The Vivado IDE allows you to use one or many constraint files. While using a single constraint file for the entire compilation flow might seem more convenient, it can be a challenge to maintain all the constraints as the design becomes more complex. This is usually the case for designs that use several IP cores or large blocks developed by different teams.
After the timing and physical constraints have been imported, independent of the number
of source files or whether the design is in Project or Non-Project mode, all the
constraints can be exported as a single file with the write_xdc
command. The constraints are written to the specified output file in the same order that
they were read into the project or design. The command line option write_xdc
-type
can be used to select a subset of constraints (timing, physical, or
waiver) to export.