Reading the Symbiflow Installation guide you mention Mentor Graphics QuestaSim.
Will QuickLogic support any of the open source simulators Icarus Verilog or Cascade?
Or do you recommend any other free simulators for pre / post-layout simulation that your tools support?
Open Source Simulator
I just wanted to confirm that the SymbiFlow project already uses both Verilator (https://www.veripool.org/wiki/verilator) and Icarus Verilog (http://iverilog.icarus.com/) heavily and these tools should be documented as working once more verification has been done.