Formal Verification and Compliance Checkers

by

 

Dr. Saurabh Joshi

Dr. Ramakrishna Upadrasta

Department of CSE, IIT Hyderabad

Indian Institute of Technology Hyderabad

Example

  • Can the assertion fail?
  • 1 million tests says NO
  • Undefined behaviour as per C programming language standard if signed integer arithmetic results in an overflow/underflow
  • Probability that a uniformly randomly generated test would find  the bug is         > 2.1Billion
\frac{2}{2^{32}}

Example

  • What's wrong with this code?

A small software bug can cause a disaster!

  • Ariane 5 : 64-bit FP to 16-bit int
  • Mariner 1: Omission of a hyphen
  • Pentium FDIV bug : $400M+ loss
  • Therac 25 fatal radiation: Race condition
  • and many more...

Testing

  • It can scale to a very large system
  • Well understood by developers
  • Explores a small subset of all possible system behaviour

Err

Start

Formal Verification

  • Can be applied for small modules
  • System represented as a system of equation
  • Exhaustively explores system behaviours
  • Provides functional safety guarantees with respect to the specification
  • Advancement in user-friendly model-checkers

Err

Start

Example

  • Can the assert fail?
  •  

Example

Example

Need for code compliance checker

Formal Verification and Compliance Checkers

By Saurabh Joshi

Formal Verification and Compliance Checkers

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