odb: verify bump pin geometry against region's declared contact layer

[osamahammad21]

Summary

• 3DBlox linter: verify each bump's pin geometry lands on its region's declared contact layer (dbChipRegion::getLayer())
• New Checker::checkBumpLayer() flags mismatches with a marker per bump (category "Bump layer mismatch") plus a summary warning; regions with no declared layer are left unverifiable and not flagged
• Bump masters are also now required to expose exactly one pin, matching the assumption downstream code already makes; violations warn once per master from the bump map ingestion path (ThreeDBlox::warnIfMultiPinBumpMaster)

Type of Change

• New feature

Impact

• check_3dblox output can now include a "Bump layer mismatch" marker category for bumps whose master pin geometry doesn't touch their region's declared contact layer, and a one-time warning for multi-pin bump masters
• No behavior change for regions that don't declare a contact layer, or for existing checks/flows

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

None

[gemini-code-assist]

Code Review

This pull request introduces a validation check to ensure that bump cells expose exactly one pin, warning if a multi-pin bump master is encountered. It also adds a checker to verify that a bump's pin geometry lands on its region's declared contact layer, along with corresponding unit tests. The review feedback highlights several critical areas where missing null pointer checks on instances and masters could lead to application crashes, recommending defensive checks before dereferencing these pointers.

[gemini-code-assist]

If a bump does not have a valid instance or master (e.g., due to database inconsistency or deletion), calling bump->getInst()->getMaster() will result in a null pointer dereference and crash. We should defensively check if the instance and master are valid before calling masterPinOnLayer.

      for (dbChipBump* bump : region->getChipBumps()) {
        dbInst* inst = bump->getInst();
        if (inst && inst->getMaster()) {
          bump_layer_match_[bump]
              = masterPinOnLayer(inst->getMaster(), layer);
        }
      }

[osamahammad21]

defensive

[gemini-code-assist]

If chip_bump->getInst() is null, calling chip_bump->getInst()->getName() will cause a null pointer dereference and crash. We should check if the instance is valid before proceeding and using its name.

  for (dbUnfoldedChipBumpInst* bump : db_->getUnfoldedChipBumpInsts()) {
    dbChipBump* chip_bump = bump->getChipBumpInst()->getChipBump();
    const auto it = bump_layer_match_.find(chip_bump);
    if (it == bump_layer_match_.end() || it->second) {
      continue;
    }
    dbInst* inst = chip_bump->getInst();
    if (!inst) {
      continue;
    }
    violation_count++;
    if (!cat) {
      cat = dbMarkerCategory::createOrReplace(top_cat, "Bump layer mismatch");
    }
    if (auto* marker = dbMarker::create(cat)) {
      const Point3D p = bump->getGlobalPosition();
      marker->addSource(bump->getChipBumpInst());
      marker->addShape(Rect(p.x() - kBumpMarkerHalfSize,
                            p.y() - kBumpMarkerHalfSize,
                            p.x() + kBumpMarkerHalfSize,
                            p.y() + kBumpMarkerHalfSize));
      dbChipRegion* chip_region = chip_bump->getChipRegion();
      marker->setComment(fmt::format(
          "Bump {} in region {} has no pin geometry on the region's "
          "declared contact layer {}",
          inst->getName(),
          chip_region->getName(),
          chip_region->getLayer()->getName()));
    }
  }

[osamahammad21]

ditto

[gemini-code-assist]

If warnIfMultiPinBumpMaster is called with a null master pointer, it will cause a null pointer dereference and crash. Adding a defensive null check at the beginning of the function ensures safety.

void ThreeDBlox::warnIfMultiPinBumpMaster(dbMaster* master)
{
  if (master == nullptr) {
    return;
  }
  // Downstream code (net hookup, bpin creation, face inference) assumes a
  // bump cell exposes exactly one pin.
  if (master->getMTermCount() != 1
      && multi_pin_warned_masters_.insert(master).second) {
    logger_->warn(utl::ODB,
                  557,
                  "Bump cell {} has {} pins; bump cells are expected to have "
                  "exactly one pin",
                  master->getName(),
                  master->getMTermCount());
  }
}

[osamahammad21]

ditto