text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  //       notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  //       copyright notice, this list of conditions and the following
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "v8.h"
  
  #include "lithium-allocator-inl.h"
  #include "mips/lithium-mips.h"
  #include "mips/lithium-codegen-mips.h"
  #include "hydrogen-osr.h"
  
  namespace v8 {
  namespace internal {
  
  #define DEFINE_COMPILE(type)                            \
    void L##type::CompileToNative(LCodeGen* generator) {  \
      generator->Do##type(this);                          \
    }
  LITHIUM_CONCRETE_INSTRUCTION_LIST(DEFINE_COMPILE)
  #undef DEFINE_COMPILE
  
  #ifdef DEBUG
  void LInstruction::VerifyCall() {
    // Call instructions can use only fixed registers as temporaries and
    // outputs because all registers are blocked by the calling convention.
    // Inputs operands must use a fixed register or use-at-start policy or
    // a non-register policy.
    ASSERT(Output() == NULL ||
           LUnallocated::cast(Output())->HasFixedPolicy() ||
           !LUnallocated::cast(Output())->HasRegisterPolicy());
    for (UseIterator it(this); !it.Done(); it.Advance()) {
      LUnallocated* operand = LUnallocated::cast(it.Current());
      ASSERT(operand->HasFixedPolicy() ||
             operand->IsUsedAtStart());
    }
    for (TempIterator it(this); !it.Done(); it.Advance()) {
      LUnallocated* operand = LUnallocated::cast(it.Current());
      ASSERT(operand->HasFixedPolicy() ||!operand->HasRegisterPolicy());
    }
  }
  #endif
  
  
  void LInstruction::PrintTo(StringStream* stream) {
    stream->Add("%s ", this->Mnemonic());
  
    PrintOutputOperandTo(stream);
  
    PrintDataTo(stream);
  
    if (HasEnvironment()) {
      stream->Add(" ");
      environment()->PrintTo(stream);
    }
  
    if (HasPointerMap()) {
      stream->Add(" ");
      pointer_map()->PrintTo(stream);
    }
  }
  
  
  void LInstruction::PrintDataTo(StringStream* stream) {
    stream->Add("= ");
    for (int i = 0; i < InputCount(); i++) {
      if (i > 0) stream->Add(" ");
      if (InputAt(i) == NULL) {
        stream->Add("NULL");
      } else {
        InputAt(i)->PrintTo(stream);
      }
    }
  }
  
  
  void LInstruction::PrintOutputOperandTo(StringStream* stream) {
    if (HasResult()) result()->PrintTo(stream);
  }
  
  
  void LLabel::PrintDataTo(StringStream* stream) {
    LGap::PrintDataTo(stream);
    LLabel* rep = replacement();
    if (rep != NULL) {
      stream->Add(" Dead block replaced with B%d", rep->block_id());
    }
  }
  
  
  bool LGap::IsRedundant() const {
    for (int i = 0; i < 4; i++) {
      if (parallel_moves_[i] != NULL && !parallel_moves_[i]->IsRedundant()) {
        return false;
      }
    }
  
    return true;
  }
  
  
  void LGap::PrintDataTo(StringStream* stream) {
    for (int i = 0; i < 4; i++) {
      stream->Add("(");
      if (parallel_moves_[i] != NULL) {
        parallel_moves_[i]->PrintDataTo(stream);
      }
      stream->Add(") ");
    }
  }
  
  
  const char* LArithmeticD::Mnemonic() const {
    switch (op()) {
      case Token::ADD: return "add-d";
      case Token::SUB: return "sub-d";
      case Token::MUL: return "mul-d";
      case Token::DIV: return "div-d";
      case Token::MOD: return "mod-d";
      default:
        UNREACHABLE();
        return NULL;
    }
  }
  
  
  const char* LArithmeticT::Mnemonic() const {
    switch (op()) {
      case Token::ADD: return "add-t";
      case Token::SUB: return "sub-t";
      case Token::MUL: return "mul-t";
      case Token::MOD: return "mod-t";
      case Token::DIV: return "div-t";
      case Token::BIT_AND: return "bit-and-t";
      case Token::BIT_OR: return "bit-or-t";
      case Token::BIT_XOR: return "bit-xor-t";
      case Token::ROR: return "ror-t";
      case Token::SHL: return "sll-t";
      case Token::SAR: return "sra-t";
      case Token::SHR: return "srl-t";
      default:
        UNREACHABLE();
        return NULL;
    }
  }
  
  
  bool LGoto::HasInterestingComment(LCodeGen* gen) const {
    return !gen->IsNextEmittedBlock(block_id());
  }
  
  
  void LGoto::PrintDataTo(StringStream* stream) {
    stream->Add("B%d", block_id());
  }
  
  
  void LBranch::PrintDataTo(StringStream* stream) {
    stream->Add("B%d | B%d on ", true_block_id(), false_block_id());
    value()->PrintTo(stream);
  }
  
  
  LInstruction* LChunkBuilder::DoDebugBreak(HDebugBreak* instr) {
    return new(zone()) LDebugBreak();
  }
  
  
  void LCompareNumericAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if ");
    left()->PrintTo(stream);
    stream->Add(" %s ", Token::String(op()));
    right()->PrintTo(stream);
    stream->Add(" then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LIsObjectAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if is_object(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LIsStringAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if is_string(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LIsSmiAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if is_smi(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LIsUndetectableAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if is_undetectable(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LStringCompareAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if string_compare(");
    left()->PrintTo(stream);
    right()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LHasInstanceTypeAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if has_instance_type(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LHasCachedArrayIndexAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if has_cached_array_index(");
    value()->PrintTo(stream);
    stream->Add(") then B%d else B%d", true_block_id(), false_block_id());
  }
  
  
  void LClassOfTestAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if class_of_test(");
    value()->PrintTo(stream);
    stream->Add(", \"%o\") then B%d else B%d",
                *hydrogen()->class_name(),
                true_block_id(),
                false_block_id());
  }
  
  
  void LTypeofIsAndBranch::PrintDataTo(StringStream* stream) {
    stream->Add("if typeof ");
    value()->PrintTo(stream);
    stream->Add(" == \"%s\" then B%d else B%d",
                hydrogen()->type_literal()->ToCString().get(),
                true_block_id(), false_block_id());
  }
  
  
  void LStoreCodeEntry::PrintDataTo(StringStream* stream) {
    stream->Add(" = ");
    function()->PrintTo(stream);
    stream->Add(".code_entry = ");
    code_object()->PrintTo(stream);
  }
  
  
  void LInnerAllocatedObject::PrintDataTo(StringStream* stream) {
    stream->Add(" = ");
    base_object()->PrintTo(stream);
    stream->Add(" + ");
    offset()->PrintTo(stream);
  }
  
  
  void LCallJSFunction::PrintDataTo(StringStream* stream) {
    stream->Add("= ");
    function()->PrintTo(stream);
    stream->Add("#%d / ", arity());
  }
  
  
  void LCallWithDescriptor::PrintDataTo(StringStream* stream) {
    for (int i = 0; i < InputCount(); i++) {
      InputAt(i)->PrintTo(stream);
      stream->Add(" ");
    }
    stream->Add("#%d / ", arity());
  }
  
  
  void LLoadContextSlot::PrintDataTo(StringStream* stream) {
    context()->PrintTo(stream);
    stream->Add("[%d]", slot_index());
  }
  
  
  void LStoreContextSlot::PrintDataTo(StringStream* stream) {
    context()->PrintTo(stream);
    stream->Add("[%d] <- ", slot_index());
    value()->PrintTo(stream);
  }
  
  
  void LInvokeFunction::PrintDataTo(StringStream* stream) {
    stream->Add("= ");
    function()->PrintTo(stream);
    stream->Add(" #%d / ", arity());
  }
  
  
  void LCallNew::PrintDataTo(StringStream* stream) {
    stream->Add("= ");
    constructor()->PrintTo(stream);
    stream->Add(" #%d / ", arity());
  }
  
  
  void LCallNewArray::PrintDataTo(StringStream* stream) {
    stream->Add("= ");
    constructor()->PrintTo(stream);
    stream->Add(" #%d / ", arity());
    ElementsKind kind = hydrogen()->elements_kind();
    stream->Add(" (%s) ", ElementsKindToString(kind));
  }
  
  
  void LAccessArgumentsAt::PrintDataTo(StringStream* stream) {
    arguments()->PrintTo(stream);
    stream->Add(" length ");
    length()->PrintTo(stream);
    stream->Add(" index ");
    index()->PrintTo(stream);
  }
  
  
  void LStoreNamedField::PrintDataTo(StringStream* stream) {
    object()->PrintTo(stream);
    hydrogen()->access().PrintTo(stream);
    stream->Add(" <- ");
    value()->PrintTo(stream);
  }
  
  
  void LStoreNamedGeneric::PrintDataTo(StringStream* stream) {
    object()->PrintTo(stream);
    stream->Add(".");
    stream->Add(String::cast(*name())->ToCString().get());
    stream->Add(" <- ");
    value()->PrintTo(stream);
  }
  
  
  void LLoadKeyed::PrintDataTo(StringStream* stream) {
    elements()->PrintTo(stream);
    stream->Add("[");
    key()->PrintTo(stream);
    if (hydrogen()->IsDehoisted()) {
      stream->Add(" + %d]", additional_index());
    } else {
      stream->Add("]");
    }
  }
  
  
  void LStoreKeyed::PrintDataTo(StringStream* stream) {
    elements()->PrintTo(stream);
    stream->Add("[");
    key()->PrintTo(stream);
    if (hydrogen()->IsDehoisted()) {
      stream->Add(" + %d] <-", additional_index());
    } else {
      stream->Add("] <- ");
    }
  
    if (value() == NULL) {
      ASSERT(hydrogen()->IsConstantHoleStore() &&
             hydrogen()->value()->representation().IsDouble());
      stream->Add("<the hole(nan)>");
    } else {
      value()->PrintTo(stream);
    }
  }
  
  
  void LStoreKeyedGeneric::PrintDataTo(StringStream* stream) {
    object()->PrintTo(stream);
    stream->Add("[");
    key()->PrintTo(stream);
    stream->Add("] <- ");
    value()->PrintTo(stream);
  }
  
  
  void LTransitionElementsKind::PrintDataTo(StringStream* stream) {
    object()->PrintTo(stream);
    stream->Add(" %p -> %p", *original_map(), *transitioned_map());
  }
  
  
  int LPlatformChunk::GetNextSpillIndex(RegisterKind kind) {
    // Skip a slot if for a double-width slot.
    if (kind == DOUBLE_REGISTERS) spill_slot_count_++;
    return spill_slot_count_++;
  }
  
  
  LOperand* LPlatformChunk::GetNextSpillSlot(RegisterKind kind)  {
    int index = GetNextSpillIndex(kind);
    if (kind == DOUBLE_REGISTERS) {
      return LDoubleStackSlot::Create(index, zone());
    } else {
      ASSERT(kind == GENERAL_REGISTERS);
      return LStackSlot::Create(index, zone());
    }
  }
  
  
  LPlatformChunk* LChunkBuilder::Build() {
    ASSERT(is_unused());
    chunk_ = new(zone()) LPlatformChunk(info(), graph());
    LPhase phase("L_Building chunk", chunk_);
    status_ = BUILDING;
  
    // If compiling for OSR, reserve space for the unoptimized frame,
    // which will be subsumed into this frame.
    if (graph()->has_osr()) {
      for (int i = graph()->osr()->UnoptimizedFrameSlots(); i > 0; i--) {
        chunk_->GetNextSpillIndex(GENERAL_REGISTERS);
      }
    }
  
    const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
    for (int i = 0; i < blocks->length(); i++) {
      HBasicBlock* next = NULL;
      if (i < blocks->length() - 1) next = blocks->at(i + 1);
      DoBasicBlock(blocks->at(i), next);
      if (is_aborted()) return NULL;
    }
    status_ = DONE;
    return chunk_;
  }
  
  
  void LCodeGen::Abort(BailoutReason reason) {
    info()->set_bailout_reason(reason);
    status_ = ABORTED;
  }
  
  
  LUnallocated* LChunkBuilder::ToUnallocated(Register reg) {
    return new(zone()) LUnallocated(LUnallocated::FIXED_REGISTER,
                                    Register::ToAllocationIndex(reg));
  }
  
  
  LUnallocated* LChunkBuilder::ToUnallocated(DoubleRegister reg) {
    return new(zone()) LUnallocated(LUnallocated::FIXED_DOUBLE_REGISTER,
                                    DoubleRegister::ToAllocationIndex(reg));
  }
  
  
  LOperand* LChunkBuilder::UseFixed(HValue* value, Register fixed_register) {
    return Use(value, ToUnallocated(fixed_register));
  }
  
  
  LOperand* LChunkBuilder::UseFixedDouble(HValue* value, DoubleRegister reg) {
    return Use(value, ToUnallocated(reg));
  }
  
  
  LOperand* LChunkBuilder::UseRegister(HValue* value) {
    return Use(value, new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER));
  }
  
  
  LOperand* LChunkBuilder::UseRegisterAtStart(HValue* value) {
    return Use(value,
               new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER,
                                        LUnallocated::USED_AT_START));
  }
  
  
  LOperand* LChunkBuilder::UseTempRegister(HValue* value) {
    return Use(value, new(zone()) LUnallocated(LUnallocated::WRITABLE_REGISTER));
  }
  
  
  LOperand* LChunkBuilder::Use(HValue* value) {
    return Use(value, new(zone()) LUnallocated(LUnallocated::NONE));
  }
  
  
  LOperand* LChunkBuilder::UseAtStart(HValue* value) {
    return Use(value, new(zone()) LUnallocated(LUnallocated::NONE,
                                       LUnallocated::USED_AT_START));
  }
  
  
  LOperand* LChunkBuilder::UseOrConstant(HValue* value) {
    return value->IsConstant()
        ? chunk_->DefineConstantOperand(HConstant::cast(value))
        : Use(value);
  }
  
  
  LOperand* LChunkBuilder::UseOrConstantAtStart(HValue* value) {
    return value->IsConstant()
        ? chunk_->DefineConstantOperand(HConstant::cast(value))
        : UseAtStart(value);
  }
  
  
  LOperand* LChunkBuilder::UseRegisterOrConstant(HValue* value) {
    return value->IsConstant()
        ? chunk_->DefineConstantOperand(HConstant::cast(value))
        : UseRegister(value);
  }
  
  
  LOperand* LChunkBuilder::UseRegisterOrConstantAtStart(HValue* value) {
    return value->IsConstant()
        ? chunk_->DefineConstantOperand(HConstant::cast(value))
        : UseRegisterAtStart(value);
  }
  
  
  LOperand* LChunkBuilder::UseConstant(HValue* value) {
    return chunk_->DefineConstantOperand(HConstant::cast(value));
  }
  
  
  LOperand* LChunkBuilder::UseAny(HValue* value) {
    return value->IsConstant()
        ? chunk_->DefineConstantOperand(HConstant::cast(value))
        :  Use(value, new(zone()) LUnallocated(LUnallocated::ANY));
  }
  
  
  LOperand* LChunkBuilder::Use(HValue* value, LUnallocated* operand) {
    if (value->EmitAtUses()) {
      HInstruction* instr = HInstruction::cast(value);
      VisitInstruction(instr);
    }
    operand->set_virtual_register(value->id());
    return operand;
  }
  
  
  LInstruction* LChunkBuilder::Define(LTemplateResultInstruction<1>* instr,
                                      LUnallocated* result) {
    result->set_virtual_register(current_instruction_->id());
    instr->set_result(result);
    return instr;
  }
  
  
  LInstruction* LChunkBuilder::DefineAsRegister(
      LTemplateResultInstruction<1>* instr) {
    return Define(instr,
                  new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER));
  }
  
  
  LInstruction* LChunkBuilder::DefineAsSpilled(
      LTemplateResultInstruction<1>* instr, int index) {
    return Define(instr,
                  new(zone()) LUnallocated(LUnallocated::FIXED_SLOT, index));
  }
  
  
  LInstruction* LChunkBuilder::DefineSameAsFirst(
      LTemplateResultInstruction<1>* instr) {
    return Define(instr,
                  new(zone()) LUnallocated(LUnallocated::SAME_AS_FIRST_INPUT));
  }
  
  
  LInstruction* LChunkBuilder::DefineFixed(
      LTemplateResultInstruction<1>* instr, Register reg) {
    return Define(instr, ToUnallocated(reg));
  }
  
  
  LInstruction* LChunkBuilder::DefineFixedDouble(
      LTemplateResultInstruction<1>* instr, DoubleRegister reg) {
    return Define(instr, ToUnallocated(reg));
  }
  
  
  LInstruction* LChunkBuilder::AssignEnvironment(LInstruction* instr) {
    HEnvironment* hydrogen_env = current_block_->last_environment();
    int argument_index_accumulator = 0;
    ZoneList<HValue*> objects_to_materialize(0, zone());
    instr->set_environment(CreateEnvironment(hydrogen_env,
                                             &argument_index_accumulator,
                                             &objects_to_materialize));
    return instr;
  }
  
  
  LInstruction* LChunkBuilder::MarkAsCall(LInstruction* instr,
                                          HInstruction* hinstr,
                                          CanDeoptimize can_deoptimize) {
    info()->MarkAsNonDeferredCalling();
  #ifdef DEBUG
    instr->VerifyCall();
  #endif
    instr->MarkAsCall();
    instr = AssignPointerMap(instr);
  
    // If instruction does not have side-effects lazy deoptimization
    // after the call will try to deoptimize to the point before the call.
    // Thus we still need to attach environment to this call even if
    // call sequence can not deoptimize eagerly.
    bool needs_environment =
        (can_deoptimize == CAN_DEOPTIMIZE_EAGERLY) ||
        !hinstr->HasObservableSideEffects();
    if (needs_environment && !instr->HasEnvironment()) {
      instr = AssignEnvironment(instr);
    }
  
    return instr;
  }
  
  
  LInstruction* LChunkBuilder::AssignPointerMap(LInstruction* instr) {
    ASSERT(!instr->HasPointerMap());
    instr->set_pointer_map(new(zone()) LPointerMap(zone()));
    return instr;
  }
  
  
  LUnallocated* LChunkBuilder::TempRegister() {
    LUnallocated* operand =
        new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER);
    int vreg = allocator_->GetVirtualRegister();
    if (!allocator_->AllocationOk()) {
      Abort(kOutOfVirtualRegistersWhileTryingToAllocateTempRegister);
      vreg = 0;
    }
    operand->set_virtual_register(vreg);
    return operand;
  }
  
  
  LOperand* LChunkBuilder::FixedTemp(Register reg) {
    LUnallocated* operand = ToUnallocated(reg);
    ASSERT(operand->HasFixedPolicy());
    return operand;
  }
  
  
  LOperand* LChunkBuilder::FixedTemp(DoubleRegister reg) {
    LUnallocated* operand = ToUnallocated(reg);
    ASSERT(operand->HasFixedPolicy());
    return operand;
  }
  
  
  LInstruction* LChunkBuilder::DoBlockEntry(HBlockEntry* instr) {
    return new(zone()) LLabel(instr->block());
  }
  
  
  LInstruction* LChunkBuilder::DoDummyUse(HDummyUse* instr) {
    return DefineAsRegister(new(zone()) LDummyUse(UseAny(instr->value())));
  }
  
  
  LInstruction* LChunkBuilder::DoEnvironmentMarker(HEnvironmentMarker* instr) {
    UNREACHABLE();
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoDeoptimize(HDeoptimize* instr) {
    return AssignEnvironment(new(zone()) LDeoptimize);
  }
  
  
  LInstruction* LChunkBuilder::DoShift(Token::Value op,
                                       HBitwiseBinaryOperation* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      LOperand* left = UseRegisterAtStart(instr->left());
  
      HValue* right_value = instr->right();
      LOperand* right = NULL;
      int constant_value = 0;
      bool does_deopt = false;
      if (right_value->IsConstant()) {
        HConstant* constant = HConstant::cast(right_value);
        right = chunk_->DefineConstantOperand(constant);
        constant_value = constant->Integer32Value() & 0x1f;
        // Left shifts can deoptimize if we shift by > 0 and the result cannot be
        // truncated to smi.
        if (instr->representation().IsSmi() && constant_value > 0) {
          does_deopt = !instr->CheckUsesForFlag(HValue::kTruncatingToSmi);
        }
      } else {
        right = UseRegisterAtStart(right_value);
      }
  
      // Shift operations can only deoptimize if we do a logical shift
      // by 0 and the result cannot be truncated to int32.
      if (op == Token::SHR && constant_value == 0) {
        if (FLAG_opt_safe_uint32_operations) {
          does_deopt = !instr->CheckFlag(HInstruction::kUint32);
        } else {
          does_deopt = !instr->CheckUsesForFlag(HValue::kTruncatingToInt32);
        }
      }
  
      LInstruction* result =
          DefineAsRegister(new(zone()) LShiftI(op, left, right, does_deopt));
      return does_deopt ? AssignEnvironment(result) : result;
    } else {
      return DoArithmeticT(op, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoArithmeticD(Token::Value op,
                                             HArithmeticBinaryOperation* instr) {
    ASSERT(instr->representation().IsDouble());
    ASSERT(instr->left()->representation().IsDouble());
    ASSERT(instr->right()->representation().IsDouble());
    if (op == Token::MOD) {
      LOperand* left = UseFixedDouble(instr->left(), f2);
      LOperand* right = UseFixedDouble(instr->right(), f4);
      LArithmeticD* result = new(zone()) LArithmeticD(op, left, right);
      // We call a C function for double modulo. It can't trigger a GC. We need
      // to use fixed result register for the call.
      // TODO(fschneider): Allow any register as input registers.
      return MarkAsCall(DefineFixedDouble(result, f2), instr);
    } else {
      LOperand* left = UseRegisterAtStart(instr->left());
      LOperand* right = UseRegisterAtStart(instr->right());
      LArithmeticD* result = new(zone()) LArithmeticD(op, left, right);
      return DefineAsRegister(result);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoArithmeticT(Token::Value op,
                                             HBinaryOperation* instr) {
    HValue* left = instr->left();
    HValue* right = instr->right();
    ASSERT(left->representation().IsTagged());
    ASSERT(right->representation().IsTagged());
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* left_operand = UseFixed(left, a1);
    LOperand* right_operand = UseFixed(right, a0);
    LArithmeticT* result =
        new(zone()) LArithmeticT(op, context, left_operand, right_operand);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  void LChunkBuilder::DoBasicBlock(HBasicBlock* block, HBasicBlock* next_block) {
    ASSERT(is_building());
    current_block_ = block;
    next_block_ = next_block;
    if (block->IsStartBlock()) {
      block->UpdateEnvironment(graph_->start_environment());
      argument_count_ = 0;
    } else if (block->predecessors()->length() == 1) {
      // We have a single predecessor => copy environment and outgoing
      // argument count from the predecessor.
      ASSERT(block->phis()->length() == 0);
      HBasicBlock* pred = block->predecessors()->at(0);
      HEnvironment* last_environment = pred->last_environment();
      ASSERT(last_environment != NULL);
      // Only copy the environment, if it is later used again.
      if (pred->end()->SecondSuccessor() == NULL) {
        ASSERT(pred->end()->FirstSuccessor() == block);
      } else {
        if (pred->end()->FirstSuccessor()->block_id() > block->block_id() ||
            pred->end()->SecondSuccessor()->block_id() > block->block_id()) {
          last_environment = last_environment->Copy();
        }
      }
      block->UpdateEnvironment(last_environment);
      ASSERT(pred->argument_count() >= 0);
      argument_count_ = pred->argument_count();
    } else {
      // We are at a state join => process phis.
      HBasicBlock* pred = block->predecessors()->at(0);
      // No need to copy the environment, it cannot be used later.
      HEnvironment* last_environment = pred->last_environment();
      for (int i = 0; i < block->phis()->length(); ++i) {
        HPhi* phi = block->phis()->at(i);
        if (phi->HasMergedIndex()) {
          last_environment->SetValueAt(phi->merged_index(), phi);
        }
      }
      for (int i = 0; i < block->deleted_phis()->length(); ++i) {
        if (block->deleted_phis()->at(i) < last_environment->length()) {
          last_environment->SetValueAt(block->deleted_phis()->at(i),
                                       graph_->GetConstantUndefined());
        }
      }
      block->UpdateEnvironment(last_environment);
      // Pick up the outgoing argument count of one of the predecessors.
      argument_count_ = pred->argument_count();
    }
    HInstruction* current = block->first();
    int start = chunk_->instructions()->length();
    while (current != NULL && !is_aborted()) {
      // Code for constants in registers is generated lazily.
      if (!current->EmitAtUses()) {
        VisitInstruction(current);
      }
      current = current->next();
    }
    int end = chunk_->instructions()->length() - 1;
    if (end >= start) {
      block->set_first_instruction_index(start);
      block->set_last_instruction_index(end);
    }
    block->set_argument_count(argument_count_);
    next_block_ = NULL;
    current_block_ = NULL;
  }
  
  
  void LChunkBuilder::VisitInstruction(HInstruction* current) {
    HInstruction* old_current = current_instruction_;
    current_instruction_ = current;
  
    LInstruction* instr = NULL;
    if (current->CanReplaceWithDummyUses()) {
      if (current->OperandCount() == 0) {
        instr = DefineAsRegister(new(zone()) LDummy());
      } else {
        ASSERT(!current->OperandAt(0)->IsControlInstruction());
        instr = DefineAsRegister(new(zone())
            LDummyUse(UseAny(current->OperandAt(0))));
      }
      for (int i = 1; i < current->OperandCount(); ++i) {
        if (current->OperandAt(i)->IsControlInstruction()) continue;
        LInstruction* dummy =
            new(zone()) LDummyUse(UseAny(current->OperandAt(i)));
        dummy->set_hydrogen_value(current);
        chunk_->AddInstruction(dummy, current_block_);
      }
    } else {
      instr = current->CompileToLithium(this);
    }
  
    argument_count_ += current->argument_delta();
    ASSERT(argument_count_ >= 0);
  
    if (instr != NULL) {
      // Associate the hydrogen instruction first, since we may need it for
      // the ClobbersRegisters() or ClobbersDoubleRegisters() calls below.
      instr->set_hydrogen_value(current);
  
  #if DEBUG
      // Make sure that the lithium instruction has either no fixed register
      // constraints in temps or the result OR no uses that are only used at
      // start. If this invariant doesn't hold, the register allocator can decide
      // to insert a split of a range immediately before the instruction due to an
      // already allocated register needing to be used for the instruction's fixed
      // register constraint. In this case, The register allocator won't see an
      // interference between the split child and the use-at-start (it would if
      // the it was just a plain use), so it is free to move the split child into
      // the same register that is used for the use-at-start.
      // See https://code.google.com/p/chromium/issues/detail?id=201590
      if (!(instr->ClobbersRegisters() && instr->ClobbersDoubleRegisters())) {
        int fixed = 0;
        int used_at_start = 0;
        for (UseIterator it(instr); !it.Done(); it.Advance()) {
          LUnallocated* operand = LUnallocated::cast(it.Current());
          if (operand->IsUsedAtStart()) ++used_at_start;
        }
        if (instr->Output() != NULL) {
          if (LUnallocated::cast(instr->Output())->HasFixedPolicy()) ++fixed;
        }
        for (TempIterator it(instr); !it.Done(); it.Advance()) {
          LUnallocated* operand = LUnallocated::cast(it.Current());
          if (operand->HasFixedPolicy()) ++fixed;
        }
        ASSERT(fixed == 0 || used_at_start == 0);
      }
  #endif
  
      if (FLAG_stress_pointer_maps && !instr->HasPointerMap()) {
        instr = AssignPointerMap(instr);
      }
      if (FLAG_stress_environments && !instr->HasEnvironment()) {
        instr = AssignEnvironment(instr);
      }
      chunk_->AddInstruction(instr, current_block_);
  
      if (instr->IsCall()) {
        HValue* hydrogen_value_for_lazy_bailout = current;
        LInstruction* instruction_needing_environment = NULL;
        if (current->HasObservableSideEffects()) {
          HSimulate* sim = HSimulate::cast(current->next());
          instruction_needing_environment = instr;
          sim->ReplayEnvironment(current_block_->last_environment());
          hydrogen_value_for_lazy_bailout = sim;
        }
        LInstruction* bailout = AssignEnvironment(new(zone()) LLazyBailout());
        bailout->set_hydrogen_value(hydrogen_value_for_lazy_bailout);
        chunk_->AddInstruction(bailout, current_block_);
        if (instruction_needing_environment != NULL) {
          // Store the lazy deopt environment with the instruction if needed.
          // Right now it is only used for LInstanceOfKnownGlobal.
          instruction_needing_environment->
              SetDeferredLazyDeoptimizationEnvironment(bailout->environment());
        }
      }
    }
    current_instruction_ = old_current;
  }
  
  
  LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
    return new(zone()) LGoto(instr->FirstSuccessor());
  }
  
  
  LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
    LInstruction* goto_instr = CheckElideControlInstruction(instr);
    if (goto_instr != NULL) return goto_instr;
  
    HValue* value = instr->value();
    LBranch* result = new(zone()) LBranch(UseRegister(value));
    // Tagged values that are not known smis or booleans require a
    // deoptimization environment. If the instruction is generic no
    // environment is needed since all cases are handled.
    Representation rep = value->representation();
    HType type = value->type();
    ToBooleanStub::Types expected = instr->expected_input_types();
    if (rep.IsTagged() && !type.IsSmi() && !type.IsBoolean() &&
        !expected.IsGeneric()) {
      return AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoCompareMap(HCompareMap* instr) {
    LInstruction* goto_instr = CheckElideControlInstruction(instr);
    if (goto_instr != NULL) return goto_instr;
  
    ASSERT(instr->value()->representation().IsTagged());
    LOperand* value = UseRegisterAtStart(instr->value());
    LOperand* temp = TempRegister();
    return new(zone()) LCmpMapAndBranch(value, temp);
  }
  
  
  LInstruction* LChunkBuilder::DoArgumentsLength(HArgumentsLength* length) {
    info()->MarkAsRequiresFrame();
    return DefineAsRegister(
        new(zone()) LArgumentsLength(UseRegister(length->value())));
  }
  
  
  LInstruction* LChunkBuilder::DoArgumentsElements(HArgumentsElements* elems) {
    info()->MarkAsRequiresFrame();
    return DefineAsRegister(new(zone()) LArgumentsElements);
  }
  
  
  LInstruction* LChunkBuilder::DoInstanceOf(HInstanceOf* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LInstanceOf* result =
        new(zone()) LInstanceOf(context, UseFixed(instr->left(), a0),
                                UseFixed(instr->right(), a1));
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoInstanceOfKnownGlobal(
      HInstanceOfKnownGlobal* instr) {
    LInstanceOfKnownGlobal* result =
        new(zone()) LInstanceOfKnownGlobal(
            UseFixed(instr->context(), cp),
            UseFixed(instr->left(), a0),
            FixedTemp(t0));
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoWrapReceiver(HWrapReceiver* instr) {
    LOperand* receiver = UseRegisterAtStart(instr->receiver());
    LOperand* function = UseRegisterAtStart(instr->function());
    LWrapReceiver* result = new(zone()) LWrapReceiver(receiver, function);
    return AssignEnvironment(DefineAsRegister(result));
  }
  
  
  LInstruction* LChunkBuilder::DoApplyArguments(HApplyArguments* instr) {
    LOperand* function = UseFixed(instr->function(), a1);
    LOperand* receiver = UseFixed(instr->receiver(), a0);
    LOperand* length = UseFixed(instr->length(), a2);
    LOperand* elements = UseFixed(instr->elements(), a3);
    LApplyArguments* result = new(zone()) LApplyArguments(function,
                                                          receiver,
                                                          length,
                                                          elements);
    return MarkAsCall(DefineFixed(result, v0), instr, CAN_DEOPTIMIZE_EAGERLY);
  }
  
  
  LInstruction* LChunkBuilder::DoPushArgument(HPushArgument* instr) {
    LOperand* argument = Use(instr->argument());
    return new(zone()) LPushArgument(argument);
  }
  
  
  LInstruction* LChunkBuilder::DoStoreCodeEntry(
      HStoreCodeEntry* store_code_entry) {
    LOperand* function = UseRegister(store_code_entry->function());
    LOperand* code_object = UseTempRegister(store_code_entry->code_object());
    return new(zone()) LStoreCodeEntry(function, code_object);
  }
  
  
  LInstruction* LChunkBuilder::DoInnerAllocatedObject(
      HInnerAllocatedObject* instr) {
    LOperand* base_object = UseRegisterAtStart(instr->base_object());
    LOperand* offset = UseRegisterOrConstantAtStart(instr->offset());
    return DefineAsRegister(
        new(zone()) LInnerAllocatedObject(base_object, offset));
  }
  
  
  LInstruction* LChunkBuilder::DoThisFunction(HThisFunction* instr) {
    return instr->HasNoUses()
        ? NULL
        : DefineAsRegister(new(zone()) LThisFunction);
  }
  
  
  LInstruction* LChunkBuilder::DoContext(HContext* instr) {
    if (instr->HasNoUses()) return NULL;
  
    if (info()->IsStub()) {
      return DefineFixed(new(zone()) LContext, cp);
    }
  
    return DefineAsRegister(new(zone()) LContext);
  }
  
  
  LInstruction* LChunkBuilder::DoDeclareGlobals(HDeclareGlobals* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    return MarkAsCall(new(zone()) LDeclareGlobals(context), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCallJSFunction(
      HCallJSFunction* instr) {
    LOperand* function = UseFixed(instr->function(), a1);
  
    LCallJSFunction* result = new(zone()) LCallJSFunction(function);
  
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCallWithDescriptor(
      HCallWithDescriptor* instr) {
    const CallInterfaceDescriptor* descriptor = instr->descriptor();
  
    LOperand* target = UseRegisterOrConstantAtStart(instr->target());
    ZoneList<LOperand*> ops(instr->OperandCount(), zone());
    ops.Add(target, zone());
    for (int i = 1; i < instr->OperandCount(); i++) {
      LOperand* op = UseFixed(instr->OperandAt(i),
          descriptor->GetParameterRegister(i - 1));
      ops.Add(op, zone());
    }
  
    LCallWithDescriptor* result = new(zone()) LCallWithDescriptor(
        descriptor, ops, zone());
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoInvokeFunction(HInvokeFunction* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* function = UseFixed(instr->function(), a1);
    LInvokeFunction* result = new(zone()) LInvokeFunction(context, function);
    return MarkAsCall(DefineFixed(result, v0), instr, CANNOT_DEOPTIMIZE_EAGERLY);
  }
  
  
  LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
    switch (instr->op()) {
      case kMathFloor: return DoMathFloor(instr);
      case kMathRound: return DoMathRound(instr);
      case kMathAbs: return DoMathAbs(instr);
      case kMathLog: return DoMathLog(instr);
      case kMathExp: return DoMathExp(instr);
      case kMathSqrt: return DoMathSqrt(instr);
      case kMathPowHalf: return DoMathPowHalf(instr);
      case kMathClz32: return DoMathClz32(instr);
      default:
        UNREACHABLE();
        return NULL;
    }
  }
  
  
  LInstruction* LChunkBuilder::DoMathLog(HUnaryMathOperation* instr) {
    ASSERT(instr->representation().IsDouble());
    ASSERT(instr->value()->representation().IsDouble());
    LOperand* input = UseFixedDouble(instr->value(), f4);
    return MarkAsCall(DefineFixedDouble(new(zone()) LMathLog(input), f4), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoMathClz32(HUnaryMathOperation* instr) {
    LOperand* input = UseRegisterAtStart(instr->value());
    LMathClz32* result = new(zone()) LMathClz32(input);
    return DefineAsRegister(result);
  }
  
  
  LInstruction* LChunkBuilder::DoMathExp(HUnaryMathOperation* instr) {
    ASSERT(instr->representation().IsDouble());
    ASSERT(instr->value()->representation().IsDouble());
    LOperand* input = UseRegister(instr->value());
    LOperand* temp1 = TempRegister();
    LOperand* temp2 = TempRegister();
    LOperand* double_temp = FixedTemp(f6);  // Chosen by fair dice roll.
    LMathExp* result = new(zone()) LMathExp(input, double_temp, temp1, temp2);
    return DefineAsRegister(result);
  }
  
  
  LInstruction* LChunkBuilder::DoMathPowHalf(HUnaryMathOperation* instr) {
    // Input cannot be the same as the result, see LCodeGen::DoMathPowHalf.
    LOperand* input = UseFixedDouble(instr->value(), f8);
    LOperand* temp = FixedTemp(f6);
    LMathPowHalf* result = new(zone()) LMathPowHalf(input, temp);
    return DefineFixedDouble(result, f4);
  }
  
  
  LInstruction* LChunkBuilder::DoMathAbs(HUnaryMathOperation* instr) {
    Representation r = instr->value()->representation();
    LOperand* context = (r.IsDouble() || r.IsSmiOrInteger32())
        ? NULL
        : UseFixed(instr->context(), cp);
    LOperand* input = UseRegister(instr->value());
    LMathAbs* result = new(zone()) LMathAbs(context, input);
    return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
  }
  
  
  LInstruction* LChunkBuilder::DoMathFloor(HUnaryMathOperation* instr) {
    LOperand* input = UseRegister(instr->value());
    LOperand* temp = TempRegister();
    LMathFloor* result = new(zone()) LMathFloor(input, temp);
    return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
  }
  
  
  LInstruction* LChunkBuilder::DoMathSqrt(HUnaryMathOperation* instr) {
    LOperand* input = UseRegister(instr->value());
    LMathSqrt* result = new(zone()) LMathSqrt(input);
    return DefineAsRegister(result);
  }
  
  
  LInstruction* LChunkBuilder::DoMathRound(HUnaryMathOperation* instr) {
    LOperand* input = UseRegister(instr->value());
    LOperand* temp = FixedTemp(f6);
    LMathRound* result = new(zone()) LMathRound(input, temp);
    return AssignEnvironment(DefineAsRegister(result));
  }
  
  
  LInstruction* LChunkBuilder::DoCallNew(HCallNew* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* constructor = UseFixed(instr->constructor(), a1);
    LCallNew* result = new(zone()) LCallNew(context, constructor);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCallNewArray(HCallNewArray* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* constructor = UseFixed(instr->constructor(), a1);
    LCallNewArray* result = new(zone()) LCallNewArray(context, constructor);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCallFunction(HCallFunction* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* function = UseFixed(instr->function(), a1);
    LCallFunction* call = new(zone()) LCallFunction(context, function);
    return MarkAsCall(DefineFixed(call, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCallRuntime(HCallRuntime* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    return MarkAsCall(DefineFixed(new(zone()) LCallRuntime(context), v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoRor(HRor* instr) {
    return DoShift(Token::ROR, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoShr(HShr* instr) {
    return DoShift(Token::SHR, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoSar(HSar* instr) {
    return DoShift(Token::SAR, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoShl(HShl* instr) {
    return DoShift(Token::SHL, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoBitwise(HBitwise* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      ASSERT(instr->CheckFlag(HValue::kTruncatingToInt32));
  
      LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
      LOperand* right = UseOrConstantAtStart(instr->BetterRightOperand());
      return DefineAsRegister(new(zone()) LBitI(left, right));
    } else {
      return DoArithmeticT(instr->op(), instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoDivByPowerOf2I(HDiv* instr) {
    ASSERT(instr->representation().IsSmiOrInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result = DefineAsRegister(new(zone()) LDivByPowerOf2I(
            dividend, divisor));
    if ((instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) ||
        (instr->CheckFlag(HValue::kCanOverflow) && divisor == -1) ||
        (!instr->CheckFlag(HInstruction::kAllUsesTruncatingToInt32) &&
         divisor != 1 && divisor != -1)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoDivByConstI(HDiv* instr) {
    ASSERT(instr->representation().IsInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result = DefineAsRegister(new(zone()) LDivByConstI(
            dividend, divisor));
    if (divisor == 0 ||
        (instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) ||
        !instr->CheckFlag(HInstruction::kAllUsesTruncatingToInt32)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoDivI(HBinaryOperation* instr) {
    ASSERT(instr->representation().IsSmiOrInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    LOperand* divisor = UseRegister(instr->right());
    LDivI* div = new(zone()) LDivI(dividend, divisor);
    return AssignEnvironment(DefineAsRegister(div));
  }
  
  
  LInstruction* LChunkBuilder::DoDiv(HDiv* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      if (instr->RightIsPowerOf2()) {
        return DoDivByPowerOf2I(instr);
      } else if (instr->right()->IsConstant()) {
        return DoDivByConstI(instr);
      } else {
        return DoDivI(instr);
      }
    } else if (instr->representation().IsDouble()) {
      return DoArithmeticD(Token::DIV, instr);
    } else {
      return DoArithmeticT(Token::DIV, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoFlooringDivByPowerOf2I(HMathFloorOfDiv* instr) {
    LOperand* dividend = UseRegisterAtStart(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result = DefineAsRegister(new(zone()) LFlooringDivByPowerOf2I(
            dividend, divisor));
    if ((instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0) ||
        (instr->CheckFlag(HValue::kLeftCanBeMinInt) && divisor == -1)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoFlooringDivByConstI(HMathFloorOfDiv* instr) {
    ASSERT(instr->representation().IsInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result =
        DefineAsRegister(new(zone()) LFlooringDivByConstI(dividend, divisor));
    bool can_deopt =
        divisor == 0 ||
        (instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0);
    return can_deopt ? AssignEnvironment(result) : result;
  }
  
  
  LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) {
    if (instr->RightIsPowerOf2()) {
      return DoFlooringDivByPowerOf2I(instr);
    } else if (false && instr->right()->IsConstant()) {
      return DoFlooringDivByConstI(instr);  // TODO(svenpanne) Fix and re-enable.
    } else {
      return DoDivI(instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoModByPowerOf2I(HMod* instr) {
    ASSERT(instr->representation().IsSmiOrInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegisterAtStart(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result = DefineSameAsFirst(new(zone()) LModByPowerOf2I(
            dividend, divisor));
    if (instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoModByConstI(HMod* instr) {
    ASSERT(instr->representation().IsSmiOrInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    int32_t divisor = instr->right()->GetInteger32Constant();
    LInstruction* result = DefineAsRegister(new(zone()) LModByConstI(
            dividend, divisor));
    if (divisor == 0 || instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoModI(HMod* instr) {
    ASSERT(instr->representation().IsSmiOrInteger32());
    ASSERT(instr->left()->representation().Equals(instr->representation()));
    ASSERT(instr->right()->representation().Equals(instr->representation()));
    LOperand* dividend = UseRegister(instr->left());
    LOperand* divisor = UseRegister(instr->right());
    LInstruction* result = DefineAsRegister(new(zone()) LModI(
        dividend, divisor));
    if (instr->CheckFlag(HValue::kCanBeDivByZero) ||
        instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
      result = AssignEnvironment(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoMod(HMod* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      return instr->RightIsPowerOf2() ? DoModByPowerOf2I(instr) : DoModI(instr);
    } else if (instr->representation().IsDouble()) {
      return DoArithmeticD(Token::MOD, instr);
    } else {
      return DoArithmeticT(Token::MOD, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoMul(HMul* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      HValue* left = instr->BetterLeftOperand();
      HValue* right = instr->BetterRightOperand();
      LOperand* left_op;
      LOperand* right_op;
      bool can_overflow = instr->CheckFlag(HValue::kCanOverflow);
      bool bailout_on_minus_zero = instr->CheckFlag(HValue::kBailoutOnMinusZero);
  
      if (right->IsConstant()) {
        HConstant* constant = HConstant::cast(right);
        int32_t constant_value = constant->Integer32Value();
        // Constants -1, 0 and 1 can be optimized if the result can overflow.
        // For other constants, it can be optimized only without overflow.
        if (!can_overflow || ((constant_value >= -1) && (constant_value <= 1))) {
          left_op = UseRegisterAtStart(left);
          right_op = UseConstant(right);
        } else {
          if (bailout_on_minus_zero) {
            left_op = UseRegister(left);
          } else {
            left_op = UseRegisterAtStart(left);
          }
          right_op = UseRegister(right);
        }
      } else {
        if (bailout_on_minus_zero) {
          left_op = UseRegister(left);
        } else {
          left_op = UseRegisterAtStart(left);
        }
        right_op = UseRegister(right);
      }
      LMulI* mul = new(zone()) LMulI(left_op, right_op);
      if (can_overflow || bailout_on_minus_zero) {
        AssignEnvironment(mul);
      }
      return DefineAsRegister(mul);
  
    } else if (instr->representation().IsDouble()) {
      if (kArchVariant == kMips32r2) {
        if (instr->UseCount() == 1 && instr->uses().value()->IsAdd()) {
          HAdd* add = HAdd::cast(instr->uses().value());
          if (instr == add->left()) {
            // This mul is the lhs of an add. The add and mul will be folded
            // into a multiply-add.
            return NULL;
          }
          if (instr == add->right() && !add->left()->IsMul()) {
            // This mul is the rhs of an add, where the lhs is not another mul.
            // The add and mul will be folded into a multiply-add.
            return NULL;
          }
        }
      }
      return DoArithmeticD(Token::MUL, instr);
    } else {
      return DoArithmeticT(Token::MUL, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoSub(HSub* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      LOperand* left = UseRegisterAtStart(instr->left());
      LOperand* right = UseOrConstantAtStart(instr->right());
      LSubI* sub = new(zone()) LSubI(left, right);
      LInstruction* result = DefineAsRegister(sub);
      if (instr->CheckFlag(HValue::kCanOverflow)) {
        result = AssignEnvironment(result);
      }
      return result;
    } else if (instr->representation().IsDouble()) {
      return DoArithmeticD(Token::SUB, instr);
    } else {
      return DoArithmeticT(Token::SUB, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoMultiplyAdd(HMul* mul, HValue* addend) {
    LOperand* multiplier_op = UseRegisterAtStart(mul->left());
    LOperand* multiplicand_op = UseRegisterAtStart(mul->right());
    LOperand* addend_op = UseRegisterAtStart(addend);
    return DefineSameAsFirst(new(zone()) LMultiplyAddD(addend_op, multiplier_op,
                                                       multiplicand_op));
  }
  
  
  LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
      LOperand* right = UseOrConstantAtStart(instr->BetterRightOperand());
      LAddI* add = new(zone()) LAddI(left, right);
      LInstruction* result = DefineAsRegister(add);
      if (instr->CheckFlag(HValue::kCanOverflow)) {
        result = AssignEnvironment(result);
      }
      return result;
    } else if (instr->representation().IsExternal()) {
      ASSERT(instr->left()->representation().IsExternal());
      ASSERT(instr->right()->representation().IsInteger32());
      ASSERT(!instr->CheckFlag(HValue::kCanOverflow));
      LOperand* left = UseRegisterAtStart(instr->left());
      LOperand* right = UseOrConstantAtStart(instr->right());
      LAddI* add = new(zone()) LAddI(left, right);
      LInstruction* result = DefineAsRegister(add);
      return result;
    } else if (instr->representation().IsDouble()) {
      if (kArchVariant == kMips32r2) {
        if (instr->left()->IsMul())
          return DoMultiplyAdd(HMul::cast(instr->left()), instr->right());
  
        if (instr->right()->IsMul()) {
          ASSERT(!instr->left()->IsMul());
          return DoMultiplyAdd(HMul::cast(instr->right()), instr->left());
        }
      }
      return DoArithmeticD(Token::ADD, instr);
    } else {
      return DoArithmeticT(Token::ADD, instr);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
    LOperand* left = NULL;
    LOperand* right = NULL;
    if (instr->representation().IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(instr->representation()));
      ASSERT(instr->right()->representation().Equals(instr->representation()));
      left = UseRegisterAtStart(instr->BetterLeftOperand());
      right = UseOrConstantAtStart(instr->BetterRightOperand());
    } else {
      ASSERT(instr->representation().IsDouble());
      ASSERT(instr->left()->representation().IsDouble());
      ASSERT(instr->right()->representation().IsDouble());
      left = UseRegisterAtStart(instr->left());
      right = UseRegisterAtStart(instr->right());
    }
    return DefineAsRegister(new(zone()) LMathMinMax(left, right));
  }
  
  
  LInstruction* LChunkBuilder::DoPower(HPower* instr) {
    ASSERT(instr->representation().IsDouble());
    // We call a C function for double power. It can't trigger a GC.
    // We need to use fixed result register for the call.
    Representation exponent_type = instr->right()->representation();
    ASSERT(instr->left()->representation().IsDouble());
    LOperand* left = UseFixedDouble(instr->left(), f2);
    LOperand* right = exponent_type.IsDouble() ?
        UseFixedDouble(instr->right(), f4) :
        UseFixed(instr->right(), a2);
    LPower* result = new(zone()) LPower(left, right);
    return MarkAsCall(DefineFixedDouble(result, f0),
                      instr,
                      CAN_DEOPTIMIZE_EAGERLY);
  }
  
  
  LInstruction* LChunkBuilder::DoCompareGeneric(HCompareGeneric* instr) {
    ASSERT(instr->left()->representation().IsTagged());
    ASSERT(instr->right()->representation().IsTagged());
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* left = UseFixed(instr->left(), a1);
    LOperand* right = UseFixed(instr->right(), a0);
    LCmpT* result = new(zone()) LCmpT(context, left, right);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoCompareNumericAndBranch(
      HCompareNumericAndBranch* instr) {
    Representation r = instr->representation();
    if (r.IsSmiOrInteger32()) {
      ASSERT(instr->left()->representation().Equals(r));
      ASSERT(instr->right()->representation().Equals(r));
      LOperand* left = UseRegisterOrConstantAtStart(instr->left());
      LOperand* right = UseRegisterOrConstantAtStart(instr->right());
      return new(zone()) LCompareNumericAndBranch(left, right);
    } else {
      ASSERT(r.IsDouble());
      ASSERT(instr->left()->representation().IsDouble());
      ASSERT(instr->right()->representation().IsDouble());
      LOperand* left = UseRegisterAtStart(instr->left());
      LOperand* right = UseRegisterAtStart(instr->right());
      return new(zone()) LCompareNumericAndBranch(left, right);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoCompareObjectEqAndBranch(
      HCompareObjectEqAndBranch* instr) {
    LInstruction* goto_instr = CheckElideControlInstruction(instr);
    if (goto_instr != NULL) return goto_instr;
    LOperand* left = UseRegisterAtStart(instr->left());
    LOperand* right = UseRegisterAtStart(instr->right());
    return new(zone()) LCmpObjectEqAndBranch(left, right);
  }
  
  
  LInstruction* LChunkBuilder::DoCompareHoleAndBranch(
      HCompareHoleAndBranch* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    return new(zone()) LCmpHoleAndBranch(value);
  }
  
  
  LInstruction* LChunkBuilder::DoCompareMinusZeroAndBranch(
      HCompareMinusZeroAndBranch* instr) {
    LInstruction* goto_instr = CheckElideControlInstruction(instr);
    if (goto_instr != NULL) return goto_instr;
    LOperand* value = UseRegister(instr->value());
    LOperand* scratch = TempRegister();
    return new(zone()) LCompareMinusZeroAndBranch(value, scratch);
  }
  
  
  LInstruction* LChunkBuilder::DoIsObjectAndBranch(HIsObjectAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    LOperand* temp = TempRegister();
    return new(zone()) LIsObjectAndBranch(UseRegisterAtStart(instr->value()),
                                          temp);
  }
  
  
  LInstruction* LChunkBuilder::DoIsStringAndBranch(HIsStringAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    LOperand* temp = TempRegister();
    return new(zone()) LIsStringAndBranch(UseRegisterAtStart(instr->value()),
                                          temp);
  }
  
  
  LInstruction* LChunkBuilder::DoIsSmiAndBranch(HIsSmiAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    return new(zone()) LIsSmiAndBranch(Use(instr->value()));
  }
  
  
  LInstruction* LChunkBuilder::DoIsUndetectableAndBranch(
      HIsUndetectableAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    return new(zone()) LIsUndetectableAndBranch(
        UseRegisterAtStart(instr->value()), TempRegister());
  }
  
  
  LInstruction* LChunkBuilder::DoStringCompareAndBranch(
      HStringCompareAndBranch* instr) {
    ASSERT(instr->left()->representation().IsTagged());
    ASSERT(instr->right()->representation().IsTagged());
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* left = UseFixed(instr->left(), a1);
    LOperand* right = UseFixed(instr->right(), a0);
    LStringCompareAndBranch* result =
        new(zone()) LStringCompareAndBranch(context, left, right);
    return MarkAsCall(result, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoHasInstanceTypeAndBranch(
      HHasInstanceTypeAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    LOperand* value = UseRegisterAtStart(instr->value());
    return new(zone()) LHasInstanceTypeAndBranch(value);
  }
  
  
  LInstruction* LChunkBuilder::DoGetCachedArrayIndex(
      HGetCachedArrayIndex* instr)  {
    ASSERT(instr->value()->representation().IsTagged());
    LOperand* value = UseRegisterAtStart(instr->value());
  
    return DefineAsRegister(new(zone()) LGetCachedArrayIndex(value));
  }
  
  
  LInstruction* LChunkBuilder::DoHasCachedArrayIndexAndBranch(
      HHasCachedArrayIndexAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    return new(zone()) LHasCachedArrayIndexAndBranch(
        UseRegisterAtStart(instr->value()));
  }
  
  
  LInstruction* LChunkBuilder::DoClassOfTestAndBranch(
      HClassOfTestAndBranch* instr) {
    ASSERT(instr->value()->representation().IsTagged());
    return new(zone()) LClassOfTestAndBranch(UseRegister(instr->value()),
                                             TempRegister());
  }
  
  
  LInstruction* LChunkBuilder::DoMapEnumLength(HMapEnumLength* instr) {
    LOperand* map = UseRegisterAtStart(instr->value());
    return DefineAsRegister(new(zone()) LMapEnumLength(map));
  }
  
  
  LInstruction* LChunkBuilder::DoDateField(HDateField* instr) {
    LOperand* object = UseFixed(instr->value(), a0);
    LDateField* result =
        new(zone()) LDateField(object, FixedTemp(a1), instr->index());
    return MarkAsCall(DefineFixed(result, v0), instr, CAN_DEOPTIMIZE_EAGERLY);
  }
  
  
  LInstruction* LChunkBuilder::DoSeqStringGetChar(HSeqStringGetChar* instr) {
    LOperand* string = UseRegisterAtStart(instr->string());
    LOperand* index = UseRegisterOrConstantAtStart(instr->index());
    return DefineAsRegister(new(zone()) LSeqStringGetChar(string, index));
  }
  
  
  LInstruction* LChunkBuilder::DoSeqStringSetChar(HSeqStringSetChar* instr) {
    LOperand* string = UseRegisterAtStart(instr->string());
    LOperand* index = FLAG_debug_code
        ? UseRegisterAtStart(instr->index())
        : UseRegisterOrConstantAtStart(instr->index());
    LOperand* value = UseRegisterAtStart(instr->value());
    LOperand* context = FLAG_debug_code ? UseFixed(instr->context(), cp) : NULL;
    return new(zone()) LSeqStringSetChar(context, string, index, value);
  }
  
  
  LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
    LOperand* value = UseRegisterOrConstantAtStart(instr->index());
    LOperand* length = UseRegister(instr->length());
    return AssignEnvironment(new(zone()) LBoundsCheck(value, length));
  }
  
  
  LInstruction* LChunkBuilder::DoBoundsCheckBaseIndexInformation(
      HBoundsCheckBaseIndexInformation* instr) {
    UNREACHABLE();
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoAbnormalExit(HAbnormalExit* instr) {
    // The control instruction marking the end of a block that completed
    // abruptly (e.g., threw an exception).  There is nothing specific to do.
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoUseConst(HUseConst* instr) {
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoForceRepresentation(HForceRepresentation* bad) {
    // All HForceRepresentation instructions should be eliminated in the
    // representation change phase of Hydrogen.
    UNREACHABLE();
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoChange(HChange* instr) {
    Representation from = instr->from();
    Representation to = instr->to();
    if (from.IsSmi()) {
      if (to.IsTagged()) {
        LOperand* value = UseRegister(instr->value());
        return DefineSameAsFirst(new(zone()) LDummyUse(value));
      }
      from = Representation::Tagged();
    }
    if (from.IsTagged()) {
      if (to.IsDouble()) {
        LOperand* value = UseRegister(instr->value());
        LNumberUntagD* res = new(zone()) LNumberUntagD(value);
        return AssignEnvironment(DefineAsRegister(res));
      } else if (to.IsSmi()) {
        HValue* val = instr->value();
        LOperand* value = UseRegister(val);
        if (val->type().IsSmi()) {
          return DefineSameAsFirst(new(zone()) LDummyUse(value));
        }
        return AssignEnvironment(DefineSameAsFirst(new(zone()) LCheckSmi(value)));
      } else {
        ASSERT(to.IsInteger32());
        LOperand* value = NULL;
        LInstruction* res = NULL;
        HValue* val = instr->value();
        if (val->type().IsSmi() || val->representation().IsSmi()) {
          value = UseRegisterAtStart(val);
          res = DefineAsRegister(new(zone()) LSmiUntag(value, false));
        } else {
          value = UseRegister(val);
          LOperand* temp1 = TempRegister();
          LOperand* temp2 = FixedTemp(f22);
          res = DefineSameAsFirst(new(zone()) LTaggedToI(value,
                                                         temp1,
                                                         temp2));
          res = AssignEnvironment(res);
        }
        return res;
      }
    } else if (from.IsDouble()) {
      if (to.IsTagged()) {
        info()->MarkAsDeferredCalling();
        LOperand* value = UseRegister(instr->value());
        LOperand* temp1 = TempRegister();
        LOperand* temp2 = TempRegister();
  
        // Make sure that the temp and result_temp registers are
        // different.
        LUnallocated* result_temp = TempRegister();
        LNumberTagD* result = new(zone()) LNumberTagD(value, temp1, temp2);
        Define(result, result_temp);
        return AssignPointerMap(result);
      } else if (to.IsSmi()) {
        LOperand* value = UseRegister(instr->value());
        return AssignEnvironment(
            DefineAsRegister(new(zone()) LDoubleToSmi(value)));
      } else {
        ASSERT(to.IsInteger32());
        LOperand* value = UseRegister(instr->value());
        LDoubleToI* res = new(zone()) LDoubleToI(value);
        return AssignEnvironment(DefineAsRegister(res));
      }
    } else if (from.IsInteger32()) {
      info()->MarkAsDeferredCalling();
      if (to.IsTagged()) {
        HValue* val = instr->value();
        LOperand* value = UseRegisterAtStart(val);
        if (!instr->CheckFlag(HValue::kCanOverflow)) {
          return DefineAsRegister(new(zone()) LSmiTag(value));
        } else if (val->CheckFlag(HInstruction::kUint32)) {
          LOperand* temp1 = TempRegister();
          LOperand* temp2 = TempRegister();
          LNumberTagU* result = new(zone()) LNumberTagU(value, temp1, temp2);
          return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
        } else {
          LOperand* temp1 = TempRegister();
          LOperand* temp2 = TempRegister();
          LNumberTagI* result = new(zone()) LNumberTagI(value, temp1, temp2);
          return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
        }
      } else if (to.IsSmi()) {
        HValue* val = instr->value();
        LOperand* value = UseRegister(val);
        LInstruction* result = DefineAsRegister(new(zone()) LSmiTag(value));
        if (instr->CheckFlag(HValue::kCanOverflow)) {
          result = AssignEnvironment(result);
        }
        return result;
      } else {
        ASSERT(to.IsDouble());
        if (instr->value()->CheckFlag(HInstruction::kUint32)) {
          return DefineAsRegister(
              new(zone()) LUint32ToDouble(UseRegister(instr->value())));
        } else {
          return DefineAsRegister(
              new(zone()) LInteger32ToDouble(Use(instr->value())));
        }
      }
    }
    UNREACHABLE();
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoCheckHeapObject(HCheckHeapObject* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    return AssignEnvironment(new(zone()) LCheckNonSmi(value));
  }
  
  
  LInstruction* LChunkBuilder::DoCheckSmi(HCheckSmi* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    return AssignEnvironment(new(zone()) LCheckSmi(value));
  }
  
  
  LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    LInstruction* result = new(zone()) LCheckInstanceType(value);
    return AssignEnvironment(result);
  }
  
  
  LInstruction* LChunkBuilder::DoCheckValue(HCheckValue* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    return AssignEnvironment(new(zone()) LCheckValue(value));
  }
  
  
  LInstruction* LChunkBuilder::DoCheckMaps(HCheckMaps* instr) {
    LOperand* value = NULL;
    if (!instr->CanOmitMapChecks()) {
      value = UseRegisterAtStart(instr->value());
      if (instr->has_migration_target()) info()->MarkAsDeferredCalling();
    }
    LCheckMaps* result = new(zone()) LCheckMaps(value);
    if (!instr->CanOmitMapChecks()) {
      AssignEnvironment(result);
      if (instr->has_migration_target()) return AssignPointerMap(result);
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
    HValue* value = instr->value();
    Representation input_rep = value->representation();
    LOperand* reg = UseRegister(value);
    if (input_rep.IsDouble()) {
      // Revisit this decision, here and 8 lines below.
      return DefineAsRegister(new(zone()) LClampDToUint8(reg, FixedTemp(f22)));
    } else if (input_rep.IsInteger32()) {
      return DefineAsRegister(new(zone()) LClampIToUint8(reg));
    } else {
      ASSERT(input_rep.IsSmiOrTagged());
      // Register allocator doesn't (yet) support allocation of double
      // temps. Reserve f22 explicitly.
      LClampTToUint8* result = new(zone()) LClampTToUint8(reg, FixedTemp(f22));
      return AssignEnvironment(DefineAsRegister(result));
    }
  }
  
  
  LInstruction* LChunkBuilder::DoDoubleBits(HDoubleBits* instr) {
    HValue* value = instr->value();
    ASSERT(value->representation().IsDouble());
    return DefineAsRegister(new(zone()) LDoubleBits(UseRegister(value)));
  }
  
  
  LInstruction* LChunkBuilder::DoConstructDouble(HConstructDouble* instr) {
    LOperand* lo = UseRegister(instr->lo());
    LOperand* hi = UseRegister(instr->hi());
    return DefineAsRegister(new(zone()) LConstructDouble(hi, lo));
  }
  
  
  LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
    LOperand* context = info()->IsStub()
        ? UseFixed(instr->context(), cp)
        : NULL;
    LOperand* parameter_count = UseRegisterOrConstant(instr->parameter_count());
    return new(zone()) LReturn(UseFixed(instr->value(), v0), context,
                               parameter_count);
  }
  
  
  LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
    Representation r = instr->representation();
    if (r.IsSmi()) {
      return DefineAsRegister(new(zone()) LConstantS);
    } else if (r.IsInteger32()) {
      return DefineAsRegister(new(zone()) LConstantI);
    } else if (r.IsDouble()) {
      return DefineAsRegister(new(zone()) LConstantD);
    } else if (r.IsExternal()) {
      return DefineAsRegister(new(zone()) LConstantE);
    } else if (r.IsTagged()) {
      return DefineAsRegister(new(zone()) LConstantT);
    } else {
      UNREACHABLE();
      return NULL;
    }
  }
  
  
  LInstruction* LChunkBuilder::DoLoadGlobalCell(HLoadGlobalCell* instr) {
    LLoadGlobalCell* result = new(zone()) LLoadGlobalCell;
    return instr->RequiresHoleCheck()
        ? AssignEnvironment(DefineAsRegister(result))
        : DefineAsRegister(result);
  }
  
  
  LInstruction* LChunkBuilder::DoLoadGlobalGeneric(HLoadGlobalGeneric* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* global_object = UseFixed(instr->global_object(), a0);
    LLoadGlobalGeneric* result =
        new(zone()) LLoadGlobalGeneric(context, global_object);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoStoreGlobalCell(HStoreGlobalCell* instr) {
    LOperand* value = UseRegister(instr->value());
    // Use a temp to check the value in the cell in the case where we perform
    // a hole check.
    return instr->RequiresHoleCheck()
        ? AssignEnvironment(new(zone()) LStoreGlobalCell(value, TempRegister()))
        : new(zone()) LStoreGlobalCell(value, NULL);
  }
  
  
  LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
    LOperand* context = UseRegisterAtStart(instr->value());
    LInstruction* result =
        DefineAsRegister(new(zone()) LLoadContextSlot(context));
    return instr->RequiresHoleCheck() ? AssignEnvironment(result) : result;
  }
  
  
  LInstruction* LChunkBuilder::DoStoreContextSlot(HStoreContextSlot* instr) {
    LOperand* context;
    LOperand* value;
    if (instr->NeedsWriteBarrier()) {
      context = UseTempRegister(instr->context());
      value = UseTempRegister(instr->value());
    } else {
      context = UseRegister(instr->context());
      value = UseRegister(instr->value());
    }
    LInstruction* result = new(zone()) LStoreContextSlot(context, value);
    return instr->RequiresHoleCheck() ? AssignEnvironment(result) : result;
  }
  
  
  LInstruction* LChunkBuilder::DoLoadNamedField(HLoadNamedField* instr) {
    LOperand* obj = UseRegisterAtStart(instr->object());
    return DefineAsRegister(new(zone()) LLoadNamedField(obj));
  }
  
  
  LInstruction* LChunkBuilder::DoLoadNamedGeneric(HLoadNamedGeneric* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* object = UseFixed(instr->object(), a0);
    LInstruction* result =
        DefineFixed(new(zone()) LLoadNamedGeneric(context, object), v0);
    return MarkAsCall(result, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoLoadFunctionPrototype(
      HLoadFunctionPrototype* instr) {
    return AssignEnvironment(DefineAsRegister(
        new(zone()) LLoadFunctionPrototype(UseRegister(instr->function()))));
  }
  
  
  LInstruction* LChunkBuilder::DoLoadRoot(HLoadRoot* instr) {
    return DefineAsRegister(new(zone()) LLoadRoot);
  }
  
  
  LInstruction* LChunkBuilder::DoLoadKeyed(HLoadKeyed* instr) {
    ASSERT(instr->key()->representation().IsSmiOrInteger32());
    ElementsKind elements_kind = instr->elements_kind();
    LOperand* key = UseRegisterOrConstantAtStart(instr->key());
    LLoadKeyed* result = NULL;
  
    if (!instr->is_typed_elements()) {
      LOperand* obj = NULL;
      if (instr->representation().IsDouble()) {
        obj = UseRegister(instr->elements());
      } else {
        ASSERT(instr->representation().IsSmiOrTagged());
        obj = UseRegisterAtStart(instr->elements());
      }
      result = new(zone()) LLoadKeyed(obj, key);
    } else {
      ASSERT(
          (instr->representation().IsInteger32() &&
           !IsDoubleOrFloatElementsKind(instr->elements_kind())) ||
          (instr->representation().IsDouble() &&
           IsDoubleOrFloatElementsKind(instr->elements_kind())));
      LOperand* backing_store = UseRegister(instr->elements());
      result = new(zone()) LLoadKeyed(backing_store, key);
    }
  
    DefineAsRegister(result);
    // An unsigned int array load might overflow and cause a deopt, make sure it
    // has an environment.
    bool can_deoptimize = instr->RequiresHoleCheck() ||
        elements_kind == EXTERNAL_UINT32_ELEMENTS ||
        elements_kind == UINT32_ELEMENTS;
    return can_deoptimize ? AssignEnvironment(result) : result;
  }
  
  
  LInstruction* LChunkBuilder::DoLoadKeyedGeneric(HLoadKeyedGeneric* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* object = UseFixed(instr->object(), a1);
    LOperand* key = UseFixed(instr->key(), a0);
  
    LInstruction* result =
        DefineFixed(new(zone()) LLoadKeyedGeneric(context, object, key), v0);
    return MarkAsCall(result, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
    if (!instr->is_typed_elements()) {
      ASSERT(instr->elements()->representation().IsTagged());
      bool needs_write_barrier = instr->NeedsWriteBarrier();
      LOperand* object = NULL;
      LOperand* val = NULL;
      LOperand* key = NULL;
  
      if (instr->value()->representation().IsDouble()) {
        object = UseRegisterAtStart(instr->elements());
        key = UseRegisterOrConstantAtStart(instr->key());
        val = UseRegister(instr->value());
      } else {
        ASSERT(instr->value()->representation().IsSmiOrTagged());
        if (needs_write_barrier) {
          object = UseTempRegister(instr->elements());
          val = UseTempRegister(instr->value());
          key = UseTempRegister(instr->key());
        } else {
          object = UseRegisterAtStart(instr->elements());
          val = UseRegisterAtStart(instr->value());
          key = UseRegisterOrConstantAtStart(instr->key());
        }
      }
  
      return new(zone()) LStoreKeyed(object, key, val);
    }
  
    ASSERT(
        (instr->value()->representation().IsInteger32() &&
         !IsDoubleOrFloatElementsKind(instr->elements_kind())) ||
        (instr->value()->representation().IsDouble() &&
         IsDoubleOrFloatElementsKind(instr->elements_kind())));
    ASSERT((instr->is_fixed_typed_array() &&
            instr->elements()->representation().IsTagged()) ||
           (instr->is_external() &&
            instr->elements()->representation().IsExternal()));
    LOperand* val = UseRegister(instr->value());
    LOperand* key = UseRegisterOrConstantAtStart(instr->key());
    LOperand* backing_store = UseRegister(instr->elements());
    return new(zone()) LStoreKeyed(backing_store, key, val);
  }
  
  
  LInstruction* LChunkBuilder::DoStoreKeyedGeneric(HStoreKeyedGeneric* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* obj = UseFixed(instr->object(), a2);
    LOperand* key = UseFixed(instr->key(), a1);
    LOperand* val = UseFixed(instr->value(), a0);
  
    ASSERT(instr->object()->representation().IsTagged());
    ASSERT(instr->key()->representation().IsTagged());
    ASSERT(instr->value()->representation().IsTagged());
  
    return MarkAsCall(
        new(zone()) LStoreKeyedGeneric(context, obj, key, val), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoTransitionElementsKind(
      HTransitionElementsKind* instr) {
    LOperand* object = UseRegister(instr->object());
    if (IsSimpleMapChangeTransition(instr->from_kind(), instr->to_kind())) {
      LOperand* new_map_reg = TempRegister();
      LTransitionElementsKind* result =
          new(zone()) LTransitionElementsKind(object, NULL, new_map_reg);
      return result;
    } else {
      LOperand* context = UseFixed(instr->context(), cp);
      LTransitionElementsKind* result =
          new(zone()) LTransitionElementsKind(object, context, NULL);
      return AssignPointerMap(result);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoTrapAllocationMemento(
      HTrapAllocationMemento* instr) {
    LOperand* object = UseRegister(instr->object());
    LOperand* temp = TempRegister();
    LTrapAllocationMemento* result =
        new(zone()) LTrapAllocationMemento(object, temp);
    return AssignEnvironment(result);
  }
  
  
  LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
    bool is_in_object = instr->access().IsInobject();
    bool needs_write_barrier = instr->NeedsWriteBarrier();
    bool needs_write_barrier_for_map = instr->has_transition() &&
        instr->NeedsWriteBarrierForMap();
  
    LOperand* obj;
    if (needs_write_barrier) {
      obj = is_in_object
          ? UseRegister(instr->object())
          : UseTempRegister(instr->object());
    } else {
      obj = needs_write_barrier_for_map
          ? UseRegister(instr->object())
          : UseRegisterAtStart(instr->object());
    }
  
    LOperand* val;
    if (needs_write_barrier || instr->field_representation().IsSmi()) {
      val = UseTempRegister(instr->value());
    } else if (instr->field_representation().IsDouble()) {
      val = UseRegisterAtStart(instr->value());
    } else {
      val = UseRegister(instr->value());
    }
  
    // We need a temporary register for write barrier of the map field.
    LOperand* temp = needs_write_barrier_for_map ? TempRegister() : NULL;
  
    LStoreNamedField* result = new(zone()) LStoreNamedField(obj, val, temp);
    if (instr->field_representation().IsHeapObject()) {
      if (!instr->value()->type().IsHeapObject()) {
        return AssignEnvironment(result);
      }
    }
    return result;
  }
  
  
  LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* obj = UseFixed(instr->object(), a1);
    LOperand* val = UseFixed(instr->value(), a0);
  
    LInstruction* result = new(zone()) LStoreNamedGeneric(context, obj, val);
    return MarkAsCall(result, instr);
  }
  
  
  LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* left = UseFixed(instr->left(), a1);
    LOperand* right = UseFixed(instr->right(), a0);
    return MarkAsCall(
        DefineFixed(new(zone()) LStringAdd(context, left, right), v0),
        instr);
  }
  
  
  LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
    LOperand* string = UseTempRegister(instr->string());
    LOperand* index = UseTempRegister(instr->index());
    LOperand* context = UseAny(instr->context());
    LStringCharCodeAt* result =
        new(zone()) LStringCharCodeAt(context, string, index);
    return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
  }
  
  
  LInstruction* LChunkBuilder::DoStringCharFromCode(HStringCharFromCode* instr) {
    LOperand* char_code = UseRegister(instr->value());
    LOperand* context = UseAny(instr->context());
    LStringCharFromCode* result =
        new(zone()) LStringCharFromCode(context, char_code);
    return AssignPointerMap(DefineAsRegister(result));
  }
  
  
  LInstruction* LChunkBuilder::DoAllocate(HAllocate* instr) {
    info()->MarkAsDeferredCalling();
    LOperand* context = UseAny(instr->context());
    LOperand* size = instr->size()->IsConstant()
        ? UseConstant(instr->size())
        : UseTempRegister(instr->size());
    LOperand* temp1 = TempRegister();
    LOperand* temp2 = TempRegister();
    LAllocate* result = new(zone()) LAllocate(context, size, temp1, temp2);
    return AssignPointerMap(DefineAsRegister(result));
  }
  
  
  LInstruction* LChunkBuilder::DoRegExpLiteral(HRegExpLiteral* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    return MarkAsCall(
        DefineFixed(new(zone()) LRegExpLiteral(context), v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoFunctionLiteral(HFunctionLiteral* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    return MarkAsCall(
        DefineFixed(new(zone()) LFunctionLiteral(context), v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoOsrEntry(HOsrEntry* instr) {
    ASSERT(argument_count_ == 0);
    allocator_->MarkAsOsrEntry();
    current_block_->last_environment()->set_ast_id(instr->ast_id());
    return AssignEnvironment(new(zone()) LOsrEntry);
  }
  
  
  LInstruction* LChunkBuilder::DoParameter(HParameter* instr) {
    LParameter* result = new(zone()) LParameter;
    if (instr->kind() == HParameter::STACK_PARAMETER) {
      int spill_index = chunk()->GetParameterStackSlot(instr->index());
      return DefineAsSpilled(result, spill_index);
    } else {
      ASSERT(info()->IsStub());
      CodeStubInterfaceDescriptor* descriptor =
          info()->code_stub()->GetInterfaceDescriptor(info()->isolate());
      int index = static_cast<int>(instr->index());
      Register reg = descriptor->GetParameterRegister(index);
      return DefineFixed(result, reg);
    }
  }
  
  
  LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
    // Use an index that corresponds to the location in the unoptimized frame,
    // which the optimized frame will subsume.
    int env_index = instr->index();
    int spill_index = 0;
    if (instr->environment()->is_parameter_index(env_index)) {
      spill_index = chunk()->GetParameterStackSlot(env_index);
    } else {
      spill_index = env_index - instr->environment()->first_local_index();
      if (spill_index > LUnallocated::kMaxFixedSlotIndex) {
        Abort(kTooManySpillSlotsNeededForOSR);
        spill_index = 0;
      }
    }
    return DefineAsSpilled(new(zone()) LUnknownOSRValue, spill_index);
  }
  
  
  LInstruction* LChunkBuilder::DoCallStub(HCallStub* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    return MarkAsCall(DefineFixed(new(zone()) LCallStub(context), v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoArgumentsObject(HArgumentsObject* instr) {
    // There are no real uses of the arguments object.
    // arguments.length and element access are supported directly on
    // stack arguments, and any real arguments object use causes a bailout.
    // So this value is never used.
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoCapturedObject(HCapturedObject* instr) {
    instr->ReplayEnvironment(current_block_->last_environment());
  
    // There are no real uses of a captured object.
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
    info()->MarkAsRequiresFrame();
    LOperand* args = UseRegister(instr->arguments());
    LOperand* length = UseRegisterOrConstantAtStart(instr->length());
    LOperand* index = UseRegisterOrConstantAtStart(instr->index());
    return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length, index));
  }
  
  
  LInstruction* LChunkBuilder::DoToFastProperties(HToFastProperties* instr) {
    LOperand* object = UseFixed(instr->value(), a0);
    LToFastProperties* result = new(zone()) LToFastProperties(object);
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoTypeof(HTypeof* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LTypeof* result = new(zone()) LTypeof(context, UseFixed(instr->value(), a0));
    return MarkAsCall(DefineFixed(result, v0), instr);
  }
  
  
  LInstruction* LChunkBuilder::DoTypeofIsAndBranch(HTypeofIsAndBranch* instr) {
    LInstruction* goto_instr = CheckElideControlInstruction(instr);
    if (goto_instr != NULL) return goto_instr;
  
    return new(zone()) LTypeofIsAndBranch(UseTempRegister(instr->value()));
  }
  
  
  LInstruction* LChunkBuilder::DoIsConstructCallAndBranch(
      HIsConstructCallAndBranch* instr) {
    return new(zone()) LIsConstructCallAndBranch(TempRegister());
  }
  
  
  LInstruction* LChunkBuilder::DoSimulate(HSimulate* instr) {
    instr->ReplayEnvironment(current_block_->last_environment());
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoStackCheck(HStackCheck* instr) {
    if (instr->is_function_entry()) {
      LOperand* context = UseFixed(instr->context(), cp);
      return MarkAsCall(new(zone()) LStackCheck(context), instr);
    } else {
      ASSERT(instr->is_backwards_branch());
      LOperand* context = UseAny(instr->context());
      return AssignEnvironment(
          AssignPointerMap(new(zone()) LStackCheck(context)));
    }
  }
  
  
  LInstruction* LChunkBuilder::DoEnterInlined(HEnterInlined* instr) {
    HEnvironment* outer = current_block_->last_environment();
    HConstant* undefined = graph()->GetConstantUndefined();
    HEnvironment* inner = outer->CopyForInlining(instr->closure(),
                                                 instr->arguments_count(),
                                                 instr->function(),
                                                 undefined,
                                                 instr->inlining_kind());
    // Only replay binding of arguments object if it wasn't removed from graph.
    if (instr->arguments_var() != NULL && instr->arguments_object()->IsLinked()) {
      inner->Bind(instr->arguments_var(), instr->arguments_object());
    }
    inner->set_entry(instr);
    current_block_->UpdateEnvironment(inner);
    chunk_->AddInlinedClosure(instr->closure());
    return NULL;
  }
  
  
  LInstruction* LChunkBuilder::DoLeaveInlined(HLeaveInlined* instr) {
    LInstruction* pop = NULL;
  
    HEnvironment* env = current_block_->last_environment();
  
    if (env->entry()->arguments_pushed()) {
      int argument_count = env->arguments_environment()->parameter_count();
      pop = new(zone()) LDrop(argument_count);
      ASSERT(instr->argument_delta() == -argument_count);
    }
  
    HEnvironment* outer = current_block_->last_environment()->
        DiscardInlined(false);
    current_block_->UpdateEnvironment(outer);
  
    return pop;
  }
  
  
  LInstruction* LChunkBuilder::DoForInPrepareMap(HForInPrepareMap* instr) {
    LOperand* context = UseFixed(instr->context(), cp);
    LOperand* object = UseFixed(instr->enumerable(), a0);
    LForInPrepareMap* result = new(zone()) LForInPrepareMap(context, object);
    return MarkAsCall(DefineFixed(result, v0), instr, CAN_DEOPTIMIZE_EAGERLY);
  }
  
  
  LInstruction* LChunkBuilder::DoForInCacheArray(HForInCacheArray* instr) {
    LOperand* map = UseRegister(instr->map());
    return AssignEnvironment(DefineAsRegister(new(zone()) LForInCacheArray(map)));
  }
  
  
  LInstruction* LChunkBuilder::DoCheckMapValue(HCheckMapValue* instr) {
    LOperand* value = UseRegisterAtStart(instr->value());
    LOperand* map = UseRegisterAtStart(instr->map());
    return AssignEnvironment(new(zone()) LCheckMapValue(value, map));
  }
  
  
  LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
    LOperand* object = UseRegister(instr->object());
    LOperand* index = UseRegister(instr->index());
    return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
  }
  
  
  } }  // namespace v8::internal
  