equivalent tiles: corrected equivalent placement in func find_to

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

Author: acomodi

vpr/src/place/place.cpp

@@ -1835,12 +1835,19 @@ static e_swap_result try_swap(float t,
 	VTR_ASSERT(cluster_from_type->is_available_tile_index(grid_from_type->index));
 
 	t_type_ptr to_block_type = cluster_ctx.clb_nlist.block_type(b_from);
-	int rand_block_type = vtr::irand(to_block_type->num_equivalent_tiles);
-	if (rand_block_type != 0) {
-		auto result = to_block_type->equivalent_tiles.find(rand_block_type-1);
-		VTR_ASSERT(result != to_block_type->equivalent_tiles.end());
 
-		to_block_type = result->second;
+
+	// Find random equivalent type (could be of the same type as the `from` one)
+	if (to_block_type->num_equivalent_tiles > 0) {
+		int irand_block_type = std::rand() % (to_block_type->num_equivalent_tiles + 1);
+
+		// If random index is 0 do not use an equivalent tile.
+		if (irand_block_type > 0) {
+			auto result = to_block_type->equivalent_tiles.find(irand_block_type - 1);
+			VTR_ASSERT(result != to_block_type->equivalent_tiles.end());
+
+			to_block_type = result->second;
+		}
 	}
 
 	VTR_ASSERT(cluster_from_type->is_available_tile_index(to_block_type->index));
@@ -2145,7 +2152,7 @@ static bool find_to(t_type_ptr to_type, t_type_ptr from_type, float rlim, const
     int min_cy, max_cy;
     int delta_cx;
 
-    //Determin the valid compressed grid location ranges
+    //Determine the valid compressed grid location ranges
     if (to_type == from_type) {
         min_cx = std::max(0, cx_from - rlim_x);
         max_cx = std::min<int>(to_compressed_block_grid.compressed_to_grid_x.size() - 1, cx_from + rlim_x);