Synthesis of loop-free programs

Gulwani, Sumit; Jha, Susmit; Tiwari, Ashish; Venkatesan, Ramarathnam

doi:10.1145/1993498.1993506

Cited by 229 publications

(176 citation statements)

References 35 publications

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“…Componentbased synthesis has been successfully applied to a wide variety of domains including bit-vector algorithms [9], string transformations [24], peephole optimizations [5], type convertors [21,27], deobfuscation [13], and geometry constructions [10].…”

Section: Related Workmentioning

confidence: 99%

Test-driven synthesis

Perelman

Gulwani

Grossman

et al. 2014

Proceedings of the 35th ACM SIGPLAN Conference on Programming Language Design and Implementation

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Programming-by-example technologies empower end-users to create simple programs merely by providing input/output examples. Existing systems are designed around solvers specialized for a specific set of data types or domain-specific language (DSL). We present a program synthesizer which can be parameterized by an arbitrary DSL that may contain conditionals and loops and therefore is able to synthesize programs in any domain. In order to use our synthesizer, the user provides a sequence of increasingly sophisticated input/output examples along with an expert-written DSL definition. These two inputs correspond to the two key ideas that allow our synthesizer to work in arbitrary domains. First, we developed a novel iterative synthesis technique inspired by test-driven development-which also gives our technique the name of testdriven synthesis-where the input/output examples are consumed one at a time as the program is refined. Second, the DSL allows our system to take an efficient component-based approach to enumerating possible programs. We present applications of our synthesis methodology to end-user programming for transformations over strings, XML, and table layouts. We compare our synthesizer on these applications to state-of-the-art DSL-specific synthesizers as well to the general purpose synthesizer Sketch.

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Section: Related Workmentioning

confidence: 99%

Test-driven synthesis

Perelman

Gulwani

Grossman

et al. 2014

Proceedings of the 35th ACM SIGPLAN Conference on Programming Language Design and Implementation

Self Cite

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“…The new values, pi and Si, are then used in the recursive search call on line 14. As this naive search approach is computationally intractable for instruction sequences of length greater than four [12,16,23] we introduce several optimizations below.…”

Section: Candidate Program Searchmentioning

confidence: 99%

From relational verification to SIMD loop synthesis

Barthe

Crespo

Gulwani

et al. 2013

Proceedings of the 18th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming

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Existing pattern-based compiler technology is unable to effectively exploit the full potential of SIMD architectures. We present a new program synthesis based technique for auto-vectorizing performance critical innermost loops. Our synthesis technique is applicable to a wide range of loops, consistently produces performant SIMD code, and generates correctness proofs for the output code. The synthesis technique, which leverages existing work on relational verification methods, is a novel combination of deductive loop restructuring, synthesis condition generation and a new inductive synthesis algorithm for producing loop-free code fragments. The inductive synthesis algorithm wraps an optimized depth-first exploration of code sequences inside a CEGIS loop. Our technique is able to quickly produce SIMD implementations (up to 9 instructions in 0.12 seconds) for a wide range of fundamental looping structures. The resulting SIMD implementations outperform the original loops by 2.0×-3.7×.Motivating Example. Consider the program fragment in Figure 1, which consists of a loop that traverses an array of widget structs (of length len). The loop body checks if the values in the tag and score fields satisfy certain properties and if so returns 1 immediately. If no such widget is found then 0 is returned.

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“…The problem of inferring expressions consistent with concrete and symbolic snippets can be viewed as an instance of the counterexample-guided inductive synthesis (CEGIS) strategy [8,13,23]. As mentioned earlier, the problem is analogous to solving an ∃∀ formula.…”

Section: Related Workmentioning

confidence: 99%

“…As mentioned earlier, the problem is analogous to solving an ∃∀ formula. The solutions described in prior work [8,13] explicitly encoded the problem into an SMT constraint, which was then solved using an SMT solver. The approach described in this work uses an enumerative technique to handle the existential quantifier and uses an SMT solver to check for universality.…”

Section: Related Workmentioning

confidence: 99%

“…Our solution is a variant of the counterexample-guided inductive synthesis (CEGIS) approach [8,13,23], and involves an interplay between pruning based on concrete examples and concretization of symbolic examples using an SMT solver. Specifically, our implementation enumerates expressions of increasing sizes, where the space of expressions is pruned significantly by considering two expressions equivalent if they evaluate to the same values for the given concrete examples.…”

Section: Introductionmentioning

confidence: 99%

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Transit

et al. 2013

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With the maturing of technology for model checking and constraint solving, there is an emerging opportunity to develop programming tools that can transform the way systems are specified. In this paper, we propose a new way to program distributed protocols using concolic snippets. Concolic snippets are sample execution fragments that contain both concrete and symbolic values. The proposed approach allows the programmer to describe the desired system partially using the traditional model of communicating extended finite-state-machines (EFSM), along with high-level invariants and concrete execution fragments. Our synthesis engine completes an EFSM skeleton by inferring guards and updates from the given fragments which is then automatically analyzed using a model checker with respect to the desired invariants. The counterexamples produced by the model checker can then be used by the programmer to add new concrete execution fragments that describe the correct behavior in the specific scenario corresponding to the counterexample.We describe TRANSIT, a language and prototype implementation of the proposed specification methodology for distributed protocols. Experimental evaluations of TRANSIT to specify cache coherence protocols show that (1) the algorithm for expression inference from concolic snippets can synthesize expressions of size 15 involving typical operators over commonly occurring types, (2) for a classical directory-based protocol, TRANSIT automatically generates, in a few seconds, a complete implementation from a specification consisting of the EFSM structure and a few concrete examples for every transition, and (3) a published partial description of the SGI Origin cache coherence protocol maps directly to symbolic examples and leads to a complete implementation in a few iterations, with the programmer correcting counterexamples resulting from underspecified transitions by adding concrete examples in each iteration.

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Synthesis of loop-free programs

Cited by 229 publications

References 35 publications

Test-driven synthesis

Test-driven synthesis

From relational verification to SIMD loop synthesis

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