yosys/tests/xilinx/adffs.ys

read_verilog adffs.v
design -save read

proc
hierarchy -top adff
equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
cd adff # Constrain all select calls below inside the top module
select -assert-count 1 t:BUFG
select -assert-count 1 t:FDCE
select -assert-none t:BUFG t:FDCE %% t:* %D

design -load read
proc
hierarchy -top adffn
equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
cd adffn # Constrain all select calls below inside the top module
select -assert-count 1 t:BUFG
select -assert-count 1 t:FDCE
select -assert-count 1 t:LUT1
select -assert-none t:BUFG t:FDCE t:LUT1 %% t:* %D

design -load read
proc
hierarchy -top dffs
equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
cd dffs # Constrain all select calls below inside the top module
select -assert-count 1 t:BUFG
select -assert-count 1 t:FDRE
select -assert-count 1 t:LUT2
select -assert-none t:BUFG t:FDRE t:LUT2 %% t:* %D

design -load read
proc
hierarchy -top ndffnr
equiv_opt -assert -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
cd ndffnr # Constrain all select calls below inside the top module
select -assert-count 1 t:BUFG
select -assert-count 1 t:FDRE_1
select -assert-count 1 t:LUT2
select -assert-none t:BUFG t:FDRE_1 t:LUT2 %% t:* %D