Both parameters and attributes are necessary because the parameters
have to be the same between every instantiation of the cell, but
attributes may well vary. For example, for an UART PHY, the type
of the PHY (tty, pty, socket) would be a parameter, but configuration
of the implementation specified by the type (socket address) would
be an attribute.
This commit adds support for replacing RTLIL modules with CXXRTL
black boxes. Black box port widths may not depend on the parameters
with which it is instantiated (yet); the parameters may only be used
to change the behavior of the black box.
The $paramod name mangling is not invertible (the \ character, which
separates the module name from the parameters, is valid in the module
name itself), which does not stop people from trying to invert it.
This commit makes it easy to invert the name mangling by storing
the original name explicitly, and fixes the firrtl backend to use
the newly introduced attribute.
There is no practical benefit from using `const memory` for ROMs;
it uses an std::vector internally, which prevents contemporary
compilers from constant-propagating ROM contents. (It is not clear
whether they are permitted to do so.)
However, there is a major benefit from using non-const `memory` for
ROMs, which is the ability to dynamically fill the ROM for each
individual simulation.
This commit makes it possible to use several cxxrtl-generated files
in one application, as well as compiling cxxrtl-generated code as
a separate compilation unit.
Also, fix the semantics of SET/CLR inputs of the $dffsr cell, and
fix the scheduling of async FF cells to consider ARST/SET/CLR->Q
as a forward combinatorial arc.
This commit reduces space and time overhead for writable memories
to O(write port count) in both cases; implements handling for write
port priorities; and simplifies runtime representation of memories.
Hierarchical design simulations are generally much slower, but this
comes with a major increase in flexibility:
1. Since the `flatten` pass currently does not support flattening
of designs with processes, this is the only way to simulate such
designs with cxxrtl.
2. Support for hierarchy paves way for simulation black boxes,
which are necessary for e.g. replacing PHYs with C++ code that
integrates with the host system.
After this commit, if NDEBUG is not defined, out-of-bounds accesses
cause assertion failures for reads and writes. If NDEBUG is defined,
out-of-bounds reads return zeroes, and out-of-bounds writes are
ignored.
This commit also adds support for memories that start with a non-zero
index (`Memory::start_offset` in RTLIL).
This results in further massive gains in performance, modest decrease
in compile time, and, for designs without feedback arcs, makes it
possible to run eval() once per clock edge in certain conditions.
In the past I was calling the ILANG_BACKEND::dump_const() to dump
values to an output stream. When these values were strings, the
function used to add quotes around them. The firrtl compiler, in turn,
escaped these quotes and the result was double-quoted strings which
were hard to read.
However I'm now calling design_entity->get_src_attribute() directly
and there is no additional quote being put around it, so we can
safely remove the unnecessary call to str.erase() here.
Yosys puts quotes around the string that represents the fileinfo whereas
firrtl does not. So when firrtl sees quotes, it escapes them with an extra
backslash which makes it hard to read afterwards.
Modifies smt2 backend to recognize `$anyconst` etc. assigned to a wire with the `maximize` or `minimize` attribute and emit `; yosys-smt2-maximize` or `; yosys-smt2-minimize` directives as appropriate.
Modifies `backends/smt2/smtbmc.py` and `smtio.py` to recognize those directives and emit a `(maximize ...)` or `(minimize ...)` command at the end of `smt_forall_assert()`, as described in the paper "νZ - An Optimizing SMT Solver" by Nikolaj Bjørner et al.
Adds an example `examples/smtbmc/demo9.v` to show how it can be used.
This increases compatibility with certain older parsers in some cases
that worked before commit 15fae357 but do not work with the current
compat-int mode
Before, the rules for encoding parameters in JSON were as follows:
- if the parameter is not a string:
- if it is exactly 32 bits long and there are no z or x bits, emit it
as an int
- otherwise, emit it as a string made of 0/1/x/z characters
- if the parameter is a string:
- if it contains only 0/1/x/z characters, append a space at the end
to distinguish it from a non-string
- otherwise, emit it directly
However, this caused a problem in the json11 parser used in nextpnr:
yosys emits unsigned ints, and nextpnr parses them as signed, using
the value of INT_MIN for values that overflow the signed int range.
This caused destruction of LUT5 initialization values. Since both
nextpnr and yosys parser can also accept 32-bit parameters in the
same encoding as other widths, let's just remove that special case.
The old behavior is still left behind a `-compat-int` flag, in case
someone relies on it.
Claire Wolf
whitequark
Claire Wolf
N. Engelhardt
Marcelina Kościelnicka
David Shah
Eddie Hung
Miodrag Milanovic
Sahand Kashani
Alberto Gonzalez
Teguh Hofstee
R. Ou