Calling `throw dst_end_of_data_exception()` when the desired number of cycles has been reached means that the fst reader can't tidy up after itself and leads to memory leaks.
This doesn't happen when the `-stop` flag is used because the `Yosys::FstData` struct tracks the end time and skips the outer callback if the simulation has gone past the desired end time.
Move cycle checking into the inner callback along with the time checking means that the outer callback no longer needs to throw an exception in order to stop checking further values, while still allowing the fst reader to finish reading and deallocate memory.
libfst is no longer included in gtkwave and instead has its own repo. There has also been some refactoring, so the patches need to update to match, as does sim.cc.
Instead, change the default `Design::selected_modules()` to match the behaviour (i.e. `selected_unboxed_modules_warn()`) because it's a lot of files to touch and they don't really _need_ to be updated.
Also change `Design::selected_whole_modules()` users over to `Design::selected_unboxed_whole_modules()`, except `attrmap` because I'm not convinced it should be ignoring boxes. So instead, leave the deprecation warning for that one use and come back to the pass another time.
This allows tools like SBY to capture the $display output independent
from anything else sim might log. Additionally it provides source and
hierarchy locations for everything printed.
`memory_nordff` has the advantage that it can be called just ahead of
the simulation step no matter whether the clocked read port has been
inferred or was explicitly instantiated in a flow.
This adds the -noinitstate option which is required to simulate
counterexamples to induction with yw-cosim. Also add handling for
$initstate cells for non-co-simulation.
This makes clk2fflogic add an attr to $ff cells that carry the state of
the emulated async FF. The $ff output doesn't have any async updates
that happened in the current cycle, but the $ff input does, so the $ff
input corresponds to the async FF's output in the original design.
Hence this patch also makes the following changes to passes besides
clk2fflogic (but only for FFs with the clk2fflogic attr set):
* opt_clean treats the input as a register name (instead of the
output)
* rename -witness ensures that the input has a public name
* the formal backends (smt2, btor, aiger) will use the input's
name for the initial state of the FF in witness files
* when sim reads a yw witness that assigns an initial value to the
input signal, the state update is redirected to the output
This ensures that yosys witness files for clk2fflogic designs have
useful and stable public signal names. It also makes it possible to
simulate a clk2fflogic witness on the original design (with some
limitations when the original design is already using $ff cells).
It might seem like setting the output of a clk2fflogic FF to update the
input's initial value might not work in general, but it works fine for
these reasons:
* Witnesses for FFs are only present in the initial cycle, so we do
not care about any later cycles.
* The logic that clk2fflogic generates loops the output of the
genreated FF back to the input, with muxes in between to apply any
edge or level sensitive updates. So when there are no active updates
in the current gclk cycle, there is a combinational path from the
output back to the input.
* The logic clk2fflogic generates makes sure that an edge sensitive
update cannot be active in the first cycle (i.e. the past initial
value is assumed to be whatever it needs to be to avoid an edge).
* When a level sensitive update is active in the first gclk cycle, it
is actively driving the output for the whole gclk cycle, so ignoring
any witness initialization is the correct behavior.
Akash Levy
Neil Deo
Krystine Sherwin
Emil J. Tywoniak
Akash Levy
Miodrag Milanović
Alain Dargelas
Emily Schmidt
Jannis Harder
Dag Lem
Martin Povišer