[turbofan] Remove a bit of dead code from simplified lowering.

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 313 matching lines @@
       // only float64 uses.
       return kRepFloat64;
     } else if ((use & kRepMask) == kRepTagged) {
       // only tagged uses.
       return kRepTagged;
     } else if (upper->Is(Type::Integral32())) {
       // Integer within [-2^31, 2^32[ range.
       if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) {
         // multiple uses, but we are within 32 bits range => pick kRepWord32.
         return kRepWord32;
-      } else if (((use & kRepMask) == kRepWord32 &&
-                  !CanObserveNonWord32(use)) ||
-                 (use & kTypeMask) == kTypeInt32 ||
+      } else if ((use & kTypeMask) == kTypeInt32 ||
                  (use & kTypeMask) == kTypeUint32) {
         // We only use 32 bits or we use the result consistently.
         return kRepWord32;
       } else {
         return kRepFloat64;
       }
     } else if (upper->Is(Type::Boolean())) {
       // multiple uses => pick kRepBit.
       return kRepBit;
     } else if (upper->Is(Type::Number())) {
@@ skipping 139 matching lines @@
   bool CanLowerToUint32Binop(Node* node, MachineTypeUnion use) {
     return BothInputsAre(node, Type::Unsigned32()) &&
            (!CanObserveNonWord32(use) ||
             NodeProperties::GetType(node)->Is(Type::Unsigned32()));
   }
 
   bool CanObserveNonWord32(MachineTypeUnion use) {
     return (use & kTypeMask & ~(kTypeInt32 | kTypeUint32)) != 0;
   }
 
-  bool CanObserveMinusZero(MachineTypeUnion use) {
-    // TODO(turbofan): technically Uint32 cannot observe minus zero either.
-    return (use & (kTypeUint32 | kTypeNumber | kTypeAny)) != 0;
-  }
-
   bool CanObserveNaN(MachineTypeUnion use) {
     return (use & (kTypeNumber | kTypeAny)) != 0;
   }
 
   // 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()) {
       //------------------------------------------------------------------
@@ skipping 1170 matching lines @@
   ReplaceEffectUses(node, comparison);
   node->ReplaceInput(0, comparison);
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
   node->TrimInputCount(2);
   NodeProperties::ChangeOp(node, machine()->IntLessThanOrEqual());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8