[turbofan] Avoid useless bit masking in typed lowering.

src/compiler/js-typed-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/access-builder.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-builtin-reducer.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/node-aux-data-inl.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 18 matching lines @@
 }
 
 
 JSTypedLowering::JSTypedLowering(JSGraph* jsgraph)
     : jsgraph_(jsgraph), simplified_(jsgraph->zone()) {
   Factory* factory = zone()->isolate()->factory();
   Handle<Object> zero = factory->NewNumber(0.0);
   Handle<Object> one = factory->NewNumber(1.0);
   zero_range_ = Type::Range(zero, zero, zone());
   one_range_ = Type::Range(one, one, zone());
+  Handle<Object> thirtyone = factory->NewNumber(31.0);
+  zero_thirtyone_range_ = Type::Range(zero, thirtyone, zone());
 }
 
 
 JSTypedLowering::~JSTypedLowering() {}
 
 
 Reduction JSTypedLowering::ReplaceEagerly(Node* old, Node* node) {
   NodeProperties::ReplaceWithValue(old, node, node);
   return Changed(node);
 }
@@ skipping 23 matching lines @@
 
   void ConvertInputsToString() {
     node_->ReplaceInput(0, ConvertToString(left()));
     node_->ReplaceInput(1, ConvertToString(right()));
   }
 
   // Convert inputs for bitwise shift operation (ES5 spec 11.7).
   void ConvertInputsForShift(bool left_signed) {
     node_->ReplaceInput(0, ConvertToI32(left_signed, left()));
     Node* rnum = ConvertToI32(false, right());
-    node_->ReplaceInput(1, graph()->NewNode(machine()->Word32And(), rnum,
-                                            jsgraph()->Int32Constant(0x1F)));
+    Type* rnum_type = NodeProperties::GetBounds(rnum).upper;
+    if (!rnum_type->Is(lowering_->zero_thirtyone_range_)) {
+      rnum = graph()->NewNode(machine()->Word32And(), rnum,
+                              jsgraph()->Int32Constant(0x1F));
+    }
+    node_->ReplaceInput(1, rnum);
   }
 
   void SwapInputs() {
     Node* l = left();
     Node* r = right();
     node_->ReplaceInput(0, r);
     node_->ReplaceInput(1, l);
     std::swap(left_type_, right_type_);
   }
 
@@ skipping 700 matching lines @@
       return JSBuiltinReducer(jsgraph()).Reduce(node);
     default:
       break;
   }
   return NoChange();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8