The `has_srst`` case was checking `sig_ce` instead of `sig_srst` due to
a copy and paste error.
This would crash when `has_ce` was false and could incorrectly determine
that an initial value is unused when `has_ce` and `has_srst` are both
set.
Find FFs with undefined initialization values for which changing the
initialization does not change the observable behavior and initialize
them. For -ff2anyinit, this reduces the number of generated $anyinit
cells that drive wires with private names.
This attribute can be used by formal backends to indicate which clocks
were mapped to the global clock. Update the btor and smt2 backend which
already handle clock inputs to understand this attribute.
These can be used to protect undefined flip-flop initialization values
from optimizations that are not sound for formal verification and can
help mapping all solver-provided values in witness traces for flows that
use different backends simultaneously.
Emil J. Tywoniak
Jannis Harder