When IdString refcounting was expensive, it made sense to pass it by const reference
instead of by value, to avoid refcount churn. Now that IdString is not refcounted,
it's slightly more efficient to pass it by value.
Instead of checking for the presence of helper names each time we need to
determine whether to use association lists, explicitly store a boolean flag
indicating whether association list helpers are being used.
In order to support unsized constants being used as parameters, the `const` struct needs to know if it is unsized (so that the parameter can be used to set the size).
Add unsized flag to param value serialization and rtlil back-/front-end.
Add cell params to `tests/rtlil/everything.v`.
The aiger2 backend checks for unsupported cells during indexing. This
causes it to fail when `$connect` or `$tribuf` (as workaround for
missing 'z-$buf support) cells are present in the module.
Since bufnorm adds these cells automatically, it is very easy to end up
with them due to unconnected wires or e.g. `$specify` cells, which do
not pose an actual problem for the backend, since it will never
encounter those during a traversal.
With this, we ignore them during indexing and only produce an actual error
message if we reach such a cell during the traversal.
This makes the Verilog backend handle the $connect and $input_port
cells. This represents the undirected $connect cell using the `tran`
primitive, so we also extend the frontend to support this.
The $input_port cell is added by the bufnorm code to simplify handling
of input ports for new code that uses bufnorm, but the aiger2 backend
does already handle input ports separately, so we just ignore those.
With the previous bufnorm implementation inout ports were not supported
at all, so this didn't matter, but with the new bufnorm implementation
they need to be treated as output ports.
