[sv-ec] query regarding option.detect_overlap

<Forwarding bounced email from Vaibhav Bhutani>

-------- Original Message --------
Message-ID: <4CA98F9E.9070303@cadence.com>
Date: Mon, 4 Oct 2010 13:56:06 +0530
From: Vaibhav Bhutani <vbhutani@cadence.com>
To: <sv-ec@eda.org>, Vaibhav Bhutani <vbhutani@cadence.com>
Subject: query regarding option.detect_overlap

Hi,

Please clarify the expected behavior in following scenario which do not seem to
be very elaborate in the LRM. As per LRM, following is the expected behaviour wrt covergroup
option.detect_overlap
     "When true, a warning is issued if there is an overlap between the
range list (or transition list) of two bins of a coverpoint."

Please let us know what should be the expectation in case of partial overlap in transition list,
eg, would the following code generate such warning:

     covergroup cg1 @(posedge clk);
             option.detect_overlap = 1;
             c1: coverpoint opcode{
                 bins x[] = (0=>1=>2);
                 bins y[] = (0=>1);
             }
     endgroup : cg1

The arguments for and against giving detect_overlap warning are as follows:

For:-
     Just like the ignore/illegal bins behaviour where partial overlap of
transitions bins also generate warning, same can be deduced in detect_overlap

Against:-
     The two transition 0=>1 & 0=>1=>2 represent completely different use
cases, the user may be interested in knowing the hit count separately,
     eg, how many times 0=>1 is hit and how many times 0=>1=>2 is hit

Please let us know what does the user expect from such scenario.

Regds
Vaibhav Bhutani

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