Hi, I'm a first time open source contributor looking to get involved and add something to XLS. After reading the XLS ideas page and going through issues such as this one, I decided to start by making an extension to the standard library to include more ML-relevant operations (which are becoming increasingly important in the hardware domain). This work has been overseen by @msaligane, who is a visiting faculty at Google.

I wanted to keep the pull requests fairly atomic, so I started with just two operations: ReLU (which is a pure fn) and a weight-stationary systolic array (which is a proc). I have more operations I am working on (e.g. approximated Softmax, output-stationary systolic array, etc) which I would be happy to contribute if reviewers are satisfied with this work, alongside appropriate documentation. I could pivot to a related idea in the standard library if the XLS team would prefer (e.g. a quantized floating point format).

I would like to note that the code for the systolic array here is different to the one provided in examples here. I found that my code got improved compilation times for the same architecture (details below). I am happy to gather PPA stats if it is deemed important.

The above times were averaged on 5 runs on a 16x16 systolic array.

I would sincerely appreciate all feedback, as I am trying to learn and would love to make this work.

P. S. I seem to have found a bug in the DSLX formatter wherein comments cannot be placed between multi-line arrays. There doesn't seem to be an open issue for this, so I may file one later.