[turbofan] Improve code generation for inline comparisons with zero.

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 438 matching lines @@
         VisitInputs(node);
         return SetOutput(node, kRepTagged);
 
       //------------------------------------------------------------------
       // Simplified operators.
       //------------------------------------------------------------------
       case IrOpcode::kBooleanNot: {
         if (lower()) {
           MachineTypeUnion input = GetInfo(node->InputAt(0))->output;
           if (input & kRepBit) {
-            // BooleanNot(x: kRepBit) => WordEqual(x, #0)
-            node->set_op(lowering->machine()->WordEqual());
+            // BooleanNot(x: kRepBit) => Word32Equal(x, #0)
+            node->set_op(lowering->machine()->Word32Equal());
             node->AppendInput(jsgraph_->zone(), jsgraph_->Int32Constant(0));
           } else {
             // BooleanNot(x: kRepTagged) => WordEqual(x, #false)
             node->set_op(lowering->machine()->WordEqual());
             node->AppendInput(jsgraph_->zone(), jsgraph_->FalseConstant());
           }
         } else {
           // No input representation requirement; adapt during lowering.
           ProcessInput(node, 0, kTypeBool);
           SetOutput(node, kRepBit);
@@ skipping 697 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