GHDL is the leading VHSIC Hardware Description Language (VHDL) simulator.

Digital and mixed-signal systems such as field-programmable gate arrays
and integrated circuits can be described by VHDL, and VHDL  can also be
used as a general purpose parallel programming language.  GHDL compiles
VHDL files and creates a binary which simulates the design.

GHDL fully supports IEEE 1076-1987, IEEE 1-76-1993, IEEE 1076-2002
versions of VHDL, and partially IEEE 1076-2008.

WWW: https://github.com/ghdl/ghdl