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Publications

Publications by HASLab

2022

Framing Program Repair as Code Completion

Authors
Ribeiro, F; Abreu, R; Saraiva, J;

Publication
INTERNATIONAL WORKSHOP ON AUTOMATED PROGRAM REPAIR (APR 2022)

Abstract
Many techniques have contributed to the advancement of automated program repair, such as: generate and validate approaches, constraint-based solvers and even neural machine translation. Simultaneously, artificial intelligence has allowed the creation of general-purpose pre-trained models that support several downstream tasks. In this paper, we describe a technique that takes advantage of a generative model - CodeGPT - to automatically repair buggy programs by making use of its code completion capabilities. We also elaborate on where to perform code completion in a buggy line and how we circumvent the open-ended nature of code generation to appropriately fit the new code in the original program. Furthermore, we validate our approach on the ManySStuBs4j dataset containing real-world open-source projects and show that our tool is able to fix 1739 programs out of 6415 - a 27% repair rate. The repaired programs range from single-line changes to multiple line modifications. In fact, our technique is able to fix programs which were missing relatively complex expressions prior to being analyzed. In the end, we present case studies that showcase different scenarios our technique was able to handle.

2022

WebAssembly versus JavaScript: Energy and Runtime Performance

Authors
De Macedo, J; Abreu, R; Pereira, R; Saraiva, J;

Publication
2022 INTERNATIONAL CONFERENCE ON ICT FOR SUSTAINABILITY (ICT4S 2022)

Abstract
The worldwide Web has dramatically evolved in recent years. Web pages are dynamic, expressed by programs written in common programming languages given rise to sophisticated Web applications. Thus, Web browsers are almost operating systems, having to interpret/compile such programs and execute them. Although JavaScript is widely used to express dynamic Web pages, it has several shortcomings and performance inefficiencies. To overcome such limitations, major IT powerhouses are developing a new portable and size/load efficient language: WebAssembly. In this paper, we conduct the first systematic study on the energy and run-time performance of WebAssembly and JavaScript on the Web. We used micro-benchmarks and also real applications in order to have more realistic results. Preliminary results show that WebAssembly, while still in its infancy, is starting to already outperform JavaScript, with much more room to grow. A statistical analysis indicates that WebAssembly produces significant performance differences compared to JavaScript. However, these differences differ between micro-benchmarks and real-world benchmarks. Our results also show that WebAssembly improved energy efficiency by 30%, on average, and showed how different WebAssembly behaviour is among three popular Web Browsers: Google Chrome, Microsoft Edge, and Mozilla Firefox. Our findings indicate that WebAssembly is faster than JavaScript and even more energy-efficient. Additionally, our benchmarking framework is also available to allow further research and replication.

2022

Energy Efficiency of Web Browsers in the Android Ecosystem

Authors
Gonçalves, N; Rua, R; Cunha, J; Pereira, R; Saraiva, J;

Publication
CoRR

Abstract

2022

Energy Efficiency of Python Machine Learning Frameworks

Authors
Ajel, S; Ribeiro, F; Ejbali, R; Saraiva, J;

Publication
Intelligent Systems Design and Applications - 22nd International Conference on Intelligent Systems Design and Applications (ISDA 2022) Held December 12-14, 2022 - Volume 2

Abstract

2022

E-MANAFA: Energy Monitoring and ANAlysis tool For Android

Authors
Rua, R; Saraiva, J;

Publication
PROCEEDINGS OF THE 37TH IEEE/ACM INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING, ASE 2022

Abstract
This article introduces the E-MANAFA energy profiler, a plug-and-play, device-independent, model-based profiler capable of obtaining fine-grained energy measurements on Android devices. Besides having the capability to calculate performance metrics such as the energy consumed and runtime during a time interval, E-MANAFA also allows to estimate the energy consumed by each device component (e.g. CPU, WI-FI, screen). In this article, we present the main elements that compose this framework, as well as its workflow. In order to present the power of this tool, we demonstrate how the tool can measure the overhead of the instrumentation technique used in the PyAnaDroid application benchmarking pipeline, which already supports E-MANAFA to monitor power consumption in its Android application automatic execution process. Video demo: shorturl.at/hmyz5

2022

A formal treatment of the role of verified compilers in secure computation

Authors
Almeida, JCB; Barbosa, M; Barthe, G; Pacheco, H; Pereira, V; Portela, B;

Publication
JOURNAL OF LOGICAL AND ALGEBRAIC METHODS IN PROGRAMMING

Abstract
Secure multiparty computation (SMC) allows for complex computations over encrypted data. Privacy concerns for cloud applications makes this a highly desired technology and recent performance improvements show that it is practical. To make SMC accessible to non-experts and empower its use in varied applications, many domain-specific compilers are being proposed.We review the role of these compilers and provide a formal treatment of the core steps that they perform to bridge the abstraction gap between high-level ideal specifications and efficient SMC protocols. Our abstract framework bridges this secure compilation problem across two dimensions: 1) language-based source- to target-level semantic and efficiency gaps, and 2) cryptographic ideal- to real-world security gaps. We link the former to the setting of certified compilation, paving the way to leverage long-run efforts such as CompCert in future SMC compilers. Security is framed in the standard cryptographic sense. Our results are supported by a machine-checked formalisation carried out in EasyCrypt.

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