dc综合warning大全。。。求助

我前仿过了。后仿现在还没加sdf（理想条件下），出现x态。考虑是不是warning导致的内部逻辑不通。
现在把各种警告贴上来，求指点，困扰我好久了。
哪些警告是必须消除的。
第一种：20处左右：Warning:  Undriven register 'r_reg[MEMO][DATAOUT][16]' is connected to primary output 'r_out[MEMO][DATAOUT][16]'. (ELAB-832)
第二种：1处：Warning:  ./encode.vhd:103: DEFAULT branch of CASE statement cannot be reached. (ELAB-311)
第三种：50处：Warning: In design 'rt1553', cell 'C22054' does not drive any nets. (LINT-1)
第四：800多处。Warning: In design 'rt1553', port 'r_out[BLOCK_CIR_ADDRESS][15]' is not connected to any nets. (LINT-28)
第五：70处： Warning: In design 'rt1553', output port 'memi[DATAIN][15]' is connected directly to output port 'r_out[MEMI][DATAIN][15]'. (LINT-31)
第六：3处：Warning: In design 'TOP1553', a pin on submodule 'memory' is connected to logic 1 or logic 0. (LINT-32)
   Pin 'read_b' is connected to logic 1.
第七：90处：   Warning: In design 'TOP1553', net 'memory/data5[0]' has multiple drivers (unknown wired-logic type). (LINT-38)
第八：1处:    Warning: Design 'TOP1553' contains 8 high-fanout nets. A fanout number of 1000 will be used for delay calculations involving these nets. (TIM-134)
第九：1处：  Warning: DesignWare synthetic library dw_foundation.sldb is added to the synthetic_library in the current command. (UISN-40)
第十：150处：  Warning: Unable to determine wired-logic type for multiple-driver net 'memory/data1[12]'. (TRANS-5)
Information: Assuming multiple-driver net 'memory/data1[12]' is a wired-AND. (TRANS-6)
Warning: Unable to determine wired-logic type for multiple-driver net 'memory/data1[13]'. (TRANS-5)
第十一：5000多处：  Warning: Target library contains no replacement for register 'regs/r_sys_reg[MUX1M_10M]' (**FFGEN**). (TRANS-4)
另外。因为有个dpram模块，我使用了shared variable，是不是会导致不可综合啊?
elabrate之前的error：    不知道是不是有影响
Error: Cannot create procedure named 'group_variable' - existing command

表示看不懂什么意思，IC封测吗?

防沉。自己顶起来

额。没大神帮帮我吗