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sub architecture selection

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In a block with deep asynchronous logic, there are some multiplier stages. I synthesized this block stand-alone and "report datapath" does not show me a multiplier architecture for it. Then I have applied following pragma:

assign some_prod[24:0] = {15'h0,some_term1[9:0]} * /* cadence sub_arch booth */ {{10{some_term2[14]}},some_term2[14:0]};

Please note the sign extension for the 2nd term.

Neither elab nor "synthesize -to_generic -effort high" shows me an information about this setting. The results with pragma above are without pragma are the same, ie. pragma does not seem to have an effect.

set_attr user_sub_arch booth [find / -design my_design]

does not work, because the attribute can be assigned only to subdesigns.

The reason why I do this experiment in a stand-alone synthesis is that the runtime of the complete system takes ca. 6 hours.

RC is v06.20-p003_1.

Can the HDL coding style affect the mechanism of inferring synthetic operators?


Originally posted in cdnusers.org by sporadic crash
Parents

  • Grasshopper,

    i have found the reason. The reason is the script I am using is setting input_pragma_keyword attribute a value other than default setting, which does not include the string "cadence" any more. Therefore RTL Compiler does not recognize the cadence inline pragma any more.

    When I keep the attribute input_pragma_keyword in its default value, I get Booth architecture, because RTL Compiler recognizes inline pragma keyword "cadence".

    When I change the value of this attribute in such a way that its value does not include string "cadence", RTL Compiler is unable to recognize the inline pragma keyword "cadence" and thus it does not infer Booth operator.

    But I will contact Cadence to tell them that neither read_hdl nor elaborate produces any message saying that it recognized the inline pragma in the default value of the said attribute.


    Originally posted in cdnusers.org by sporadic crash
Reply

  • Grasshopper,

    i have found the reason. The reason is the script I am using is setting input_pragma_keyword attribute a value other than default setting, which does not include the string "cadence" any more. Therefore RTL Compiler does not recognize the cadence inline pragma any more.

    When I keep the attribute input_pragma_keyword in its default value, I get Booth architecture, because RTL Compiler recognizes inline pragma keyword "cadence".

    When I change the value of this attribute in such a way that its value does not include string "cadence", RTL Compiler is unable to recognize the inline pragma keyword "cadence" and thus it does not infer Booth operator.

    But I will contact Cadence to tell them that neither read_hdl nor elaborate produces any message saying that it recognized the inline pragma in the default value of the said attribute.


    Originally posted in cdnusers.org by sporadic crash
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