Real-World Loops Are Easy to Predict

Rodrigues, Raphael Ernani

doi:10.1007/978-3-319-11863-5_9

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…In our experiments, Loopus is able to quicky conclude for termination in many cases since simple arguments are very often sufficient to prove that a given loop terminates Rodrigues et al [2014].…”

Section: Discussionmentioning

confidence: 99%

Synthesis of ranking functions using extremal counterexamples

GonnordLaure¹,

MonniauxDavid²,

RadanneGabriel³

2015

SIGPLAN Not.

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We present a complete method for synthesizing lexicographic linear ranking functions (and thus proving termination), supported by inductive invariants, in the case where the transition relation of the program includes disjunctions and existentials (large block encoding of control flow). Previous work would either synthesize a ranking function at every basic block head, not just loop headers, which reduces the scope of programs that may be proved to be terminating, or expand large block transitions including tests into (exponentially many) elementary transitions, prior to computing the ranking function, resulting in a very large global constraint system. In contrast, our algorithm incrementally refines a global linear constraint system according to extremal counterexamples: only constraints that exclude spurious solutions are included. Experiments with our tool Termite show marked performance and scalability improvements compared to other systems.

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Section: Discussionmentioning

confidence: 99%

Synthesis of ranking functions using extremal counterexamples

GonnordLaure¹,

MonniauxDavid²,

RadanneGabriel³

2015

SIGPLAN Not.

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“…Some of the non-separable loops in C++ applications are caused by the programming language's specified requirement for zero initialization of arrays, where each element is zero-initialized. It is also known that some of the C++ applications in the SPEC CPU2006 suite contain a large number of non-natural and multi-exit loops [42], which defeat LLVM's static analysis. We have also observed that LLVM's ability to disambiguate accesses to fields and members in structures (and classes) is limited, e.g.…”

Section: Discussionmentioning

confidence: 99%

Generalized profile-guided iterator recognition

Manilov

Vasiladiotis

Franke

2018

Proceedings of the 27th International Conference on Compiler Construction

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Iterators prescribe the traversal of data structures and determine loop termination, and many loop analyses and transformations require their exact identification. While recognition of iterators is a straight-forward task for affine loops, the situation is different for loops iterating over dynamic data structures or involving control flow dependent computations to determine the next data element. In this paper we propose a compiler analysis for recognizing loop iterators code for a wide class of loops. We initially develop a static analysis, which is then enhanced with profiling information to support speculative code optimizations. We have prototyped our analysis in the LLVM framework and demonstrate its capabilities using the SPEC CPU2006 benchmarks. Our approach is applicable to all loops and we show that we can recognize iterators in, on average, 88.1% of over 75,000 loops using static analysis alone, and up to 94.9% using additional profiling information. Existing techniques perform substantially worse, especially for C and C++ applications, and cover only 35-44% of the loops. Our analysis enables advanced loop optimizations such as decoupled software pipelining, commutativity analysis and source code rejuvenation for real-world applications, which escape analysis and transformation if loop iterators are not recognized accurately.

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Improving energy-efficiency by recommending Java collections

Oliveira

Castor

et al. 2021

Empir Software Eng

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Real-World Loops Are Easy to Predict

Cited by 3 publications

References 17 publications

Synthesis of ranking functions using extremal counterexamples

Synthesis of ranking functions using extremal counterexamples

Generalized profile-guided iterator recognition

Improving energy-efficiency by recommending Java collections

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