1. Lazy-CSeq A Lazy Sequentialization Tool for C Omar Inverso University of Southampton, UK Ermenegildo Tomasco University of Southampton, UK Bernd Fischer Stellenbosch University, South Africa Salvatore La Torre Università di Salerno, Italy Gennaro Parlato University of Southampton, UK

2. CSeq framework sequential non-deterministic C program P'P' concurrent C program P sequential analysis tool CSeq problem: analysis of concurrent programs approach: reduction to sequential analysis convert concurrent program P into sequential program P' analyse P' using a sequential tool

3. CSeq framework sequential non-deterministic C program P'P' concurrent C program P sequential analysis tool CSeq sequentialisation s Lal-Reps Memory-Unwinding Lazy-CSeq … unrolling inlining refactoring … problem: analysis of concurrent programs approach: reduction to sequential analysis convert concurrent program P into sequential program P' analyse P' using a sequential tool

4. CSeq framework sequential non-deterministic C program P'P' concurrent C program P sequential analysis tool CSeq testing Klee bounded model-checkers BLITZ CBMC ESBMC LLBMC … abstraction CPAchecker SATABS problem: analysis of concurrent programs approach: reduction to sequential analysis convert concurrent program P into sequential program P' analyse P' using a sequential tool

5. Lazy-CSeq sequential non-deterministic C program P'P' concurrent C program P Lazy-CSeq BMC tool round bound k P' equivalent to P up to k round-robin schedules

6. Lazy-CSeq sequential non-deterministic C program P'P' concurrent C program P Lazy-CSeq program unfolding context bounding BMC tool round bound k [CAV’14] P' equivalent to P up to k round-robin schedules

7. Lazy-CSeq sequential non-deterministic C program P'P' concurrent C program P Lazy-CSeq program unfolding context bounding CBMC BMC tool round bound k [CAV’14] P' equivalent to P up to k round-robin schedules

8. Lazy-CSeq P' equivalent to P up to k round-robin schedules sequential non-deterministic C program P'P' concurrent C program P Lazy-CSeq program unfolding context bounding CBMC BMC tool round bound k [CAV’14] improvements on SV-COMP’14 version optimised sequentialisation (less non-determinism, vars, clauses) improved backend support (CPROVER_bitvector, …)

9. Analyse each test case up to 5 times (with increasing bounds) ERROR found  UNSAFE no ERROR found  increase bounds, restart analysis no ERROR found, last phase  SAFE Competition

10. Analyse each test case up to 5 times (with increasing bounds) ERROR found  UNSAFE no ERROR found  increase bounds, restart analysis no ERROR found, last phase  SAFE Performance no missed bugs no false positives low verification time low memory consumption Competition

11. Thank You users.ecs.soton.ac.uk/gp4/cseq