This is an alternative to setting the dont_use property in lib. This brings
dfflibmap in parity with the abc pass for dont_use.
Signed-off-by: Austin Rovinski <rovinski@nyu.edu>
See the test case. PROC_ROM will consider this for evaluation, even
though -- without any actions -- lhs is empty (but still "uniform").
A zero-width memory is constructed, which later fails check with:
ERROR: Assert `width != 0' failed in kernel/mem.cc:518.
Ensure we don't proceed if there's nothing to encode.
Fixes a bug in the handling of the recently introduced $check cells.
Both $check and $print cells in clk2fflogic are handled by the same code
and the existing tests for that were only using $print cells. This
missed a bug where the additional A signal of $check cells that is not
present on $print cells was dropped due to a typo, rendering $check
cells non-functional.
Also updates the tests to explicitly cover both cell types such that
they would have detected the now fixed bug.
The purpose of memtest02 in tests/simple/memory.v is to test bit
select on both memory (mem1) and memory converted to registers (mem2).
After 7cfae2c52, mem1 was automatically converted to registers,
and the test no longer worked as intended. This is fixed by
adding (* nomem2reg *) to mem1.
This fixes hierarchy when used with cell libraries that were loaded with
-defer and also makes more of the hierarchy visible to the auto-top
heuristic.
Right now neither `sat` nor `sim` have support for the `$check` cell.
For formal verification it is a good idea to always run either
async2sync or clk2fflogic which will (in a future commit) lower `$check`
to `$assert`, etc.
While `sim` should eventually support `$check` directly, using
`async2sync` is ok for the current tests that use `sim`, so this commit
also runs `async2sync` before running sim on designs containing
assertions.
This compares the write_smt2 output pretty much verbatim, which contains
auto generated private names and fixes an arbitrary ordering. The tested
functionality is also covered by SBY tests which actually interpret the
write_smt2 output using an SMT solver and thus are much more robust, so
we can safely remove this test.
This is mostly useful for collecting coverage for the future `$check`
cell, where, depending on the flavor, formatting a message may not be
wanted even for a failed assertion.
The behavior of these format specifiers is highly specific to Verilog
(`$time` and `$realtime` are only defined relative to `$timescale`)
and may not fit other languages well, if at all. If they choose to use
it, it is now clear what they are opting into.
This commit also simplifies the CXXRTL code generation for these format
specifiers.
This commit achieves three roughly equally important goals:
1. To bring the rendering code in kernel/fmt.cc and in cxxrtl.h as close
together as possible, with an ideal of only having the bigint library
as the difference between the render functions.
2. To make the treatment of `$time` and `$realtime` in CXXRTL closer to
the Verilog semantics, at least in the formatting code.
3. To change the code generator so that all of the `$print`-to-`string`
conversion code is contained inside of a closure.
There are two reasons to aim for goal (3):
a. Because output redirection through definition of a global ostream
object is neither convenient nor useful for environments where
the output is consumed by other code rather than being printed on
a terminal.
b. Because it may be desirable to, in some cases, ignore the `$print`
cells that are present in the netlist based on a runtime decision.
This is doubly true for an upcoming `$check` cell implementing
assertions, since failing a `$check` would by default cause a crash.
This makes tests/verilog/dynamic_range_lhs.v pass, after ensuring that
nowrshmsk is actually tested.
Stride is extracted from indexing of two-dimensional packed arrays and
variable slices on the form dst[i*stride +: width] = src, and is used
to optimize the generated CASE block.
Also uses less confusing variable names for indexing of lhs wires.
The previous version could easily generate a large amount of padding
when the constant factor was significantly larger than the width of the
shift data input. This could lead to huge amounts of logic being
generated before then being optimized away at a huge performance and
memory cost.
Additionally and more critically, when the input width was not a
multiple of the constant factor, the input data was padded with 'x bits
to such a multiple before interspersing the 'x padding needed to align
the selectable windows to power-of-two offsets.
Such a final padding would not be correct for shifts besides $shiftx,
and the previous version did attempt to remove that final padding at the
end so that the native zero/sign/x-extension behavior of the shift cell
would be used, but since the last selectable window also got
power-of-two padding appended after the padding the code is trying to
remove got added, it did not actually fully remove it in some cases.
I changed the code to only add 'x padding between selectable windows,
leaving the last selectable window unpadded. This omits the need to add
final padding to a multiple of the constant factor in the first place.
In turn, that means the only 'x bits added are actually impossible to
select. As a side effect no padding is added when the constant factor is
equal to or larger than the width of the shift data input, also solving
the reported performance bug.
This fixes#4056
Miodrag Milanović
Austin Rovinski
Martin Povišer
N. Engelhardt
Amelia Cuss
Jannis Harder
Dag Lem
Thomas Watson
Catherine
Merry
Krystine Sherwin