Add icarus-verilog to test suite.

[cgyurgyik]

I think it would be a good idea to add a few tests (one specifically for sqrt) for the icarus-verilog backend. Perhaps benchmarks as well? This would require some additions to the Github Actions.

[cgyurgyik]

The other option would be to run all the tests through both verilog and icarus-verilog.

[rachitnigam]

I think it'd be better to make icarus-verilog tests run in the integration test suite? In general, icarus is faster than Verilator so at some point, it'd make sense to switch the default test suite to icarus. However, let's do that once we're convinced that Calyx programs obey icarus semantics.

[cgyurgyik]

The parallel example I was imagining is running C++ tests with multiple compilers (Clang, MSVC, ...) since compilation on one does not guarantee compilation on the other.

[rachitnigam]

The parallel example I was imagining is running C++ tests with multiple compilers (Clang, MSVC, ...) since compilation on one does not guarantee compilation on the other.

Where did you talk about parallel examples?

[cgyurgyik]

The other option would be to run all the tests through both verilog and icarus-verilog.

I'm providing insight on why I mentioned this.

[rachitnigam]

Hm, I think it's better to prioritize making Calyx programs work with multiple simulators instead of multiple C++ compilers. In some sense, if the latter doesn't work, it's compilers disagreeing on the semantics of C++; if the former doesn't work, it's simulators disagreeing on the semantics of Calyx.

[cgyurgyik]

Yes That's what I mean. The test suite should run through both verilog and iverilog, instead of one or the other.

[rachitnigam]

Given that we have started recommending Icarus verilog in our getting started document, this is even more necessary now.