yosys/tests/opt/opt_share_cat.v

module opt_share_test(
	input [15:0] 	a,
	input [15:0] 	b,
	input [15:0] 	c,
	input [15:0] 	d,
	input 				sel,
	output [63:0] res,
	);

	reg [31: 0] 	cat1 = {a+b, c+d};
	reg [31: 0] 	cat2 = {a-b, c-d};

	assign res = {b, sel ? cat1 : cat2, a};

endmodule