What recently changed with dummy clock loads?

[donn]

As of recent versions of OpenROAD, CTS creates a number of dummy load cells. At least until d423155, these cells weren't being created. The problem isn't with the cells per se, rather, that as dummy loads, they have no outputs. We run a sanity checker ensuring that all cells and macros have at least one output connected.

We can start ignoring cells starting with clkload, but I guess my question I guess would be: why is this showing up now? (Also, would it be possible to change the prefix to something less generic?)

repro.tgz

Just ./run.sh.

Git commit: 6db1982e4628e0065373cf403860daae1dfa8c04
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cmake version 3.27.7

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[maliberty]

This is a recent enhancement. The dummy loads help to balance the clock tree and reduce skew. They are intentionally dangling. We could put a DEF property on the instance if that is helpful.

[donn]

Would be very helpful, yeah, assuming said property is accessible using the odb API of course