[turbofan] Correctify representation changes to bit.

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/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 36 matching lines @@
       HeapObjectMatcher<HeapObject> m(node->InputAt(0));
       if (m.Is(Unique<HeapObject>::CreateImmovable(factory()->false_value()))) {
         return ReplaceInt32(0);
       }
       if (m.Is(Unique<HeapObject>::CreateImmovable(factory()->true_value()))) {
         return ReplaceInt32(1);
       }
       if (m.IsChangeBitToBool()) return Replace(m.node()->InputAt(0));
       break;
     }
+    case IrOpcode::kChangeWord32ToBit:
+      return ReduceChangeWord32ToBit(node);
     case IrOpcode::kChangeFloat64ToTagged: {
       Float64Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceNumber(m.Value());
       break;
     }
     case IrOpcode::kChangeInt32ToTagged: {
       Int32Matcher m(node->InputAt(0));
       if (m.HasValue()) return ReplaceNumber(m.Value());
       break;
     }
@@ skipping 62 matching lines @@
     Node* length = graph()->NewNode(simplified()->LoadField(access), input,
                                     graph()->start(), graph()->start());
     Node* compare = graph()->NewNode(simplified()->NumberEqual(), length,
                                      jsgraph()->ZeroConstant());
     return Change(node, simplified()->BooleanNot(), compare);
   }
   return NoChange();
 }
 
 
+Reduction SimplifiedOperatorReducer::ReduceChangeWord32ToBit(Node* node) {
+  Node* const input = NodeProperties::GetValueInput(node, 0);
+  Type* const input_type = NodeProperties::GetBounds(input).upper;
+  if (input_type->Is(jsgraph()->ZeroOneRangeType())) {
+    // ChangeWord32ToBit(x:bit) => x
+    return Replace(input);
+  }
+  return NoChange();
+}
+
+
 Reduction SimplifiedOperatorReducer::Change(Node* node, const Operator* op,
                                             Node* a) {
   DCHECK_EQ(node->InputCount(), OperatorProperties::GetTotalInputCount(op));
   DCHECK_LE(1, node->InputCount());
   node->set_op(op);
   node->ReplaceInput(0, a);
   return Changed(node);
 }
 
 
@@ skipping 30 matching lines @@
 }
 
 
 MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8