message: Add a convenient getDialect() accessor on Op<> class
diff: @@ -769,6 +769,9 @@ public:
  /// Return the operation that this refers to.
  Operation *getOperation() { return OpState::getOperation(); }
  + /// Return the dialect that this refers to.
  + Dialect *getDialect() { return getOperation()->getDialect(); }
  +
  /// Return the Region enclosing this Op.
  Region *getContainingRegion() { return getOperation()->getParentRegion(); }
  