Pass Pipeline

Purpose

Pass Pipeline is a python library for generating pipeline json descriptors for Swift. The goal is to enable a user to generate various pass pipelines without needing to recompile the compiler. The main targets for this work are:

1. Correctness issues exposed by adding and removing parts of pass pipelines.
2. Exploration of various pipelines from a performance perspective.

Why not just use sil-opt and generate IR from sil for this purpose?

This is necessary since currently we do not have the infrastructure to always be able to use sil-opt and friends to generate IR from a .sil file. This is a shortcut around such issues.

The JSON Descriptor Format

The general format is as follows:

[ [ "PASS_MANAGER_ID", "run_n_times"|"run_to_fixed_point", count, "PASS1", "PASS2", ... ], ... ]

Where "id" is printed out when we process the action, "action" can be one of "run_n_times", "run_to_fixed_point" and "passes" is a list of passes to run. The names to use are the stringified versions of pass kinds.

Structure

There are two parts to this library. In src, we have the library building blocks. This is where we define the passes and the general pipeline infrastructure. In scripts, is where we implement various pipeline generators using code from src.