[turbofan] Eliminate redundant masking operations for word8/word16 stores.

src/compiler/machine-operator.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/compiler/machine-type.h"
 
 namespace v8 {
@@ skipping 31 matching lines @@
   WriteBarrierKind write_barrier_kind_;
 };
 
 bool operator==(StoreRepresentation, StoreRepresentation);
 bool operator!=(StoreRepresentation, StoreRepresentation);
 
 size_t hash_value(StoreRepresentation);
 
 std::ostream& operator<<(std::ostream&, StoreRepresentation);
 
+StoreRepresentation const& StoreRepresentationOf(Operator const*);
+
 
 // Interface for building machine-level operators. These operators are
 // machine-level but machine-independent and thus define a language suitable
 // for generating code to run on architectures such as ia32, x64, arm, etc.
 class MachineOperatorBuilder FINAL {
  public:
   explicit MachineOperatorBuilder(MachineType word = kMachPtr);
 
   const Operator* Word32And();
   const Operator* Word32Or();
@@ skipping 116 matching lines @@
  private:
   const MachineOperatorBuilderImpl& impl_;
   const MachineType word_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_