Slight difference in results when using -corners

[maliberty]

Discussed in #6174

^{Originally posted by kareefardi November 17, 2024}
test.tar.gz
This is a test case of two scripts running global placement. Both functionally should be identical. The difference is one uses -corner for set_wire_rc while the other doesn't.

For the case using -corner, set_layer_rc is needed. The code attempts to fetch the default values in the tlef and reuse them in set_layer_rc after doing the necessary unit conversions.

There seems to be a slight difference in the output generated from both runs (notice the reported slacks and HPWL) and I am wondering if this a round-off error, a methodology error at my end or something else related to OR itself.