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Lazy- CSeq : A Lazy Sequentialization Tool for C

Lazy- CSeq : A Lazy Sequentialization Tool for C. Sequentialization. Basic Idea - code - to -code translation concurrent program P ↝ non-det. sequential program P ' P ' simulates all computations (within certain bounds) of P concurrency in P ↝ non-determinism in P '

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Lazy- CSeq : A Lazy Sequentialization Tool for C

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  1. Lazy-CSeq: A Lazy Sequentialization Tool for C

  2. Sequentialization Basic Idea - code-to-code translation • concurrentprogram P↝ non-det. sequentialprogram P' • P' simulates all computations (within certain bounds) of P • concurrency in P↝ non-determinism in P' • P' analysed using sequential verification tools

  3. Sequentialization Basic Idea - code-to-code translation • concurrentprogram P↝ non-det. sequentialprogram P' • P' simulates all computations (within certain bounds) of P • concurrency in P↝ non-determinism in P' • P' analysed using sequential verification tools Lazy-CSeq schema • P'simulates all computations (up to K rounds) of P • lazy: avoid exploring unfeasible runs T₁ ∥ T₂ ∥ … ∥ Tn↝ (T'1 ; T'2 ; … ; T'n)K

  4. Lazy-CSeqSequentialization Translation P↝ P': • unwinding, inlining • thread T↝ function T' • main driver: • for round in [1..K] • for thread in [1..N] • T'thread ();

  5. Lazy-CSeqSequentialization Translation P↝ P': • unwinding, inlining • thread T↝ function T' • main driver: • for round in [1..K] • for thread in [1..N] • T'thread (); T' guard; stmt; Thread T↝ function T' • var x;↝ staticvar x; • stmt;↝guard; stmt;

  6. Lazy-CSeqSequentialization Translation P↝ P': • unwinding, inlining • thread T↝ function T' • main driver: • for round in [1..K] • for thread in [1..N] • T'thread (); T' exec context-switchp1 skip Thread T↝ function T' • var x;↝ staticvar x; • stmt;↝ guard; stmt; ... ... Threadsimulation: round 1 • guesscontext-switchpointp1 • executestmtsbeforep1 • jump in mult.hops to the end simulation round 1

  7. Lazy-CSeqSequentialization Translation P↝ P': • unwinding, inlining • thread T↝ function T' • main driver: • for round in [1..K] • for thread in [1..N] • T'thread (); T' skip resume exec context-switchpi Thread T↝ function T' • var x;↝ staticvar x; • stmt;↝ guard; stmt; skip ... ... Threadsimulation: round i • guesscontext-switchpointpi • executestmts from pi-1to pi • jump in mult. hops to the end simulation round i >1

  8. Lazy-CSeq rounds unwind backend sequential non-deterministic C program concurrent C program true/false sequential BMC CBMC, ESBMC, LLBMC CSeq P P'

  9. Conclusions Lightweight translation • small BMC formulae for small number of rounds • reduced memory footprint and verification times Backend integration • we support: BLITZ, CBMC, ESBMC, LLBMC as backends • extends any sequential verification tool for C programs • inherits all non-concurrency checks from the backend (e.g. dynamic memory allocation, array bounds checks, …) Effective for bug-hunting • many concurrency errors show up within few context-switches

  10. Thank You users.ecs.soton.ac.uk/gp4/cseq/cseq.html

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