Physical optimization (phys_opt_design)
automatically replicates the high fanout net drivers based on slack and placement
information, and usually significantly improves timing. AMD recommends that you drive high fanout nets with a fabric register
(FD*), which is easier to replicate and relocate during physical optimization.
In some cases, the default phys_opt_design command does not replicate all critical high fanout nets.
Use a different directive to increase the command effort: Explore, AggressiveExplore or
AggressiveFanoutOpt. Also, when a high fanout net becomes critical during routing, you
can add an iteration of phys_opt_design to force
replication on specific nets before trying to route the design again. For example:
phys_opt_design -force_replication_on_nets [get_nets [list netA netB netC]]