dpl: exclude macros from one_site_gap check

[gudeh]

Summary

Currently when we instantiate cells at Opendp::createNetwork() macros are considered Node::CELL, so cell->isStdCell() guarantees we don't attempt to check for one_site_gaps at macros. I understand it does not make sense to do so.

Macros are still considered for pixel painting.

Type of Change

• Bug fix

Impact

Excludes macros from checking one_site_gaps, and avoids a false positive error on a private design.

Verification

• I have verified that the local build succeeds (./etc/Build.sh).
• I have run the relevant tests and they pass.
• My code follows the repository's formatting guidelines.
• I have included tests to prevent regressions.
• I have signed my commits (DCO).

Related Issues

[gudeh]

Secure-CI ensures no-op.

[gemini-code-assist]

Code Review

This pull request updates the placement check logic in CheckPlacement.cpp to use cell->isStdCell() instead of checking cell->getType() == Node::CELL during the one-site gap check. I have no feedback to provide as there are no review comments.

[osamahammad21]

@gudeh I think this would work if you want to allow a one-site gap between two macros, but not between a macro and a standard cell. In that case, the check would traverse the standard-cell node and detect the one-site gap next to the macro. My question: is there a real design where you want to do that?

[gudeh]

We discussed this and I think it makes sense to dive a little deeper and understand why the bug happens anyway.