[sv-ac] Is result of disable iff (true_expression) vacuous or true success?

From: <vhdlcohen_at_.....>
Date: Thu Aug 18 2005 - 21:20:06 PDT
IEEE P1800/D5 and SV 3.1a LRM 17.11 is unclear on this issue. LRM 
states "If prior to the completion of that evaluation the reset 
expression becomes true, then the overall evaluation of the 
property_spec is true."
  But a true evaluation can be considered as success, which is not 
really the correct interpretation of a reset of an assertion. If fact, 
in PSL an abort, which is equivalent to a SVA disable, causes an 
"immediate termination of current and future obligations of a property.

  The problem is that a tool vendor can interpret a disable iff 
(true_expression) as success or as vacuous success. That issue needs 
clarification.  I suggest that we clarify the LRM to state something 
like ""If prior to the completion of that evaluation the reset 
expression becomes true, then the overall evaluation of the 
property_spec is true, and is considered a vacuous success".
 Ben
  
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 Ben Cohen Trainer, Consultant, Publisher (310) 721-4830
 http://www.vhdlcohen.com/ ben_ f rom _abv-sva.org
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  * Co-Author: Using PSL/SUGAR for Formal and Dynamic Verification 2nd 
Edition, 2004, ISBN 0-9705394-6-0
  * Real Chip Design and Verification Using Verilog and VHDL, 2002 isbn 
0-9705394-2-8
 * Component Design by Example ", 2001 isbn 0-9705394-0-1
  * VHDL Coding Styles and Methodologies, 2nd Edition, 1999 isbn 
0-7923-8474-1
  * VHDL Answers to Frequently Asked Questions, 2nd Edition, isbn 
0-7923-8115
  
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Received on Thu Aug 18 21:20:23 2005

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