Reduce strength of ModI for power-of-2 divisor.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 6c516f2497e01ae6e63a9cca6f241d55d2929172..2178184404eddca42bffc22bfc39c7ec46f25c08 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -2567,6 +2567,16 @@ class HMod: public HArithmeticBinaryOperation {
     SetFlag(kCanBeDivByZero);
   }
 
+  bool HasPowerOf2Divisor() {
+    if (right()->IsConstant() &&
+        HConstant::cast(right())->HasInteger32Value()) {
+      int32_t value = HConstant::cast(right())->Integer32Value();
+      return value != 0 && (IsPowerOf2(value) || IsPowerOf2(-value));
+    }
+
+    return false;
+  }
+
   virtual HValue* EnsureAndPropagateNotMinusZero(BitVector* visited);
 
   DECLARE_CONCRETE_INSTRUCTION(Mod, "mod")