General Description: When inferring a comparator when synthesizing with Synopsys' Design Compiler or FPGA Compiler and targetting a Virtex device, the following error may occur:
Error: Cannot find a valid implementation for module 'xdw_comp_uns'. (SYNH-14)
There is due to a problem with the Xilinx Designware component xdw_comp_uns for Virtex. Design/FPGA Compiler will not be able to finish successfully whenever it infers that component.
解决方案
At this time, there is no workaround. This will be patched in a future service pack for the 2.1i software release.
FPGA Compiler II / FPGA Express do not exhibit this problem.