综合仿真警告。。 不知道为什么

鄙人近来用MODELSIM&nbsp;SE&nbsp;做仿真<br /><br />做了一个除法器&nbsp;然后仿真后&nbsp;结果是正确的，但是出现大串大串的如下警告<br /><br />Warning:&nbsp;There&nbsp;is&nbsp;an&nbsp;'U'|'X'|'W'|'Z'|'-'&nbsp;in&nbsp;an&nbsp;arithmetic&nbsp;operand,&nbsp;the&nbsp;result&nbsp;will&nbsp;be&nbsp;'X'(es).<br /><br />下边这个是ISE综合时候产生的警告：<br /><br />PACKER&nbsp;Warning:&nbsp;Lut&nbsp;divider__n0003&lt15&gtlut&nbsp;driving&nbsp;carrydivider__n0003&lt15&gtcy&nbsp;can&nbsp;not&nbsp;be&nbsp;packed&nbsp;with&nbsp;the&nbsp;carry&nbsp;due&nbsp;to&nbsp;conflict&nbsp;with&nbsp;the&nbsp;common&nbsp;signal&nbsp;requirement&nbsp;between&nbsp;the&nbsp;LUT&nbsp;inputs&nbsp;and&nbsp;the&nbsp;Carry&nbsp;DI/MAND&nbsp;pins.&nbsp;This&nbsp;would&nbsp;result&nbsp;in&nbsp;an&nbsp;extra&nbsp;LUT&nbsp;for&nbsp;a&nbsp;feedthrough.<br /><br />望指点迷津&nbsp;不甚感激！<br />