Re: [sv-ec] soft constraints and .size randomization

Ah, thanks.  I was focusing on the wrong part of your question.  Essentially your question is whether if the only constraints on a variable are "discarded" soft constraints, that variable is considered "unconstrained".  It does seem like a sentence clarifying that would be good.

Mark

From: Daniel Mlynek <danielm@aldec.com.pl<mailto:danielm@aldec.com.pl>>
Date: Monday, February 9, 2015 10:09 AM
To: Mark Strickland <mastrick@cisco.com<mailto:mastrick@cisco.com>>
Cc: "sv-ec@eda.org<mailto:sv-ec@eda.org>" <sv-ec@eda.org<mailto:sv-ec@eda.org>>
Subject: Re: [sv-ec] soft constraints and .size randomization

This is special case when is smth is random is decided basing on constraints.
Array size is random when .size is used in constraints.
All other variables are randomized if they are declared as random or used as argument to randomize method or function.


DANiel

W dniu 2/9/2015 3:53 PM, Mark Strickland (mastrick) pisze:
Daniel,

I would think it would have to be "remain to be random but constrain on it should be removed".  Do you see text in the LRM that could suggest soft constraints can control whether randomization happens?

Mark

From: Daniel Mlynek <danielm@aldec.com.pl<mailto:danielm@aldec.com.pl>>
Date: Monday, February 9, 2015 6:52 AM
To: "sv-ec@eda.org<mailto:sv-ec@eda.org>" <sv-ec@eda.org<mailto:sv-ec@eda.org>>
Subject: [sv-ec] soft constraints and .size randomization

See example:
class D;
    rand bit[2:0] arr[]='{1,2};
   rand int a=1,b=10;
    constraint con1 { soft arr.size < a && arr.size > b; }

endclass

D d = new;

module top;
    initial repeat(10) begin
           //d.arr = new[5];
       // d.con1.constraint_mode(0); d.con2.constraint_mode(0);
        assert(d.randomize() with {a<b;}) else $fatal("Randomization failed.");
        $display("%p",d.arr);
    end
endmodule

LRM is not clear what should happen in such case.
"arr" size should not be randomized because soft constraints con1 is discarded by inline constraint.
or
"arr" size should remain to be random but constrain on it should be removed



DANiel


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