[Isolates] Merge 6500:6700 from bleeding_edge to isolates.

src/arm/lithium-arm.cc

 // Copyright 2011 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 "lithium-allocator-inl.h"
 #include "arm/lithium-arm.h"
 #include "arm/lithium-codegen-arm.h"
 
 namespace v8 {
 namespace internal {
 
 #define DEFINE_COMPILE(type)                            \
   void L##type::CompileToNative(LCodeGen* generator) {  \
     generator->Do##type(this);                          \
   }
@@ skipping 11 matching lines @@
 
 
 void LOsrEntry::MarkSpilledRegister(int allocation_index,
                                     LOperand* spill_operand) {
   ASSERT(spill_operand->IsStackSlot());
   ASSERT(register_spills_[allocation_index] == NULL);
   register_spills_[allocation_index] = spill_operand;
 }
 
 
+#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 can use either fixed register or have a short lifetime (be
+  // used at start of the instruction).
+  ASSERT(Output() == NULL ||
+         LUnallocated::cast(Output())->HasFixedPolicy() ||
+         !LUnallocated::cast(Output())->HasRegisterPolicy());
+  for (UseIterator it(this); it.HasNext(); it.Advance()) {
+    LOperand* operand = it.Next();
+    ASSERT(LUnallocated::cast(operand)->HasFixedPolicy() ||
+           LUnallocated::cast(operand)->IsUsedAtStart() ||
+           !LUnallocated::cast(operand)->HasRegisterPolicy());
+  }
+  for (TempIterator it(this); it.HasNext(); it.Advance()) {
+    LOperand* operand = it.Next();
+    ASSERT(LUnallocated::cast(operand)->HasFixedPolicy() ||
+           !LUnallocated::cast(operand)->HasRegisterPolicy());
+  }
+}
+#endif
+
+
 void LOsrEntry::MarkSpilledDoubleRegister(int allocation_index,
                                           LOperand* spill_operand) {
   ASSERT(spill_operand->IsDoubleStackSlot());
   ASSERT(double_register_spills_[allocation_index] == NULL);
   double_register_spills_[allocation_index] = spill_operand;
 }
 
 
 void LInstruction::PrintTo(StringStream* stream) {
   stream->Add("%s ", this->Mnemonic());
-  if (HasResult()) {
-    PrintOutputOperandTo(stream);
-  }
+
+  PrintOutputOperandTo(stream);
 
   PrintDataTo(stream);
 
   if (HasEnvironment()) {
     stream->Add(" ");
     environment()->PrintTo(stream);
   }
 
   if (HasPointerMap()) {
     stream->Add(" ");
@@ skipping 69 matching lines @@
 }
 
 
 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";
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
 
 void LGoto::PrintDataTo(StringStream* stream) {
   stream->Add("B%d", block_id());
 }
@@ skipping 80 matching lines @@
 }
 
 
 void LUnaryMathOperation::PrintDataTo(StringStream* stream) {
   stream->Add("/%s ", hydrogen()->OpName());
   InputAt(0)->PrintTo(stream);
 }
 
 
 void LLoadContextSlot::PrintDataTo(StringStream* stream) {
-  stream->Add("(%d, %d)", context_chain_length(), slot_index());
+  InputAt(0)->PrintTo(stream);
+  stream->Add("[%d]", slot_index());
+}
+
+
+void LStoreContextSlot::PrintDataTo(StringStream* stream) {
+  InputAt(0)->PrintTo(stream);
+  stream->Add("[%d] <- ", slot_index());
+  InputAt(1)->PrintTo(stream);
 }
 
 
 void LCallKeyed::PrintDataTo(StringStream* stream) {
   stream->Add("[r2] #%d / ", arity());
 }
 
 
 void LCallNamed::PrintDataTo(StringStream* stream) {
   SmartPointer<char> name_string = name()->ToCString();
@@ skipping 111 matching lines @@
 
         if (can_eliminate) {
           label->set_replacement(GetLabel(goto_instr->block_id()));
         }
       }
     }
   }
 }
 
 
-int LChunk::AddInstruction(LInstruction* instr, HBasicBlock* block) {
+void LChunk::AddInstruction(LInstruction* instr, HBasicBlock* block) {
   LGap* gap = new LGap(block);
   int index = -1;
   if (instr->IsControl()) {
     instructions_.Add(gap);
     index = instructions_.length();
     instructions_.Add(instr);
   } else {
     index = instructions_.length();
     instructions_.Add(instr);
     instructions_.Add(gap);
   }
   if (instr->HasPointerMap()) {
     pointer_maps_.Add(instr->pointer_map());
     instr->pointer_map()->set_lithium_position(index);
   }
-  return index;
 }
 
 
 LConstantOperand* LChunk::DefineConstantOperand(HConstant* constant) {
   return LConstantOperand::Create(constant->id());
 }
 
 
 int LChunk::GetParameterStackSlot(int index) const {
   // The receiver is at index 0, the first parameter at index 1, so we
@@ skipping 228 matching lines @@
 
 LInstruction* LChunkBuilder::AssignEnvironment(LInstruction* instr) {
   HEnvironment* hydrogen_env = current_block_->last_environment();
   instr->set_environment(CreateEnvironment(hydrogen_env));
   return instr;
 }
 
 
 LInstruction* LChunkBuilder::SetInstructionPendingDeoptimizationEnvironment(
     LInstruction* instr, int ast_id) {
-  ASSERT(instructions_pending_deoptimization_environment_ == NULL);
+  ASSERT(instruction_pending_deoptimization_environment_ == NULL);
   ASSERT(pending_deoptimization_ast_id_ == AstNode::kNoNumber);
-  instructions_pending_deoptimization_environment_ = instr;
+  instruction_pending_deoptimization_environment_ = instr;
   pending_deoptimization_ast_id_ = ast_id;
   return instr;
 }
 
 
 void LChunkBuilder::ClearInstructionPendingDeoptimizationEnvironment() {
-  instructions_pending_deoptimization_environment_ = NULL;
+  instruction_pending_deoptimization_environment_ = NULL;
   pending_deoptimization_ast_id_ = AstNode::kNoNumber;
 }
 
 
 LInstruction* LChunkBuilder::MarkAsCall(LInstruction* instr,
                                         HInstruction* hinstr,
                                         CanDeoptimize can_deoptimize) {
-  allocator_->MarkAsCall();
+#ifdef DEBUG
+  instr->VerifyCall();
+#endif
+  instr->MarkAsCall();
   instr = AssignPointerMap(instr);
 
   if (hinstr->HasSideEffects()) {
     ASSERT(hinstr->next()->IsSimulate());
     HSimulate* sim = HSimulate::cast(hinstr->next());
     instr = SetInstructionPendingDeoptimizationEnvironment(
         instr, sim->ast_id());
   }
 
   // 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->HasSideEffects();
   if (needs_environment && !instr->HasEnvironment()) {
     instr = AssignEnvironment(instr);
   }
 
   return instr;
 }
 
 
 LInstruction* LChunkBuilder::MarkAsSaveDoubles(LInstruction* instr) {
-  allocator_->MarkAsSaveDoubles();
+  instr->MarkAsSaveDoubles();
   return instr;
 }
 
 
 LInstruction* LChunkBuilder::AssignPointerMap(LInstruction* instr) {
   ASSERT(!instr->HasPointerMap());
   instr->set_pointer_map(new LPointerMap(position_));
   return instr;
 }
 
@@ skipping 24 matching lines @@
 }
 
 
 LInstruction* LChunkBuilder::DoDeoptimize(HDeoptimize* instr) {
   return AssignEnvironment(new LDeoptimize);
 }
 
 
 LInstruction* LChunkBuilder::DoBit(Token::Value op,
                                    HBitwiseBinaryOperation* instr) {
-  ASSERT(instr->representation().IsInteger32());
-  ASSERT(instr->left()->representation().IsInteger32());
-  ASSERT(instr->right()->representation().IsInteger32());
+  if (instr->representation().IsInteger32()) {
+    ASSERT(instr->left()->representation().IsInteger32());
+    ASSERT(instr->right()->representation().IsInteger32());
 
-  LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
-  LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
-  return DefineSameAsFirst(new LBitI(op, left, right));
+    LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
+    LOperand* right = UseOrConstantAtStart(instr->MostConstantOperand());
+    return DefineSameAsFirst(new LBitI(op, left, right));
+  } else {
+    ASSERT(instr->representation().IsTagged());
+    ASSERT(instr->left()->representation().IsTagged());
+    ASSERT(instr->right()->representation().IsTagged());
+
+    LOperand* left = UseFixed(instr->left(), r1);
+    LOperand* right = UseFixed(instr->right(), r0);
+    LArithmeticT* result = new LArithmeticT(op, left, right);
+    return MarkAsCall(DefineFixed(result, r0), instr);
+  }
 }
 
 
 LInstruction* LChunkBuilder::DoShift(Token::Value op,
                                      HBitwiseBinaryOperation* instr) {
   ASSERT(instr->representation().IsInteger32());
   ASSERT(instr->OperandAt(0)->representation().IsInteger32());
   ASSERT(instr->OperandAt(1)->representation().IsInteger32());
   LOperand* left = UseRegisterAtStart(instr->OperandAt(0));
 
@@ skipping 118 matching lines @@
   }
   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;
-  allocator_->BeginInstruction();
   if (current->has_position()) position_ = current->position();
   LInstruction* instr = current->CompileToLithium(this);
 
   if (instr != NULL) {
     if (FLAG_stress_pointer_maps && !instr->HasPointerMap()) {
       instr = AssignPointerMap(instr);
     }
     if (FLAG_stress_environments && !instr->HasEnvironment()) {
       instr = AssignEnvironment(instr);
     }
     if (current->IsTest() && !instr->IsGoto()) {
       ASSERT(instr->IsControl());
       HTest* test = HTest::cast(current);
       instr->set_hydrogen_value(test->value());
       HBasicBlock* first = test->FirstSuccessor();
       HBasicBlock* second = test->SecondSuccessor();
       ASSERT(first != NULL && second != NULL);
       instr->SetBranchTargets(first->block_id(), second->block_id());
     } else {
       instr->set_hydrogen_value(current);
     }
 
-    int index = chunk_->AddInstruction(instr, current_block_);
-    allocator_->SummarizeInstruction(index);
-  } else {
-    // This instruction should be omitted.
-    allocator_->OmitInstruction();
+    chunk_->AddInstruction(instr, current_block_);
   }
   current_instruction_ = old_current;
 }
 
 
 LEnvironment* LChunkBuilder::CreateEnvironment(HEnvironment* hydrogen_env) {
   if (hydrogen_env == NULL) return NULL;
 
   LEnvironment* outer = CreateEnvironment(hydrogen_env->outer());
   int ast_id = hydrogen_env->ast_id();
@@ skipping 93 matching lines @@
 
       LOperand* temp = TempRegister();
       return new LIsObjectAndBranch(UseRegisterAtStart(compare->value()), temp);
     } else if (v->IsCompareJSObjectEq()) {
       HCompareJSObjectEq* compare = HCompareJSObjectEq::cast(v);
       return new LCmpJSObjectEqAndBranch(UseRegisterAtStart(compare->left()),
                                          UseRegisterAtStart(compare->right()));
     } else if (v->IsInstanceOf()) {
       HInstanceOf* instance_of = HInstanceOf::cast(v);
       LInstruction* result =
-          new LInstanceOfAndBranch(Use(instance_of->left()),
-                                   Use(instance_of->right()));
+          new LInstanceOfAndBranch(UseFixed(instance_of->left(), r0),
+                                   UseFixed(instance_of->right(), r1));
       return MarkAsCall(result, instr);
     } else if (v->IsTypeofIs()) {
       HTypeofIs* typeof_is = HTypeofIs::cast(v);
       return new LTypeofIsAndBranch(UseTempRegister(typeof_is->value()));
+    } else if (v->IsIsConstructCall()) {
+      return new LIsConstructCallAndBranch(TempRegister());
     } else {
       if (v->IsConstant()) {
         if (HConstant::cast(v)->handle()->IsTrue()) {
           return new LGoto(instr->FirstSuccessor()->block_id());
         } else if (HConstant::cast(v)->handle()->IsFalse()) {
           return new LGoto(instr->SecondSuccessor()->block_id());
         }
       }
       Abort("Undefined compare before branch");
       return NULL;
@@ skipping 51 matching lines @@
 }
 
 
 LInstruction* LChunkBuilder::DoPushArgument(HPushArgument* instr) {
   ++argument_count_;
   LOperand* argument = Use(instr->argument());
   return new LPushArgument(argument);
 }
 
 
+LInstruction* LChunkBuilder::DoContext(HContext* instr) {
+  return DefineAsRegister(new LContext);
+}
+
+
+LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
+  LOperand* context = UseRegisterAtStart(instr->value());
+  return DefineAsRegister(new LOuterContext(context));
+}
+
+
 LInstruction* LChunkBuilder::DoGlobalObject(HGlobalObject* instr) {
-  return DefineAsRegister(new LGlobalObject);
+  LOperand* context = UseRegisterAtStart(instr->value());
+  return DefineAsRegister(new LGlobalObject(context));
 }
 
 
 LInstruction* LChunkBuilder::DoGlobalReceiver(HGlobalReceiver* instr) {
-  return DefineAsRegister(new LGlobalReceiver);
+  LOperand* global_object = UseRegisterAtStart(instr->value());
+  return DefineAsRegister(new LGlobalReceiver(global_object));
 }
 
 
 LInstruction* LChunkBuilder::DoCallConstantFunction(
     HCallConstantFunction* instr) {
   argument_count_ -= instr->argument_count();
   return MarkAsCall(DefineFixed(new LCallConstantFunction, r0), instr);
 }
 
 
@@ skipping 116 matching lines @@
 
 LInstruction* LChunkBuilder::DoDiv(HDiv* instr) {
   if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::DIV, instr);
   } else if (instr->representation().IsInteger32()) {
     // TODO(1042) The fixed register allocation
     // is needed because we call GenericBinaryOpStub from
     // the generated code, which requires registers r0
     // and r1 to be used. We should remove that
     // when we provide a native implementation.
-    LOperand* value = UseFixed(instr->left(), r0);
+    LOperand* dividend = UseFixed(instr->left(), r0);
     LOperand* divisor = UseFixed(instr->right(), r1);
     return AssignEnvironment(AssignPointerMap(
-             DefineFixed(new LDivI(value, divisor), r0)));
+             DefineFixed(new LDivI(dividend, divisor), r0)));
   } else {
     return DoArithmeticT(Token::DIV, instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoMod(HMod* instr) {
   if (instr->representation().IsInteger32()) {
     // TODO(1042) The fixed register allocation
     // is needed because we call GenericBinaryOpStub from
@@ skipping 191 matching lines @@
   return AssignEnvironment(DefineSameAsFirst(result));
 }
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
   return AssignEnvironment(new LBoundsCheck(UseRegisterAtStart(instr->index()),
                                             UseRegister(instr->length())));
 }
 
 
+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::DoThrow(HThrow* instr) {
   LOperand* value = UseFixed(instr->value(), r0);
   return MarkAsCall(new LThrow(value), instr);
 }
 
 
 LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   Representation from = instr->from();
   Representation to = instr->to();
   if (from.IsTagged()) {
@@ skipping 24 matching lines @@
 
       // Make sure that the temp and result_temp registers are
       // different.
       LUnallocated* result_temp = TempRegister();
       LNumberTagD* result = new LNumberTagD(value, temp1, temp2);
       Define(result, result_temp);
       return AssignPointerMap(result);
     } else {
       ASSERT(to.IsInteger32());
       LOperand* value = UseRegister(instr->value());
-      LDoubleToI* res = new LDoubleToI(value);
+      LDoubleToI* res = new LDoubleToI(value, TempRegister());
       return AssignEnvironment(DefineAsRegister(res));
     }
   } else if (from.IsInteger32()) {
     if (to.IsTagged()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->HasRange() && val->range()->IsInSmiRange()) {
         return DefineSameAsFirst(new LSmiTag(value));
       } else {
         LNumberTagI* result = new LNumberTagI(value);
@@ skipping 51 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   return new LReturn(UseFixed(instr->value(), r0));
 }
 
 
 LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
   Representation r = instr->representation();
   if (r.IsInteger32()) {
-    int32_t value = instr->Integer32Value();
-    return DefineAsRegister(new LConstantI(value));
+    return DefineAsRegister(new LConstantI);
   } else if (r.IsDouble()) {
-    double value = instr->DoubleValue();
-    return DefineAsRegister(new LConstantD(value));
+    return DefineAsRegister(new LConstantD);
   } else if (r.IsTagged()) {
-    return DefineAsRegister(new LConstantT(instr->handle()));
+    return DefineAsRegister(new LConstantT);
   } else {
     UNREACHABLE();
     return NULL;
   }
 }
 
 
 LInstruction* LChunkBuilder::DoLoadGlobal(HLoadGlobal* instr) {
   LLoadGlobal* result = new LLoadGlobal();
   return instr->check_hole_value()
       ? AssignEnvironment(DefineAsRegister(result))
       : DefineAsRegister(result);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreGlobal(HStoreGlobal* instr) {
-  return new LStoreGlobal(UseRegisterAtStart(instr->value()));
+  if (instr->check_hole_value()) {
+    LOperand* temp = TempRegister();
+    LOperand* value = UseRegister(instr->value());
+    return AssignEnvironment(new LStoreGlobal(value, temp));
+  } else {
+    LOperand* value = UseRegisterAtStart(instr->value());
+    return new LStoreGlobal(value, NULL);
+  }
 }
 
 
 LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
-  return DefineAsRegister(new LLoadContextSlot);
+  LOperand* context = UseRegisterAtStart(instr->value());
+  return DefineAsRegister(new LLoadContextSlot(context));
+}
+
+
+LInstruction* LChunkBuilder::DoStoreContextSlot(HStoreContextSlot* instr) {
+  LOperand* context = UseTempRegister(instr->context());
+  LOperand* value;
+  if (instr->NeedsWriteBarrier()) {
+    value = UseTempRegister(instr->value());
+  } else {
+    value = UseRegister(instr->value());
+  }
+  return new LStoreContextSlot(context, value);
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedField(HLoadNamedField* instr) {
   return DefineAsRegister(
       new LLoadNamedField(UseRegisterAtStart(instr->object())));
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedGeneric(HLoadNamedGeneric* instr) {
@@ skipping 179 matching lines @@
 LInstruction* LChunkBuilder::DoTypeof(HTypeof* instr) {
   LTypeof* result = new LTypeof(UseRegisterAtStart(instr->value()));
   return MarkAsCall(DefineFixed(result, r0), instr);
 }
 
 
 LInstruction* LChunkBuilder::DoTypeofIs(HTypeofIs* instr) {
   return DefineSameAsFirst(new LTypeofIs(UseRegister(instr->value())));
 }
 
+
+LInstruction* LChunkBuilder::DoIsConstructCall(HIsConstructCall* instr) {
+  return DefineAsRegister(new LIsConstructCall());
+}
+
+
 LInstruction* LChunkBuilder::DoSimulate(HSimulate* instr) {
   HEnvironment* env = current_block_->last_environment();
   ASSERT(env != NULL);
 
   env->set_ast_id(instr->ast_id());
 
   env->Drop(instr->pop_count());
   for (int i = 0; i < instr->values()->length(); ++i) {
     HValue* value = instr->values()->at(i);
     if (instr->HasAssignedIndexAt(i)) {
       env->Bind(instr->GetAssignedIndexAt(i), value);
     } else {
       env->Push(value);
     }
   }
 
   ASSERT(env->length() == instr->environment_length());
 
   // If there is an instruction pending deoptimization environment create a
   // lazy bailout instruction to capture the environment.
   if (pending_deoptimization_ast_id_ == instr->ast_id()) {
     LInstruction* result = new LLazyBailout;
     result = AssignEnvironment(result);
-    instructions_pending_deoptimization_environment_->
+    instruction_pending_deoptimization_environment_->
         set_deoptimization_environment(result->environment());
     ClearInstructionPendingDeoptimizationEnvironment();
     return result;
   }
 
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoStackCheck(HStackCheck* instr) {
@@ skipping 15 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLeaveInlined(HLeaveInlined* instr) {
   HEnvironment* outer = current_block_->last_environment()->outer();
   current_block_->UpdateEnvironment(outer);
   return NULL;
 }
 
 
 } }  // namespace v8::internal