text: // Copyright 2012 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 "v8.h"
  
  #if V8_TARGET_ARCH_IA32
  
  #include "ia32/lithium-codegen-ia32.h"
  #include "ic.h"
  #include "code-stubs.h"
  #include "deoptimizer.h"
  #include "stub-cache.h"
  #include "codegen.h"
  #include "hydrogen-osr.h"
  
  namespace v8 {
  namespace internal {
  
  
  static SaveFPRegsMode GetSaveFPRegsMode(Isolate* isolate) {
    // We don't need to save floating point regs when generating the snapshot
    return CpuFeatures::IsSafeForSnapshot(isolate, SSE2) ? kSaveFPRegs
                                                         : kDontSaveFPRegs;
  }
  
  
  // When invoking builtins, we need to record the safepoint in the middle of
  // the invoke instruction sequence generated by the macro assembler.
  class SafepointGenerator V8_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 V8_OVERRIDE {}
  
    virtual void AfterCall() const V8_OVERRIDE {
      codegen_->RecordSafepoint(pointers_, deopt_mode_);
    }
  
   private:
    LCodeGen* codegen_;
    LPointerMap* pointers_;
    Safepoint::DeoptMode deopt_mode_;
  };
  
  
  #define __ masm()->
  
  bool LCodeGen::GenerateCode() {
    LPhase phase("Z_Code generation", chunk());
    ASSERT(is_unused());
    status_ = GENERATING;
  
    // Open a frame scope to indicate that there is a frame on the stack.  The
    // MANUAL indicates that the scope shouldn't actually generate code to set up
    // the frame (that is done in GeneratePrologue).
    FrameScope frame_scope(masm_, StackFrame::MANUAL);
  
    support_aligned_spilled_doubles_ = info()->IsOptimizing();
  
    dynamic_frame_alignment_ = info()->IsOptimizing() &&
        ((chunk()->num_double_slots() > 2 &&
          !chunk()->graph()->is_recursive()) ||
         !info()->osr_ast_id().IsNone());
  
    return GeneratePrologue() &&
        GenerateBody() &&
        GenerateDeferredCode() &&
        GenerateJumpTable() &&
        GenerateSafepointTable();
  }
  
  
  void LCodeGen::FinishCode(Handle<Code> code) {
    ASSERT(is_done());
    code->set_stack_slots(GetStackSlotCount());
    code->set_safepoint_table_offset(safepoints_.GetCodeOffset());
    if (code->is_optimized_code()) RegisterWeakObjectsInOptimizedCode(code);
    PopulateDeoptimizationData(code);
    if (!info()->IsStub()) {
      Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(code);
    }
  }
  
  
  #ifdef _MSC_VER
  void LCodeGen::MakeSureStackPagesMapped(int offset) {
    const int kPageSize = 4 * KB;
    for (offset -= kPageSize; offset > 0; offset -= kPageSize) {
      __ mov(Operand(esp, offset), eax);
    }
  }
  #endif
  
  
  void LCodeGen::SaveCallerDoubles() {
    ASSERT(info()->saves_caller_doubles());
    ASSERT(NeedsEagerFrame());
    Comment(";;; Save clobbered callee double registers");
    CpuFeatureScope scope(masm(), SSE2);
    int count = 0;
    BitVector* doubles = chunk()->allocated_double_registers();
    BitVector::Iterator save_iterator(doubles);
    while (!save_iterator.Done()) {
      __ movsd(MemOperand(esp, count * kDoubleSize),
                XMMRegister::FromAllocationIndex(save_iterator.Current()));
      save_iterator.Advance();
      count++;
    }
  }
  
  
  void LCodeGen::RestoreCallerDoubles() {
    ASSERT(info()->saves_caller_doubles());
    ASSERT(NeedsEagerFrame());
    Comment(";;; Restore clobbered callee double registers");
    CpuFeatureScope scope(masm(), SSE2);
    BitVector* doubles = chunk()->allocated_double_registers();
    BitVector::Iterator save_iterator(doubles);
    int count = 0;
    while (!save_iterator.Done()) {
      __ movsd(XMMRegister::FromAllocationIndex(save_iterator.Current()),
                MemOperand(esp, count * kDoubleSize));
      save_iterator.Advance();
      count++;
    }
  }
  
  
  bool LCodeGen::GeneratePrologue() {
    ASSERT(is_generating());
  
    if (info()->IsOptimizing()) {
      ProfileEntryHookStub::MaybeCallEntryHook(masm_);
  
  #ifdef DEBUG
      if (strlen(FLAG_stop_at) > 0 &&
          info_->function()->name()->IsUtf8EqualTo(CStrVector(FLAG_stop_at))) {
        __ int3();
      }
  #endif
  
      // Sloppy mode functions and builtins need to replace the receiver with the
      // global proxy when called as functions (without an explicit receiver
      // object).
      if (info_->this_has_uses() &&
          info_->strict_mode() == SLOPPY &&
          !info_->is_native()) {
        Label ok;
        // +1 for return address.
        int receiver_offset = (scope()->num_parameters() + 1) * kPointerSize;
        __ mov(ecx, Operand(esp, receiver_offset));
  
        __ cmp(ecx, isolate()->factory()->undefined_value());
        __ j(not_equal, &ok, Label::kNear);
  
        __ mov(ecx, GlobalObjectOperand());
        __ mov(ecx, FieldOperand(ecx, GlobalObject::kGlobalReceiverOffset));
  
        __ mov(Operand(esp, receiver_offset), ecx);
  
        __ bind(&ok);
      }
  
      if (support_aligned_spilled_doubles_ && dynamic_frame_alignment_) {
        // Move state of dynamic frame alignment into edx.
        __ Move(edx, Immediate(kNoAlignmentPadding));
  
        Label do_not_pad, align_loop;
        STATIC_ASSERT(kDoubleSize == 2 * kPointerSize);
        // Align esp + 4 to a multiple of 2 * kPointerSize.
        __ test(esp, Immediate(kPointerSize));
        __ j(not_zero, &do_not_pad, Label::kNear);
        __ push(Immediate(0));
        __ mov(ebx, esp);
        __ mov(edx, Immediate(kAlignmentPaddingPushed));
        // Copy arguments, receiver, and return address.
        __ mov(ecx, Immediate(scope()->num_parameters() + 2));
  
        __ bind(&align_loop);
        __ mov(eax, Operand(ebx, 1 * kPointerSize));
        __ mov(Operand(ebx, 0), eax);
        __ add(Operand(ebx), Immediate(kPointerSize));
        __ dec(ecx);
        __ j(not_zero, &align_loop, Label::kNear);
        __ mov(Operand(ebx, 0), Immediate(kAlignmentZapValue));
        __ bind(&do_not_pad);
      }
    }
  
    info()->set_prologue_offset(masm_->pc_offset());
    if (NeedsEagerFrame()) {
      ASSERT(!frame_is_built_);
      frame_is_built_ = true;
      __ Prologue(info()->IsStub() ? BUILD_STUB_FRAME : BUILD_FUNCTION_FRAME);
      info()->AddNoFrameRange(0, masm_->pc_offset());
    }
  
    if (info()->IsOptimizing() &&
        dynamic_frame_alignment_ &&
        FLAG_debug_code) {
      __ test(esp, Immediate(kPointerSize));
      __ Assert(zero, kFrameIsExpectedToBeAligned);
    }
  
    // Reserve space for the stack slots needed by the code.
    int slots = GetStackSlotCount();
    ASSERT(slots != 0 || !info()->IsOptimizing());
    if (slots > 0) {
      if (slots == 1) {
        if (dynamic_frame_alignment_) {
          __ push(edx);
        } else {
          __ push(Immediate(kNoAlignmentPadding));
        }
      } else {
        if (FLAG_debug_code) {
          __ sub(Operand(esp), Immediate(slots * kPointerSize));
  #ifdef _MSC_VER
          MakeSureStackPagesMapped(slots * kPointerSize);
  #endif
          __ push(eax);
          __ mov(Operand(eax), Immediate(slots));
          Label loop;
          __ bind(&loop);
          __ mov(MemOperand(esp, eax, times_4, 0),
                 Immediate(kSlotsZapValue));
          __ dec(eax);
          __ j(not_zero, &loop);
          __ pop(eax);
        } else {
          __ sub(Operand(esp), Immediate(slots * kPointerSize));
  #ifdef _MSC_VER
          MakeSureStackPagesMapped(slots * kPointerSize);
  #endif
        }
  
        if (support_aligned_spilled_doubles_) {
          Comment(";;; Store dynamic frame alignment tag for spilled doubles");
          // Store dynamic frame alignment state in the first local.
          int offset = JavaScriptFrameConstants::kDynamicAlignmentStateOffset;
          if (dynamic_frame_alignment_) {
            __ mov(Operand(ebp, offset), edx);
          } else {
            __ mov(Operand(ebp, offset), Immediate(kNoAlignmentPadding));
          }
        }
      }
  
      if (info()->saves_caller_doubles() && CpuFeatures::IsSupported(SSE2)) {
        SaveCallerDoubles();
      }
    }
  
    // Possibly allocate a local context.
    int heap_slots = info_->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
    if (heap_slots > 0) {
      Comment(";;; Allocate local context");
      // Argument to NewContext is the function, which is still in edi.
      if (heap_slots <= FastNewContextStub::kMaximumSlots) {
        FastNewContextStub stub(isolate(), heap_slots);
        __ CallStub(&stub);
      } else {
        __ push(edi);
        __ CallRuntime(Runtime::kHiddenNewFunctionContext, 1);
      }
      RecordSafepoint(Safepoint::kNoLazyDeopt);
      // Context is returned in eax.  It replaces the context passed to us.
      // It's saved in the stack and kept live in esi.
      __ mov(esi, eax);
      __ mov(Operand(ebp, StandardFrameConstants::kContextOffset), eax);
  
      // Copy parameters into context if necessary.
      int num_parameters = scope()->num_parameters();
      for (int i = 0; i < num_parameters; i++) {
        Variable* var = scope()->parameter(i);
        if (var->IsContextSlot()) {
          int parameter_offset = StandardFrameConstants::kCallerSPOffset +
              (num_parameters - 1 - i) * kPointerSize;
          // Load parameter from stack.
          __ mov(eax, Operand(ebp, parameter_offset));
          // Store it in the context.
          int context_offset = Context::SlotOffset(var->index());
          __ mov(Operand(esi, context_offset), eax);
          // Update the write barrier. This clobbers eax and ebx.
          __ RecordWriteContextSlot(esi,
                                    context_offset,
                                    eax,
                                    ebx,
                                    kDontSaveFPRegs);
        }
      }
      Comment(";;; End allocate local context");
    }
  
    // Trace the call.
    if (FLAG_trace && info()->IsOptimizing()) {
      // We have not executed any compiled code yet, so esi still holds the
      // incoming context.
      __ CallRuntime(Runtime::kTraceEnter, 0);
    }
    return !is_aborted();
  }
  
  
  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();
  
      // Move state of dynamic frame alignment into edx.
    __ Move(edx, Immediate(kNoAlignmentPadding));
  
    if (support_aligned_spilled_doubles_ && dynamic_frame_alignment_) {
      Label do_not_pad, align_loop;
      // Align ebp + 4 to a multiple of 2 * kPointerSize.
      __ test(ebp, Immediate(kPointerSize));
      __ j(zero, &do_not_pad, Label::kNear);
      __ push(Immediate(0));
      __ mov(ebx, esp);
      __ mov(edx, Immediate(kAlignmentPaddingPushed));
  
      // Move all parts of the frame over one word. The frame consists of:
      // unoptimized frame slots, alignment state, context, frame pointer, return
      // address, receiver, and the arguments.
      __ mov(ecx, Immediate(scope()->num_parameters() +
             5 + graph()->osr()->UnoptimizedFrameSlots()));
  
      __ bind(&align_loop);
      __ mov(eax, Operand(ebx, 1 * kPointerSize));
      __ mov(Operand(ebx, 0), eax);
      __ add(Operand(ebx), Immediate(kPointerSize));
      __ dec(ecx);
      __ j(not_zero, &align_loop, Label::kNear);
      __ mov(Operand(ebx, 0), Immediate(kAlignmentZapValue));
      __ sub(Operand(ebp), Immediate(kPointerSize));
      __ bind(&do_not_pad);
    }
  
    // Save the first local, which is overwritten by the alignment state.
    Operand alignment_loc = MemOperand(ebp, -3 * kPointerSize);
    __ push(alignment_loc);
  
    // Set the dynamic frame alignment state.
    __ mov(alignment_loc, edx);
  
    // Adjust the frame size, subsuming the unoptimized frame into the
    // optimized frame.
    int slots = GetStackSlotCount() - graph()->osr()->UnoptimizedFrameSlots();
    ASSERT(slots >= 1);
    __ sub(esp, Immediate((slots - 1) * kPointerSize));
  }
  
  
  void LCodeGen::GenerateBodyInstructionPre(LInstruction* instr) {
    if (instr->IsCall()) {
      EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
    }
    if (!instr->IsLazyBailout() && !instr->IsGap()) {
      safepoints_.BumpLastLazySafepointIndex();
    }
    if (!CpuFeatures::IsSupported(SSE2)) FlushX87StackIfNecessary(instr);
  }
  
  
  void LCodeGen::GenerateBodyInstructionPost(LInstruction* instr) {
    if (!CpuFeatures::IsSupported(SSE2)) {
      if (instr->IsGoto()) {
        x87_stack_.LeavingBlock(current_block_, LGoto::cast(instr));
      } else if (FLAG_debug_code && FLAG_enable_slow_asserts &&
                 !instr->IsGap() && !instr->IsReturn()) {
        if (instr->ClobbersDoubleRegisters(isolate())) {
          if (instr->HasDoubleRegisterResult()) {
            ASSERT_EQ(1, x87_stack_.depth());
          } else {
            ASSERT_EQ(0, x87_stack_.depth());
          }
        }
        __ VerifyX87StackDepth(x87_stack_.depth());
      }
    }
  }
  
  
  bool LCodeGen::GenerateJumpTable() {
    Label needs_frame;
    if (jump_table_.length() > 0) {
      Comment(";;; -------------------- Jump table --------------------");
    }
    for (int i = 0; i < jump_table_.length(); i++) {
      __ bind(&jump_table_[i].label);
      Address entry = jump_table_[i].address;
      Deoptimizer::BailoutType type = jump_table_[i].bailout_type;
      int id = Deoptimizer::GetDeoptimizationId(isolate(), entry, type);
      if (id == Deoptimizer::kNotDeoptimizationEntry) {
        Comment(";;; jump table entry %d.", i);
      } else {
        Comment(";;; jump table entry %d: deoptimization bailout %d.", i, id);
      }
      if (jump_table_[i].needs_frame) {
        ASSERT(!info()->saves_caller_doubles());
        __ push(Immediate(ExternalReference::ForDeoptEntry(entry)));
        if (needs_frame.is_bound()) {
          __ jmp(&needs_frame);
        } else {
          __ bind(&needs_frame);
          __ push(MemOperand(ebp, StandardFrameConstants::kContextOffset));
          // 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.
          ASSERT(info()->IsStub());
          __ push(Immediate(Smi::FromInt(StackFrame::STUB)));
          // Push a PC inside the function so that the deopt code can find where
          // the deopt comes from. It doesn't have to be the precise return
          // address of a "calling" LAZY deopt, it only has to be somewhere
          // inside the code body.
          Label push_approx_pc;
          __ call(&push_approx_pc);
          __ bind(&push_approx_pc);
          // Push the continuation which was stashed were the ebp should
          // be. Replace it with the saved ebp.
          __ push(MemOperand(esp, 3 * kPointerSize));
          __ mov(MemOperand(esp, 4 * kPointerSize), ebp);
          __ lea(ebp, MemOperand(esp, 4 * kPointerSize));
          __ ret(0);  // Call the continuation without clobbering registers.
        }
      } else {
        if (info()->saves_caller_doubles() && CpuFeatures::IsSupported(SSE2)) {
          RestoreCallerDoubles();
        }
        __ call(entry, RelocInfo::RUNTIME_ENTRY);
      }
    }
    return !is_aborted();
  }
  
  
  bool LCodeGen::GenerateDeferredCode() {
    ASSERT(is_generating());
    if (deferred_.length() > 0) {
      for (int i = 0; !is_aborted() && i < deferred_.length(); i++) {
        LDeferredCode* code = deferred_[i];
        X87Stack copy(code->x87_stack());
        x87_stack_ = copy;
  
        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");
          ASSERT(!frame_is_built_);
          ASSERT(info()->IsStub());
          frame_is_built_ = true;
          // Build the frame in such a way that esi isn't trashed.
          __ push(ebp);  // Caller's frame pointer.
          __ push(Operand(ebp, StandardFrameConstants::kContextOffset));
          __ push(Immediate(Smi::FromInt(StackFrame::STUB)));
          __ lea(ebp, Operand(esp, 2 * kPointerSize));
          Comment(";;; Deferred code");
        }
        code->Generate();
        if (NeedsDeferredFrame()) {
          __ bind(code->done());
          Comment(";;; Destroy frame");
          ASSERT(frame_is_built_);
          frame_is_built_ = false;
          __ mov(esp, ebp);
          __ pop(ebp);
        }
        __ jmp(code->exit());
      }
    }
  
    // Deferred code 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() {
    ASSERT(is_done());
    if (!info()->IsStub()) {
      // For lazy deoptimization we need space to patch a call after every call.
      // Ensure there is always space for such patching, even if the code ends
      // in a call.
      int target_offset = masm()->pc_offset() + Deoptimizer::patch_size();
      while (masm()->pc_offset() < target_offset) {
        masm()->nop();
      }
    }
    safepoints_.Emit(masm(), GetStackSlotCount());
    return !is_aborted();
  }
  
  
  Register LCodeGen::ToRegister(int index) const {
    return Register::FromAllocationIndex(index);
  }
  
  
  X87Register LCodeGen::ToX87Register(int index) const {
    return X87Register::FromAllocationIndex(index);
  }
  
  
  XMMRegister LCodeGen::ToDoubleRegister(int index) const {
    return XMMRegister::FromAllocationIndex(index);
  }
  
  
  void LCodeGen::X87LoadForUsage(X87Register reg) {
    ASSERT(x87_stack_.Contains(reg));
    x87_stack_.Fxch(reg);
    x87_stack_.pop();
  }
  
  
  void LCodeGen::X87LoadForUsage(X87Register reg1, X87Register reg2) {
    ASSERT(x87_stack_.Contains(reg1));
    ASSERT(x87_stack_.Contains(reg2));
    x87_stack_.Fxch(reg1, 1);
    x87_stack_.Fxch(reg2);
    x87_stack_.pop();
    x87_stack_.pop();
  }
  
  
  void LCodeGen::X87Stack::Fxch(X87Register reg, int other_slot) {
    ASSERT(is_mutable_);
    ASSERT(Contains(reg) && stack_depth_ > other_slot);
    int i  = ArrayIndex(reg);
    int st = st2idx(i);
    if (st != other_slot) {
      int other_i = st2idx(other_slot);
      X87Register other = stack_[other_i];
      stack_[other_i]   = reg;
      stack_[i]         = other;
      if (st == 0) {
        __ fxch(other_slot);
      } else if (other_slot == 0) {
        __ fxch(st);
      } else {
        __ fxch(st);
        __ fxch(other_slot);
        __ fxch(st);
      }
    }
  }
  
  
  int LCodeGen::X87Stack::st2idx(int pos) {
    return stack_depth_ - pos - 1;
  }
  
  
  int LCodeGen::X87Stack::ArrayIndex(X87Register reg) {
    for (int i = 0; i < stack_depth_; i++) {
      if (stack_[i].is(reg)) return i;
    }
    UNREACHABLE();
    return -1;
  }
  
  
  bool LCodeGen::X87Stack::Contains(X87Register reg) {
    for (int i = 0; i < stack_depth_; i++) {
      if (stack_[i].is(reg)) return true;
    }
    return false;
  }
  
  
  void LCodeGen::X87Stack::Free(X87Register reg) {
    ASSERT(is_mutable_);
    ASSERT(Contains(reg));
    int i  = ArrayIndex(reg);
    int st = st2idx(i);
    if (st > 0) {
      // keep track of how fstp(i) changes the order of elements
      int tos_i = st2idx(0);
      stack_[i] = stack_[tos_i];
    }
    pop();
    __ fstp(st);
  }
  
  
  void LCodeGen::X87Mov(X87Register dst, Operand src, X87OperandType opts) {
    if (x87_stack_.Contains(dst)) {
      x87_stack_.Fxch(dst);
      __ fstp(0);
    } else {
      x87_stack_.push(dst);
    }
    X87Fld(src, opts);
  }
  
  
  void LCodeGen::X87Fld(Operand src, X87OperandType opts) {
    ASSERT(!src.is_reg_only());
    switch (opts) {
      case kX87DoubleOperand:
        __ fld_d(src);
        break;
      case kX87FloatOperand:
        __ fld_s(src);
        break;
      case kX87IntOperand:
        __ fild_s(src);
        break;
      default:
        UNREACHABLE();
    }
  }
  
  
  void LCodeGen::X87Mov(Operand dst, X87Register src, X87OperandType opts) {
    ASSERT(!dst.is_reg_only());
    x87_stack_.Fxch(src);
    switch (opts) {
      case kX87DoubleOperand:
        __ fst_d(dst);
        break;
      case kX87IntOperand:
        __ fist_s(dst);
        break;
      default:
        UNREACHABLE();
    }
  }
  
  
  void LCodeGen::X87Stack::PrepareToWrite(X87Register reg) {
    ASSERT(is_mutable_);
    if (Contains(reg)) {
      Free(reg);
    }
    // Mark this register as the next register to write to
    stack_[stack_depth_] = reg;
  }
  
  
  void LCodeGen::X87Stack::CommitWrite(X87Register reg) {
    ASSERT(is_mutable_);
    // Assert the reg is prepared to write, but not on the virtual stack yet
    ASSERT(!Contains(reg) && stack_[stack_depth_].is(reg) &&
        stack_depth_ < X87Register::kNumAllocatableRegisters);
    stack_depth_++;
  }
  
  
  void LCodeGen::X87PrepareBinaryOp(
      X87Register left, X87Register right, X87Register result) {
    // You need to use DefineSameAsFirst for x87 instructions
    ASSERT(result.is(left));
    x87_stack_.Fxch(right, 1);
    x87_stack_.Fxch(left);
  }
  
  
  void LCodeGen::X87Stack::FlushIfNecessary(LInstruction* instr, LCodeGen* cgen) {
    if (stack_depth_ > 0 && instr->ClobbersDoubleRegisters(isolate())) {
      bool double_inputs = instr->HasDoubleRegisterInput();
  
      // Flush stack from tos down, since FreeX87() will mess with tos
      for (int i = stack_depth_-1; i >= 0; i--) {
        X87Register reg = stack_[i];
        // Skip registers which contain the inputs for the next instruction
        // when flushing the stack
        if (double_inputs && instr->IsDoubleInput(reg, cgen)) {
          continue;
        }
        Free(reg);
        if (i < stack_depth_-1) i++;
      }
    }
    if (instr->IsReturn()) {
      while (stack_depth_ > 0) {
        __ fstp(0);
        stack_depth_--;
      }
      if (FLAG_debug_code && FLAG_enable_slow_asserts) __ VerifyX87StackDepth(0);
    }
  }
  
  
  void LCodeGen::X87Stack::LeavingBlock(int current_block_id, LGoto* goto_instr) {
    ASSERT(stack_depth_ <= 1);
    // If ever used for new stubs producing two pairs of doubles joined into two
    // phis this assert hits. That situation is not handled, since the two stacks
    // might have st0 and st1 swapped.
    if (current_block_id + 1 != goto_instr->block_id()) {
      // If we have a value on the x87 stack on leaving a block, it must be a
      // phi input. If the next block we compile is not the join block, we have
      // to discard the stack state.
      stack_depth_ = 0;
    }
  }
  
  
  void LCodeGen::EmitFlushX87ForDeopt() {
    // The deoptimizer does not support X87 Registers. But as long as we
    // deopt from a stub its not a problem, since we will re-materialize the
    // original stub inputs, which can't be double registers.
    ASSERT(info()->IsStub());
    if (FLAG_debug_code && FLAG_enable_slow_asserts) {
      __ pushfd();
      __ VerifyX87StackDepth(x87_stack_.depth());
      __ popfd();
    }
    for (int i = 0; i < x87_stack_.depth(); i++) __ fstp(0);
  }
  
  
  Register LCodeGen::ToRegister(LOperand* op) const {
    ASSERT(op->IsRegister());
    return ToRegister(op->index());
  }
  
  
  X87Register LCodeGen::ToX87Register(LOperand* op) const {
    ASSERT(op->IsDoubleRegister());
    return ToX87Register(op->index());
  }
  
  
  XMMRegister LCodeGen::ToDoubleRegister(LOperand* op) const {
    ASSERT(op->IsDoubleRegister());
    return ToDoubleRegister(op->index());
  }
  
  
  int32_t LCodeGen::ToInteger32(LConstantOperand* op) const {
    return ToRepresentation(op, Representation::Integer32());
  }
  
  
  int32_t LCodeGen::ToRepresentation(LConstantOperand* op,
                                     const Representation& r) const {
    HConstant* constant = chunk_->LookupConstant(op);
    int32_t value = constant->Integer32Value();
    if (r.IsInteger32()) return value;
    ASSERT(r.IsSmiOrTagged());
    return reinterpret_cast<int32_t>(Smi::FromInt(value));
  }
  
  
  Handle<Object> LCodeGen::ToHandle(LConstantOperand* op) const {
    HConstant* constant = chunk_->LookupConstant(op);
    ASSERT(chunk_->LookupLiteralRepresentation(op).IsSmiOrTagged());
    return constant->handle(isolate());
  }
  
  
  double LCodeGen::ToDouble(LConstantOperand* op) const {
    HConstant* constant = chunk_->LookupConstant(op);
    ASSERT(constant->HasDoubleValue());
    return constant->DoubleValue();
  }
  
  
  ExternalReference LCodeGen::ToExternalReference(LConstantOperand* op) const {
    HConstant* constant = chunk_->LookupConstant(op);
    ASSERT(constant->HasExternalReferenceValue());
    return constant->ExternalReferenceValue();
  }
  
  
  bool LCodeGen::IsInteger32(LConstantOperand* op) const {
    return chunk_->LookupLiteralRepresentation(op).IsSmiOrInteger32();
  }
  
  
  bool LCodeGen::IsSmi(LConstantOperand* op) const {
    return chunk_->LookupLiteralRepresentation(op).IsSmi();
  }
  
  
  static int ArgumentsOffsetWithoutFrame(int index) {
    ASSERT(index < 0);
    return -(index + 1) * kPointerSize + kPCOnStackSize;
  }
  
  
  Operand LCodeGen::ToOperand(LOperand* op) const {
    if (op->IsRegister()) return Operand(ToRegister(op));
    if (op->IsDoubleRegister()) return Operand(ToDoubleRegister(op));
    ASSERT(op->IsStackSlot() || op->IsDoubleStackSlot());
    if (NeedsEagerFrame()) {
      return Operand(ebp, StackSlotOffset(op->index()));
    } else {
      // Retrieve parameter without eager stack-frame relative to the
      // stack-pointer.
      return Operand(esp, ArgumentsOffsetWithoutFrame(op->index()));
    }
  }
  
  
  Operand LCodeGen::HighOperand(LOperand* op) {
    ASSERT(op->IsDoubleStackSlot());
    if (NeedsEagerFrame()) {
      return Operand(ebp, StackSlotOffset(op->index()) + kPointerSize);
    } else {
      // Retrieve parameter without eager stack-frame relative to the
      // stack-pointer.
      return Operand(
          esp, ArgumentsOffsetWithoutFrame(op->index()) + kPointerSize);
    }
  }
  
  
  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();
    // The output frame height does not include the parameters.
    int height = translation_size - environment->parameter_count();
  
    WriteTranslation(environment->outer(), translation);
    bool has_closure_id = !info()->closure().is_null() &&
        !info()->closure().is_identical_to(environment->closure());
    int closure_id = has_closure_id
        ? DefineDeoptimizationLiteral(environment->closure())
        : Translation::kSelfLiteralId;
    switch (environment->frame_type()) {
      case JS_FUNCTION:
        translation->BeginJSFrame(environment->ast_id(), closure_id, height);
        break;
      case JS_CONSTRUCT:
        translation->BeginConstructStubFrame(closure_id, translation_size);
        break;
      case JS_GETTER:
        ASSERT(translation_size == 1);
        ASSERT(height == 0);
        translation->BeginGetterStubFrame(closure_id);
        break;
      case JS_SETTER:
        ASSERT(translation_size == 2);
        ASSERT(height == 0);
        translation->BeginSetterStubFrame(closure_id);
        break;
      case ARGUMENTS_ADAPTOR:
        translation->BeginArgumentsAdaptorFrame(closure_id, translation_size);
        break;
      case STUB:
        translation->BeginCompiledStubFrame();
        break;
      default:
        UNREACHABLE();
    }
  
    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()) {
      if (is_tagged) {
        translation->StoreStackSlot(op->index());
      } else if (is_uint32) {
        translation->StoreUint32StackSlot(op->index());
      } else {
        translation->StoreInt32StackSlot(op->index());
      }
    } else if (op->IsDoubleStackSlot()) {
      translation->StoreDoubleStackSlot(op->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()) {
      XMMRegister 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::CallCodeGeneric(Handle<Code> code,
                                 RelocInfo::Mode mode,
                                 LInstruction* instr,
                                 SafepointMode safepoint_mode) {
    ASSERT(instr != NULL);
    __ call(code, mode);
    RecordSafepointWithLazyDeopt(instr, safepoint_mode);
  
    // Signal that we don't inline smi code before these stubs in the
    // optimizing code generator.
    if (code->kind() == Code::BINARY_OP_IC ||
        code->kind() == Code::COMPARE_IC) {
      __ nop();
    }
  }
  
  
  void LCodeGen::CallCode(Handle<Code> code,
                          RelocInfo::Mode mode,
                          LInstruction* instr) {
    CallCodeGeneric(code, mode, instr, RECORD_SIMPLE_SAFEPOINT);
  }
  
  
  void LCodeGen::CallRuntime(const Runtime::Function* fun,
                             int argc,
                             LInstruction* instr,
                             SaveFPRegsMode save_doubles) {
    ASSERT(instr != NULL);
    ASSERT(instr->HasPointerMap());
  
    __ CallRuntime(fun, argc, save_doubles);
  
    RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
  
    ASSERT(info()->is_calling());
  }
  
  
  void LCodeGen::LoadContextFromDeferred(LOperand* context) {
    if (context->IsRegister()) {
      if (!ToRegister(context).is(esi)) {
        __ mov(esi, ToRegister(context));
      }
    } else if (context->IsStackSlot()) {
      __ mov(esi, ToOperand(context));
    } else if (context->IsConstantOperand()) {
      HConstant* constant =
          chunk_->LookupConstant(LConstantOperand::cast(context));
      __ LoadObject(esi, Handle<Object>::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);
  
    ASSERT(info()->is_calling());
  }
  
  
  void LCodeGen::RegisterEnvironmentForDeoptimization(
      LEnvironment* environment, Safepoint::DeoptMode mode) {
    environment->set_has_been_used();
    if (!environment->HasBeenRegistered()) {
      // Physical stack frame layout:
      // -x ............. -4  0 ..................................... y
      // [incoming arguments] [spill slots] [pushed outgoing arguments]
  
      // Layout of the environment:
      // 0 ..................................................... size-1
      // [parameters] [locals] [expression stack including arguments]
  
      // Layout of the translation:
      // 0 ........................................................ size - 1 + 4
      // [expression stack including arguments] [locals] [4 words] [parameters]
      // |>------------  translation_size ------------<|
  
      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::DeoptimizeIf(Condition cc,
                              LEnvironment* environment,
                              Deoptimizer::BailoutType bailout_type) {
    RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
    ASSERT(environment->HasBeenRegistered());
    int id = environment->deoptimization_index();
    ASSERT(info()->IsOptimizing() || info()->IsStub());
    Address entry =
        Deoptimizer::GetDeoptimizationEntry(isolate(), id, bailout_type);
    if (entry == NULL) {
      Abort(kBailoutWasNotPrepared);
      return;
    }
  
    if (DeoptEveryNTimes()) {
      ExternalReference count = ExternalReference::stress_deopt_count(isolate());
      Label no_deopt;
      __ pushfd();
      __ push(eax);
      __ mov(eax, Operand::StaticVariable(count));
      __ sub(eax, Immediate(1));
      __ j(not_zero, &no_deopt, Label::kNear);
      if (FLAG_trap_on_deopt) __ int3();
      __ mov(eax, Immediate(FLAG_deopt_every_n_times));
      __ mov(Operand::StaticVariable(count), eax);
      __ pop(eax);
      __ popfd();
      ASSERT(frame_is_built_);
      __ call(entry, RelocInfo::RUNTIME_ENTRY);
      __ bind(&no_deopt);
      __ mov(Operand::StaticVariable(count), eax);
      __ pop(eax);
      __ popfd();
    }
  
    // Before Instructions which can deopt, we normally flush the x87 stack. But
    // we can have inputs or outputs of the current instruction on the stack,
    // thus we need to flush them here from the physical stack to leave it in a
    // consistent state.
    if (x87_stack_.depth() > 0) {
      Label done;
      if (cc != no_condition) __ j(NegateCondition(cc), &done, Label::kNear);
      EmitFlushX87ForDeopt();
      __ bind(&done);
    }
  
    if (info()->ShouldTrapOnDeopt()) {
      Label done;
      if (cc != no_condition) __ j(NegateCondition(cc), &done, Label::kNear);
      __ int3();
      __ bind(&done);
    }
  
    ASSERT(info()->IsStub() || frame_is_built_);
    if (cc == no_condition && frame_is_built_) {
      __ call(entry, RelocInfo::RUNTIME_ENTRY);
    } else {
      // We often have several deopts to the same entry, reuse the last
      // jump entry if this is the case.
      if (jump_table_.is_empty() ||
          jump_table_.last().address != entry ||
          jump_table_.last().needs_frame != !frame_is_built_ ||
          jump_table_.last().bailout_type != bailout_type) {
        Deoptimizer::JumpTableEntry table_entry(entry,
                                                bailout_type,
                                                !frame_is_built_);
        jump_table_.Add(table_entry, zone());
      }
      if (cc == no_condition) {
        __ jmp(&jump_table_.last().label);
      } else {
        __ j(cc, &jump_table_.last().label);
      }
    }
  }
  
  
  void LCodeGen::DeoptimizeIf(Condition cc,
                              LEnvironment* environment) {
    Deoptimizer::BailoutType bailout_type = info()->IsStub()
        ? Deoptimizer::LAZY
        : Deoptimizer::EAGER;
    DeoptimizeIf(cc, environment, bailout_type);
  }
  
  
  void LCodeGen::PopulateDeoptimizationData(Handle<Code> code) {
    int length = deoptimizations_.length();
    if (length == 0) return;
    Handle<DeoptimizationInputData> data =
        DeoptimizationInputData::New(isolate(), length, TENURED);
  
    Handle<ByteArray> translations =
        translations_.CreateByteArray(isolate()->factory());
    data->SetTranslationByteArray(*translations);
    data->SetInlinedFunctionCount(Smi::FromInt(inlined_function_count_));
    data->SetOptimizationId(Smi::FromInt(info_->optimization_id()));
    if (info_->IsOptimizing()) {
      // Reference to shared function info does not change between phases.
      AllowDeferredHandleDereference allow_handle_dereference;
      data->SetSharedFunctionInfo(*info_->shared_info());
    } else {
      data->SetSharedFunctionInfo(Smi::FromInt(0));
    }
  
    Handle<FixedArray> literals =
        factory()->NewFixedArray(deoptimization_literals_.length(), TENURED);
    { AllowDeferredHandleDereference copy_handles;
      for (int i = 0; i < deoptimization_literals_.length(); i++) {
        literals->set(i, *deoptimization_literals_[i]);
      }
      data->SetLiteralArray(*literals);
    }
  
    data->SetOsrAstId(Smi::FromInt(info_->osr_ast_id().ToInt()));
    data->SetOsrPcOffset(Smi::FromInt(osr_pc_offset_));
  
    // Populate the deoptimization entries.
    for (int i = 0; i < length; i++) {
      LEnvironment* env = deoptimizations_[i];
      data->SetAstId(i, env->ast_id());
      data->SetTranslationIndex(i, Smi::FromInt(env->translation_index()));
      data->SetArgumentsStackHeight(i,
                                    Smi::FromInt(env->arguments_stack_height()));
      data->SetPc(i, Smi::FromInt(env->pc_offset()));
    }
    code->set_deoptimization_data(*data);
  }
  
  
  int LCodeGen::DefineDeoptimizationLiteral(Handle<Object> literal) {
    int result = deoptimization_literals_.length();
    for (int i = 0; i < deoptimization_literals_.length(); ++i) {
      if (deoptimization_literals_[i].is_identical_to(literal)) return i;
    }
    deoptimization_literals_.Add(literal, zone());
    return result;
  }
  
  
  void LCodeGen::PopulateDeoptimizationLiteralsWithInlinedFunctions() {
    ASSERT(deoptimization_literals_.length() == 0);
  
    const ZoneList<Handle<JSFunction> >* inlined_closures =
        chunk()->inlined_closures();
  
    for (int i = 0, length = inlined_closures->length();
         i < length;
         i++) {
      DefineDeoptimizationLiteral(inlined_closures->at(i));
    }
  
    inlined_function_count_ = deoptimization_literals_.length();
  }
  
  
  void LCodeGen::RecordSafepointWithLazyDeopt(
      LInstruction* instr, SafepointMode safepoint_mode) {
    if (safepoint_mode == RECORD_SIMPLE_SAFEPOINT) {
      RecordSafepoint(instr->pointer_map(), Safepoint::kLazyDeopt);
    } else {
      ASSERT(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) {
    ASSERT(kind == expected_safepoint_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 mode) {
    RecordSafepoint(pointers, Safepoint::kSimple, 0, mode);
  }
  
  
  void LCodeGen::RecordSafepoint(Safepoint::DeoptMode mode) {
    LPointerMap empty_pointers(zone());
    RecordSafepoint(&empty_pointers, mode);
  }
  
  
  void LCodeGen::RecordSafepointWithRegisters(LPointerMap* pointers,
                                              int arguments,
                                              Safepoint::DeoptMode mode) {
    RecordSafepoint(pointers, Safepoint::kWithRegisters, arguments, mode);
  }
  
  
  void LCodeGen::RecordAndWritePosition(int position) {
    if (position == RelocInfo::kNoPosition) return;
    masm()->positions_recorder()->RecordPosition(position);
    masm()->positions_recorder()->WriteRecordedPositions();
  }
  
  
  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));
    __ bind(label->label());
    current_block_ = label->block_id();
    DoGap(label);
  }
  
  
  void LCodeGen::DoParallelMove(LParallelMove* move) {
    resolver_.Resolve(move);
  }
  
  
  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) DoParallelMove(move);
    }
  }
  
  
  void LCodeGen::DoInstructionGap(LInstructionGap* instr) {
    DoGap(instr);
  }
  
  
  void LCodeGen::DoParameter(LParameter* instr) {
    // Nothing to do.
  }
  
  
  void LCodeGen::DoCallStub(LCallStub* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->result()).is(eax));
    switch (instr->hydrogen()->major_key()) {
      case CodeStub::RegExpExec: {
        RegExpExecStub stub(isolate());
        CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
        break;
      }
      case CodeStub::SubString: {
        SubStringStub stub(isolate());
        CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
        break;
      }
      case CodeStub::StringCompare: {
        StringCompareStub stub(isolate());
        CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
        break;
      }
      default:
        UNREACHABLE();
    }
  }
  
  
  void LCodeGen::DoUnknownOSRValue(LUnknownOSRValue* instr) {
    GenerateOsrPrologue();
  }
  
  
  void LCodeGen::DoModByPowerOf2I(LModByPowerOf2I* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    ASSERT(dividend.is(ToRegister(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)) {
      __ test(dividend, dividend);
      __ j(not_sign, &dividend_is_not_negative, Label::kNear);
      // Note that this is correct even for kMinInt operands.
      __ neg(dividend);
      __ and_(dividend, mask);
      __ neg(dividend);
      if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
        DeoptimizeIf(zero, instr->environment());
      }
      __ jmp(&done, Label::kNear);
    }
  
    __ bind(&dividend_is_not_negative);
    __ and_(dividend, mask);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoModByConstI(LModByConstI* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    ASSERT(ToRegister(instr->result()).is(eax));
  
    if (divisor == 0) {
      DeoptimizeIf(no_condition, instr->environment());
      return;
    }
  
    __ TruncatingDiv(dividend, Abs(divisor));
    __ imul(edx, edx, Abs(divisor));
    __ mov(eax, dividend);
    __ sub(eax, edx);
  
    // Check for negative zero.
    HMod* hmod = instr->hydrogen();
    if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
      Label remainder_not_zero;
      __ j(not_zero, &remainder_not_zero, Label::kNear);
      __ cmp(dividend, Immediate(0));
      DeoptimizeIf(less, instr->environment());
      __ bind(&remainder_not_zero);
    }
  }
  
  
  void LCodeGen::DoModI(LModI* instr) {
    HMod* hmod = instr->hydrogen();
  
    Register left_reg = ToRegister(instr->left());
    ASSERT(left_reg.is(eax));
    Register right_reg = ToRegister(instr->right());
    ASSERT(!right_reg.is(eax));
    ASSERT(!right_reg.is(edx));
    Register result_reg = ToRegister(instr->result());
    ASSERT(result_reg.is(edx));
  
    Label done;
    // Check for x % 0, idiv would signal a divide error. We have to
    // deopt in this case because we can't return a NaN.
    if (hmod->CheckFlag(HValue::kCanBeDivByZero)) {
      __ test(right_reg, Operand(right_reg));
      DeoptimizeIf(zero, instr->environment());
    }
  
    // Check for kMinInt % -1, idiv would signal a divide error. We
    // have to deopt if we care about -0, because we can't return that.
    if (hmod->CheckFlag(HValue::kCanOverflow)) {
      Label no_overflow_possible;
      __ cmp(left_reg, kMinInt);
      __ j(not_equal, &no_overflow_possible, Label::kNear);
      __ cmp(right_reg, -1);
      if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
        DeoptimizeIf(equal, instr->environment());
      } else {
        __ j(not_equal, &no_overflow_possible, Label::kNear);
        __ Move(result_reg, Immediate(0));
        __ jmp(&done, Label::kNear);
      }
      __ bind(&no_overflow_possible);
    }
  
    // Sign extend dividend in eax into edx:eax.
    __ cdq();
  
    // If we care about -0, test if the dividend is <0 and the result is 0.
    if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) {
      Label positive_left;
      __ test(left_reg, Operand(left_reg));
      __ j(not_sign, &positive_left, Label::kNear);
      __ idiv(right_reg);
      __ test(result_reg, Operand(result_reg));
      DeoptimizeIf(zero, instr->environment());
      __ jmp(&done, Label::kNear);
      __ bind(&positive_left);
    }
    __ idiv(right_reg);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoDivByPowerOf2I(LDivByPowerOf2I* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    Register result = ToRegister(instr->result());
    ASSERT(divisor == kMinInt || IsPowerOf2(Abs(divisor)));
    ASSERT(!result.is(dividend));
  
    // Check for (0 / -x) that will produce negative zero.
    HDiv* hdiv = instr->hydrogen();
    if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
      __ test(dividend, dividend);
      DeoptimizeIf(zero, instr->environment());
    }
    // Check for (kMinInt / -1).
    if (hdiv->CheckFlag(HValue::kCanOverflow) && divisor == -1) {
      __ cmp(dividend, kMinInt);
      DeoptimizeIf(zero, instr->environment());
    }
    // 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);
      __ test(dividend, Immediate(mask));
      DeoptimizeIf(not_zero, instr->environment());
    }
    __ Move(result, dividend);
    int32_t shift = WhichPowerOf2Abs(divisor);
    if (shift > 0) {
      // The arithmetic shift is always OK, the 'if' is an optimization only.
      if (shift > 1) __ sar(result, 31);
      __ shr(result, 32 - shift);
      __ add(result, dividend);
      __ sar(result, shift);
    }
    if (divisor < 0) __ neg(result);
  }
  
  
  void LCodeGen::DoDivByConstI(LDivByConstI* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    ASSERT(ToRegister(instr->result()).is(edx));
  
    if (divisor == 0) {
      DeoptimizeIf(no_condition, instr->environment());
      return;
    }
  
    // Check for (0 / -x) that will produce negative zero.
    HDiv* hdiv = instr->hydrogen();
    if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
      __ test(dividend, dividend);
      DeoptimizeIf(zero, instr->environment());
    }
  
    __ TruncatingDiv(dividend, Abs(divisor));
    if (divisor < 0) __ neg(edx);
  
    if (!hdiv->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
      __ mov(eax, edx);
      __ imul(eax, eax, divisor);
      __ sub(eax, dividend);
      DeoptimizeIf(not_equal, instr->environment());
    }
  }
  
  
  // TODO(svenpanne) Refactor this to avoid code duplication with DoFlooringDivI.
  void LCodeGen::DoDivI(LDivI* instr) {
    HBinaryOperation* hdiv = instr->hydrogen();
    Register dividend = ToRegister(instr->dividend());
    Register divisor = ToRegister(instr->divisor());
    Register remainder = ToRegister(instr->temp());
    ASSERT(dividend.is(eax));
    ASSERT(remainder.is(edx));
    ASSERT(ToRegister(instr->result()).is(eax));
    ASSERT(!divisor.is(eax));
    ASSERT(!divisor.is(edx));
  
    // Check for x / 0.
    if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
      __ test(divisor, divisor);
      DeoptimizeIf(zero, instr->environment());
    }
  
    // Check for (0 / -x) that will produce negative zero.
    if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
      Label dividend_not_zero;
      __ test(dividend, dividend);
      __ j(not_zero, &dividend_not_zero, Label::kNear);
      __ test(divisor, divisor);
      DeoptimizeIf(sign, instr->environment());
      __ bind(&dividend_not_zero);
    }
  
    // Check for (kMinInt / -1).
    if (hdiv->CheckFlag(HValue::kCanOverflow)) {
      Label dividend_not_min_int;
      __ cmp(dividend, kMinInt);
      __ j(not_zero, &dividend_not_min_int, Label::kNear);
      __ cmp(divisor, -1);
      DeoptimizeIf(zero, instr->environment());
      __ bind(&dividend_not_min_int);
    }
  
    // Sign extend to edx (= remainder).
    __ cdq();
    __ idiv(divisor);
  
    if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
      // Deoptimize if remainder is not 0.
      __ test(remainder, remainder);
      DeoptimizeIf(not_zero, instr->environment());
    }
  }
  
  
  void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    ASSERT(dividend.is(ToRegister(instr->result())));
  
    // If the divisor is positive, things are easy: There can be no deopts and we
    // can simply do an arithmetic right shift.
    if (divisor == 1) return;
    int32_t shift = WhichPowerOf2Abs(divisor);
    if (divisor > 1) {
      __ sar(dividend, shift);
      return;
    }
  
    // If the divisor is negative, we have to negate and handle edge cases.
    __ neg(dividend);
    if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
      DeoptimizeIf(zero, instr->environment());
    }
  
    if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
      __ sar(dividend, shift);
      return;
    }
  
    // Dividing by -1 is basically negation, unless we overflow.
    if (divisor == -1) {
      DeoptimizeIf(overflow, instr->environment());
      return;
    }
  
    Label not_kmin_int, done;
    __ j(no_overflow, &not_kmin_int, Label::kNear);
    __ mov(dividend, Immediate(kMinInt / divisor));
    __ jmp(&done, Label::kNear);
    __ bind(&not_kmin_int);
    __ sar(dividend, shift);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoFlooringDivByConstI(LFlooringDivByConstI* instr) {
    Register dividend = ToRegister(instr->dividend());
    int32_t divisor = instr->divisor();
    ASSERT(ToRegister(instr->result()).is(edx));
  
    if (divisor == 0) {
      DeoptimizeIf(no_condition, instr->environment());
      return;
    }
  
    // Check for (0 / -x) that will produce negative zero.
    HMathFloorOfDiv* hdiv = instr->hydrogen();
    if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) {
      __ test(dividend, dividend);
      DeoptimizeIf(zero, instr->environment());
    }
  
    // 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(dividend, Abs(divisor));
      if (divisor < 0) __ neg(edx);
      return;
    }
  
    // In the general case we may need to adjust before and after the truncating
    // division to get a flooring division.
    Register temp = ToRegister(instr->temp3());
    ASSERT(!temp.is(dividend) && !temp.is(eax) && !temp.is(edx));
    Label needs_adjustment, done;
    __ cmp(dividend, Immediate(0));
    __ j(divisor > 0 ? less : greater, &needs_adjustment, Label::kNear);
    __ TruncatingDiv(dividend, Abs(divisor));
    if (divisor < 0) __ neg(edx);
    __ jmp(&done, Label::kNear);
    __ bind(&needs_adjustment);
    __ lea(temp, Operand(dividend, divisor > 0 ? 1 : -1));
    __ TruncatingDiv(temp, Abs(divisor));
    if (divisor < 0) __ neg(edx);
    __ dec(edx);
    __ bind(&done);
  }
  
  
  // TODO(svenpanne) Refactor this to avoid code duplication with DoDivI.
  void LCodeGen::DoFlooringDivI(LFlooringDivI* instr) {
    HBinaryOperation* hdiv = instr->hydrogen();
    Register dividend = ToRegister(instr->dividend());
    Register divisor = ToRegister(instr->divisor());
    Register remainder = ToRegister(instr->temp());
    Register result = ToRegister(instr->result());
    ASSERT(dividend.is(eax));
    ASSERT(remainder.is(edx));
    ASSERT(result.is(eax));
    ASSERT(!divisor.is(eax));
    ASSERT(!divisor.is(edx));
  
    // Check for x / 0.
    if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
      __ test(divisor, divisor);
      DeoptimizeIf(zero, instr->environment());
    }
  
    // Check for (0 / -x) that will produce negative zero.
    if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
      Label dividend_not_zero;
      __ test(dividend, dividend);
      __ j(not_zero, &dividend_not_zero, Label::kNear);
      __ test(divisor, divisor);
      DeoptimizeIf(sign, instr->environment());
      __ bind(&dividend_not_zero);
    }
  
    // Check for (kMinInt / -1).
    if (hdiv->CheckFlag(HValue::kCanOverflow)) {
      Label dividend_not_min_int;
      __ cmp(dividend, kMinInt);
      __ j(not_zero, &dividend_not_min_int, Label::kNear);
      __ cmp(divisor, -1);
      DeoptimizeIf(zero, instr->environment());
      __ bind(&dividend_not_min_int);
    }
  
    // Sign extend to edx (= remainder).
    __ cdq();
    __ idiv(divisor);
  
    Label done;
    __ test(remainder, remainder);
    __ j(zero, &done, Label::kNear);
    __ xor_(remainder, divisor);
    __ sar(remainder, 31);
    __ add(result, remainder);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoMulI(LMulI* instr) {
    Register left = ToRegister(instr->left());
    LOperand* right = instr->right();
  
    if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
      __ mov(ToRegister(instr->temp()), left);
    }
  
    if (right->IsConstantOperand()) {
      // Try strength reductions on the multiplication.
      // All replacement instructions are at most as long as the imul
      // and have better latency.
      int constant = ToInteger32(LConstantOperand::cast(right));
      if (constant == -1) {
        __ neg(left);
      } else if (constant == 0) {
        __ xor_(left, Operand(left));
      } else if (constant == 2) {
        __ add(left, Operand(left));
      } else if (!instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
        // If we know that the multiplication can't overflow, it's safe to
        // use instructions that don't set the overflow flag for the
        // multiplication.
        switch (constant) {
          case 1:
            // Do nothing.
            break;
          case 3:
            __ lea(left, Operand(left, left, times_2, 0));
            break;
          case 4:
            __ shl(left, 2);
            break;
          case 5:
            __ lea(left, Operand(left, left, times_4, 0));
            break;
          case 8:
            __ shl(left, 3);
            break;
          case 9:
            __ lea(left, Operand(left, left, times_8, 0));
            break;
          case 16:
            __ shl(left, 4);
            break;
          default:
            __ imul(left, left, constant);
            break;
        }
      } else {
        __ imul(left, left, constant);
      }
    } else {
      if (instr->hydrogen()->representation().IsSmi()) {
        __ SmiUntag(left);
      }
      __ imul(left, ToOperand(right));
    }
  
    if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
      DeoptimizeIf(overflow, instr->environment());
    }
  
    if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
      // Bail out if the result is supposed to be negative zero.
      Label done;
      __ test(left, Operand(left));
      __ j(not_zero, &done, Label::kNear);
      if (right->IsConstantOperand()) {
        if (ToInteger32(LConstantOperand::cast(right)) < 0) {
          DeoptimizeIf(no_condition, instr->environment());
        } else if (ToInteger32(LConstantOperand::cast(right)) == 0) {
          __ cmp(ToRegister(instr->temp()), Immediate(0));
          DeoptimizeIf(less, instr->environment());
        }
      } else {
        // Test the non-zero operand for negative sign.
        __ or_(ToRegister(instr->temp()), ToOperand(right));
        DeoptimizeIf(sign, instr->environment());
      }
      __ bind(&done);
    }
  }
  
  
  void LCodeGen::DoBitI(LBitI* instr) {
    LOperand* left = instr->left();
    LOperand* right = instr->right();
    ASSERT(left->Equals(instr->result()));
    ASSERT(left->IsRegister());
  
    if (right->IsConstantOperand()) {
      int32_t right_operand =
          ToRepresentation(LConstantOperand::cast(right),
                           instr->hydrogen()->representation());
      switch (instr->op()) {
        case Token::BIT_AND:
          __ and_(ToRegister(left), right_operand);
          break;
        case Token::BIT_OR:
          __ or_(ToRegister(left), right_operand);
          break;
        case Token::BIT_XOR:
          if (right_operand == int32_t(~0)) {
            __ not_(ToRegister(left));
          } else {
            __ xor_(ToRegister(left), right_operand);
          }
          break;
        default:
          UNREACHABLE();
          break;
      }
    } else {
      switch (instr->op()) {
        case Token::BIT_AND:
          __ and_(ToRegister(left), ToOperand(right));
          break;
        case Token::BIT_OR:
          __ or_(ToRegister(left), ToOperand(right));
          break;
        case Token::BIT_XOR:
          __ xor_(ToRegister(left), ToOperand(right));
          break;
        default:
          UNREACHABLE();
          break;
      }
    }
  }
  
  
  void LCodeGen::DoShiftI(LShiftI* instr) {
    LOperand* left = instr->left();
    LOperand* right = instr->right();
    ASSERT(left->Equals(instr->result()));
    ASSERT(left->IsRegister());
    if (right->IsRegister()) {
      ASSERT(ToRegister(right).is(ecx));
  
      switch (instr->op()) {
        case Token::ROR:
          __ ror_cl(ToRegister(left));
          if (instr->can_deopt()) {
            __ test(ToRegister(left), ToRegister(left));
            DeoptimizeIf(sign, instr->environment());
          }
          break;
        case Token::SAR:
          __ sar_cl(ToRegister(left));
          break;
        case Token::SHR:
          __ shr_cl(ToRegister(left));
          if (instr->can_deopt()) {
            __ test(ToRegister(left), ToRegister(left));
            DeoptimizeIf(sign, instr->environment());
          }
          break;
        case Token::SHL:
          __ shl_cl(ToRegister(left));
          break;
        default:
          UNREACHABLE();
          break;
      }
    } else {
      int value = ToInteger32(LConstantOperand::cast(right));
      uint8_t shift_count = static_cast<uint8_t>(value & 0x1F);
      switch (instr->op()) {
        case Token::ROR:
          if (shift_count == 0 && instr->can_deopt()) {
            __ test(ToRegister(left), ToRegister(left));
            DeoptimizeIf(sign, instr->environment());
          } else {
            __ ror(ToRegister(left), shift_count);
          }
          break;
        case Token::SAR:
          if (shift_count != 0) {
            __ sar(ToRegister(left), shift_count);
          }
          break;
        case Token::SHR:
          if (shift_count == 0 && instr->can_deopt()) {
            __ test(ToRegister(left), ToRegister(left));
            DeoptimizeIf(sign, instr->environment());
          } else {
            __ shr(ToRegister(left), shift_count);
          }
          break;
        case Token::SHL:
          if (shift_count != 0) {
            if (instr->hydrogen_value()->representation().IsSmi() &&
                instr->can_deopt()) {
              if (shift_count != 1) {
                __ shl(ToRegister(left), shift_count - 1);
              }
              __ SmiTag(ToRegister(left));
              DeoptimizeIf(overflow, instr->environment());
            } else {
              __ shl(ToRegister(left), shift_count);
            }
          }
          break;
        default:
          UNREACHABLE();
          break;
      }
    }
  }
  
  
  void LCodeGen::DoSubI(LSubI* instr) {
    LOperand* left = instr->left();
    LOperand* right = instr->right();
    ASSERT(left->Equals(instr->result()));
  
    if (right->IsConstantOperand()) {
      __ sub(ToOperand(left),
             ToImmediate(right, instr->hydrogen()->representation()));
    } else {
      __ sub(ToRegister(left), ToOperand(right));
    }
    if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
      DeoptimizeIf(overflow, instr->environment());
    }
  }
  
  
  void LCodeGen::DoConstantI(LConstantI* instr) {
    __ Move(ToRegister(instr->result()), Immediate(instr->value()));
  }
  
  
  void LCodeGen::DoConstantS(LConstantS* instr) {
    __ Move(ToRegister(instr->result()), Immediate(instr->value()));
  }
  
  
  void LCodeGen::DoConstantD(LConstantD* instr) {
    double v = instr->value();
    uint64_t int_val = BitCast<uint64_t, double>(v);
    int32_t lower = static_cast<int32_t>(int_val);
    int32_t upper = static_cast<int32_t>(int_val >> (kBitsPerInt));
    ASSERT(instr->result()->IsDoubleRegister());
  
    if (!CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
      __ push(Immediate(upper));
      __ push(Immediate(lower));
      X87Register reg = ToX87Register(instr->result());
      X87Mov(reg, Operand(esp, 0));
      __ add(Operand(esp), Immediate(kDoubleSize));
    } else {
      CpuFeatureScope scope1(masm(), SSE2);
      XMMRegister res = ToDoubleRegister(instr->result());
      if (int_val == 0) {
        __ xorps(res, res);
      } else {
        Register temp = ToRegister(instr->temp());
        if (CpuFeatures::IsSupported(SSE4_1)) {
          CpuFeatureScope scope2(masm(), SSE4_1);
          if (lower != 0) {
            __ Move(temp, Immediate(lower));
            __ movd(res, Operand(temp));
            __ Move(temp, Immediate(upper));
            __ pinsrd(res, Operand(temp), 1);
          } else {
            __ xorps(res, res);
            __ Move(temp, Immediate(upper));
            __ pinsrd(res, Operand(temp), 1);
          }
        } else {
          __ Move(temp, Immediate(upper));
          __ movd(res, Operand(temp));
          __ psllq(res, 32);
          if (lower != 0) {
            XMMRegister xmm_scratch = double_scratch0();
            __ Move(temp, Immediate(lower));
            __ movd(xmm_scratch, Operand(temp));
            __ orps(res, xmm_scratch);
          }
        }
      }
    }
  }
  
  
  void LCodeGen::DoConstantE(LConstantE* instr) {
    __ lea(ToRegister(instr->result()), Operand::StaticVariable(instr->value()));
  }
  
  
  void LCodeGen::DoConstantT(LConstantT* instr) {
    Register reg = ToRegister(instr->result());
    Handle<Object> object = instr->value(isolate());
    AllowDeferredHandleDereference smi_check;
    if (instr->hydrogen()->HasObjectMap()) {
      Handle<Map> object_map = instr->hydrogen()->ObjectMap().handle();
      ASSERT(object->IsHeapObject());
      ASSERT(!object_map->is_stable() ||
             *object_map == Handle<HeapObject>::cast(object)->map());
      USE(object_map);
    }
    __ LoadObject(reg, object);
  }
  
  
  void LCodeGen::DoMapEnumLength(LMapEnumLength* instr) {
    Register result = ToRegister(instr->result());
    Register map = ToRegister(instr->value());
    __ EnumLength(result, map);
  }
  
  
  void LCodeGen::DoDateField(LDateField* instr) {
    Register object = ToRegister(instr->date());
    Register result = ToRegister(instr->result());
    Register scratch = ToRegister(instr->temp());
    Smi* index = instr->index();
    Label runtime, done;
    ASSERT(object.is(result));
    ASSERT(object.is(eax));
  
    __ test(object, Immediate(kSmiTagMask));
    DeoptimizeIf(zero, instr->environment());
    __ CmpObjectType(object, JS_DATE_TYPE, scratch);
    DeoptimizeIf(not_equal, instr->environment());
  
    if (index->value() == 0) {
      __ mov(result, FieldOperand(object, JSDate::kValueOffset));
    } else {
      if (index->value() < JSDate::kFirstUncachedField) {
        ExternalReference stamp = ExternalReference::date_cache_stamp(isolate());
        __ mov(scratch, Operand::StaticVariable(stamp));
        __ cmp(scratch, FieldOperand(object, JSDate::kCacheStampOffset));
        __ j(not_equal, &runtime, Label::kNear);
        __ mov(result, FieldOperand(object, JSDate::kValueOffset +
                                            kPointerSize * index->value()));
        __ jmp(&done, Label::kNear);
      }
      __ bind(&runtime);
      __ PrepareCallCFunction(2, scratch);
      __ mov(Operand(esp, 0), object);
      __ mov(Operand(esp, 1 * kPointerSize), Immediate(index));
      __ CallCFunction(ExternalReference::get_date_field_function(isolate()), 2);
      __ bind(&done);
    }
  }
  
  
  Operand LCodeGen::BuildSeqStringOperand(Register string,
                                          LOperand* index,
                                          String::Encoding encoding) {
    if (index->IsConstantOperand()) {
      int offset = ToRepresentation(LConstantOperand::cast(index),
                                    Representation::Integer32());
      if (encoding == String::TWO_BYTE_ENCODING) {
        offset *= kUC16Size;
      }
      STATIC_ASSERT(kCharSize == 1);
      return FieldOperand(string, SeqString::kHeaderSize + offset);
    }
    return FieldOperand(
        string, ToRegister(index),
        encoding == String::ONE_BYTE_ENCODING ? times_1 : times_2,
        SeqString::kHeaderSize);
  }
  
  
  void LCodeGen::DoSeqStringGetChar(LSeqStringGetChar* instr) {
    String::Encoding encoding = instr->hydrogen()->encoding();
    Register result = ToRegister(instr->result());
    Register string = ToRegister(instr->string());
  
    if (FLAG_debug_code) {
      __ push(string);
      __ mov(string, FieldOperand(string, HeapObject::kMapOffset));
      __ movzx_b(string, FieldOperand(string, Map::kInstanceTypeOffset));
  
      __ and_(string, Immediate(kStringRepresentationMask | kStringEncodingMask));
      static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
      static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
      __ cmp(string, Immediate(encoding == String::ONE_BYTE_ENCODING
                               ? one_byte_seq_type : two_byte_seq_type));
      __ Check(equal, kUnexpectedStringType);
      __ pop(string);
    }
  
    Operand operand = BuildSeqStringOperand(string, instr->index(), encoding);
    if (encoding == String::ONE_BYTE_ENCODING) {
      __ movzx_b(result, operand);
    } else {
      __ movzx_w(result, operand);
    }
  }
  
  
  void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
    String::Encoding encoding = instr->hydrogen()->encoding();
    Register string = ToRegister(instr->string());
  
    if (FLAG_debug_code) {
      Register value = ToRegister(instr->value());
      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, value, encoding_mask);
    }
  
    Operand operand = BuildSeqStringOperand(string, instr->index(), encoding);
    if (instr->value()->IsConstantOperand()) {
      int value = ToRepresentation(LConstantOperand::cast(instr->value()),
                                   Representation::Integer32());
      ASSERT_LE(0, value);
      if (encoding == String::ONE_BYTE_ENCODING) {
        ASSERT_LE(value, String::kMaxOneByteCharCode);
        __ mov_b(operand, static_cast<int8_t>(value));
      } else {
        ASSERT_LE(value, String::kMaxUtf16CodeUnit);
        __ mov_w(operand, static_cast<int16_t>(value));
      }
    } else {
      Register value = ToRegister(instr->value());
      if (encoding == String::ONE_BYTE_ENCODING) {
        __ mov_b(operand, value);
      } else {
        __ mov_w(operand, value);
      }
    }
  }
  
  
  void LCodeGen::DoAddI(LAddI* instr) {
    LOperand* left = instr->left();
    LOperand* right = instr->right();
  
    if (LAddI::UseLea(instr->hydrogen()) && !left->Equals(instr->result())) {
      if (right->IsConstantOperand()) {
        int32_t offset = ToRepresentation(LConstantOperand::cast(right),
                                          instr->hydrogen()->representation());
        __ lea(ToRegister(instr->result()), MemOperand(ToRegister(left), offset));
      } else {
        Operand address(ToRegister(left), ToRegister(right), times_1, 0);
        __ lea(ToRegister(instr->result()), address);
      }
    } else {
      if (right->IsConstantOperand()) {
        __ add(ToOperand(left),
               ToImmediate(right, instr->hydrogen()->representation()));
      } else {
        __ add(ToRegister(left), ToOperand(right));
      }
      if (instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
        DeoptimizeIf(overflow, instr->environment());
      }
    }
  }
  
  
  void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    LOperand* left = instr->left();
    LOperand* right = instr->right();
    ASSERT(left->Equals(instr->result()));
    HMathMinMax::Operation operation = instr->hydrogen()->operation();
    if (instr->hydrogen()->representation().IsSmiOrInteger32()) {
      Label return_left;
      Condition condition = (operation == HMathMinMax::kMathMin)
          ? less_equal
          : greater_equal;
      if (right->IsConstantOperand()) {
        Operand left_op = ToOperand(left);
        Immediate immediate = ToImmediate(LConstantOperand::cast(instr->right()),
                                          instr->hydrogen()->representation());
        __ cmp(left_op, immediate);
        __ j(condition, &return_left, Label::kNear);
        __ mov(left_op, immediate);
      } else {
        Register left_reg = ToRegister(left);
        Operand right_op = ToOperand(right);
        __ cmp(left_reg, right_op);
        __ j(condition, &return_left, Label::kNear);
        __ mov(left_reg, right_op);
      }
      __ bind(&return_left);
    } else {
      ASSERT(instr->hydrogen()->representation().IsDouble());
      Label check_nan_left, check_zero, return_left, return_right;
      Condition condition = (operation == HMathMinMax::kMathMin) ? below : above;
      XMMRegister left_reg = ToDoubleRegister(left);
      XMMRegister right_reg = ToDoubleRegister(right);
      __ ucomisd(left_reg, right_reg);
      __ j(parity_even, &check_nan_left, Label::kNear);  // At least one NaN.
      __ j(equal, &check_zero, Label::kNear);  // left == right.
      __ j(condition, &return_left, Label::kNear);
      __ jmp(&return_right, Label::kNear);
  
      __ bind(&check_zero);
      XMMRegister xmm_scratch = double_scratch0();
      __ xorps(xmm_scratch, xmm_scratch);
      __ ucomisd(left_reg, xmm_scratch);
      __ j(not_equal, &return_left, Label::kNear);  // left == right != 0.
      // At this point, both left and right are either 0 or -0.
      if (operation == HMathMinMax::kMathMin) {
        __ orpd(left_reg, right_reg);
      } else {
        // Since we operate on +0 and/or -0, addsd and andsd have the same effect.
        __ addsd(left_reg, right_reg);
      }
      __ jmp(&return_left, Label::kNear);
  
      __ bind(&check_nan_left);
      __ ucomisd(left_reg, left_reg);  // NaN check.
      __ j(parity_even, &return_left, Label::kNear);  // left == NaN.
      __ bind(&return_right);
      __ movaps(left_reg, right_reg);
  
      __ bind(&return_left);
    }
  }
  
  
  void LCodeGen::DoArithmeticD(LArithmeticD* instr) {
    if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister left = ToDoubleRegister(instr->left());
      XMMRegister right = ToDoubleRegister(instr->right());
      XMMRegister result = ToDoubleRegister(instr->result());
      switch (instr->op()) {
        case Token::ADD:
          __ addsd(left, right);
          break;
        case Token::SUB:
          __ subsd(left, right);
          break;
        case Token::MUL:
          __ mulsd(left, right);
          break;
        case Token::DIV:
          __ divsd(left, right);
          // Don't delete this mov. It may improve performance on some CPUs,
          // when there is a mulsd depending on the result
          __ movaps(left, left);
          break;
        case Token::MOD: {
          // Pass two doubles as arguments on the stack.
          __ PrepareCallCFunction(4, eax);
          __ movsd(Operand(esp, 0 * kDoubleSize), left);
          __ movsd(Operand(esp, 1 * kDoubleSize), right);
          __ CallCFunction(
              ExternalReference::mod_two_doubles_operation(isolate()),
              4);
  
          // Return value is in st(0) on ia32.
          // Store it into the result register.
          __ sub(Operand(esp), Immediate(kDoubleSize));
          __ fstp_d(Operand(esp, 0));
          __ movsd(result, Operand(esp, 0));
          __ add(Operand(esp), Immediate(kDoubleSize));
          break;
        }
        default:
          UNREACHABLE();
          break;
      }
    } else {
      X87Register left = ToX87Register(instr->left());
      X87Register right = ToX87Register(instr->right());
      X87Register result = ToX87Register(instr->result());
      if (instr->op() != Token::MOD) {
        X87PrepareBinaryOp(left, right, result);
      }
      switch (instr->op()) {
        case Token::ADD:
          __ fadd_i(1);
          break;
        case Token::SUB:
          __ fsub_i(1);
          break;
        case Token::MUL:
          __ fmul_i(1);
          break;
        case Token::DIV:
          __ fdiv_i(1);
          break;
        case Token::MOD: {
          // Pass two doubles as arguments on the stack.
          __ PrepareCallCFunction(4, eax);
          X87Mov(Operand(esp, 1 * kDoubleSize), right);
          X87Mov(Operand(esp, 0), left);
          X87Free(right);
          ASSERT(left.is(result));
          X87PrepareToWrite(result);
          __ CallCFunction(
              ExternalReference::mod_two_doubles_operation(isolate()),
              4);
  
          // Return value is in st(0) on ia32.
          X87CommitWrite(result);
          break;
        }
        default:
          UNREACHABLE();
          break;
      }
    }
  }
  
  
  void LCodeGen::DoArithmeticT(LArithmeticT* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->left()).is(edx));
    ASSERT(ToRegister(instr->right()).is(eax));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    BinaryOpICStub stub(isolate(), instr->op(), NO_OVERWRITE);
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  }
  
  
  template<class InstrType>
  void LCodeGen::EmitBranch(InstrType instr, Condition cc) {
    int left_block = instr->TrueDestination(chunk_);
    int right_block = instr->FalseDestination(chunk_);
  
    int next_block = GetNextEmittedBlock();
  
    if (right_block == left_block || cc == no_condition) {
      EmitGoto(left_block);
    } else if (left_block == next_block) {
      __ j(NegateCondition(cc), chunk_->GetAssemblyLabel(right_block));
    } else if (right_block == next_block) {
      __ j(cc, chunk_->GetAssemblyLabel(left_block));
    } else {
      __ j(cc, chunk_->GetAssemblyLabel(left_block));
      __ jmp(chunk_->GetAssemblyLabel(right_block));
    }
  }
  
  
  template<class InstrType>
  void LCodeGen::EmitFalseBranch(InstrType instr, Condition cc) {
    int false_block = instr->FalseDestination(chunk_);
    if (cc == no_condition) {
      __ jmp(chunk_->GetAssemblyLabel(false_block));
    } else {
      __ j(cc, chunk_->GetAssemblyLabel(false_block));
    }
  }
  
  
  void LCodeGen::DoBranch(LBranch* instr) {
    Representation r = instr->hydrogen()->value()->representation();
    if (r.IsSmiOrInteger32()) {
      Register reg = ToRegister(instr->value());
      __ test(reg, Operand(reg));
      EmitBranch(instr, not_zero);
    } else if (r.IsDouble()) {
      ASSERT(!info()->IsStub());
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister reg = ToDoubleRegister(instr->value());
      XMMRegister xmm_scratch = double_scratch0();
      __ xorps(xmm_scratch, xmm_scratch);
      __ ucomisd(reg, xmm_scratch);
      EmitBranch(instr, not_equal);
    } else {
      ASSERT(r.IsTagged());
      Register reg = ToRegister(instr->value());
      HType type = instr->hydrogen()->value()->type();
      if (type.IsBoolean()) {
        ASSERT(!info()->IsStub());
        __ cmp(reg, factory()->true_value());
        EmitBranch(instr, equal);
      } else if (type.IsSmi()) {
        ASSERT(!info()->IsStub());
        __ test(reg, Operand(reg));
        EmitBranch(instr, not_equal);
      } else if (type.IsJSArray()) {
        ASSERT(!info()->IsStub());
        EmitBranch(instr, no_condition);
      } else if (type.IsHeapNumber()) {
        ASSERT(!info()->IsStub());
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister xmm_scratch = double_scratch0();
        __ xorps(xmm_scratch, xmm_scratch);
        __ ucomisd(xmm_scratch, FieldOperand(reg, HeapNumber::kValueOffset));
        EmitBranch(instr, not_equal);
      } else if (type.IsString()) {
        ASSERT(!info()->IsStub());
        __ cmp(FieldOperand(reg, String::kLengthOffset), Immediate(0));
        EmitBranch(instr, not_equal);
      } else {
        ToBooleanStub::Types expected = instr->hydrogen()->expected_input_types();
        if (expected.IsEmpty()) expected = ToBooleanStub::Types::Generic();
  
        if (expected.Contains(ToBooleanStub::UNDEFINED)) {
          // undefined -> false.
          __ cmp(reg, factory()->undefined_value());
          __ j(equal, instr->FalseLabel(chunk_));
        }
        if (expected.Contains(ToBooleanStub::BOOLEAN)) {
          // true -> true.
          __ cmp(reg, factory()->true_value());
          __ j(equal, instr->TrueLabel(chunk_));
          // false -> false.
          __ cmp(reg, factory()->false_value());
          __ j(equal, instr->FalseLabel(chunk_));
        }
        if (expected.Contains(ToBooleanStub::NULL_TYPE)) {
          // 'null' -> false.
          __ cmp(reg, factory()->null_value());
          __ j(equal, instr->FalseLabel(chunk_));
        }
  
        if (expected.Contains(ToBooleanStub::SMI)) {
          // Smis: 0 -> false, all other -> true.
          __ test(reg, Operand(reg));
          __ j(equal, instr->FalseLabel(chunk_));
          __ JumpIfSmi(reg, instr->TrueLabel(chunk_));
        } else if (expected.NeedsMap()) {
          // If we need a map later and have a Smi -> deopt.
          __ test(reg, Immediate(kSmiTagMask));
          DeoptimizeIf(zero, instr->environment());
        }
  
        Register map = no_reg;  // Keep the compiler happy.
        if (expected.NeedsMap()) {
          map = ToRegister(instr->temp());
          ASSERT(!map.is(reg));
          __ mov(map, FieldOperand(reg, HeapObject::kMapOffset));
  
          if (expected.CanBeUndetectable()) {
            // Undetectable -> false.
            __ test_b(FieldOperand(map, Map::kBitFieldOffset),
                      1 << Map::kIsUndetectable);
            __ j(not_zero, instr->FalseLabel(chunk_));
          }
        }
  
        if (expected.Contains(ToBooleanStub::SPEC_OBJECT)) {
          // spec object -> true.
          __ CmpInstanceType(map, FIRST_SPEC_OBJECT_TYPE);
          __ j(above_equal, instr->TrueLabel(chunk_));
        }
  
        if (expected.Contains(ToBooleanStub::STRING)) {
          // String value -> false iff empty.
          Label not_string;
          __ CmpInstanceType(map, FIRST_NONSTRING_TYPE);
          __ j(above_equal, &not_string, Label::kNear);
          __ cmp(FieldOperand(reg, String::kLengthOffset), Immediate(0));
          __ j(not_zero, instr->TrueLabel(chunk_));
          __ jmp(instr->FalseLabel(chunk_));
          __ bind(&not_string);
        }
  
        if (expected.Contains(ToBooleanStub::SYMBOL)) {
          // Symbol value -> true.
          __ CmpInstanceType(map, SYMBOL_TYPE);
          __ j(equal, instr->TrueLabel(chunk_));
        }
  
        if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
          // heap number -> false iff +0, -0, or NaN.
          Label not_heap_number;
          __ cmp(FieldOperand(reg, HeapObject::kMapOffset),
                 factory()->heap_number_map());
          __ j(not_equal, &not_heap_number, Label::kNear);
          if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
            CpuFeatureScope scope(masm(), SSE2);
            XMMRegister xmm_scratch = double_scratch0();
            __ xorps(xmm_scratch, xmm_scratch);
            __ ucomisd(xmm_scratch, FieldOperand(reg, HeapNumber::kValueOffset));
          } else {
            __ fldz();
            __ fld_d(FieldOperand(reg, HeapNumber::kValueOffset));
            __ FCmp();
          }
          __ j(zero, instr->FalseLabel(chunk_));
          __ jmp(instr->TrueLabel(chunk_));
          __ 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.
          DeoptimizeIf(no_condition, instr->environment());
        }
      }
    }
  }
  
  
  void LCodeGen::EmitGoto(int block) {
    if (!IsNextEmittedBlock(block)) {
      __ jmp(chunk_->GetAssemblyLabel(LookupDestination(block)));
    }
  }
  
  
  void LCodeGen::DoClobberDoubles(LClobberDoubles* instr) {
  }
  
  
  void LCodeGen::DoGoto(LGoto* instr) {
    EmitGoto(instr->block_id());
  }
  
  
  Condition LCodeGen::TokenToCondition(Token::Value op, bool is_unsigned) {
    Condition cond = no_condition;
    switch (op) {
      case Token::EQ:
      case Token::EQ_STRICT:
        cond = equal;
        break;
      case Token::NE:
      case Token::NE_STRICT:
        cond = not_equal;
        break;
      case Token::LT:
        cond = is_unsigned ? below : less;
        break;
      case Token::GT:
        cond = is_unsigned ? above : greater;
        break;
      case Token::LTE:
        cond = is_unsigned ? below_equal : less_equal;
        break;
      case Token::GTE:
        cond = is_unsigned ? above_equal : greater_equal;
        break;
      case Token::IN:
      case Token::INSTANCEOF:
      default:
        UNREACHABLE();
    }
    return cond;
  }
  
  
  void LCodeGen::DoCompareNumericAndBranch(LCompareNumericAndBranch* instr) {
    LOperand* left = instr->left();
    LOperand* right = instr->right();
    Condition cc = TokenToCondition(instr->op(), instr->is_double());
  
    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 = EvalComparison(instr->op(), left_val, right_val) ?
          instr->TrueDestination(chunk_) : instr->FalseDestination(chunk_);
      EmitGoto(next_block);
    } else {
      if (instr->is_double()) {
        if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
          CpuFeatureScope scope(masm(), SSE2);
          __ ucomisd(ToDoubleRegister(left), ToDoubleRegister(right));
        } else {
          X87LoadForUsage(ToX87Register(right), ToX87Register(left));
          __ FCmp();
        }
        // Don't base result on EFLAGS when a NaN is involved. Instead
        // jump to the false block.
        __ j(parity_even, instr->FalseLabel(chunk_));
      } else {
        if (right->IsConstantOperand()) {
          __ cmp(ToOperand(left),
                 ToImmediate(right, instr->hydrogen()->representation()));
        } else if (left->IsConstantOperand()) {
          __ cmp(ToOperand(right),
                 ToImmediate(left, instr->hydrogen()->representation()));
          // We transposed the operands. Reverse the condition.
          cc = ReverseCondition(cc);
        } else {
          __ cmp(ToRegister(left), ToOperand(right));
        }
      }
      EmitBranch(instr, cc);
    }
  }
  
  
  void LCodeGen::DoCmpObjectEqAndBranch(LCmpObjectEqAndBranch* instr) {
    Register left = ToRegister(instr->left());
  
    if (instr->right()->IsConstantOperand()) {
      Handle<Object> right = ToHandle(LConstantOperand::cast(instr->right()));
      __ CmpObject(left, right);
    } else {
      Operand right = ToOperand(instr->right());
      __ cmp(left, right);
    }
    EmitBranch(instr, equal);
  }
  
  
  void LCodeGen::DoCmpHoleAndBranch(LCmpHoleAndBranch* instr) {
    if (instr->hydrogen()->representation().IsTagged()) {
      Register input_reg = ToRegister(instr->object());
      __ cmp(input_reg, factory()->the_hole_value());
      EmitBranch(instr, equal);
      return;
    }
  
    bool use_sse2 = CpuFeatures::IsSupported(SSE2);
    if (use_sse2) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister input_reg = ToDoubleRegister(instr->object());
      __ ucomisd(input_reg, input_reg);
      EmitFalseBranch(instr, parity_odd);
    } else {
      // Put the value to the top of stack
      X87Register src = ToX87Register(instr->object());
      X87LoadForUsage(src);
      __ fld(0);
      __ fld(0);
      __ FCmp();
      Label ok;
      __ j(parity_even, &ok, Label::kNear);
      __ fstp(0);
      EmitFalseBranch(instr, no_condition);
      __ bind(&ok);
    }
  
  
    __ sub(esp, Immediate(kDoubleSize));
    if (use_sse2) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister input_reg = ToDoubleRegister(instr->object());
      __ movsd(MemOperand(esp, 0), input_reg);
    } else {
      __ fstp_d(MemOperand(esp, 0));
    }
  
    __ add(esp, Immediate(kDoubleSize));
    int offset = sizeof(kHoleNanUpper32);
    __ cmp(MemOperand(esp, -offset), Immediate(kHoleNanUpper32));
    EmitBranch(instr, equal);
  }
  
  
  void LCodeGen::DoCompareMinusZeroAndBranch(LCompareMinusZeroAndBranch* instr) {
    Representation rep = instr->hydrogen()->value()->representation();
    ASSERT(!rep.IsInteger32());
    Register scratch = ToRegister(instr->temp());
  
    if (rep.IsDouble()) {
      CpuFeatureScope use_sse2(masm(), SSE2);
      XMMRegister value = ToDoubleRegister(instr->value());
      XMMRegister xmm_scratch = double_scratch0();
      __ xorps(xmm_scratch, xmm_scratch);
      __ ucomisd(xmm_scratch, value);
      EmitFalseBranch(instr, not_equal);
      __ movmskpd(scratch, value);
      __ test(scratch, Immediate(1));
      EmitBranch(instr, not_zero);
    } else {
      Register value = ToRegister(instr->value());
      Handle<Map> map = masm()->isolate()->factory()->heap_number_map();
      __ CheckMap(value, map, instr->FalseLabel(chunk()), DO_SMI_CHECK);
      __ cmp(FieldOperand(value, HeapNumber::kExponentOffset),
             Immediate(0x1));
      EmitFalseBranch(instr, no_overflow);
      __ cmp(FieldOperand(value, HeapNumber::kMantissaOffset),
             Immediate(0x00000000));
      EmitBranch(instr, equal);
    }
  }
  
  
  Condition LCodeGen::EmitIsObject(Register input,
                                   Register temp1,
                                   Label* is_not_object,
                                   Label* is_object) {
    __ JumpIfSmi(input, is_not_object);
  
    __ cmp(input, isolate()->factory()->null_value());
    __ j(equal, is_object);
  
    __ mov(temp1, FieldOperand(input, HeapObject::kMapOffset));
    // Undetectable objects behave like undefined.
    __ test_b(FieldOperand(temp1, Map::kBitFieldOffset),
              1 << Map::kIsUndetectable);
    __ j(not_zero, is_not_object);
  
    __ movzx_b(temp1, FieldOperand(temp1, Map::kInstanceTypeOffset));
    __ cmp(temp1, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
    __ j(below, is_not_object);
    __ cmp(temp1, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
    return below_equal;
  }
  
  
  void LCodeGen::DoIsObjectAndBranch(LIsObjectAndBranch* instr) {
    Register reg = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    Condition true_cond = EmitIsObject(
        reg, temp, instr->FalseLabel(chunk_), instr->TrueLabel(chunk_));
  
    EmitBranch(instr, true_cond);
  }
  
  
  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);
    }
  
    Condition cond = masm_->IsObjectStringType(input, temp1, temp1);
  
    return cond;
  }
  
  
  void LCodeGen::DoIsStringAndBranch(LIsStringAndBranch* instr) {
    Register reg = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    SmiCheck check_needed =
        instr->hydrogen()->value()->IsHeapObject()
            ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
  
    Condition true_cond = EmitIsString(
        reg, temp, instr->FalseLabel(chunk_), check_needed);
  
    EmitBranch(instr, true_cond);
  }
  
  
  void LCodeGen::DoIsSmiAndBranch(LIsSmiAndBranch* instr) {
    Operand input = ToOperand(instr->value());
  
    __ test(input, Immediate(kSmiTagMask));
    EmitBranch(instr, zero);
  }
  
  
  void LCodeGen::DoIsUndetectableAndBranch(LIsUndetectableAndBranch* instr) {
    Register input = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    if (!instr->hydrogen()->value()->IsHeapObject()) {
      STATIC_ASSERT(kSmiTag == 0);
      __ JumpIfSmi(input, instr->FalseLabel(chunk_));
    }
    __ mov(temp, FieldOperand(input, HeapObject::kMapOffset));
    __ test_b(FieldOperand(temp, Map::kBitFieldOffset),
              1 << Map::kIsUndetectable);
    EmitBranch(instr, not_zero);
  }
  
  
  static Condition ComputeCompareCondition(Token::Value op) {
    switch (op) {
      case Token::EQ_STRICT:
      case Token::EQ:
        return equal;
      case Token::LT:
        return less;
      case Token::GT:
        return greater;
      case Token::LTE:
        return less_equal;
      case Token::GTE:
        return greater_equal;
      default:
        UNREACHABLE();
        return no_condition;
    }
  }
  
  
  void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
    Token::Value op = instr->op();
  
    Handle<Code> ic = CompareIC::GetUninitialized(isolate(), op);
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  
    Condition condition = ComputeCompareCondition(op);
    __ test(eax, Operand(eax));
  
    EmitBranch(instr, condition);
  }
  
  
  static InstanceType TestType(HHasInstanceTypeAndBranch* instr) {
    InstanceType from = instr->from();
    InstanceType to = instr->to();
    if (from == FIRST_TYPE) return to;
    ASSERT(from == to || to == LAST_TYPE);
    return from;
  }
  
  
  static Condition BranchCondition(HHasInstanceTypeAndBranch* instr) {
    InstanceType from = instr->from();
    InstanceType to = instr->to();
    if (from == to) return equal;
    if (to == LAST_TYPE) return above_equal;
    if (from == FIRST_TYPE) return below_equal;
    UNREACHABLE();
    return equal;
  }
  
  
  void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
    Register input = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    if (!instr->hydrogen()->value()->IsHeapObject()) {
      __ JumpIfSmi(input, instr->FalseLabel(chunk_));
    }
  
    __ CmpObjectType(input, TestType(instr->hydrogen()), temp);
    EmitBranch(instr, BranchCondition(instr->hydrogen()));
  }
  
  
  void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
    Register input = ToRegister(instr->value());
    Register result = ToRegister(instr->result());
  
    __ AssertString(input);
  
    __ mov(result, FieldOperand(input, String::kHashFieldOffset));
    __ IndexFromHash(result, result);
  }
  
  
  void LCodeGen::DoHasCachedArrayIndexAndBranch(
      LHasCachedArrayIndexAndBranch* instr) {
    Register input = ToRegister(instr->value());
  
    __ test(FieldOperand(input, String::kHashFieldOffset),
            Immediate(String::kContainsCachedArrayIndexMask));
    EmitBranch(instr, equal);
  }
  
  
  // Branches to a label or falls through with the answer in the z flag.  Trashes
  // the temp registers, but not the input.
  void LCodeGen::EmitClassOfTest(Label* is_true,
                                 Label* is_false,
                                 Handle<String>class_name,
                                 Register input,
                                 Register temp,
                                 Register temp2) {
    ASSERT(!input.is(temp));
    ASSERT(!input.is(temp2));
    ASSERT(!temp.is(temp2));
    __ JumpIfSmi(input, is_false);
  
    if (class_name->IsOneByteEqualTo(STATIC_ASCII_VECTOR("Function"))) {
      // Assuming the following assertions, we can use the same compares to test
      // for both being a function type and being in the object type range.
      STATIC_ASSERT(NUM_OF_CALLABLE_SPEC_OBJECT_TYPES == 2);
      STATIC_ASSERT(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE ==
                    FIRST_SPEC_OBJECT_TYPE + 1);
      STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE ==
                    LAST_SPEC_OBJECT_TYPE - 1);
      STATIC_ASSERT(LAST_SPEC_OBJECT_TYPE == LAST_TYPE);
      __ CmpObjectType(input, FIRST_SPEC_OBJECT_TYPE, temp);
      __ j(below, is_false);
      __ j(equal, is_true);
      __ CmpInstanceType(temp, LAST_SPEC_OBJECT_TYPE);
      __ j(equal, is_true);
    } else {
      // Faster code path to avoid two compares: subtract lower bound from the
      // actual type and do a signed compare with the width of the type range.
      __ mov(temp, FieldOperand(input, HeapObject::kMapOffset));
      __ movzx_b(temp2, FieldOperand(temp, Map::kInstanceTypeOffset));
      __ sub(Operand(temp2), Immediate(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
      __ cmp(Operand(temp2), Immediate(LAST_NONCALLABLE_SPEC_OBJECT_TYPE -
                                       FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
      __ j(above, is_false);
    }
  
    // Now we are in the FIRST-LAST_NONCALLABLE_SPEC_OBJECT_TYPE range.
    // Check if the constructor in the map is a function.
    __ mov(temp, FieldOperand(temp, Map::kConstructorOffset));
    // Objects with a non-function constructor have class 'Object'.
    __ CmpObjectType(temp, JS_FUNCTION_TYPE, temp2);
    if (class_name->IsOneByteEqualTo(STATIC_ASCII_VECTOR("Object"))) {
      __ j(not_equal, is_true);
    } else {
      __ j(not_equal, is_false);
    }
  
    // temp now contains the constructor function. Grab the
    // instance class name from there.
    __ mov(temp, FieldOperand(temp, JSFunction::kSharedFunctionInfoOffset));
    __ mov(temp, FieldOperand(temp,
                              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.
    __ cmp(temp, class_name);
    // End with the answer in the z flag.
  }
  
  
  void LCodeGen::DoClassOfTestAndBranch(LClassOfTestAndBranch* instr) {
    Register input = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
    Register temp2 = ToRegister(instr->temp2());
  
    Handle<String> class_name = instr->hydrogen()->class_name();
  
    EmitClassOfTest(instr->TrueLabel(chunk_), instr->FalseLabel(chunk_),
        class_name, input, temp, temp2);
  
    EmitBranch(instr, equal);
  }
  
  
  void LCodeGen::DoCmpMapAndBranch(LCmpMapAndBranch* instr) {
    Register reg = ToRegister(instr->value());
    __ cmp(FieldOperand(reg, HeapObject::kMapOffset), instr->map());
    EmitBranch(instr, equal);
  }
  
  
  void LCodeGen::DoInstanceOf(LInstanceOf* instr) {
    // Object and function are in fixed registers defined by the stub.
    ASSERT(ToRegister(instr->context()).is(esi));
    InstanceofStub stub(isolate(), InstanceofStub::kArgsInRegisters);
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  
    Label true_value, done;
    __ test(eax, Operand(eax));
    __ j(zero, &true_value, Label::kNear);
    __ mov(ToRegister(instr->result()), factory()->false_value());
    __ jmp(&done, Label::kNear);
    __ bind(&true_value);
    __ mov(ToRegister(instr->result()), factory()->true_value());
    __ bind(&done);
  }
  
  
  void LCodeGen::DoInstanceOfKnownGlobal(LInstanceOfKnownGlobal* instr) {
    class DeferredInstanceOfKnownGlobal V8_FINAL : public LDeferredCode {
     public:
      DeferredInstanceOfKnownGlobal(LCodeGen* codegen,
                                    LInstanceOfKnownGlobal* instr,
                                    const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredInstanceOfKnownGlobal(instr_, &map_check_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
      Label* map_check() { return &map_check_; }
     private:
      LInstanceOfKnownGlobal* instr_;
      Label map_check_;
    };
  
    DeferredInstanceOfKnownGlobal* deferred;
    deferred = new(zone()) DeferredInstanceOfKnownGlobal(this, instr, x87_stack_);
  
    Label done, false_result;
    Register object = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    // A Smi is not an instance of anything.
    __ JumpIfSmi(object, &false_result, Label::kNear);
  
    // This is the inlined call site instanceof cache. The two occurences of the
    // hole value will be patched to the last map/result pair generated by the
    // instanceof stub.
    Label cache_miss;
    Register map = ToRegister(instr->temp());
    __ mov(map, FieldOperand(object, HeapObject::kMapOffset));
    __ bind(deferred->map_check());  // Label for calculating code patching.
    Handle<Cell> cache_cell = factory()->NewCell(factory()->the_hole_value());
    __ cmp(map, Operand::ForCell(cache_cell));  // Patched to cached map.
    __ j(not_equal, &cache_miss, Label::kNear);
    __ mov(eax, factory()->the_hole_value());  // Patched to either true or false.
    __ jmp(&done, Label::kNear);
  
    // The inlined call site cache did not match. Check for null and string
    // before calling the deferred code.
    __ bind(&cache_miss);
    // Null is not an instance of anything.
    __ cmp(object, factory()->null_value());
    __ j(equal, &false_result, Label::kNear);
  
    // String values are not instances of anything.
    Condition is_string = masm_->IsObjectStringType(object, temp, temp);
    __ j(is_string, &false_result, Label::kNear);
  
    // Go to the deferred code.
    __ jmp(deferred->entry());
  
    __ bind(&false_result);
    __ mov(ToRegister(instr->result()), factory()->false_value());
  
    // Here result has either true or false. Deferred code also produces true or
    // false object.
    __ bind(deferred->exit());
    __ bind(&done);
  }
  
  
  void LCodeGen::DoDeferredInstanceOfKnownGlobal(LInstanceOfKnownGlobal* instr,
                                                 Label* map_check) {
    PushSafepointRegistersScope scope(this);
  
    InstanceofStub::Flags flags = InstanceofStub::kNoFlags;
    flags = static_cast<InstanceofStub::Flags>(
        flags | InstanceofStub::kArgsInRegisters);
    flags = static_cast<InstanceofStub::Flags>(
        flags | InstanceofStub::kCallSiteInlineCheck);
    flags = static_cast<InstanceofStub::Flags>(
        flags | InstanceofStub::kReturnTrueFalseObject);
    InstanceofStub stub(isolate(), flags);
  
    // Get the temp register reserved by the instruction. This needs to be a
    // register which is pushed last by PushSafepointRegisters as top of the
    // stack is used to pass the offset to the location of the map check to
    // the stub.
    Register temp = ToRegister(instr->temp());
    ASSERT(MacroAssembler::SafepointRegisterStackIndex(temp) == 0);
    __ LoadHeapObject(InstanceofStub::right(), instr->function());
    static const int kAdditionalDelta = 13;
    int delta = masm_->SizeOfCodeGeneratedSince(map_check) + kAdditionalDelta;
    __ mov(temp, Immediate(delta));
    __ StoreToSafepointRegisterSlot(temp, temp);
    CallCodeGeneric(stub.GetCode(),
                    RelocInfo::CODE_TARGET,
                    instr,
                    RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
    // Get the deoptimization index of the LLazyBailout-environment that
    // corresponds to this instruction.
    LEnvironment* env = instr->GetDeferredLazyDeoptimizationEnvironment();
    safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
  
    // Put the result value into the eax slot and restore all registers.
    __ StoreToSafepointRegisterSlot(eax, eax);
  }
  
  
  void LCodeGen::DoCmpT(LCmpT* instr) {
    Token::Value op = instr->op();
  
    Handle<Code> ic = CompareIC::GetUninitialized(isolate(), op);
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  
    Condition condition = ComputeCompareCondition(op);
    Label true_value, done;
    __ test(eax, Operand(eax));
    __ j(condition, &true_value, Label::kNear);
    __ mov(ToRegister(instr->result()), factory()->false_value());
    __ jmp(&done, Label::kNear);
    __ bind(&true_value);
    __ mov(ToRegister(instr->result()), factory()->true_value());
    __ bind(&done);
  }
  
  
  void LCodeGen::EmitReturn(LReturn* instr, bool dynamic_frame_alignment) {
    int extra_value_count = dynamic_frame_alignment ? 2 : 1;
  
    if (instr->has_constant_parameter_count()) {
      int parameter_count = ToInteger32(instr->constant_parameter_count());
      if (dynamic_frame_alignment && FLAG_debug_code) {
        __ cmp(Operand(esp,
                       (parameter_count + extra_value_count) * kPointerSize),
               Immediate(kAlignmentZapValue));
        __ Assert(equal, kExpectedAlignmentMarker);
      }
      __ Ret((parameter_count + extra_value_count) * kPointerSize, ecx);
    } else {
      Register reg = ToRegister(instr->parameter_count());
      // The argument count parameter is a smi
      __ SmiUntag(reg);
      Register return_addr_reg = reg.is(ecx) ? ebx : ecx;
      if (dynamic_frame_alignment && FLAG_debug_code) {
        ASSERT(extra_value_count == 2);
        __ cmp(Operand(esp, reg, times_pointer_size,
                       extra_value_count * kPointerSize),
               Immediate(kAlignmentZapValue));
        __ Assert(equal, kExpectedAlignmentMarker);
      }
  
      // emit code to restore stack based on instr->parameter_count()
      __ pop(return_addr_reg);  // save return address
      if (dynamic_frame_alignment) {
        __ inc(reg);  // 1 more for alignment
      }
      __ shl(reg, kPointerSizeLog2);
      __ add(esp, reg);
      __ jmp(return_addr_reg);
    }
  }
  
  
  void LCodeGen::DoReturn(LReturn* instr) {
    if (FLAG_trace && info()->IsOptimizing()) {
      // Preserve the return value on the stack and rely on the runtime call
      // to return the value in the same register.  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(eax);
      __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
      __ CallRuntime(Runtime::kTraceExit, 1);
    }
    if (info()->saves_caller_doubles() && CpuFeatures::IsSupported(SSE2)) {
      RestoreCallerDoubles();
    }
    if (dynamic_frame_alignment_) {
      // Fetch the state of the dynamic frame alignment.
      __ mov(edx, Operand(ebp,
        JavaScriptFrameConstants::kDynamicAlignmentStateOffset));
    }
    int no_frame_start = -1;
    if (NeedsEagerFrame()) {
      __ mov(esp, ebp);
      __ pop(ebp);
      no_frame_start = masm_->pc_offset();
    }
    if (dynamic_frame_alignment_) {
      Label no_padding;
      __ cmp(edx, Immediate(kNoAlignmentPadding));
      __ j(equal, &no_padding, Label::kNear);
  
      EmitReturn(instr, true);
      __ bind(&no_padding);
    }
  
    EmitReturn(instr, false);
    if (no_frame_start != -1) {
      info()->AddNoFrameRange(no_frame_start, masm_->pc_offset());
    }
  }
  
  
  void LCodeGen::DoLoadGlobalCell(LLoadGlobalCell* instr) {
    Register result = ToRegister(instr->result());
    __ mov(result, Operand::ForCell(instr->hydrogen()->cell().handle()));
    if (instr->hydrogen()->RequiresHoleCheck()) {
      __ cmp(result, factory()->the_hole_value());
      DeoptimizeIf(equal, instr->environment());
    }
  }
  
  
  void LCodeGen::DoLoadGlobalGeneric(LLoadGlobalGeneric* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->global_object()).is(edx));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    __ mov(ecx, instr->name());
    ContextualMode mode = instr->for_typeof() ? NOT_CONTEXTUAL : CONTEXTUAL;
    Handle<Code> ic = LoadIC::initialize_stub(isolate(), mode);
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
    Register value = ToRegister(instr->value());
    Handle<PropertyCell> cell_handle = instr->hydrogen()->cell().handle();
  
    // If the cell we are storing to contains the hole it could have
    // been deleted from the property dictionary. In that case, we need
    // to update the property details in the property dictionary to mark
    // it as no longer deleted. We deoptimize in that case.
    if (instr->hydrogen()->RequiresHoleCheck()) {
      __ cmp(Operand::ForCell(cell_handle), factory()->the_hole_value());
      DeoptimizeIf(equal, instr->environment());
    }
  
    // Store the value.
    __ mov(Operand::ForCell(cell_handle), value);
    // Cells are always rescanned, so no write barrier here.
  }
  
  
  void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
    Register context = ToRegister(instr->context());
    Register result = ToRegister(instr->result());
    __ mov(result, ContextOperand(context, instr->slot_index()));
  
    if (instr->hydrogen()->RequiresHoleCheck()) {
      __ cmp(result, factory()->the_hole_value());
      if (instr->hydrogen()->DeoptimizesOnHole()) {
        DeoptimizeIf(equal, instr->environment());
      } else {
        Label is_not_hole;
        __ j(not_equal, &is_not_hole, Label::kNear);
        __ mov(result, factory()->undefined_value());
        __ bind(&is_not_hole);
      }
    }
  }
  
  
  void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
    Register context = ToRegister(instr->context());
    Register value = ToRegister(instr->value());
  
    Label skip_assignment;
  
    Operand target = ContextOperand(context, instr->slot_index());
    if (instr->hydrogen()->RequiresHoleCheck()) {
      __ cmp(target, factory()->the_hole_value());
      if (instr->hydrogen()->DeoptimizesOnHole()) {
        DeoptimizeIf(equal, instr->environment());
      } else {
        __ j(not_equal, &skip_assignment, Label::kNear);
      }
    }
  
    __ mov(target, value);
    if (instr->hydrogen()->NeedsWriteBarrier()) {
      SmiCheck check_needed =
          instr->hydrogen()->value()->IsHeapObject()
              ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
      Register temp = ToRegister(instr->temp());
      int offset = Context::SlotOffset(instr->slot_index());
      __ RecordWriteContextSlot(context,
                                offset,
                                value,
                                temp,
                                GetSaveFPRegsMode(isolate()),
                                EMIT_REMEMBERED_SET,
                                check_needed);
    }
  
    __ bind(&skip_assignment);
  }
  
  
  void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
    HObjectAccess access = instr->hydrogen()->access();
    int offset = access.offset();
  
    if (access.IsExternalMemory()) {
      Register result = ToRegister(instr->result());
      MemOperand operand = instr->object()->IsConstantOperand()
          ? MemOperand::StaticVariable(ToExternalReference(
                  LConstantOperand::cast(instr->object())))
          : MemOperand(ToRegister(instr->object()), offset);
      __ Load(result, operand, access.representation());
      return;
    }
  
    Register object = ToRegister(instr->object());
    if (instr->hydrogen()->representation().IsDouble()) {
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister result = ToDoubleRegister(instr->result());
        __ movsd(result, FieldOperand(object, offset));
      } else {
        X87Mov(ToX87Register(instr->result()), FieldOperand(object, offset));
      }
      return;
    }
  
    Register result = ToRegister(instr->result());
    if (!access.IsInobject()) {
      __ mov(result, FieldOperand(object, JSObject::kPropertiesOffset));
      object = result;
    }
    __ Load(result, FieldOperand(object, offset), access.representation());
  }
  
  
  void LCodeGen::EmitPushTaggedOperand(LOperand* operand) {
    ASSERT(!operand->IsDoubleRegister());
    if (operand->IsConstantOperand()) {
      Handle<Object> object = ToHandle(LConstantOperand::cast(operand));
      AllowDeferredHandleDereference smi_check;
      if (object->IsSmi()) {
        __ Push(Handle<Smi>::cast(object));
      } else {
        __ PushHeapObject(Handle<HeapObject>::cast(object));
      }
    } else if (operand->IsRegister()) {
      __ push(ToRegister(operand));
    } else {
      __ push(ToOperand(operand));
    }
  }
  
  
  void LCodeGen::DoLoadNamedGeneric(LLoadNamedGeneric* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->object()).is(edx));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    __ mov(ecx, instr->name());
    Handle<Code> ic = LoadIC::initialize_stub(isolate(), NOT_CONTEXTUAL);
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
    Register function = ToRegister(instr->function());
    Register temp = ToRegister(instr->temp());
    Register result = ToRegister(instr->result());
  
    // Check that the function really is a function.
    __ CmpObjectType(function, JS_FUNCTION_TYPE, result);
    DeoptimizeIf(not_equal, instr->environment());
  
    // Check whether the function has an instance prototype.
    Label non_instance;
    __ test_b(FieldOperand(result, Map::kBitFieldOffset),
              1 << Map::kHasNonInstancePrototype);
    __ j(not_zero, &non_instance, Label::kNear);
  
    // Get the prototype or initial map from the function.
    __ mov(result,
           FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
  
    // Check that the function has a prototype or an initial map.
    __ cmp(Operand(result), Immediate(factory()->the_hole_value()));
    DeoptimizeIf(equal, instr->environment());
  
    // If the function does not have an initial map, we're done.
    Label done;
    __ CmpObjectType(result, MAP_TYPE, temp);
    __ j(not_equal, &done, Label::kNear);
  
    // Get the prototype from the initial map.
    __ mov(result, FieldOperand(result, Map::kPrototypeOffset));
    __ jmp(&done, Label::kNear);
  
    // Non-instance prototype: Fetch prototype from constructor field
    // in the function's map.
    __ bind(&non_instance);
    __ mov(result, FieldOperand(result, Map::kConstructorOffset));
  
    // All done.
    __ bind(&done);
  }
  
  
  void LCodeGen::DoLoadRoot(LLoadRoot* instr) {
    Register result = ToRegister(instr->result());
    __ LoadRoot(result, instr->index());
  }
  
  
  void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
    Register arguments = ToRegister(instr->arguments());
    Register result = ToRegister(instr->result());
    if (instr->length()->IsConstantOperand() &&
        instr->index()->IsConstantOperand()) {
      int const_index = ToInteger32(LConstantOperand::cast(instr->index()));
      int const_length = ToInteger32(LConstantOperand::cast(instr->length()));
      int index = (const_length - const_index) + 1;
      __ mov(result, Operand(arguments, index * kPointerSize));
    } else {
      Register length = ToRegister(instr->length());
      Operand index = ToOperand(instr->index());
      // There are two words between the frame pointer and the last argument.
      // Subtracting from length accounts for one of them add one more.
      __ sub(length, index);
      __ mov(result, Operand(arguments, length, times_4, kPointerSize));
    }
  }
  
  
  void LCodeGen::DoLoadKeyedExternalArray(LLoadKeyed* instr) {
    ElementsKind elements_kind = instr->elements_kind();
    LOperand* key = instr->key();
    if (!key->IsConstantOperand() &&
        ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
                                    elements_kind)) {
      __ SmiUntag(ToRegister(key));
    }
    Operand operand(BuildFastArrayOperand(
        instr->elements(),
        key,
        instr->hydrogen()->key()->representation(),
        elements_kind,
        0,
        instr->additional_index()));
    if (elements_kind == EXTERNAL_FLOAT32_ELEMENTS ||
        elements_kind == FLOAT32_ELEMENTS) {
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister result(ToDoubleRegister(instr->result()));
        __ movss(result, operand);
        __ cvtss2sd(result, result);
      } else {
        X87Mov(ToX87Register(instr->result()), operand, kX87FloatOperand);
      }
    } else if (elements_kind == EXTERNAL_FLOAT64_ELEMENTS ||
               elements_kind == FLOAT64_ELEMENTS) {
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        __ movsd(ToDoubleRegister(instr->result()), operand);
      } else {
        X87Mov(ToX87Register(instr->result()), operand);
      }
    } else {
      Register result(ToRegister(instr->result()));
      switch (elements_kind) {
        case EXTERNAL_INT8_ELEMENTS:
        case INT8_ELEMENTS:
          __ movsx_b(result, operand);
          break;
        case EXTERNAL_UINT8_CLAMPED_ELEMENTS:
        case EXTERNAL_UINT8_ELEMENTS:
        case UINT8_ELEMENTS:
        case UINT8_CLAMPED_ELEMENTS:
          __ movzx_b(result, operand);
          break;
        case EXTERNAL_INT16_ELEMENTS:
        case INT16_ELEMENTS:
          __ movsx_w(result, operand);
          break;
        case EXTERNAL_UINT16_ELEMENTS:
        case UINT16_ELEMENTS:
          __ movzx_w(result, operand);
          break;
        case EXTERNAL_INT32_ELEMENTS:
        case INT32_ELEMENTS:
          __ mov(result, operand);
          break;
        case EXTERNAL_UINT32_ELEMENTS:
        case UINT32_ELEMENTS:
          __ mov(result, operand);
          if (!instr->hydrogen()->CheckFlag(HInstruction::kUint32)) {
            __ test(result, Operand(result));
            DeoptimizeIf(negative, instr->environment());
          }
          break;
        case EXTERNAL_FLOAT32_ELEMENTS:
        case EXTERNAL_FLOAT64_ELEMENTS:
        case FLOAT32_ELEMENTS:
        case FLOAT64_ELEMENTS:
        case FAST_SMI_ELEMENTS:
        case FAST_ELEMENTS:
        case FAST_DOUBLE_ELEMENTS:
        case FAST_HOLEY_SMI_ELEMENTS:
        case FAST_HOLEY_ELEMENTS:
        case FAST_HOLEY_DOUBLE_ELEMENTS:
        case DICTIONARY_ELEMENTS:
        case SLOPPY_ARGUMENTS_ELEMENTS:
          UNREACHABLE();
          break;
      }
    }
  }
  
  
  void LCodeGen::DoLoadKeyedFixedDoubleArray(LLoadKeyed* instr) {
    if (instr->hydrogen()->RequiresHoleCheck()) {
      int offset = FixedDoubleArray::kHeaderSize - kHeapObjectTag +
          sizeof(kHoleNanLower32);
      Operand hole_check_operand = BuildFastArrayOperand(
          instr->elements(), instr->key(),
          instr->hydrogen()->key()->representation(),
          FAST_DOUBLE_ELEMENTS,
          offset,
          instr->additional_index());
      __ cmp(hole_check_operand, Immediate(kHoleNanUpper32));
      DeoptimizeIf(equal, instr->environment());
    }
  
    Operand double_load_operand = BuildFastArrayOperand(
        instr->elements(),
        instr->key(),
        instr->hydrogen()->key()->representation(),
        FAST_DOUBLE_ELEMENTS,
        FixedDoubleArray::kHeaderSize - kHeapObjectTag,
        instr->additional_index());
    if (CpuFeatures::IsSupported(SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister result = ToDoubleRegister(instr->result());
      __ movsd(result, double_load_operand);
    } else {
      X87Mov(ToX87Register(instr->result()), double_load_operand);
    }
  }
  
  
  void LCodeGen::DoLoadKeyedFixedArray(LLoadKeyed* instr) {
    Register result = ToRegister(instr->result());
  
    // Load the result.
    __ mov(result,
           BuildFastArrayOperand(instr->elements(),
                                 instr->key(),
                                 instr->hydrogen()->key()->representation(),
                                 FAST_ELEMENTS,
                                 FixedArray::kHeaderSize - kHeapObjectTag,
                                 instr->additional_index()));
  
    // Check for the hole value.
    if (instr->hydrogen()->RequiresHoleCheck()) {
      if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
        __ test(result, Immediate(kSmiTagMask));
        DeoptimizeIf(not_equal, instr->environment());
      } else {
        __ cmp(result, factory()->the_hole_value());
        DeoptimizeIf(equal, instr->environment());
      }
    }
  }
  
  
  void LCodeGen::DoLoadKeyed(LLoadKeyed* instr) {
    if (instr->is_typed_elements()) {
      DoLoadKeyedExternalArray(instr);
    } else if (instr->hydrogen()->representation().IsDouble()) {
      DoLoadKeyedFixedDoubleArray(instr);
    } else {
      DoLoadKeyedFixedArray(instr);
    }
  }
  
  
  Operand LCodeGen::BuildFastArrayOperand(
      LOperand* elements_pointer,
      LOperand* key,
      Representation key_representation,
      ElementsKind elements_kind,
      uint32_t offset,
      uint32_t additional_index) {
    Register elements_pointer_reg = ToRegister(elements_pointer);
    int element_shift_size = ElementsKindToShiftSize(elements_kind);
    if (IsFixedTypedArrayElementsKind(elements_kind)) {
      offset += FixedTypedArrayBase::kDataOffset - kHeapObjectTag;
    }
    int shift_size = element_shift_size;
    if (key->IsConstantOperand()) {
      int constant_value = ToInteger32(LConstantOperand::cast(key));
      if (constant_value & 0xF0000000) {
        Abort(kArrayIndexConstantValueTooBig);
      }
      return Operand(elements_pointer_reg,
                     ((constant_value + additional_index) << shift_size)
                         + offset);
    } else {
      // Take the tag bit into account while computing the shift size.
      if (key_representation.IsSmi() && (shift_size >= 1)) {
        shift_size -= kSmiTagSize;
      }
      ScaleFactor scale_factor = static_cast<ScaleFactor>(shift_size);
      return Operand(elements_pointer_reg,
                     ToRegister(key),
                     scale_factor,
                     offset + (additional_index << element_shift_size));
    }
  }
  
  
  void LCodeGen::DoLoadKeyedGeneric(LLoadKeyedGeneric* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->object()).is(edx));
    ASSERT(ToRegister(instr->key()).is(ecx));
  
    Handle<Code> ic = isolate()->builtins()->KeyedLoadIC_Initialize();
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoArgumentsElements(LArgumentsElements* instr) {
    Register result = ToRegister(instr->result());
  
    if (instr->hydrogen()->from_inlined()) {
      __ lea(result, Operand(esp, -2 * kPointerSize));
    } else {
      // Check for arguments adapter frame.
      Label done, adapted;
      __ mov(result, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
      __ mov(result, Operand(result, StandardFrameConstants::kContextOffset));
      __ cmp(Operand(result),
             Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
      __ j(equal, &adapted, Label::kNear);
  
      // No arguments adaptor frame.
      __ mov(result, Operand(ebp));
      __ jmp(&done, Label::kNear);
  
      // Arguments adaptor frame present.
      __ bind(&adapted);
      __ mov(result, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
  
      // Result is the frame pointer for the frame if not adapted and for the real
      // frame below the adaptor frame if adapted.
      __ bind(&done);
    }
  }
  
  
  void LCodeGen::DoArgumentsLength(LArgumentsLength* instr) {
    Operand elem = ToOperand(instr->elements());
    Register result = ToRegister(instr->result());
  
    Label done;
  
    // If no arguments adaptor frame the number of arguments is fixed.
    __ cmp(ebp, elem);
    __ mov(result, Immediate(scope()->num_parameters()));
    __ j(equal, &done, Label::kNear);
  
    // Arguments adaptor frame present. Get argument length from there.
    __ mov(result, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
    __ mov(result, Operand(result,
                           ArgumentsAdaptorFrameConstants::kLengthOffset));
    __ SmiUntag(result);
  
    // Argument length is in result register.
    __ bind(&done);
  }
  
  
  void LCodeGen::DoWrapReceiver(LWrapReceiver* instr) {
    Register receiver = ToRegister(instr->receiver());
    Register function = ToRegister(instr->function());
  
    // 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 receiver_ok, global_object;
    Label::Distance dist = DeoptEveryNTimes() ? Label::kFar : Label::kNear;
    Register scratch = ToRegister(instr->temp());
  
    if (!instr->hydrogen()->known_function()) {
      // Do not transform the receiver to object for strict mode
      // functions.
      __ mov(scratch,
             FieldOperand(function, JSFunction::kSharedFunctionInfoOffset));
      __ test_b(FieldOperand(scratch, SharedFunctionInfo::kStrictModeByteOffset),
                1 << SharedFunctionInfo::kStrictModeBitWithinByte);
      __ j(not_equal, &receiver_ok, dist);
  
      // Do not transform the receiver to object for builtins.
      __ test_b(FieldOperand(scratch, SharedFunctionInfo::kNativeByteOffset),
                1 << SharedFunctionInfo::kNativeBitWithinByte);
      __ j(not_equal, &receiver_ok, dist);
    }
  
    // Normal function. Replace undefined or null with global receiver.
    __ cmp(receiver, factory()->null_value());
    __ j(equal, &global_object, Label::kNear);
    __ cmp(receiver, factory()->undefined_value());
    __ j(equal, &global_object, Label::kNear);
  
    // The receiver should be a JS object.
    __ test(receiver, Immediate(kSmiTagMask));
    DeoptimizeIf(equal, instr->environment());
    __ CmpObjectType(receiver, FIRST_SPEC_OBJECT_TYPE, scratch);
    DeoptimizeIf(below, instr->environment());
  
    __ jmp(&receiver_ok, Label::kNear);
    __ bind(&global_object);
    __ mov(receiver, FieldOperand(function, JSFunction::kContextOffset));
    const int global_offset = Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX);
    __ mov(receiver, Operand(receiver, global_offset));
    const int receiver_offset = GlobalObject::kGlobalReceiverOffset;
    __ mov(receiver, FieldOperand(receiver, receiver_offset));
    __ bind(&receiver_ok);
  }
  
  
  void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
    Register receiver = ToRegister(instr->receiver());
    Register function = ToRegister(instr->function());
    Register length = ToRegister(instr->length());
    Register elements = ToRegister(instr->elements());
    ASSERT(receiver.is(eax));  // Used for parameter count.
    ASSERT(function.is(edi));  // Required by InvokeFunction.
    ASSERT(ToRegister(instr->result()).is(eax));
  
    // Copy the arguments to this function possibly from the
    // adaptor frame below it.
    const uint32_t kArgumentsLimit = 1 * KB;
    __ cmp(length, kArgumentsLimit);
    DeoptimizeIf(above, instr->environment());
  
    __ push(receiver);
    __ mov(receiver, length);
  
    // 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.
    __ test(length, Operand(length));
    __ j(zero, &invoke, Label::kNear);
    __ bind(&loop);
    __ push(Operand(elements, length, times_pointer_size, 1 * kPointerSize));
    __ dec(length);
    __ j(not_zero, &loop);
  
    // Invoke the function.
    __ bind(&invoke);
    ASSERT(instr->HasPointerMap());
    LPointerMap* pointers = instr->pointer_map();
    SafepointGenerator safepoint_generator(
        this, pointers, Safepoint::kLazyDeopt);
    ParameterCount actual(eax);
    __ InvokeFunction(function, actual, CALL_FUNCTION, safepoint_generator);
  }
  
  
  void LCodeGen::DoDebugBreak(LDebugBreak* instr) {
    __ int3();
  }
  
  
  void LCodeGen::DoPushArgument(LPushArgument* instr) {
    LOperand* argument = instr->value();
    EmitPushTaggedOperand(argument);
  }
  
  
  void LCodeGen::DoDrop(LDrop* instr) {
    __ Drop(instr->count());
  }
  
  
  void LCodeGen::DoThisFunction(LThisFunction* instr) {
    Register result = ToRegister(instr->result());
    __ mov(result, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
  }
  
  
  void LCodeGen::DoContext(LContext* instr) {
    Register result = ToRegister(instr->result());
    if (info()->IsOptimizing()) {
      __ mov(result, Operand(ebp, StandardFrameConstants::kContextOffset));
    } else {
      // If there is no frame, the context must be in esi.
      ASSERT(result.is(esi));
    }
  }
  
  
  void LCodeGen::DoDeclareGlobals(LDeclareGlobals* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    __ push(esi);  // The context is the first argument.
    __ push(Immediate(instr->hydrogen()->pairs()));
    __ push(Immediate(Smi::FromInt(instr->hydrogen()->flags())));
    CallRuntime(Runtime::kHiddenDeclareGlobals, 3, instr);
  }
  
  
  void LCodeGen::CallKnownFunction(Handle<JSFunction> function,
                                   int formal_parameter_count,
                                   int arity,
                                   LInstruction* instr,
                                   EDIState edi_state) {
    bool dont_adapt_arguments =
        formal_parameter_count == SharedFunctionInfo::kDontAdaptArgumentsSentinel;
    bool can_invoke_directly =
        dont_adapt_arguments || formal_parameter_count == arity;
  
    if (can_invoke_directly) {
      if (edi_state == EDI_UNINITIALIZED) {
        __ LoadHeapObject(edi, function);
      }
  
      // Change context.
      __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
  
      // Set eax to arguments count if adaption is not needed. Assumes that eax
      // is available to write to at this point.
      if (dont_adapt_arguments) {
        __ mov(eax, arity);
      }
  
      // Invoke function directly.
      if (function.is_identical_to(info()->closure())) {
        __ CallSelf();
      } else {
        __ call(FieldOperand(edi, JSFunction::kCodeEntryOffset));
      }
      RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
    } else {
      // We need to adapt arguments.
      LPointerMap* pointers = instr->pointer_map();
      SafepointGenerator generator(
          this, pointers, Safepoint::kLazyDeopt);
      ParameterCount count(arity);
      ParameterCount expected(formal_parameter_count);
      __ InvokeFunction(function, expected, count, CALL_FUNCTION, generator);
    }
  }
  
  
  void LCodeGen::DoCallWithDescriptor(LCallWithDescriptor* instr) {
    ASSERT(ToRegister(instr->result()).is(eax));
  
    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));
      __ call(code, RelocInfo::CODE_TARGET);
    } else {
      ASSERT(instr->target()->IsRegister());
      Register target = ToRegister(instr->target());
      generator.BeforeCall(__ CallSize(Operand(target)));
      __ add(target, Immediate(Code::kHeaderSize - kHeapObjectTag));
      __ call(target);
    }
    generator.AfterCall();
  }
  
  
  void LCodeGen::DoCallJSFunction(LCallJSFunction* instr) {
    ASSERT(ToRegister(instr->function()).is(edi));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    if (instr->hydrogen()->pass_argument_count()) {
      __ mov(eax, instr->arity());
    }
  
    // Change context.
    __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
  
    bool is_self_call = false;
    if (instr->hydrogen()->function()->IsConstant()) {
      HConstant* fun_const = HConstant::cast(instr->hydrogen()->function());
      Handle<JSFunction> jsfun =
        Handle<JSFunction>::cast(fun_const->handle(isolate()));
      is_self_call = jsfun.is_identical_to(info()->closure());
    }
  
    if (is_self_call) {
      __ CallSelf();
    } else {
      __ call(FieldOperand(edi, JSFunction::kCodeEntryOffset));
    }
  
    RecordSafepointWithLazyDeopt(instr, RECORD_SIMPLE_SAFEPOINT);
  }
  
  
  void LCodeGen::DoDeferredMathAbsTaggedHeapNumber(LMathAbs* instr) {
    Register input_reg = ToRegister(instr->value());
    __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
           factory()->heap_number_map());
    DeoptimizeIf(not_equal, instr->environment());
  
    Label slow, allocated, done;
    Register tmp = input_reg.is(eax) ? ecx : eax;
    Register tmp2 = tmp.is(ecx) ? edx : input_reg.is(ecx) ? edx : ecx;
  
    // Preserve the value of all registers.
    PushSafepointRegistersScope scope(this);
  
    __ mov(tmp, FieldOperand(input_reg, HeapNumber::kExponentOffset));
    // Check the sign of the argument. If the argument is positive, just
    // return it. We do not need to patch the stack since |input| and
    // |result| are the same register and |input| will be restored
    // unchanged by popping safepoint registers.
    __ test(tmp, Immediate(HeapNumber::kSignMask));
    __ j(zero, &done, Label::kNear);
  
    __ AllocateHeapNumber(tmp, tmp2, no_reg, &slow);
    __ jmp(&allocated, Label::kNear);
  
    // Slow case: Call the runtime system to do the number allocation.
    __ bind(&slow);
    CallRuntimeFromDeferred(Runtime::kHiddenAllocateHeapNumber, 0,
                            instr, instr->context());
    // Set the pointer to the new heap number in tmp.
    if (!tmp.is(eax)) __ mov(tmp, eax);
    // Restore input_reg after call to runtime.
    __ LoadFromSafepointRegisterSlot(input_reg, input_reg);
  
    __ bind(&allocated);
    __ mov(tmp2, FieldOperand(input_reg, HeapNumber::kExponentOffset));
    __ and_(tmp2, ~HeapNumber::kSignMask);
    __ mov(FieldOperand(tmp, HeapNumber::kExponentOffset), tmp2);
    __ mov(tmp2, FieldOperand(input_reg, HeapNumber::kMantissaOffset));
    __ mov(FieldOperand(tmp, HeapNumber::kMantissaOffset), tmp2);
    __ StoreToSafepointRegisterSlot(input_reg, tmp);
  
    __ bind(&done);
  }
  
  
  void LCodeGen::EmitIntegerMathAbs(LMathAbs* instr) {
    Register input_reg = ToRegister(instr->value());
    __ test(input_reg, Operand(input_reg));
    Label is_positive;
    __ j(not_sign, &is_positive, Label::kNear);
    __ neg(input_reg);  // Sets flags.
    DeoptimizeIf(negative, instr->environment());
    __ bind(&is_positive);
  }
  
  
  void LCodeGen::DoMathAbs(LMathAbs* instr) {
    // Class for deferred case.
    class DeferredMathAbsTaggedHeapNumber V8_FINAL : public LDeferredCode {
     public:
      DeferredMathAbsTaggedHeapNumber(LCodeGen* codegen,
                                      LMathAbs* instr,
                                      const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredMathAbsTaggedHeapNumber(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LMathAbs* instr_;
    };
  
    ASSERT(instr->value()->Equals(instr->result()));
    Representation r = instr->hydrogen()->value()->representation();
  
    CpuFeatureScope scope(masm(), SSE2);
    if (r.IsDouble()) {
      XMMRegister scratch = double_scratch0();
      XMMRegister input_reg = ToDoubleRegister(instr->value());
      __ xorps(scratch, scratch);
      __ subsd(scratch, input_reg);
      __ andps(input_reg, scratch);
    } else if (r.IsSmiOrInteger32()) {
      EmitIntegerMathAbs(instr);
    } else {  // Tagged case.
      DeferredMathAbsTaggedHeapNumber* deferred =
          new(zone()) DeferredMathAbsTaggedHeapNumber(this, instr, x87_stack_);
      Register input_reg = ToRegister(instr->value());
      // Smi check.
      __ JumpIfNotSmi(input_reg, deferred->entry());
      EmitIntegerMathAbs(instr);
      __ bind(deferred->exit());
    }
  }
  
  
  void LCodeGen::DoMathFloor(LMathFloor* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister xmm_scratch = double_scratch0();
    Register output_reg = ToRegister(instr->result());
    XMMRegister input_reg = ToDoubleRegister(instr->value());
  
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope scope(masm(), SSE4_1);
      if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
        // Deoptimize on negative zero.
        Label non_zero;
        __ xorps(xmm_scratch, xmm_scratch);  // Zero the register.
        __ ucomisd(input_reg, xmm_scratch);
        __ j(not_equal, &non_zero, Label::kNear);
        __ movmskpd(output_reg, input_reg);
        __ test(output_reg, Immediate(1));
        DeoptimizeIf(not_zero, instr->environment());
        __ bind(&non_zero);
      }
      __ roundsd(xmm_scratch, input_reg, Assembler::kRoundDown);
      __ cvttsd2si(output_reg, Operand(xmm_scratch));
      // Overflow is signalled with minint.
      __ cmp(output_reg, 0x1);
      DeoptimizeIf(overflow, instr->environment());
    } else {
      Label negative_sign, done;
      // Deoptimize on unordered.
      __ xorps(xmm_scratch, xmm_scratch);  // Zero the register.
      __ ucomisd(input_reg, xmm_scratch);
      DeoptimizeIf(parity_even, instr->environment());
      __ j(below, &negative_sign, Label::kNear);
  
      if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
        // Check for negative zero.
        Label positive_sign;
        __ j(above, &positive_sign, Label::kNear);
        __ movmskpd(output_reg, input_reg);
        __ test(output_reg, Immediate(1));
        DeoptimizeIf(not_zero, instr->environment());
        __ Move(output_reg, Immediate(0));
        __ jmp(&done, Label::kNear);
        __ bind(&positive_sign);
      }
  
      // Use truncating instruction (OK because input is positive).
      __ cvttsd2si(output_reg, Operand(input_reg));
      // Overflow is signalled with minint.
      __ cmp(output_reg, 0x1);
      DeoptimizeIf(overflow, instr->environment());
      __ jmp(&done, Label::kNear);
  
      // Non-zero negative reaches here.
      __ bind(&negative_sign);
      // Truncate, then compare and compensate.
      __ cvttsd2si(output_reg, Operand(input_reg));
      __ Cvtsi2sd(xmm_scratch, output_reg);
      __ ucomisd(input_reg, xmm_scratch);
      __ j(equal, &done, Label::kNear);
      __ sub(output_reg, Immediate(1));
      DeoptimizeIf(overflow, instr->environment());
  
      __ bind(&done);
    }
  }
  
  
  void LCodeGen::DoMathRound(LMathRound* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    Register output_reg = ToRegister(instr->result());
    XMMRegister input_reg = ToDoubleRegister(instr->value());
    XMMRegister xmm_scratch = double_scratch0();
    XMMRegister input_temp = ToDoubleRegister(instr->temp());
    ExternalReference one_half = ExternalReference::address_of_one_half();
    ExternalReference minus_one_half =
        ExternalReference::address_of_minus_one_half();
  
    Label done, round_to_zero, below_one_half, do_not_compensate;
    Label::Distance dist = DeoptEveryNTimes() ? Label::kFar : Label::kNear;
  
    __ movsd(xmm_scratch, Operand::StaticVariable(one_half));
    __ ucomisd(xmm_scratch, input_reg);
    __ j(above, &below_one_half, Label::kNear);
  
    // CVTTSD2SI rounds towards zero, since 0.5 <= x, we use floor(0.5 + x).
    __ addsd(xmm_scratch, input_reg);
    __ cvttsd2si(output_reg, Operand(xmm_scratch));
    // Overflow is signalled with minint.
    __ cmp(output_reg, 0x1);
    __ RecordComment("D2I conversion overflow");
    DeoptimizeIf(overflow, instr->environment());
    __ jmp(&done, dist);
  
    __ bind(&below_one_half);
    __ movsd(xmm_scratch, Operand::StaticVariable(minus_one_half));
    __ ucomisd(xmm_scratch, input_reg);
    __ j(below_equal, &round_to_zero, Label::kNear);
  
    // CVTTSD2SI rounds towards zero, we use ceil(x - (-0.5)) and then
    // compare and compensate.
    __ movaps(input_temp, input_reg);  // Do not alter input_reg.
    __ subsd(input_temp, xmm_scratch);
    __ cvttsd2si(output_reg, Operand(input_temp));
    // Catch minint due to overflow, and to prevent overflow when compensating.
    __ cmp(output_reg, 0x1);
    __ RecordComment("D2I conversion overflow");
    DeoptimizeIf(overflow, instr->environment());
  
    __ Cvtsi2sd(xmm_scratch, output_reg);
    __ ucomisd(xmm_scratch, input_temp);
    __ j(equal, &done, dist);
    __ sub(output_reg, Immediate(1));
    // No overflow because we already ruled out minint.
    __ jmp(&done, dist);
  
    __ bind(&round_to_zero);
    // We return 0 for the input range [+0, 0.5[, or [-0.5, 0.5[ if
    // we can ignore the difference between a result of -0 and +0.
    if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
      // If the sign is positive, we return +0.
      __ movmskpd(output_reg, input_reg);
      __ test(output_reg, Immediate(1));
      __ RecordComment("Minus zero");
      DeoptimizeIf(not_zero, instr->environment());
    }
    __ Move(output_reg, Immediate(0));
    __ bind(&done);
  }
  
  
  void LCodeGen::DoMathSqrt(LMathSqrt* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister input_reg = ToDoubleRegister(instr->value());
    ASSERT(ToDoubleRegister(instr->result()).is(input_reg));
    __ sqrtsd(input_reg, input_reg);
  }
  
  
  void LCodeGen::DoMathPowHalf(LMathPowHalf* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister xmm_scratch = double_scratch0();
    XMMRegister input_reg = ToDoubleRegister(instr->value());
    Register scratch = ToRegister(instr->temp());
    ASSERT(ToDoubleRegister(instr->result()).is(input_reg));
  
    // Note that according to ECMA-262 15.8.2.13:
    // Math.pow(-Infinity, 0.5) == Infinity
    // Math.sqrt(-Infinity) == NaN
    Label done, sqrt;
    // Check base for -Infinity.  According to IEEE-754, single-precision
    // -Infinity has the highest 9 bits set and the lowest 23 bits cleared.
    __ mov(scratch, 0xFF800000);
    __ movd(xmm_scratch, scratch);
    __ cvtss2sd(xmm_scratch, xmm_scratch);
    __ ucomisd(input_reg, xmm_scratch);
    // Comparing -Infinity with NaN results in "unordered", which sets the
    // zero flag as if both were equal.  However, it also sets the carry flag.
    __ j(not_equal, &sqrt, Label::kNear);
    __ j(carry, &sqrt, Label::kNear);
    // If input is -Infinity, return Infinity.
    __ xorps(input_reg, input_reg);
    __ subsd(input_reg, xmm_scratch);
    __ jmp(&done, Label::kNear);
  
    // Square root.
    __ bind(&sqrt);
    __ xorps(xmm_scratch, xmm_scratch);
    __ addsd(input_reg, xmm_scratch);  // Convert -0 to +0.
    __ sqrtsd(input_reg, input_reg);
    __ 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.
    ASSERT(!instr->right()->IsDoubleRegister() ||
           ToDoubleRegister(instr->right()).is(xmm1));
    ASSERT(!instr->right()->IsRegister() ||
           ToRegister(instr->right()).is(eax));
    ASSERT(ToDoubleRegister(instr->left()).is(xmm2));
    ASSERT(ToDoubleRegister(instr->result()).is(xmm3));
  
    if (exponent_type.IsSmi()) {
      MathPowStub stub(isolate(), MathPowStub::TAGGED);
      __ CallStub(&stub);
    } else if (exponent_type.IsTagged()) {
      Label no_deopt;
      __ JumpIfSmi(eax, &no_deopt);
      __ CmpObjectType(eax, HEAP_NUMBER_TYPE, ecx);
      DeoptimizeIf(not_equal, instr->environment());
      __ bind(&no_deopt);
      MathPowStub stub(isolate(), MathPowStub::TAGGED);
      __ CallStub(&stub);
    } else if (exponent_type.IsInteger32()) {
      MathPowStub stub(isolate(), MathPowStub::INTEGER);
      __ CallStub(&stub);
    } else {
      ASSERT(exponent_type.IsDouble());
      MathPowStub stub(isolate(), MathPowStub::DOUBLE);
      __ CallStub(&stub);
    }
  }
  
  
  void LCodeGen::DoMathLog(LMathLog* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    ASSERT(instr->value()->Equals(instr->result()));
    XMMRegister input_reg = ToDoubleRegister(instr->value());
    XMMRegister xmm_scratch = double_scratch0();
    Label positive, done, zero;
    __ xorps(xmm_scratch, xmm_scratch);
    __ ucomisd(input_reg, xmm_scratch);
    __ j(above, &positive, Label::kNear);
    __ j(not_carry, &zero, Label::kNear);
    ExternalReference nan =
        ExternalReference::address_of_canonical_non_hole_nan();
    __ movsd(input_reg, Operand::StaticVariable(nan));
    __ jmp(&done, Label::kNear);
    __ bind(&zero);
    ExternalReference ninf =
        ExternalReference::address_of_negative_infinity();
    __ movsd(input_reg, Operand::StaticVariable(ninf));
    __ jmp(&done, Label::kNear);
    __ bind(&positive);
    __ fldln2();
    __ sub(Operand(esp), Immediate(kDoubleSize));
    __ movsd(Operand(esp, 0), input_reg);
    __ fld_d(Operand(esp, 0));
    __ fyl2x();
    __ fstp_d(Operand(esp, 0));
    __ movsd(input_reg, Operand(esp, 0));
    __ add(Operand(esp), Immediate(kDoubleSize));
    __ bind(&done);
  }
  
  
  void LCodeGen::DoMathClz32(LMathClz32* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    Register input = ToRegister(instr->value());
    Register result = ToRegister(instr->result());
    Label not_zero_input;
    __ bsr(result, input);
  
    __ j(not_zero, &not_zero_input);
    __ Move(result, Immediate(63));  // 63^31 == 32
  
    __ bind(&not_zero_input);
    __ xor_(result, Immediate(31));  // for x in [0..31], 31^x == 31-x.
  }
  
  
  void LCodeGen::DoMathExp(LMathExp* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister input = ToDoubleRegister(instr->value());
    XMMRegister result = ToDoubleRegister(instr->result());
    XMMRegister temp0 = double_scratch0();
    Register temp1 = ToRegister(instr->temp1());
    Register temp2 = ToRegister(instr->temp2());
  
    MathExpGenerator::EmitMathExp(masm(), input, result, temp0, temp1, temp2);
  }
  
  
  void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->function()).is(edi));
    ASSERT(instr->HasPointerMap());
  
    Handle<JSFunction> known_function = instr->hydrogen()->known_function();
    if (known_function.is_null()) {
      LPointerMap* pointers = instr->pointer_map();
      SafepointGenerator generator(
          this, pointers, Safepoint::kLazyDeopt);
      ParameterCount count(instr->arity());
      __ InvokeFunction(edi, count, CALL_FUNCTION, generator);
    } else {
      CallKnownFunction(known_function,
                        instr->hydrogen()->formal_parameter_count(),
                        instr->arity(),
                        instr,
                        EDI_CONTAINS_TARGET);
    }
  }
  
  
  void LCodeGen::DoCallFunction(LCallFunction* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->function()).is(edi));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    int arity = instr->arity();
    CallFunctionStub stub(isolate(), arity, instr->hydrogen()->function_flags());
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoCallNew(LCallNew* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->constructor()).is(edi));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    // No cell in ebx for construct type feedback in optimized code
    __ mov(ebx, isolate()->factory()->undefined_value());
    CallConstructStub stub(isolate(), NO_CALL_CONSTRUCTOR_FLAGS);
    __ Move(eax, Immediate(instr->arity()));
    CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
  }
  
  
  void LCodeGen::DoCallNewArray(LCallNewArray* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->constructor()).is(edi));
    ASSERT(ToRegister(instr->result()).is(eax));
  
    __ Move(eax, Immediate(instr->arity()));
    __ mov(ebx, isolate()->factory()->undefined_value());
    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::CONSTRUCT_CALL, instr);
    } else if (instr->arity() == 1) {
      Label done;
      if (IsFastPackedElementsKind(kind)) {
        Label packed_case;
        // We might need a change here
        // look at the first argument
        __ mov(ecx, Operand(esp, 0));
        __ test(ecx, ecx);
        __ j(zero, &packed_case, Label::kNear);
  
        ElementsKind holey_kind = GetHoleyElementsKind(kind);
        ArraySingleArgumentConstructorStub stub(isolate(),
                                                holey_kind,
                                                override_mode);
        CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
        __ jmp(&done, Label::kNear);
        __ bind(&packed_case);
      }
  
      ArraySingleArgumentConstructorStub stub(isolate(), kind, override_mode);
      CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
      __ bind(&done);
    } else {
      ArrayNArgumentsConstructorStub stub(isolate(), kind, override_mode);
      CallCode(stub.GetCode(), RelocInfo::CONSTRUCT_CALL, instr);
    }
  }
  
  
  void LCodeGen::DoCallRuntime(LCallRuntime* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    CallRuntime(instr->function(), instr->arity(), instr, instr->save_doubles());
  }
  
  
  void LCodeGen::DoStoreCodeEntry(LStoreCodeEntry* instr) {
    Register function = ToRegister(instr->function());
    Register code_object = ToRegister(instr->code_object());
    __ lea(code_object, FieldOperand(code_object, Code::kHeaderSize));
    __ mov(FieldOperand(function, JSFunction::kCodeEntryOffset), code_object);
  }
  
  
  void LCodeGen::DoInnerAllocatedObject(LInnerAllocatedObject* instr) {
    Register result = ToRegister(instr->result());
    Register base = ToRegister(instr->base_object());
    if (instr->offset()->IsConstantOperand()) {
      LConstantOperand* offset = LConstantOperand::cast(instr->offset());
      __ lea(result, Operand(base, ToInteger32(offset)));
    } else {
      Register offset = ToRegister(instr->offset());
      __ lea(result, Operand(base, offset, times_1, 0));
    }
  }
  
  
  void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
    Representation representation = instr->hydrogen()->field_representation();
  
    HObjectAccess access = instr->hydrogen()->access();
    int offset = access.offset();
  
    if (access.IsExternalMemory()) {
      ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
      MemOperand operand = instr->object()->IsConstantOperand()
          ? MemOperand::StaticVariable(
              ToExternalReference(LConstantOperand::cast(instr->object())))
          : MemOperand(ToRegister(instr->object()), offset);
      if (instr->value()->IsConstantOperand()) {
        LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
        __ mov(operand, Immediate(ToInteger32(operand_value)));
      } else {
        Register value = ToRegister(instr->value());
        __ Store(value, operand, representation);
      }
      return;
    }
  
    Register object = ToRegister(instr->object());
    __ AssertNotSmi(object);
  
    ASSERT(!representation.IsSmi() ||
           !instr->value()->IsConstantOperand() ||
           IsSmi(LConstantOperand::cast(instr->value())));
    if (representation.IsDouble()) {
      ASSERT(access.IsInobject());
      ASSERT(!instr->hydrogen()->has_transition());
      ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister value = ToDoubleRegister(instr->value());
        __ movsd(FieldOperand(object, offset), value);
      } else {
        X87Register value = ToX87Register(instr->value());
        X87Mov(FieldOperand(object, offset), value);
      }
      return;
    }
  
    if (instr->hydrogen()->has_transition()) {
      Handle<Map> transition = instr->hydrogen()->transition_map();
      AddDeprecationDependency(transition);
      if (!instr->hydrogen()->NeedsWriteBarrierForMap()) {
        __ mov(FieldOperand(object, HeapObject::kMapOffset), transition);
      } else {
        Register temp = ToRegister(instr->temp());
        Register temp_map = ToRegister(instr->temp_map());
        __ mov(temp_map, transition);
        __ mov(FieldOperand(object, HeapObject::kMapOffset), temp_map);
        // Update the write barrier for the map field.
        __ RecordWriteField(object,
                            HeapObject::kMapOffset,
                            temp_map,
                            temp,
                            GetSaveFPRegsMode(isolate()),
                            OMIT_REMEMBERED_SET,
                            OMIT_SMI_CHECK);
      }
    }
  
    // Do the store.
    Register write_register = object;
    if (!access.IsInobject()) {
      write_register = ToRegister(instr->temp());
      __ mov(write_register, FieldOperand(object, JSObject::kPropertiesOffset));
    }
  
    MemOperand operand = FieldOperand(write_register, offset);
    if (instr->value()->IsConstantOperand()) {
      LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
      if (operand_value->IsRegister()) {
        Register value = ToRegister(operand_value);
        __ Store(value, operand, representation);
      } else if (representation.IsInteger32()) {
        Immediate immediate = ToImmediate(operand_value, representation);
        ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
        __ mov(operand, immediate);
      } else {
        Handle<Object> handle_value = ToHandle(operand_value);
        ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
        __ mov(operand, handle_value);
      }
    } else {
      Register value = ToRegister(instr->value());
      __ Store(value, operand, representation);
    }
  
    if (instr->hydrogen()->NeedsWriteBarrier()) {
      Register value = ToRegister(instr->value());
      Register temp = access.IsInobject() ? ToRegister(instr->temp()) : object;
      // Update the write barrier for the object for in-object properties.
      __ RecordWriteField(write_register,
                          offset,
                          value,
                          temp,
                          GetSaveFPRegsMode(isolate()),
                          EMIT_REMEMBERED_SET,
                          instr->hydrogen()->SmiCheckForWriteBarrier());
    }
  }
  
  
  void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->object()).is(edx));
    ASSERT(ToRegister(instr->value()).is(eax));
  
    __ mov(ecx, instr->name());
    Handle<Code> ic = StoreIC::initialize_stub(isolate(), instr->strict_mode());
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
    Condition cc = instr->hydrogen()->allow_equality() ? above : above_equal;
    if (instr->index()->IsConstantOperand()) {
      __ cmp(ToOperand(instr->length()),
             ToImmediate(LConstantOperand::cast(instr->index()),
                         instr->hydrogen()->length()->representation()));
      cc = ReverseCondition(cc);
    } else if (instr->length()->IsConstantOperand()) {
      __ cmp(ToOperand(instr->index()),
             ToImmediate(LConstantOperand::cast(instr->length()),
                         instr->hydrogen()->index()->representation()));
    } else {
      __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
    }
    if (FLAG_debug_code && instr->hydrogen()->skip_check()) {
      Label done;
      __ j(NegateCondition(cc), &done, Label::kNear);
      __ int3();
      __ bind(&done);
    } else {
      DeoptimizeIf(cc, instr->environment());
    }
  }
  
  
  void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
    ElementsKind elements_kind = instr->elements_kind();
    LOperand* key = instr->key();
    if (!key->IsConstantOperand() &&
        ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
                                    elements_kind)) {
      __ SmiUntag(ToRegister(key));
    }
    Operand operand(BuildFastArrayOperand(
        instr->elements(),
        key,
        instr->hydrogen()->key()->representation(),
        elements_kind,
        0,
        instr->additional_index()));
    if (elements_kind == EXTERNAL_FLOAT32_ELEMENTS ||
        elements_kind == FLOAT32_ELEMENTS) {
      if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister xmm_scratch = double_scratch0();
        __ cvtsd2ss(xmm_scratch, ToDoubleRegister(instr->value()));
        __ movss(operand, xmm_scratch);
      } else {
        __ fld(0);
        __ fstp_s(operand);
      }
    } else if (elements_kind == EXTERNAL_FLOAT64_ELEMENTS ||
               elements_kind == FLOAT64_ELEMENTS) {
      if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        __ movsd(operand, ToDoubleRegister(instr->value()));
      } else {
        X87Mov(operand, ToX87Register(instr->value()));
      }
    } else {
      Register value = ToRegister(instr->value());
      switch (elements_kind) {
        case EXTERNAL_UINT8_CLAMPED_ELEMENTS:
        case EXTERNAL_UINT8_ELEMENTS:
        case EXTERNAL_INT8_ELEMENTS:
        case UINT8_ELEMENTS:
        case INT8_ELEMENTS:
        case UINT8_CLAMPED_ELEMENTS:
          __ mov_b(operand, value);
          break;
        case EXTERNAL_INT16_ELEMENTS:
        case EXTERNAL_UINT16_ELEMENTS:
        case UINT16_ELEMENTS:
        case INT16_ELEMENTS:
          __ mov_w(operand, value);
          break;
        case EXTERNAL_INT32_ELEMENTS:
        case EXTERNAL_UINT32_ELEMENTS:
        case UINT32_ELEMENTS:
        case INT32_ELEMENTS:
          __ mov(operand, value);
          break;
        case EXTERNAL_FLOAT32_ELEMENTS:
        case EXTERNAL_FLOAT64_ELEMENTS:
        case FLOAT32_ELEMENTS:
        case FLOAT64_ELEMENTS:
        case FAST_SMI_ELEMENTS:
        case FAST_ELEMENTS:
        case FAST_DOUBLE_ELEMENTS:
        case FAST_HOLEY_SMI_ELEMENTS:
        case FAST_HOLEY_ELEMENTS:
        case FAST_HOLEY_DOUBLE_ELEMENTS:
        case DICTIONARY_ELEMENTS:
        case SLOPPY_ARGUMENTS_ELEMENTS:
          UNREACHABLE();
          break;
      }
    }
  }
  
  
  void LCodeGen::DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr) {
    ExternalReference canonical_nan_reference =
        ExternalReference::address_of_canonical_non_hole_nan();
    Operand double_store_operand = BuildFastArrayOperand(
        instr->elements(),
        instr->key(),
        instr->hydrogen()->key()->representation(),
        FAST_DOUBLE_ELEMENTS,
        FixedDoubleArray::kHeaderSize - kHeapObjectTag,
        instr->additional_index());
  
    if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister value = ToDoubleRegister(instr->value());
  
      if (instr->NeedsCanonicalization()) {
        Label have_value;
  
        __ ucomisd(value, value);
        __ j(parity_odd, &have_value, Label::kNear);  // NaN.
  
        __ movsd(value, Operand::StaticVariable(canonical_nan_reference));
        __ bind(&have_value);
      }
  
      __ movsd(double_store_operand, value);
    } else {
      // Can't use SSE2 in the serializer
      if (instr->hydrogen()->IsConstantHoleStore()) {
        // This means we should store the (double) hole. No floating point
        // registers required.
        double nan_double = FixedDoubleArray::hole_nan_as_double();
        uint64_t int_val = BitCast<uint64_t, double>(nan_double);
        int32_t lower = static_cast<int32_t>(int_val);
        int32_t upper = static_cast<int32_t>(int_val >> (kBitsPerInt));
  
        __ mov(double_store_operand, Immediate(lower));
        Operand double_store_operand2 = BuildFastArrayOperand(
            instr->elements(),
            instr->key(),
            instr->hydrogen()->key()->representation(),
            FAST_DOUBLE_ELEMENTS,
            FixedDoubleArray::kHeaderSize - kHeapObjectTag + kPointerSize,
            instr->additional_index());
        __ mov(double_store_operand2, Immediate(upper));
      } else {
        Label no_special_nan_handling;
        X87Register value = ToX87Register(instr->value());
        X87Fxch(value);
  
        if (instr->NeedsCanonicalization()) {
          __ fld(0);
          __ fld(0);
          __ FCmp();
  
          __ j(parity_odd, &no_special_nan_handling, Label::kNear);
          __ sub(esp, Immediate(kDoubleSize));
          __ fst_d(MemOperand(esp, 0));
          __ cmp(MemOperand(esp, sizeof(kHoleNanLower32)),
                 Immediate(kHoleNanUpper32));
          __ add(esp, Immediate(kDoubleSize));
          Label canonicalize;
          __ j(not_equal, &canonicalize, Label::kNear);
          __ jmp(&no_special_nan_handling, Label::kNear);
          __ bind(&canonicalize);
          __ fstp(0);
          __ fld_d(Operand::StaticVariable(canonical_nan_reference));
        }
  
        __ bind(&no_special_nan_handling);
        __ fst_d(double_store_operand);
      }
    }
  }
  
  
  void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed* instr) {
    Register elements = ToRegister(instr->elements());
    Register key = instr->key()->IsRegister() ? ToRegister(instr->key()) : no_reg;
  
    Operand operand = BuildFastArrayOperand(
        instr->elements(),
        instr->key(),
        instr->hydrogen()->key()->representation(),
        FAST_ELEMENTS,
        FixedArray::kHeaderSize - kHeapObjectTag,
        instr->additional_index());
    if (instr->value()->IsRegister()) {
      __ mov(operand, ToRegister(instr->value()));
    } else {
      LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
      if (IsSmi(operand_value)) {
        Immediate immediate = ToImmediate(operand_value, Representation::Smi());
        __ mov(operand, immediate);
      } else {
        ASSERT(!IsInteger32(operand_value));
        Handle<Object> handle_value = ToHandle(operand_value);
        __ mov(operand, handle_value);
      }
    }
  
    if (instr->hydrogen()->NeedsWriteBarrier()) {
      ASSERT(instr->value()->IsRegister());
      Register value = ToRegister(instr->value());
      ASSERT(!instr->key()->IsConstantOperand());
      SmiCheck check_needed =
          instr->hydrogen()->value()->IsHeapObject()
            ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
      // Compute address of modified element and store it into key register.
      __ lea(key, operand);
      __ RecordWrite(elements,
                     key,
                     value,
                     GetSaveFPRegsMode(isolate()),
                     EMIT_REMEMBERED_SET,
                     check_needed);
    }
  }
  
  
  void LCodeGen::DoStoreKeyed(LStoreKeyed* instr) {
    // By cases...external, fast-double, fast
    if (instr->is_typed_elements()) {
      DoStoreKeyedExternalArray(instr);
    } else if (instr->hydrogen()->value()->representation().IsDouble()) {
      DoStoreKeyedFixedDoubleArray(instr);
    } else {
      DoStoreKeyedFixedArray(instr);
    }
  }
  
  
  void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->object()).is(edx));
    ASSERT(ToRegister(instr->key()).is(ecx));
    ASSERT(ToRegister(instr->value()).is(eax));
  
    Handle<Code> ic = instr->strict_mode() == STRICT
        ? isolate()->builtins()->KeyedStoreIC_Initialize_Strict()
        : isolate()->builtins()->KeyedStoreIC_Initialize();
    CallCode(ic, RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
    Register object = ToRegister(instr->object());
    Register temp = ToRegister(instr->temp());
    Label no_memento_found;
    __ TestJSArrayForAllocationMemento(object, temp, &no_memento_found);
    DeoptimizeIf(equal, instr->environment());
    __ bind(&no_memento_found);
  }
  
  
  void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
    Register object_reg = 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;
    bool is_simple_map_transition =
        IsSimpleMapChangeTransition(from_kind, to_kind);
    Label::Distance branch_distance =
        is_simple_map_transition ? Label::kNear : Label::kFar;
    __ cmp(FieldOperand(object_reg, HeapObject::kMapOffset), from_map);
    __ j(not_equal, &not_applicable, branch_distance);
    if (is_simple_map_transition) {
      Register new_map_reg = ToRegister(instr->new_map_temp());
      __ mov(FieldOperand(object_reg, HeapObject::kMapOffset),
             Immediate(to_map));
      // Write barrier.
      ASSERT_NE(instr->temp(), NULL);
      __ RecordWriteForMap(object_reg, to_map, new_map_reg,
                           ToRegister(instr->temp()),
                           kDontSaveFPRegs);
    } else {
      ASSERT(ToRegister(instr->context()).is(esi));
      ASSERT(object_reg.is(eax));
      PushSafepointRegistersScope scope(this);
      __ mov(ebx, to_map);
      bool is_js_array = from_map->instance_type() == JS_ARRAY_TYPE;
      TransitionElementsKindStub stub(isolate(), from_kind, to_kind, is_js_array);
      __ CallStub(&stub);
      RecordSafepointWithLazyDeopt(instr,
          RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
    }
    __ bind(&not_applicable);
  }
  
  
  void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
    class DeferredStringCharCodeAt V8_FINAL : public LDeferredCode {
     public:
      DeferredStringCharCodeAt(LCodeGen* codegen,
                               LStringCharCodeAt* instr,
                               const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredStringCharCodeAt(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LStringCharCodeAt* instr_;
    };
  
    DeferredStringCharCodeAt* deferred =
        new(zone()) DeferredStringCharCodeAt(this, instr, x87_stack_);
  
    StringCharLoadGenerator::Generate(masm(),
                                      factory(),
                                      ToRegister(instr->string()),
                                      ToRegister(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.
    __ Move(result, Immediate(0));
  
    PushSafepointRegistersScope scope(this);
    __ push(string);
    // Push the index as a smi. This is safe because of the checks in
    // DoStringCharCodeAt above.
    STATIC_ASSERT(String::kMaxLength <= Smi::kMaxValue);
    if (instr->index()->IsConstantOperand()) {
      Immediate immediate = ToImmediate(LConstantOperand::cast(instr->index()),
                                        Representation::Smi());
      __ push(immediate);
    } else {
      Register index = ToRegister(instr->index());
      __ SmiTag(index);
      __ push(index);
    }
    CallRuntimeFromDeferred(Runtime::kHiddenStringCharCodeAt, 2,
                            instr, instr->context());
    __ AssertSmi(eax);
    __ SmiUntag(eax);
    __ StoreToSafepointRegisterSlot(result, eax);
  }
  
  
  void LCodeGen::DoStringCharFromCode(LStringCharFromCode* instr) {
    class DeferredStringCharFromCode V8_FINAL : public LDeferredCode {
     public:
      DeferredStringCharFromCode(LCodeGen* codegen,
                                 LStringCharFromCode* instr,
                                 const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredStringCharFromCode(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LStringCharFromCode* instr_;
    };
  
    DeferredStringCharFromCode* deferred =
        new(zone()) DeferredStringCharFromCode(this, instr, x87_stack_);
  
    ASSERT(instr->hydrogen()->value()->representation().IsInteger32());
    Register char_code = ToRegister(instr->char_code());
    Register result = ToRegister(instr->result());
    ASSERT(!char_code.is(result));
  
    __ cmp(char_code, String::kMaxOneByteCharCode);
    __ j(above, deferred->entry());
    __ Move(result, Immediate(factory()->single_character_string_cache()));
    __ mov(result, FieldOperand(result,
                                char_code, times_pointer_size,
                                FixedArray::kHeaderSize));
    __ cmp(result, factory()->undefined_value());
    __ j(equal, 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.
    __ Move(result, Immediate(0));
  
    PushSafepointRegistersScope scope(this);
    __ SmiTag(char_code);
    __ push(char_code);
    CallRuntimeFromDeferred(Runtime::kCharFromCode, 1, instr, instr->context());
    __ StoreToSafepointRegisterSlot(result, eax);
  }
  
  
  void LCodeGen::DoStringAdd(LStringAdd* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    ASSERT(ToRegister(instr->left()).is(edx));
    ASSERT(ToRegister(instr->right()).is(eax));
    StringAddStub stub(isolate(),
                       instr->hydrogen()->flags(),
                       instr->hydrogen()->pretenure_flag());
    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
  }
  
  
  void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
    LOperand* input = instr->value();
    LOperand* output = instr->result();
    ASSERT(input->IsRegister() || input->IsStackSlot());
    ASSERT(output->IsDoubleRegister());
    if (CpuFeatures::IsSupported(SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      __ Cvtsi2sd(ToDoubleRegister(output), ToOperand(input));
    } else if (input->IsRegister()) {
      Register input_reg = ToRegister(input);
      __ push(input_reg);
      X87Mov(ToX87Register(output), Operand(esp, 0), kX87IntOperand);
      __ pop(input_reg);
    } else {
      X87Mov(ToX87Register(output), ToOperand(input), kX87IntOperand);
    }
  }
  
  
  void LCodeGen::DoUint32ToDouble(LUint32ToDouble* instr) {
    LOperand* input = instr->value();
    LOperand* output = instr->result();
    if (CpuFeatures::IsSupported(SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      LOperand* temp = instr->temp();
  
      __ LoadUint32(ToDoubleRegister(output),
                    ToRegister(input),
                    ToDoubleRegister(temp));
    } else {
      X87Register res = ToX87Register(output);
      X87PrepareToWrite(res);
      __ LoadUint32NoSSE2(ToRegister(input));
      X87CommitWrite(res);
    }
  }
  
  
  void LCodeGen::DoNumberTagI(LNumberTagI* instr) {
    class DeferredNumberTagI V8_FINAL : public LDeferredCode {
     public:
      DeferredNumberTagI(LCodeGen* codegen,
                         LNumberTagI* instr,
                         const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredNumberTagIU(instr_, instr_->value(), instr_->temp(),
                                         NULL, SIGNED_INT32);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LNumberTagI* instr_;
    };
  
    LOperand* input = instr->value();
    ASSERT(input->IsRegister() && input->Equals(instr->result()));
    Register reg = ToRegister(input);
  
    DeferredNumberTagI* deferred =
        new(zone()) DeferredNumberTagI(this, instr, x87_stack_);
    __ SmiTag(reg);
    __ j(overflow, deferred->entry());
    __ bind(deferred->exit());
  }
  
  
  void LCodeGen::DoNumberTagU(LNumberTagU* instr) {
    class DeferredNumberTagU V8_FINAL : public LDeferredCode {
     public:
      DeferredNumberTagU(LCodeGen* codegen,
                         LNumberTagU* instr,
                         const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredNumberTagIU(instr_, instr_->value(), instr_->temp1(),
                                         instr_->temp2(), UNSIGNED_INT32);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LNumberTagU* instr_;
    };
  
    LOperand* input = instr->value();
    ASSERT(input->IsRegister() && input->Equals(instr->result()));
    Register reg = ToRegister(input);
  
    DeferredNumberTagU* deferred =
        new(zone()) DeferredNumberTagU(this, instr, x87_stack_);
    __ cmp(reg, Immediate(Smi::kMaxValue));
    __ j(above, deferred->entry());
    __ SmiTag(reg);
    __ bind(deferred->exit());
  }
  
  
  void LCodeGen::DoDeferredNumberTagIU(LInstruction* instr,
                                       LOperand* value,
                                       LOperand* temp1,
                                       LOperand* temp2,
                                       IntegerSignedness signedness) {
    Label done, slow;
    Register reg = ToRegister(value);
    Register tmp = ToRegister(temp1);
    XMMRegister xmm_scratch = double_scratch0();
  
    if (signedness == SIGNED_INT32) {
      // There was overflow, so bits 30 and 31 of the original integer
      // disagree. Try to allocate a heap number in new space and store
      // the value in there. If that fails, call the runtime system.
      __ SmiUntag(reg);
      __ xor_(reg, 0x80000000);
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope feature_scope(masm(), SSE2);
        __ Cvtsi2sd(xmm_scratch, Operand(reg));
      } else {
        __ push(reg);
        __ fild_s(Operand(esp, 0));
        __ pop(reg);
      }
    } else {
      if (CpuFeatures::IsSupported(SSE2)) {
        CpuFeatureScope feature_scope(masm(), SSE2);
        __ LoadUint32(xmm_scratch, reg, ToDoubleRegister(temp2));
      } else {
        // There's no fild variant for unsigned values, so zero-extend to a 64-bit
        // int manually.
        __ push(Immediate(0));
        __ push(reg);
        __ fild_d(Operand(esp, 0));
        __ pop(reg);
        __ pop(reg);
      }
    }
  
    if (FLAG_inline_new) {
      __ AllocateHeapNumber(reg, tmp, no_reg, &slow);
      __ jmp(&done, Label::kNear);
    }
  
    // 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.
      __ Move(reg, Immediate(0));
  
      // Preserve the value of all registers.
      PushSafepointRegistersScope scope(this);
  
      // NumberTagI and NumberTagD use the context from the frame, rather than
      // the environment's HContext or HInlinedContext value.
      // They only call Runtime::kHiddenAllocateHeapNumber.
      // The corresponding HChange instructions are added in a phase that does
      // not have easy access to the local context.
      __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
      __ CallRuntimeSaveDoubles(Runtime::kHiddenAllocateHeapNumber);
      RecordSafepointWithRegisters(
          instr->pointer_map(), 0, Safepoint::kNoLazyDeopt);
      __ StoreToSafepointRegisterSlot(reg, eax);
    }
  
    // Done. Put the value in xmm_scratch into the value of the allocated heap
    // number.
    __ bind(&done);
    if (CpuFeatures::IsSupported(SSE2)) {
      CpuFeatureScope feature_scope(masm(), SSE2);
      __ movsd(FieldOperand(reg, HeapNumber::kValueOffset), xmm_scratch);
    } else {
      __ fstp_d(FieldOperand(reg, HeapNumber::kValueOffset));
    }
  }
  
  
  void LCodeGen::DoNumberTagD(LNumberTagD* instr) {
    class DeferredNumberTagD V8_FINAL : public LDeferredCode {
     public:
      DeferredNumberTagD(LCodeGen* codegen,
                         LNumberTagD* instr,
                         const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredNumberTagD(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LNumberTagD* instr_;
    };
  
    Register reg = ToRegister(instr->result());
  
    bool use_sse2 = CpuFeatures::IsSupported(SSE2);
    if (!use_sse2) {
      // Put the value to the top of stack
      X87Register src = ToX87Register(instr->value());
      X87LoadForUsage(src);
    }
  
    DeferredNumberTagD* deferred =
        new(zone()) DeferredNumberTagD(this, instr, x87_stack_);
    if (FLAG_inline_new) {
      Register tmp = ToRegister(instr->temp());
      __ AllocateHeapNumber(reg, tmp, no_reg, deferred->entry());
    } else {
      __ jmp(deferred->entry());
    }
    __ bind(deferred->exit());
    if (use_sse2) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister input_reg = ToDoubleRegister(instr->value());
      __ movsd(FieldOperand(reg, HeapNumber::kValueOffset), input_reg);
    } else {
      __ fstp_d(FieldOperand(reg, HeapNumber::kValueOffset));
    }
  }
  
  
  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 reg = ToRegister(instr->result());
    __ Move(reg, Immediate(0));
  
    PushSafepointRegistersScope scope(this);
    // NumberTagI and NumberTagD use the context from the frame, rather than
    // the environment's HContext or HInlinedContext value.
    // They only call Runtime::kHiddenAllocateHeapNumber.
    // The corresponding HChange instructions are added in a phase that does
    // not have easy access to the local context.
    __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
    __ CallRuntimeSaveDoubles(Runtime::kHiddenAllocateHeapNumber);
    RecordSafepointWithRegisters(
        instr->pointer_map(), 0, Safepoint::kNoLazyDeopt);
    __ StoreToSafepointRegisterSlot(reg, eax);
  }
  
  
  void LCodeGen::DoSmiTag(LSmiTag* instr) {
    HChange* hchange = instr->hydrogen();
    Register input = ToRegister(instr->value());
    if (hchange->CheckFlag(HValue::kCanOverflow) &&
        hchange->value()->CheckFlag(HValue::kUint32)) {
      __ test(input, Immediate(0xc0000000));
      DeoptimizeIf(not_zero, instr->environment());
    }
    __ SmiTag(input);
    if (hchange->CheckFlag(HValue::kCanOverflow) &&
        !hchange->value()->CheckFlag(HValue::kUint32)) {
      DeoptimizeIf(overflow, instr->environment());
    }
  }
  
  
  void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
    LOperand* input = instr->value();
    Register result = ToRegister(input);
    ASSERT(input->IsRegister() && input->Equals(instr->result()));
    if (instr->needs_check()) {
      __ test(result, Immediate(kSmiTagMask));
      DeoptimizeIf(not_zero, instr->environment());
    } else {
      __ AssertSmi(result);
    }
    __ SmiUntag(result);
  }
  
  
  void LCodeGen::EmitNumberUntagDNoSSE2(Register input_reg,
                                        Register temp_reg,
                                        X87Register res_reg,
                                        bool can_convert_undefined_to_nan,
                                        bool deoptimize_on_minus_zero,
                                        LEnvironment* env,
                                        NumberUntagDMode mode) {
    Label load_smi, done;
  
    X87PrepareToWrite(res_reg);
    if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
      // Smi check.
      __ JumpIfSmi(input_reg, &load_smi, Label::kNear);
  
      // Heap number map check.
      __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
             factory()->heap_number_map());
      if (!can_convert_undefined_to_nan) {
        DeoptimizeIf(not_equal, env);
      } else {
        Label heap_number, convert;
        __ j(equal, &heap_number, Label::kNear);
  
        // Convert undefined (or hole) to NaN.
        __ cmp(input_reg, factory()->undefined_value());
        DeoptimizeIf(not_equal, env);
  
        __ bind(&convert);
        ExternalReference nan =
            ExternalReference::address_of_canonical_non_hole_nan();
        __ fld_d(Operand::StaticVariable(nan));
        __ jmp(&done, Label::kNear);
  
        __ bind(&heap_number);
      }
      // Heap number to x87 conversion.
      __ fld_d(FieldOperand(input_reg, HeapNumber::kValueOffset));
      if (deoptimize_on_minus_zero) {
        __ fldz();
        __ FCmp();
        __ fld_d(FieldOperand(input_reg, HeapNumber::kValueOffset));
        __ j(not_zero, &done, Label::kNear);
  
        // Use general purpose registers to check if we have -0.0
        __ mov(temp_reg, FieldOperand(input_reg, HeapNumber::kExponentOffset));
        __ test(temp_reg, Immediate(HeapNumber::kSignMask));
        __ j(zero, &done, Label::kNear);
  
        // Pop FPU stack before deoptimizing.
        __ fstp(0);
        DeoptimizeIf(not_zero, env);
      }
      __ jmp(&done, Label::kNear);
    } else {
      ASSERT(mode == NUMBER_CANDIDATE_IS_SMI);
    }
  
    __ bind(&load_smi);
    // Clobbering a temp is faster than re-tagging the
    // input register since we avoid dependencies.
    __ mov(temp_reg, input_reg);
    __ SmiUntag(temp_reg);  // Untag smi before converting to float.
    __ push(temp_reg);
    __ fild_s(Operand(esp, 0));
    __ add(esp, Immediate(kPointerSize));
    __ bind(&done);
    X87CommitWrite(res_reg);
  }
  
  
  void LCodeGen::EmitNumberUntagD(Register input_reg,
                                  Register temp_reg,
                                  XMMRegister result_reg,
                                  bool can_convert_undefined_to_nan,
                                  bool deoptimize_on_minus_zero,
                                  LEnvironment* env,
                                  NumberUntagDMode mode) {
    Label convert, load_smi, done;
  
    if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
      // Smi check.
      __ JumpIfSmi(input_reg, &load_smi, Label::kNear);
  
      // Heap number map check.
      __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
             factory()->heap_number_map());
      if (can_convert_undefined_to_nan) {
        __ j(not_equal, &convert, Label::kNear);
      } else {
        DeoptimizeIf(not_equal, env);
      }
  
      // Heap number to XMM conversion.
      __ movsd(result_reg, FieldOperand(input_reg, HeapNumber::kValueOffset));
  
      if (deoptimize_on_minus_zero) {
        XMMRegister xmm_scratch = double_scratch0();
        __ xorps(xmm_scratch, xmm_scratch);
        __ ucomisd(result_reg, xmm_scratch);
        __ j(not_zero, &done, Label::kNear);
        __ movmskpd(temp_reg, result_reg);
        __ test_b(temp_reg, 1);
        DeoptimizeIf(not_zero, env);
      }
      __ jmp(&done, Label::kNear);
  
      if (can_convert_undefined_to_nan) {
        __ bind(&convert);
  
        // Convert undefined (and hole) to NaN.
        __ cmp(input_reg, factory()->undefined_value());
        DeoptimizeIf(not_equal, env);
  
        ExternalReference nan =
            ExternalReference::address_of_canonical_non_hole_nan();
        __ movsd(result_reg, Operand::StaticVariable(nan));
        __ jmp(&done, Label::kNear);
      }
    } else {
      ASSERT(mode == NUMBER_CANDIDATE_IS_SMI);
    }
  
    __ bind(&load_smi);
    // Smi to XMM conversion. Clobbering a temp is faster than re-tagging the
    // input register since we avoid dependencies.
    __ mov(temp_reg, input_reg);
    __ SmiUntag(temp_reg);  // Untag smi before converting to float.
    __ Cvtsi2sd(result_reg, Operand(temp_reg));
    __ bind(&done);
  }
  
  
  void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr, Label* done) {
    Register input_reg = ToRegister(instr->value());
  
    // The input was optimistically untagged; revert it.
    STATIC_ASSERT(kSmiTagSize == 1);
    __ lea(input_reg, Operand(input_reg, times_2, kHeapObjectTag));
  
    if (instr->truncating()) {
      Label no_heap_number, check_bools, check_false;
  
      // Heap number map check.
      __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
             factory()->heap_number_map());
      __ j(not_equal, &no_heap_number, Label::kNear);
      __ TruncateHeapNumberToI(input_reg, input_reg);
      __ jmp(done);
  
      __ bind(&no_heap_number);
      // Check for Oddballs. Undefined/False is converted to zero and True to one
      // for truncating conversions.
      __ cmp(input_reg, factory()->undefined_value());
      __ j(not_equal, &check_bools, Label::kNear);
      __ Move(input_reg, Immediate(0));
      __ jmp(done);
  
      __ bind(&check_bools);
      __ cmp(input_reg, factory()->true_value());
      __ j(not_equal, &check_false, Label::kNear);
      __ Move(input_reg, Immediate(1));
      __ jmp(done);
  
      __ bind(&check_false);
      __ cmp(input_reg, factory()->false_value());
      __ RecordComment("Deferred TaggedToI: cannot truncate");
      DeoptimizeIf(not_equal, instr->environment());
      __ Move(input_reg, Immediate(0));
    } else {
      Label bailout;
      XMMRegister scratch = (instr->temp() != NULL)
          ? ToDoubleRegister(instr->temp())
          : no_xmm_reg;
      __ TaggedToI(input_reg, input_reg, scratch,
                   instr->hydrogen()->GetMinusZeroMode(), &bailout);
      __ jmp(done);
      __ bind(&bailout);
      DeoptimizeIf(no_condition, instr->environment());
    }
  }
  
  
  void LCodeGen::DoTaggedToI(LTaggedToI* instr) {
    class DeferredTaggedToI V8_FINAL : public LDeferredCode {
     public:
      DeferredTaggedToI(LCodeGen* codegen,
                        LTaggedToI* instr,
                        const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredTaggedToI(instr_, done());
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LTaggedToI* instr_;
    };
  
    LOperand* input = instr->value();
    ASSERT(input->IsRegister());
    Register input_reg = ToRegister(input);
    ASSERT(input_reg.is(ToRegister(instr->result())));
  
    if (instr->hydrogen()->value()->representation().IsSmi()) {
      __ SmiUntag(input_reg);
    } else {
      DeferredTaggedToI* deferred =
          new(zone()) DeferredTaggedToI(this, instr, x87_stack_);
      // Optimistically untag the input.
      // If the input is a HeapObject, SmiUntag will set the carry flag.
      STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
      __ SmiUntag(input_reg);
      // Branch to deferred code if the input was tagged.
      // The deferred code will take care of restoring the tag.
      __ j(carry, deferred->entry());
      __ bind(deferred->exit());
    }
  }
  
  
  void LCodeGen::DoNumberUntagD(LNumberUntagD* instr) {
    LOperand* input = instr->value();
    ASSERT(input->IsRegister());
    LOperand* temp = instr->temp();
    ASSERT(temp->IsRegister());
    LOperand* result = instr->result();
    ASSERT(result->IsDoubleRegister());
  
    Register input_reg = ToRegister(input);
    bool deoptimize_on_minus_zero =
        instr->hydrogen()->deoptimize_on_minus_zero();
    Register temp_reg = ToRegister(temp);
  
    HValue* value = instr->hydrogen()->value();
    NumberUntagDMode mode = value->representation().IsSmi()
        ? NUMBER_CANDIDATE_IS_SMI : NUMBER_CANDIDATE_IS_ANY_TAGGED;
  
    if (CpuFeatures::IsSupported(SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister result_reg = ToDoubleRegister(result);
      EmitNumberUntagD(input_reg,
                       temp_reg,
                       result_reg,
                       instr->hydrogen()->can_convert_undefined_to_nan(),
                       deoptimize_on_minus_zero,
                       instr->environment(),
                       mode);
    } else {
      EmitNumberUntagDNoSSE2(input_reg,
                             temp_reg,
                             ToX87Register(instr->result()),
                             instr->hydrogen()->can_convert_undefined_to_nan(),
                             deoptimize_on_minus_zero,
                             instr->environment(),
                             mode);
    }
  }
  
  
  void LCodeGen::DoDoubleToI(LDoubleToI* instr) {
    LOperand* input = instr->value();
    ASSERT(input->IsDoubleRegister());
    LOperand* result = instr->result();
    ASSERT(result->IsRegister());
    Register result_reg = ToRegister(result);
  
    if (instr->truncating()) {
      if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister input_reg = ToDoubleRegister(input);
        __ TruncateDoubleToI(result_reg, input_reg);
      } else {
        X87Register input_reg = ToX87Register(input);
        X87Fxch(input_reg);
        __ TruncateX87TOSToI(result_reg);
      }
    } else {
      Label bailout, done;
      if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
        CpuFeatureScope scope(masm(), SSE2);
        XMMRegister input_reg = ToDoubleRegister(input);
        XMMRegister xmm_scratch = double_scratch0();
         __ DoubleToI(result_reg, input_reg, xmm_scratch,
             instr->hydrogen()->GetMinusZeroMode(), &bailout, Label::kNear);
      } else {
        X87Register input_reg = ToX87Register(input);
        X87Fxch(input_reg);
        __ X87TOSToI(result_reg, instr->hydrogen()->GetMinusZeroMode(),
                     &bailout, Label::kNear);
      }
      __ jmp(&done, Label::kNear);
      __ bind(&bailout);
      DeoptimizeIf(no_condition, instr->environment());
      __ bind(&done);
    }
  }
  
  
  void LCodeGen::DoDoubleToSmi(LDoubleToSmi* instr) {
    LOperand* input = instr->value();
    ASSERT(input->IsDoubleRegister());
    LOperand* result = instr->result();
    ASSERT(result->IsRegister());
    Register result_reg = ToRegister(result);
  
    Label bailout, done;
    if (CpuFeatures::IsSafeForSnapshot(isolate(), SSE2)) {
      CpuFeatureScope scope(masm(), SSE2);
      XMMRegister input_reg = ToDoubleRegister(input);
      XMMRegister xmm_scratch = double_scratch0();
      __ DoubleToI(result_reg, input_reg, xmm_scratch,
          instr->hydrogen()->GetMinusZeroMode(), &bailout, Label::kNear);
    } else {
      X87Register input_reg = ToX87Register(input);
      X87Fxch(input_reg);
      __ X87TOSToI(result_reg, instr->hydrogen()->GetMinusZeroMode(),
          &bailout, Label::kNear);
    }
    __ jmp(&done, Label::kNear);
    __ bind(&bailout);
    DeoptimizeIf(no_condition, instr->environment());
    __ bind(&done);
  
    __ SmiTag(result_reg);
    DeoptimizeIf(overflow, instr->environment());
  }
  
  
  void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
    LOperand* input = instr->value();
    __ test(ToOperand(input), Immediate(kSmiTagMask));
    DeoptimizeIf(not_zero, instr->environment());
  }
  
  
  void LCodeGen::DoCheckNonSmi(LCheckNonSmi* instr) {
    if (!instr->hydrogen()->value()->IsHeapObject()) {
      LOperand* input = instr->value();
      __ test(ToOperand(input), Immediate(kSmiTagMask));
      DeoptimizeIf(zero, instr->environment());
    }
  }
  
  
  void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
    Register input = ToRegister(instr->value());
    Register temp = ToRegister(instr->temp());
  
    __ mov(temp, FieldOperand(input, HeapObject::kMapOffset));
  
    if (instr->hydrogen()->is_interval_check()) {
      InstanceType first;
      InstanceType last;
      instr->hydrogen()->GetCheckInterval(&first, &last);
  
      __ cmpb(FieldOperand(temp, Map::kInstanceTypeOffset),
              static_cast<int8_t>(first));
  
      // If there is only one type in the interval check for equality.
      if (first == last) {
        DeoptimizeIf(not_equal, instr->environment());
      } else {
        DeoptimizeIf(below, instr->environment());
        // Omit check for the last type.
        if (last != LAST_TYPE) {
          __ cmpb(FieldOperand(temp, Map::kInstanceTypeOffset),
                  static_cast<int8_t>(last));
          DeoptimizeIf(above, instr->environment());
        }
      }
    } else {
      uint8_t mask;
      uint8_t tag;
      instr->hydrogen()->GetCheckMaskAndTag(&mask, &tag);
  
      if (IsPowerOf2(mask)) {
        ASSERT(tag == 0 || IsPowerOf2(tag));
        __ test_b(FieldOperand(temp, Map::kInstanceTypeOffset), mask);
        DeoptimizeIf(tag == 0 ? not_zero : zero, instr->environment());
      } else {
        __ movzx_b(temp, FieldOperand(temp, Map::kInstanceTypeOffset));
        __ and_(temp, mask);
        __ cmp(temp, tag);
        DeoptimizeIf(not_equal, instr->environment());
      }
    }
  }
  
  
  void LCodeGen::DoCheckValue(LCheckValue* instr) {
    Handle<HeapObject> object = instr->hydrogen()->object().handle();
    if (instr->hydrogen()->object_in_new_space()) {
      Register reg = ToRegister(instr->value());
      Handle<Cell> cell = isolate()->factory()->NewCell(object);
      __ cmp(reg, Operand::ForCell(cell));
    } else {
      Operand operand = ToOperand(instr->value());
      __ cmp(operand, object);
    }
    DeoptimizeIf(not_equal, instr->environment());
  }
  
  
  void LCodeGen::DoDeferredInstanceMigration(LCheckMaps* instr, Register object) {
    {
      PushSafepointRegistersScope scope(this);
      __ push(object);
      __ xor_(esi, esi);
      __ CallRuntimeSaveDoubles(Runtime::kTryMigrateInstance);
      RecordSafepointWithRegisters(
          instr->pointer_map(), 1, Safepoint::kNoLazyDeopt);
  
      __ test(eax, Immediate(kSmiTagMask));
    }
    DeoptimizeIf(zero, instr->environment());
  }
  
  
  void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
    class DeferredCheckMaps V8_FINAL : public LDeferredCode {
     public:
      DeferredCheckMaps(LCodeGen* codegen,
                        LCheckMaps* instr,
                        Register object,
                        const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr), object_(object) {
        SetExit(check_maps());
      }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredInstanceMigration(instr_, object_);
      }
      Label* check_maps() { return &check_maps_; }
      virtual LInstruction* instr() V8_OVERRIDE { 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;
    }
  
    LOperand* input = instr->value();
    ASSERT(input->IsRegister());
    Register reg = ToRegister(input);
  
    DeferredCheckMaps* deferred = NULL;
    if (instr->hydrogen()->HasMigrationTarget()) {
      deferred = new(zone()) DeferredCheckMaps(this, instr, reg, x87_stack_);
      __ 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(reg, map);
      __ j(equal, &success, Label::kNear);
    }
  
    Handle<Map> map = maps->at(maps->size() - 1).handle();
    __ CompareMap(reg, map);
    if (instr->hydrogen()->HasMigrationTarget()) {
      __ j(not_equal, deferred->entry());
    } else {
      DeoptimizeIf(not_equal, instr->environment());
    }
  
    __ bind(&success);
  }
  
  
  void LCodeGen::DoClampDToUint8(LClampDToUint8* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister value_reg = ToDoubleRegister(instr->unclamped());
    XMMRegister xmm_scratch = double_scratch0();
    Register result_reg = ToRegister(instr->result());
    __ ClampDoubleToUint8(value_reg, xmm_scratch, result_reg);
  }
  
  
  void LCodeGen::DoClampIToUint8(LClampIToUint8* instr) {
    ASSERT(instr->unclamped()->Equals(instr->result()));
    Register value_reg = ToRegister(instr->result());
    __ ClampUint8(value_reg);
  }
  
  
  void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
    CpuFeatureScope scope(masm(), SSE2);
  
    ASSERT(instr->unclamped()->Equals(instr->result()));
    Register input_reg = ToRegister(instr->unclamped());
    XMMRegister temp_xmm_reg = ToDoubleRegister(instr->temp_xmm());
    XMMRegister xmm_scratch = double_scratch0();
    Label is_smi, done, heap_number;
  
    __ JumpIfSmi(input_reg, &is_smi);
  
    // Check for heap number
    __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
           factory()->heap_number_map());
    __ j(equal, &heap_number, Label::kNear);
  
    // Check for undefined. Undefined is converted to zero for clamping
    // conversions.
    __ cmp(input_reg, factory()->undefined_value());
    DeoptimizeIf(not_equal, instr->environment());
    __ mov(input_reg, 0);
    __ jmp(&done, Label::kNear);
  
    // Heap number
    __ bind(&heap_number);
    __ movsd(xmm_scratch, FieldOperand(input_reg, HeapNumber::kValueOffset));
    __ ClampDoubleToUint8(xmm_scratch, temp_xmm_reg, input_reg);
    __ jmp(&done, Label::kNear);
  
    // smi
    __ bind(&is_smi);
    __ SmiUntag(input_reg);
    __ ClampUint8(input_reg);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoClampTToUint8NoSSE2(LClampTToUint8NoSSE2* instr) {
    Register input_reg = ToRegister(instr->unclamped());
    Register result_reg = ToRegister(instr->result());
    Register scratch = ToRegister(instr->scratch());
    Register scratch2 = ToRegister(instr->scratch2());
    Register scratch3 = ToRegister(instr->scratch3());
    Label is_smi, done, heap_number, valid_exponent,
        largest_value, zero_result, maybe_nan_or_infinity;
  
    __ JumpIfSmi(input_reg, &is_smi);
  
    // Check for heap number
    __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
           factory()->heap_number_map());
    __ j(equal, &heap_number, Label::kNear);
  
    // Check for undefined. Undefined is converted to zero for clamping
    // conversions.
    __ cmp(input_reg, factory()->undefined_value());
    DeoptimizeIf(not_equal, instr->environment());
    __ jmp(&zero_result, Label::kNear);
  
    // Heap number
    __ bind(&heap_number);
  
    // Surprisingly, all of the hand-crafted bit-manipulations below are much
    // faster than the x86 FPU built-in instruction, especially since "banker's
    // rounding" would be additionally very expensive
  
    // Get exponent word.
    __ mov(scratch, FieldOperand(input_reg, HeapNumber::kExponentOffset));
    __ mov(scratch3, FieldOperand(input_reg, HeapNumber::kMantissaOffset));
  
    // Test for negative values --> clamp to zero
    __ test(scratch, scratch);
    __ j(negative, &zero_result, Label::kNear);
  
    // Get exponent alone in scratch2.
    __ mov(scratch2, scratch);
    __ and_(scratch2, HeapNumber::kExponentMask);
    __ shr(scratch2, HeapNumber::kExponentShift);
    __ j(zero, &zero_result, Label::kNear);
    __ sub(scratch2, Immediate(HeapNumber::kExponentBias - 1));
    __ j(negative, &zero_result, Label::kNear);
  
    const uint32_t non_int8_exponent = 7;
    __ cmp(scratch2, Immediate(non_int8_exponent + 1));
    // If the exponent is too big, check for special values.
    __ j(greater, &maybe_nan_or_infinity, Label::kNear);
  
    __ bind(&valid_exponent);
    // Exponent word in scratch, exponent in scratch2. We know that 0 <= exponent
    // < 7. The shift bias is the number of bits to shift the mantissa such that
    // with an exponent of 7 such the that top-most one is in bit 30, allowing
    // detection the rounding overflow of a 255.5 to 256 (bit 31 goes from 0 to
    // 1).
    int shift_bias = (30 - HeapNumber::kExponentShift) - 7 - 1;
    __ lea(result_reg, MemOperand(scratch2, shift_bias));
    // Here result_reg (ecx) is the shift, scratch is the exponent word.  Get the
    // top bits of the mantissa.
    __ and_(scratch, HeapNumber::kMantissaMask);
    // Put back the implicit 1 of the mantissa
    __ or_(scratch, 1 << HeapNumber::kExponentShift);
    // Shift up to round
    __ shl_cl(scratch);
    // Use "banker's rounding" to spec: If fractional part of number is 0.5, then
    // use the bit in the "ones" place and add it to the "halves" place, which has
    // the effect of rounding to even.
    __ mov(scratch2, scratch);
    const uint32_t one_half_bit_shift = 30 - sizeof(uint8_t) * 8;
    const uint32_t one_bit_shift = one_half_bit_shift + 1;
    __ and_(scratch2, Immediate((1 << one_bit_shift) - 1));
    __ cmp(scratch2, Immediate(1 << one_half_bit_shift));
    Label no_round;
    __ j(less, &no_round, Label::kNear);
    Label round_up;
    __ mov(scratch2, Immediate(1 << one_half_bit_shift));
    __ j(greater, &round_up, Label::kNear);
    __ test(scratch3, scratch3);
    __ j(not_zero, &round_up, Label::kNear);
    __ mov(scratch2, scratch);
    __ and_(scratch2, Immediate(1 << one_bit_shift));
    __ shr(scratch2, 1);
    __ bind(&round_up);
    __ add(scratch, scratch2);
    __ j(overflow, &largest_value, Label::kNear);
    __ bind(&no_round);
    __ shr(scratch, 23);
    __ mov(result_reg, scratch);
    __ jmp(&done, Label::kNear);
  
    __ bind(&maybe_nan_or_infinity);
    // Check for NaN/Infinity, all other values map to 255
    __ cmp(scratch2, Immediate(HeapNumber::kInfinityOrNanExponent + 1));
    __ j(not_equal, &largest_value, Label::kNear);
  
    // Check for NaN, which differs from Infinity in that at least one mantissa
    // bit is set.
    __ and_(scratch, HeapNumber::kMantissaMask);
    __ or_(scratch, FieldOperand(input_reg, HeapNumber::kMantissaOffset));
    __ j(not_zero, &zero_result, Label::kNear);  // M!=0 --> NaN
    // Infinity -> Fall through to map to 255.
  
    __ bind(&largest_value);
    __ mov(result_reg, Immediate(255));
    __ jmp(&done, Label::kNear);
  
    __ bind(&zero_result);
    __ xor_(result_reg, result_reg);
    __ jmp(&done, Label::kNear);
  
    // smi
    __ bind(&is_smi);
    if (!input_reg.is(result_reg)) {
      __ mov(result_reg, input_reg);
    }
    __ SmiUntag(result_reg);
    __ ClampUint8(result_reg);
    __ bind(&done);
  }
  
  
  void LCodeGen::DoDoubleBits(LDoubleBits* instr) {
    CpuFeatureScope scope(masm(), SSE2);
    XMMRegister value_reg = ToDoubleRegister(instr->value());
    Register result_reg = ToRegister(instr->result());
    if (instr->hydrogen()->bits() == HDoubleBits::HIGH) {
      if (CpuFeatures::IsSupported(SSE4_1)) {
        CpuFeatureScope scope2(masm(), SSE4_1);
        __ pextrd(result_reg, value_reg, 1);
      } else {
        XMMRegister xmm_scratch = double_scratch0();
        __ pshufd(xmm_scratch, value_reg, 1);
        __ movd(result_reg, xmm_scratch);
      }
    } else {
      __ movd(result_reg, value_reg);
    }
  }
  
  
  void LCodeGen::DoConstructDouble(LConstructDouble* instr) {
    Register hi_reg = ToRegister(instr->hi());
    Register lo_reg = ToRegister(instr->lo());
    XMMRegister result_reg = ToDoubleRegister(instr->result());
    CpuFeatureScope scope(masm(), SSE2);
  
    if (CpuFeatures::IsSupported(SSE4_1)) {
      CpuFeatureScope scope2(masm(), SSE4_1);
      __ movd(result_reg, lo_reg);
      __ pinsrd(result_reg, hi_reg, 1);
    } else {
      XMMRegister xmm_scratch = double_scratch0();
      __ movd(result_reg, hi_reg);
      __ psllq(result_reg, 32);
      __ movd(xmm_scratch, lo_reg);
      __ orps(result_reg, xmm_scratch);
    }
  }
  
  
  void LCodeGen::DoAllocate(LAllocate* instr) {
    class DeferredAllocate V8_FINAL : public LDeferredCode {
     public:
      DeferredAllocate(LCodeGen* codegen,
                       LAllocate* instr,
                       const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredAllocate(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LAllocate* instr_;
    };
  
    DeferredAllocate* deferred =
        new(zone()) DeferredAllocate(this, instr, x87_stack_);
  
    Register result = ToRegister(instr->result());
    Register temp = ToRegister(instr->temp());
  
    // Allocate memory for the object.
    AllocationFlags flags = TAG_OBJECT;
    if (instr->hydrogen()->MustAllocateDoubleAligned()) {
      flags = static_cast<AllocationFlags>(flags | DOUBLE_ALIGNMENT);
    }
    if (instr->hydrogen()->IsOldPointerSpaceAllocation()) {
      ASSERT(!instr->hydrogen()->IsOldDataSpaceAllocation());
      ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
      flags = static_cast<AllocationFlags>(flags | PRETENURE_OLD_POINTER_SPACE);
    } else if (instr->hydrogen()->IsOldDataSpaceAllocation()) {
      ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
      flags = static_cast<AllocationFlags>(flags | PRETENURE_OLD_DATA_SPACE);
    }
  
    if (instr->size()->IsConstantOperand()) {
      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
      if (size <= Page::kMaxRegularHeapObjectSize) {
        __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
      } else {
        __ jmp(deferred->entry());
      }
    } else {
      Register size = ToRegister(instr->size());
      __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
    }
  
    __ bind(deferred->exit());
  
    if (instr->hydrogen()->MustPrefillWithFiller()) {
      if (instr->size()->IsConstantOperand()) {
        int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
        __ mov(temp, (size / kPointerSize) - 1);
      } else {
        temp = ToRegister(instr->size());
        __ shr(temp, kPointerSizeLog2);
        __ dec(temp);
      }
      Label loop;
      __ bind(&loop);
      __ mov(FieldOperand(result, temp, times_pointer_size, 0),
          isolate()->factory()->one_pointer_filler_map());
      __ dec(temp);
      __ j(not_zero, &loop);
    }
  }
  
  
  void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
    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.
    __ Move(result, Immediate(Smi::FromInt(0)));
  
    PushSafepointRegistersScope scope(this);
    if (instr->size()->IsRegister()) {
      Register size = ToRegister(instr->size());
      ASSERT(!size.is(result));
      __ SmiTag(ToRegister(instr->size()));
      __ push(size);
    } else {
      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
      if (size >= 0 && size <= Smi::kMaxValue) {
        __ push(Immediate(Smi::FromInt(size)));
      } else {
        // We should never get here at runtime => abort
        __ int3();
        return;
      }
    }
  
    int flags = AllocateDoubleAlignFlag::encode(
        instr->hydrogen()->MustAllocateDoubleAligned());
    if (instr->hydrogen()->IsOldPointerSpaceAllocation()) {
      ASSERT(!instr->hydrogen()->IsOldDataSpaceAllocation());
      ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
      flags = AllocateTargetSpace::update(flags, OLD_POINTER_SPACE);
    } else if (instr->hydrogen()->IsOldDataSpaceAllocation()) {
      ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
      flags = AllocateTargetSpace::update(flags, OLD_DATA_SPACE);
    } else {
      flags = AllocateTargetSpace::update(flags, NEW_SPACE);
    }
    __ push(Immediate(Smi::FromInt(flags)));
  
    CallRuntimeFromDeferred(
        Runtime::kHiddenAllocateInTargetSpace, 2, instr, instr->context());
    __ StoreToSafepointRegisterSlot(result, eax);
  }
  
  
  void LCodeGen::DoToFastProperties(LToFastProperties* instr) {
    ASSERT(ToRegister(instr->value()).is(eax));
    __ push(eax);
    CallRuntime(Runtime::kToFastProperties, 1, instr);
  }
  
  
  void LCodeGen::DoRegExpLiteral(LRegExpLiteral* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    Label materialized;
    // Registers will be used as follows:
    // ecx = literals array.
    // ebx = regexp literal.
    // eax = regexp literal clone.
    // esi = context.
    int literal_offset =
        FixedArray::OffsetOfElementAt(instr->hydrogen()->literal_index());
    __ LoadHeapObject(ecx, instr->hydrogen()->literals());
    __ mov(ebx, FieldOperand(ecx, literal_offset));
    __ cmp(ebx, factory()->undefined_value());
    __ j(not_equal, &materialized, Label::kNear);
  
    // Create regexp literal using runtime function
    // Result will be in eax.
    __ push(ecx);
    __ push(Immediate(Smi::FromInt(instr->hydrogen()->literal_index())));
    __ push(Immediate(instr->hydrogen()->pattern()));
    __ push(Immediate(instr->hydrogen()->flags()));
    CallRuntime(Runtime::kHiddenMaterializeRegExpLiteral, 4, instr);
    __ mov(ebx, eax);
  
    __ bind(&materialized);
    int size = JSRegExp::kSize + JSRegExp::kInObjectFieldCount * kPointerSize;
    Label allocated, runtime_allocate;
    __ Allocate(size, eax, ecx, edx, &runtime_allocate, TAG_OBJECT);
    __ jmp(&allocated, Label::kNear);
  
    __ bind(&runtime_allocate);
    __ push(ebx);
    __ push(Immediate(Smi::FromInt(size)));
    CallRuntime(Runtime::kHiddenAllocateInNewSpace, 1, instr);
    __ pop(ebx);
  
    __ bind(&allocated);
    // Copy the content into the newly allocated memory.
    // (Unroll copy loop once for better throughput).
    for (int i = 0; i < size - kPointerSize; i += 2 * kPointerSize) {
      __ mov(edx, FieldOperand(ebx, i));
      __ mov(ecx, FieldOperand(ebx, i + kPointerSize));
      __ mov(FieldOperand(eax, i), edx);
      __ mov(FieldOperand(eax, i + kPointerSize), ecx);
    }
    if ((size % (2 * kPointerSize)) != 0) {
      __ mov(edx, FieldOperand(ebx, size - kPointerSize));
      __ mov(FieldOperand(eax, size - kPointerSize), edx);
    }
  }
  
  
  void LCodeGen::DoFunctionLiteral(LFunctionLiteral* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    // Use the fast case closure allocation code that allocates in new
    // space for nested functions that don't need literals cloning.
    bool pretenure = instr->hydrogen()->pretenure();
    if (!pretenure && instr->hydrogen()->has_no_literals()) {
      FastNewClosureStub stub(isolate(),
                              instr->hydrogen()->strict_mode(),
                              instr->hydrogen()->is_generator());
      __ mov(ebx, Immediate(instr->hydrogen()->shared_info()));
      CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
    } else {
      __ push(esi);
      __ push(Immediate(instr->hydrogen()->shared_info()));
      __ push(Immediate(pretenure ? factory()->true_value()
                                  : factory()->false_value()));
      CallRuntime(Runtime::kHiddenNewClosure, 3, instr);
    }
  }
  
  
  void LCodeGen::DoTypeof(LTypeof* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    LOperand* input = instr->value();
    EmitPushTaggedOperand(input);
    CallRuntime(Runtime::kTypeof, 1, instr);
  }
  
  
  void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
    Register input = ToRegister(instr->value());
    Condition final_branch_condition = EmitTypeofIs(instr, input);
    if (final_branch_condition != no_condition) {
      EmitBranch(instr, final_branch_condition);
    }
  }
  
  
  Condition LCodeGen::EmitTypeofIs(LTypeofIsAndBranch* instr, Register input) {
    Label* true_label = instr->TrueLabel(chunk_);
    Label* false_label = instr->FalseLabel(chunk_);
    Handle<String> type_name = instr->type_literal();
    int left_block = instr->TrueDestination(chunk_);
    int right_block = instr->FalseDestination(chunk_);
    int next_block = GetNextEmittedBlock();
  
    Label::Distance true_distance = left_block == next_block ? Label::kNear
                                                             : Label::kFar;
    Label::Distance false_distance = right_block == next_block ? Label::kNear
                                                               : Label::kFar;
    Condition final_branch_condition = no_condition;
    if (String::Equals(type_name, factory()->number_string())) {
      __ JumpIfSmi(input, true_label, true_distance);
      __ cmp(FieldOperand(input, HeapObject::kMapOffset),
             factory()->heap_number_map());
      final_branch_condition = equal;
  
    } else if (String::Equals(type_name, factory()->string_string())) {
      __ JumpIfSmi(input, false_label, false_distance);
      __ CmpObjectType(input, FIRST_NONSTRING_TYPE, input);
      __ j(above_equal, false_label, false_distance);
      __ test_b(FieldOperand(input, Map::kBitFieldOffset),
                1 << Map::kIsUndetectable);
      final_branch_condition = zero;
  
    } else if (String::Equals(type_name, factory()->symbol_string())) {
      __ JumpIfSmi(input, false_label, false_distance);
      __ CmpObjectType(input, SYMBOL_TYPE, input);
      final_branch_condition = equal;
  
    } else if (String::Equals(type_name, factory()->boolean_string())) {
      __ cmp(input, factory()->true_value());
      __ j(equal, true_label, true_distance);
      __ cmp(input, factory()->false_value());
      final_branch_condition = equal;
  
    } else if (FLAG_harmony_typeof &&
               String::Equals(type_name, factory()->null_string())) {
      __ cmp(input, factory()->null_value());
      final_branch_condition = equal;
  
    } else if (String::Equals(type_name, factory()->undefined_string())) {
      __ cmp(input, factory()->undefined_value());
      __ j(equal, true_label, true_distance);
      __ JumpIfSmi(input, false_label, false_distance);
      // Check for undetectable objects => true.
      __ mov(input, FieldOperand(input, HeapObject::kMapOffset));
      __ test_b(FieldOperand(input, Map::kBitFieldOffset),
                1 << Map::kIsUndetectable);
      final_branch_condition = not_zero;
  
    } else if (String::Equals(type_name, factory()->function_string())) {
      STATIC_ASSERT(NUM_OF_CALLABLE_SPEC_OBJECT_TYPES == 2);
      __ JumpIfSmi(input, false_label, false_distance);
      __ CmpObjectType(input, JS_FUNCTION_TYPE, input);
      __ j(equal, true_label, true_distance);
      __ CmpInstanceType(input, JS_FUNCTION_PROXY_TYPE);
      final_branch_condition = equal;
  
    } else if (String::Equals(type_name, factory()->object_string())) {
      __ JumpIfSmi(input, false_label, false_distance);
      if (!FLAG_harmony_typeof) {
        __ cmp(input, factory()->null_value());
        __ j(equal, true_label, true_distance);
      }
      __ CmpObjectType(input, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE, input);
      __ j(below, false_label, false_distance);
      __ CmpInstanceType(input, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
      __ j(above, false_label, false_distance);
      // Check for undetectable objects => false.
      __ test_b(FieldOperand(input, Map::kBitFieldOffset),
                1 << Map::kIsUndetectable);
      final_branch_condition = zero;
  
    } else {
      __ jmp(false_label, false_distance);
    }
    return final_branch_condition;
  }
  
  
  void LCodeGen::DoIsConstructCallAndBranch(LIsConstructCallAndBranch* instr) {
    Register temp = ToRegister(instr->temp());
  
    EmitIsConstructCall(temp);
    EmitBranch(instr, equal);
  }
  
  
  void LCodeGen::EmitIsConstructCall(Register temp) {
    // Get the frame pointer for the calling frame.
    __ mov(temp, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
  
    // Skip the arguments adaptor frame if it exists.
    Label check_frame_marker;
    __ cmp(Operand(temp, StandardFrameConstants::kContextOffset),
           Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
    __ j(not_equal, &check_frame_marker, Label::kNear);
    __ mov(temp, Operand(temp, StandardFrameConstants::kCallerFPOffset));
  
    // Check the marker in the calling frame.
    __ bind(&check_frame_marker);
    __ cmp(Operand(temp, StandardFrameConstants::kMarkerOffset),
           Immediate(Smi::FromInt(StackFrame::CONSTRUCT)));
  }
  
  
  void LCodeGen::EnsureSpaceForLazyDeopt(int space_needed) {
    if (!info()->IsStub()) {
      // Ensure that we have enough space after the previous lazy-bailout
      // instruction for patching the code here.
      int current_pc = masm()->pc_offset();
      if (current_pc < last_lazy_deopt_pc_ + space_needed) {
        int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
        __ Nop(padding_size);
      }
    }
    last_lazy_deopt_pc_ = masm()->pc_offset();
  }
  
  
  void LCodeGen::DoLazyBailout(LLazyBailout* instr) {
    last_lazy_deopt_pc_ = masm()->pc_offset();
    ASSERT(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;
    }
    Comment(";;; deoptimize: %s", instr->hydrogen()->reason());
    DeoptimizeIf(no_condition, instr->environment(), type);
  }
  
  
  void LCodeGen::DoDummy(LDummy* instr) {
    // Nothing to see here, move on!
  }
  
  
  void LCodeGen::DoDummyUse(LDummyUse* instr) {
    // Nothing to see here, move on!
  }
  
  
  void LCodeGen::DoDeferredStackCheck(LStackCheck* instr) {
    PushSafepointRegistersScope scope(this);
    __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
    __ CallRuntimeSaveDoubles(Runtime::kHiddenStackGuard);
    RecordSafepointWithLazyDeopt(
        instr, RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
    ASSERT(instr->HasEnvironment());
    LEnvironment* env = instr->environment();
    safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
  }
  
  
  void LCodeGen::DoStackCheck(LStackCheck* instr) {
    class DeferredStackCheck V8_FINAL : public LDeferredCode {
     public:
      DeferredStackCheck(LCodeGen* codegen,
                         LStackCheck* instr,
                         const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack), instr_(instr) { }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredStackCheck(instr_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LStackCheck* instr_;
    };
  
    ASSERT(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;
      ExternalReference stack_limit =
          ExternalReference::address_of_stack_limit(isolate());
      __ cmp(esp, Operand::StaticVariable(stack_limit));
      __ j(above_equal, &done, Label::kNear);
  
      ASSERT(instr->context()->IsRegister());
      ASSERT(ToRegister(instr->context()).is(esi));
      CallCode(isolate()->builtins()->StackCheck(),
               RelocInfo::CODE_TARGET,
               instr);
      __ bind(&done);
    } else {
      ASSERT(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, x87_stack_);
      ExternalReference stack_limit =
          ExternalReference::address_of_stack_limit(isolate());
      __ cmp(esp, Operand::StaticVariable(stack_limit));
      __ j(below, 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::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.
    ASSERT(!environment->HasBeenRegistered());
    RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
  
    GenerateOsrPrologue();
  }
  
  
  void LCodeGen::DoForInPrepareMap(LForInPrepareMap* instr) {
    ASSERT(ToRegister(instr->context()).is(esi));
    __ cmp(eax, isolate()->factory()->undefined_value());
    DeoptimizeIf(equal, instr->environment());
  
    __ cmp(eax, isolate()->factory()->null_value());
    DeoptimizeIf(equal, instr->environment());
  
    __ test(eax, Immediate(kSmiTagMask));
    DeoptimizeIf(zero, instr->environment());
  
    STATIC_ASSERT(FIRST_JS_PROXY_TYPE == FIRST_SPEC_OBJECT_TYPE);
    __ CmpObjectType(eax, LAST_JS_PROXY_TYPE, ecx);
    DeoptimizeIf(below_equal, instr->environment());
  
    Label use_cache, call_runtime;
    __ CheckEnumCache(&call_runtime);
  
    __ mov(eax, FieldOperand(eax, HeapObject::kMapOffset));
    __ jmp(&use_cache, Label::kNear);
  
    // Get the set of properties to enumerate.
    __ bind(&call_runtime);
    __ push(eax);
    CallRuntime(Runtime::kGetPropertyNamesFast, 1, instr);
  
    __ cmp(FieldOperand(eax, HeapObject::kMapOffset),
           isolate()->factory()->meta_map());
    DeoptimizeIf(not_equal, instr->environment());
    __ bind(&use_cache);
  }
  
  
  void LCodeGen::DoForInCacheArray(LForInCacheArray* instr) {
    Register map = ToRegister(instr->map());
    Register result = ToRegister(instr->result());
    Label load_cache, done;
    __ EnumLength(result, map);
    __ cmp(result, Immediate(Smi::FromInt(0)));
    __ j(not_equal, &load_cache, Label::kNear);
    __ mov(result, isolate()->factory()->empty_fixed_array());
    __ jmp(&done, Label::kNear);
  
    __ bind(&load_cache);
    __ LoadInstanceDescriptors(map, result);
    __ mov(result,
           FieldOperand(result, DescriptorArray::kEnumCacheOffset));
    __ mov(result,
           FieldOperand(result, FixedArray::SizeFor(instr->idx())));
    __ bind(&done);
    __ test(result, result);
    DeoptimizeIf(equal, instr->environment());
  }
  
  
  void LCodeGen::DoCheckMapValue(LCheckMapValue* instr) {
    Register object = ToRegister(instr->value());
    __ cmp(ToRegister(instr->map()),
           FieldOperand(object, HeapObject::kMapOffset));
    DeoptimizeIf(not_equal, instr->environment());
  }
  
  
  void LCodeGen::DoDeferredLoadMutableDouble(LLoadFieldByIndex* instr,
                                             Register object,
                                             Register index) {
    PushSafepointRegistersScope scope(this);
    __ push(object);
    __ push(index);
    __ xor_(esi, esi);
    __ CallRuntimeSaveDoubles(Runtime::kLoadMutableDouble);
    RecordSafepointWithRegisters(
        instr->pointer_map(), 2, Safepoint::kNoLazyDeopt);
    __ StoreToSafepointRegisterSlot(object, eax);
  }
  
  
  void LCodeGen::DoLoadFieldByIndex(LLoadFieldByIndex* instr) {
    class DeferredLoadMutableDouble V8_FINAL : public LDeferredCode {
     public:
      DeferredLoadMutableDouble(LCodeGen* codegen,
                                LLoadFieldByIndex* instr,
                                Register object,
                                Register index,
                                const X87Stack& x87_stack)
          : LDeferredCode(codegen, x87_stack),
            instr_(instr),
            object_(object),
            index_(index) {
      }
      virtual void Generate() V8_OVERRIDE {
        codegen()->DoDeferredLoadMutableDouble(instr_, object_, index_);
      }
      virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
     private:
      LLoadFieldByIndex* instr_;
      Register object_;
      Register index_;
    };
  
    Register object = ToRegister(instr->object());
    Register index = ToRegister(instr->index());
  
    DeferredLoadMutableDouble* deferred;
    deferred = new(zone()) DeferredLoadMutableDouble(
        this, instr, object, index, x87_stack_);
  
    Label out_of_object, done;
    __ test(index, Immediate(Smi::FromInt(1)));
    __ j(not_zero, deferred->entry());
  
    __ sar(index, 1);
  
    __ cmp(index, Immediate(0));
    __ j(less, &out_of_object, Label::kNear);
    __ mov(object, FieldOperand(object,
                                index,
                                times_half_pointer_size,
                                JSObject::kHeaderSize));
    __ jmp(&done, Label::kNear);
  
    __ bind(&out_of_object);
    __ mov(object, FieldOperand(object, JSObject::kPropertiesOffset));
    __ neg(index);
    // Index is now equal to out of object property index plus 1.
    __ mov(object, FieldOperand(object,
                                index,
                                times_half_pointer_size,
                                FixedArray::kHeaderSize - kPointerSize));
    __ bind(deferred->exit());
    __ bind(&done);
  }
  
  
  #undef __
  
  } }  // namespace v8::internal
  
  #endif  // V8_TARGET_ARCH_IA32
  