Re: Attributes and constant expressions

From: Adam Krolnik (krolnik@lsil.com)
Date: Wed Oct 24 2001 - 15:17:23 PDT

Precedence: bulk

<p><p>Good afternoon;

<p>I don't understand the desire to replace pragmas with attributes.
I think that the meta comments can stay and attributes can be
there as well. Developers should pick the element that works best.

For example, surelint allows embedded directives to control
lint reporting.

You can say

 begin
...
  a = b + c; //surefire lint_off_line LINT_CODE

And it will not produce any report of the type LINT_CODE.

This could be translated to attributes:

(* surefire_lint_off=LINT_CODE *)
a = b + c;

(I converted lint_off_line to lint_off since it is directly attributed
to a particular element of the language.)

You can also say

//surefire lint_off SYN

// Here's some verification code that I don't want to have
// any lint reports of the synthesis group.
always @(*)
  begin
  ...
  end

// Turn it back on again.
//surefire lint_on SYN

Which is just like the synopsys translate pragmas. Note that this
doesn't disable the parsing, but the analyzing - and only some
of the analysis is omitted.

Now you could use the Mac_attribute trick to convert the comment pragmas
into attributes. Too bad I didn't make this request:

[Desire a new block type - final that runs once, before the simulation
terminates. The purpose is to do some code before the simulation exits.
Syntax - 'final <statement>']

Then Mac's trick would look like

initial (* synthesis=0 *);
...
final (* synthesis=1 *);

<p>a (* ripple_add *) + b

<p>For verilog parser people (or verilog parser scripters) is there a
decided ease for stylistic comments vs. attributes? From the
parsers I have written, I don't see an advantage.

I do see an advantage for attributes when you are not in the
parser tool game. I as a simple developer want tools that can handle
attributes so that I can put in my information and have tools that
allow me to extract that information. So if I have a parser tool,
I want to extract the attribute values for a given element. I want
to be able to do different things based on the attributes. Some
compilers will create and read the attributes to do defined things.

<p><p><p> Adam Krolnik
     Verification Mgr.
     LSI Logic Corp.
     Plano TX. 75074

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