========================================================================== Pragma Note: Hacks and Patches for Custom Pragma DSLs in Clang

A framework for providing rich, custom compiler hints to C programmers.

In technical terms, Pragma Note is a collection of hacks and patches that adds a pragma DSL authoring framework in the spirit of a simplified, generic version of OpenMP to Clang.

One might generously call it "a pretty nice kludge."

========================================================================== Getting Started

There's a patched copy of the LLVM + Clang source tree installed as a git subtree at llvm-tree/llvm. In order to write a custom DSL, we need to compile a patched Clang, and load our DSL as a plugin. It's recommended to build with ninja instead of make for noticeably faster compilation.

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Setting up and Compiling a Patched Clang + Note DSL Plugin

1. Compile the LLVM framework (this includes Clang, the Note DSL plugin, and the rest of the LLVM framework)

$ cd llvm
$ make 

2. Add what has been just compiled to your environment

$ source llvm/9.0.0/enable

3. In the root of the repository, check whether the plugin works:

$ automp -S -emit-llvm hello-note.c

You should see some debug output from the plugin in your terminal, and there should be a hello-note.ll file created that contains note.noelle metadata containing an anonymous struct of a single boolean true (1) value.