[turbofan] Eliminate redundant ChangeTaggedSignedToInt32.

src/compiler/simplified-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/simplified-operator-reducer.h"
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 71 matching lines @@
       if (m.HasValue()) return ReplaceFloat64(m.Value());
       if (m.IsChangeFloat64ToTagged()) return Replace(m.node()->InputAt(0));
       if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged()) {
         return Change(node, machine()->ChangeInt32ToFloat64(), m.InputAt(0));
       }
       if (m.IsChangeUint32ToTagged()) {
         return Change(node, machine()->ChangeUint32ToFloat64(), m.InputAt(0));
       }
       break;
     }
+    case IrOpcode::kChangeTaggedSignedToInt32:
     case IrOpcode::kChangeTaggedToInt32: {
       NumberMatcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceInt32(DoubleToInt32(m.Value()));
       if (m.IsChangeFloat64ToTagged()) {
         return Change(node, machine()->ChangeFloat64ToInt32(), m.InputAt(0));
       }
       if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged()) {
         return Replace(m.InputAt(0));
       }
       break;
@@ skipping 148 matching lines @@
   return jsgraph()->isolate();
 }
 
 MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8