The XLS (Accelerated HW Synthesis) project aims to enable the rapid development of hardware IP that also runs as efficient host software via “software style” methodology.
XLS implements a High Level Synthesis (HLS) toolchain which produces synthesizable designs from flexible, high-level descriptions of functionality. It is fully Open Source: Apache 2 licensed and developed via GitHub.
XLS is used inside of Google for generating feed-forward pipelines from “building block” routines / libraries that can be easily retargeted, reused, and composed in a latency-insensitive manner.
Not yet available, but active work in progress is the implementation of XLS concurrent processes, in Communicating Sequential Processes (CSP) style, that allow pipelines to communicate with each other and induct over time.
XLS is still experimental, undergoing rapid development, and not an officially supported Google product. Expect bugs and sharp edges. Please help by trying it out, reporting bugs, and letting us know what you think!
Building From Source
Currently, XLS must be built from source using the Bazel build system.
Note: Binary distributions of the XLS library are not currently available, but we hope to enable them via continuous integration, see this issue.
The following instructions are for the Ubuntu 20.04 (Focal) Linux distribution. Note that we start by assuming Bazel has been installed.
# Follow the bazel install instructions:
# Afterwards we observe:
$ bazel --version
$ sudo apt install python3-dev python3-distutils python3-dev libtinfo5
# py_binary currently assume they can refer to /usr/bin/env python
# even though Ubuntu 20.04 has no `python`, only `python3`.
# See https://github.com/bazelbuild/bazel/issues/8685
$ mkdir -p $HOME/opt/bin/
$ ln -s $(which python3) $HOME/opt/bin/python
$ echo 'export PATH=$HOME/opt/bin:$PATH' >> ~/.bashrc
$ source ~/.bashrc
$ bazel test -c opt ...
A reference build/test environment setup is also provided via Dockerfile:
~$ git clone https://github.com/google/xls.git
~$ cd xls
~/xls$ docker build . # Performs optimized build and test.
Stack Diagram and Project Layout
Navigating a new code base can be daunting; the following description provides a high-level view of the important directories and their intended organization / purpose, and correspond to the components in this XLS stack diagram:
Discussions about XLS – development, debugging, usage, and anything else – should go to the xls-dev mailing list.