Using SSAS for retrieval data instead of using SSRS to make a report? If you work with Reporting service in order to create a report and you need to retrieve data from the relational database.

The datamodel of the relational database can be structured in a certain way that can be very difficult to retrieve right data by using join and lots of SQL. In order to save time and cost, it is recommended to use analysis service to retrieve right data that takes less time and cost and the result of the analysis service can be used in reporting service? 

In other words, is it recommended to retrieve data in SSAS that will sent to SSRS instead of using SSRS to do lots of SQL coding in order to display right data in the report?

// Fullmetalboy
Depending on what type/volume of data you are reporting on, SSAS can possibly make it easier. I would not take that as a blanket statement. The decision to generate reports off of a relational or dimensional database should be made on a case by case basis.

Keep in mind that the development required to build an OLAP database around a subject area is far more time consuming than building a single report (or even several). 

The benefits of building out an OLAP database are huge in return. In many cases, your users can connect directly to it with excel and generate their own reports. This eases the SSRS development requirements on IT.

At the end of the day, there are many factors that would contribute to answering your question. There is simply not a one size fits all solution.