grt: Introduce AccessPointMap type alias (cugr)

Signed-off-by: Matt Liberty <[email protected]>

Author: maliberty

src/grt/src/cugr/src/GridGraph.cpp

@@ -352,12 +352,9 @@ CostT GridGraph::getViaCost(const int layer_index, const PointT loc) const
   return cost;
 }
 
-void GridGraph::selectAccessPoints(
-    const GRNet* net,
-    robin_hood::unordered_map<uint64_t, AccessPoint>& selected_access_points)
-    const
+GridGraph::AccessPointMap GridGraph::selectAccessPoints(const GRNet* net) const
 {
-  selected_access_points.clear();
+  AccessPointMap selected_access_points;
   // cell hash (2d) -> access point, fixed layer interval
   selected_access_points.reserve(net->getNumPins());
   const auto& boundingBox = net->getBoundingBox();
@@ -412,6 +409,7 @@ void GridGraph::selectAccessPoints(
     fixedLayers.SetHigh(
         std::min(fixedLayers.high() + 2, (int) getNumLayers() - 1));
   }
+  return selected_access_points;
 }
 
 void GridGraph::commit(const int layer_index,

src/grt/src/cugr/src/GridGraph.h

@@ -81,9 +81,8 @@ class GridGraph
     IntervalT layers;
   };
 
-  void selectAccessPoints(const GRNet* net,
-                          robin_hood::unordered_map<uint64_t, AccessPoint>&
-                              selected_access_points) const;
+  using AccessPointMap = robin_hood::unordered_map<uint64_t, AccessPoint>;
+  AccessPointMap selectAccessPoints(const GRNet* net) const;
 
   // Methods for updating demands
   void commitTree(const std::shared_ptr<GRTreeNode>& tree, bool rip_up = false);

src/grt/src/cugr/src/MazeRoute.cpp

@@ -23,9 +23,7 @@ void SparseGraph::init(const GridGraphView<CostT>& wire_cost_view,
                        const SparseGrid& grid)
 {
   // 0. Create pseudo pins
-  robin_hood::unordered_map<uint64_t, GridGraph::AccessPoint>
-      selectedAccessPoints;
-  grid_graph_->selectAccessPoints(net_, selectedAccessPoints);
+  const auto selectedAccessPoints = grid_graph_->selectAccessPoints(net_);
   pseudo_pins_.reserve(selectedAccessPoints.size());
   for (const auto& selectedPoint : selectedAccessPoints) {
     pseudo_pins_.push_back(selectedPoint.second);

src/grt/src/cugr/src/PatternRoute.cpp

@@ -79,16 +79,13 @@ std::string PatternRoutingNode::getPythonString(
 
 void PatternRoute::constructSteinerTree()
 {
-  robin_hood::unordered_map<uint64_t, GridGraph::AccessPoint>
-      selectedAccessPoints;
-  grid_graph_->selectAccessPoints(net_, selectedAccessPoints);
+  auto selectedAccessPoints = grid_graph_->selectAccessPoints(net_);
 
   const int degree = selectedAccessPoints.size();
   if (degree == 1) {
-    for (auto& accessPoint : selectedAccessPoints) {
-      steiner_tree_ = std::make_shared<SteinerTreeNode>(
-          accessPoint.second.point, accessPoint.second.layers);
-    }
+    const auto& accessPoint = *selectedAccessPoints.begin();
+    steiner_tree_ = std::make_shared<SteinerTreeNode>(
+        accessPoint.second.point, accessPoint.second.layers);
     return;
   }