Re: [sv-bc] Member select or hierarchical name

From: Surya Pratik Saha <spsaha_at_.....>
Date: Wed Jan 07 2009 - 04:03:52 PST

Hi Shalom,
Darft LRM mentioned:
When a dotted name is encountered at its point of appearance, the first name in the sequence is resolved as though it were a simple identifier.

And if we go by simple identifier searching rule, then 'b1' to be selected as generate block, as the struct is not yet declared. So the 'bl.x' has to be considered as 'hierarchical name' as per the rule <2> mentioned in the section. So your comment saying "bl.x is considered to be a member select of bl.x." is not correct. But my query is - after traversing the whole design, is it required to double check the 'hierarchical name's to convert to 'member select'. In that way, LRM is silent.

Regards
Surya

-------- Original Message  --------
Subject: Re:[sv-bc] Member select or hierarchical name
From: Bresticker, Shalom <shalom.bresticker@intel.com>
To: Surya Pratik Saha <spsaha@cal.interrasystems.com>, sv-bc@eda.org <sv-bc@eda.org>
Date: Wednesday, January 07, 2009 5:21:31 PM

Hi,

This is actually one of the simpler cases and is connected to sections 23.8 and 23.9 as well. 

This whole subject is still far from being adequately described in the LRM, but we try to improve each time.

One of the basic rules is that you look for the first component of the name in the local scope. If you find it, then you go downward from there. If not, then you go upward and try again.

In this case, the first component of bl.x is bl. bl is not declared within the initial procedure, so you go up to the generate block. In this case, bl is declared inside the generate block, as the name of the struct. Then bl.x is considered to be a member select of bl.x.

A more complex case would be if struct bl did not contain a member x. Would it go up to the generate block called bl and the variable int x inside it or would it still consider bl to be a reference to the struct bl and then bl.x would be an error because it does not exist? 

This was ambiguous in previous versions of the standard. This revision attempts to resolve that ambiguity. I believe that the rules defined in 23.7 in this draft will define that bl would resolve to the struct in any case and bl.x would be an error.

Regards,
Shalom

  

-----Original Message-----
From: owner-sv-bc@server.eda.org 
[mailto:owner-sv-bc@server.eda.org] On Behalf Of Surya Pratik Saha
Sent: Wednesday, January 07, 2009 1:26 PM
To: sv-bc@eda.org
Subject: [sv-bc] Member select or hierarchical name

Hi,
I have just gone through the section 23.7 (Member selects and 
hierarchical names). The section seems very interesting. 
However, I am not sure if a hierarchical name will be 
converted to member select or not when the whole scope is 
traversed. For e.g.

module top;
    generate
        begin:bl
            int x;
            initial begin
               bl.x = 1; // will it be converted to member 
select of struct after the full scope is traversed
            end
             struct {int x;} bl;
       end
    endgenerate
endmodule

Please let me know.
Currently all standard simulators consider 'bl.x' as member select.

--
Regards
Surya
    

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