diff --git a/vpr/src/base/region.cpp b/vpr/src/base/region.cpp
index 2035a57e717..ed5b79c068b 100644
--- a/vpr/src/base/region.cpp
+++ b/vpr/src/base/region.cpp
@@ -81,20 +81,36 @@ bool do_regions_intersect(Region r1, Region r2) {
 
 Region intersection(const Region& r1, const Region& r2) {
     Region intersect;
+    vtr::Rect<int> r1_rect = r1.get_region_rect();
+    vtr::Rect<int> r2_rect = r2.get_region_rect();
+    vtr::Rect<int> intersect_rect;
 
-    /**
-     * If the subtiles of the two regions don't match, there is no intersection.
-     * If they do match, the intersection function if used to get the overlap of the two regions' rectangles.
-     * If there is no overlap, an empty rectangle will be returned.
+    /*
+     * If the subtiles of two regions match (i.e. they both have no subtile specified, or the same subtile specified),
+     * the regions are intersected. The resulting intersection region will have a rectangle that reflects their overlap,
+     * (it will be empty if there is no overlap), and a subtile that is the same as that of both regions.
+     *
+     * If one of the two regions has a subtile specified, and the other does not, the regions are intersected.
+     * The resulting intersection region will have a rectangle that reflects their overlap (it will be empty if there is
+     * no overlap), and a subtile that is the same as the subtile of the region with the specific subtile assigned.
+     *
+     * If none of the above cases are true (i.e. the regions both have subtiles specified, but the subtiles do not
+     * match each other) then the intersection is not performed and a region with an empty rectangle is returned.
+     * This is because there can be no overlap in this case since the regions are constrained to two separate subtiles.
      */
     if (r1.get_sub_tile() == r2.get_sub_tile()) {
         intersect.set_sub_tile(r1.get_sub_tile());
-        vtr::Rect<int> r1_rect = r1.get_region_rect();
-        vtr::Rect<int> r2_rect = r2.get_region_rect();
-        vtr::Rect<int> intersect_rect;
+        intersect_rect = intersection(r1_rect, r2_rect);
+        intersect.set_region_rect(intersect_rect.xmin(), intersect_rect.ymin(), intersect_rect.xmax(), intersect_rect.ymax());
 
+    } else if (r1.get_sub_tile() == NO_SUBTILE && r2.get_sub_tile() != NO_SUBTILE) {
+        intersect.set_sub_tile(r2.get_sub_tile());
         intersect_rect = intersection(r1_rect, r2_rect);
+        intersect.set_region_rect(intersect_rect.xmin(), intersect_rect.ymin(), intersect_rect.xmax(), intersect_rect.ymax());
 
+    } else if (r1.get_sub_tile() != NO_SUBTILE && r2.get_sub_tile() == NO_SUBTILE) {
+        intersect.set_sub_tile(r1.get_sub_tile());
+        intersect_rect = intersection(r1_rect, r2_rect);
         intersect.set_region_rect(intersect_rect.xmin(), intersect_rect.ymin(), intersect_rect.xmax(), intersect_rect.ymax());
     }
 
diff --git a/vpr/src/place/initial_placement.cpp b/vpr/src/place/initial_placement.cpp
index d5662af4f47..8bda8f3d3a2 100644
--- a/vpr/src/place/initial_placement.cpp
+++ b/vpr/src/place/initial_placement.cpp
@@ -47,9 +47,9 @@ static t_physical_tile_type_ptr pick_placement_type(t_logical_block_type_ptr log
 vtr::vector<ClusterBlockId, t_block_score> assign_block_scores();
 
 //Sort the blocks according to how difficult they are to place, prior to initial placement
-std::vector<ClusterBlockId> sort_blocks(vtr::vector<ClusterBlockId, t_block_score> block_scores);
+std::vector<ClusterBlockId> sort_blocks(const vtr::vector<ClusterBlockId, t_block_score>& block_scores);
 
-void print_sorted_blocks(std::vector<ClusterBlockId> sorted_blocks, vtr::vector<ClusterBlockId, t_block_score> block_scores);
+void print_sorted_blocks(const std::vector<ClusterBlockId>& sorted_blocks, const vtr::vector<ClusterBlockId, t_block_score>& block_scores);
 
 static int get_free_sub_tile(std::vector<std::vector<int>>& free_locations, int itype, std::vector<int> possible_sub_tiles) {
     for (int sub_tile : possible_sub_tiles) {
@@ -359,6 +359,12 @@ vtr::vector<ClusterBlockId, t_block_score> assign_block_scores() {
 
     block_scores.resize(blocks.size());
 
+    /*
+     * For the blocks with no floorplan constraints, and the blocks that are not part of macros,
+     * the block scores will remain at their default values assigned by the constructor
+     * (macro_size = 0; floorplan_constraints = 0; num_equivalent_tiles =1;
+     */
+
     //go through all blocks and store floorplan constraints and num equivalent tiles
     for (auto blk_id : blocks) {
         if (is_cluster_constrained(blk_id)) {
@@ -380,7 +386,7 @@ vtr::vector<ClusterBlockId, t_block_score> assign_block_scores() {
     return block_scores;
 }
 
-std::vector<ClusterBlockId> sort_blocks(vtr::vector<ClusterBlockId, t_block_score> block_scores) {
+std::vector<ClusterBlockId> sort_blocks(const vtr::vector<ClusterBlockId, t_block_score>& block_scores) {
     auto& cluster_ctx = g_vpr_ctx.clustering();
 
     auto blocks = cluster_ctx.clb_nlist.blocks();
@@ -400,7 +406,7 @@ std::vector<ClusterBlockId> sort_blocks(vtr::vector<ClusterBlockId, t_block_scor
     return sorted_blocks;
 }
 
-void print_sorted_blocks(std::vector<ClusterBlockId> sorted_blocks, vtr::vector<ClusterBlockId, t_block_score> block_scores) {
+void print_sorted_blocks(const std::vector<ClusterBlockId>& sorted_blocks, const vtr::vector<ClusterBlockId, t_block_score>& block_scores) {
     VTR_LOG("\nPrinting sorted blocks: \n");
     for (unsigned int i = 0; i < sorted_blocks.size(); i++) {
         VTR_LOG("Block_Id: %zu, Macro size: %d, Num floorplan constraints: %d, Num equivalent tiles %d \n", sorted_blocks[i], block_scores[sorted_blocks[i]].macro_size, block_scores[sorted_blocks[i]].floorplan_constraints, block_scores[sorted_blocks[i]].num_equivalent_tiles);