Add two new options to the splitnets pass:
- `-ports_only`: Split only module ports, not internal signals. This is
useful when you want to split ports for interface compatibility while
keeping internal signals as multi-bit wires for better readability.
- `-top_only`: Apply splitting only at the top module level, not in
submodules. This is helpful for hierarchical designs where you need
split signals only at the top-level interface.
These options can be combined with existing flags:
- `splitnets -ports_only`: Split all ports in all modules
- `splitnets -ports_only -top_only`: Split ports only in top module
- `splitnets -ports -top_only`: Split both ports and nets only in top
Add comprehensive tests that verify wire/port counts for all flag
combinations using a hierarchical design.
I am getting weird crashes on `main` in `tests/sdc/alu_sub.ys` which I traced to a null `Wire*`
in `SdcObjects::constrained_ports`. The null `Wire*` is being set in the `SdcObjects`
constructor. I don't understand what's going on here, so I added this check to detect the
missing wire early ... and that made the crash go away. Compiler bug maybe? I have
`Debian clang version 19.1.7 (3+build5)`, default build configuration.
Anyway this code seems fine to have.
When IdString refcounting was expensive, it made sense to pass it by const reference
instead of by value, to avoid refcount churn. Now that IdString is not refcounted,
it's slightly more efficient to pass it by value.
Fixes these build errors I'm getting locally with `tcl-devel-9.0.0-7.fc42.x86_64`.
I guess Tcl 9 broke this.
```
passes/cmds/sdc/sdc.cc:438:6: error: no matching function for call to 'Tcl_ListObjLength'
438 | if (Tcl_ListObjLength(interp, listObj, &listLength) == TCL_OK) {
| ^~~~~~~~~~~~~~~~~
/usr/include/tclDecls.h:1788:13: note: candidate function not viable: no known conversion from 'int *' to 'Tcl_Size *' (aka 'long *') for 3rd argument
1788 | EXTERN int Tcl_ListObjLength(Tcl_Interp *interp,
| ^
1789 | Tcl_Obj *listPtr, Tcl_Size *lengthPtr);
| ~~~~~~~~~~~~~~~~~~~
passes/cmds/sdc/sdc.cc:446:8: error: no matching function for call to 'Tcl_ListObjLength'
446 | if (Tcl_ListObjLength(interp, subListObj, &subListLength) == TCL_OK) {
| ^~~~~~~~~~~~~~~~~
/usr/include/tclDecls.h:1788:13: note: candidate function not viable: no known conversion from 'int *' to 'Tcl_Size *' (aka 'long *') for 3rd argument
1788 | EXTERN int Tcl_ListObjLength(Tcl_Interp *interp,
| ^
1789 | Tcl_Obj *listPtr, Tcl_Size *lengthPtr);
| ~~~~~~~~~~~~~~~~~~~
```
This uses the environment variable `YOSYS_PLUGIN_PATH` to provide multiple colon-delimited search paths for native plugins in a similar manner to `PATH` for executables and `PYTHONPATH` for Python modules.
This addresses https://github.com/YosysHQ/yosys/issues/2545, allowing Yosys to be better packaged in non-FHS environments such as Nix.
