April 30, 2014 1

A New Tool forDesigner-Level Verification:

From Concept to Reality

April 30, 2014

Ziv Nevo

IBM Haifa Research Lab

April 30, 2014 2

Overview

• Designer-level verification (DLV)

• DLV tools: historical perspective at IBM

• Our latest recipe

April 30, 2014 3

Designer-level verification (DLV)

April 30, 2014 4

Life without DLV

Logic designerVerification

engineer

spec-------

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spec-------

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RTL

April 30, 2014 5

Weeks later…

Logic designerVerification

engineer

spec-------

---

spec-------

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fail

trace

April 30, 2014 6

DLV ≈ “Developer testing”(standard practice in SW)

Verification

engineerLogic designer

RTL

Basic checks

April 30, 2014 7

What activities does DLV include?

Observing mainstream

behavior

Exploring corner cases

Checking assertions

and coverage

points

Bug hunting

Debugging

Observation

Lightweight verification

April 30, 2014 8

Verification: tools of the trade• Simulator• Testbench• HVL• Methodology• Scripts• Formal• Assertions• Coverage• …

Logic designer

Verification engineer

April 30, 2014 9

DLV: what should the tools be?

Logic designer

• Simulator• Testbench• HVL• Methodology• Scripts• Formal• Assertions• Coverage• …

April 30, 2014 10

DLV tools: historical perspective at IBM

April 30, 2014 11

Idea 1: TIMEDIAG (1997)

Specify input value/function/random

Loop cycle (count/random/condition)

April 30, 2014 12

Idea 1: TIMEDIAG (1997)

GenRand

Random instantiation Simulation Checking

April 30, 2014 13

TIMEDIAG ingredients

simulation

Waveform-based

interface complex interleavings

What’s missing?

• Interactive define/run/view

• Event-guided test cases

• Formal analysis

April 30, 2014 14

What activities does DLV include?

Observing mainstream

behavior

Exploring corner cases

Checking assertions

and coverage

points

Bug hunting

Debugging

Observation

Lightweight verification

April 30, 2014 15

Idea 2: PathFinder (2002)

Define events

View trace

Find a trace(formal analysis)

April 30, 2014 16

Idea 2: PathFinder (2002)Main flow:• Specify events• Find trace• View trace

Minor feature:• Edit inputs on

waveform• Simulate

April 30, 2014 17

PathFinder ingredients

waveform-based

interfacesimulation

Interactive define/run/view

Event-guided

test cases

Formal analysis

What’s missing?• Simple driving

(default is random)• Fast simulation• Integration with

common tools

April 30, 2014 18

What activities does DLV include?

Observing mainstream

behavior

Exploring corner cases

Checking assertions

and coverage

points

Bug hunting

Debugging

Observation

Lightweight verification

April 30, 2014 19

Another DLV tool

April 30, 2014 20

Jasper Visualize

April 30, 2014 21

Our latest recipe

April 30, 2014 22

Latest recipe: DiverMain flow

Specify inputs

Simulate

View trace

IBM Debug and Verification Tool for Designers (DIVER)

scenario editor

Specify expected results

View unexpected results

April 30, 2014 23

Latest recipe: DiverAdditional variations

Repetitions and delays

Specify events on outputs

Run-to-failure

Simulate or run formal engine

Assertions and coverage

April 30, 2014 24

Debugging

Import trace

Trace from simulation of integrated component

Scenario for designer-level component

April 30, 2014 25

Diver ingredients

simulation

Waveform-based

interface

Interactive define/run/view

Event-guided

test casesFormal analysis

Climate for DLV

April 30, 2014 26

What activities does DLV include?

Observing mainstream

behavior

Exploring corner cases

Checking assertions

and coverage

points

Bug hunting

Debugging

Observation

Lightweight verification

April 30, 2014 27

Conclusions• DLV activity should scale linearly with the amount

of effort spent

• Recommended recipe:– Waveform-based interface– Interactive define/run/view– Integration with common tools

– Driving inputs– Simulation

– Event-based test cases– A touch of formal analysis

April 30, 2014 28

Questions?