[eder-matheus]

Summary

GSegment keeps a via's layer order, so FastRoute's partial-route builders (getPlanarRoute, get3DRoute and the bridging vias) added the same via twice when it was reached from both sides. For example, a sink pin's via stack is walked down to the pin and back up. getRoutes already skipped the reversed via; these paths did not. This PR adds addSegment, which finds a duplicate via in either layer order, and uses it for every segment the partial-route builders add.

Each duplicate became a parallel resistor in the mid-route parasitics that resistance-aware routing uses. OpenSTA's PRIMA maxParasiticPathResistance enumerates every simple path, so its runtime doubles with each duplicate on a path. This caused the asap7/swerv_wrapper GRT timeout in the ORFS nightly.

Type of Change

• Bug fix

Impact

• Partial-route parasitics are trees again. On asap7/swerv_wrapper (nightly 7675 4_cts.odb), parasitics estimated during the 3D maze pass went from 437,394 duplicate resistors on 86,549 of 87,431 nets (up to 203 per net) to none.
• The initial resistance-aware global_route on that design did not finish in 2.5 h without this fix and takes 72 s with it.
• Final routes are built by getRoutes, which this PR doesn't change.

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

ORFS nightly 7675: asap7/swerv_wrapper timed out in global route.

[gemini-code-assist]

Code Review

This pull request introduces a helper function addSegment in FastRoute.cpp to deduplicate routing segments and refactors several insertion blocks to use it. It also adds unit tests in TestMaze3D.cpp to verify that vias are added only once. The review feedback suggests optimizing addSegment to avoid unconditional copying of segments on the hot path, and replacing std::minmax with std::min and std::max in the test helper to prevent potential dangling references.