[stubs] Suppress shifts with immediate shift of zero.

src/compiler/code-assembler.cc

 // Copyright 2015 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/code-assembler.h"
 
 #include <ostream>
 
 #include "src/code-factory.h"
 #include "src/compiler/graph.h"
@@ skipping 191 matching lines @@
 }
 
 #define DEFINE_CODE_ASSEMBLER_BINARY_OP(name)   \
   Node* CodeAssembler::name(Node* a, Node* b) { \
     return raw_assembler_->name(a, b);          \
   }
 CODE_ASSEMBLER_BINARY_OP_LIST(DEFINE_CODE_ASSEMBLER_BINARY_OP)
 #undef DEFINE_CODE_ASSEMBLER_BINARY_OP
 
 Node* CodeAssembler::WordShl(Node* value, int shift) {
-  return raw_assembler_->WordShl(value, IntPtrConstant(shift));
+  return (shift != 0) ? raw_assembler_->WordShl(value, IntPtrConstant(shift))
+                      : value;
 }
 
 Node* CodeAssembler::WordShr(Node* value, int shift) {
-  return raw_assembler_->WordShr(value, IntPtrConstant(shift));
+  return (shift != 0) ? raw_assembler_->WordShr(value, IntPtrConstant(shift))
+                      : value;
+}
+
+Node* CodeAssembler::Word32Shr(Node* value, int shift) {
+  return (shift != 0) ? raw_assembler_->Word32Shr(value, IntPtrConstant(shift))
+                      : value;
 }
 
 Node* CodeAssembler::ChangeUint32ToWord(Node* value) {
   if (raw_assembler_->machine()->Is64()) {
     value = raw_assembler_->ChangeUint32ToUint64(value);
   }
   return value;
 }
 
 Node* CodeAssembler::ChangeInt32ToIntPtr(Node* value) {
@@ skipping 671 matching lines @@
       }
     }
   }
 
   bound_ = true;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8