This tutorial will walk you through the creation of a simple transformation pass for Dynamatic that simplifies merge-like operations in Handshake-level IR. We'll look at the process of declaring a pass in TableGen format, creating a header file for the pass that includes the auto-generated pass declaration code, and implementing the transformation as part of an mlir::OperationPass. Then, we'll look at how to use a greedy pattern rewriter to make our pass easier to write and able to optimize the IR in more situations.
This tutorial assumes basic knowledge of C++, MLIR, and of the theory behind dataflow circuits. For a basic introduction to MLIR and its related jargon, see the MLIR primer. The full (runnable!) source code for this tutorial is located in tutorials/include/tutorials/CreatingPasses (headers) as well as in tutorials/lib/CreatingPasses (sources), and is built alongside the rest of the project by default.
This tutorial is divided in the following chapters:
- Chapter #1 | Description of what we want to achieve with the transformation pass: simlifying merge-like operations in the IR.
- Chapter #2 | Writing an initial version of the pass that transforms the IR in (almost!) the intended way.
- Chapter #3 | Improving the pass design and fixing our previous issue using a
GreedyPatternRewriterDriver.