xref: /external/v8/src/crankshaft/arm64/lithium-codegen-arm64.cc

// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/crankshaft/arm64/lithium-codegen-arm64.h"

#include "src/arm64/frames-arm64.h"
#include "src/base/bits.h"
#include "src/code-factory.h"
#include "src/code-stubs.h"
#include "src/crankshaft/arm64/lithium-gap-resolver-arm64.h"
#include "src/crankshaft/hydrogen-osr.h"
#include "src/ic/ic.h"
#include "src/ic/stub-cache.h"

namespace v8 {
namespace internal {


class SafepointGenerator final : public CallWrapper {
 public:
  SafepointGenerator(LCodeGen* codegen,
                     LPointerMap* pointers,
                     Safepoint::DeoptMode mode)
      : codegen_(codegen),
        pointers_(pointers),
        deopt_mode_(mode) { }
  virtual ~SafepointGenerator() { }

  virtual void BeforeCall(int call_size) const { }

  virtual void AfterCall() const {
    codegen_->RecordSafepoint(pointers_, deopt_mode_);
  }

 private:
  LCodeGen* codegen_;
  LPointerMap* pointers_;
  Safepoint::DeoptMode deopt_mode_;
};


#define __ masm()->

// Emit code to branch if the given condition holds.
// The code generated here doesn't modify the flags and they must have
// been set by some prior instructions.
//
// The EmitInverted function simply inverts the condition.
class BranchOnCondition : public BranchGenerator {
 public:
  BranchOnCondition(LCodeGen* codegen, Condition cond)
    : BranchGenerator(codegen),
      cond_(cond) { }

  virtual void Emit(Label* label) const {
    __ B(cond_, label);
  }

  virtual void EmitInverted(Label* label) const {
    if (cond_ != al) {
      __ B(NegateCondition(cond_), label);
    }
  }

 private:
  Condition cond_;
};


// Emit code to compare lhs and rhs and branch if the condition holds.
// This uses MacroAssembler's CompareAndBranch function so it will handle
// converting the comparison to Cbz/Cbnz if the right-hand side is 0.
//
// EmitInverted still compares the two operands but inverts the condition.
class CompareAndBranch : public BranchGenerator {
 public:
  CompareAndBranch(LCodeGen* codegen,
                   Condition cond,
                   const Register& lhs,
                   const Operand& rhs)
    : BranchGenerator(codegen),
      cond_(cond),
      lhs_(lhs),
      rhs_(rhs) { }

  virtual void Emit(Label* label) const {
    __ CompareAndBranch(lhs_, rhs_, cond_, label);
  }

  virtual void EmitInverted(Label* label) const {
    __ CompareAndBranch(lhs_, rhs_, NegateCondition(cond_), label);
  }

 private:
  Condition cond_;
  const Register& lhs_;
  const Operand& rhs_;
};


// Test the input with the given mask and branch if the condition holds.
// If the condition is 'eq' or 'ne' this will use MacroAssembler's
// TestAndBranchIfAllClear and TestAndBranchIfAnySet so it will handle the
// conversion to Tbz/Tbnz when possible.
class TestAndBranch : public BranchGenerator {
 public:
  TestAndBranch(LCodeGen* codegen,
                Condition cond,
                const Register& value,
                uint64_t mask)
    : BranchGenerator(codegen),
      cond_(cond),
      value_(value),
      mask_(mask) { }

  virtual void Emit(Label* label) const {
    switch (cond_) {
      case eq:
        __ TestAndBranchIfAllClear(value_, mask_, label);
        break;
      case ne:
        __ TestAndBranchIfAnySet(value_, mask_, label);
        break;
      default:
        __ Tst(value_, mask_);
        __ B(cond_, label);
    }
  }

  virtual void EmitInverted(Label* label) const {
    // The inverse of "all clear" is "any set" and vice versa.
    switch (cond_) {
      case eq:
        __ TestAndBranchIfAnySet(value_, mask_, label);
        break;
      case ne:
        __ TestAndBranchIfAllClear(value_, mask_, label);
        break;
      default:
        __ Tst(value_, mask_);
        __ B(NegateCondition(cond_), label);
    }
  }

 private:
  Condition cond_;
  const Register& value_;
  uint64_t mask_;
};


// Test the input and branch if it is non-zero and not a NaN.
class BranchIfNonZeroNumber : public BranchGenerator {
 public:
  BranchIfNonZeroNumber(LCodeGen* codegen, const FPRegister& value,
                        const FPRegister& scratch)
    : BranchGenerator(codegen), value_(value), scratch_(scratch) { }

  virtual void Emit(Label* label) const {
    __ Fabs(scratch_, value_);
    // Compare with 0.0. Because scratch_ is positive, the result can be one of
    // nZCv (equal), nzCv (greater) or nzCV (unordered).
    __ Fcmp(scratch_, 0.0);
    __ B(gt, label);
  }

  virtual void EmitInverted(Label* label) const {
    __ Fabs(scratch_, value_);
    __ Fcmp(scratch_, 0.0);
    __ B(le, label);
  }

 private:
  const FPRegister& value_;
  const FPRegister& scratch_;
};


// Test the input and branch if it is a heap number.
class BranchIfHeapNumber : public BranchGenerator {
 public:
  BranchIfHeapNumber(LCodeGen* codegen, const Register& value)
      : BranchGenerator(codegen), value_(value) { }

  virtual void Emit(Label* label) const {
    __ JumpIfHeapNumber(value_, label);
  }

  virtual void EmitInverted(Label* label) const {
    __ JumpIfNotHeapNumber(value_, label);
  }

 private:
  const Register& value_;
};


// Test the input and branch if it is the specified root value.
class BranchIfRoot : public BranchGenerator {
 public:
  BranchIfRoot(LCodeGen* codegen, const Register& value,
               Heap::RootListIndex index)
      : BranchGenerator(codegen), value_(value), index_(index) { }

  virtual void Emit(Label* label) const {
    __ JumpIfRoot(value_, index_, label);
  }

  virtual void EmitInverted(Label* label) const {
    __ JumpIfNotRoot(value_, index_, label);
  }

 private:
  const Register& value_;
  const Heap::RootListIndex index_;
};


void LCodeGen::WriteTranslation(LEnvironment* environment,
                                Translation* translation) {
  if (environment == NULL) return;

  // The translation includes one command per value in the environment.
  int translation_size = environment->translation_size();

  WriteTranslation(environment->outer(), translation);
  WriteTranslationFrame(environment, translation);

  int object_index = 0;
  int dematerialized_index = 0;
  for (int i = 0; i < translation_size; ++i) {
    LOperand* value = environment->values()->at(i);
    AddToTranslation(
        environment, translation, value, environment->HasTaggedValueAt(i),
        environment->HasUint32ValueAt(i), &object_index, &dematerialized_index);
  }
}


void LCodeGen::AddToTranslation(LEnvironment* environment,
                                Translation* translation,
                                LOperand* op,
                                bool is_tagged,
                                bool is_uint32,
                                int* object_index_pointer,
                                int* dematerialized_index_pointer) {
  if (op == LEnvironment::materialization_marker()) {
    int object_index = (*object_index_pointer)++;
    if (environment->ObjectIsDuplicateAt(object_index)) {
      int dupe_of = environment->ObjectDuplicateOfAt(object_index);
      translation->DuplicateObject(dupe_of);
      return;
    }
    int object_length = environment->ObjectLengthAt(object_index);
    if (environment->ObjectIsArgumentsAt(object_index)) {
      translation->BeginArgumentsObject(object_length);
    } else {
      translation->BeginCapturedObject(object_length);
    }
    int dematerialized_index = *dematerialized_index_pointer;
    int env_offset = environment->translation_size() + dematerialized_index;
    *dematerialized_index_pointer += object_length;
    for (int i = 0; i < object_length; ++i) {
      LOperand* value = environment->values()->at(env_offset + i);
      AddToTranslation(environment,
                       translation,
                       value,
                       environment->HasTaggedValueAt(env_offset + i),
                       environment->HasUint32ValueAt(env_offset + i),
                       object_index_pointer,
                       dematerialized_index_pointer);
    }
    return;
  }

  if (op->IsStackSlot()) {
    int index = op->index();
    if (is_tagged) {
      translation->StoreStackSlot(index);
    } else if (is_uint32) {
      translation->StoreUint32StackSlot(index);
    } else {
      translation->StoreInt32StackSlot(index);
    }
  } else if (op->IsDoubleStackSlot()) {
    int index = op->index();
    translation->StoreDoubleStackSlot(index);
  } else if (op->IsRegister()) {
    Register reg = ToRegister(op);
    if (is_tagged) {
      translation->StoreRegister(reg);
    } else if (is_uint32) {
      translation->StoreUint32Register(reg);
    } else {
      translation->StoreInt32Register(reg);
    }
  } else if (op->IsDoubleRegister()) {
    DoubleRegister reg = ToDoubleRegister(op);
    translation->StoreDoubleRegister(reg);
  } else if (op->IsConstantOperand()) {
    HConstant* constant = chunk()->LookupConstant(LConstantOperand::cast(op));
    int src_index = DefineDeoptimizationLiteral(constant->handle(isolate()));
    translation->StoreLiteral(src_index);
  } else {
    UNREACHABLE();
  }
}


void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                                    Safepoint::DeoptMode mode) {
  environment->set_has_been_used();
  if (!environment->HasBeenRegistered()) {
    int frame_count = 0;
    int jsframe_count = 0;
    for (LEnvironment* e = environment; e != NULL; e = e->outer()) {
      ++frame_count;
      if (e->frame_type() == JS_FUNCTION) {
        ++jsframe_count;
      }
    }
    Translation translation(&translations_, frame_count, jsframe_count, zone());
    WriteTranslation(environment, &translation);
    int deoptimization_index = deoptimizations_.length();
    int pc_offset = masm()->pc_offset();
    environment->Register(deoptimization_index,
                          translation.index(),
                          (mode == Safepoint::kLazyDeopt) ? pc_offset : -1);
    deoptimizations_.Add(environment, zone());
  }
}


void LCodeGen::CallCode(Handle<Code> code,
                        RelocInfo::Mode mode,
                        LInstruction* instr) {
  CallCodeGeneric(code, mode, instr, RECORD_SIMPLE_SAFEPOINT);
}


void LCodeGen::CallCodeGeneric(Handle<Code> code,
                               RelocInfo::Mode mode,
                               LInstruction* instr,
                               SafepointMode safepoint_mode) {
  DCHECK(instr != NULL);

  Assembler::BlockPoolsScope scope(masm_);
  __ Call(code, mode);
  RecordSafepointWithLazyDeopt(instr, safepoint_mode);

  if ((code->kind() == Code::BINARY_OP_IC) ||
      (code->kind() == Code::COMPARE_IC)) {
    // Signal that we don't inline smi code before these stubs in the
    // optimizing code generator.
    InlineSmiCheckInfo::EmitNotInlined(masm());
  }
}


void LCodeGen::DoCallNewArray(LCallNewArray* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->constructor()).is(x1));

  __ Mov(x0, Operand(instr->arity()));
  __ Mov(x2, instr->hydrogen()->site());

  ElementsKind kind = instr->hydrogen()->elements_kind();
  AllocationSiteOverrideMode override_mode =
      (AllocationSite::GetMode(kind) == TRACK_ALLOCATION_SITE)
          ? DISABLE_ALLOCATION_SITES
          : DONT_OVERRIDE;

  if (instr->arity() == 0) {
    ArrayNoArgumentConstructorStub stub(isolate(), kind, override_mode);
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  } else if (instr->arity() == 1) {
    Label done;
    if (IsFastPackedElementsKind(kind)) {
      Label packed_case;

      // We might need to create a holey array; look at the first argument.
      __ Peek(x10, 0);
      __ Cbz(x10, &packed_case);

      ElementsKind holey_kind = GetHoleyElementsKind(kind);
      ArraySingleArgumentConstructorStub stub(isolate(),
                                              holey_kind,
                                              override_mode);
      CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
      __ B(&done);
      __ Bind(&packed_case);
    }

    ArraySingleArgumentConstructorStub stub(isolate(), kind, override_mode);
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
    __ Bind(&done);
  } else {
    ArrayNArgumentsConstructorStub stub(isolate());
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  }
  RecordPushedArgumentsDelta(instr->hydrogen()->argument_delta());

  DCHECK(ToRegister(instr->result()).is(x0));
}


void LCodeGen::CallRuntime(const Runtime::Function* function,
                           int num_arguments,
                           LInstruction* instr,
                           SaveFPRegsMode save_doubles) {
  DCHECK(instr != NULL);

  __ CallRuntime(function, num_arguments, save_doubles);

  RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
}


void LCodeGen::LoadContextFromDeferred(LOperand* context) {
  if (context->IsRegister()) {
    __ Mov(cp, ToRegister(context));
  } else if (context->IsStackSlot()) {
    __ Ldr(cp, ToMemOperand(context, kMustUseFramePointer));
  } else if (context->IsConstantOperand()) {
    HConstant* constant =
        chunk_->LookupConstant(LConstantOperand::cast(context));
    __ LoadHeapObject(cp,
                      Handle<HeapObject>::cast(constant->handle(isolate())));
  } else {
    UNREACHABLE();
  }
}


void LCodeGen::CallRuntimeFromDeferred(Runtime::FunctionId id,
                                       int argc,
                                       LInstruction* instr,
                                       LOperand* context) {
  LoadContextFromDeferred(context);
  __ CallRuntimeSaveDoubles(id);
  RecordSafepointWithRegisters(
      instr->pointer_map(), argc, Safepoint::kNoLazyDeopt);
}


void LCodeGen::RecordAndWritePosition(int position) {
  if (position == RelocInfo::kNoPosition) return;
  masm()->positions_recorder()->RecordPosition(position);
}


void LCodeGen::RecordSafepointWithLazyDeopt(LInstruction* instr,
                                            SafepointMode safepoint_mode) {
  if (safepoint_mode == RECORD_SIMPLE_SAFEPOINT) {
    RecordSafepoint(instr->pointer_map(), Safepoint::kLazyDeopt);
  } else {
    DCHECK(safepoint_mode == RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
    RecordSafepointWithRegisters(
        instr->pointer_map(), 0, Safepoint::kLazyDeopt);
  }
}


void LCodeGen::RecordSafepoint(LPointerMap* pointers,
                               Safepoint::Kind kind,
                               int arguments,
                               Safepoint::DeoptMode deopt_mode) {
  DCHECK(expected_safepoint_kind_ == kind);

  const ZoneList<LOperand*>* operands = pointers->GetNormalizedOperands();
  Safepoint safepoint = safepoints_.DefineSafepoint(
      masm(), kind, arguments, deopt_mode);

  for (int i = 0; i < operands->length(); i++) {
    LOperand* pointer = operands->at(i);
    if (pointer->IsStackSlot()) {
      safepoint.DefinePointerSlot(pointer->index(), zone());
    } else if (pointer->IsRegister() && (kind & Safepoint::kWithRegisters)) {
      safepoint.DefinePointerRegister(ToRegister(pointer), zone());
    }
  }
}

void LCodeGen::RecordSafepoint(LPointerMap* pointers,
                               Safepoint::DeoptMode deopt_mode) {
  RecordSafepoint(pointers, Safepoint::kSimple, 0, deopt_mode);
}


void LCodeGen::RecordSafepoint(Safepoint::DeoptMode deopt_mode) {
  LPointerMap empty_pointers(zone());
  RecordSafepoint(&empty_pointers, deopt_mode);
}


void LCodeGen::RecordSafepointWithRegisters(LPointerMap* pointers,
                                            int arguments,
                                            Safepoint::DeoptMode deopt_mode) {
  RecordSafepoint(pointers, Safepoint::kWithRegisters, arguments, deopt_mode);
}


bool LCodeGen::GenerateCode() {
  LPhase phase("Z_Code generation", chunk());
  DCHECK(is_unused());
  status_ = GENERATING;

  // Open a frame scope to indicate that there is a frame on the stack.  The
  // NONE indicates that the scope shouldn't actually generate code to set up
  // the frame (that is done in GeneratePrologue).
  FrameScope frame_scope(masm_, StackFrame::NONE);

  return GeneratePrologue() && GenerateBody() && GenerateDeferredCode() &&
         GenerateJumpTable() && GenerateSafepointTable();
}


void LCodeGen::SaveCallerDoubles() {
  DCHECK(info()->saves_caller_doubles());
  DCHECK(NeedsEagerFrame());
  Comment(";;; Save clobbered callee double registers");
  BitVector* doubles = chunk()->allocated_double_registers();
  BitVector::Iterator iterator(doubles);
  int count = 0;
  while (!iterator.Done()) {
    // TODO(all): Is this supposed to save just the callee-saved doubles? It
    // looks like it's saving all of them.
    FPRegister value = FPRegister::from_code(iterator.Current());
    __ Poke(value, count * kDoubleSize);
    iterator.Advance();
    count++;
  }
}


void LCodeGen::RestoreCallerDoubles() {
  DCHECK(info()->saves_caller_doubles());
  DCHECK(NeedsEagerFrame());
  Comment(";;; Restore clobbered callee double registers");
  BitVector* doubles = chunk()->allocated_double_registers();
  BitVector::Iterator iterator(doubles);
  int count = 0;
  while (!iterator.Done()) {
    // TODO(all): Is this supposed to restore just the callee-saved doubles? It
    // looks like it's restoring all of them.
    FPRegister value = FPRegister::from_code(iterator.Current());
    __ Peek(value, count * kDoubleSize);
    iterator.Advance();
    count++;
  }
}


bool LCodeGen::GeneratePrologue() {
  DCHECK(is_generating());

  if (info()->IsOptimizing()) {
    ProfileEntryHookStub::MaybeCallEntryHook(masm_);
  }

  DCHECK(__ StackPointer().Is(jssp));
  info()->set_prologue_offset(masm_->pc_offset());
  if (NeedsEagerFrame()) {
    if (info()->IsStub()) {
      __ StubPrologue(
          StackFrame::STUB,
          GetStackSlotCount() + TypedFrameConstants::kFixedSlotCount);
    } else {
      __ Prologue(info()->GeneratePreagedPrologue());
      // Reserve space for the stack slots needed by the code.
      int slots = GetStackSlotCount();
      if (slots > 0) {
        __ Claim(slots, kPointerSize);
      }
    }
    frame_is_built_ = true;
  }

  if (info()->saves_caller_doubles()) {
    SaveCallerDoubles();
  }
  return !is_aborted();
}


void LCodeGen::DoPrologue(LPrologue* instr) {
  Comment(";;; Prologue begin");

  // Allocate a local context if needed.
  if (info()->scope()->num_heap_slots() > 0) {
    Comment(";;; Allocate local context");
    bool need_write_barrier = true;
    // Argument to NewContext is the function, which is in x1.
    int slots = info()->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
    Safepoint::DeoptMode deopt_mode = Safepoint::kNoLazyDeopt;
    if (info()->scope()->is_script_scope()) {
      __ Mov(x10, Operand(info()->scope()->GetScopeInfo(info()->isolate())));
      __ Push(x1, x10);
      __ CallRuntime(Runtime::kNewScriptContext);
      deopt_mode = Safepoint::kLazyDeopt;
    } else if (slots <= FastNewContextStub::kMaximumSlots) {
      FastNewContextStub stub(isolate(), slots);
      __ CallStub(&stub);
      // Result of FastNewContextStub is always in new space.
      need_write_barrier = false;
    } else {
      __ Push(x1);
      __ CallRuntime(Runtime::kNewFunctionContext);
    }
    RecordSafepoint(deopt_mode);
    // Context is returned in x0. It replaces the context passed to us. It's
    // saved in the stack and kept live in cp.
    __ Mov(cp, x0);
    __ Str(x0, MemOperand(fp, StandardFrameConstants::kContextOffset));
    // Copy any necessary parameters into the context.
    int num_parameters = scope()->num_parameters();
    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
    for (int i = first_parameter; i < num_parameters; i++) {
      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
      if (var->IsContextSlot()) {
        Register value = x0;
        Register scratch = x3;

        int parameter_offset = StandardFrameConstants::kCallerSPOffset +
            (num_parameters - 1 - i) * kPointerSize;
        // Load parameter from stack.
        __ Ldr(value, MemOperand(fp, parameter_offset));
        // Store it in the context.
        MemOperand target = ContextMemOperand(cp, var->index());
        __ Str(value, target);
        // Update the write barrier. This clobbers value and scratch.
        if (need_write_barrier) {
          __ RecordWriteContextSlot(cp, static_cast<int>(target.offset()),
                                    value, scratch, GetLinkRegisterState(),
                                    kSaveFPRegs);
        } else if (FLAG_debug_code) {
          Label done;
          __ JumpIfInNewSpace(cp, &done);
          __ Abort(kExpectedNewSpaceObject);
          __ bind(&done);
        }
      }
    }
    Comment(";;; End allocate local context");
  }

  Comment(";;; Prologue end");
}


void LCodeGen::GenerateOsrPrologue() {
  // Generate the OSR entry prologue at the first unknown OSR value, or if there
  // are none, at the OSR entrypoint instruction.
  if (osr_pc_offset_ >= 0) return;

  osr_pc_offset_ = masm()->pc_offset();

  // Adjust the frame size, subsuming the unoptimized frame into the
  // optimized frame.
  int slots = GetStackSlotCount() - graph()->osr()->UnoptimizedFrameSlots();
  DCHECK(slots >= 0);
  __ Claim(slots);
}


void LCodeGen::GenerateBodyInstructionPre(LInstruction* instr) {
  if (instr->IsCall()) {
    EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
  }
  if (!instr->IsLazyBailout() && !instr->IsGap()) {
    safepoints_.BumpLastLazySafepointIndex();
  }
}


bool LCodeGen::GenerateDeferredCode() {
  DCHECK(is_generating());
  if (deferred_.length() > 0) {
    for (int i = 0; !is_aborted() && (i < deferred_.length()); i++) {
      LDeferredCode* code = deferred_[i];

      HValue* value =
          instructions_->at(code->instruction_index())->hydrogen_value();
      RecordAndWritePosition(
          chunk()->graph()->SourcePositionToScriptPosition(value->position()));

      Comment(";;; <@%d,#%d> "
              "-------------------- Deferred %s --------------------",
              code->instruction_index(),
              code->instr()->hydrogen_value()->id(),
              code->instr()->Mnemonic());

      __ Bind(code->entry());

      if (NeedsDeferredFrame()) {
        Comment(";;; Build frame");
        DCHECK(!frame_is_built_);
        DCHECK(info()->IsStub());
        frame_is_built_ = true;
        __ Push(lr, fp);
        __ Mov(fp, Smi::FromInt(StackFrame::STUB));
        __ Push(fp);
        __ Add(fp, __ StackPointer(),
               TypedFrameConstants::kFixedFrameSizeFromFp);
        Comment(";;; Deferred code");
      }

      code->Generate();

      if (NeedsDeferredFrame()) {
        Comment(";;; Destroy frame");
        DCHECK(frame_is_built_);
        __ Pop(xzr, fp, lr);
        frame_is_built_ = false;
      }

      __ B(code->exit());
    }
  }

  // Force constant pool emission at the end of the deferred code to make
  // sure that no constant pools are emitted after deferred code because
  // deferred code generation is the last step which generates code. The two
  // following steps will only output data used by crakshaft.
  masm()->CheckConstPool(true, false);

  return !is_aborted();
}


bool LCodeGen::GenerateJumpTable() {
  Label needs_frame, call_deopt_entry;

  if (jump_table_.length() > 0) {
    Comment(";;; -------------------- Jump table --------------------");
    Address base = jump_table_[0]->address;

    UseScratchRegisterScope temps(masm());
    Register entry_offset = temps.AcquireX();

    int length = jump_table_.length();
    for (int i = 0; i < length; i++) {
      Deoptimizer::JumpTableEntry* table_entry = jump_table_[i];
      __ Bind(&table_entry->label);

      Address entry = table_entry->address;
      DeoptComment(table_entry->deopt_info);

      // Second-level deopt table entries are contiguous and small, so instead
      // of loading the full, absolute address of each one, load the base
      // address and add an immediate offset.
      __ Mov(entry_offset, entry - base);

      if (table_entry->needs_frame) {
        DCHECK(!info()->saves_caller_doubles());
        Comment(";;; call deopt with frame");
        // Save lr before Bl, fp will be adjusted in the needs_frame code.
        __ Push(lr, fp);
        // Reuse the existing needs_frame code.
        __ Bl(&needs_frame);
      } else {
        // There is nothing special to do, so just continue to the second-level
        // table.
        __ Bl(&call_deopt_entry);
      }

      masm()->CheckConstPool(false, false);
    }

    if (needs_frame.is_linked()) {
      // This variant of deopt can only be used with stubs. Since we don't
      // have a function pointer to install in the stack frame that we're
      // building, install a special marker there instead.
      DCHECK(info()->IsStub());

      Comment(";;; needs_frame common code");
      UseScratchRegisterScope temps(masm());
      Register stub_marker = temps.AcquireX();
      __ Bind(&needs_frame);
      __ Mov(stub_marker, Smi::FromInt(StackFrame::STUB));
      __ Push(cp, stub_marker);
      __ Add(fp, __ StackPointer(), 2 * kPointerSize);
    }

    // Generate common code for calling the second-level deopt table.
    __ Bind(&call_deopt_entry);

    if (info()->saves_caller_doubles()) {
      DCHECK(info()->IsStub());
      RestoreCallerDoubles();
    }

    Register deopt_entry = temps.AcquireX();
    __ Mov(deopt_entry, Operand(reinterpret_cast<uint64_t>(base),
                                RelocInfo::RUNTIME_ENTRY));
    __ Add(deopt_entry, deopt_entry, entry_offset);
    __ Br(deopt_entry);
  }

  // Force constant pool emission at the end of the deopt jump table to make
  // sure that no constant pools are emitted after.
  masm()->CheckConstPool(true, false);

  // The deoptimization jump table is the last part of the instruction
  // sequence. Mark the generated code as done unless we bailed out.
  if (!is_aborted()) status_ = DONE;
  return !is_aborted();
}


bool LCodeGen::GenerateSafepointTable() {
  DCHECK(is_done());
  // We do not know how much data will be emitted for the safepoint table, so
  // force emission of the veneer pool.
  masm()->CheckVeneerPool(true, true);
  safepoints_.Emit(masm(), GetTotalFrameSlotCount());
  return !is_aborted();
}


void LCodeGen::FinishCode(Handle<Code> code) {
  DCHECK(is_done());
  code->set_stack_slots(GetTotalFrameSlotCount());
  code->set_safepoint_table_offset(safepoints_.GetCodeOffset());
  PopulateDeoptimizationData(code);
}


void LCodeGen::DeoptimizeBranch(
    LInstruction* instr, Deoptimizer::DeoptReason deopt_reason,
    BranchType branch_type, Register reg, int bit,
    Deoptimizer::BailoutType* override_bailout_type) {
  LEnvironment* environment = instr->environment();
  RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
  Deoptimizer::BailoutType bailout_type =
    info()->IsStub() ? Deoptimizer::LAZY : Deoptimizer::EAGER;

  if (override_bailout_type != NULL) {
    bailout_type = *override_bailout_type;
  }

  DCHECK(environment->HasBeenRegistered());
  int id = environment->deoptimization_index();
  Address entry =
      Deoptimizer::GetDeoptimizationEntry(isolate(), id, bailout_type);

  if (entry == NULL) {
    Abort(kBailoutWasNotPrepared);
  }

  if (FLAG_deopt_every_n_times != 0 && !info()->IsStub()) {
    Label not_zero;
    ExternalReference count = ExternalReference::stress_deopt_count(isolate());

    __ Push(x0, x1, x2);
    __ Mrs(x2, NZCV);
    __ Mov(x0, count);
    __ Ldr(w1, MemOperand(x0));
    __ Subs(x1, x1, 1);
    __ B(gt, &not_zero);
    __ Mov(w1, FLAG_deopt_every_n_times);
    __ Str(w1, MemOperand(x0));
    __ Pop(x2, x1, x0);
    DCHECK(frame_is_built_);
    __ Call(entry, RelocInfo::RUNTIME_ENTRY);
    __ Unreachable();

    __ Bind(&not_zero);
    __ Str(w1, MemOperand(x0));
    __ Msr(NZCV, x2);
    __ Pop(x2, x1, x0);
  }

  if (info()->ShouldTrapOnDeopt()) {
    Label dont_trap;
    __ B(&dont_trap, InvertBranchType(branch_type), reg, bit);
    __ Debug("trap_on_deopt", __LINE__, BREAK);
    __ Bind(&dont_trap);
  }

  Deoptimizer::DeoptInfo deopt_info = MakeDeoptInfo(instr, deopt_reason, id);

  DCHECK(info()->IsStub() || frame_is_built_);
  // Go through jump table if we need to build frame, or restore caller doubles.
  if (branch_type == always &&
      frame_is_built_ && !info()->saves_caller_doubles()) {
    DeoptComment(deopt_info);
    __ Call(entry, RelocInfo::RUNTIME_ENTRY);
  } else {
    Deoptimizer::JumpTableEntry* table_entry =
        new (zone()) Deoptimizer::JumpTableEntry(
            entry, deopt_info, bailout_type, !frame_is_built_);
    // We often have several deopts to the same entry, reuse the last
    // jump entry if this is the case.
    if (FLAG_trace_deopt || isolate()->is_profiling() ||
        jump_table_.is_empty() ||
        !table_entry->IsEquivalentTo(*jump_table_.last())) {
      jump_table_.Add(table_entry, zone());
    }
    __ B(&jump_table_.last()->label, branch_type, reg, bit);
  }
}


void LCodeGen::Deoptimize(LInstruction* instr,
                          Deoptimizer::DeoptReason deopt_reason,
                          Deoptimizer::BailoutType* override_bailout_type) {
  DeoptimizeBranch(instr, deopt_reason, always, NoReg, -1,
                   override_bailout_type);
}


void LCodeGen::DeoptimizeIf(Condition cond, LInstruction* instr,
                            Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeBranch(instr, deopt_reason, static_cast<BranchType>(cond));
}


void LCodeGen::DeoptimizeIfZero(Register rt, LInstruction* instr,
                                Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeBranch(instr, deopt_reason, reg_zero, rt);
}


void LCodeGen::DeoptimizeIfNotZero(Register rt, LInstruction* instr,
                                   Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeBranch(instr, deopt_reason, reg_not_zero, rt);
}


void LCodeGen::DeoptimizeIfNegative(Register rt, LInstruction* instr,
                                    Deoptimizer::DeoptReason deopt_reason) {
  int sign_bit = rt.Is64Bits() ? kXSignBit : kWSignBit;
  DeoptimizeIfBitSet(rt, sign_bit, instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfSmi(Register rt, LInstruction* instr,
                               Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeIfBitClear(rt, MaskToBit(kSmiTagMask), instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfNotSmi(Register rt, LInstruction* instr,
                                  Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeIfBitSet(rt, MaskToBit(kSmiTagMask), instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfRoot(Register rt, Heap::RootListIndex index,
                                LInstruction* instr,
                                Deoptimizer::DeoptReason deopt_reason) {
  __ CompareRoot(rt, index);
  DeoptimizeIf(eq, instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfNotRoot(Register rt, Heap::RootListIndex index,
                                   LInstruction* instr,
                                   Deoptimizer::DeoptReason deopt_reason) {
  __ CompareRoot(rt, index);
  DeoptimizeIf(ne, instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfMinusZero(DoubleRegister input, LInstruction* instr,
                                     Deoptimizer::DeoptReason deopt_reason) {
  __ TestForMinusZero(input);
  DeoptimizeIf(vs, instr, deopt_reason);
}


void LCodeGen::DeoptimizeIfNotHeapNumber(Register object, LInstruction* instr) {
  __ CompareObjectMap(object, Heap::kHeapNumberMapRootIndex);
  DeoptimizeIf(ne, instr, Deoptimizer::kNotAHeapNumber);
}


void LCodeGen::DeoptimizeIfBitSet(Register rt, int bit, LInstruction* instr,
                                  Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeBranch(instr, deopt_reason, reg_bit_set, rt, bit);
}


void LCodeGen::DeoptimizeIfBitClear(Register rt, int bit, LInstruction* instr,
                                    Deoptimizer::DeoptReason deopt_reason) {
  DeoptimizeBranch(instr, deopt_reason, reg_bit_clear, rt, bit);
}


void LCodeGen::EnsureSpaceForLazyDeopt(int space_needed) {
  if (info()->ShouldEnsureSpaceForLazyDeopt()) {
    // Ensure that we have enough space after the previous lazy-bailout
    // instruction for patching the code here.
    intptr_t current_pc = masm()->pc_offset();

    if (current_pc < (last_lazy_deopt_pc_ + space_needed)) {
      ptrdiff_t padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
      DCHECK((padding_size % kInstructionSize) == 0);
      InstructionAccurateScope instruction_accurate(
          masm(), padding_size / kInstructionSize);

      while (padding_size > 0) {
        __ nop();
        padding_size -= kInstructionSize;
      }
    }
  }
  last_lazy_deopt_pc_ = masm()->pc_offset();
}


Register LCodeGen::ToRegister(LOperand* op) const {
  // TODO(all): support zero register results, as ToRegister32.
  DCHECK((op != NULL) && op->IsRegister());
  return Register::from_code(op->index());
}


Register LCodeGen::ToRegister32(LOperand* op) const {
  DCHECK(op != NULL);
  if (op->IsConstantOperand()) {
    // If this is a constant operand, the result must be the zero register.
    DCHECK(ToInteger32(LConstantOperand::cast(op)) == 0);
    return wzr;
  } else {
    return ToRegister(op).W();
  }
}


Smi* LCodeGen::ToSmi(LConstantOperand* op) const {
  HConstant* constant = chunk_->LookupConstant(op);
  return Smi::FromInt(constant->Integer32Value());
}


DoubleRegister LCodeGen::ToDoubleRegister(LOperand* op) const {
  DCHECK((op != NULL) && op->IsDoubleRegister());
  return DoubleRegister::from_code(op->index());
}


Operand LCodeGen::ToOperand(LOperand* op) {
  DCHECK(op != NULL);
  if (op->IsConstantOperand()) {
    LConstantOperand* const_op = LConstantOperand::cast(op);
    HConstant* constant = chunk()->LookupConstant(const_op);
    Representation r = chunk_->LookupLiteralRepresentation(const_op);
    if (r.IsSmi()) {
      DCHECK(constant->HasSmiValue());
      return Operand(Smi::FromInt(constant->Integer32Value()));
    } else if (r.IsInteger32()) {
      DCHECK(constant->HasInteger32Value());
      return Operand(constant->Integer32Value());
    } else if (r.IsDouble()) {
      Abort(kToOperandUnsupportedDoubleImmediate);
    }
    DCHECK(r.IsTagged());
    return Operand(constant->handle(isolate()));
  } else if (op->IsRegister()) {
    return Operand(ToRegister(op));
  } else if (op->IsDoubleRegister()) {
    Abort(kToOperandIsDoubleRegisterUnimplemented);
    return Operand(0);
  }
  // Stack slots not implemented, use ToMemOperand instead.
  UNREACHABLE();
  return Operand(0);
}


Operand LCodeGen::ToOperand32(LOperand* op) {
  DCHECK(op != NULL);
  if (op->IsRegister()) {
    return Operand(ToRegister32(op));
  } else if (op->IsConstantOperand()) {
    LConstantOperand* const_op = LConstantOperand::cast(op);
    HConstant* constant = chunk()->LookupConstant(const_op);
    Representation r = chunk_->LookupLiteralRepresentation(const_op);
    if (r.IsInteger32()) {
      return Operand(constant->Integer32Value());
    } else {
      // Other constants not implemented.
      Abort(kToOperand32UnsupportedImmediate);
    }
  }
  // Other cases are not implemented.
  UNREACHABLE();
  return Operand(0);
}


static int64_t ArgumentsOffsetWithoutFrame(int index) {
  DCHECK(index < 0);
  return -(index + 1) * kPointerSize;
}


MemOperand LCodeGen::ToMemOperand(LOperand* op, StackMode stack_mode) const {
  DCHECK(op != NULL);
  DCHECK(!op->IsRegister());
  DCHECK(!op->IsDoubleRegister());
  DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
  if (NeedsEagerFrame()) {
    int fp_offset = FrameSlotToFPOffset(op->index());
    // Loads and stores have a bigger reach in positive offset than negative.
    // We try to access using jssp (positive offset) first, then fall back to
    // fp (negative offset) if that fails.
    //
    // We can reference a stack slot from jssp only if we know how much we've
    // put on the stack. We don't know this in the following cases:
    // - stack_mode != kCanUseStackPointer: this is the case when deferred
    //   code has saved the registers.
    // - saves_caller_doubles(): some double registers have been pushed, jssp
    //   references the end of the double registers and not the end of the stack
    //   slots.
    // In both of the cases above, we _could_ add the tracking information
    // required so that we can use jssp here, but in practice it isn't worth it.
    if ((stack_mode == kCanUseStackPointer) &&
        !info()->saves_caller_doubles()) {
      int jssp_offset_to_fp =
          (pushed_arguments_ + GetTotalFrameSlotCount()) * kPointerSize -
          StandardFrameConstants::kFixedFrameSizeAboveFp;
      int jssp_offset = fp_offset + jssp_offset_to_fp;
      if (masm()->IsImmLSScaled(jssp_offset, LSDoubleWord)) {
        return MemOperand(masm()->StackPointer(), jssp_offset);
      }
    }
    return MemOperand(fp, fp_offset);
  } else {
    // Retrieve parameter without eager stack-frame relative to the
    // stack-pointer.
    return MemOperand(masm()->StackPointer(),
                      ArgumentsOffsetWithoutFrame(op->index()));
  }
}


Handle<Object> LCodeGen::ToHandle(LConstantOperand* op) const {
  HConstant* constant = chunk_->LookupConstant(op);
  DCHECK(chunk_->LookupLiteralRepresentation(op).IsSmiOrTagged());
  return constant->handle(isolate());
}


template <class LI>
Operand LCodeGen::ToShiftedRightOperand32(LOperand* right, LI* shift_info) {
  if (shift_info->shift() == NO_SHIFT) {
    return ToOperand32(right);
  } else {
    return Operand(
        ToRegister32(right),
        shift_info->shift(),
        JSShiftAmountFromLConstant(shift_info->shift_amount()));
  }
}


bool LCodeGen::IsSmi(LConstantOperand* op) const {
  return chunk_->LookupLiteralRepresentation(op).IsSmi();
}


bool LCodeGen::IsInteger32Constant(LConstantOperand* op) const {
  return chunk_->LookupLiteralRepresentation(op).IsSmiOrInteger32();
}


int32_t LCodeGen::ToInteger32(LConstantOperand* op) const {
  HConstant* constant = chunk_->LookupConstant(op);
  return constant->Integer32Value();
}


double LCodeGen::ToDouble(LConstantOperand* op) const {
  HConstant* constant = chunk_->LookupConstant(op);
  DCHECK(constant->HasDoubleValue());
  return constant->DoubleValue();
}


Condition LCodeGen::TokenToCondition(Token::Value op, bool is_unsigned) {
  Condition cond = nv;
  switch (op) {
    case Token::EQ:
    case Token::EQ_STRICT:
      cond = eq;
      break;
    case Token::NE:
    case Token::NE_STRICT:
      cond = ne;
      break;
    case Token::LT:
      cond = is_unsigned ? lo : lt;
      break;
    case Token::GT:
      cond = is_unsigned ? hi : gt;
      break;
    case Token::LTE:
      cond = is_unsigned ? ls : le;
      break;
    case Token::GTE:
      cond = is_unsigned ? hs : ge;
      break;
    case Token::IN:
    case Token::INSTANCEOF:
    default:
      UNREACHABLE();
  }
  return cond;
}


template<class InstrType>
void LCodeGen::EmitBranchGeneric(InstrType instr,
                                 const BranchGenerator& branch) {
  int left_block = instr->TrueDestination(chunk_);
  int right_block = instr->FalseDestination(chunk_);

  int next_block = GetNextEmittedBlock();

  if (right_block == left_block) {
    EmitGoto(left_block);
  } else if (left_block == next_block) {
    branch.EmitInverted(chunk_->GetAssemblyLabel(right_block));
  } else {
    branch.Emit(chunk_->GetAssemblyLabel(left_block));
    if (right_block != next_block) {
      __ B(chunk_->GetAssemblyLabel(right_block));
    }
  }
}


template<class InstrType>
void LCodeGen::EmitBranch(InstrType instr, Condition condition) {
  DCHECK((condition != al) && (condition != nv));
  BranchOnCondition branch(this, condition);
  EmitBranchGeneric(instr, branch);
}


template<class InstrType>
void LCodeGen::EmitCompareAndBranch(InstrType instr,
                                    Condition condition,
                                    const Register& lhs,
                                    const Operand& rhs) {
  DCHECK((condition != al) && (condition != nv));
  CompareAndBranch branch(this, condition, lhs, rhs);
  EmitBranchGeneric(instr, branch);
}


template<class InstrType>
void LCodeGen::EmitTestAndBranch(InstrType instr,
                                 Condition condition,
                                 const Register& value,
                                 uint64_t mask) {
  DCHECK((condition != al) && (condition != nv));
  TestAndBranch branch(this, condition, value, mask);
  EmitBranchGeneric(instr, branch);
}


template<class InstrType>
void LCodeGen::EmitBranchIfNonZeroNumber(InstrType instr,
                                         const FPRegister& value,
                                         const FPRegister& scratch) {
  BranchIfNonZeroNumber branch(this, value, scratch);
  EmitBranchGeneric(instr, branch);
}


template<class InstrType>
void LCodeGen::EmitBranchIfHeapNumber(InstrType instr,
                                      const Register& value) {
  BranchIfHeapNumber branch(this, value);
  EmitBranchGeneric(instr, branch);
}


template<class InstrType>
void LCodeGen::EmitBranchIfRoot(InstrType instr,
                                const Register& value,
                                Heap::RootListIndex index) {
  BranchIfRoot branch(this, value, index);
  EmitBranchGeneric(instr, branch);
}


void LCodeGen::DoGap(LGap* gap) {
  for (int i = LGap::FIRST_INNER_POSITION;
       i <= LGap::LAST_INNER_POSITION;
       i++) {
    LGap::InnerPosition inner_pos = static_cast<LGap::InnerPosition>(i);
    LParallelMove* move = gap->GetParallelMove(inner_pos);
    if (move != NULL) {
      resolver_.Resolve(move);
    }
  }
}


void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
  Register arguments = ToRegister(instr->arguments());
  Register result = ToRegister(instr->result());

  // The pointer to the arguments array come from DoArgumentsElements.
  // It does not point directly to the arguments and there is an offest of
  // two words that we must take into account when accessing an argument.
  // Subtracting the index from length accounts for one, so we add one more.

  if (instr->length()->IsConstantOperand() &&
      instr->index()->IsConstantOperand()) {
    int index = ToInteger32(LConstantOperand::cast(instr->index()));
    int length = ToInteger32(LConstantOperand::cast(instr->length()));
    int offset = ((length - index) + 1) * kPointerSize;
    __ Ldr(result, MemOperand(arguments, offset));
  } else if (instr->index()->IsConstantOperand()) {
    Register length = ToRegister32(instr->length());
    int index = ToInteger32(LConstantOperand::cast(instr->index()));
    int loc = index - 1;
    if (loc != 0) {
      __ Sub(result.W(), length, loc);
      __ Ldr(result, MemOperand(arguments, result, UXTW, kPointerSizeLog2));
    } else {
      __ Ldr(result, MemOperand(arguments, length, UXTW, kPointerSizeLog2));
    }
  } else {
    Register length = ToRegister32(instr->length());
    Operand index = ToOperand32(instr->index());
    __ Sub(result.W(), length, index);
    __ Add(result.W(), result.W(), 1);
    __ Ldr(result, MemOperand(arguments, result, UXTW, kPointerSizeLog2));
  }
}


void LCodeGen::DoAddE(LAddE* instr) {
  Register result = ToRegister(instr->result());
  Register left = ToRegister(instr->left());
  Operand right = Operand(x0);  // Dummy initialization.
  if (instr->hydrogen()->external_add_type() == AddOfExternalAndTagged) {
    right = Operand(ToRegister(instr->right()));
  } else if (instr->right()->IsConstantOperand()) {
    right = ToInteger32(LConstantOperand::cast(instr->right()));
  } else {
    right = Operand(ToRegister32(instr->right()), SXTW);
  }

  DCHECK(!instr->hydrogen()->CheckFlag(HValue::kCanOverflow));
  __ Add(result, left, right);
}


void LCodeGen::DoAddI(LAddI* instr) {
  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  Register result = ToRegister32(instr->result());
  Register left = ToRegister32(instr->left());
  Operand right = ToShiftedRightOperand32(instr->right(), instr);

  if (can_overflow) {
    __ Adds(result, left, right);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  } else {
    __ Add(result, left, right);
  }
}


void LCodeGen::DoAddS(LAddS* instr) {
  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  Register result = ToRegister(instr->result());
  Register left = ToRegister(instr->left());
  Operand right = ToOperand(instr->right());
  if (can_overflow) {
    __ Adds(result, left, right);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  } else {
    __ Add(result, left, right);
  }
}


void LCodeGen::DoAllocate(LAllocate* instr) {
  class DeferredAllocate: public LDeferredCode {
   public:
    DeferredAllocate(LCodeGen* codegen, LAllocate* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() { codegen()->DoDeferredAllocate(instr_); }
    virtual LInstruction* instr() { return instr_; }
   private:
    LAllocate* instr_;
  };

  DeferredAllocate* deferred = new(zone()) DeferredAllocate(this, instr);

  Register result = ToRegister(instr->result());
  Register temp1 = ToRegister(instr->temp1());
  Register temp2 = ToRegister(instr->temp2());

  // Allocate memory for the object.
  AllocationFlags flags = NO_ALLOCATION_FLAGS;
  if (instr->hydrogen()->MustAllocateDoubleAligned()) {
    flags = static_cast<AllocationFlags>(flags | DOUBLE_ALIGNMENT);
  }

  if (instr->hydrogen()->IsOldSpaceAllocation()) {
    DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
    flags = static_cast<AllocationFlags>(flags | PRETENURE);
  }

  if (instr->hydrogen()->IsAllocationFoldingDominator()) {
    flags = static_cast<AllocationFlags>(flags | ALLOCATION_FOLDING_DOMINATOR);
  }
  DCHECK(!instr->hydrogen()->IsAllocationFolded());

  if (instr->size()->IsConstantOperand()) {
    int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
    CHECK(size <= Page::kMaxRegularHeapObjectSize);
    __ Allocate(size, result, temp1, temp2, deferred->entry(), flags);
  } else {
    Register size = ToRegister32(instr->size());
    __ Sxtw(size.X(), size);
    __ Allocate(size.X(), result, temp1, temp2, deferred->entry(), flags);
  }

  __ Bind(deferred->exit());

  if (instr->hydrogen()->MustPrefillWithFiller()) {
    Register start = temp1;
    Register end = temp2;
    Register filler = ToRegister(instr->temp3());

    __ Sub(start, result, kHeapObjectTag);

    if (instr->size()->IsConstantOperand()) {
      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
      __ Add(end, start, size);
    } else {
      __ Add(end, start, ToRegister(instr->size()));
    }
    __ LoadRoot(filler, Heap::kOnePointerFillerMapRootIndex);
    __ InitializeFieldsWithFiller(start, end, filler);
  } else {
    DCHECK(instr->temp3() == NULL);
  }
}


void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
  // TODO(3095996): Get rid of this. For now, we need to make the
  // result register contain a valid pointer because it is already
  // contained in the register pointer map.
  __ Mov(ToRegister(instr->result()), Smi::FromInt(0));

  PushSafepointRegistersScope scope(this);
  // We're in a SafepointRegistersScope so we can use any scratch registers.
  Register size = x0;
  if (instr->size()->IsConstantOperand()) {
    __ Mov(size, ToSmi(LConstantOperand::cast(instr->size())));
  } else {
    __ SmiTag(size, ToRegister32(instr->size()).X());
  }
  int flags = AllocateDoubleAlignFlag::encode(
      instr->hydrogen()->MustAllocateDoubleAligned());
  if (instr->hydrogen()->IsOldSpaceAllocation()) {
    DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
    flags = AllocateTargetSpace::update(flags, OLD_SPACE);
  } else {
    flags = AllocateTargetSpace::update(flags, NEW_SPACE);
  }
  __ Mov(x10, Smi::FromInt(flags));
  __ Push(size, x10);

  CallRuntimeFromDeferred(
      Runtime::kAllocateInTargetSpace, 2, instr, instr->context());
  __ StoreToSafepointRegisterSlot(x0, ToRegister(instr->result()));

  if (instr->hydrogen()->IsAllocationFoldingDominator()) {
    AllocationFlags allocation_flags = NO_ALLOCATION_FLAGS;
    if (instr->hydrogen()->IsOldSpaceAllocation()) {
      DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
      allocation_flags = static_cast<AllocationFlags>(flags | PRETENURE);
    }
    // If the allocation folding dominator allocate triggered a GC, allocation
    // happend in the runtime. We have to reset the top pointer to virtually
    // undo the allocation.
    ExternalReference allocation_top =
        AllocationUtils::GetAllocationTopReference(isolate(), allocation_flags);
    Register top_address = x10;
    __ Sub(x0, x0, Operand(kHeapObjectTag));
    __ Mov(top_address, Operand(allocation_top));
    __ Str(x0, MemOperand(top_address));
    __ Add(x0, x0, Operand(kHeapObjectTag));
  }
}

void LCodeGen::DoFastAllocate(LFastAllocate* instr) {
  DCHECK(instr->hydrogen()->IsAllocationFolded());
  DCHECK(!instr->hydrogen()->IsAllocationFoldingDominator());
  Register result = ToRegister(instr->result());
  Register scratch1 = ToRegister(instr->temp1());
  Register scratch2 = ToRegister(instr->temp2());

  AllocationFlags flags = ALLOCATION_FOLDED;
  if (instr->hydrogen()->MustAllocateDoubleAligned()) {
    flags = static_cast<AllocationFlags>(flags | DOUBLE_ALIGNMENT);
  }
  if (instr->hydrogen()->IsOldSpaceAllocation()) {
    DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
    flags = static_cast<AllocationFlags>(flags | PRETENURE);
  }
  if (instr->size()->IsConstantOperand()) {
    int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
    CHECK(size <= Page::kMaxRegularHeapObjectSize);
    __ FastAllocate(size, result, scratch1, scratch2, flags);
  } else {
    Register size = ToRegister(instr->size());
    __ FastAllocate(size, result, scratch1, scratch2, flags);
  }
}


void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
  Register receiver = ToRegister(instr->receiver());
  Register function = ToRegister(instr->function());
  Register length = ToRegister32(instr->length());

  Register elements = ToRegister(instr->elements());
  Register scratch = x5;
  DCHECK(receiver.Is(x0));  // Used for parameter count.
  DCHECK(function.Is(x1));  // Required by InvokeFunction.
  DCHECK(ToRegister(instr->result()).Is(x0));
  DCHECK(instr->IsMarkedAsCall());

  // Copy the arguments to this function possibly from the
  // adaptor frame below it.
  const uint32_t kArgumentsLimit = 1 * KB;
  __ Cmp(length, kArgumentsLimit);
  DeoptimizeIf(hi, instr, Deoptimizer::kTooManyArguments);

  // Push the receiver and use the register to keep the original
  // number of arguments.
  __ Push(receiver);
  Register argc = receiver;
  receiver = NoReg;
  __ Sxtw(argc, length);
  // The arguments are at a one pointer size offset from elements.
  __ Add(elements, elements, 1 * kPointerSize);

  // Loop through the arguments pushing them onto the execution
  // stack.
  Label invoke, loop;
  // length is a small non-negative integer, due to the test above.
  __ Cbz(length, &invoke);
  __ Bind(&loop);
  __ Ldr(scratch, MemOperand(elements, length, SXTW, kPointerSizeLog2));
  __ Push(scratch);
  __ Subs(length, length, 1);
  __ B(ne, &loop);

  __ Bind(&invoke);

  InvokeFlag flag = CALL_FUNCTION;
  if (instr->hydrogen()->tail_call_mode() == TailCallMode::kAllow) {
    DCHECK(!info()->saves_caller_doubles());
    // TODO(ishell): drop current frame before pushing arguments to the stack.
    flag = JUMP_FUNCTION;
    ParameterCount actual(x0);
    // It is safe to use x3, x4 and x5 as scratch registers here given that
    // 1) we are not going to return to caller function anyway,
    // 2) x3 (new.target) will be initialized below.
    PrepareForTailCall(actual, x3, x4, x5);
  }

  DCHECK(instr->HasPointerMap());
  LPointerMap* pointers = instr->pointer_map();
  SafepointGenerator safepoint_generator(this, pointers, Safepoint::kLazyDeopt);
  // The number of arguments is stored in argc (receiver) which is x0, as
  // expected by InvokeFunction.
  ParameterCount actual(argc);
  __ InvokeFunction(function, no_reg, actual, flag, safepoint_generator);
}


void LCodeGen::DoArgumentsElements(LArgumentsElements* instr) {
  Register result = ToRegister(instr->result());

  if (instr->hydrogen()->from_inlined()) {
    // When we are inside an inlined function, the arguments are the last things
    // that have been pushed on the stack. Therefore the arguments array can be
    // accessed directly from jssp.
    // However in the normal case, it is accessed via fp but there are two words
    // on the stack between fp and the arguments (the saved lr and fp) and the
    // LAccessArgumentsAt implementation take that into account.
    // In the inlined case we need to subtract the size of 2 words to jssp to
    // get a pointer which will work well with LAccessArgumentsAt.
    DCHECK(masm()->StackPointer().Is(jssp));
    __ Sub(result, jssp, 2 * kPointerSize);
  } else if (instr->hydrogen()->arguments_adaptor()) {
    DCHECK(instr->temp() != NULL);
    Register previous_fp = ToRegister(instr->temp());

    __ Ldr(previous_fp,
           MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
    __ Ldr(result, MemOperand(previous_fp,
                              CommonFrameConstants::kContextOrFrameTypeOffset));
    __ Cmp(result, Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR));
    __ Csel(result, fp, previous_fp, ne);
  } else {
    __ Mov(result, fp);
  }
}


void LCodeGen::DoArgumentsLength(LArgumentsLength* instr) {
  Register elements = ToRegister(instr->elements());
  Register result = ToRegister32(instr->result());
  Label done;

  // If no arguments adaptor frame the number of arguments is fixed.
  __ Cmp(fp, elements);
  __ Mov(result, scope()->num_parameters());
  __ B(eq, &done);

  // Arguments adaptor frame present. Get argument length from there.
  __ Ldr(result.X(), MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ Ldr(result,
         UntagSmiMemOperand(result.X(),
                            ArgumentsAdaptorFrameConstants::kLengthOffset));

  // Argument length is in result register.
  __ Bind(&done);
}


void LCodeGen::DoArithmeticD(LArithmeticD* instr) {
  DoubleRegister left = ToDoubleRegister(instr->left());
  DoubleRegister right = ToDoubleRegister(instr->right());
  DoubleRegister result = ToDoubleRegister(instr->result());

  switch (instr->op()) {
    case Token::ADD: __ Fadd(result, left, right); break;
    case Token::SUB: __ Fsub(result, left, right); break;
    case Token::MUL: __ Fmul(result, left, right); break;
    case Token::DIV: __ Fdiv(result, left, right); break;
    case Token::MOD: {
      // The ECMA-262 remainder operator is the remainder from a truncating
      // (round-towards-zero) division. Note that this differs from IEEE-754.
      //
      // TODO(jbramley): See if it's possible to do this inline, rather than by
      // calling a helper function. With frintz (to produce the intermediate
      // quotient) and fmsub (to calculate the remainder without loss of
      // precision), it should be possible. However, we would need support for
      // fdiv in round-towards-zero mode, and the ARM64 simulator doesn't
      // support that yet.
      DCHECK(left.Is(d0));
      DCHECK(right.Is(d1));
      __ CallCFunction(
          ExternalReference::mod_two_doubles_operation(isolate()),
          0, 2);
      DCHECK(result.Is(d0));
      break;
    }
    default:
      UNREACHABLE();
      break;
  }
}


void LCodeGen::DoArithmeticT(LArithmeticT* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->left()).is(x1));
  DCHECK(ToRegister(instr->right()).is(x0));
  DCHECK(ToRegister(instr->result()).is(x0));

  Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), instr->op()).code();
  CallCode(code, RelocInfo::CODE_TARGET, instr);
}


void LCodeGen::DoBitI(LBitI* instr) {
  Register result = ToRegister32(instr->result());
  Register left = ToRegister32(instr->left());
  Operand right = ToShiftedRightOperand32(instr->right(), instr);

  switch (instr->op()) {
    case Token::BIT_AND: __ And(result, left, right); break;
    case Token::BIT_OR:  __ Orr(result, left, right); break;
    case Token::BIT_XOR: __ Eor(result, left, right); break;
    default:
      UNREACHABLE();
      break;
  }
}


void LCodeGen::DoBitS(LBitS* instr) {
  Register result = ToRegister(instr->result());
  Register left = ToRegister(instr->left());
  Operand right = ToOperand(instr->right());

  switch (instr->op()) {
    case Token::BIT_AND: __ And(result, left, right); break;
    case Token::BIT_OR:  __ Orr(result, left, right); break;
    case Token::BIT_XOR: __ Eor(result, left, right); break;
    default:
      UNREACHABLE();
      break;
  }
}


void LCodeGen::DoBoundsCheck(LBoundsCheck *instr) {
  Condition cond = instr->hydrogen()->allow_equality() ? hi : hs;
  DCHECK(instr->hydrogen()->index()->representation().IsInteger32());
  DCHECK(instr->hydrogen()->length()->representation().IsInteger32());
  if (instr->index()->IsConstantOperand()) {
    Operand index = ToOperand32(instr->index());
    Register length = ToRegister32(instr->length());
    __ Cmp(length, index);
    cond = CommuteCondition(cond);
  } else {
    Register index = ToRegister32(instr->index());
    Operand length = ToOperand32(instr->length());
    __ Cmp(index, length);
  }
  if (FLAG_debug_code && instr->hydrogen()->skip_check()) {
    __ Assert(NegateCondition(cond), kEliminatedBoundsCheckFailed);
  } else {
    DeoptimizeIf(cond, instr, Deoptimizer::kOutOfBounds);
  }
}


void LCodeGen::DoBranch(LBranch* instr) {
  Representation r = instr->hydrogen()->value()->representation();
  Label* true_label = instr->TrueLabel(chunk_);
  Label* false_label = instr->FalseLabel(chunk_);

  if (r.IsInteger32()) {
    DCHECK(!info()->IsStub());
    EmitCompareAndBranch(instr, ne, ToRegister32(instr->value()), 0);
  } else if (r.IsSmi()) {
    DCHECK(!info()->IsStub());
    STATIC_ASSERT(kSmiTag == 0);
    EmitCompareAndBranch(instr, ne, ToRegister(instr->value()), 0);
  } else if (r.IsDouble()) {
    DoubleRegister value = ToDoubleRegister(instr->value());
    // Test the double value. Zero and NaN are false.
    EmitBranchIfNonZeroNumber(instr, value, double_scratch());
  } else {
    DCHECK(r.IsTagged());
    Register value = ToRegister(instr->value());
    HType type = instr->hydrogen()->value()->type();

    if (type.IsBoolean()) {
      DCHECK(!info()->IsStub());
      __ CompareRoot(value, Heap::kTrueValueRootIndex);
      EmitBranch(instr, eq);
    } else if (type.IsSmi()) {
      DCHECK(!info()->IsStub());
      EmitCompareAndBranch(instr, ne, value, Smi::FromInt(0));
    } else if (type.IsJSArray()) {
      DCHECK(!info()->IsStub());
      EmitGoto(instr->TrueDestination(chunk()));
    } else if (type.IsHeapNumber()) {
      DCHECK(!info()->IsStub());
      __ Ldr(double_scratch(), FieldMemOperand(value,
                                               HeapNumber::kValueOffset));
      // Test the double value. Zero and NaN are false.
      EmitBranchIfNonZeroNumber(instr, double_scratch(), double_scratch());
    } else if (type.IsString()) {
      DCHECK(!info()->IsStub());
      Register temp = ToRegister(instr->temp1());
      __ Ldr(temp, FieldMemOperand(value, String::kLengthOffset));
      EmitCompareAndBranch(instr, ne, temp, 0);
    } else {
      ToBooleanICStub::Types expected =
          instr->hydrogen()->expected_input_types();
      // Avoid deopts in the case where we've never executed this path before.
      if (expected.IsEmpty()) expected = ToBooleanICStub::Types::Generic();

      if (expected.Contains(ToBooleanICStub::UNDEFINED)) {
        // undefined -> false.
        __ JumpIfRoot(
            value, Heap::kUndefinedValueRootIndex, false_label);
      }

      if (expected.Contains(ToBooleanICStub::BOOLEAN)) {
        // Boolean -> its value.
        __ JumpIfRoot(
            value, Heap::kTrueValueRootIndex, true_label);
        __ JumpIfRoot(
            value, Heap::kFalseValueRootIndex, false_label);
      }

      if (expected.Contains(ToBooleanICStub::NULL_TYPE)) {
        // 'null' -> false.
        __ JumpIfRoot(
            value, Heap::kNullValueRootIndex, false_label);
      }

      if (expected.Contains(ToBooleanICStub::SMI)) {
        // Smis: 0 -> false, all other -> true.
        DCHECK(Smi::FromInt(0) == 0);
        __ Cbz(value, false_label);
        __ JumpIfSmi(value, true_label);
      } else if (expected.NeedsMap()) {
        // If we need a map later and have a smi, deopt.
        DeoptimizeIfSmi(value, instr, Deoptimizer::kSmi);
      }

      Register map = NoReg;
      Register scratch = NoReg;

      if (expected.NeedsMap()) {
        DCHECK((instr->temp1() != NULL) && (instr->temp2() != NULL));
        map = ToRegister(instr->temp1());
        scratch = ToRegister(instr->temp2());

        __ Ldr(map, FieldMemOperand(value, HeapObject::kMapOffset));

        if (expected.CanBeUndetectable()) {
          // Undetectable -> false.
          __ Ldrb(scratch, FieldMemOperand(map, Map::kBitFieldOffset));
          __ TestAndBranchIfAnySet(
              scratch, 1 << Map::kIsUndetectable, false_label);
        }
      }

      if (expected.Contains(ToBooleanICStub::SPEC_OBJECT)) {
        // spec object -> true.
        __ CompareInstanceType(map, scratch, FIRST_JS_RECEIVER_TYPE);
        __ B(ge, true_label);
      }

      if (expected.Contains(ToBooleanICStub::STRING)) {
        // String value -> false iff empty.
        Label not_string;
        __ CompareInstanceType(map, scratch, FIRST_NONSTRING_TYPE);
        __ B(ge, &not_string);
        __ Ldr(scratch, FieldMemOperand(value, String::kLengthOffset));
        __ Cbz(scratch, false_label);
        __ B(true_label);
        __ Bind(&not_string);
      }

      if (expected.Contains(ToBooleanICStub::SYMBOL)) {
        // Symbol value -> true.
        __ CompareInstanceType(map, scratch, SYMBOL_TYPE);
        __ B(eq, true_label);
      }

      if (expected.Contains(ToBooleanICStub::SIMD_VALUE)) {
        // SIMD value -> true.
        __ CompareInstanceType(map, scratch, SIMD128_VALUE_TYPE);
        __ B(eq, true_label);
      }

      if (expected.Contains(ToBooleanICStub::HEAP_NUMBER)) {
        Label not_heap_number;
        __ JumpIfNotRoot(map, Heap::kHeapNumberMapRootIndex, &not_heap_number);

        __ Ldr(double_scratch(),
               FieldMemOperand(value, HeapNumber::kValueOffset));
        __ Fcmp(double_scratch(), 0.0);
        // If we got a NaN (overflow bit is set), jump to the false branch.
        __ B(vs, false_label);
        __ B(eq, false_label);
        __ B(true_label);
        __ Bind(&not_heap_number);
      }

      if (!expected.IsGeneric()) {
        // We've seen something for the first time -> deopt.
        // This can only happen if we are not generic already.
        Deoptimize(instr, Deoptimizer::kUnexpectedObject);
      }
    }
  }
}

void LCodeGen::CallKnownFunction(Handle<JSFunction> function,
                                 int formal_parameter_count, int arity,
                                 bool is_tail_call, LInstruction* instr) {
  bool dont_adapt_arguments =
      formal_parameter_count == SharedFunctionInfo::kDontAdaptArgumentsSentinel;
  bool can_invoke_directly =
      dont_adapt_arguments || formal_parameter_count == arity;

  // The function interface relies on the following register assignments.
  Register function_reg = x1;
  Register arity_reg = x0;

  LPointerMap* pointers = instr->pointer_map();

  if (FLAG_debug_code) {
    Label is_not_smi;
    // Try to confirm that function_reg (x1) is a tagged pointer.
    __ JumpIfNotSmi(function_reg, &is_not_smi);
    __ Abort(kExpectedFunctionObject);
    __ Bind(&is_not_smi);
  }

  if (can_invoke_directly) {
    // Change context.
    __ Ldr(cp, FieldMemOperand(function_reg, JSFunction::kContextOffset));

    // Always initialize new target and number of actual arguments.
    __ LoadRoot(x3, Heap::kUndefinedValueRootIndex);
    __ Mov(arity_reg, arity);

    bool is_self_call = function.is_identical_to(info()->closure());

    // Invoke function.
    if (is_self_call) {
      Handle<Code> self(reinterpret_cast<Code**>(__ CodeObject().location()));
      if (is_tail_call) {
        __ Jump(self, RelocInfo::CODE_TARGET);
      } else {
        __ Call(self, RelocInfo::CODE_TARGET);
      }
    } else {
      __ Ldr(x10, FieldMemOperand(function_reg, JSFunction::kCodeEntryOffset));
      if (is_tail_call) {
        __ Jump(x10);
      } else {
        __ Call(x10);
      }
    }

    if (!is_tail_call) {
      // Set up deoptimization.
      RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
    }
  } else {
    SafepointGenerator generator(this, pointers, Safepoint::kLazyDeopt);
    ParameterCount actual(arity);
    ParameterCount expected(formal_parameter_count);
    InvokeFlag flag = is_tail_call ? JUMP_FUNCTION : CALL_FUNCTION;
    __ InvokeFunction(function_reg, expected, actual, flag, generator);
  }
}

void LCodeGen::DoCallWithDescriptor(LCallWithDescriptor* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToRegister(instr->result()).Is(x0));

  if (instr->hydrogen()->IsTailCall()) {
    if (NeedsEagerFrame()) __ LeaveFrame(StackFrame::INTERNAL);

    if (instr->target()->IsConstantOperand()) {
      LConstantOperand* target = LConstantOperand::cast(instr->target());
      Handle<Code> code = Handle<Code>::cast(ToHandle(target));
      // TODO(all): on ARM we use a call descriptor to specify a storage mode
      // but on ARM64 we only have one storage mode so it isn't necessary. Check
      // this understanding is correct.
      __ Jump(code, RelocInfo::CODE_TARGET);
    } else {
      DCHECK(instr->target()->IsRegister());
      Register target = ToRegister(instr->target());
      __ Add(target, target, Code::kHeaderSize - kHeapObjectTag);
      __ Br(target);
    }
  } else {
    LPointerMap* pointers = instr->pointer_map();
    SafepointGenerator generator(this, pointers, Safepoint::kLazyDeopt);

    if (instr->target()->IsConstantOperand()) {
      LConstantOperand* target = LConstantOperand::cast(instr->target());
      Handle<Code> code = Handle<Code>::cast(ToHandle(target));
      generator.BeforeCall(__ CallSize(code, RelocInfo::CODE_TARGET));
      // TODO(all): on ARM we use a call descriptor to specify a storage mode
      // but on ARM64 we only have one storage mode so it isn't necessary. Check
      // this understanding is correct.
      __ Call(code, RelocInfo::CODE_TARGET, TypeFeedbackId::None());
    } else {
      DCHECK(instr->target()->IsRegister());
      Register target = ToRegister(instr->target());
      generator.BeforeCall(__ CallSize(target));
      __ Add(target, target, Code::kHeaderSize - kHeapObjectTag);
      __ Call(target);
    }
    generator.AfterCall();
  }

  RecordPushedArgumentsDelta(instr->hydrogen()->argument_delta());
}


void LCodeGen::DoCallRuntime(LCallRuntime* instr) {
  CallRuntime(instr->function(), instr->arity(), instr);
  RecordPushedArgumentsDelta(instr->hydrogen()->argument_delta());
}


void LCodeGen::DoUnknownOSRValue(LUnknownOSRValue* instr) {
  GenerateOsrPrologue();
}


void LCodeGen::DoDeferredInstanceMigration(LCheckMaps* instr, Register object) {
  Register temp = ToRegister(instr->temp());
  {
    PushSafepointRegistersScope scope(this);
    __ Push(object);
    __ Mov(cp, 0);
    __ CallRuntimeSaveDoubles(Runtime::kTryMigrateInstance);
    RecordSafepointWithRegisters(
        instr->pointer_map(), 1, Safepoint::kNoLazyDeopt);
    __ StoreToSafepointRegisterSlot(x0, temp);
  }
  DeoptimizeIfSmi(temp, instr, Deoptimizer::kInstanceMigrationFailed);
}


void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
  class DeferredCheckMaps: public LDeferredCode {
   public:
    DeferredCheckMaps(LCodeGen* codegen, LCheckMaps* instr, Register object)
        : LDeferredCode(codegen), instr_(instr), object_(object) {
      SetExit(check_maps());
    }
    virtual void Generate() {
      codegen()->DoDeferredInstanceMigration(instr_, object_);
    }
    Label* check_maps() { return &check_maps_; }
    virtual LInstruction* instr() { return instr_; }
   private:
    LCheckMaps* instr_;
    Label check_maps_;
    Register object_;
  };

  if (instr->hydrogen()->IsStabilityCheck()) {
    const UniqueSet<Map>* maps = instr->hydrogen()->maps();
    for (int i = 0; i < maps->size(); ++i) {
      AddStabilityDependency(maps->at(i).handle());
    }
    return;
  }

  Register object = ToRegister(instr->value());
  Register map_reg = ToRegister(instr->temp());

  __ Ldr(map_reg, FieldMemOperand(object, HeapObject::kMapOffset));

  DeferredCheckMaps* deferred = NULL;
  if (instr->hydrogen()->HasMigrationTarget()) {
    deferred = new(zone()) DeferredCheckMaps(this, instr, object);
    __ Bind(deferred->check_maps());
  }

  const UniqueSet<Map>* maps = instr->hydrogen()->maps();
  Label success;
  for (int i = 0; i < maps->size() - 1; i++) {
    Handle<Map> map = maps->at(i).handle();
    __ CompareMap(map_reg, map);
    __ B(eq, &success);
  }
  Handle<Map> map = maps->at(maps->size() - 1).handle();
  __ CompareMap(map_reg, map);

  // We didn't match a map.
  if (instr->hydrogen()->HasMigrationTarget()) {
    __ B(ne, deferred->entry());
  } else {
    DeoptimizeIf(ne, instr, Deoptimizer::kWrongMap);
  }

  __ Bind(&success);
}


void LCodeGen::DoCheckNonSmi(LCheckNonSmi* instr) {
  if (!instr->hydrogen()->value()->type().IsHeapObject()) {
    DeoptimizeIfSmi(ToRegister(instr->value()), instr, Deoptimizer::kSmi);
  }
}


void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
  Register value = ToRegister(instr->value());
  DCHECK(!instr->result() || ToRegister(instr->result()).Is(value));
  DeoptimizeIfNotSmi(value, instr, Deoptimizer::kNotASmi);
}


void LCodeGen::DoCheckArrayBufferNotNeutered(
    LCheckArrayBufferNotNeutered* instr) {
  UseScratchRegisterScope temps(masm());
  Register view = ToRegister(instr->view());
  Register scratch = temps.AcquireX();

  __ Ldr(scratch, FieldMemOperand(view, JSArrayBufferView::kBufferOffset));
  __ Ldr(scratch, FieldMemOperand(scratch, JSArrayBuffer::kBitFieldOffset));
  __ Tst(scratch, Operand(1 << JSArrayBuffer::WasNeutered::kShift));
  DeoptimizeIf(ne, instr, Deoptimizer::kOutOfBounds);
}


void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
  Register input = ToRegister(instr->value());
  Register scratch = ToRegister(instr->temp());

  __ Ldr(scratch, FieldMemOperand(input, HeapObject::kMapOffset));
  __ Ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));

  if (instr->hydrogen()->is_interval_check()) {
    InstanceType first, last;
    instr->hydrogen()->GetCheckInterval(&first, &last);

    __ Cmp(scratch, first);
    if (first == last) {
      // If there is only one type in the interval check for equality.
      DeoptimizeIf(ne, instr, Deoptimizer::kWrongInstanceType);
    } else if (last == LAST_TYPE) {
      // We don't need to compare with the higher bound of the interval.
      DeoptimizeIf(lo, instr, Deoptimizer::kWrongInstanceType);
    } else {
      // If we are below the lower bound, set the C flag and clear the Z flag
      // to force a deopt.
      __ Ccmp(scratch, last, CFlag, hs);
      DeoptimizeIf(hi, instr, Deoptimizer::kWrongInstanceType);
    }
  } else {
    uint8_t mask;
    uint8_t tag;
    instr->hydrogen()->GetCheckMaskAndTag(&mask, &tag);

    if (base::bits::IsPowerOfTwo32(mask)) {
      DCHECK((tag == 0) || (tag == mask));
      if (tag == 0) {
        DeoptimizeIfBitSet(scratch, MaskToBit(mask), instr,
                           Deoptimizer::kWrongInstanceType);
      } else {
        DeoptimizeIfBitClear(scratch, MaskToBit(mask), instr,
                             Deoptimizer::kWrongInstanceType);
      }
    } else {
      if (tag == 0) {
        __ Tst(scratch, mask);
      } else {
        __ And(scratch, scratch, mask);
        __ Cmp(scratch, tag);
      }
      DeoptimizeIf(ne, instr, Deoptimizer::kWrongInstanceType);
    }
  }
}


void LCodeGen::DoClampDToUint8(LClampDToUint8* instr) {
  DoubleRegister input = ToDoubleRegister(instr->unclamped());
  Register result = ToRegister32(instr->result());
  __ ClampDoubleToUint8(result, input, double_scratch());
}


void LCodeGen::DoClampIToUint8(LClampIToUint8* instr) {
  Register input = ToRegister32(instr->unclamped());
  Register result = ToRegister32(instr->result());
  __ ClampInt32ToUint8(result, input);
}


void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
  Register input = ToRegister(instr->unclamped());
  Register result = ToRegister32(instr->result());
  Label done;

  // Both smi and heap number cases are handled.
  Label is_not_smi;
  __ JumpIfNotSmi(input, &is_not_smi);
  __ SmiUntag(result.X(), input);
  __ ClampInt32ToUint8(result);
  __ B(&done);

  __ Bind(&is_not_smi);

  // Check for heap number.
  Label is_heap_number;
  __ JumpIfHeapNumber(input, &is_heap_number);

  // Check for undefined. Undefined is coverted to zero for clamping conversion.
  DeoptimizeIfNotRoot(input, Heap::kUndefinedValueRootIndex, instr,
                      Deoptimizer::kNotAHeapNumberUndefined);
  __ Mov(result, 0);
  __ B(&done);

  // Heap number case.
  __ Bind(&is_heap_number);
  DoubleRegister dbl_scratch = double_scratch();
  DoubleRegister dbl_scratch2 = ToDoubleRegister(instr->temp1());
  __ Ldr(dbl_scratch, FieldMemOperand(input, HeapNumber::kValueOffset));
  __ ClampDoubleToUint8(result, dbl_scratch, dbl_scratch2);

  __ Bind(&done);
}


void LCodeGen::DoDoubleBits(LDoubleBits* instr) {
  DoubleRegister value_reg = ToDoubleRegister(instr->value());
  Register result_reg = ToRegister(instr->result());
  if (instr->hydrogen()->bits() == HDoubleBits::HIGH) {
    __ Fmov(result_reg, value_reg);
    __ Lsr(result_reg, result_reg, 32);
  } else {
    __ Fmov(result_reg.W(), value_reg.S());
  }
}


void LCodeGen::DoClassOfTestAndBranch(LClassOfTestAndBranch* instr) {
  Handle<String> class_name = instr->hydrogen()->class_name();
  Label* true_label = instr->TrueLabel(chunk_);
  Label* false_label = instr->FalseLabel(chunk_);
  Register input = ToRegister(instr->value());
  Register scratch1 = ToRegister(instr->temp1());
  Register scratch2 = ToRegister(instr->temp2());

  __ JumpIfSmi(input, false_label);

  Register map = scratch2;
  __ CompareObjectType(input, map, scratch1, FIRST_FUNCTION_TYPE);
  STATIC_ASSERT(LAST_FUNCTION_TYPE == LAST_TYPE);
  if (String::Equals(isolate()->factory()->Function_string(), class_name)) {
    __ B(hs, true_label);
  } else {
    __ B(hs, false_label);
  }

  // Check if the constructor in the map is a function.
  {
    UseScratchRegisterScope temps(masm());
    Register instance_type = temps.AcquireX();
    __ GetMapConstructor(scratch1, map, scratch2, instance_type);
    __ Cmp(instance_type, JS_FUNCTION_TYPE);
  }
  // Objects with a non-function constructor have class 'Object'.
  if (String::Equals(class_name, isolate()->factory()->Object_string())) {
    __ B(ne, true_label);
  } else {
    __ B(ne, false_label);
  }

  // The constructor function is in scratch1. Get its instance class name.
  __ Ldr(scratch1,
         FieldMemOperand(scratch1, JSFunction::kSharedFunctionInfoOffset));
  __ Ldr(scratch1,
         FieldMemOperand(scratch1,
                         SharedFunctionInfo::kInstanceClassNameOffset));

  // The class name we are testing against is internalized since it's a literal.
  // The name in the constructor is internalized because of the way the context
  // is booted. This routine isn't expected to work for random API-created
  // classes and it doesn't have to because you can't access it with natives
  // syntax. Since both sides are internalized it is sufficient to use an
  // identity comparison.
  EmitCompareAndBranch(instr, eq, scratch1, Operand(class_name));
}


void LCodeGen::DoCmpHoleAndBranchD(LCmpHoleAndBranchD* instr) {
  DCHECK(instr->hydrogen()->representation().IsDouble());
  FPRegister object = ToDoubleRegister(instr->object());
  Register temp = ToRegister(instr->temp());

  // If we don't have a NaN, we don't have the hole, so branch now to avoid the
  // (relatively expensive) hole-NaN check.
  __ Fcmp(object, object);
  __ B(vc, instr->FalseLabel(chunk_));

  // We have a NaN, but is it the hole?
  __ Fmov(temp, object);
  EmitCompareAndBranch(instr, eq, temp, kHoleNanInt64);
}


void LCodeGen::DoCmpHoleAndBranchT(LCmpHoleAndBranchT* instr) {
  DCHECK(instr->hydrogen()->representation().IsTagged());
  Register object = ToRegister(instr->object());

  EmitBranchIfRoot(instr, object, Heap::kTheHoleValueRootIndex);
}


void LCodeGen::DoCmpMapAndBranch(LCmpMapAndBranch* instr) {
  Register value = ToRegister(instr->value());
  Register map = ToRegister(instr->temp());

  __ Ldr(map, FieldMemOperand(value, HeapObject::kMapOffset));
  EmitCompareAndBranch(instr, eq, map, Operand(instr->map()));
}


void LCodeGen::DoCompareNumericAndBranch(LCompareNumericAndBranch* instr) {
  LOperand* left = instr->left();
  LOperand* right = instr->right();
  bool is_unsigned =
      instr->hydrogen()->left()->CheckFlag(HInstruction::kUint32) ||
      instr->hydrogen()->right()->CheckFlag(HInstruction::kUint32);
  Condition cond = TokenToCondition(instr->op(), is_unsigned);

  if (left->IsConstantOperand() && right->IsConstantOperand()) {
    // We can statically evaluate the comparison.
    double left_val = ToDouble(LConstantOperand::cast(left));
    double right_val = ToDouble(LConstantOperand::cast(right));
    int next_block = Token::EvalComparison(instr->op(), left_val, right_val)
                         ? instr->TrueDestination(chunk_)
                         : instr->FalseDestination(chunk_);
    EmitGoto(next_block);
  } else {
    if (instr->is_double()) {
      __ Fcmp(ToDoubleRegister(left), ToDoubleRegister(right));

      // If a NaN is involved, i.e. the result is unordered (V set),
      // jump to false block label.
      __ B(vs, instr->FalseLabel(chunk_));
      EmitBranch(instr, cond);
    } else {
      if (instr->hydrogen_value()->representation().IsInteger32()) {
        if (right->IsConstantOperand()) {
          EmitCompareAndBranch(instr, cond, ToRegister32(left),
                               ToOperand32(right));
        } else {
          // Commute the operands and the condition.
          EmitCompareAndBranch(instr, CommuteCondition(cond),
                               ToRegister32(right), ToOperand32(left));
        }
      } else {
        DCHECK(instr->hydrogen_value()->representation().IsSmi());
        if (right->IsConstantOperand()) {
          int32_t value = ToInteger32(LConstantOperand::cast(right));
          EmitCompareAndBranch(instr,
                               cond,
                               ToRegister(left),
                               Operand(Smi::FromInt(value)));
        } else if (left->IsConstantOperand()) {
          // Commute the operands and the condition.
          int32_t value = ToInteger32(LConstantOperand::cast(left));
          EmitCompareAndBranch(instr,
                               CommuteCondition(cond),
                               ToRegister(right),
                               Operand(Smi::FromInt(value)));
        } else {
          EmitCompareAndBranch(instr,
                               cond,
                               ToRegister(left),
                               ToRegister(right));
        }
      }
    }
  }
}


void LCodeGen::DoCmpObjectEqAndBranch(LCmpObjectEqAndBranch* instr) {
  Register left = ToRegister(instr->left());
  Register right = ToRegister(instr->right());
  EmitCompareAndBranch(instr, eq, left, right);
}


void LCodeGen::DoCmpT(LCmpT* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  Token::Value op = instr->op();
  Condition cond = TokenToCondition(op, false);

  DCHECK(ToRegister(instr->left()).Is(x1));
  DCHECK(ToRegister(instr->right()).Is(x0));
  Handle<Code> ic = CodeFactory::CompareIC(isolate(), op).code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);
  // Signal that we don't inline smi code before this stub.
  InlineSmiCheckInfo::EmitNotInlined(masm());

  // Return true or false depending on CompareIC result.
  // This instruction is marked as call. We can clobber any register.
  DCHECK(instr->IsMarkedAsCall());
  __ LoadTrueFalseRoots(x1, x2);
  __ Cmp(x0, 0);
  __ Csel(ToRegister(instr->result()), x1, x2, cond);
}


void LCodeGen::DoConstantD(LConstantD* instr) {
  DCHECK(instr->result()->IsDoubleRegister());
  DoubleRegister result = ToDoubleRegister(instr->result());
  if (instr->value() == 0) {
    if (copysign(1.0, instr->value()) == 1.0) {
      __ Fmov(result, fp_zero);
    } else {
      __ Fneg(result, fp_zero);
    }
  } else {
    __ Fmov(result, instr->value());
  }
}


void LCodeGen::DoConstantE(LConstantE* instr) {
  __ Mov(ToRegister(instr->result()), Operand(instr->value()));
}


void LCodeGen::DoConstantI(LConstantI* instr) {
  DCHECK(is_int32(instr->value()));
  // Cast the value here to ensure that the value isn't sign extended by the
  // implicit Operand constructor.
  __ Mov(ToRegister32(instr->result()), static_cast<uint32_t>(instr->value()));
}


void LCodeGen::DoConstantS(LConstantS* instr) {
  __ Mov(ToRegister(instr->result()), Operand(instr->value()));
}


void LCodeGen::DoConstantT(LConstantT* instr) {
  Handle<Object> object = instr->value(isolate());
  AllowDeferredHandleDereference smi_check;
  __ LoadObject(ToRegister(instr->result()), object);
}


void LCodeGen::DoContext(LContext* instr) {
  // If there is a non-return use, the context must be moved to a register.
  Register result = ToRegister(instr->result());
  if (info()->IsOptimizing()) {
    __ Ldr(result, MemOperand(fp, StandardFrameConstants::kContextOffset));
  } else {
    // If there is no frame, the context must be in cp.
    DCHECK(result.is(cp));
  }
}


void LCodeGen::DoCheckValue(LCheckValue* instr) {
  Register reg = ToRegister(instr->value());
  Handle<HeapObject> object = instr->hydrogen()->object().handle();
  AllowDeferredHandleDereference smi_check;
  if (isolate()->heap()->InNewSpace(*object)) {
    UseScratchRegisterScope temps(masm());
    Register temp = temps.AcquireX();
    Handle<Cell> cell = isolate()->factory()->NewCell(object);
    __ Mov(temp, Operand(cell));
    __ Ldr(temp, FieldMemOperand(temp, Cell::kValueOffset));
    __ Cmp(reg, temp);
  } else {
    __ Cmp(reg, Operand(object));
  }
  DeoptimizeIf(ne, instr, Deoptimizer::kValueMismatch);
}


void LCodeGen::DoLazyBailout(LLazyBailout* instr) {
  last_lazy_deopt_pc_ = masm()->pc_offset();
  DCHECK(instr->HasEnvironment());
  LEnvironment* env = instr->environment();
  RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
  safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
}


void LCodeGen::DoDeoptimize(LDeoptimize* instr) {
  Deoptimizer::BailoutType type = instr->hydrogen()->type();
  // TODO(danno): Stubs expect all deopts to be lazy for historical reasons (the
  // needed return address), even though the implementation of LAZY and EAGER is
  // now identical. When LAZY is eventually completely folded into EAGER, remove
  // the special case below.
  if (info()->IsStub() && (type == Deoptimizer::EAGER)) {
    type = Deoptimizer::LAZY;
  }

  Deoptimize(instr, instr->hydrogen()->reason(), &type);
}


void LCodeGen::DoDivByPowerOf2I(LDivByPowerOf2I* instr) {
  Register dividend = ToRegister32(instr->dividend());
  int32_t divisor = instr->divisor();
  Register result = ToRegister32(instr->result());
  DCHECK(divisor == kMinInt || base::bits::IsPowerOfTwo32(Abs(divisor)));
  DCHECK(!result.is(dividend));

  // Check for (0 / -x) that will produce negative zero.
  HDiv* hdiv = instr->hydrogen();
  if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
    DeoptimizeIfZero(dividend, instr, Deoptimizer::kDivisionByZero);
  }
  // Check for (kMinInt / -1).
  if (hdiv->CheckFlag(HValue::kCanOverflow) && divisor == -1) {
    // Test dividend for kMinInt by subtracting one (cmp) and checking for
    // overflow.
    __ Cmp(dividend, 1);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  }
  // Deoptimize if remainder will not be 0.
  if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32) &&
      divisor != 1 && divisor != -1) {
    int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1);
    __ Tst(dividend, mask);
    DeoptimizeIf(ne, instr, Deoptimizer::kLostPrecision);
  }

  if (divisor == -1) {  // Nice shortcut, not needed for correctness.
    __ Neg(result, dividend);
    return;
  }
  int32_t shift = WhichPowerOf2Abs(divisor);
  if (shift == 0) {
    __ Mov(result, dividend);
  } else if (shift == 1) {
    __ Add(result, dividend, Operand(dividend, LSR, 31));
  } else {
    __ Mov(result, Operand(dividend, ASR, 31));
    __ Add(result, dividend, Operand(result, LSR, 32 - shift));
  }
  if (shift > 0) __ Mov(result, Operand(result, ASR, shift));
  if (divisor < 0) __ Neg(result, result);
}


void LCodeGen::DoDivByConstI(LDivByConstI* instr) {
  Register dividend = ToRegister32(instr->dividend());
  int32_t divisor = instr->divisor();
  Register result = ToRegister32(instr->result());
  DCHECK(!AreAliased(dividend, result));

  if (divisor == 0) {
    Deoptimize(instr, Deoptimizer::kDivisionByZero);
    return;
  }

  // Check for (0 / -x) that will produce negative zero.
  HDiv* hdiv = instr->hydrogen();
  if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
    DeoptimizeIfZero(dividend, instr, Deoptimizer::kMinusZero);
  }

  __ TruncatingDiv(result, dividend, Abs(divisor));
  if (divisor < 0) __ Neg(result, result);

  if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
    Register temp = ToRegister32(instr->temp());
    DCHECK(!AreAliased(dividend, result, temp));
    __ Sxtw(dividend.X(), dividend);
    __ Mov(temp, divisor);
    __ Smsubl(temp.X(), result, temp, dividend.X());
    DeoptimizeIfNotZero(temp, instr, Deoptimizer::kLostPrecision);
  }
}


// TODO(svenpanne) Refactor this to avoid code duplication with DoFlooringDivI.
void LCodeGen::DoDivI(LDivI* instr) {
  HBinaryOperation* hdiv = instr->hydrogen();
  Register dividend = ToRegister32(instr->dividend());
  Register divisor = ToRegister32(instr->divisor());
  Register result = ToRegister32(instr->result());

  // Issue the division first, and then check for any deopt cases whilst the
  // result is computed.
  __ Sdiv(result, dividend, divisor);

  if (hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
    DCHECK(!instr->temp());
    return;
  }

  // Check for x / 0.
  if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
    DeoptimizeIfZero(divisor, instr, Deoptimizer::kDivisionByZero);
  }

  // Check for (0 / -x) as that will produce negative zero.
  if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
    __ Cmp(divisor, 0);

    // If the divisor < 0 (mi), compare the dividend, and deopt if it is
    // zero, ie. zero dividend with negative divisor deopts.
    // If the divisor >= 0 (pl, the opposite of mi) set the flags to
    // condition ne, so we don't deopt, ie. positive divisor doesn't deopt.
    __ Ccmp(dividend, 0, NoFlag, mi);
    DeoptimizeIf(eq, instr, Deoptimizer::kMinusZero);
  }

  // Check for (kMinInt / -1).
  if (hdiv->CheckFlag(HValue::kCanOverflow)) {
    // Test dividend for kMinInt by subtracting one (cmp) and checking for
    // overflow.
    __ Cmp(dividend, 1);
    // If overflow is set, ie. dividend = kMinInt, compare the divisor with
    // -1. If overflow is clear, set the flags for condition ne, as the
    // dividend isn't -1, and thus we shouldn't deopt.
    __ Ccmp(divisor, -1, NoFlag, vs);
    DeoptimizeIf(eq, instr, Deoptimizer::kOverflow);
  }

  // Compute remainder and deopt if it's not zero.
  Register remainder = ToRegister32(instr->temp());
  __ Msub(remainder, result, divisor, dividend);
  DeoptimizeIfNotZero(remainder, instr, Deoptimizer::kLostPrecision);
}


void LCodeGen::DoDoubleToIntOrSmi(LDoubleToIntOrSmi* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  Register result = ToRegister32(instr->result());

  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    DeoptimizeIfMinusZero(input, instr, Deoptimizer::kMinusZero);
  }

  __ TryRepresentDoubleAsInt32(result, input, double_scratch());
  DeoptimizeIf(ne, instr, Deoptimizer::kLostPrecisionOrNaN);

  if (instr->tag_result()) {
    __ SmiTag(result.X());
  }
}


void LCodeGen::DoDrop(LDrop* instr) {
  __ Drop(instr->count());

  RecordPushedArgumentsDelta(instr->hydrogen_value()->argument_delta());
}


void LCodeGen::DoDummy(LDummy* instr) {
  // Nothing to see here, move on!
}


void LCodeGen::DoDummyUse(LDummyUse* instr) {
  // Nothing to see here, move on!
}


void LCodeGen::DoForInCacheArray(LForInCacheArray* instr) {
  Register map = ToRegister(instr->map());
  Register result = ToRegister(instr->result());
  Label load_cache, done;

  __ EnumLengthUntagged(result, map);
  __ Cbnz(result, &load_cache);

  __ Mov(result, Operand(isolate()->factory()->empty_fixed_array()));
  __ B(&done);

  __ Bind(&load_cache);
  __ LoadInstanceDescriptors(map, result);
  __ Ldr(result, FieldMemOperand(result, DescriptorArray::kEnumCacheOffset));
  __ Ldr(result, FieldMemOperand(result, FixedArray::SizeFor(instr->idx())));
  DeoptimizeIfZero(result, instr, Deoptimizer::kNoCache);

  __ Bind(&done);
}


void LCodeGen::DoForInPrepareMap(LForInPrepareMap* instr) {
  Register object = ToRegister(instr->object());

  DCHECK(instr->IsMarkedAsCall());
  DCHECK(object.Is(x0));

  Label use_cache, call_runtime;
  __ CheckEnumCache(object, x5, x1, x2, x3, x4, &call_runtime);

  __ Ldr(object, FieldMemOperand(object, HeapObject::kMapOffset));
  __ B(&use_cache);

  // Get the set of properties to enumerate.
  __ Bind(&call_runtime);
  __ Push(object);
  CallRuntime(Runtime::kForInEnumerate, instr);
  __ Bind(&use_cache);
}


void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
  Register input = ToRegister(instr->value());
  Register result = ToRegister(instr->result());

  __ AssertString(input);

  // Assert that we can use a W register load to get the hash.
  DCHECK((String::kHashShift + String::kArrayIndexValueBits) < kWRegSizeInBits);
  __ Ldr(result.W(), FieldMemOperand(input, String::kHashFieldOffset));
  __ IndexFromHash(result, result);
}


void LCodeGen::EmitGoto(int block) {
  // Do not emit jump if we are emitting a goto to the next block.
  if (!IsNextEmittedBlock(block)) {
    __ B(chunk_->GetAssemblyLabel(LookupDestination(block)));
  }
}


void LCodeGen::DoGoto(LGoto* instr) {
  EmitGoto(instr->block_id());
}


void LCodeGen::DoHasCachedArrayIndexAndBranch(
    LHasCachedArrayIndexAndBranch* instr) {
  Register input = ToRegister(instr->value());
  Register temp = ToRegister32(instr->temp());

  // Assert that the cache status bits fit in a W register.
  DCHECK(is_uint32(String::kContainsCachedArrayIndexMask));
  __ Ldr(temp, FieldMemOperand(input, String::kHashFieldOffset));
  __ Tst(temp, String::kContainsCachedArrayIndexMask);
  EmitBranch(instr, eq);
}


// HHasInstanceTypeAndBranch instruction is built with an interval of type
// to test but is only used in very restricted ways. The only possible kinds
// of intervals are:
//  - [ FIRST_TYPE, instr->to() ]
//  - [ instr->form(), LAST_TYPE ]
//  - instr->from() == instr->to()
//
// These kinds of intervals can be check with only one compare instruction
// providing the correct value and test condition are used.
//
// TestType() will return the value to use in the compare instruction and
// BranchCondition() will return the condition to use depending on the kind
// of interval actually specified in the instruction.
static InstanceType TestType(HHasInstanceTypeAndBranch* instr) {
  InstanceType from = instr->from();
  InstanceType to = instr->to();
  if (from == FIRST_TYPE) return to;
  DCHECK((from == to) || (to == LAST_TYPE));
  return from;
}


// See comment above TestType function for what this function does.
static Condition BranchCondition(HHasInstanceTypeAndBranch* instr) {
  InstanceType from = instr->from();
  InstanceType to = instr->to();
  if (from == to) return eq;
  if (to == LAST_TYPE) return hs;
  if (from == FIRST_TYPE) return ls;
  UNREACHABLE();
  return eq;
}


void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
  Register input = ToRegister(instr->value());
  Register scratch = ToRegister(instr->temp());

  if (!instr->hydrogen()->value()->type().IsHeapObject()) {
    __ JumpIfSmi(input, instr->FalseLabel(chunk_));
  }
  __ CompareObjectType(input, scratch, scratch, TestType(instr->hydrogen()));
  EmitBranch(instr, BranchCondition(instr->hydrogen()));
}


void LCodeGen::DoInnerAllocatedObject(LInnerAllocatedObject* instr) {
  Register result = ToRegister(instr->result());
  Register base = ToRegister(instr->base_object());
  if (instr->offset()->IsConstantOperand()) {
    __ Add(result, base, ToOperand32(instr->offset()));
  } else {
    __ Add(result, base, Operand(ToRegister32(instr->offset()), SXTW));
  }
}


void LCodeGen::DoHasInPrototypeChainAndBranch(
    LHasInPrototypeChainAndBranch* instr) {
  Register const object = ToRegister(instr->object());
  Register const object_map = ToRegister(instr->scratch1());
  Register const object_instance_type = ToRegister(instr->scratch2());
  Register const object_prototype = object_map;
  Register const prototype = ToRegister(instr->prototype());

  // The {object} must be a spec object.  It's sufficient to know that {object}
  // is not a smi, since all other non-spec objects have {null} prototypes and
  // will be ruled out below.
  if (instr->hydrogen()->ObjectNeedsSmiCheck()) {
    __ JumpIfSmi(object, instr->FalseLabel(chunk_));
  }

  // Loop through the {object}s prototype chain looking for the {prototype}.
  __ Ldr(object_map, FieldMemOperand(object, HeapObject::kMapOffset));
  Label loop;
  __ Bind(&loop);

  // Deoptimize if the object needs to be access checked.
  __ Ldrb(object_instance_type,
          FieldMemOperand(object_map, Map::kBitFieldOffset));
  __ Tst(object_instance_type, Operand(1 << Map::kIsAccessCheckNeeded));
  DeoptimizeIf(ne, instr, Deoptimizer::kAccessCheck);
  // Deoptimize for proxies.
  __ CompareInstanceType(object_map, object_instance_type, JS_PROXY_TYPE);
  DeoptimizeIf(eq, instr, Deoptimizer::kProxy);

  __ Ldr(object_prototype, FieldMemOperand(object_map, Map::kPrototypeOffset));
  __ CompareRoot(object_prototype, Heap::kNullValueRootIndex);
  __ B(eq, instr->FalseLabel(chunk_));
  __ Cmp(object_prototype, prototype);
  __ B(eq, instr->TrueLabel(chunk_));
  __ Ldr(object_map, FieldMemOperand(object_prototype, HeapObject::kMapOffset));
  __ B(&loop);
}


void LCodeGen::DoInstructionGap(LInstructionGap* instr) {
  DoGap(instr);
}


void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
  Register value = ToRegister32(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());
  __ Scvtf(result, value);
}

void LCodeGen::PrepareForTailCall(const ParameterCount& actual,
                                  Register scratch1, Register scratch2,
                                  Register scratch3) {
#if DEBUG
  if (actual.is_reg()) {
    DCHECK(!AreAliased(actual.reg(), scratch1, scratch2, scratch3));
  } else {
    DCHECK(!AreAliased(scratch1, scratch2, scratch3));
  }
#endif
  if (FLAG_code_comments) {
    if (actual.is_reg()) {
      Comment(";;; PrepareForTailCall, actual: %s {",
              RegisterConfiguration::Crankshaft()->GetGeneralRegisterName(
                  actual.reg().code()));
    } else {
      Comment(";;; PrepareForTailCall, actual: %d {", actual.immediate());
    }
  }

  // Check if next frame is an arguments adaptor frame.
  Register caller_args_count_reg = scratch1;
  Label no_arguments_adaptor, formal_parameter_count_loaded;
  __ Ldr(scratch2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ Ldr(scratch3,
         MemOperand(scratch2, StandardFrameConstants::kContextOffset));
  __ Cmp(scratch3, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
  __ B(ne, &no_arguments_adaptor);

  // Drop current frame and load arguments count from arguments adaptor frame.
  __ mov(fp, scratch2);
  __ Ldr(caller_args_count_reg,
         MemOperand(fp, ArgumentsAdaptorFrameConstants::kLengthOffset));
  __ SmiUntag(caller_args_count_reg);
  __ B(&formal_parameter_count_loaded);

  __ bind(&no_arguments_adaptor);
  // Load caller's formal parameter count
  __ Mov(caller_args_count_reg,
         Immediate(info()->literal()->parameter_count()));

  __ bind(&formal_parameter_count_loaded);
  __ PrepareForTailCall(actual, caller_args_count_reg, scratch2, scratch3);

  Comment(";;; }");
}

void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
  HInvokeFunction* hinstr = instr->hydrogen();
  DCHECK(ToRegister(instr->context()).is(cp));
  // The function is required to be in x1.
  DCHECK(ToRegister(instr->function()).is(x1));
  DCHECK(instr->HasPointerMap());

  bool is_tail_call = hinstr->tail_call_mode() == TailCallMode::kAllow;

  if (is_tail_call) {
    DCHECK(!info()->saves_caller_doubles());
    ParameterCount actual(instr->arity());
    // It is safe to use x3, x4 and x5 as scratch registers here given that
    // 1) we are not going to return to caller function anyway,
    // 2) x3 (new.target) will be initialized below.
    PrepareForTailCall(actual, x3, x4, x5);
  }

  Handle<JSFunction> known_function = hinstr->known_function();
  if (known_function.is_null()) {
    LPointerMap* pointers = instr->pointer_map();
    SafepointGenerator generator(this, pointers, Safepoint::kLazyDeopt);
    ParameterCount actual(instr->arity());
    InvokeFlag flag = is_tail_call ? JUMP_FUNCTION : CALL_FUNCTION;
    __ InvokeFunction(x1, no_reg, actual, flag, generator);
  } else {
    CallKnownFunction(known_function, hinstr->formal_parameter_count(),
                      instr->arity(), is_tail_call, instr);
  }
  RecordPushedArgumentsDelta(instr->hydrogen()->argument_delta());
}


Condition LCodeGen::EmitIsString(Register input,
                                 Register temp1,
                                 Label* is_not_string,
                                 SmiCheck check_needed = INLINE_SMI_CHECK) {
  if (check_needed == INLINE_SMI_CHECK) {
    __ JumpIfSmi(input, is_not_string);
  }
  __ CompareObjectType(input, temp1, temp1, FIRST_NONSTRING_TYPE);

  return lt;
}


void LCodeGen::DoIsStringAndBranch(LIsStringAndBranch* instr) {
  Register val = ToRegister(instr->value());
  Register scratch = ToRegister(instr->temp());

  SmiCheck check_needed =
      instr->hydrogen()->value()->type().IsHeapObject()
          ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
  Condition true_cond =
      EmitIsString(val, scratch, instr->FalseLabel(chunk_), check_needed);

  EmitBranch(instr, true_cond);
}


void LCodeGen::DoIsSmiAndBranch(LIsSmiAndBranch* instr) {
  Register value = ToRegister(instr->value());
  STATIC_ASSERT(kSmiTag == 0);
  EmitTestAndBranch(instr, eq, value, kSmiTagMask);
}


void LCodeGen::DoIsUndetectableAndBranch(LIsUndetectableAndBranch* instr) {
  Register input = ToRegister(instr->value());
  Register temp = ToRegister(instr->temp());

  if (!instr->hydrogen()->value()->type().IsHeapObject()) {
    __ JumpIfSmi(input, instr->FalseLabel(chunk_));
  }
  __ Ldr(temp, FieldMemOperand(input, HeapObject::kMapOffset));
  __ Ldrb(temp, FieldMemOperand(temp, Map::kBitFieldOffset));

  EmitTestAndBranch(instr, ne, temp, 1 << Map::kIsUndetectable);
}


static const char* LabelType(LLabel* label) {
  if (label->is_loop_header()) return " (loop header)";
  if (label->is_osr_entry()) return " (OSR entry)";
  return "";
}


void LCodeGen::DoLabel(LLabel* label) {
  Comment(";;; <@%d,#%d> -------------------- B%d%s --------------------",
          current_instruction_,
          label->hydrogen_value()->id(),
          label->block_id(),
          LabelType(label));

  // Inherit pushed_arguments_ from the predecessor's argument count.
  if (label->block()->HasPredecessor()) {
    pushed_arguments_ = label->block()->predecessors()->at(0)->argument_count();
#ifdef DEBUG
    for (auto p : *label->block()->predecessors()) {
      DCHECK_EQ(p->argument_count(), pushed_arguments_);
    }
#endif
  }

  __ Bind(label->label());
  current_block_ = label->block_id();
  DoGap(label);
}


void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
  Register context = ToRegister(instr->context());
  Register result = ToRegister(instr->result());
  __ Ldr(result, ContextMemOperand(context, instr->slot_index()));
  if (instr->hydrogen()->RequiresHoleCheck()) {
    if (instr->hydrogen()->DeoptimizesOnHole()) {
      DeoptimizeIfRoot(result, Heap::kTheHoleValueRootIndex, instr,
                       Deoptimizer::kHole);
    } else {
      Label not_the_hole;
      __ JumpIfNotRoot(result, Heap::kTheHoleValueRootIndex, &not_the_hole);
      __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
      __ Bind(&not_the_hole);
    }
  }
}


void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
  Register function = ToRegister(instr->function());
  Register result = ToRegister(instr->result());
  Register temp = ToRegister(instr->temp());

  // Get the prototype or initial map from the function.
  __ Ldr(result, FieldMemOperand(function,
                                 JSFunction::kPrototypeOrInitialMapOffset));

  // Check that the function has a prototype or an initial map.
  DeoptimizeIfRoot(result, Heap::kTheHoleValueRootIndex, instr,
                   Deoptimizer::kHole);

  // If the function does not have an initial map, we're done.
  Label done;
  __ CompareObjectType(result, temp, temp, MAP_TYPE);
  __ B(ne, &done);

  // Get the prototype from the initial map.
  __ Ldr(result, FieldMemOperand(result, Map::kPrototypeOffset));

  // All done.
  __ Bind(&done);
}


template <class T>
void LCodeGen::EmitVectorLoadICRegisters(T* instr) {
  Register vector_register = ToRegister(instr->temp_vector());
  Register slot_register = LoadWithVectorDescriptor::SlotRegister();
  DCHECK(vector_register.is(LoadWithVectorDescriptor::VectorRegister()));
  DCHECK(slot_register.is(x0));

  AllowDeferredHandleDereference vector_structure_check;
  Handle<TypeFeedbackVector> vector = instr->hydrogen()->feedback_vector();
  __ Mov(vector_register, vector);
  // No need to allocate this register.
  FeedbackVectorSlot slot = instr->hydrogen()->slot();
  int index = vector->GetIndex(slot);
  __ Mov(slot_register, Smi::FromInt(index));
}


template <class T>
void LCodeGen::EmitVectorStoreICRegisters(T* instr) {
  Register vector_register = ToRegister(instr->temp_vector());
  Register slot_register = ToRegister(instr->temp_slot());

  AllowDeferredHandleDereference vector_structure_check;
  Handle<TypeFeedbackVector> vector = instr->hydrogen()->feedback_vector();
  __ Mov(vector_register, vector);
  FeedbackVectorSlot slot = instr->hydrogen()->slot();
  int index = vector->GetIndex(slot);
  __ Mov(slot_register, Smi::FromInt(index));
}


void LCodeGen::DoLoadGlobalGeneric(LLoadGlobalGeneric* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->result()).Is(x0));

  EmitVectorLoadICRegisters<LLoadGlobalGeneric>(instr);
  Handle<Code> ic =
      CodeFactory::LoadGlobalICInOptimizedCode(isolate(), instr->typeof_mode())
          .code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);
}


MemOperand LCodeGen::PrepareKeyedExternalArrayOperand(
    Register key,
    Register base,
    Register scratch,
    bool key_is_smi,
    bool key_is_constant,
    int constant_key,
    ElementsKind elements_kind,
    int base_offset) {
  int element_size_shift = ElementsKindToShiftSize(elements_kind);

  if (key_is_constant) {
    int key_offset = constant_key << element_size_shift;
    return MemOperand(base, key_offset + base_offset);
  }

  if (key_is_smi) {
    __ Add(scratch, base, Operand::UntagSmiAndScale(key, element_size_shift));
    return MemOperand(scratch, base_offset);
  }

  if (base_offset == 0) {
    return MemOperand(base, key, SXTW, element_size_shift);
  }

  DCHECK(!AreAliased(scratch, key));
  __ Add(scratch, base, base_offset);
  return MemOperand(scratch, key, SXTW, element_size_shift);
}


void LCodeGen::DoLoadKeyedExternal(LLoadKeyedExternal* instr) {
  Register ext_ptr = ToRegister(instr->elements());
  Register scratch;
  ElementsKind elements_kind = instr->elements_kind();

  bool key_is_smi = instr->hydrogen()->key()->representation().IsSmi();
  bool key_is_constant = instr->key()->IsConstantOperand();
  Register key = no_reg;
  int constant_key = 0;
  if (key_is_constant) {
    DCHECK(instr->temp() == NULL);
    constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
    if (constant_key & 0xf0000000) {
      Abort(kArrayIndexConstantValueTooBig);
    }
  } else {
    scratch = ToRegister(instr->temp());
    key = ToRegister(instr->key());
  }

  MemOperand mem_op =
      PrepareKeyedExternalArrayOperand(key, ext_ptr, scratch, key_is_smi,
                                       key_is_constant, constant_key,
                                       elements_kind,
                                       instr->base_offset());

  if (elements_kind == FLOAT32_ELEMENTS) {
    DoubleRegister result = ToDoubleRegister(instr->result());
    __ Ldr(result.S(), mem_op);
    __ Fcvt(result, result.S());
  } else if (elements_kind == FLOAT64_ELEMENTS) {
    DoubleRegister result = ToDoubleRegister(instr->result());
    __ Ldr(result, mem_op);
  } else {
    Register result = ToRegister(instr->result());

    switch (elements_kind) {
      case INT8_ELEMENTS:
        __ Ldrsb(result, mem_op);
        break;
      case UINT8_ELEMENTS:
      case UINT8_CLAMPED_ELEMENTS:
        __ Ldrb(result, mem_op);
        break;
      case INT16_ELEMENTS:
        __ Ldrsh(result, mem_op);
        break;
      case UINT16_ELEMENTS:
        __ Ldrh(result, mem_op);
        break;
      case INT32_ELEMENTS:
        __ Ldrsw(result, mem_op);
        break;
      case UINT32_ELEMENTS:
        __ Ldr(result.W(), mem_op);
        if (!instr->hydrogen()->CheckFlag(HInstruction::kUint32)) {
          // Deopt if value > 0x80000000.
          __ Tst(result, 0xFFFFFFFF80000000);
          DeoptimizeIf(ne, instr, Deoptimizer::kNegativeValue);
        }
        break;
      case FLOAT32_ELEMENTS:
      case FLOAT64_ELEMENTS:
      case FAST_HOLEY_DOUBLE_ELEMENTS:
      case FAST_HOLEY_ELEMENTS:
      case FAST_HOLEY_SMI_ELEMENTS:
      case FAST_DOUBLE_ELEMENTS:
      case FAST_ELEMENTS:
      case FAST_SMI_ELEMENTS:
      case DICTIONARY_ELEMENTS:
      case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
      case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
      case FAST_STRING_WRAPPER_ELEMENTS:
      case SLOW_STRING_WRAPPER_ELEMENTS:
      case NO_ELEMENTS:
        UNREACHABLE();
        break;
    }
  }
}


MemOperand LCodeGen::PrepareKeyedArrayOperand(Register base,
                                              Register elements,
                                              Register key,
                                              bool key_is_tagged,
                                              ElementsKind elements_kind,
                                              Representation representation,
                                              int base_offset) {
  STATIC_ASSERT(static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits);
  STATIC_ASSERT(kSmiTag == 0);
  int element_size_shift = ElementsKindToShiftSize(elements_kind);

  // Even though the HLoad/StoreKeyed instructions force the input
  // representation for the key to be an integer, the input gets replaced during
  // bounds check elimination with the index argument to the bounds check, which
  // can be tagged, so that case must be handled here, too.
  if (key_is_tagged) {
    __ Add(base, elements, Operand::UntagSmiAndScale(key, element_size_shift));
    if (representation.IsInteger32()) {
      DCHECK(elements_kind == FAST_SMI_ELEMENTS);
      // Read or write only the smi payload in the case of fast smi arrays.
      return UntagSmiMemOperand(base, base_offset);
    } else {
      return MemOperand(base, base_offset);
    }
  } else {
    // Sign extend key because it could be a 32-bit negative value or contain
    // garbage in the top 32-bits. The address computation happens in 64-bit.
    DCHECK((element_size_shift >= 0) && (element_size_shift <= 4));
    if (representation.IsInteger32()) {
      DCHECK(elements_kind == FAST_SMI_ELEMENTS);
      // Read or write only the smi payload in the case of fast smi arrays.
      __ Add(base, elements, Operand(key, SXTW, element_size_shift));
      return UntagSmiMemOperand(base, base_offset);
    } else {
      __ Add(base, elements, base_offset);
      return MemOperand(base, key, SXTW, element_size_shift);
    }
  }
}


void LCodeGen::DoLoadKeyedFixedDouble(LLoadKeyedFixedDouble* instr) {
  Register elements = ToRegister(instr->elements());
  DoubleRegister result = ToDoubleRegister(instr->result());
  MemOperand mem_op;

  if (instr->key()->IsConstantOperand()) {
    DCHECK(instr->hydrogen()->RequiresHoleCheck() ||
           (instr->temp() == NULL));

    int constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
    if (constant_key & 0xf0000000) {
      Abort(kArrayIndexConstantValueTooBig);
    }
    int offset = instr->base_offset() + constant_key * kDoubleSize;
    mem_op = MemOperand(elements, offset);
  } else {
    Register load_base = ToRegister(instr->temp());
    Register key = ToRegister(instr->key());
    bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();
    mem_op = PrepareKeyedArrayOperand(load_base, elements, key, key_is_tagged,
                                      instr->hydrogen()->elements_kind(),
                                      instr->hydrogen()->representation(),
                                      instr->base_offset());
  }

  __ Ldr(result, mem_op);

  if (instr->hydrogen()->RequiresHoleCheck()) {
    Register scratch = ToRegister(instr->temp());
    __ Fmov(scratch, result);
    __ Eor(scratch, scratch, kHoleNanInt64);
    DeoptimizeIfZero(scratch, instr, Deoptimizer::kHole);
  }
}


void LCodeGen::DoLoadKeyedFixed(LLoadKeyedFixed* instr) {
  Register elements = ToRegister(instr->elements());
  Register result = ToRegister(instr->result());
  MemOperand mem_op;

  Representation representation = instr->hydrogen()->representation();
  if (instr->key()->IsConstantOperand()) {
    DCHECK(instr->temp() == NULL);
    LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
    int offset = instr->base_offset() +
        ToInteger32(const_operand) * kPointerSize;
    if (representation.IsInteger32()) {
      DCHECK(instr->hydrogen()->elements_kind() == FAST_SMI_ELEMENTS);
      STATIC_ASSERT(static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits);
      STATIC_ASSERT(kSmiTag == 0);
      mem_op = UntagSmiMemOperand(elements, offset);
    } else {
      mem_op = MemOperand(elements, offset);
    }
  } else {
    Register load_base = ToRegister(instr->temp());
    Register key = ToRegister(instr->key());
    bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();

    mem_op = PrepareKeyedArrayOperand(load_base, elements, key, key_is_tagged,
                                      instr->hydrogen()->elements_kind(),
                                      representation, instr->base_offset());
  }

  __ Load(result, mem_op, representation);

  if (instr->hydrogen()->RequiresHoleCheck()) {
    if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
      DeoptimizeIfNotSmi(result, instr, Deoptimizer::kNotASmi);
    } else {
      DeoptimizeIfRoot(result, Heap::kTheHoleValueRootIndex, instr,
                       Deoptimizer::kHole);
    }
  } else if (instr->hydrogen()->hole_mode() == CONVERT_HOLE_TO_UNDEFINED) {
    DCHECK(instr->hydrogen()->elements_kind() == FAST_HOLEY_ELEMENTS);
    Label done;
    __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
    __ B(ne, &done);
    if (info()->IsStub()) {
      // A stub can safely convert the hole to undefined only if the array
      // protector cell contains (Smi) Isolate::kArrayProtectorValid. Otherwise
      // it needs to bail out.
      __ LoadRoot(result, Heap::kArrayProtectorRootIndex);
      __ Ldr(result, FieldMemOperand(result, Cell::kValueOffset));
      __ Cmp(result, Operand(Smi::FromInt(Isolate::kArrayProtectorValid)));
      DeoptimizeIf(ne, instr, Deoptimizer::kHole);
    }
    __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
    __ Bind(&done);
  }
}


void LCodeGen::DoLoadKeyedGeneric(LLoadKeyedGeneric* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->object()).is(LoadDescriptor::ReceiverRegister()));
  DCHECK(ToRegister(instr->key()).is(LoadDescriptor::NameRegister()));

  EmitVectorLoadICRegisters<LLoadKeyedGeneric>(instr);

  Handle<Code> ic = CodeFactory::KeyedLoadICInOptimizedCode(isolate()).code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);

  DCHECK(ToRegister(instr->result()).Is(x0));
}


void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
  HObjectAccess access = instr->hydrogen()->access();
  int offset = access.offset();
  Register object = ToRegister(instr->object());

  if (access.IsExternalMemory()) {
    Register result = ToRegister(instr->result());
    __ Load(result, MemOperand(object, offset), access.representation());
    return;
  }

  if (instr->hydrogen()->representation().IsDouble()) {
    DCHECK(access.IsInobject());
    FPRegister result = ToDoubleRegister(instr->result());
    __ Ldr(result, FieldMemOperand(object, offset));
    return;
  }

  Register result = ToRegister(instr->result());
  Register source;
  if (access.IsInobject()) {
    source = object;
  } else {
    // Load the properties array, using result as a scratch register.
    __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
    source = result;
  }

  if (access.representation().IsSmi() &&
      instr->hydrogen()->representation().IsInteger32()) {
    // Read int value directly from upper half of the smi.
    STATIC_ASSERT(static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits);
    STATIC_ASSERT(kSmiTag == 0);
    __ Load(result, UntagSmiFieldMemOperand(source, offset),
            Representation::Integer32());
  } else {
    __ Load(result, FieldMemOperand(source, offset), access.representation());
  }
}


void LCodeGen::DoLoadNamedGeneric(LLoadNamedGeneric* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  // LoadIC expects name and receiver in registers.
  DCHECK(ToRegister(instr->object()).is(LoadDescriptor::ReceiverRegister()));
  __ Mov(LoadDescriptor::NameRegister(), Operand(instr->name()));
  EmitVectorLoadICRegisters<LLoadNamedGeneric>(instr);
  Handle<Code> ic = CodeFactory::LoadICInOptimizedCode(isolate()).code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);

  DCHECK(ToRegister(instr->result()).is(x0));
}


void LCodeGen::DoLoadRoot(LLoadRoot* instr) {
  Register result = ToRegister(instr->result());
  __ LoadRoot(result, instr->index());
}


void LCodeGen::DoMathAbs(LMathAbs* instr) {
  Representation r = instr->hydrogen()->value()->representation();
  if (r.IsDouble()) {
    DoubleRegister input = ToDoubleRegister(instr->value());
    DoubleRegister result = ToDoubleRegister(instr->result());
    __ Fabs(result, input);
  } else if (r.IsSmi() || r.IsInteger32()) {
    Register input = r.IsSmi() ? ToRegister(instr->value())
                               : ToRegister32(instr->value());
    Register result = r.IsSmi() ? ToRegister(instr->result())
                                : ToRegister32(instr->result());
    __ Abs(result, input);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  }
}


void LCodeGen::DoDeferredMathAbsTagged(LMathAbsTagged* instr,
                                       Label* exit,
                                       Label* allocation_entry) {
  // Handle the tricky cases of MathAbsTagged:
  //  - HeapNumber inputs.
  //    - Negative inputs produce a positive result, so a new HeapNumber is
  //      allocated to hold it.
  //    - Positive inputs are returned as-is, since there is no need to allocate
  //      a new HeapNumber for the result.
  //  - The (smi) input -0x80000000, produces +0x80000000, which does not fit
  //    a smi. In this case, the inline code sets the result and jumps directly
  //    to the allocation_entry label.
  DCHECK(instr->context() != NULL);
  DCHECK(ToRegister(instr->context()).is(cp));
  Register input = ToRegister(instr->value());
  Register temp1 = ToRegister(instr->temp1());
  Register temp2 = ToRegister(instr->temp2());
  Register result_bits = ToRegister(instr->temp3());
  Register result = ToRegister(instr->result());

  Label runtime_allocation;

  // Deoptimize if the input is not a HeapNumber.
  DeoptimizeIfNotHeapNumber(input, instr);

  // If the argument is positive, we can return it as-is, without any need to
  // allocate a new HeapNumber for the result. We have to do this in integer
  // registers (rather than with fabs) because we need to be able to distinguish
  // the two zeroes.
  __ Ldr(result_bits, FieldMemOperand(input, HeapNumber::kValueOffset));
  __ Mov(result, input);
  __ Tbz(result_bits, kXSignBit, exit);

  // Calculate abs(input) by clearing the sign bit.
  __ Bic(result_bits, result_bits, kXSignMask);

  // Allocate a new HeapNumber to hold the result.
  //  result_bits   The bit representation of the (double) result.
  __ Bind(allocation_entry);
  __ AllocateHeapNumber(result, &runtime_allocation, temp1, temp2);
  // The inline (non-deferred) code will store result_bits into result.
  __ B(exit);

  __ Bind(&runtime_allocation);
  if (FLAG_debug_code) {
    // Because result is in the pointer map, we need to make sure it has a valid
    // tagged value before we call the runtime. We speculatively set it to the
    // input (for abs(+x)) or to a smi (for abs(-SMI_MIN)), so it should already
    // be valid.
    Label result_ok;
    Register input = ToRegister(instr->value());
    __ JumpIfSmi(result, &result_ok);
    __ Cmp(input, result);
    __ Assert(eq, kUnexpectedValue);
    __ Bind(&result_ok);
  }

  { PushSafepointRegistersScope scope(this);
    CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr,
                            instr->context());
    __ StoreToSafepointRegisterSlot(x0, result);
  }
  // The inline (non-deferred) code will store result_bits into result.
}


void LCodeGen::DoMathAbsTagged(LMathAbsTagged* instr) {
  // Class for deferred case.
  class DeferredMathAbsTagged: public LDeferredCode {
   public:
    DeferredMathAbsTagged(LCodeGen* codegen, LMathAbsTagged* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() {
      codegen()->DoDeferredMathAbsTagged(instr_, exit(),
                                         allocation_entry());
    }
    virtual LInstruction* instr() { return instr_; }
    Label* allocation_entry() { return &allocation; }
   private:
    LMathAbsTagged* instr_;
    Label allocation;
  };

  // TODO(jbramley): The early-exit mechanism would skip the new frame handling
  // in GenerateDeferredCode. Tidy this up.
  DCHECK(!NeedsDeferredFrame());

  DeferredMathAbsTagged* deferred =
      new(zone()) DeferredMathAbsTagged(this, instr);

  DCHECK(instr->hydrogen()->value()->representation().IsTagged() ||
         instr->hydrogen()->value()->representation().IsSmi());
  Register input = ToRegister(instr->value());
  Register result_bits = ToRegister(instr->temp3());
  Register result = ToRegister(instr->result());
  Label done;

  // Handle smis inline.
  // We can treat smis as 64-bit integers, since the (low-order) tag bits will
  // never get set by the negation. This is therefore the same as the Integer32
  // case in DoMathAbs, except that it operates on 64-bit values.
  STATIC_ASSERT((kSmiValueSize == 32) && (kSmiShift == 32) && (kSmiTag == 0));

  __ JumpIfNotSmi(input, deferred->entry());

  __ Abs(result, input, NULL, &done);

  // The result is the magnitude (abs) of the smallest value a smi can
  // represent, encoded as a double.
  __ Mov(result_bits, double_to_rawbits(0x80000000));
  __ B(deferred->allocation_entry());

  __ Bind(deferred->exit());
  __ Str(result_bits, FieldMemOperand(result, HeapNumber::kValueOffset));

  __ Bind(&done);
}

void LCodeGen::DoMathCos(LMathCos* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToDoubleRegister(instr->value()).is(d0));
  __ CallCFunction(ExternalReference::ieee754_cos_function(isolate()), 0, 1);
  DCHECK(ToDoubleRegister(instr->result()).Is(d0));
}

void LCodeGen::DoMathSin(LMathSin* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToDoubleRegister(instr->value()).is(d0));
  __ CallCFunction(ExternalReference::ieee754_sin_function(isolate()), 0, 1);
  DCHECK(ToDoubleRegister(instr->result()).Is(d0));
}

void LCodeGen::DoMathExp(LMathExp* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToDoubleRegister(instr->value()).is(d0));
  __ CallCFunction(ExternalReference::ieee754_exp_function(isolate()), 0, 1);
  DCHECK(ToDoubleRegister(instr->result()).Is(d0));
}


void LCodeGen::DoMathFloorD(LMathFloorD* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());

  __ Frintm(result, input);
}


void LCodeGen::DoMathFloorI(LMathFloorI* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  Register result = ToRegister(instr->result());

  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    DeoptimizeIfMinusZero(input, instr, Deoptimizer::kMinusZero);
  }

  __ Fcvtms(result, input);

  // Check that the result fits into a 32-bit integer.
  //  - The result did not overflow.
  __ Cmp(result, Operand(result, SXTW));
  //  - The input was not NaN.
  __ Fccmp(input, input, NoFlag, eq);
  DeoptimizeIf(ne, instr, Deoptimizer::kLostPrecisionOrNaN);
}


void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
  Register dividend = ToRegister32(instr->dividend());
  Register result = ToRegister32(instr->result());
  int32_t divisor = instr->divisor();

  // If the divisor is 1, return the dividend.
  if (divisor == 1) {
    __ Mov(result, dividend, kDiscardForSameWReg);
    return;
  }

  // If the divisor is positive, things are easy: There can be no deopts and we
  // can simply do an arithmetic right shift.
  int32_t shift = WhichPowerOf2Abs(divisor);
  if (divisor > 1) {
    __ Mov(result, Operand(dividend, ASR, shift));
    return;
  }

  // If the divisor is negative, we have to negate and handle edge cases.
  __ Negs(result, dividend);
  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    DeoptimizeIf(eq, instr, Deoptimizer::kMinusZero);
  }

  // Dividing by -1 is basically negation, unless we overflow.
  if (divisor == -1) {
    if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
      DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
    }
    return;
  }

  // If the negation could not overflow, simply shifting is OK.
  if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
    __ Mov(result, Operand(dividend, ASR, shift));
    return;
  }

  __ Asr(result, result, shift);
  __ Csel(result, result, kMinInt / divisor, vc);
}


void LCodeGen::DoFlooringDivByConstI(LFlooringDivByConstI* instr) {
  Register dividend = ToRegister32(instr->dividend());
  int32_t divisor = instr->divisor();
  Register result = ToRegister32(instr->result());
  DCHECK(!AreAliased(dividend, result));

  if (divisor == 0) {
    Deoptimize(instr, Deoptimizer::kDivisionByZero);
    return;
  }

  // Check for (0 / -x) that will produce negative zero.
  HMathFloorOfDiv* hdiv = instr->hydrogen();
  if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
    DeoptimizeIfZero(dividend, instr, Deoptimizer::kMinusZero);
  }

  // Easy case: We need no dynamic check for the dividend and the flooring
  // division is the same as the truncating division.
  if ((divisor > 0 && !hdiv->CheckFlag(HValue::kLeftCanBeNegative)) ||
      (divisor < 0 && !hdiv->CheckFlag(HValue::kLeftCanBePositive))) {
    __ TruncatingDiv(result, dividend, Abs(divisor));
    if (divisor < 0) __ Neg(result, result);
    return;
  }

  // In the general case we may need to adjust before and after the truncating
  // division to get a flooring division.
  Register temp = ToRegister32(instr->temp());
  DCHECK(!AreAliased(temp, dividend, result));
  Label needs_adjustment, done;
  __ Cmp(dividend, 0);
  __ B(divisor > 0 ? lt : gt, &needs_adjustment);
  __ TruncatingDiv(result, dividend, Abs(divisor));
  if (divisor < 0) __ Neg(result, result);
  __ B(&done);
  __ Bind(&needs_adjustment);
  __ Add(temp, dividend, Operand(divisor > 0 ? 1 : -1));
  __ TruncatingDiv(result, temp, Abs(divisor));
  if (divisor < 0) __ Neg(result, result);
  __ Sub(result, result, Operand(1));
  __ Bind(&done);
}


// TODO(svenpanne) Refactor this to avoid code duplication with DoDivI.
void LCodeGen::DoFlooringDivI(LFlooringDivI* instr) {
  Register dividend = ToRegister32(instr->dividend());
  Register divisor = ToRegister32(instr->divisor());
  Register remainder = ToRegister32(instr->temp());
  Register result = ToRegister32(instr->result());

  // This can't cause an exception on ARM, so we can speculatively
  // execute it already now.
  __ Sdiv(result, dividend, divisor);

  // Check for x / 0.
  DeoptimizeIfZero(divisor, instr, Deoptimizer::kDivisionByZero);

  // Check for (kMinInt / -1).
  if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
    // The V flag will be set iff dividend == kMinInt.
    __ Cmp(dividend, 1);
    __ Ccmp(divisor, -1, NoFlag, vs);
    DeoptimizeIf(eq, instr, Deoptimizer::kOverflow);
  }

  // Check for (0 / -x) that will produce negative zero.
  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    __ Cmp(divisor, 0);
    __ Ccmp(dividend, 0, ZFlag, mi);
    // "divisor" can't be null because the code would have already been
    // deoptimized. The Z flag is set only if (divisor < 0) and (dividend == 0).
    // In this case we need to deoptimize to produce a -0.
    DeoptimizeIf(eq, instr, Deoptimizer::kMinusZero);
  }

  Label done;
  // If both operands have the same sign then we are done.
  __ Eor(remainder, dividend, divisor);
  __ Tbz(remainder, kWSignBit, &done);

  // Check if the result needs to be corrected.
  __ Msub(remainder, result, divisor, dividend);
  __ Cbz(remainder, &done);
  __ Sub(result, result, 1);

  __ Bind(&done);
}


void LCodeGen::DoMathLog(LMathLog* instr) {
  DCHECK(instr->IsMarkedAsCall());
  DCHECK(ToDoubleRegister(instr->value()).is(d0));
  __ CallCFunction(ExternalReference::ieee754_log_function(isolate()), 0, 1);
  DCHECK(ToDoubleRegister(instr->result()).Is(d0));
}


void LCodeGen::DoMathClz32(LMathClz32* instr) {
  Register input = ToRegister32(instr->value());
  Register result = ToRegister32(instr->result());
  __ Clz(result, input);
}


void LCodeGen::DoMathPowHalf(LMathPowHalf* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());
  Label done;

  // Math.pow(x, 0.5) differs from fsqrt(x) in the following cases:
  //  Math.pow(-Infinity, 0.5) == +Infinity
  //  Math.pow(-0.0, 0.5) == +0.0

  // Catch -infinity inputs first.
  // TODO(jbramley): A constant infinity register would be helpful here.
  __ Fmov(double_scratch(), kFP64NegativeInfinity);
  __ Fcmp(double_scratch(), input);
  __ Fabs(result, input);
  __ B(&done, eq);

  // Add +0.0 to convert -0.0 to +0.0.
  __ Fadd(double_scratch(), input, fp_zero);
  __ Fsqrt(result, double_scratch());

  __ Bind(&done);
}


void LCodeGen::DoPower(LPower* instr) {
  Representation exponent_type = instr->hydrogen()->right()->representation();
  // Having marked this as a call, we can use any registers.
  // Just make sure that the input/output registers are the expected ones.
  Register tagged_exponent = MathPowTaggedDescriptor::exponent();
  Register integer_exponent = MathPowIntegerDescriptor::exponent();
  DCHECK(!instr->right()->IsDoubleRegister() ||
         ToDoubleRegister(instr->right()).is(d1));
  DCHECK(exponent_type.IsInteger32() || !instr->right()->IsRegister() ||
         ToRegister(instr->right()).is(tagged_exponent));
  DCHECK(!exponent_type.IsInteger32() ||
         ToRegister(instr->right()).is(integer_exponent));
  DCHECK(ToDoubleRegister(instr->left()).is(d0));
  DCHECK(ToDoubleRegister(instr->result()).is(d0));

  if (exponent_type.IsSmi()) {
    MathPowStub stub(isolate(), MathPowStub::TAGGED);
    __ CallStub(&stub);
  } else if (exponent_type.IsTagged()) {
    Label no_deopt;
    __ JumpIfSmi(tagged_exponent, &no_deopt);
    DeoptimizeIfNotHeapNumber(tagged_exponent, instr);
    __ Bind(&no_deopt);
    MathPowStub stub(isolate(), MathPowStub::TAGGED);
    __ CallStub(&stub);
  } else if (exponent_type.IsInteger32()) {
    // Ensure integer exponent has no garbage in top 32-bits, as MathPowStub
    // supports large integer exponents.
    __ Sxtw(integer_exponent, integer_exponent);
    MathPowStub stub(isolate(), MathPowStub::INTEGER);
    __ CallStub(&stub);
  } else {
    DCHECK(exponent_type.IsDouble());
    MathPowStub stub(isolate(), MathPowStub::DOUBLE);
    __ CallStub(&stub);
  }
}


void LCodeGen::DoMathRoundD(LMathRoundD* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());
  DoubleRegister scratch_d = double_scratch();

  DCHECK(!AreAliased(input, result, scratch_d));

  Label done;

  __ Frinta(result, input);
  __ Fcmp(input, 0.0);
  __ Fccmp(result, input, ZFlag, lt);
  // The result is correct if the input was in [-0, +infinity], or was a
  // negative integral value.
  __ B(eq, &done);

  // Here the input is negative, non integral, with an exponent lower than 52.
  // We do not have to worry about the 0.49999999999999994 (0x3fdfffffffffffff)
  // case. So we can safely add 0.5.
  __ Fmov(scratch_d, 0.5);
  __ Fadd(result, input, scratch_d);
  __ Frintm(result, result);
  // The range [-0.5, -0.0[ yielded +0.0. Force the sign to negative.
  __ Fabs(result, result);
  __ Fneg(result, result);

  __ Bind(&done);
}


void LCodeGen::DoMathRoundI(LMathRoundI* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister temp = ToDoubleRegister(instr->temp1());
  DoubleRegister dot_five = double_scratch();
  Register result = ToRegister(instr->result());
  Label done;

  // Math.round() rounds to the nearest integer, with ties going towards
  // +infinity. This does not match any IEEE-754 rounding mode.
  //  - Infinities and NaNs are propagated unchanged, but cause deopts because
  //    they can't be represented as integers.
  //  - The sign of the result is the same as the sign of the input. This means
  //    that -0.0 rounds to itself, and values -0.5 <= input < 0 also produce a
  //    result of -0.0.

  // Add 0.5 and round towards -infinity.
  __ Fmov(dot_five, 0.5);
  __ Fadd(temp, input, dot_five);
  __ Fcvtms(result, temp);

  // The result is correct if:
  //  result is not 0, as the input could be NaN or [-0.5, -0.0].
  //  result is not 1, as 0.499...94 will wrongly map to 1.
  //  result fits in 32 bits.
  __ Cmp(result, Operand(result.W(), SXTW));
  __ Ccmp(result, 1, ZFlag, eq);
  __ B(hi, &done);

  // At this point, we have to handle possible inputs of NaN or numbers in the
  // range [-0.5, 1.5[, or numbers larger than 32 bits.

  // Deoptimize if the result > 1, as it must be larger than 32 bits.
  __ Cmp(result, 1);
  DeoptimizeIf(hi, instr, Deoptimizer::kOverflow);

  // Deoptimize for negative inputs, which at this point are only numbers in
  // the range [-0.5, -0.0]
  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    __ Fmov(result, input);
    DeoptimizeIfNegative(result, instr, Deoptimizer::kMinusZero);
  }

  // Deoptimize if the input was NaN.
  __ Fcmp(input, dot_five);
  DeoptimizeIf(vs, instr, Deoptimizer::kNaN);

  // Now, the only unhandled inputs are in the range [0.0, 1.5[ (or [-0.5, 1.5[
  // if we didn't generate a -0.0 bailout). If input >= 0.5 then return 1,
  // else 0; we avoid dealing with 0.499...94 directly.
  __ Cset(result, ge);
  __ Bind(&done);
}


void LCodeGen::DoMathFround(LMathFround* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());
  __ Fcvt(result.S(), input);
  __ Fcvt(result, result.S());
}


void LCodeGen::DoMathSqrt(LMathSqrt* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  DoubleRegister result = ToDoubleRegister(instr->result());
  __ Fsqrt(result, input);
}


void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
  HMathMinMax::Operation op = instr->hydrogen()->operation();
  if (instr->hydrogen()->representation().IsInteger32()) {
    Register result = ToRegister32(instr->result());
    Register left = ToRegister32(instr->left());
    Operand right = ToOperand32(instr->right());

    __ Cmp(left, right);
    __ Csel(result, left, right, (op == HMathMinMax::kMathMax) ? ge : le);
  } else if (instr->hydrogen()->representation().IsSmi()) {
    Register result = ToRegister(instr->result());
    Register left = ToRegister(instr->left());
    Operand right = ToOperand(instr->right());

    __ Cmp(left, right);
    __ Csel(result, left, right, (op == HMathMinMax::kMathMax) ? ge : le);
  } else {
    DCHECK(instr->hydrogen()->representation().IsDouble());
    DoubleRegister result = ToDoubleRegister(instr->result());
    DoubleRegister left = ToDoubleRegister(instr->left());
    DoubleRegister right = ToDoubleRegister(instr->right());

    if (op == HMathMinMax::kMathMax) {
      __ Fmax(result, left, right);
    } else {
      DCHECK(op == HMathMinMax::kMathMin);
      __ Fmin(result, left, right);
    }
  }
}


void LCodeGen::DoModByPowerOf2I(LModByPowerOf2I* instr) {
  Register dividend = ToRegister32(instr->dividend());
  int32_t divisor = instr->divisor();
  DCHECK(dividend.is(ToRegister32(instr->result())));

  // Theoretically, a variation of the branch-free code for integer division by
  // a power of 2 (calculating the remainder via an additional multiplication
  // (which gets simplified to an 'and') and subtraction) should be faster, and
  // this is exactly what GCC and clang emit. Nevertheless, benchmarks seem to
  // indicate that positive dividends are heavily favored, so the branching
  // version performs better.
  HMod* hmod = instr->hydrogen();
  int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1);
  Label dividend_is_not_negative, done;
  if (hmod->CheckFlag(HValue::kLeftCanBeNegative)) {
    __ Tbz(dividend, kWSignBit, &dividend_is_not_negative);
    // Note that this is correct even for kMinInt operands.
    __ Neg(dividend, dividend);
    __ And(dividend, dividend, mask);
    __ Negs(dividend, dividend);
    if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
      DeoptimizeIf(eq, instr, Deoptimizer::kMinusZero);
    }
    __ B(&done);
  }

  __ bind(&dividend_is_not_negative);
  __ And(dividend, dividend, mask);
  __ bind(&done);
}


void LCodeGen::DoModByConstI(LModByConstI* instr) {
  Register dividend = ToRegister32(instr->dividend());
  int32_t divisor = instr->divisor();
  Register result = ToRegister32(instr->result());
  Register temp = ToRegister32(instr->temp());
  DCHECK(!AreAliased(dividend, result, temp));

  if (divisor == 0) {
    Deoptimize(instr, Deoptimizer::kDivisionByZero);
    return;
  }

  __ TruncatingDiv(result, dividend, Abs(divisor));
  __ Sxtw(dividend.X(), dividend);
  __ Mov(temp, Abs(divisor));
  __ Smsubl(result.X(), result, temp, dividend.X());

  // Check for negative zero.
  HMod* hmod = instr->hydrogen();
  if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
    Label remainder_not_zero;
    __ Cbnz(result, &remainder_not_zero);
    DeoptimizeIfNegative(dividend, instr, Deoptimizer::kMinusZero);
    __ bind(&remainder_not_zero);
  }
}


void LCodeGen::DoModI(LModI* instr) {
  Register dividend = ToRegister32(instr->left());
  Register divisor = ToRegister32(instr->right());
  Register result = ToRegister32(instr->result());

  Label done;
  // modulo = dividend - quotient * divisor
  __ Sdiv(result, dividend, divisor);
  if (instr->hydrogen()->CheckFlag(HValue::kCanBeDivByZero)) {
    DeoptimizeIfZero(divisor, instr, Deoptimizer::kDivisionByZero);
  }
  __ Msub(result, result, divisor, dividend);
  if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
    __ Cbnz(result, &done);
    DeoptimizeIfNegative(dividend, instr, Deoptimizer::kMinusZero);
  }
  __ Bind(&done);
}


void LCodeGen::DoMulConstIS(LMulConstIS* instr) {
  DCHECK(instr->hydrogen()->representation().IsSmiOrInteger32());
  bool is_smi = instr->hydrogen()->representation().IsSmi();
  Register result =
      is_smi ? ToRegister(instr->result()) : ToRegister32(instr->result());
  Register left =
      is_smi ? ToRegister(instr->left()) : ToRegister32(instr->left());
  int32_t right = ToInteger32(instr->right());
  DCHECK((right > -kMaxInt) && (right < kMaxInt));

  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  bool bailout_on_minus_zero =
    instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero);

  if (bailout_on_minus_zero) {
    if (right < 0) {
      // The result is -0 if right is negative and left is zero.
      DeoptimizeIfZero(left, instr, Deoptimizer::kMinusZero);
    } else if (right == 0) {
      // The result is -0 if the right is zero and the left is negative.
      DeoptimizeIfNegative(left, instr, Deoptimizer::kMinusZero);
    }
  }

  switch (right) {
    // Cases which can detect overflow.
    case -1:
      if (can_overflow) {
        // Only 0x80000000 can overflow here.
        __ Negs(result, left);
        DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
      } else {
        __ Neg(result, left);
      }
      break;
    case 0:
      // This case can never overflow.
      __ Mov(result, 0);
      break;
    case 1:
      // This case can never overflow.
      __ Mov(result, left, kDiscardForSameWReg);
      break;
    case 2:
      if (can_overflow) {
        __ Adds(result, left, left);
        DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
      } else {
        __ Add(result, left, left);
      }
      break;

    default:
      // Multiplication by constant powers of two (and some related values)
      // can be done efficiently with shifted operands.
      int32_t right_abs = Abs(right);

      if (base::bits::IsPowerOfTwo32(right_abs)) {
        int right_log2 = WhichPowerOf2(right_abs);

        if (can_overflow) {
          Register scratch = result;
          DCHECK(!AreAliased(scratch, left));
          __ Cls(scratch, left);
          __ Cmp(scratch, right_log2);
          DeoptimizeIf(lt, instr, Deoptimizer::kOverflow);
        }

        if (right >= 0) {
          // result = left << log2(right)
          __ Lsl(result, left, right_log2);
        } else {
          // result = -left << log2(-right)
          if (can_overflow) {
            __ Negs(result, Operand(left, LSL, right_log2));
            DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
          } else {
            __ Neg(result, Operand(left, LSL, right_log2));
          }
        }
        return;
      }


      // For the following cases, we could perform a conservative overflow check
      // with CLS as above. However the few cycles saved are likely not worth
      // the risk of deoptimizing more often than required.
      DCHECK(!can_overflow);

      if (right >= 0) {
        if (base::bits::IsPowerOfTwo32(right - 1)) {
          // result = left + left << log2(right - 1)
          __ Add(result, left, Operand(left, LSL, WhichPowerOf2(right - 1)));
        } else if (base::bits::IsPowerOfTwo32(right + 1)) {
          // result = -left + left << log2(right + 1)
          __ Sub(result, left, Operand(left, LSL, WhichPowerOf2(right + 1)));
          __ Neg(result, result);
        } else {
          UNREACHABLE();
        }
      } else {
        if (base::bits::IsPowerOfTwo32(-right + 1)) {
          // result = left - left << log2(-right + 1)
          __ Sub(result, left, Operand(left, LSL, WhichPowerOf2(-right + 1)));
        } else if (base::bits::IsPowerOfTwo32(-right - 1)) {
          // result = -left - left << log2(-right - 1)
          __ Add(result, left, Operand(left, LSL, WhichPowerOf2(-right - 1)));
          __ Neg(result, result);
        } else {
          UNREACHABLE();
        }
      }
  }
}


void LCodeGen::DoMulI(LMulI* instr) {
  Register result = ToRegister32(instr->result());
  Register left = ToRegister32(instr->left());
  Register right = ToRegister32(instr->right());

  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  bool bailout_on_minus_zero =
    instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero);

  if (bailout_on_minus_zero && !left.Is(right)) {
    // If one operand is zero and the other is negative, the result is -0.
    //  - Set Z (eq) if either left or right, or both, are 0.
    __ Cmp(left, 0);
    __ Ccmp(right, 0, ZFlag, ne);
    //  - If so (eq), set N (mi) if left + right is negative.
    //  - Otherwise, clear N.
    __ Ccmn(left, right, NoFlag, eq);
    DeoptimizeIf(mi, instr, Deoptimizer::kMinusZero);
  }

  if (can_overflow) {
    __ Smull(result.X(), left, right);
    __ Cmp(result.X(), Operand(result, SXTW));
    DeoptimizeIf(ne, instr, Deoptimizer::kOverflow);
  } else {
    __ Mul(result, left, right);
  }
}


void LCodeGen::DoMulS(LMulS* instr) {
  Register result = ToRegister(instr->result());
  Register left = ToRegister(instr->left());
  Register right = ToRegister(instr->right());

  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  bool bailout_on_minus_zero =
    instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero);

  if (bailout_on_minus_zero && !left.Is(right)) {
    // If one operand is zero and the other is negative, the result is -0.
    //  - Set Z (eq) if either left or right, or both, are 0.
    __ Cmp(left, 0);
    __ Ccmp(right, 0, ZFlag, ne);
    //  - If so (eq), set N (mi) if left + right is negative.
    //  - Otherwise, clear N.
    __ Ccmn(left, right, NoFlag, eq);
    DeoptimizeIf(mi, instr, Deoptimizer::kMinusZero);
  }

  STATIC_ASSERT((kSmiShift == 32) && (kSmiTag == 0));
  if (can_overflow) {
    __ Smulh(result, left, right);
    __ Cmp(result, Operand(result.W(), SXTW));
    __ SmiTag(result);
    DeoptimizeIf(ne, instr, Deoptimizer::kOverflow);
  } else {
    if (AreAliased(result, left, right)) {
      // All three registers are the same: half untag the input and then
      // multiply, giving a tagged result.
      STATIC_ASSERT((kSmiShift % 2) == 0);
      __ Asr(result, left, kSmiShift / 2);
      __ Mul(result, result, result);
    } else if (result.Is(left) && !left.Is(right)) {
      // Registers result and left alias, right is distinct: untag left into
      // result, and then multiply by right, giving a tagged result.
      __ SmiUntag(result, left);
      __ Mul(result, result, right);
    } else {
      DCHECK(!left.Is(result));
      // Registers result and right alias, left is distinct, or all registers
      // are distinct: untag right into result, and then multiply by left,
      // giving a tagged result.
      __ SmiUntag(result, right);
      __ Mul(result, left, result);
    }
  }
}


void LCodeGen::DoDeferredNumberTagD(LNumberTagD* instr) {
  // TODO(3095996): Get rid of this. For now, we need to make the
  // result register contain a valid pointer because it is already
  // contained in the register pointer map.
  Register result = ToRegister(instr->result());
  __ Mov(result, 0);

  PushSafepointRegistersScope scope(this);
  // NumberTagU and NumberTagD use the context from the frame, rather than
  // the environment's HContext or HInlinedContext value.
  // They only call Runtime::kAllocateHeapNumber.
  // The corresponding HChange instructions are added in a phase that does
  // not have easy access to the local context.
  __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
  __ CallRuntimeSaveDoubles(Runtime::kAllocateHeapNumber);
  RecordSafepointWithRegisters(
      instr->pointer_map(), 0, Safepoint::kNoLazyDeopt);
  __ StoreToSafepointRegisterSlot(x0, result);
}


void LCodeGen::DoNumberTagD(LNumberTagD* instr) {
  class DeferredNumberTagD: public LDeferredCode {
   public:
    DeferredNumberTagD(LCodeGen* codegen, LNumberTagD* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() { codegen()->DoDeferredNumberTagD(instr_); }
    virtual LInstruction* instr() { return instr_; }
   private:
    LNumberTagD* instr_;
  };

  DoubleRegister input = ToDoubleRegister(instr->value());
  Register result = ToRegister(instr->result());
  Register temp1 = ToRegister(instr->temp1());
  Register temp2 = ToRegister(instr->temp2());

  DeferredNumberTagD* deferred = new(zone()) DeferredNumberTagD(this, instr);
  if (FLAG_inline_new) {
    __ AllocateHeapNumber(result, deferred->entry(), temp1, temp2);
  } else {
    __ B(deferred->entry());
  }

  __ Bind(deferred->exit());
  __ Str(input, FieldMemOperand(result, HeapNumber::kValueOffset));
}


void LCodeGen::DoDeferredNumberTagU(LInstruction* instr,
                                    LOperand* value,
                                    LOperand* temp1,
                                    LOperand* temp2) {
  Label slow, convert_and_store;
  Register src = ToRegister32(value);
  Register dst = ToRegister(instr->result());
  Register scratch1 = ToRegister(temp1);

  if (FLAG_inline_new) {
    Register scratch2 = ToRegister(temp2);
    __ AllocateHeapNumber(dst, &slow, scratch1, scratch2);
    __ B(&convert_and_store);
  }

  // Slow case: call the runtime system to do the number allocation.
  __ Bind(&slow);
  // TODO(3095996): Put a valid pointer value in the stack slot where the result
  // register is stored, as this register is in the pointer map, but contains an
  // integer value.
  __ Mov(dst, 0);
  {
    // Preserve the value of all registers.
    PushSafepointRegistersScope scope(this);

    // NumberTagU and NumberTagD use the context from the frame, rather than
    // the environment's HContext or HInlinedContext value.
    // They only call Runtime::kAllocateHeapNumber.
    // The corresponding HChange instructions are added in a phase that does
    // not have easy access to the local context.
    __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
    __ CallRuntimeSaveDoubles(Runtime::kAllocateHeapNumber);
    RecordSafepointWithRegisters(
      instr->pointer_map(), 0, Safepoint::kNoLazyDeopt);
    __ StoreToSafepointRegisterSlot(x0, dst);
  }

  // Convert number to floating point and store in the newly allocated heap
  // number.
  __ Bind(&convert_and_store);
  DoubleRegister dbl_scratch = double_scratch();
  __ Ucvtf(dbl_scratch, src);
  __ Str(dbl_scratch, FieldMemOperand(dst, HeapNumber::kValueOffset));
}


void LCodeGen::DoNumberTagU(LNumberTagU* instr) {
  class DeferredNumberTagU: public LDeferredCode {
   public:
    DeferredNumberTagU(LCodeGen* codegen, LNumberTagU* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() {
      codegen()->DoDeferredNumberTagU(instr_,
                                      instr_->value(),
                                      instr_->temp1(),
                                      instr_->temp2());
    }
    virtual LInstruction* instr() { return instr_; }
   private:
    LNumberTagU* instr_;
  };

  Register value = ToRegister32(instr->value());
  Register result = ToRegister(instr->result());

  DeferredNumberTagU* deferred = new(zone()) DeferredNumberTagU(this, instr);
  __ Cmp(value, Smi::kMaxValue);
  __ B(hi, deferred->entry());
  __ SmiTag(result, value.X());
  __ Bind(deferred->exit());
}


void LCodeGen::DoNumberUntagD(LNumberUntagD* instr) {
  Register input = ToRegister(instr->value());
  Register scratch = ToRegister(instr->temp());
  DoubleRegister result = ToDoubleRegister(instr->result());
  bool can_convert_undefined_to_nan =
      instr->hydrogen()->can_convert_undefined_to_nan();

  Label done, load_smi;

  // Work out what untag mode we're working with.
  HValue* value = instr->hydrogen()->value();
  NumberUntagDMode mode = value->representation().IsSmi()
      ? NUMBER_CANDIDATE_IS_SMI : NUMBER_CANDIDATE_IS_ANY_TAGGED;

  if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
    __ JumpIfSmi(input, &load_smi);

    Label convert_undefined;

    // Heap number map check.
    if (can_convert_undefined_to_nan) {
      __ JumpIfNotHeapNumber(input, &convert_undefined);
    } else {
      DeoptimizeIfNotHeapNumber(input, instr);
    }

    // Load heap number.
    __ Ldr(result, FieldMemOperand(input, HeapNumber::kValueOffset));
    if (instr->hydrogen()->deoptimize_on_minus_zero()) {
      DeoptimizeIfMinusZero(result, instr, Deoptimizer::kMinusZero);
    }
    __ B(&done);

    if (can_convert_undefined_to_nan) {
      __ Bind(&convert_undefined);
      DeoptimizeIfNotRoot(input, Heap::kUndefinedValueRootIndex, instr,
                          Deoptimizer::kNotAHeapNumberUndefined);

      __ LoadRoot(scratch, Heap::kNanValueRootIndex);
      __ Ldr(result, FieldMemOperand(scratch, HeapNumber::kValueOffset));
      __ B(&done);
    }

  } else {
    DCHECK(mode == NUMBER_CANDIDATE_IS_SMI);
    // Fall through to load_smi.
  }

  // Smi to double register conversion.
  __ Bind(&load_smi);
  __ SmiUntagToDouble(result, input);

  __ Bind(&done);
}


void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
  // This is a pseudo-instruction that ensures that the environment here is
  // properly registered for deoptimization and records the assembler's PC
  // offset.
  LEnvironment* environment = instr->environment();

  // If the environment were already registered, we would have no way of
  // backpatching it with the spill slot operands.
  DCHECK(!environment->HasBeenRegistered());
  RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);

  GenerateOsrPrologue();
}


void LCodeGen::DoParameter(LParameter* instr) {
  // Nothing to do.
}


void LCodeGen::DoPreparePushArguments(LPreparePushArguments* instr) {
  __ PushPreamble(instr->argc(), kPointerSize);
}


void LCodeGen::DoPushArguments(LPushArguments* instr) {
  MacroAssembler::PushPopQueue args(masm());

  for (int i = 0; i < instr->ArgumentCount(); ++i) {
    LOperand* arg = instr->argument(i);
    if (arg->IsDoubleRegister() || arg->IsDoubleStackSlot()) {
      Abort(kDoPushArgumentNotImplementedForDoubleType);
      return;
    }
    args.Queue(ToRegister(arg));
  }

  // The preamble was done by LPreparePushArguments.
  args.PushQueued(MacroAssembler::PushPopQueue::SKIP_PREAMBLE);

  RecordPushedArgumentsDelta(instr->ArgumentCount());
}


void LCodeGen::DoReturn(LReturn* instr) {
  if (FLAG_trace && info()->IsOptimizing()) {
    // Push the return value on the stack as the parameter.
    // Runtime::TraceExit returns its parameter in x0.  We're leaving the code
    // managed by the register allocator and tearing down the frame, it's
    // safe to write to the context register.
    __ Push(x0);
    __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
    __ CallRuntime(Runtime::kTraceExit);
  }

  if (info()->saves_caller_doubles()) {
    RestoreCallerDoubles();
  }

  if (NeedsEagerFrame()) {
    Register stack_pointer = masm()->StackPointer();
    __ Mov(stack_pointer, fp);
    __ Pop(fp, lr);
  }

  if (instr->has_constant_parameter_count()) {
    int parameter_count = ToInteger32(instr->constant_parameter_count());
    __ Drop(parameter_count + 1);
  } else {
    DCHECK(info()->IsStub());  // Functions would need to drop one more value.
    Register parameter_count = ToRegister(instr->parameter_count());
    __ DropBySMI(parameter_count);
  }
  __ Ret();
}


MemOperand LCodeGen::BuildSeqStringOperand(Register string,
                                           Register temp,
                                           LOperand* index,
                                           String::Encoding encoding) {
  if (index->IsConstantOperand()) {
    int offset = ToInteger32(LConstantOperand::cast(index));
    if (encoding == String::TWO_BYTE_ENCODING) {
      offset *= kUC16Size;
    }
    STATIC_ASSERT(kCharSize == 1);
    return FieldMemOperand(string, SeqString::kHeaderSize + offset);
  }

  __ Add(temp, string, SeqString::kHeaderSize - kHeapObjectTag);
  if (encoding == String::ONE_BYTE_ENCODING) {
    return MemOperand(temp, ToRegister32(index), SXTW);
  } else {
    STATIC_ASSERT(kUC16Size == 2);
    return MemOperand(temp, ToRegister32(index), SXTW, 1);
  }
}


void LCodeGen::DoSeqStringGetChar(LSeqStringGetChar* instr) {
  String::Encoding encoding = instr->hydrogen()->encoding();
  Register string = ToRegister(instr->string());
  Register result = ToRegister(instr->result());
  Register temp = ToRegister(instr->temp());

  if (FLAG_debug_code) {
    // Even though this lithium instruction comes with a temp register, we
    // can't use it here because we want to use "AtStart" constraints on the
    // inputs and the debug code here needs a scratch register.
    UseScratchRegisterScope temps(masm());
    Register dbg_temp = temps.AcquireX();

    __ Ldr(dbg_temp, FieldMemOperand(string, HeapObject::kMapOffset));
    __ Ldrb(dbg_temp, FieldMemOperand(dbg_temp, Map::kInstanceTypeOffset));

    __ And(dbg_temp, dbg_temp,
           Operand(kStringRepresentationMask | kStringEncodingMask));
    static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
    static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
    __ Cmp(dbg_temp, Operand(encoding == String::ONE_BYTE_ENCODING
                             ? one_byte_seq_type : two_byte_seq_type));
    __ Check(eq, kUnexpectedStringType);
  }

  MemOperand operand =
      BuildSeqStringOperand(string, temp, instr->index(), encoding);
  if (encoding == String::ONE_BYTE_ENCODING) {
    __ Ldrb(result, operand);
  } else {
    __ Ldrh(result, operand);
  }
}


void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
  String::Encoding encoding = instr->hydrogen()->encoding();
  Register string = ToRegister(instr->string());
  Register value = ToRegister(instr->value());
  Register temp = ToRegister(instr->temp());

  if (FLAG_debug_code) {
    DCHECK(ToRegister(instr->context()).is(cp));
    Register index = ToRegister(instr->index());
    static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
    static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
    int encoding_mask =
        instr->hydrogen()->encoding() == String::ONE_BYTE_ENCODING
        ? one_byte_seq_type : two_byte_seq_type;
    __ EmitSeqStringSetCharCheck(string, index, kIndexIsInteger32, temp,
                                 encoding_mask);
  }
  MemOperand operand =
      BuildSeqStringOperand(string, temp, instr->index(), encoding);
  if (encoding == String::ONE_BYTE_ENCODING) {
    __ Strb(value, operand);
  } else {
    __ Strh(value, operand);
  }
}


void LCodeGen::DoSmiTag(LSmiTag* instr) {
  HChange* hchange = instr->hydrogen();
  Register input = ToRegister(instr->value());
  Register output = ToRegister(instr->result());
  if (hchange->CheckFlag(HValue::kCanOverflow) &&
      hchange->value()->CheckFlag(HValue::kUint32)) {
    DeoptimizeIfNegative(input.W(), instr, Deoptimizer::kOverflow);
  }
  __ SmiTag(output, input);
}


void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
  Register input = ToRegister(instr->value());
  Register result = ToRegister(instr->result());
  Label done, untag;

  if (instr->needs_check()) {
    DeoptimizeIfNotSmi(input, instr, Deoptimizer::kNotASmi);
  }

  __ Bind(&untag);
  __ SmiUntag(result, input);
  __ Bind(&done);
}


void LCodeGen::DoShiftI(LShiftI* instr) {
  LOperand* right_op = instr->right();
  Register left = ToRegister32(instr->left());
  Register result = ToRegister32(instr->result());

  if (right_op->IsRegister()) {
    Register right = ToRegister32(instr->right());
    switch (instr->op()) {
      case Token::ROR: __ Ror(result, left, right); break;
      case Token::SAR: __ Asr(result, left, right); break;
      case Token::SHL: __ Lsl(result, left, right); break;
      case Token::SHR:
        __ Lsr(result, left, right);
        if (instr->can_deopt()) {
          // If `left >>> right` >= 0x80000000, the result is not representable
          // in a signed 32-bit smi.
          DeoptimizeIfNegative(result, instr, Deoptimizer::kNegativeValue);
        }
        break;
      default: UNREACHABLE();
    }
  } else {
    DCHECK(right_op->IsConstantOperand());
    int shift_count = JSShiftAmountFromLConstant(right_op);
    if (shift_count == 0) {
      if ((instr->op() == Token::SHR) && instr->can_deopt()) {
        DeoptimizeIfNegative(left, instr, Deoptimizer::kNegativeValue);
      }
      __ Mov(result, left, kDiscardForSameWReg);
    } else {
      switch (instr->op()) {
        case Token::ROR: __ Ror(result, left, shift_count); break;
        case Token::SAR: __ Asr(result, left, shift_count); break;
        case Token::SHL: __ Lsl(result, left, shift_count); break;
        case Token::SHR: __ Lsr(result, left, shift_count); break;
        default: UNREACHABLE();
      }
    }
  }
}


void LCodeGen::DoShiftS(LShiftS* instr) {
  LOperand* right_op = instr->right();
  Register left = ToRegister(instr->left());
  Register result = ToRegister(instr->result());

  if (right_op->IsRegister()) {
    Register right = ToRegister(instr->right());

    // JavaScript shifts only look at the bottom 5 bits of the 'right' operand.
    // Since we're handling smis in X registers, we have to extract these bits
    // explicitly.
    __ Ubfx(result, right, kSmiShift, 5);

    switch (instr->op()) {
      case Token::ROR: {
        // This is the only case that needs a scratch register. To keep things
        // simple for the other cases, borrow a MacroAssembler scratch register.
        UseScratchRegisterScope temps(masm());
        Register temp = temps.AcquireW();
        __ SmiUntag(temp, left);
        __ Ror(result.W(), temp.W(), result.W());
        __ SmiTag(result);
        break;
      }
      case Token::SAR:
        __ Asr(result, left, result);
        __ Bic(result, result, kSmiShiftMask);
        break;
      case Token::SHL:
        __ Lsl(result, left, result);
        break;
      case Token::SHR:
        __ Lsr(result, left, result);
        __ Bic(result, result, kSmiShiftMask);
        if (instr->can_deopt()) {
          // If `left >>> right` >= 0x80000000, the result is not representable
          // in a signed 32-bit smi.
          DeoptimizeIfNegative(result, instr, Deoptimizer::kNegativeValue);
        }
        break;
      default: UNREACHABLE();
    }
  } else {
    DCHECK(right_op->IsConstantOperand());
    int shift_count = JSShiftAmountFromLConstant(right_op);
    if (shift_count == 0) {
      if ((instr->op() == Token::SHR) && instr->can_deopt()) {
        DeoptimizeIfNegative(left, instr, Deoptimizer::kNegativeValue);
      }
      __ Mov(result, left);
    } else {
      switch (instr->op()) {
        case Token::ROR:
          __ SmiUntag(result, left);
          __ Ror(result.W(), result.W(), shift_count);
          __ SmiTag(result);
          break;
        case Token::SAR:
          __ Asr(result, left, shift_count);
          __ Bic(result, result, kSmiShiftMask);
          break;
        case Token::SHL:
          __ Lsl(result, left, shift_count);
          break;
        case Token::SHR:
          __ Lsr(result, left, shift_count);
          __ Bic(result, result, kSmiShiftMask);
          break;
        default: UNREACHABLE();
      }
    }
  }
}


void LCodeGen::DoDebugBreak(LDebugBreak* instr) {
  __ Debug("LDebugBreak", 0, BREAK);
}


void LCodeGen::DoDeclareGlobals(LDeclareGlobals* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  Register scratch1 = x5;
  Register scratch2 = x6;
  DCHECK(instr->IsMarkedAsCall());

  // TODO(all): if Mov could handle object in new space then it could be used
  // here.
  __ LoadHeapObject(scratch1, instr->hydrogen()->pairs());
  __ Mov(scratch2, Smi::FromInt(instr->hydrogen()->flags()));
  __ Push(scratch1, scratch2);
  CallRuntime(Runtime::kDeclareGlobals, instr);
}


void LCodeGen::DoDeferredStackCheck(LStackCheck* instr) {
  PushSafepointRegistersScope scope(this);
  LoadContextFromDeferred(instr->context());
  __ CallRuntimeSaveDoubles(Runtime::kStackGuard);
  RecordSafepointWithLazyDeopt(
      instr, RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
  DCHECK(instr->HasEnvironment());
  LEnvironment* env = instr->environment();
  safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
}


void LCodeGen::DoStackCheck(LStackCheck* instr) {
  class DeferredStackCheck: public LDeferredCode {
   public:
    DeferredStackCheck(LCodeGen* codegen, LStackCheck* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() { codegen()->DoDeferredStackCheck(instr_); }
    virtual LInstruction* instr() { return instr_; }
   private:
    LStackCheck* instr_;
  };

  DCHECK(instr->HasEnvironment());
  LEnvironment* env = instr->environment();
  // There is no LLazyBailout instruction for stack-checks. We have to
  // prepare for lazy deoptimization explicitly here.
  if (instr->hydrogen()->is_function_entry()) {
    // Perform stack overflow check.
    Label done;
    __ CompareRoot(masm()->StackPointer(), Heap::kStackLimitRootIndex);
    __ B(hs, &done);

    PredictableCodeSizeScope predictable(masm_,
                                         Assembler::kCallSizeWithRelocation);
    DCHECK(instr->context()->IsRegister());
    DCHECK(ToRegister(instr->context()).is(cp));
    CallCode(isolate()->builtins()->StackCheck(),
             RelocInfo::CODE_TARGET,
             instr);
    __ Bind(&done);
  } else {
    DCHECK(instr->hydrogen()->is_backwards_branch());
    // Perform stack overflow check if this goto needs it before jumping.
    DeferredStackCheck* deferred_stack_check =
        new(zone()) DeferredStackCheck(this, instr);
    __ CompareRoot(masm()->StackPointer(), Heap::kStackLimitRootIndex);
    __ B(lo, deferred_stack_check->entry());

    EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
    __ Bind(instr->done_label());
    deferred_stack_check->SetExit(instr->done_label());
    RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
    // Don't record a deoptimization index for the safepoint here.
    // This will be done explicitly when emitting call and the safepoint in
    // the deferred code.
  }
}


void LCodeGen::DoStoreCodeEntry(LStoreCodeEntry* instr) {
  Register function = ToRegister(instr->function());
  Register code_object = ToRegister(instr->code_object());
  Register temp = ToRegister(instr->temp());
  __ Add(temp, code_object, Code::kHeaderSize - kHeapObjectTag);
  __ Str(temp, FieldMemOperand(function, JSFunction::kCodeEntryOffset));
}


void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
  Register context = ToRegister(instr->context());
  Register value = ToRegister(instr->value());
  Register scratch = ToRegister(instr->temp());
  MemOperand target = ContextMemOperand(context, instr->slot_index());

  Label skip_assignment;

  if (instr->hydrogen()->RequiresHoleCheck()) {
    __ Ldr(scratch, target);
    if (instr->hydrogen()->DeoptimizesOnHole()) {
      DeoptimizeIfRoot(scratch, Heap::kTheHoleValueRootIndex, instr,
                       Deoptimizer::kHole);
    } else {
      __ JumpIfNotRoot(scratch, Heap::kTheHoleValueRootIndex, &skip_assignment);
    }
  }

  __ Str(value, target);
  if (instr->hydrogen()->NeedsWriteBarrier()) {
    SmiCheck check_needed =
        instr->hydrogen()->value()->type().IsHeapObject()
            ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
    __ RecordWriteContextSlot(context, static_cast<int>(target.offset()), value,
                              scratch, GetLinkRegisterState(), kSaveFPRegs,
                              EMIT_REMEMBERED_SET, check_needed);
  }
  __ Bind(&skip_assignment);
}


void LCodeGen::DoStoreKeyedExternal(LStoreKeyedExternal* instr) {
  Register ext_ptr = ToRegister(instr->elements());
  Register key = no_reg;
  Register scratch;
  ElementsKind elements_kind = instr->elements_kind();

  bool key_is_smi = instr->hydrogen()->key()->representation().IsSmi();
  bool key_is_constant = instr->key()->IsConstantOperand();
  int constant_key = 0;
  if (key_is_constant) {
    DCHECK(instr->temp() == NULL);
    constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
    if (constant_key & 0xf0000000) {
      Abort(kArrayIndexConstantValueTooBig);
    }
  } else {
    key = ToRegister(instr->key());
    scratch = ToRegister(instr->temp());
  }

  MemOperand dst =
    PrepareKeyedExternalArrayOperand(key, ext_ptr, scratch, key_is_smi,
                                     key_is_constant, constant_key,
                                     elements_kind,
                                     instr->base_offset());

  if (elements_kind == FLOAT32_ELEMENTS) {
    DoubleRegister value = ToDoubleRegister(instr->value());
    DoubleRegister dbl_scratch = double_scratch();
    __ Fcvt(dbl_scratch.S(), value);
    __ Str(dbl_scratch.S(), dst);
  } else if (elements_kind == FLOAT64_ELEMENTS) {
    DoubleRegister value = ToDoubleRegister(instr->value());
    __ Str(value, dst);
  } else {
    Register value = ToRegister(instr->value());

    switch (elements_kind) {
      case UINT8_ELEMENTS:
      case UINT8_CLAMPED_ELEMENTS:
      case INT8_ELEMENTS:
        __ Strb(value, dst);
        break;
      case INT16_ELEMENTS:
      case UINT16_ELEMENTS:
        __ Strh(value, dst);
        break;
      case INT32_ELEMENTS:
      case UINT32_ELEMENTS:
        __ Str(value.W(), dst);
        break;
      case FLOAT32_ELEMENTS:
      case FLOAT64_ELEMENTS:
      case FAST_DOUBLE_ELEMENTS:
      case FAST_ELEMENTS:
      case FAST_SMI_ELEMENTS:
      case FAST_HOLEY_DOUBLE_ELEMENTS:
      case FAST_HOLEY_ELEMENTS:
      case FAST_HOLEY_SMI_ELEMENTS:
      case DICTIONARY_ELEMENTS:
      case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
      case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
      case FAST_STRING_WRAPPER_ELEMENTS:
      case SLOW_STRING_WRAPPER_ELEMENTS:
      case NO_ELEMENTS:
        UNREACHABLE();
        break;
    }
  }
}


void LCodeGen::DoStoreKeyedFixedDouble(LStoreKeyedFixedDouble* instr) {
  Register elements = ToRegister(instr->elements());
  DoubleRegister value = ToDoubleRegister(instr->value());
  MemOperand mem_op;

  if (instr->key()->IsConstantOperand()) {
    int constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
    if (constant_key & 0xf0000000) {
      Abort(kArrayIndexConstantValueTooBig);
    }
    int offset = instr->base_offset() + constant_key * kDoubleSize;
    mem_op = MemOperand(elements, offset);
  } else {
    Register store_base = ToRegister(instr->temp());
    Register key = ToRegister(instr->key());
    bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();
    mem_op = PrepareKeyedArrayOperand(store_base, elements, key, key_is_tagged,
                                      instr->hydrogen()->elements_kind(),
                                      instr->hydrogen()->representation(),
                                      instr->base_offset());
  }

  if (instr->NeedsCanonicalization()) {
    __ CanonicalizeNaN(double_scratch(), value);
    __ Str(double_scratch(), mem_op);
  } else {
    __ Str(value, mem_op);
  }
}


void LCodeGen::DoStoreKeyedFixed(LStoreKeyedFixed* instr) {
  Register value = ToRegister(instr->value());
  Register elements = ToRegister(instr->elements());
  Register scratch = no_reg;
  Register store_base = no_reg;
  Register key = no_reg;
  MemOperand mem_op;

  if (!instr->key()->IsConstantOperand() ||
      instr->hydrogen()->NeedsWriteBarrier()) {
    scratch = ToRegister(instr->temp());
  }

  Representation representation = instr->hydrogen()->value()->representation();
  if (instr->key()->IsConstantOperand()) {
    LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
    int offset = instr->base_offset() +
        ToInteger32(const_operand) * kPointerSize;
    store_base = elements;
    if (representation.IsInteger32()) {
      DCHECK(instr->hydrogen()->store_mode() == STORE_TO_INITIALIZED_ENTRY);
      DCHECK(instr->hydrogen()->elements_kind() == FAST_SMI_ELEMENTS);
      STATIC_ASSERT(static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits);
      STATIC_ASSERT(kSmiTag == 0);
      mem_op = UntagSmiMemOperand(store_base, offset);
    } else {
      mem_op = MemOperand(store_base, offset);
    }
  } else {
    store_base = scratch;
    key = ToRegister(instr->key());
    bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();

    mem_op = PrepareKeyedArrayOperand(store_base, elements, key, key_is_tagged,
                                      instr->hydrogen()->elements_kind(),
                                      representation, instr->base_offset());
  }

  __ Store(value, mem_op, representation);

  if (instr->hydrogen()->NeedsWriteBarrier()) {
    DCHECK(representation.IsTagged());
    // This assignment may cause element_addr to alias store_base.
    Register element_addr = scratch;
    SmiCheck check_needed =
        instr->hydrogen()->value()->type().IsHeapObject()
            ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
    // Compute address of modified element and store it into key register.
    __ Add(element_addr, mem_op.base(), mem_op.OffsetAsOperand());
    __ RecordWrite(elements, element_addr, value, GetLinkRegisterState(),
                   kSaveFPRegs, EMIT_REMEMBERED_SET, check_needed,
                   instr->hydrogen()->PointersToHereCheckForValue());
  }
}


void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->object()).is(StoreDescriptor::ReceiverRegister()));
  DCHECK(ToRegister(instr->key()).is(StoreDescriptor::NameRegister()));
  DCHECK(ToRegister(instr->value()).is(StoreDescriptor::ValueRegister()));

  EmitVectorStoreICRegisters<LStoreKeyedGeneric>(instr);

  Handle<Code> ic = CodeFactory::KeyedStoreICInOptimizedCode(
                        isolate(), instr->language_mode())
                        .code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);
}


void LCodeGen::DoMaybeGrowElements(LMaybeGrowElements* instr) {
  class DeferredMaybeGrowElements final : public LDeferredCode {
   public:
    DeferredMaybeGrowElements(LCodeGen* codegen, LMaybeGrowElements* instr)
        : LDeferredCode(codegen), instr_(instr) {}
    void Generate() override { codegen()->DoDeferredMaybeGrowElements(instr_); }
    LInstruction* instr() override { return instr_; }

   private:
    LMaybeGrowElements* instr_;
  };

  Register result = x0;
  DeferredMaybeGrowElements* deferred =
      new (zone()) DeferredMaybeGrowElements(this, instr);
  LOperand* key = instr->key();
  LOperand* current_capacity = instr->current_capacity();

  DCHECK(instr->hydrogen()->key()->representation().IsInteger32());
  DCHECK(instr->hydrogen()->current_capacity()->representation().IsInteger32());
  DCHECK(key->IsConstantOperand() || key->IsRegister());
  DCHECK(current_capacity->IsConstantOperand() ||
         current_capacity->IsRegister());

  if (key->IsConstantOperand() && current_capacity->IsConstantOperand()) {
    int32_t constant_key = ToInteger32(LConstantOperand::cast(key));
    int32_t constant_capacity =
        ToInteger32(LConstantOperand::cast(current_capacity));
    if (constant_key >= constant_capacity) {
      // Deferred case.
      __ B(deferred->entry());
    }
  } else if (key->IsConstantOperand()) {
    int32_t constant_key = ToInteger32(LConstantOperand::cast(key));
    __ Cmp(ToRegister(current_capacity), Operand(constant_key));
    __ B(le, deferred->entry());
  } else if (current_capacity->IsConstantOperand()) {
    int32_t constant_capacity =
        ToInteger32(LConstantOperand::cast(current_capacity));
    __ Cmp(ToRegister(key), Operand(constant_capacity));
    __ B(ge, deferred->entry());
  } else {
    __ Cmp(ToRegister(key), ToRegister(current_capacity));
    __ B(ge, deferred->entry());
  }

  __ Mov(result, ToRegister(instr->elements()));

  __ Bind(deferred->exit());
}


void LCodeGen::DoDeferredMaybeGrowElements(LMaybeGrowElements* instr) {
  // TODO(3095996): Get rid of this. For now, we need to make the
  // result register contain a valid pointer because it is already
  // contained in the register pointer map.
  Register result = x0;
  __ Mov(result, 0);

  // We have to call a stub.
  {
    PushSafepointRegistersScope scope(this);
    __ Move(result, ToRegister(instr->object()));

    LOperand* key = instr->key();
    if (key->IsConstantOperand()) {
      __ Mov(x3, Operand(ToSmi(LConstantOperand::cast(key))));
    } else {
      __ Mov(x3, ToRegister(key));
      __ SmiTag(x3);
    }

    GrowArrayElementsStub stub(isolate(), instr->hydrogen()->is_js_array(),
                               instr->hydrogen()->kind());
    __ CallStub(&stub);
    RecordSafepointWithLazyDeopt(
        instr, RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
    __ StoreToSafepointRegisterSlot(result, result);
  }

  // Deopt on smi, which means the elements array changed to dictionary mode.
  DeoptimizeIfSmi(result, instr, Deoptimizer::kSmi);
}


void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
  Representation representation = instr->representation();

  Register object = ToRegister(instr->object());
  HObjectAccess access = instr->hydrogen()->access();
  int offset = access.offset();

  if (access.IsExternalMemory()) {
    DCHECK(!instr->hydrogen()->has_transition());
    DCHECK(!instr->hydrogen()->NeedsWriteBarrier());
    Register value = ToRegister(instr->value());
    __ Store(value, MemOperand(object, offset), representation);
    return;
  }

  __ AssertNotSmi(object);

  if (!FLAG_unbox_double_fields && representation.IsDouble()) {
    DCHECK(access.IsInobject());
    DCHECK(!instr->hydrogen()->has_transition());
    DCHECK(!instr->hydrogen()->NeedsWriteBarrier());
    FPRegister value = ToDoubleRegister(instr->value());
    __ Str(value, FieldMemOperand(object, offset));
    return;
  }

  DCHECK(!representation.IsSmi() ||
         !instr->value()->IsConstantOperand() ||
         IsInteger32Constant(LConstantOperand::cast(instr->value())));

  if (instr->hydrogen()->has_transition()) {
    Handle<Map> transition = instr->hydrogen()->transition_map();
    AddDeprecationDependency(transition);
    // Store the new map value.
    Register new_map_value = ToRegister(instr->temp0());
    __ Mov(new_map_value, Operand(transition));
    __ Str(new_map_value, FieldMemOperand(object, HeapObject::kMapOffset));
    if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
      // Update the write barrier for the map field.
      __ RecordWriteForMap(object,
                           new_map_value,
                           ToRegister(instr->temp1()),
                           GetLinkRegisterState(),
                           kSaveFPRegs);
    }
  }

  // Do the store.
  Register destination;
  if (access.IsInobject()) {
    destination = object;
  } else {
    Register temp0 = ToRegister(instr->temp0());
    __ Ldr(temp0, FieldMemOperand(object, JSObject::kPropertiesOffset));
    destination = temp0;
  }

  if (FLAG_unbox_double_fields && representation.IsDouble()) {
    DCHECK(access.IsInobject());
    FPRegister value = ToDoubleRegister(instr->value());
    __ Str(value, FieldMemOperand(object, offset));
  } else if (representation.IsSmi() &&
             instr->hydrogen()->value()->representation().IsInteger32()) {
    DCHECK(instr->hydrogen()->store_mode() == STORE_TO_INITIALIZED_ENTRY);
#ifdef DEBUG
    Register temp0 = ToRegister(instr->temp0());
    __ Ldr(temp0, FieldMemOperand(destination, offset));
    __ AssertSmi(temp0);
    // If destination aliased temp0, restore it to the address calculated
    // earlier.
    if (destination.Is(temp0)) {
      DCHECK(!access.IsInobject());
      __ Ldr(destination, FieldMemOperand(object, JSObject::kPropertiesOffset));
    }
#endif
    STATIC_ASSERT(static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits);
    STATIC_ASSERT(kSmiTag == 0);
    Register value = ToRegister(instr->value());
    __ Store(value, UntagSmiFieldMemOperand(destination, offset),
             Representation::Integer32());
  } else {
    Register value = ToRegister(instr->value());
    __ Store(value, FieldMemOperand(destination, offset), representation);
  }
  if (instr->hydrogen()->NeedsWriteBarrier()) {
    Register value = ToRegister(instr->value());
    __ RecordWriteField(destination,
                        offset,
                        value,                        // Clobbered.
                        ToRegister(instr->temp1()),   // Clobbered.
                        GetLinkRegisterState(),
                        kSaveFPRegs,
                        EMIT_REMEMBERED_SET,
                        instr->hydrogen()->SmiCheckForWriteBarrier(),
                        instr->hydrogen()->PointersToHereCheckForValue());
  }
}


void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->object()).is(StoreDescriptor::ReceiverRegister()));
  DCHECK(ToRegister(instr->value()).is(StoreDescriptor::ValueRegister()));

  EmitVectorStoreICRegisters<LStoreNamedGeneric>(instr);

  __ Mov(StoreDescriptor::NameRegister(), Operand(instr->name()));
  Handle<Code> ic =
      CodeFactory::StoreICInOptimizedCode(isolate(), instr->language_mode())
          .code();
  CallCode(ic, RelocInfo::CODE_TARGET, instr);
}


void LCodeGen::DoStringAdd(LStringAdd* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->left()).Is(x1));
  DCHECK(ToRegister(instr->right()).Is(x0));
  StringAddStub stub(isolate(),
                     instr->hydrogen()->flags(),
                     instr->hydrogen()->pretenure_flag());
  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
}


void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
  class DeferredStringCharCodeAt: public LDeferredCode {
   public:
    DeferredStringCharCodeAt(LCodeGen* codegen, LStringCharCodeAt* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() { codegen()->DoDeferredStringCharCodeAt(instr_); }
    virtual LInstruction* instr() { return instr_; }
   private:
    LStringCharCodeAt* instr_;
  };

  DeferredStringCharCodeAt* deferred =
      new(zone()) DeferredStringCharCodeAt(this, instr);

  StringCharLoadGenerator::Generate(masm(),
                                    ToRegister(instr->string()),
                                    ToRegister32(instr->index()),
                                    ToRegister(instr->result()),
                                    deferred->entry());
  __ Bind(deferred->exit());
}


void LCodeGen::DoDeferredStringCharCodeAt(LStringCharCodeAt* instr) {
  Register string = ToRegister(instr->string());
  Register result = ToRegister(instr->result());

  // TODO(3095996): Get rid of this. For now, we need to make the
  // result register contain a valid pointer because it is already
  // contained in the register pointer map.
  __ Mov(result, 0);

  PushSafepointRegistersScope scope(this);
  __ Push(string);
  // Push the index as a smi. This is safe because of the checks in
  // DoStringCharCodeAt above.
  Register index = ToRegister(instr->index());
  __ SmiTagAndPush(index);

  CallRuntimeFromDeferred(Runtime::kStringCharCodeAtRT, 2, instr,
                          instr->context());
  __ AssertSmi(x0);
  __ SmiUntag(x0);
  __ StoreToSafepointRegisterSlot(x0, result);
}


void LCodeGen::DoStringCharFromCode(LStringCharFromCode* instr) {
  class DeferredStringCharFromCode: public LDeferredCode {
   public:
    DeferredStringCharFromCode(LCodeGen* codegen, LStringCharFromCode* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() { codegen()->DoDeferredStringCharFromCode(instr_); }
    virtual LInstruction* instr() { return instr_; }
   private:
    LStringCharFromCode* instr_;
  };

  DeferredStringCharFromCode* deferred =
      new(zone()) DeferredStringCharFromCode(this, instr);

  DCHECK(instr->hydrogen()->value()->representation().IsInteger32());
  Register char_code = ToRegister32(instr->char_code());
  Register result = ToRegister(instr->result());

  __ Cmp(char_code, String::kMaxOneByteCharCode);
  __ B(hi, deferred->entry());
  __ LoadRoot(result, Heap::kSingleCharacterStringCacheRootIndex);
  __ Add(result, result, FixedArray::kHeaderSize - kHeapObjectTag);
  __ Ldr(result, MemOperand(result, char_code, SXTW, kPointerSizeLog2));
  __ CompareRoot(result, Heap::kUndefinedValueRootIndex);
  __ B(eq, deferred->entry());
  __ Bind(deferred->exit());
}


void LCodeGen::DoDeferredStringCharFromCode(LStringCharFromCode* instr) {
  Register char_code = ToRegister(instr->char_code());
  Register result = ToRegister(instr->result());

  // TODO(3095996): Get rid of this. For now, we need to make the
  // result register contain a valid pointer because it is already
  // contained in the register pointer map.
  __ Mov(result, 0);

  PushSafepointRegistersScope scope(this);
  __ SmiTagAndPush(char_code);
  CallRuntimeFromDeferred(Runtime::kStringCharFromCode, 1, instr,
                          instr->context());
  __ StoreToSafepointRegisterSlot(x0, result);
}


void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
  DCHECK(ToRegister(instr->context()).is(cp));
  DCHECK(ToRegister(instr->left()).is(x1));
  DCHECK(ToRegister(instr->right()).is(x0));

  Handle<Code> code = CodeFactory::StringCompare(isolate(), instr->op()).code();
  CallCode(code, RelocInfo::CODE_TARGET, instr);
  __ CompareRoot(x0, Heap::kTrueValueRootIndex);
  EmitBranch(instr, eq);
}


void LCodeGen::DoSubI(LSubI* instr) {
  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  Register result = ToRegister32(instr->result());
  Register left = ToRegister32(instr->left());
  Operand right = ToShiftedRightOperand32(instr->right(), instr);

  if (can_overflow) {
    __ Subs(result, left, right);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  } else {
    __ Sub(result, left, right);
  }
}


void LCodeGen::DoSubS(LSubS* instr) {
  bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
  Register result = ToRegister(instr->result());
  Register left = ToRegister(instr->left());
  Operand right = ToOperand(instr->right());
  if (can_overflow) {
    __ Subs(result, left, right);
    DeoptimizeIf(vs, instr, Deoptimizer::kOverflow);
  } else {
    __ Sub(result, left, right);
  }
}


void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr,
                                   LOperand* value,
                                   LOperand* temp1,
                                   LOperand* temp2) {
  Register input = ToRegister(value);
  Register scratch1 = ToRegister(temp1);
  DoubleRegister dbl_scratch1 = double_scratch();

  Label done;

  if (instr->truncating()) {
    Register output = ToRegister(instr->result());
    Label check_bools;

    // If it's not a heap number, jump to undefined check.
    __ JumpIfNotHeapNumber(input, &check_bools);

    // A heap number: load value and convert to int32 using truncating function.
    __ TruncateHeapNumberToI(output, input);
    __ B(&done);

    __ Bind(&check_bools);

    Register true_root = output;
    Register false_root = scratch1;
    __ LoadTrueFalseRoots(true_root, false_root);
    __ Cmp(input, true_root);
    __ Cset(output, eq);
    __ Ccmp(input, false_root, ZFlag, ne);
    __ B(eq, &done);

    // Output contains zero, undefined is converted to zero for truncating
    // conversions.
    DeoptimizeIfNotRoot(input, Heap::kUndefinedValueRootIndex, instr,
                        Deoptimizer::kNotAHeapNumberUndefinedBoolean);
  } else {
    Register output = ToRegister32(instr->result());
    DoubleRegister dbl_scratch2 = ToDoubleRegister(temp2);

    DeoptimizeIfNotHeapNumber(input, instr);

    // A heap number: load value and convert to int32 using non-truncating
    // function. If the result is out of range, branch to deoptimize.
    __ Ldr(dbl_scratch1, FieldMemOperand(input, HeapNumber::kValueOffset));
    __ TryRepresentDoubleAsInt32(output, dbl_scratch1, dbl_scratch2);
    DeoptimizeIf(ne, instr, Deoptimizer::kLostPrecisionOrNaN);

    if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
      __ Cmp(output, 0);
      __ B(ne, &done);
      __ Fmov(scratch1, dbl_scratch1);
      DeoptimizeIfNegative(scratch1, instr, Deoptimizer::kMinusZero);
    }
  }
  __ Bind(&done);
}


void LCodeGen::DoTaggedToI(LTaggedToI* instr) {
  class DeferredTaggedToI: public LDeferredCode {
   public:
    DeferredTaggedToI(LCodeGen* codegen, LTaggedToI* instr)
        : LDeferredCode(codegen), instr_(instr) { }
    virtual void Generate() {
      codegen()->DoDeferredTaggedToI(instr_, instr_->value(), instr_->temp1(),
                                     instr_->temp2());
    }

    virtual LInstruction* instr() { return instr_; }
   private:
    LTaggedToI* instr_;
  };

  Register input = ToRegister(instr->value());
  Register output = ToRegister(instr->result());

  if (instr->hydrogen()->value()->representation().IsSmi()) {
    __ SmiUntag(output, input);
  } else {
    DeferredTaggedToI* deferred = new(zone()) DeferredTaggedToI(this, instr);

    __ JumpIfNotSmi(input, deferred->entry());
    __ SmiUntag(output, input);
    __ Bind(deferred->exit());
  }
}


void LCodeGen::DoThisFunction(LThisFunction* instr) {
  Register result = ToRegister(instr->result());
  __ Ldr(result, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
}


void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
  Register object = ToRegister(instr->object());

  Handle<Map> from_map = instr->original_map();
  Handle<Map> to_map = instr->transitioned_map();
  ElementsKind from_kind = instr->from_kind();
  ElementsKind to_kind = instr->to_kind();

  Label not_applicable;

  if (IsSimpleMapChangeTransition(from_kind, to_kind)) {
    Register temp1 = ToRegister(instr->temp1());
    Register new_map = ToRegister(instr->temp2());
    __ CheckMap(object, temp1, from_map, &not_applicable, DONT_DO_SMI_CHECK);
    __ Mov(new_map, Operand(to_map));
    __ Str(new_map, FieldMemOperand(object, HeapObject::kMapOffset));
    // Write barrier.
    __ RecordWriteForMap(object, new_map, temp1, GetLinkRegisterState(),
                         kDontSaveFPRegs);
  } else {
    {
      UseScratchRegisterScope temps(masm());
      // Use the temp register only in a restricted scope - the codegen checks
      // that we do not use any register across a call.
      __ CheckMap(object, temps.AcquireX(), from_map, &not_applicable,
                  DONT_DO_SMI_CHECK);
    }
    DCHECK(object.is(x0));
    DCHECK(ToRegister(instr->context()).is(cp));
    PushSafepointRegistersScope scope(this);
    __ Mov(x1, Operand(to_map));
    TransitionElementsKindStub stub(isolate(), from_kind, to_kind);
    __ CallStub(&stub);
    RecordSafepointWithRegisters(
        instr->pointer_map(), 0, Safepoint::kLazyDeopt);
  }
  __ Bind(&not_applicable);
}


void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
  Register object = ToRegister(instr->object());
  Register temp1 = ToRegister(instr->temp1());
  Register temp2 = ToRegister(instr->temp2());

  Label no_memento_found;
  __ TestJSArrayForAllocationMemento(object, temp1, temp2, &no_memento_found);
  DeoptimizeIf(eq, instr, Deoptimizer::kMementoFound);
  __ Bind(&no_memento_found);
}


void LCodeGen::DoTruncateDoubleToIntOrSmi(LTruncateDoubleToIntOrSmi* instr) {
  DoubleRegister input = ToDoubleRegister(instr->value());
  Register result = ToRegister(instr->result());
  __ TruncateDoubleToI(result, input);
  if (instr->tag_result()) {
    __ SmiTag(result, result);
  }
}


void LCodeGen::DoTypeof(LTypeof* instr) {
  DCHECK(ToRegister(instr->value()).is(x3));
  DCHECK(ToRegister(instr->result()).is(x0));
  Label end, do_call;
  Register value_register = ToRegister(instr->value());
  __ JumpIfNotSmi(value_register, &do_call);
  __ Mov(x0, Immediate(isolate()->factory()->number_string()));
  __ B(&end);
  __ Bind(&do_call);
  TypeofStub stub(isolate());
  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  __ Bind(&end);
}


void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
  Handle<String> type_name = instr->type_literal();
  Label* true_label = instr->TrueLabel(chunk_);
  Label* false_label = instr->FalseLabel(chunk_);
  Register value = ToRegister(instr->value());

  Factory* factory = isolate()->factory();
  if (String::Equals(type_name, factory->number_string())) {
    __ JumpIfSmi(value, true_label);

    int true_block = instr->TrueDestination(chunk_);
    int false_block = instr->FalseDestination(chunk_);
    int next_block = GetNextEmittedBlock();

    if (true_block == false_block) {
      EmitGoto(true_block);
    } else if (true_block == next_block) {
      __ JumpIfNotHeapNumber(value, chunk_->GetAssemblyLabel(false_block));
    } else {
      __ JumpIfHeapNumber(value, chunk_->GetAssemblyLabel(true_block));
      if (false_block != next_block) {
        __ B(chunk_->GetAssemblyLabel(false_block));
      }
    }

  } else if (String::Equals(type_name, factory->string_string())) {
    DCHECK((instr->temp1() != NULL) && (instr->temp2() != NULL));
    Register map = ToRegister(instr->temp1());
    Register scratch = ToRegister(instr->temp2());

    __ JumpIfSmi(value, false_label);
    __ CompareObjectType(value, map, scratch, FIRST_NONSTRING_TYPE);
    EmitBranch(instr, lt);

  } else if (String::Equals(type_name, factory->symbol_string())) {
    DCHECK((instr->temp1() != NULL) && (instr->temp2() != NULL));
    Register map = ToRegister(instr->temp1());
    Register scratch = ToRegister(instr->temp2());

    __ JumpIfSmi(value, false_label);
    __ CompareObjectType(value, map, scratch, SYMBOL_TYPE);
    EmitBranch(instr, eq);

  } else if (String::Equals(type_name, factory->boolean_string())) {
    __ JumpIfRoot(value, Heap::kTrueValueRootIndex, true_label);
    __ CompareRoot(value, Heap::kFalseValueRootIndex);
    EmitBranch(instr, eq);

  } else if (String::Equals(type_name, factory->undefined_string())) {
    DCHECK(instr->temp1() != NULL);
    Register scratch = ToRegister(instr->temp1());

    __ JumpIfRoot(value, Heap::kNullValueRootIndex, false_label);
    __ JumpIfSmi(value, false_label);
    // Check for undetectable objects and jump to the true branch in this case.
    __ Ldr(scratch, FieldMemOperand(value, HeapObject::kMapOffset));
    __ Ldrb(scratch, FieldMemOperand(scratch, Map::kBitFieldOffset));
    EmitTestAndBranch(instr, ne, scratch, 1 << Map::kIsUndetectable);

  } else if (String::Equals(type_name, factory->function_string())) {
    DCHECK(instr->temp1() != NULL);
    Register scratch = ToRegister(instr->temp1());

    __ JumpIfSmi(value, false_label);
    __ Ldr(scratch, FieldMemOperand(value, HeapObject::kMapOffset));
    __ Ldrb(scratch, FieldMemOperand(scratch, Map::kBitFieldOffset));
    __ And(scratch, scratch,
           (1 << Map::kIsCallable) | (1 << Map::kIsUndetectable));
    EmitCompareAndBranch(instr, eq, scratch, 1 << Map::kIsCallable);

  } else if (String::Equals(type_name, factory->object_string())) {
    DCHECK((instr->temp1() != NULL) && (instr->temp2() != NULL));
    Register map = ToRegister(instr->temp1());
    Register scratch = ToRegister(instr->temp2());

    __ JumpIfSmi(value, false_label);
    __ JumpIfRoot(value, Heap::kNullValueRootIndex, true_label);
    STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
    __ JumpIfObjectType(value, map, scratch, FIRST_JS_RECEIVER_TYPE,
                        false_label, lt);
    // Check for callable or undetectable objects => false.
    __ Ldrb(scratch, FieldMemOperand(map, Map::kBitFieldOffset));
    EmitTestAndBranch(instr, eq, scratch,
                      (1 << Map::kIsCallable) | (1 << Map::kIsUndetectable));

// clang-format off
#define SIMD128_TYPE(TYPE, Type, type, lane_count, lane_type)       \
  } else if (String::Equals(type_name, factory->type##_string())) { \
    DCHECK((instr->temp1() != NULL) && (instr->temp2() != NULL));   \
    Register map = ToRegister(instr->temp1());                      \
                                                                    \
    __ JumpIfSmi(value, false_label);                               \
    __ Ldr(map, FieldMemOperand(value, HeapObject::kMapOffset));    \
    __ CompareRoot(map, Heap::k##Type##MapRootIndex);               \
    EmitBranch(instr, eq);
  SIMD128_TYPES(SIMD128_TYPE)
#undef SIMD128_TYPE
    // clang-format on

  } else {
    __ B(false_label);
  }
}


void LCodeGen::DoUint32ToDouble(LUint32ToDouble* instr) {
  __ Ucvtf(ToDoubleRegister(instr->result()), ToRegister32(instr->value()));
}


void LCodeGen::DoCheckMapValue(LCheckMapValue* instr) {
  Register object = ToRegister(instr->value());
  Register map = ToRegister(instr->map());
  Register temp = ToRegister(instr->temp());
  __ Ldr(temp, FieldMemOperand(object, HeapObject::kMapOffset));
  __ Cmp(map, temp);
  DeoptimizeIf(ne, instr, Deoptimizer::kWrongMap);
}


void LCodeGen::DoWrapReceiver(LWrapReceiver* instr) {
  Register receiver = ToRegister(instr->receiver());
  Register function = ToRegister(instr->function());
  Register result = ToRegister(instr->result());

  // If the receiver is null or undefined, we have to pass the global object as
  // a receiver to normal functions. Values have to be passed unchanged to
  // builtins and strict-mode functions.
  Label global_object, done, copy_receiver;

  if (!instr->hydrogen()->known_function()) {
    __ Ldr(result, FieldMemOperand(function,
                                   JSFunction::kSharedFunctionInfoOffset));

    // CompilerHints is an int32 field. See objects.h.
    __ Ldr(result.W(),
           FieldMemOperand(result, SharedFunctionInfo::kCompilerHintsOffset));

    // Do not transform the receiver to object for strict mode functions.
    __ Tbnz(result, SharedFunctionInfo::kStrictModeFunction, &copy_receiver);

    // Do not transform the receiver to object for builtins.
    __ Tbnz(result, SharedFunctionInfo::kNative, &copy_receiver);
  }

  // Normal function. Replace undefined or null with global receiver.
  __ JumpIfRoot(receiver, Heap::kNullValueRootIndex, &global_object);
  __ JumpIfRoot(receiver, Heap::kUndefinedValueRootIndex, &global_object);

  // Deoptimize if the receiver is not a JS object.
  DeoptimizeIfSmi(receiver, instr, Deoptimizer::kSmi);
  __ CompareObjectType(receiver, result, result, FIRST_JS_RECEIVER_TYPE);
  __ B(ge, &copy_receiver);
  Deoptimize(instr, Deoptimizer::kNotAJavaScriptObject);

  __ Bind(&global_object);
  __ Ldr(result, FieldMemOperand(function, JSFunction::kContextOffset));
  __ Ldr(result, ContextMemOperand(result, Context::NATIVE_CONTEXT_INDEX));
  __ Ldr(result, ContextMemOperand(result, Context::GLOBAL_PROXY_INDEX));
  __ B(&done);

  __ Bind(&copy_receiver);
  __ Mov(result, receiver);
  __ Bind(&done);
}


void LCodeGen::DoDeferredLoadMutableDouble(LLoadFieldByIndex* instr,
                                           Register result,
                                           Register object,
                                           Register index) {
  PushSafepointRegistersScope scope(this);
  __ Push(object);
  __ Push(index);
  __ Mov(cp, 0);
  __ CallRuntimeSaveDoubles(Runtime::kLoadMutableDouble);
  RecordSafepointWithRegisters(
      instr->pointer_map(), 2, Safepoint::kNoLazyDeopt);
  __ StoreToSafepointRegisterSlot(x0, result);
}


void LCodeGen::DoLoadFieldByIndex(LLoadFieldByIndex* instr) {
  class DeferredLoadMutableDouble final : public LDeferredCode {
   public:
    DeferredLoadMutableDouble(LCodeGen* codegen,
                              LLoadFieldByIndex* instr,
                              Register result,
                              Register object,
                              Register index)
        : LDeferredCode(codegen),
          instr_(instr),
          result_(result),
          object_(object),
          index_(index) {
    }
    void Generate() override {
      codegen()->DoDeferredLoadMutableDouble(instr_, result_, object_, index_);
    }
    LInstruction* instr() override { return instr_; }

   private:
    LLoadFieldByIndex* instr_;
    Register result_;
    Register object_;
    Register index_;
  };
  Register object = ToRegister(instr->object());
  Register index = ToRegister(instr->index());
  Register result = ToRegister(instr->result());

  __ AssertSmi(index);

  DeferredLoadMutableDouble* deferred;
  deferred = new(zone()) DeferredLoadMutableDouble(
      this, instr, result, object, index);

  Label out_of_object, done;

  __ TestAndBranchIfAnySet(
      index, reinterpret_cast<uint64_t>(Smi::FromInt(1)), deferred->entry());
  __ Mov(index, Operand(index, ASR, 1));

  __ Cmp(index, Smi::FromInt(0));
  __ B(lt, &out_of_object);

  STATIC_ASSERT(kPointerSizeLog2 > kSmiTagSize);
  __ Add(result, object, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
  __ Ldr(result, FieldMemOperand(result, JSObject::kHeaderSize));

  __ B(&done);

  __ Bind(&out_of_object);
  __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
  // Index is equal to negated out of object property index plus 1.
  __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
  __ Ldr(result, FieldMemOperand(result,
                                 FixedArray::kHeaderSize - kPointerSize));
  __ Bind(deferred->exit());
  __ Bind(&done);
}

}  // namespace internal
}  // namespace v8