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how to remove constant value flops?

tompy

 Hi :

 I got an IP from vendor. Due to design change, some part of the IP are not needed. Since it is time consuming to ask the vendor to remove those flops, I wish to do it in synthesis. I tied the unused part IP clock port and reset_n port to 0. And I want RTL compiler remove those unclocked/always reset flops.I have try set_attribute optimize_constant_0_seq true unclocke_register

but it doesn't work. Can anyone help me? thx!!

 

/tompy

Parents

  • Hi Tompy,

    RC should have removed the flop you mentioned by default. The setting you specificed is default after all. If that part of the IP is truly dead logic, then RC will more than certainly remove it, even without you having to do anything. Please provide some sample code and maybe we can better help you. I am guessing that either there are still functionality tied to transitive fanin and fanout in that logic or logic is preserved / dont_touch somewhere in your implicit or explicit constraints. I suggest you provide a short RTL example or contact your local AE

     gh-

Reply

  • Hi Tompy,

    RC should have removed the flop you mentioned by default. The setting you specificed is default after all. If that part of the IP is truly dead logic, then RC will more than certainly remove it, even without you having to do anything. Please provide some sample code and maybe we can better help you. I am guessing that either there are still functionality tied to transitive fanin and fanout in that logic or logic is preserved / dont_touch somewhere in your implicit or explicit constraints. I suggest you provide a short RTL example or contact your local AE

     gh-

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