RETIMING_BACKWARD - 2025.2 English - UG901

The RETIMING_BACKWARD attribute instructs the tool to move a register backward through logic closer to the sequential driving elements. This attribute is not timing-driven and works regardless of whether the retiming global setting is active or if there are even timing constraints. If the global retiming setting is active, first the RETIMING_BACKWARD step executes, and then global retiming enhances that register to move further back the chain. However, it does not interfere with the attribute and moves the register back to the original location.

The RETIMING_BACKWARD attribute takes an integer as a value. This value describes the amount of logic the register is allowed to cross. Larger values allow the register to cross more logic. 0 turns the attribute off.