verilog code - need help with Xilinx ISE 10.1 warning

[xman52]

Xilinx ISE 10.1 Warning

Hello
Can anyone help me to solve the following issue?!

Actually, i wrote the verilog code for y cpu datapath. But while synthesizing its showing around 432 warning which is of same kind!!.
The warning that a getting is

************
RNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/MemWrite> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/RegDst> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/alu_src> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/RegWrite> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/alu_opcode_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/alu_opcode_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/alu_opcode_0> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_25_21_4> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_25_21_3> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_25_21_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_25_21_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_25_21_0> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_20_16_4> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_20_16_3> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_20_16_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_20_16_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_15_11_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_15_11_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_15_11_3> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_15_11_4> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <r/reg_20_16_0> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/of_Mem_20_16_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/of_Mem_20_16_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/of_Mem_20_16_0> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/ex_RegWrite> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/ex_MemToReg> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/ex_MemWrite> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/ex_MemRead> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/of_Mem_20_16_3> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <al/of_Mem_20_16_4> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_dst_0> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_dst_1> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_dst_2> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_dst_3> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_dst_4> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1895 - Due to other FF/Latch trimming, FF/Latch <d/d_RegWrite> (without init value) has a constant value of 0 in block <datapath>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:2677 - Node <r/branch> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_31> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_30> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_29> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_28> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_27> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_26> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_25> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_24> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_23> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_22> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_21> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_20> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_19> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_18> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_17> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_16> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_15> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_14> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_13> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_12> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_11> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_10> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_9> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_8> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_7> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_6> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_5> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_4> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_3> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_2> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_1> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <r/reg_pc_0> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <d/dmem_written> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_31> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_30> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_29> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_28> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_27> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_26> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_25> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_24> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_23> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_22> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_21> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_20> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_19> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_18> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_17> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_16> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_15> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_14> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_13> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_12> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_11> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_10> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_9> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_8> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_7> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_6> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_5> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_4> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_3> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_2> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_1> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/branch_address_0> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <al/ex_pc_src> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_0> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_1> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_2> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_3> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_4> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_5> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_6> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_7> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_8> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_9> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_10> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_11> of sequential type is unconnected in block <datapath>.
WARNING:Xst:2677 - Node <i/count_12> of sequential type is unconnected in block <datapath>.



What i came to see in some blogs is that this is trimming done as to optimize the block.!! But what am seeing from the code is that the warning of the above kind is even coming when am assigning my signal to zero at reset!!

What to do now!!?

 

[shanmugaveld]

Xilinx ISE 10.1 Warning

Hi,

warning indicates that value is always "zero"...
i.e the signal is having the constant value and it is not used for any checking condition or assignment.
So for optimization these signals will be removed even if u assigned the signal in reset...

 

[xman52]

Re: Xilinx ISE 10.1 Warning

OK thanks..
So what to do if i want these signal to hold a constant value through out??!!
Think like this, if am having a logic in which i want some constant signals or some register to hold a specific value till the end of my process, so then what should i do?! This warning is coming and what the main problem is the "TRIMMING" that is carried out to optimize! This optimiztion is removing some of my signals when am synthesizing the blocks! So is there any option or way so that i can avoid this optimization!? or remove this TRIMMING !?
:?:

 

[shanmugaveld]

Xilinx ISE 10.1 Warning

I think similar can be done using "parameter" in verilog
am not sure in verilog...
but in VHDL u can declare the value as "constant"...