.
        goto ClosureNoSuchMethod;
      }

      // Process the list of default values encoded as a sequence of
      // LoadConstant instructions after EntryOpt bytecode.
      // Execute only those that correspond to parameters the were not passed.
      for (intptr_t i = pos_count - num_fixed_params;
           i < num_opt_pos_params;
           i++) {
        const uint32_t load_value = pc[i];
        ASSERT(Bytecode::DecodeOpcode(load_value) == Bytecode::kLoadConstant);
#if defined(DEBUG)
        const uint8_t reg = Bytecode::DecodeA(load_value);
        ASSERT((num_fixed_params + i) == reg);
#endif
        FP[num_fixed_params + i] = LOAD_CONSTANT(Bytecode::DecodeD(load_value));
      }

      // Skip LoadConstant-s encoding default values for optional positional
      // parameters.
      pc += num_opt_pos_params;

      // SP points past the last copied parameter.
      SP = FP + max_num_pos_args - 1;
    }

    DISPATCH();
  }

  {
    BYTECODE(Frame, A_D);
    // Initialize locals with null and increment SP.
    const uint16_t num_locals = rD;
    for (intptr_t i = 1; i <= num_locals; i++) {
      SP[i] = null_value;
    }
    SP += num_locals;

    DISPATCH();
  }

  {
    BYTECODE(SetFrame, A);
    SP = FP + rA - 1;
    DISPATCH();
  }

  {
    BYTECODE(Compile, 0);
    FP[0] = FrameFunction(FP);
    FP[1] = 0;
    Exit(thread, FP, FP + 2, pc);
    NativeArguments args(thread, 1, FP, FP + 1);
    INVOKE_RUNTIME(DRT_CompileFunction, args);
    {
      // Function should be compiled now, dispatch to its entry point.
      RawCode* code = FrameFunction(FP)->ptr()->code_;
      SimulatorHelpers::SetFrameCode(FP, code);
      pp = code->ptr()->object_pool_->ptr();
      pc = reinterpret_cast<uint32_t*>(code->ptr()->entry_point_);
    }
    DISPATCH();
  }

  {
    BYTECODE(HotCheck, A_D);
    const uint8_t increment = rA;
    const uint16_t threshold = rD;
    RawFunction* f =  FrameFunction(FP);
    int32_t counter = f->ptr()->usage_counter_;
    // Note: we don't increment usage counter in the prologue of optimized
    // functions.
    if (increment) {
      counter += increment;
      f->ptr()->usage_counter_ = counter;
    }
    if (counter >= threshold) {
      FP[0] = f;
      FP[1] = 0;
      Exit(thread, FP, FP + 2, pc);
      NativeArguments args(thread, 1, FP, FP + 1);
      INVOKE_RUNTIME(DRT_OptimizeInvokedFunction, args);
      {
        // DRT_OptimizeInvokedFunction returns the code object to execute.
        ASSERT(FP[1]->GetClassId() == kCodeCid);
        RawCode* code = static_cast<RawCode*>(FP[1]);
        SimulatorHelpers::SetFrameCode(FP, code);
        pp = code->ptr()->object_pool_->ptr();
        pc = reinterpret_cast<uint32_t*>(code->ptr()->entry_point_);
      }
    }
    DISPATCH();
  }

  {
    BYTECODE(CheckStack, A);
    {
      if (reinterpret_cast<uword>(SP) >= thread->stack_limit()) {
        Exit(thread, FP, SP + 1, pc);
        NativeArguments args(thread, 0, NULL, NULL);
        INVOKE_RUNTIME(DRT_StackOverflow, args);
      }
    }
    DISPATCH();
  }

  {
    BYTECODE(DebugStep, A);
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }
    DISPATCH();
  }

  {
    BYTECODE(DebugBreak, A);
#if !defined(PRODUCT)
    {
      const uint32_t original_bc =
          static_cast<uint32_t>(reinterpret_cast<uintptr_t>(
              thread->isolate()->debugger()->GetPatchedStubAddress(
                  reinterpret_cast<uword>(pc))));

      SP[1] = null_value;
      Exit(thread, FP, SP + 2, pc);
      NativeArguments args(thread, 0, NULL, SP + 1);
      INVOKE_RUNTIME(DRT_BreakpointRuntimeHandler, args)
      DISPATCH_OP(original_bc);
    }
#else
    // There should be no debug breaks in product mode.
    UNREACHABLE();
#endif
    DISPATCH();
  }

  {
    BYTECODE(InstantiateType, A_D);
    RawObject* type = LOAD_CONSTANT(rD);
    SP[1] = type;
    SP[2] = SP[0];
    SP[0] = null_value;
    Exit(thread, FP, SP + 3, pc);
    {
      NativeArguments args(thread, 2, SP + 1, SP);
      INVOKE_RUNTIME(DRT_InstantiateType, args);
    }
    DISPATCH();
  }

  {
    BYTECODE(InstantiateTypeArgumentsTOS, A_D);
    RawTypeArguments* type_arguments =
        static_cast<RawTypeArguments*>(LOAD_CONSTANT(rD));

    RawObject* instantiator = SP[0];
    // If the instantiator is null and if the type argument vector
    // instantiated from null becomes a vector of dynamic, then use null as
    // the type arguments.
    if (rA == 0 || null_value != instantiator) {
      // First lookup in the cache.
      RawArray* instantiations = type_arguments->ptr()->instantiations_;
      for (intptr_t i = 0;
           instantiations->ptr()->data()[i] != NULL;  // kNoInstantiator
           i += 2) {
        if (instantiations->ptr()->data()[i] == instantiator) {
          // Found in the cache.
          SP[0] = instantiations->ptr()->data()[i + 1];
          goto InstantiateTypeArgumentsTOSDone;
        }
      }

      // Cache lookup failed, call runtime.
      SP[1] = type_arguments;
      SP[2] = instantiator;

      Exit(thread, FP, SP + 3, pc);
      NativeArguments args(thread, 2, SP + 1, SP);
      INVOKE_RUNTIME(DRT_InstantiateTypeArguments, args);
    }

  InstantiateTypeArgumentsTOSDone:
    DISPATCH();
  }

  {
    BYTECODE(Throw, A);
    {
      SP[1] = 0;  // Space for result.
      Exit(thread, FP, SP + 2, pc);
      if (rA == 0) {  // Throw
        NativeArguments args(thread, 1, SP, SP + 1);
        INVOKE_RUNTIME(DRT_Throw, args);
      } else {  // ReThrow
        NativeArguments args(thread, 2, SP - 1, SP + 1);
        INVOKE_RUNTIME(DRT_ReThrow, args);
      }
    }
    DISPATCH();
  }

  {
    BYTECODE(Drop1, 0);
    SP--;
    DISPATCH();
  }

  {
    BYTECODE(Drop, 0);
    SP -= rA;
    DISPATCH();
  }

  {
    BYTECODE(DropR, 0);
    RawObject* result = SP[0];
    SP -= rA;
    SP[0] = result;
    DISPATCH();
  }

  {
    BYTECODE(LoadConstant, A_D);
    FP[rA] = LOAD_CONSTANT(rD);
    DISPATCH();
  }

  {
    BYTECODE(PushConstant, __D);
    *++SP = LOAD_CONSTANT(rD);
    DISPATCH();
  }

  {
    BYTECODE(Push, A_X);
    *++SP = FP[rD];
    DISPATCH();
  }

  {
    BYTECODE(Move, A_X);
    FP[rA] = FP[rD];
    DISPATCH();
  }

  {
    BYTECODE(Swap, A_X);
    RawObject* tmp = FP[rD];
    FP[rD] = FP[rA];
    FP[rA] = tmp;
    DISPATCH();
  }

  {
    BYTECODE(StoreLocal, A_X);
    FP[rD] = *SP;
    DISPATCH();
  }

  {
    BYTECODE(PopLocal, A_X);
    FP[rD] = *SP--;
    DISPATCH();
  }

  {
    BYTECODE(MoveSpecial, A_D);
    FP[rA] = special_[rD];
    DISPATCH();
  }

  {
    BYTECODE(BooleanNegateTOS, 0);
    SP[0] = (SP[0] == true_value) ? false_value : true_value;
    DISPATCH();
  }

  {
    BYTECODE(BooleanNegate, A_D);
    FP[rA] = (FP[rD] == true_value) ? false_value : true_value;
    DISPATCH();
  }

  {
    BYTECODE(StaticCall, A_D);

    // Check if single stepping.
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }

    // Invoke target function.
    {
      const uint16_t argc = rA;
      RawObject** call_base = SP - argc;
      RawObject** call_top = SP;  // *SP contains function
      argdesc = static_cast<RawArray*>(LOAD_CONSTANT(rD));
      Invoke(thread, call_base, call_top, &pp, &pc, &FP, &SP);
    }

    DISPATCH();
  }

  {
    BYTECODE(InstanceCall1, A_D);

    // Check if single stepping.
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }

    {
      const uint16_t argc = rA;
      const uint16_t kidx = rD;

      RawObject** call_base = SP - argc + 1;
      RawObject** call_top = SP + 1;

      RawICData* icdata = RAW_CAST(ICData, LOAD_CONSTANT(kidx));
      SimulatorHelpers::IncrementUsageCounter(
          RAW_CAST(Function, icdata->ptr()->owner_));
      InstanceCall1(
          thread, icdata, call_base, call_top, &argdesc, &pp, &pc, &FP, &SP);
    }

    DISPATCH();
  }

  {
    BYTECODE(InstanceCall2, A_D);
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }

    {
      const uint16_t argc = rA;
      const uint16_t kidx = rD;

      RawObject** call_base = SP - argc + 1;
      RawObject** call_top = SP + 1;

      RawICData* icdata = RAW_CAST(ICData, LOAD_CONSTANT(kidx));
      SimulatorHelpers::IncrementUsageCounter(
          RAW_CAST(Function, icdata->ptr()->owner_));
      InstanceCall2(
          thread, icdata, call_base, call_top, &argdesc, &pp, &pc, &FP, &SP);
    }

    DISPATCH();
  }

  {
    BYTECODE(InstanceCall1Opt, A_D);

    {
      const uint16_t argc = rA;
      const uint16_t kidx = rD;

      RawObject** call_base = SP - argc + 1;
      RawObject** call_top = SP + 1;

      RawICData* icdata = RAW_CAST(ICData, LOAD_CONSTANT(kidx));
      SimulatorHelpers::IncrementUsageCounter(FrameFunction(FP));
      InstanceCall1(
          thread, icdata, call_base, call_top, &argdesc, &pp, &pc, &FP, &SP);
    }

    DISPATCH();
  }

  {
    BYTECODE(InstanceCall2Opt, A_D);

    {
      const uint16_t argc = rA;
      const uint16_t kidx = rD;

      RawObject** call_base = SP - argc + 1;
      RawObject** call_top = SP + 1;

      RawICData* icdata = RAW_CAST(ICData, LOAD_CONSTANT(kidx));
      SimulatorHelpers::IncrementUsageCounter(FrameFunction(FP));
      InstanceCall2(
          thread, icdata, call_base, call_top, &argdesc, &pp, &pc, &FP, &SP);
    }

    DISPATCH();
  }

  {
    BYTECODE(NativeBootstrapCall, 0);
    RawFunction* function = FrameFunction(FP);
    RawObject** incoming_args =
        (function->ptr()->num_optional_parameters_ == 0)
            ? FrameArguments(FP, function->ptr()->num_fixed_parameters_)
            : FP;

    SimulatorBootstrapNativeCall native_target =
        reinterpret_cast<SimulatorBootstrapNativeCall>(SP[-1]);
    intptr_t argc_tag = reinterpret_cast<intptr_t>(SP[-0]);
    SP[-0] = 0;  // Note: argc_tag is not smi-tagged.
    SP[-1] = null_value;
    Exit(thread, FP, SP + 1, pc);
    NativeArguments args(thread, argc_tag, incoming_args, SP - 1);
    INVOKE_NATIVE(native_target, args);
    SP -= 1;
    DISPATCH();
  }

  {
    BYTECODE(NativeCall, 0);
    RawFunction* function = FrameFunction(FP);
    RawObject** incoming_args =
        (function->ptr()->num_optional_parameters_ == 0)
            ? FrameArguments(FP, function->ptr()->num_fixed_parameters_)
            : FP;

    Dart_NativeFunction native_target =
        reinterpret_cast<Dart_NativeFunction>(SP[-1]);
    intptr_t argc_tag = reinterpret_cast<intptr_t>(SP[-0]);
    SP[-0] = 0;  // argc_tag is not smi tagged!
    SP[-1] = null_value;
    Exit(thread, FP, SP + 1, pc);
    NativeArguments args(thread, argc_tag, incoming_args, SP - 1);
    INVOKE_NATIVE_WRAPPER(native_target, args);
    SP -= 1;
    DISPATCH();
  }

  {
    BYTECODE(AddTOS, A_B_C);
    SMI_FASTPATH_TOS(intptr_t, SignedAddWithOverflow);
    DISPATCH();
  }
  {
    BYTECODE(SubTOS, A_B_C);
    SMI_FASTPATH_TOS(intptr_t, SignedSubWithOverflow);
    DISPATCH();
  }
  {
    BYTECODE(MulTOS, A_B_C);
    SMI_FASTPATH_TOS(intptr_t, SMI_MUL);
    DISPATCH();
  }
  {
    BYTECODE(BitOrTOS, A_B_C);
    SMI_FASTPATH_TOS(intptr_t, SMI_BITOR);
    DISPATCH();
  }
  {
    BYTECODE(BitAndTOS, A_B_C);
    SMI_FASTPATH_TOS(intptr_t, SMI_BITAND);
    DISPATCH();
  }
  {
    BYTECODE(EqualTOS, A_B_C);
    SMI_FASTPATH_TOS(RawObject*, SMI_EQ);
    DISPATCH();
  }
  {
    BYTECODE(LessThanTOS, A_B_C);
    SMI_FASTPATH_TOS(RawObject*, SMI_LT);
    DISPATCH();
  }
  {
    BYTECODE(GreaterThanTOS, A_B_C);
    SMI_FASTPATH_TOS(RawObject*, SMI_GT);
    DISPATCH();
  }

  // Return and return like instructions (Instrinsic).
  {
    RawObject* result;  // result to return to the caller.

    BYTECODE(Intrinsic, A);
    // Try invoking intrinsic handler. If it succeeds (returns true)
    // then just return the value it returned to the caller.
    result = null_value;
    if (!intrinsics_[rA](thread, FP, &result)) {
      DISPATCH();
    }
    goto ReturnImpl;

    BYTECODE(Return, A);
    result = FP[rA];
    goto ReturnImpl;

    BYTECODE(ReturnTOS, 0);
    result = *SP;
    // Fall through to the ReturnImpl.

  ReturnImpl:
    // Restore caller PC.
    pc = SavedCallerPC(FP);

    // Check if it is a fake PC marking the entry frame.
    if ((reinterpret_cast<uword>(pc) & 2) != 0) {
      const intptr_t argc = reinterpret_cast<uword>(pc) >> 2;
      fp_ = sp_ =
          reinterpret_cast<RawObject**>(FrameArguments(FP, argc + 1)[0]);
      thread->set_top_exit_frame_info(reinterpret_cast<uword>(sp_));
      thread->set_top_resource(top_resource);
      thread->set_vm_tag(vm_tag);
      return result;
    }

    // Look at the caller to determine how many arguments to pop.
    const uint8_t argc = Bytecode::DecodeArgc(pc[-1]);

    // Restore SP, FP and PP. Push result and dispatch.
    SP = FrameArguments(FP, argc);
    FP = SavedCallerFP(FP);
    pp = SimulatorHelpers::FrameCode(FP)->ptr()->object_pool_->ptr();
    *SP = result;
    DISPATCH();
  }

  {
    BYTECODE(StoreStaticTOS, A_D);
    RawField* field = reinterpret_cast<RawField*>(LOAD_CONSTANT(rD));
    RawInstance* value = static_cast<RawInstance*>(*SP--);
    field->StorePointer(&field->ptr()->value_.static_value_, value);
    DISPATCH();
  }

  {
    BYTECODE(PushStatic, A_D);
    RawField* field = reinterpret_cast<RawField*>(LOAD_CONSTANT(rD));
    // Note: field is also on the stack, hence no increment.
    *SP = field->ptr()->value_.static_value_;
    DISPATCH();
  }

  {
    BYTECODE(StoreField, A_B_C);
    const uint16_t offset_in_words = rB;
    const uint16_t value_reg = rC;

    RawInstance* instance = reinterpret_cast<RawInstance*>(FP[rA]);
    RawObject* value = reinterpret_cast<RawObject*>(FP[value_reg]);

    instance->StorePointer(
        reinterpret_cast<RawObject**>(instance->ptr()) + offset_in_words,
        value);
    DISPATCH();
  }

  {
    BYTECODE(StoreFieldTOS, A_D);
    const uint16_t offset_in_words = rD;
    RawInstance* instance = reinterpret_cast<RawInstance*>(SP[-1]);
    RawObject* value = reinterpret_cast<RawObject*>(SP[0]);
    SP -= 2;  // Drop instance and value.
    instance->StorePointer(
        reinterpret_cast<RawObject**>(instance->ptr()) + offset_in_words,
        value);

    DISPATCH();
  }

  {
    BYTECODE(LoadField, A_B_C);
    const uint16_t instance_reg = rB;
    const uint16_t offset_in_words = rC;
    RawInstance* instance = reinterpret_cast<RawInstance*>(FP[instance_reg]);
    FP[rA] = reinterpret_cast<RawObject**>(instance->ptr())[offset_in_words];
    DISPATCH();
  }

  {
    BYTECODE(LoadFieldTOS, A_D);
    const uint16_t offset_in_words = rD;
    RawInstance* instance = static_cast<RawInstance*>(SP[0]);
    SP[0] = reinterpret_cast<RawObject**>(instance->ptr())[offset_in_words];
    DISPATCH();
  }

  {
    BYTECODE(InitStaticTOS, A);
    RawField* field = static_cast<RawField*>(*SP--);
    RawObject* value = field->ptr()->value_.static_value_;
    if ((value == Object::sentinel().raw()) ||
        (value == Object::transition_sentinel().raw())) {
      // Note: SP[1] already contains the field object.
      SP[2] = 0;
      Exit(thread, FP, SP + 3, pc);
      NativeArguments args(thread, 1, SP + 1, SP + 2);
      INVOKE_RUNTIME(DRT_InitStaticField, args);
    }
    DISPATCH();
  }

  // TODO(vegorov) allocation bytecodes can benefit from the new-space
  // allocation fast-path that does not transition into the runtime system.
  {
    BYTECODE(AllocateContext, A_D);
    const uint16_t num_context_variables = rD;
    {
      *++SP = 0;
      SP[1] = Smi::New(num_context_variables);
      Exit(thread, FP, SP + 2, pc);
      NativeArguments args(thread, 1, SP + 1, SP);
      INVOKE_RUNTIME(DRT_AllocateContext, args);
    }
    DISPATCH();
  }

  {
    BYTECODE(CloneContext, A);
    {
      SP[1] = SP[0];  // Context to clone.
      Exit(thread, FP, SP + 2, pc);
      NativeArguments args(thread, 1, SP + 1, SP);
      INVOKE_RUNTIME(DRT_CloneContext, args);
    }
    DISPATCH();
  }

  {
    BYTECODE(Allocate, A_D);
    SP[1] = 0;  // Space for the result.
    SP[2] = LOAD_CONSTANT(rD);  // Class object.
    SP[3] = null_value;  // Type arguments.
    Exit(thread, FP, SP + 4, pc);
    NativeArguments args(thread, 2, SP + 2, SP + 1);
    INVOKE_RUNTIME(DRT_AllocateObject, args);
    SP++;  // Result is in SP[1].
    DISPATCH();
  }

  {
    BYTECODE(AllocateT, 0);
    SP[1] = SP[-0];  // Class object.
    SP[2] = SP[-1];  // Type arguments
    Exit(thread, FP, SP + 3, pc);
    NativeArguments args(thread, 2, SP + 1, SP - 1);
    INVOKE_RUNTIME(DRT_AllocateObject, args);
    SP -= 1;  // Result is in SP - 1.
    DISPATCH();
  }

  {
    BYTECODE(CreateArrayTOS, 0);
    SP[1] = SP[-0];  // Length.
    SP[2] = SP[-1];  // Type.
    Exit(thread, FP, SP + 3, pc);
    NativeArguments args(thread, 2, SP + 1, SP - 1);
    INVOKE_RUNTIME(DRT_AllocateArray, args);
    SP -= 1;
    DISPATCH();
  }

  {
    BYTECODE(AssertAssignable, A_D);  // Stack: instance, type args, type, name
    RawObject** args = SP - 3;
    if (args[0] != null_value) {
      const AbstractType& dst_type =
          AbstractType::Handle(static_cast<RawAbstractType*>(args[2]));
      if (dst_type.IsMalformedOrMalbounded()) {
        SP[1] = args[0];  // instance.
        SP[2] = args[3];  // name.
        SP[3] = args[2];  // type.
        Exit(thread, FP, SP + 4, pc);
        NativeArguments args(thread, 3, SP + 1, SP - 3);
        INVOKE_RUNTIME(DRT_BadTypeError, args);
        UNREACHABLE();
      }

      RawSubtypeTestCache* cache =
          static_cast<RawSubtypeTestCache*>(LOAD_CONSTANT(rD));
      if (cache != null_value) {
        RawInstance* instance = static_cast<RawInstance*>(args[0]);
        RawTypeArguments* instantiator_type_arguments =
            static_cast<RawTypeArguments*>(args[1]);

        const intptr_t cid = SimulatorHelpers::GetClassId(instance);

        RawTypeArguments* instance_type_arguments =
            static_cast<RawTypeArguments*>(null_value);
        RawObject* instance_cid_or_function;
        if (cid == kClosureCid) {
          RawClosure* closure = static_cast<RawClosure*>(instance);
          instance_type_arguments = closure->ptr()->type_arguments_;
          instance_cid_or_function = closure->ptr()->function_;
        } else {
          instance_cid_or_function = Smi::New(cid);

          RawClass* instance_class =
              thread->isolate()->class_table()->At(cid);
          if (instance_class->ptr()->num_type_arguments_ < 0) {
            goto AssertAssignableCallRuntime;
          } else if (instance_class->ptr()->num_type_arguments_ > 0) {
            instance_type_arguments = reinterpret_cast<RawTypeArguments**>(
                instance
                    ->ptr())[instance_class->ptr()
                                 ->type_arguments_field_offset_in_words_];
          }
        }

        for (RawObject** entries = cache->ptr()->cache_->ptr()->data();
             entries[0] != null_value;
             entries += SubtypeTestCache::kTestEntryLength) {
          if ((entries[SubtypeTestCache::kInstanceClassIdOrFunction] ==
                  instance_cid_or_function) &&
              (entries[SubtypeTestCache::kInstanceTypeArguments] ==
                  instance_type_arguments) &&
              (entries[SubtypeTestCache::kInstantiatorTypeArguments] ==
                  instantiator_type_arguments)) {
            if (true_value == entries[SubtypeTestCache::kTestResult]) {
              goto AssertAssignableOk;
            } else {
              break;
            }
          }
        }
      }

    AssertAssignableCallRuntime:
      SP[1] = args[0];  // instance
      SP[2] = args[2];  // type
      SP[3] = args[1];  // type args
      SP[4] = args[3];  // name
      SP[5] = cache;
      Exit(thread, FP, SP + 6, pc);
      NativeArguments args(thread, 5, SP + 1, SP - 3);
      INVOKE_RUNTIME(DRT_TypeCheck, args);
    }

  AssertAssignableOk:
    SP -= 3;
    DISPATCH();
  }

  {
    BYTECODE(AssertBoolean, A);
    RawObject* value = SP[0];
    if (rA) {  // Should we perform type check?
      if ((value == true_value) || (value == false_value)) {
        goto AssertBooleanOk;
      }
    } else if (value != null_value) {
      goto AssertBooleanOk;
    }

    // Assertion failed.
    {
      SP[1] = SP[0];  // instance
      Exit(thread, FP, SP + 2, pc);
      NativeArguments args(thread, 1, SP + 1, SP);
      INVOKE_RUNTIME(DRT_NonBoolTypeError, args);
    }

  AssertBooleanOk:
    DISPATCH();
  }

  {
    BYTECODE(IfEqStrictTOS, 0);
    SP -= 2;
    if (SP[1] != SP[2]) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfNeStrictTOS, 0);
    SP -= 2;
    if (SP[1] == SP[2]) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfEqStrictNumTOS, 0);
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }

    SP -= 2;
    if (!SimulatorHelpers::IsStrictEqualWithNumberCheck(SP[1], SP[2])) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfNeStrictNumTOS, 0);
    if (thread->isolate()->single_step()) {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments args(thread, 0, NULL, NULL);
      INVOKE_RUNTIME(DRT_SingleStepHandler, args);
    }

    SP -= 2;
    if (SimulatorHelpers::IsStrictEqualWithNumberCheck(SP[1], SP[2])) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfEqStrict, A_D);
    RawObject* lhs = FP[rA];
    RawObject* rhs = FP[rD];
    if (lhs != rhs) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfNeStrict, A_D);
    RawObject* lhs = FP[rA];
    RawObject* rhs = FP[rD];
    if (lhs == rhs) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfEqStrictNum, A_D);
    RawObject* lhs = FP[rA];
    RawObject* rhs = FP[rD];
    if (!SimulatorHelpers::IsStrictEqualWithNumberCheck(lhs, rhs)) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(IfNeStrictNum, A_D);
    RawObject* lhs = FP[rA];
    RawObject* rhs = FP[rD];
    if (SimulatorHelpers::IsStrictEqualWithNumberCheck(lhs, rhs)) {
      pc++;
    }
    DISPATCH();
  }

  {
    BYTECODE(Jump, 0);
    const int32_t target = static_cast<int32_t>(op) >> 8;
    pc += (target - 1);
    DISPATCH();
  }

  {
    BYTECODE(LoadClassId, A_D);
    const uint16_t object_reg = rD;
    RawObject* obj = static_cast<RawObject*>(FP[object_reg]);
    FP[rA] = SimulatorHelpers::GetClassIdAsSmi(obj);
    DISPATCH();
  }

  {
    BYTECODE(LoadClassIdTOS, 0);
    RawObject* obj = static_cast<RawObject*>(SP[0]);
    SP[0] = SimulatorHelpers::GetClassIdAsSmi(obj);
    DISPATCH();
  }

  {
    BYTECODE(StoreIndexedTOS, 0);
    SP -= 3;
    RawArray* array = static_cast<RawArray*>(SP[1]);
    RawSmi* index = static_cast<RawSmi*>(SP[2]);
    RawObject* value = SP[3];
    ASSERT(array->GetClassId() == kArrayCid);
    ASSERT(!index->IsHeapObject());
    ASSERT(SimulatorHelpers::CheckIndex(index, array->ptr()->length_));
    array->StorePointer(array->ptr()->data() + Smi::Value(index), value);
    DISPATCH();
  }

  {
    BYTECODE(StoreIndexed, A_B_C);
    RawArray* array = static_cast<RawArray*>(FP[rA]);
    RawSmi* index = static_cast<RawSmi*>(FP[rB]);
    RawObject* value = FP[rC];
    ASSERT(array->GetClassId() == kArrayCid);
    ASSERT(!index->IsHeapObject());
    ASSERT(SimulatorHelpers::CheckIndex(index, array->ptr()->length_));
    array->StorePointer(array->ptr()->data() + Smi::Value(index), value);
    DISPATCH();
  }

  {
    BYTECODE(Deopt, A_D);
    const uint16_t deopt_id = rD;
    if (deopt_id == 0) {  // Lazy deoptimization.
      // Preserve result of the previous call.
      // TODO(vegorov) we could have actually included result into the
      // deoptimization environment because it is passed through the stack.
      // If we do then we could remove special result handling from this code.
      RawObject* result = SP[0];

      // Leaf runtime function DeoptimizeCopyFrame expects a Dart frame.
      // The code in this frame may not cause GC.
      // DeoptimizeCopyFrame and DeoptimizeFillFrame are leaf runtime calls.
      EnterSyntheticFrame(&FP, &SP, pc - 1);
      const intptr_t frame_size_in_bytes =
          DLRT_DeoptimizeCopyFrame(reinterpret_cast<uword>(FP),
                                   /*is_lazy_deopt=*/1);
      LeaveSyntheticFrame(&FP, &SP);

      SP = FP + (frame_size_in_bytes / kWordSize);
      EnterSyntheticFrame(&FP, &SP, pc - 1);
      DLRT_DeoptimizeFillFrame(reinterpret_cast<uword>(FP));

      // We are now inside a valid frame.
      {
        *++SP = result;  // Preserve result (call below can cause GC).
        *++SP = 0;  // Space for the result: number of materialization args.
        Exit(thread, FP, SP + 1, /*pc=*/0);
        NativeArguments native_args(thread, 0, SP, SP);
        INVOKE_RUNTIME(DRT_DeoptimizeMaterialize, native_args);
      }
      const intptr_t materialization_arg_count =
          Smi::Value(RAW_CAST(Smi, *SP--));
      result = *SP--;  // Reload the result. It might have been relocated by GC.

      // Restore caller PC.
      pc = SavedCallerPC(FP);

      // Check if it is a fake PC marking the entry frame.
      ASSERT((reinterpret_cast<uword>(pc) & 2) == 0);

      // Restore SP, FP and PP. Push result and dispatch.
      // Note: unlike in a normal return sequence we don't need to drop
      // arguments - those are not part of the innermost deoptimization
      // environment they were dropped by FlowGraphCompiler::RecordAfterCall.
      SP = FrameArguments(FP, materialization_arg_count);
      FP = SavedCallerFP(FP);
      pp = SimulatorHelpers::FrameCode(FP)->ptr()->object_pool_->ptr();
      *SP = result;
    } else {
      UNIMPLEMENTED();
    }
    DISPATCH();
  }

  {
    BYTECODE(Trap, 0);
    UNIMPLEMENTED();
    DISPATCH();
  }

  // Helper used to handle noSuchMethod on closures.
  {
  ClosureNoSuchMethod:
#if defined(DEBUG)
    function_h ^= FrameFunction(FP);
    ASSERT(function_h.IsClosureFunction());
#endif

    // Restore caller context as we are going to throw NoSuchMethod.
    pc = SavedCallerPC(FP);

    const bool has_dart_caller = (reinterpret_cast<uword>(pc) & 2) == 0;
    const intptr_t argc = has_dart_caller
                              ? Bytecode::DecodeArgc(pc[-1])
                              : (reinterpret_cast<uword>(pc) >> 2);

    SP = FrameArguments(FP, 0);
    RawObject** args = SP - argc;
    FP = SavedCallerFP(FP);
    if (has_dart_caller) {
      pp = SimulatorHelpers::FrameCode(FP)->ptr()->object_pool_->ptr();
    }

    *++SP = null_value;
    *++SP = args[0];  // Closure object.
    *++SP = argdesc;
    *++SP = null_value;  // Array of arguments (will be filled).

    // Allocate array of arguments.
    {
      SP[1] = Smi::New(argc);  // length
      SP[2] = null_value;      // type
      Exit(thread, FP, SP + 3, pc);
      NativeArguments native_args(thread, 2, SP + 1, SP);
      INVOKE_RUNTIME(DRT_AllocateArray, native_args);

      // Copy arguments into the newly allocated array.
      RawArray* array = static_cast<RawArray*>(SP[0]);
      ASSERT(array->GetClassId() == kArrayCid);
      for (intptr_t i = 0; i < argc; i++) {
        array->ptr()->data()[i] = args[i];
      }
    }

    // Invoke noSuchMethod passing down closure, argument descriptor and
    // array of arguments.
    {
      Exit(thread, FP, SP + 1, pc);
      NativeArguments native_args(thread, 3, SP - 2, SP - 3);
      INVOKE_RUNTIME(DRT_InvokeClosureNoSuchMethod, native_args);
      UNREACHABLE();
    }

    DISPATCH();
  }

  // Single dispatch point used by exception handling macros.
  {
  DispatchAfterException:
    DISPATCH();
  }

  UNREACHABLE();
  return 0;
}

void Simulator::Longjmp(uword pc,
                        uword sp,
                        uword fp,
                        RawObject* raw_exception,
                        RawObject* raw_stacktrace,
                        Thread* thread) {
  // Walk over all setjmp buffers (simulated --> C++ transitions)
  // and try to find the setjmp associated with the simulated stack pointer.
  SimulatorSetjmpBuffer* buf = last_setjmp_buffer();
  while ((buf->link() != NULL) && (buf->link()->fp() > fp)) {
    buf = buf->link();
  }
  ASSERT(buf != NULL);
  ASSERT(last_setjmp_buffer() == buf);

  // The C++ caller has not cleaned up the stack memory of C++ frames.
  // Prepare for unwinding frames by destroying all the stack resources
  // in the previous C++ frames.
  StackResource::Unwind(thread);

  // Set the tag.
  thread->set_vm_tag(VMTag::kDartTagId);
  // Clear top exit frame.
  thread->set_top_exit_frame_info(0);

  ASSERT(raw_exception != Object::null());
  sp_ = reinterpret_cast<RawObject**>(sp);
  fp_ = reinterpret_cast<RawObject**>(fp);
  pc_ = pc;
  special_[kExceptionSpecialIndex] = raw_exception;
  special_[kStacktraceSpecialIndex] = raw_stacktrace;
  buf->Longjmp();
  UNREACHABLE();
}

}  // namespace dart


#endif  // defined TARGET_ARCH_DBC