Handling complex VHDL semantics with an OO intermediate format

One of the most important problems for integrating CAD tools is the sharing of the design information between various tools and environments. Using a standard intermediate format makes the interfacing and processing very easy so that all the applications may start their own processing from intermediate formats. We have used the CHIRE (Compiled HDL Intermediate Representation with Extensibility) intermediate format, which is a revision of AIRE/CE and have implemented a VHDL analyzer that generates the CHIRE intermediate format and covers the whole grammar. It also has a powerful semantic checking capability. We propose a semantic checking algorithm and illustrate its steps by using a very complicated example for the challenging aspects of semantic checking in VHDL. Being a good example of using CHIRE, it also implicitly demonstrates the benefits of using an object-oriented format for CAD tools.