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.
This makes it possible for yosys commands to return values when invoked
as tcl commands. Right now no commands natively support this, but the
tee command can be used with json output like this:
```tcl
set stat [yosys tee -q -s result.json stat -json -top top]
dict get $stat modules \\top num_cells_by_type \$pmux
```
Or with newline separated lists like this:
```tcl
split [yosys tee -q -s result.string select -list top] "\n"
```
This pull request is to address YosysHQ/yosys#2980.
The documentation, as originally written, does not make it clear that yosys commands, when used within a tcl script, do not return any value to the tcl script.
This pull request notes this and offers a workaround via tee as noted in the issue.
POSIX defines $TMPDIR as containing the pathname of the directory where
programs can create temporary files. On most systems, this variable points to
"/tmp". However, on some systems it can point to a different location.
Without respecting this variable, yosys fails to run on such systems.
Signed-off-by: Mohamed A. Bamakhrama <mohamed@alumni.tum.de>
The only difference between "RTLIL" and "ILANG" is that the latter is
the text representation of the former, as opposed to the in-memory
graph representation. This distinction serves no purpose but confuses
people: it is not obvious that the ILANG backend writes RTLIL graphs.
Passes `write_ilang` and `read_ilang` are provided as aliases to
`write_rtlil` and `read_rtlil` for compatibility.
This includes the following significant changes:
* Patching ezsat and minisat to disable resource limiting code
on WASM/WASI, since the POSIX functions they use are unavailable.
* Adding a new definition, YOSYS_DISABLE_SPAWN, present if platform
does not support spawning subprocesses (i.e. Emscripten or WASI).
This definition hides the definition of `run_command()`.
* Adding a new Makefile flag, DISABLE_SPAWN, present in the same
condition. This flag disables all passes that require spawning
subprocesses for their function.
