After read_checkpoint -incremental applies the reference checkpoint to
the current design, the incremental reuse data is retained throughout the flow. If a
checkpoint is saved, then reloaded in the same or a separate Vivado Design Suite session, it remains in incremental compile mode.
Consider the following command sequence:
opt_design; # optimize the current design
read_checkpoint -incremental reference.dcp; # apply reference data to current design write_checkpoint incr.dcp; # save a snapshot of the current design
read_checkpoint incr.dcp
place_design
write_checkpoint top_placed.dcp; # save incremental placement result route_design
Upon read_checkpoint incr.dcp, the Vivado tools
determine that incremental data exists, and the subsequent place_design
and route_design commands run incrementally.
Even if you exit and restart the Vivado Design Suite, in the following
command sequence the route_design command is run in incremental mode,
using the routing data from the original reference checkpoint
reference.dcp:
read_checkpoint top_placed.dcp
phys_opt_design
route_design