[turbofan] Run DeadCodeElimination together with the advanced reducers.

src/compiler/common-operator-reducer.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/common-operator-reducer.h"
 
 #include <algorithm>
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
@@ skipping 50 matching lines @@
   return NoChange();
 }
 
 
 Reduction CommonOperatorReducer::ReduceBranch(Node* node) {
   DCHECK_EQ(IrOpcode::kBranch, node->opcode());
   Node* const cond = node->InputAt(0);
   Decision const decision = DecideCondition(cond);
   if (decision == Decision::kUnknown) return NoChange();
   Node* const control = node->InputAt(1);
-  node->set_op(common()->Dead());
-  node->TrimInputCount(0);
+  if (!dead_.is_set()) dead_.set(graph()->NewNode(common()->Dead()));
   for (Node* const use : node->uses()) {
     switch (use->opcode()) {
       case IrOpcode::kIfTrue:
-        Replace(use, (decision == Decision::kTrue) ? control : node);
+        Replace(use, (decision == Decision::kTrue) ? control : dead_.get());
         break;
       case IrOpcode::kIfFalse:
-        Replace(use, (decision == Decision::kFalse) ? control : node);
+        Replace(use, (decision == Decision::kFalse) ? control : dead_.get());
         break;
       default:
         UNREACHABLE();
     }
   }
-  return Changed(node);
+  return Replace(dead_.get());
 }
 
 
 Reduction CommonOperatorReducer::ReduceMerge(Node* node) {
   DCHECK_EQ(IrOpcode::kMerge, node->opcode());
   //
   // Check if this is a merge that belongs to an unused diamond, which means
   // that:
   //
   //  a) the {Merge} has no {Phi} or {EffectPhi} uses, and
@@ skipping 207 matching lines @@
   node->set_op(op);
   node->ReplaceInput(0, a);
   node->ReplaceInput(1, b);
   node->TrimInputCount(2);
   return Changed(node);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8