Allow both min / max version of a macro library for a given corner

[smunaut]

Description

When calling OpenSTA read_liberty you can use -min and -max arguments to load a different version of liberty timing information for the minimum path and maximum path.

Ideally you're want the ability to specify when declaring a macro so you can provide both a min and a max variant of timing info for each corner.

{
`nominal': {
   'min': [ 'macro_nominal_min_delay.lib' ] ,
   'max': ['macro_nominal_max_delay.lib']
 },
'slow': ...
}

So if the value for a corner is a list, then call read_liberty and if it's a dict then keys min / max are expected and read_liberty -min ... and read_liberty -max will be called.

The usefulness of that is that if you have combinatorial logic, liberty doesn't allow do describe a range of possible delay and for the top level setup / hold analysis to work it's important that the minimal possible delay is used for hold checks and the maximal possible delay is used for setup analysis.

Proposal

No response