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A Method for Identifying Datapath Behavior in a Sequential Design

IP.com Disclosure Number: IPCOM000198192D
Publication Date: 2010-Jul-29
Document File: 3 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for identifying conditions under which a given latch behaves as if it were a datapath latch. It does this by finding conditions under which flipping the value stored at the latch will not result in incorrect design behavior. Analysts can then ignore the latch under these conditions during design verification and during certain times in synthesis.

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A Method for Identifying Datapath Behavior in a Sequential Design

Latches are the state-holding elements in a design, and are the cause of most of the

algorithmic complexity in both synthesis and verification. Often, there exist latches that

do not store the internal state of the design but merely exist to temporarily store data as

it flows through the design. Engineers often refer to these latches as datapath latches.

If an engineer or analyst knows apriori which latches are datapath, then they can

exclude these latches from the design analysis, resulting in a dramatic improvement in

the runtimes of both synthesis and verification.

The method described here is able to find all datapath latches as well as latches that

merely assume a datapath-like behavior for a brief time. The invention is a method that

can be used to find conditions under which a given latch behaves as if it were a

datapath latch. It does this by finding conditions under which flipping the value stored at

the latch will not result in incorrect design behavior. Therefore, analysts can ignore the

latch under these conditions during design verification and during certain times in

synthesis. (This is a generalization of datapath latches because for a datapath latch, the

value of the latch is never important to the analysis.)

The implementation of this method is as follows, and works best with small benchmarks:
1. The analyst performs the computation with respect to a latch that is a datapath

candidate.
Example:
•...