The variation aware placement is in progress. I have built up the data structure
 for timing driven placement. In original VPR, the delay between two clbs (or
 Clb and I/O pad) is estimated before placement. In order to estimate such 
delay, the original will route between two clbs (or clb and I/O pad) and 
estimate the delay of the routing tree. In the variation aware placement, 
we should change the routing and delay estimation to consider the spatial 
variation. Now the change of the routing part is in progress.