Dynamic Verification of C11 Concurrency over Multi Copy Atomics

Singh, Sandeep; Sharma, Divyanjali; Sharma, Subodh

doi:10.1109/tase52547.2021.00023

Cited by 3 publications

(3 citation statements)

References 23 publications

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“…CDSChecker supports the C11 semantics. Most other techniques are designed for a variant [15] or subset [1,3,22] of C11 . 2.…”

Section: Implementation and Resultsmentioning

confidence: 99%

“…We collected a set of 1389 litmus tests of buggy C11 input programs (borrowed from Tracer [3]) to validate the correctness of FenSying and fFenSying experimentally. We study the performance of FenSying and fFenSying on a set of benchmarks borrowed from previous works on model checking under the C11 memory model and its variants [1,3,20,22]. Experimental validation.…”

Section: Implementation and Resultsmentioning

confidence: 99%

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Fence Synthesis under the C11 Memory Model

Singh¹,

Sharma²,

Jaju³

et al. 2022

Preprint

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The C/C++11 (C11 ) standard offers a spectrum of ordering guarantees on memory access operations. The combinations of such orderings pose a challenge in developing correct and efficient weak memory programs. A common solution to preclude those program outcomes that violate the correctness specification is using C11 synchronization-fences, which establish ordering on program events. The challenge is in choosing a combination of fences that (i) restores the correctness of the input program, with (ii) as little impact on efficiency as possible (i.e., the smallest set of weakest fences). This problem is the optimal fence synthesis problem and is NP-hard for straight-line programs. In this work, we propose the first fence synthesis technique for C11 programs called FenSying and show its optimality. We additionally propose a near-optimal efficient alternative called fFenSying. We prove the optimality of FenSying and the soundness of fFenSying and present an implementation of both techniques. Finally, we contrast the performance of the two techniques and empirically demonstrate fFenSying's effectiveness.

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“…CDSChecker supports the C11 semantics. Most other techniques are designed for a variant [15] or subset [1,3,22] of C11 . 2.…”

Section: Implementation and Resultsmentioning

confidence: 99%

Section: Implementation and Resultsmentioning

confidence: 99%

Fence Synthesis under the C11 Memory Model

Singh¹,

Sharma²,

Jaju³

et al. 2022

Preprint

Self Cite

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“…We straightforwardly encoded the definition of the C memory model (Model 2.6) in the model checker and used it on the examples in this paper as well as those provided by the Cerberus project [21]. The framework has provided the basis for other analyses involving security [15,73,78] and automated techniques [16,71]…”

Section: Related Workmentioning

confidence: 99%

Separation of concerning things: a simpler basis for defining and programming with the C/C++ memory model (extended version)

Colvin¹

2022

Preprint

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The C/C++ memory model provides an interface and execution model for programmers of concurrent (sharedvariable) code. It provides a range of mechanisms that abstract from underlying hardware memory modelsthat govern how multicore architectures handle concurrent accesses to main memory -as well as abstracting from compiler transformations. The C standard describes the memory model in terms of cross-thread relationships between events, and has been influenced by several research works that are similarly based. In this paper we provide a thread-local definition of the fundamental principles of the C memory model, which, for concise concurrent code, serves as a basis for relatively straightforward reasoning about the effects of the C ordering mechanisms. We argue that this definition is more practical from a programming perspective and is amenable to analysis by already established techniques for concurrent code. The key aspect is that the memory model definition is separate to other considerations of a rich programming language such as C, in particular, expression evaluation and optimisations, though we show how to reason about those considerations in the presence of C concurrency. A major simplification of our framework compared to the description in the C standard and related work in the literature is separating out considerations around the "lack of multicopy atomicity", a concept that is in any case irrelevant to developers of code for x86, Arm, RISC-V or SPARC architectures. We show how the framework is convenient for reasoning about well-structured code, and for formally addressing unintuitive behaviours such as "out-of-thin-air" writes.

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