Use SAR for positive divident by a power-of two constant divisor.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 1359 matching lines @@
       Range* right_range = this->right()->definition()->range();
       return (right_range == NULL)
           || !right_range->IsWithin(0, RangeBoundary::kPlusInfinity);
     }
     default:
       return overflow_;
   }
 }
 
 
+bool BinarySmiOpInstr::RightIsPowerOfTwoConstant() const {
+  if (!right()->definition()->IsConstant()) return false;
+  const Object& constant = right()->definition()->AsConstant()->value();
+  if (!constant.IsSmi()) return false;
+  const intptr_t int_value = Smi::Cast(constant).Value();
+  if (int_value == 0) return false;
+  return Utils::IsPowerOfTwo(Utils::Abs(int_value));
+}
+
+
 RawAbstractType* BinaryMintOpInstr::CompileType() const {
   return Type::IntType();
 }
 
 
 intptr_t BinaryMintOpInstr::ResultCid() const {
   return kDynamicCid;
 }
 
 
@@ skipping 1450 matching lines @@
     default:
       UNREACHABLE();
   }
   return kPowRuntimeEntry;
 }
 
 
 #undef __
 
 }  // namespace dart