In the following figure, a create_generated_clock constraint was defined
on the mixed-mode clock manager (MMCM) instance pin CLKOUT0, but it
does not match the auto-derived waveform generated by Vivado from the
MMCM attribute settings.
To rename the auto-derived clock, add this constraint immediately after defining the master clock in your constraint files:
create_generated_clock -name clkName [get_pins clk_gen_i0/clk_core_i0/inst/mmcme3_adv_inst/CLKOUT0]Figure 1. Invalid Clock Waveform on Clock Modifying Block