lookahead_cost: avoid building the segment map

Signed-off-by: Alessandro Comodi <[email protected]>

Author: acomodi

vpr/src/route/router_lookahead_cost_map.cpp

@@ -46,20 +46,6 @@ static vtr::Point<T> closest_point_in_rect(const vtr::Rect<T>& r, const vtr::Poi
     }
 }
 
-// build the segment map
-void CostMap::build_segment_map() {
-    const auto& device_ctx = g_vpr_ctx.device();
-    segment_map_.resize(device_ctx.rr_nodes.size());
-    for (size_t i = 0; i < segment_map_.size(); ++i) {
-        auto& from_node = device_ctx.rr_nodes[i];
-
-        int from_cost_index = from_node.cost_index();
-        int from_seg_index = device_ctx.rr_indexed_data[from_cost_index].seg_index;
-
-        segment_map_[i] = from_seg_index;
-    }
-}
-
 // resize internal data structures
 void CostMap::set_counts(size_t seg_count) {
     cost_map_.clear();
@@ -73,7 +59,12 @@ void CostMap::set_counts(size_t seg_count) {
 
 // cached node -> segment map
 int CostMap::node_to_segment(int from_node_ind) const {
-    return segment_map_[from_node_ind];
+    const auto& device_ctx = g_vpr_ctx.device();
+
+    auto& from_node = device_ctx.rr_nodes[from_node_ind];
+
+    int from_cost_index = from_node.cost_index();
+    return device_ctx.rr_indexed_data[from_cost_index].seg_index;
 }
 
 static util::Cost_Entry penalize(const util::Cost_Entry& entry, int distance, float penalty) {
@@ -425,7 +416,6 @@ static void FromFloat(VprFloatEntry::Builder* out, const float& in) {
 }
 
 void CostMap::read(const std::string& file) {
-    build_segment_map();
     MmapFile f(file);
 
     ::capnp::ReaderOptions opts = default_large_capnp_opts();

vpr/src/route/router_lookahead_cost_map.h

@@ -30,12 +30,7 @@ class CostMap {
     void set_counts(size_t seg_count);
 
     /**
-     * @brief Builds a node to segments map for a fast lookup
-     */
-    void build_segment_map();
-
-    /**
-     * @brief Queries the segment map to get the segment index given the corresponding node index
+     * @brief Gets the segment index relative to the input node index
      *
      * @param from_node_ind index of the node to search in the segment map
      * @return The index of the segment corresponding to the input node id
@@ -103,8 +98,6 @@ class CostMap {
                                  ///<delta locations that fall outside of a segment's bounding box.
                                  ///<The penalty map is addressed as follows penalty_[0][segment_index]
 
-    std::vector<int> segment_map_; ///<Segment map to lookup to the segment index given the node index
-
     size_t seg_count_; ///<Total segment count in the architecture
 
     /**

vpr/src/route/router_lookahead_extended_map.cpp

@@ -394,7 +394,6 @@ void ExtendedMapLookahead::compute(const std::vector<t_segment_inf>& segment_inf
     /* free previous delay map and allocate new one */
     auto& device_ctx = g_vpr_ctx.device();
     cost_map_.set_counts(segment_inf.size());
-    cost_map_.build_segment_map();
 
     VTR_ASSERT(REPRESENTATIVE_ENTRY_METHOD == util::SMALLEST);
     util::RoutingCosts all_delay_costs;