vcs option and udpsched in gate-level simulation without delay

Upon activation of the udpsched switch, VCS manages events that update sequential UDP outputs by treating them as non-blocking assignments. This ensures that non-blocking assignment scheduling aligns with RTL code structure while eliminating potential inconsistencies in assignment timing.

Consider this simple example:

module test(input clk,rst, output reg x,y);

always @(posedge clk, negedge rst) if (!rst) x <= 0; else x <= y;

always @(posedge clk,negedge rst) if (!rst) y <= 1; y <= x; endmodule

Upon reaching the reset condition, x becomes 0 while y assumes the value of 1. Upon each subseq