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zachjs / sv2v

SystemVerilog to Verilog conversion
BSD 3-Clause "New" or "Revised" License
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Issue with $clog2 of a parameter #256

Closed flaviens closed 7 months ago

flaviens commented 8 months ago

Hi there! I'm trying to pass the EL2 core through Yosys. sv2v works without error, but yosys is then complaining about $clog2 of a parameter. It seems that the parameter disappears during sv2v, but I'm not very confident about that. I tried a slightly older sv2v version (10-29) and the newest, without it making any difference.

Here is a pickle ready to be consumed by sv2v. el2_pickle.zip

Generating RTLIL representation for module `$paramod$2bdb596ed0b0d0fd78c36713ac2804f44d511569\el2_lsu_dccm_mem'.
generated/sv2v_out.v:38018: ERROR: Failed to evaluate system function `\$clog2' with non-constant value.

Could you please have a quick look? I'm at your disposal, may you have any question. Thank you very much! Flavien

zachjs commented 8 months ago

I have an idea what's going on here, but I'll need some time. I intend to take a closer look this weekend.

zachjs commented 7 months ago

The $clog2 was actually unrelated. sv2v saw a pattern field name and thought it referred to a localparam defined further down due some extra indirection. This is closely related to #255. I've added logic to distinguish the typenames in struct patterns in a4639fa9ef21fdc8d1a04632a1698fbb5eecf9b3. Please let me know if it works for you. The converted output seems right to me, but I now believe you'll run into an unrelated Yosys limitation: YosysHQ/yosys#668.

This test case was very useful. Thank you very much for filing this issue!

flaviens commented 7 months ago

Hi Zach, thank you so much for your reactivity! This indeed seems to resolve the problem! :heart: As you mentioned, we run into https://github.com/YosysHQ/yosys/issues/668, although for this specific purpose, it is easier to adapt the source code syntax. Thanks!