module top_module (
    input clk,
    input x,
    output z
); 
    
    reg [2:0] Q;
    always@(posedge clk)
        begin
            Q[0] <= Q[0] ^ x;
            Q[1] <= (~Q[1]) & x;
            Q[2] <= (~Q[2]) | x;
            z <= ~(| Q[2:0]); //错误！！！！
        end
    
endmodule

正确答案：

module top_module (
    input clk,
    input x,
    output z
); 
    
    reg [2:0] Q;
    assign z = ~(| Q[2:0]);
    always@(posedge clk)
        begin
            Q[0] <= Q[0] ^ x;
            Q[1] <= (~Q[1]) & x;
            Q[2] <= (~Q[2]) | x;
        end    

endmodule