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AR# 59509

2013.4 Vivado Implementation - RLOC constraints not properly considered when MUXCY cells are transformed into CARRY4 cells.


An issue has been reported where RLOC constraints had been applied to MUXCY cells (in edif) but when the MUXCY cells were transformed into CARRY4 cells in Vivado the grouping did not take into account the RLOC grouping.

As a result, there were CARRY4 cells with conflicting RLOC constraints.

This was because MUXCY cells with the same RLOC value were being transformed into different CARRY4 cells which each inherited that same value.

This caused the shape builder to issue critical warnings because two CARRY4 cells cannot occupy a single slice.


To work around this issue, remove the RLOC constraints from the edif file and instead build the macro with XDC constraints based on the CARRY4 cells.
AR# 59509
Date 04/23/2014
Status Active
Type General Article
  • Kintex-7
  • Artix-7
  • Virtex-7
  • Vivado Design Suite - 2013.4
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