[turbofan] Optimize tagged conversion based on type.

src/compiler/pipeline.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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/adapters.h"
@@ skipping 1263 matching lines @@
 
   // Select representations.
   Run<RepresentationSelectionPhase>();
   RunPrintAndVerify("Representations selected");
 
   // Run early optimization pass.
   Run<EarlyOptimizationPhase>();
   RunPrintAndVerify("Early optimized");
 
   if (info()->is_effect_scheduling_enabled()) {
-    // TODO(jarin) Run value numbering for the representation changes.
     Run<EffectControlLinearizationPhase>();
     RunPrintAndVerify("Effect and control linearized");
   }
 
   Run<BranchEliminationPhase>();
   RunPrintAndVerify("Branch conditions eliminated");
 
   // Optimize control flow.
   if (FLAG_turbo_cf_optimization) {
     Run<ControlFlowOptimizationPhase>();
@@ skipping 298 matching lines @@
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 Isolate* Pipeline::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8