Error: Can’t route signal to atom

Description

If you apply both a FAST_INPUT_REGISTER assignment to an I/O and a D3_DELAY assignment to the associated delay chain, compilation might fail with an error similar to the following:

Error: Can’t route signal "in~input" to atom "io_ff" Error: Can’t fit design in device

Resolution

Do not apply both a D3_DELAY assignment and a FAST_INPUT_REGISTER assignment. You may safely apply either assignment, but not both.