Array dataflow analysis for polyhedral X10 programs

Yuki, Tomofumi; Feautrier, Paul; Rajopadhye, Sanjay; Saraswat, Vijay

doi:10.1145/2442516.2442520

Cited by 20 publications

(30 citation statements)

References 31 publications

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“…However, even for non-safetycritical systems, nondeterminacy is undesirable, as it makes testing and functional validation more difficult. To address this, tools and methods for determinacy analysis have been proposed recently for different concurrent programming domains [Vechev et al 2010;Leung et al 2012;Yuki et al 2013;Kuper et al 2014]. …”

Section: Introductionmentioning

confidence: 99%

Sequentially Constructive Concurrency—A Conservative Extension of the Synchronous Model of Computation

Hanxleden

Mendler

Aguado

et al. 2014

ACM Trans. Embed. Comput. Syst.

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Synchronous languages ensure determinate concurrency but at the price of restrictions on what programs are considered valid, or constructive. Meanwhile, sequential languages such as C and Java offer an intuitive, familiar programming paradigm but provide no guarantees with regard to determinate concurrency. The sequentially constructive (SC) model of computation (MoC) presented here harnesses the synchronous execution model to achieve determinate concurrency while taking advantage of familiar, convenient programming paradigms from sequential languages.In essence, the SC MoC extends the classical synchronous MoC by allowing variables to be read and written in any order and multiple times, as long as the sequentiality expressed in the program provides sufficient scheduling information to rule out race conditions. This allows to use programming patterns familiar from sequential programming, such as testing and later setting the value of a variable, which are forbidden in the standard synchronous MoC. The SC MoC is a conservative extension in that programs considered constructive in the common synchronous MoC are also SC and retain the same semantics. In this article, we investigate classes of shared variable accesses, define SC-admissible scheduling as a restriction of "free scheduling," derive the concept of sequential constructiveness, and present a priority-based scheduling algorithm for analyzing and compiling SC programs efficiently.

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Section: Introductionmentioning

confidence: 99%

Sequentially Constructive Concurrency—A Conservative Extension of the Synchronous Model of Computation

Hanxleden

Mendler

Aguado

et al. 2014

ACM Trans. Embed. Comput. Syst.

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show abstract

“…We think that the resilient equational theory opens the way to the development of laws that can be used in the X10 compiler to optimize programs, e.g. using polyhedral analysis [24]. We also plan for future work the extension of the framework we presented to cover the atomic and when constructs from X10.…”

Section: Discussionmentioning

confidence: 99%

“…it appears under an evaluation context, before s 2 . We refer to [24] for a static definition of the happens before relation in terms of static statements, which is also proved to be equivalent to a dynamic characterization that correspond to the following one. Definition 4.9 (Happens Before).…”

Section: Proposition 47 (Remote Computation) Let Bementioning

confidence: 99%

“…[17] presents an operational semantics for the X10 finish/async fragment, but again with a complex representation of control. We build on the work of [24] which for the first time represents the control state as a statement, and presents a very simple definition of the Happens Before relation. We extend that work to handle exceptions (necessary for the formalization of resilience), and place-shifting at, and formally treat resilience.…”

Section: Introductionmentioning

confidence: 99%

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Semantics of (Resilient) X10

Crafa

Cunningham

Saraswat

et al. 2014

ECOOP 2014 – Object-Oriented Programming

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We present a formal small-step structural operational semantics for a large fragment of X10, unifying past work. The fragment covers multiple places, mutable objects on the heap, sequencing, try/catch, async, finish, and at constructs. This model accurately captures the behavior of a large class of concurrent, multi-place X10 programs. Further, we introduce a formal model of resilience in X10. During execution of an X10 program, a place may fail for many reasons. Resilient X10 permits the program to continue executing, losing the data at the failed place, and most of the control state, and repairing the global control state in such a way that key semantic principles hold, the Invariant Happens Before Principle, and the Failure Masking Principle. These principles permit an X10 programmer to write clean code that continues to work in the presence of place failure. The given semantics have additionally been mechanized in Coq.

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“…This indicates non-determinism. In [8], polyhedral dataflow analysis was applied to the X10 language, using techniques similar to Bill Pugh's. The result was a tool able to detect some non-determinism at compile time.…”

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confidence: 99%

Author retrospective for array expansion, array shrinking, or there and back again

Feautrier

2014

25th Anniversary International Conference on Supercomputing Anniversary Volume -

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In the late 1980's, I was recovering from a long stint as the manager of Paris University computing facility (yes, there were still computing facilities, and PCs were just coming of age) and I was teaching old fashioned automatic parallelization to postgraduate students. I had heard of scalar expansion and privatization, and it was a natural question whether it could be extended to arrays. I first concocted partial solutions -for instance, valid only for the innermost loop -and then decided to try for the general case: converting array accesses to single assignment form. I soon realized that this implied finding the source, or last write before a given read, and that the solution must be a function of the position of the read in the temporal execution of the program. It was obvious that this could not be done for arbitrary complex programs, hence I specified a set of restriction: the polyhedral model. I also introduced the execution order, now known as the "happens-before" relation. Finding the last write then became an integer programming problem with some unfamiliar features: lexicographic order took the place of the economic function, the problem had to be solved exactly, and the coordinates of the read operation were acting as parameters. Hence,

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Array dataflow analysis for polyhedral X10 programs

Cited by 20 publications

References 31 publications

Sequentially Constructive Concurrency—A Conservative Extension of the Synchronous Model of Computation

Sequentially Constructive Concurrency—A Conservative Extension of the Synchronous Model of Computation

Semantics of (Resilient) X10

Author retrospective for array expansion, array shrinking, or there and back again

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