Incremental Directives and Target WNS - 2023.2 English

UltraFast Design Methodology Guide for FPGAs and SoCs (UG949)

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2023.2 English

You can use incremental directives to specify the target WNS for the implementation flow. The target WNS determines whether the implementation tools try to close timing or only try to achieve the same level of timing closure as the reference checkpoint. When the implementation flow uses the default algorithms, the incremental directive is ignored and the place_design and route_design directives are used.

The following table shows each incremental directive and the corresponding target WNS behavior.

Table 1. Incremental Directive and Target WNS Behavior
Incremental Directive Target WNS Behavior
RuntimeOptimized Same as the reference checkpoint
TimingClosure 0.000
Quick Flow is not timing driven, and placement is driven by related logic
Note: Incremental directives replace directive mapping from previous releases.