Create unit-test for Mul.sv eqy

[oharboe]

Description

An attempt at creating a test was started here, but a unit-test seems more approperiate.

A eqy unit-test can span synthesis and ORFS .tcl scripts, so it seems approperiate to have unit-tests with eqy in ORFS rather than in OpenROAD.

Tasks:

• How can Mul.sv in [DO NOT REVIEW] asap7/mul: equivalence check #2300 be best expressed as a fast eqy unit-test in ORFS and how are all steps covered? In particular it would be useful to have some unit-tests that start with checking synthesis.
• . env.sh and make DESIGN_CONFIG=designs/asap7/mul/config.mk in [DO NOT REVIEW] asap7/mul: equivalence check #2300 fails locally because eqy is not in the path, even though it is in dependencies/bin/eqy
• Hook up this test to CI
• Investigate the eqy failure that we're trying to study here, seems like this is a known problem in Yosys. LEC failed after yosys synthesis YosysHQ/yosys#3879 extract_fa: Fix handling inversion of an FA xor output YosysHQ/yosys#3882
• This is an attempt to rearticulate this test-case in ORFS speak: eqy: Add eqy_test rule for equivalence checking and test bazel-orfs#119

Suggested Solution

Not sure about the best way to test this in ORFS.

Additional Context

No response

[oharboe]

@maliberty Per discussion, I think this is possibly a very obtuse one-off bug in Yosys, never seen anything like it, so it does not seem worth it to add a generic yosys eqy testing capability in ORFS.