llvm-dialects

Overview

The LLVM Dialects library allows defining "dialects" on top of the LLVM IR "substrate" in a TableGen-based DSL that looks, on purpose, very much like the DSL used to define MLIR dialects.

Its main user is LLPC. We welcome other interested parties. Development of llvm-dialects happens on GitHub, using Issues and Pull Requests.

LLVM Compatibility

The dev branch is generally expected to work with (a recent version of) the main branch of the llvm-project repository. No promises are made about compatibility with any specific LLVM version.

Components

• lib/Dialect: a helper library that allows the creation of basic dialects (in the MLIR sense) for LLVM IR
• lib/TableGen: common code for interpreting TableGen records that define a dialect
• utils/llvm-dialects-tblgen: a standalone CLI tool which reads a .td dialect definition and outputs C++ header and source files

Building

The are multiple ways to combine llvm and llvm-dialects into a build process. Common options are:

• Build llvm-dialects stand-alone against an installed llvm.
• Build both llvm-dialects and llvm as part of some larger build process, e.g. with both being submodules of the enclosing project.
• Build llvm-dialects as part of an llvm build. After checking out llvm-dialects in llvm/tools and re-running CMake, the llvm_dialects target (and other llvm-dialects targets) is available.

Testing

Run the check-llvm-dialects target to run a suite of automated tests. Run the check-llvm-dialects-lit target to run only the lit tests, and the check-llvm-dialects-units to run only the unit tests.