Exploiting ArchitectureFor Verification

Dave Whipp

Architecture For Verification Simplify the Design

– Reduce corner cases– Decoupled State Machines– Focus Complexity on Performance

• Tradeoff Performance Vs Schedule

Provide Verification-Friendly Work Products– Models– Test benches– Tests

A HW Development FlowBig Paper Spec

Design

Verification

RTL

Testbench Checkers Tests

Scoreboard

Assertions

C Model

Synthesis

Directed

RandomsBFMs,

TLMs

Clocks, ResetsAssertions

ISS Model

CoverageDebug

(BAD)

A HW Development FlowBig Paper Spec

Design

Verification

RTL

Testbench Checkers Tests

Scoreboard

Assertions

C Model

Synthesis

Directed

RandomsBFMs,

TLMs

Clocks, ResetsAssertions

ISS Model

CoverageDebug

(BAD)

A HW Development Flow (Better)

RTL Scoreboards

Synthesis

Randoms

Clocks, Resets

Design

Verification

Testbench

Small Paper Spec

ISS Model ESL

C Model

Interfaces

Assertions

Directed Tests BFMs

TLMs

Validation

Assertions

Triage

Debug

Coverage

Coverage

What Type of Model?

A EB C D F G

D

GA

BE

CF

How do we model that these are equivalent?

ISS:

TLM:

Exploitation of Executable Models Product Development

– Enable SW development– Validate the Architecture

Verification Bootstrapping– Validate Tests– Functional Checkers– Validate Assertions– Architectural Coverage

Design Verification Testbenches

TransactionProducer

ScenarioGenerator

CoverageModel

DUT

TransactionConsumer

ScenarioChecker

BFM BFM

UTFmodel

Architectural Validation Testbenches

TransactionProducer

ScenarioGenerator

CoverageModel

UTFmodel

TransactionConsumer

ScenarioChecker

How To Reuse Architectural Tests

Architectural

Mic

ro A

rchi

tect

ural

Architectural Bringup Tests

Architectural

Mic

ro A

rchi

tect

ural

Micro-architectural Directed Tests

Architectural

Mic

ro A

rchi

tect

ural

Micro-architectural Directed Tests

Shallow Features

Dee

p In

tera

ctio

ns

Constrained Random Tests

Shallow Features

Dee

p In

tera

ctio

ns

Random Directed Tests

Shallow Features

Dee

p In

tera

ctio

ns

Testing using GraphsShape

Line

Triangle

Solid

Stipple

Short Fat

Long Skinny Filled

Outline

Aspect Body

Dashed

Micro-Architectural Tests

Address Cacheable

Page

Evict dirty

Evict about-to-be-needed

Reuse

New

No

Yes

Conclusion Architects must create Executable

Representations– Validated by Architects– Reused by Verifiers

Not Just Models– Testbenches and VIP– Self-Checking Tests (Directed Random)

Traditional Models serve Multiple Roles– Checkers– Assertions– Coverage