--- /dev/null
+module latchp
+ ( input d, en, output reg q );
+ always @*
+ if ( en )
+ q <= d;
+endmodule
+
+module latchn
+ ( input d, en, output reg q );
+ always @*
+ if ( !en )
+ q <= d;
+endmodule
+
+module latchsr
+ ( input d, en, clr, pre, output reg q );
+ always @*
+ if ( clr )
+ q <= 1'b0;
+ else if ( pre )
+ q <= 1'b1;
+ else if ( en )
+ q <= d;
+endmodule
+
+
+module top (
+input clk,
+input clr,
+input pre,
+input a,
+output b,b1,b2
+);
+
+
+latchp u_latchp (
+ .en (clk ),
+ .d (a ),
+ .q (b )
+ );
+
+
+latchn u_latchn (
+ .en (clk ),
+ .d (a ),
+ .q (b1 )
+ );
+
+
+latchsr u_latchsr (
+ .en (clk ),
+ .clr (clr),
+ .pre (pre),
+ .d (a ),
+ .q (b2 )
+ );
+
+endmodule
--- /dev/null
+read_verilog latches.v
+
+proc
+flatten
+equiv_opt -assert -run :prove -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
+async2sync
+equiv_opt -assert -run prove: -map +/xilinx/cells_sim.v synth_xilinx # equivalency check
+
+design -load preopt
+synth_xilinx
+cd top
+select -assert-count 1 t:LUT1
+select -assert-count 2 t:LUT3
+select -assert-count 3 t:LDCE
+select -assert-none t:LUT1 t:LUT3 t:LDCE %% t:* %D