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.
When we are iterating over a `SigSpec`, the visited values will be of
type `SigBit` (as is the return type of `operator*()`). Account for that
in the publicly declared types.
`std::iterator` has been deprecated in C++17. Yosys is being compiled
against the C++11 standard but plugins can opt to compile against a
newer one. To silence some deprecation warnings when those plugins are
being compiled, replace the `std::iterator` inheritance with the
equivalent type declarations.
* Keep the previous behavior when no tcl script is used
* Do not treat "-" as a flag but as a positional argument
* Keep including <unistd.h> as it's also used for other functions (at
least for the emscripten build)
* Move the custom getopt implementation into the Yosys namespace to
avoid potential collisions
The main speedup is accomplished by avoiding a heap allocation in the common case where the final string length is less than 128. Inlining stringf & vstringf adds an additional improvement.
The main speedup comes from swithing from using a SHA1 hash to std::hash<std::string>. There is no need to use an expensive cryptographic hash for fingerprinting in this context.
This PR speeds up by roughly 17% across a wide spectrum of designs
tested at Google. Particularly for the mux generation pass.
Co-authored-by: Rasmus Larsen <rmlarsen@google.com>
Signed-off-by: Ethan Mahintorabi <ethanmoon@google.com>
