verilator/verilator: Verilator open-source SystemVerilog simulator and lint system

Welcome to Verilator

Welcome to Verilator, the fastest Verilog/SystemVerilog simulator. Accepts Verilog or SystemVerilog

Performs lint code-quality checks

Compiles into multithreaded C++, or SystemC

Creates XML to front-end your own tools Fast Outperforms many closed-source commercial simulators

Single- and multithreaded output models Widely Used Wide industry and academic deployment

Out-of-the-box support from Arm and RISC-V vendor IP Community Driven & Openly Licensed Guided by the CHIPS Alliance and Linux Foundation

Open, and free as in both speech and beer

More simulation for your verification budget Commercial Support Available Commercial support contracts

Design support contracts

Enhancement contracts

What Verilator Does

Verilator is invoked with parameters similar to GCC or Synopsys's VCS. It "Verilates" the specified Verilog or SystemVerilog code by reading it, performing lint checks, and optionally inserting assertion checks and coverage-analysis points. It outputs single- or multithreaded .cpp and .h files, the "Verilated" code.

These Verilated C++/SystemC files are then compiled by a C++ compiler (gcc/clang/MSVC++), optionally along with a user's own C++/SystemC wrapper file, to instantiate the Verilated model. Executing the resulting executable performs the design simulation. Verilator also supports linking Verilated generated libraries, optionally encrypted, into other simulators.

Verilator may not be the best choice if you are expecting a full-featured replacement for a closed-source Verilog simulator, need SDF annotation, mixed-signal simulation, or are doing a quick class project (we recommend Icarus Verilog for classwork). However, if you are looking for a path to migrate SystemVerilog to C++/SystemC, or want high-speed simulation of designs, Verilator is the tool for you.

Performance

Verilator does not directly translate Verilog HDL to C++ or SystemC. Rather, Verilator compiles your code into a much faster optimized and optionally thread-partitioned model, which is in turn wrapped inside a C++/SystemC module. The results are a compiled Verilog model that executes even on a single thread over 10x faster than standalone SystemC, and on a single thread is about 100 times faster than interpreted Verilog simulators such as Icarus Verilog. Another 2-10x speedup might be gained from multithreading (yielding 200-1000x total over interpreted simulators).

Verilator has typically similar or better performance versus closed-source Verilog simulators (e.g., Carbon Design Systems Carbonator, Modelsim/Questa, Cadence Incisive/NC-Verilog, Synopsys VCS, VTOC, and Pragmatic CVer/CVC). But, Verilator is open-sourced, so you can spend on computes rather than licenses. Thus, Verilator gives you the best simulation cycles/dollar.

Installation & Documentation

For more information:

Support

Verilator is a community project, guided by the CHIPS Alliance under the Linux Foundation.

We appreciate and welcome your contributions in whatever form; please see Contributing to Verilator. Thanks to our Contributors and Sponsors.

Verilator also supports and encourages commercial support models and organizations; please see Verilator Commercial Support.

Related Projects

GTKwave - Waveform viewer for Verilator traces.

Icarus Verilog - Icarus is a full-featured interpreted Verilog simulator. If Verilator does not support your needs, perhaps Icarus may.

Open License

Verilator is free software; you can redistribute it and/or modify it under the terms of either the GNU Lesser General Public License Version 3 or the Perl Artistic License Version 2.0. See the documentation for more details.