Configuring the Incremental Flow - 2023.1 English

UltraFast Design Methodology Guide for FPGAs and SoCs (UG949)

Document ID
UG949
Release Date
2023-06-07
Version
2023.1 English

You can configure the incremental flow using the config_implementation command. To view the default and current values of this command use the report_config_implementation command. To update these values use the config_implementation command. Following is an example:

report_config_implementation
config_implementation { {incr.ignore_user_clock_uncertainty true} }
Note: You can update more than one element at a time by grouping key value pairs in the same method shown above within the outer brackets.

You can configure the following:

  • Minimum thresholds for cell matching, net matching, and WNS in the automatic incremental flow.
  • Behavior of both synthesis and implementation when the automatic incremental flow criteria is not met. This check happens at the beginning of the synthesis run and during read_checkpoint -incremental for implementation. It can be set to Terminate which stops the flow or SwitchToDefaultFlow which exits the incremental flow but continues with default flow settings.
  • Whether the flow ignores user clock uncertainty constraints that are typically used to overconstrain the placer and force closer placement.