RE: [sv-ac] 1678

Hi Doron,

May be use r1_lv1 instead of unique below ... (r1.lv1 might be
misleading scope/namespace creation issues) to be r1's lv1:

sequence r2;

logic [7:0] lv1;
logic [7:0] unique_lv1;

(b, lv1 = c) ##1
(a, r1_lv1 = 0) ##1 (!a, r1_lv1 = r1_lv1 +lv1)[*0:$] ##1 a ##0 (1, lv1 =
r1_lv1)
##1 (lv1 == d);
endsequence

The adjacent idea (I mentioned on call yesterday) is to *add* (we still
need to explain above for backward compatibility) visibility notions,
instead of just explaining how substitution/passing should work, similar
to classes with a "local"/"public" (default) access to r1's lv1, or
simply just add scoping (drop the local bit :)) so you can say to begin
with:

sequence r2;
//logic [7:0] lv1; // no need ...

(b) ##1
r1 (c) // "c" just an input not inout 
##1 (r1.lv1 == d);
endsequence

This would have same "substitution" semantics but clearer, avoids
shadowing issues, cleaner, easier to write ... BTW, I am not too keen on
adding things, we have to clarify/interpret current LRM anyway, so food
for thought in case we encounter more severe issues in this area.

Thx.
-Bassam.

-----Original Message-----
From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Doron Bustan
Sent: Wednesday, November 15, 2006 8:55 AM
To: sv-ac@eda.org
Subject: [sv-ac] 1678

I open a new bug - 1678 for local variables name clashes:

-------------------------------------------------------------

A naive interpretation of substitution may lead to local variables name
clashing.

Here is an example of name clashing.

sequence r1(lv);
logic [7:0] lv1;

(a, lv1 = 0) ##1 (!a, lv1 = lv1 +lv)[*0:$] ##1 a ##0 (1, lv = lv1); 
endsequence



sequence r2;

logic [7:0] lv1;

(b, lv1 = c) ##1
r1(lv1) 
##1 (lv1 == d);
endsequence



A naive substitution will result in the following:

sequence r2;

logic [7:0] lv1;
logic [7:0] lv1;

(b, lv1 = c) ##1
(a, lv1 = 0) ##1 (!a, lv1 = lv1 +lv1)[*0:$] ##1 a ##0 (1, lv1 = lv1)
##1 (lv1 == d);
endsequence


what we really want is to rename lv1 in r1 to a unique name before the
substitution occurs. Then we get

sequence r2;

logic [7:0] lv1;
logic [7:0] unique_lv1;

(b, lv1 = c) ##1
(a, unique_lv1 = 0) ##1 (!a, unique_lv1 = unique_lv1 +lv1)[*0:$] ##1 a
##0 (1, lv1 = unique_lv1)
##1 (lv1 == d);
endsequence