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

Surya,

 

New terminology added to the LRM section 23.7 is "point of appearance",
which I believe was supposed to be "point of the reference" as defined
by section 26.3 on locally visible identifiers.

 

A decision is supposed to be made from this point of reference without
looking at any of the code forward of it. In the example in 23.7, dotted
name 2 shows the intended behavior.

 

 

Dave

 

 

________________________________

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 4:50 AM
To: Bresticker, Shalom
Cc: sv-bc@eda.org
Subject: Re: [sv-bc] Member select or hierarchical name

 

Hi Shalom,
So can you answer my original query that - is it required to revisit the
'hierarchical name' after completing the traversal of scope to convert
it as 'memory select'. LRM is silent on that.



Regards
Surya



-------- Original Message  --------
Subject: Re:[sv-bc] Member select or hierarchical name
From: Bresticker, Shalom <shalom.bresticker@intel.com>
<mailto:shalom.bresticker@intel.com> 
To: Surya Pratik Saha <spsaha@cal.interrasystems.com>
<mailto:spsaha@cal.interrasystems.com> 
Cc: "sv-bc@eda.org" <mailto:sv-bc@eda.org>  <sv-bc@eda.org>
<mailto:sv-bc@eda.org> 
Date: Wednesday, January 07, 2009 6:12:51 PM



Now I see what you mean.

 

Shalom

	 

	
________________________________


	From: Surya Pratik Saha [mailto:spsaha@cal.interrasystems.com] 
	Sent: Wednesday, January 07, 2009 2:30 PM
	To: Bresticker, Shalom
	Cc: sv-bc@eda.org
	Subject: Re: [sv-bc] Member select or hierarchical name

	Hi Shalom,
	An identifier can't be used as forward reference like task
enable or function call. So for the following example:
	
	module top;
	int x;
	if (1) begin : b // generate block
	initial x = 1; // pointing to 'int x' inside module
	bit x;
	end
	endmodule
	
	The reference 'x' inside initial block is 'int x;' inside
module, not 'bit x' inside generate block.
	
	Now for my earlier example, 'bl' as struct is not yet declared
when 'bl.x' is referred, and it must hit generate block 'bl'. So I am
not sure how you derive rule <1> will be applied here.
	
	

	Regards
	Surya
	    

	
	
	-------- Original Message  --------
	Subject: Re:[sv-bc] Member select or hierarchical name
	From: Bresticker, Shalom <shalom.bresticker@intel.com>
<mailto:shalom.bresticker@intel.com> 
	To: Surya Pratik Saha <spsaha@cal.interrasystems.com>
<mailto:spsaha@cal.interrasystems.com> 
	Cc: "sv-bc@eda.org" <mailto:sv-bc@eda.org>  <sv-bc@eda.org>
<mailto:sv-bc@eda.org> 
	Date: Wednesday, January 07, 2009 5:41:54 PM
	
	

	Hi,

	 

	I can see where you get confused. As I wrote, we still have a
long way to go before the description is complete, precise, and clear.

	 

	In this case, "the first name in the sequence is resolved as
though it were a simple identifier" 

	should point you to 23.9, where it says, 

	"If an identifier is referenced directly (without a hierarchical
path) within a task, function, named block, or generate block, it shall
be declared either within the task, function, named block, or generate
block locally or within a module, interface, program, checker, task,
function, named block, or generate block that is higher in the same
branch of the name tree that contains the task, function, named block,
or generate block. If it is declared locally, then the local item shall
be used; if not, the search shall continue upward until an item by that
name is found or until a module, interface, program, or checker boundary
is encountered."

	 

	As a result bl resolves to the variable declaration. Then rule
<1> applies.

	Shalom

		
________________________________


		From: Surya Pratik Saha
[mailto:spsaha@cal.interrasystems.com] 
		Sent: Wednesday, January 07, 2009 2:04 PM
		To: Bresticker, Shalom
		Cc: sv-bc@eda.org
		Subject: Re: [sv-bc] Member select or hierarchical name

		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>
<mailto:shalom.bresticker@intel.com> 
		To: Surya Pratik Saha <spsaha@cal.interrasystems.com>
<mailto:spsaha@cal.interrasystems.com> , sv-bc@eda.org <sv-bc@eda.org>
<mailto: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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