RE: [sv-ac] notes from SV-AC meeting 2007-09-25

Erik,


________________________________

	From: Seligman, Erik 
	Sent: Thursday, September 27, 2007 11:11 PM
	To: Bresticker, Shalom; 'john.havlicek@freescale.com'
	Cc: 'sv-ac@server.eda-stds.org'; Korchemny, Dmitry
	Subject: RE: [sv-ac] notes from SV-AC meeting 2007-09-25
	
	
	
	
	"integer my_ints[2] = {123, 456};
	always @(posedge clk) begin
	  foreach (my_ints[i]) begin : b1
	    foo[i] <= somefunction(my_ints[i]);
	    a1: assume property (foo[i] != `BAD_VAL);
	  end
	end
	
	The assumptions b1[0].a1 and b1[1].a1 in this example are
logically equivalent to the assumptions in the example below:"
	
	[SB] Second, there is no b1[0].a1 and b1[1].a1, as I tried to
explain earlier. There is only b1.a1. An array of scopes is created by a
generate for-loop, but not by a regular for-loop.
	

	Well, that's the main idea of this proposal: in previous
language versions a concurrent assertion here would not make sense at
all, so there would be no valid instance name regardless, but now
b1[0].a1 and b1[1].a1 *do* exist, as defined by our rewrite-as-generate
methodology.  Is there a different way you would phrase this
description?

	[SB] You wrote  "The assumptions b1[0].a1 and b1[1].a1 in this
example ".
	But those names do not exist in "this example". You could talk
about the assumptions created on each iteration.

	 
	2. The proposal says, "If the loop is a foreach loop, the
generate block will use a for loop that iterates over the indices used
in the foreach statement."
	
	The problem is that if the foreach is over an associative array,
the indices may be non-contiguous, and then you can't recreate them
using a generate for-loop.
	
	Hmmm....  This language is way too complicated.

	Any objections if we restrict this proposal to foreach
statements with contiguous indices?
	[SB] Maybe better is to restrict it to non-associative arrays.

	 

	Regards,

	Shalom

	 

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