yosys-slang: SystemVerilog frontend for Yosys

yosys-slang is a Yosys plugin providing a new command (read_slang) for loading SystemVerilog designs.

yosys-slang builds on top of the slang library to provide comprehensive SystemVerilog support.

The plugin is available prebuilt as part of

• OSS CAD Suite from YosysHQ, and

• IIC-OSIC-TOOLS from Johannes Kepler University

Status

News: ETH Zürich has used yosys-slang for a chip tapeout. Meet MLEM.

News: The Microelectronics Design Center at ETH Zürich is now sponsoring yosys-slang development for usage in ASIC synthesis flows!

yosys-slang understands a synthesizable subset of SystemVerilog. Please open GitHub issues for missing features and/or confusing error messages.

yosys-slang can parse a number of open-source IPs, including:

• Black Parrot

• BSC Core Tile

• OpenHW Group's CV32E40P

• Ibex RISC-V Core

• OpenTitan: Open source silicon root of trust

• RSD RISC-V Out-of-Order Superscalar Processor

For details see the compat suite repository which documents sample command lines.

yosys-slang is on the CHIPS Alliance sv-tests dashboard where failing test cases and their error messages (with useful line numbers and AST dumps!) can be browsed. Note some tests on the sv-tests dashboard are misconfigured for testing a synthesis tool.

If you wish to sponsor the project's development, and prioritize certain features, please get in touch.

Building

Prerequisities:

• Yosys installed

• Usual toolchains, CMake

Check out the repository including the submodule, e.g. with

git clone --recursive https://github.com/povik/yosys-slang

Then build both slang and the build/slang.so plugin for Yosys:

make -j$(nproc)

Use a custom -jN switch to build with N concurrent processes instead of matching the number of cores.

The built plugin is placed at build/slang.so. Copy this file into the Yosys plugin directory, which can be achieved through make install, or use a full path to this file (instead of the slang shorthand) when loading the plugin.

Usage

You load the plugin into Yosys on startup by passing the -m argument:

$ yosys -m slang

Or, alternatively, you load the plugin at runtime with the plugin command:

plugin -i slang

After the plugin has been loaded, the frontend is invoked with the read_slang command.

For a full documentation of the command options, see help read_slang. The command understands standard slang options in addition to other options.

Sample usage:

read_slang picorv32.v --top picorv32 -D DEBUG

Contributing

Contributions are welcome! If you intent to develop a particular feature, feel free to get in touch and consult on the appropriate approach.

License

The main glue code (slang_frontend.cc slang_frontend.h memory.h addressing.h) is distributed under the ISC license, see LICENSE. The initial_eval.cc code contains modified portions of Slang and is distributed under the terms of the MIT license, see the file header.