Add `src_attr` and `netlist_line` fields to `report_checks`

[akashlevy]

See title. src_attr is the src attribute of an instance in the netlist (useful for tracking an object back to source in pre-synthesis RTL). netlist_line is the line number for tracking an instance back to its source in the Verilog netlist.

Breakdown of work:

• [x] Update Sta, Network, ConcreteNetwork, and SdcNetwork to include line (line number of instantiation)
• [x] Update ReportPath to add the new fields to reporters
• [x] Update Search to add TCL interface to use the new fields
• [x] Add test to check that the new fields are reported correctly
• [x] Update docs to include new fields

Note that I updated the Sta API to support getting/setting line numbers on Instance/ConcreteInstance. I made specifying the line number optional by providing a default value, but anything implementing Network still needs to implement the line() function right now...

Let me know if you have any suggestions on the right strategy for annotating line numbers on instances.

[jjcherry56]

I understand why the src_attr is useful, but why is the netlist line interesting?

[akashlevy]

To be able to track where an instance is instantiated in the netlist without searching? Feels kind of useful to me, e.g., when you see an unexpected cell type on a critical path. But maybe not. Happy to upstream just src_attr if you prefer.

[QuantamHD]

How does this interact with the ( src = "file.v:245" ) attributes emitted by Yosys? Should we somehow leverage the existing infrastructure for that rather than add new fields?

[akashlevy]

@QuantamHD It is leveraging the existing infrastructure for src attribute parsing that you added. So not quite sure what you mean

[QuantamHD]

Ah, my bad @akashlevy. I didn't read it carefully enough

[akashlevy]

@jjcherry56 wanted to give this a bump. Any feedback?

[akashlevy]

Going to close this and re-open with just src_attr soon as discussed.