A LUT with 500,000 entries? And how many bits is each entry?
I suggest you declare an array and then use the inital block to set the values.
reg [7:0] lut_rom [0:499_999];
integer i;
initial begin
for(i = 0; i < 500_000; i = i+1) begin
lut_rom[i] = ....
end
end
Reads should be performed in such a way that Quartus can infer a synchronous ROM from this. Otherwise, it will probably not fit and/or be very slow.
