warning in synplify

Hi everybody,

I like know, what means three warning when I synthetize. If you can help me, you can send me a e-mail. thank you everybody.

42:49:42:49|Pruning Register i_enc_high(8 downto 0)

53:4:53:5All reachable assignments to i_bitlen(0) assign '0', register removed by optimization

42:49:42:49|Optimizing register bit pixel_cmpr(0) to a constant 0

28:9:28:16|Input low_part is unused