Slingshot - SystemVerilog LSP

Slingshot is a language server for the SystemVerilog hardware description language, with a focus on accurate multi-file completion. The overarching goal is to make SystemVerilog as intuitive to edit as C++ or Python.

Compared to other SV LSPs, the main feature that Slingshot brings to the table is a powerful completion system, backed by ANTLR, that supports multi-file projects through automatic indexing. Slingshot also supports instant linting, backed by Verilator.

Slingshot is written in Kotlin and runs on a Java 17 JVM or higher.

Features

• Diagnostics (powered by Verilator)
  • Fully in-memory, does not write any temporary files to disk
• Completion (powered by ANTLR)
  • Context-sensitive completion based on cursor's position in the ANTLR parse tree
  • Slingshot is aware of both line and block comments, and does not suggest completions when you are inside a comment
  • Completion for "variables" (logic, wire, etc) and ports in the current module
  • Completion for language keywords, e.g. always_ff, always_comb, posedge
  • Snippets for various blocks, e.g. always_ff, always_comb, case, if
  • Completion for macros
• Cross-file completion
  • Slingshot can complete modules, enums and macros declared in other files
  • Every include path specified in the config file is searched and indexed automatically
• Simple configuration
  • Slingshot is configured through a simple .slingshot.yaml file declared in the project's root directory
  • This format is documented in docs/config.md

Future features are planned on the issue tracker.

Current state

Slingshot may be useful in moderately complicated SystemVerilog projects right now - feel free to give it a spin and report any issues you encounter! Previously, I thought I was close to a 1.0.0 release, however I've decided I would like to rewrite the completion system using slang, which I will need to implement as a gRPC server (or JNA binding, or likewise) and will thus need some extra effort. The trade-off I think is that the server quality will be much better than it currently is with ANTLR.

Timeline

Unfortunately, Slingshot is not being actively developed at this time due to my busy schedule with thesis, other uni subjects, and work. Originally, my thesis was going to be on processor design, and Slingshot was going to be a secondary deliverable. However, the thesis now concerns fault-tolerant EDA, so I'm not writing much (if any) SystemVerilog code.

Once my thesis is completed, I will probably return to Slingshot development more consistently, as I'm hoping to do my PhD on processor design, which will require SystemVerilog development.

Building and running

Building and environment

Important: Slingshot currently only runs on Linux and other *nix systems. Windows is not supported, and no support is currently planned (unless specifically requested).

You need Java 17 or higher.

The program can be built with ./gradlew build, which also generates JAR files in the build/libs directory.

Because the SystemVerilog generated parser is so massive, you will need to modify IntelliJ's max file parse size to be larger. Go to Help -> Edit Custom Properties and insert idea.max.intellisense.filesize=999999. Then, restart the IDE.

You also need to download and install Verilator using your system's package manager.

Running

Currently, I have only tested Slingshot in Neovim.

When Slingshot is a more capable LSP, it will (hopefully) be available in upstream LSP projects like mason.nvim and nvim-lspconfig.

Until then, you can manually add Slingshot as a nvim-lspconfig server by inserting the following into init.lua:

local lspconfig = require 'lspconfig'
local configs = require 'lspconfig.configs'

if not configs.slingshot then
  -- this require lspconfig.configs is the trick required to make it work
  require("lspconfig.configs").slingshot = {
    default_config = {
      cmd = {'java', '-jar', '<PATH_TO_SLINGSHOT>/slingshot/build/libs/slingshot-1.0-SNAPSHOT-all.jar'};
      filetypes = {'verilog', 'systemverilog'};
      root_dir = function(fname)
        return lspconfig.util.find_git_ancestor(fname) or vim.loop.os_homedir()
      end;
      settings = {};
    };
  }
end

lspconfig.slingshot.setup{}

This is the setup I use for development as well.

Important: Please read docs/config.md for instructions on how to create a .slingshot.yaml file to configure the server. This is mandatory for multi-file (read: most) projects.

Troubleshooting

Slingshot issues can be diagnosed by reading the log file. This is located in ~/.local/share/slingshot/slingshot.$PID.log, where $PID is the Slingshot process ID. You can just read the most recent log file. Currently, the 5 most recent log files are retained in that directory. The lnav tool is very useful for reading Slingshot log files.

If Verilator syntax checking is not working, please make sure Verilator is installed and is in your $PATH. The log file will also contain the exact cause of why the Verilator didn't work.

If there are errors about missing includes or not being able to find certain files, please make sure you have read docs/config.md and created your .slingshot.yaml file. Then, read the log to make sure that Slingshot has the correct root directory. The best way to ensure this is invoking Neovim by typing nvim . in the project's root directory - don't edit individual files.

If the above steps do not resolve your issue, please open a bug ticket in the GitHub issue tracker. You must include your log file, detailed description of the issue, and also a SystemVerilog code example if possible. As my time is extremely limited, I may not be able to respond to or fix bug tickets. Pull requests are welcome as well, but may take some time to review.

Design goals

See docs/design_goals.md

Implementation details

See docs/impl_details.md

Licence

Copyright (c) 2023, 2024 Matt Young. Available under the Mozilla Public License v2.0

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.