strm2oas: support LAYER <layername> TYPE OVERLAP ; for L-shaped abstracts

[stefanottili]

This is a feature request for the strm2oas --lefdef-macro-resolution-mode 0/1.
Rare use case, filed for completeness sake, not urgent.

When using strm2oas with --lefdef-macro-resolution-mode 0 or 1 one can create cells (struct) from the abstract (lef MACRO). In order to create L-shaped abstracts (or anything orthogonal for that matter) lef uses a layer defined as:

LAYER <layername> TYPE OVERLAP ;

The MACRO ... OBS(tructions) then define "cutout" area's, either RECT or POLYGON.
The shape of the MACRO outline is 'SIZE rectangle - OBS <overlap_layername>'

Currently strm2oas wrongfully warns about the OVERLAP layer TYPE OVERLAP not having a LEFOBS mapping.

Warning: No mapping for layer 'OVERLAP', purpose 'LEFOBS' - layer is ignored.

test_origin_hier.tgz

[stefanottili]

I've misunderstood the use of TYPE OVERLAP, it's not a "cutout", it defines the "valid area" of the MACRO.

So not SIZE - OVERLAP, it's either SIZE or if they exist OR(OBS OVERLAP).

Please find the fixed testcase attached.
test_origin_hier.tgz