Netlist Objects with DONT_TOUCH Properties - 2025.2 English - UG906

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)
Document ID
UG906
Release Date
2025-12-10
Version
2025.2 English

Netlist objects with DONT_TOUCH properties can block optimizations that would otherwise improve design performance. This section of the QoR Assessment report identifies the objects that have the DONT_TOUCH property set.

The report includes:

  • Hierarchical cells
  • Leaf cells
  • Nets
Figure 1. Netlist Objects with DONT_TOUCH Property

The cause for each setting is also shown.

Note: The DONT_TOUCH property prevents the tools from optimizing the associated paths. Vivado might automatically apply this property through other design attributes. Remove DONT_TOUCH properties only when appropriate. For example:
  • The DFX flow uses DONT_TOUCH to prevent cross-boundary optimization between static and reconfigurable modules. In this case, do not remove the property.
  • If DONT_TOUCH was added through MARK_DEBUG, it is not critical to the design flow. However, removing it could make the signal unavailable for hardware probing if the tool optimizes it away.