We were performing the helper passes `abc9_ops -replace_zbufs` and
`abc9_ops -restore_zbufs` for every module, but those passes act on the
full design (and can't be applied entirely selectively due to entering
and leaving bufnorm).
This lead to an explosive creation of a lot of redundant bufnorm helper
cells that would have been cleaned up by `clean` but that never ran.
Instead we now run each helper pass once, one before and one after
iterating over the selected modules. This limits the number of bufnorm
helper cells.
This fixes some edge cases the previous version didn't handle properly
by simplifying the logic of determining directly driven wires and
representatives to use as buffer inputs.
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.
The `portarcs` pass was already ignoring `$buf` cells when loading
timing data, but now bufnorm will also emit `$input_port` and `$connect`
helper cells, which need to be ignored as well.
Was previously the number of proposed renames, but since renames can be skipped this causes the final count to differ from the number of actually renamed objects.
Check counts in `tests/various/autoname.ys`.
This option allows you to process a design that includes unsupported
SVA. Unsupported SVA gets imported as formal cells using 'x inputs and
with the `unsupported_sva` attribute set. This allows you to get a
complete list of defined properties or to check only a supported subset
of properties. To ensure no properties are unintentionally skipped for
actual verification, even in cases where `-sva-continue-on-error` is
used by default to read and inspect a design, `hierarchy -simcheck` and
`hierarchy -smtcheck` (run by SBY) now ensure that no `unsupported_sva`
property cells remain in the design.
