[turbofan] Proper dead code elimination as regular reducer.

src/compiler/simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 479 matching lines @@
 
   // Dispatching routine for visiting the node {node} with the usage {use}.
   // Depending on the operator, propagate new usage info to the inputs.
   void VisitNode(Node* node, MachineTypeUnion use,
                  SimplifiedLowering* lowering) {
     switch (node->opcode()) {
       //------------------------------------------------------------------
       // Common operators.
       //------------------------------------------------------------------
       case IrOpcode::kStart:
-      case IrOpcode::kDeadControl:
+      case IrOpcode::kDead:
         return VisitLeaf(node, 0);
       case IrOpcode::kParameter: {
         // TODO(titzer): use representation from linkage.
         Type* upper = NodeProperties::GetBounds(node).upper;
         ProcessInput(node, 0, 0);
         SetOutput(node, kRepTagged | changer_->TypeFromUpperBound(upper));
         return;
       }
       case IrOpcode::kInt32Constant:
         return VisitLeaf(node, kRepWord32);
@@ skipping 1081 matching lines @@
 
 void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) {
   node->set_op(machine()->IntLessThanOrEqual());
   node->ReplaceInput(0, StringComparison(node, true));
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8