Use the -asynchronous option to create asynchronous groups.
set_clock_groups -name async_clk0_clk1 -asynchronous -group {clk0 usrclk itfclk} \
-group {clk1 gtclkrx gtclktx}If the name of the generated clocks cannot be predicted in advance, use
get_clocks -include_generated_clocks to dynamically retrieve them.
The -include_generated_clocks option is an SDC extension. The previous
example can also be written as:
set_clock_groups -name async_clk0_clk1 -asynchronous \
-group [get_clocks -include_generated_clocks clk0] \
-group [get_clocks -include_generated_clocks clk1]