Object serialization is critical in Java, which preserves objects in memory and transfers them among software systems if needed. However, the serialization techniques of modern Java systems are usually inflexible and inefficient under heavy serialization workloads, as they rely on manually-defined object schemas or omni-functional serializers. To tackle the above problem, we reveal a novel, serialization-specific optimization opportunity in Java. Based on it, we develop JOSer (Just-in-time Object SERializer), an efficient, Just-in-Time (JIT) object serialization technique. At runtime, JOSer generates a set of class-specific, JIT-friendly object serializers (i.e., serialization code), and then continuously optimizes them with the JIT compiler of Java Virtual Machine (JVM). JOSer also shares the metadata of objects under serialization and the serializers under optimization. We evaluate JOSer against six Java serialization techniques including OpenJDK's built-in serialization technique. Overall, JOSer improves the throughput by up to 20~83× in serialization and 43~229× in deserialization. JOSer has been successfully deployed in real-world products, reducing serialization CPU usage of Flink by 35.32~41.14% and latency of search recommendations by 30+ ms. JOSer grounds Apache Fory#8482;, an open-source serialization framework available at https://fory.apache.org/.

Simulink is MathWorks’ commercial cyber-physical systems development tool, which enables engineers to do rapid prototyping of their systems through simulation and embedded code generation. When a Simulink model meets requirements, engineers can utilize embedded coder to convert it into embedded code (e.g., C source code) and deploy it in safety-critical applications such as automotive, aerospace, and healthcare. However, bugs or incorrect implementations in code generation may lead to unexpected behaviors in target applications, posing security risks. Therefore, it is crucial to eliminate such bugs in embedded code generation. To address this issue, we propose DESCO, a differential testing approach to test embedded code generation in Simulink. DESCO considers the functional correlation between Simulink blocks for partitioning, aiming to generate diverse and complex bug-triggering Simulink models to thoroughly exercise the embedded code generation. DESCO then detects bugs by analyzing the outputs of these Simulink models by differential testing. The experiments demonstrate that DESCO significantly outperforms existing approaches. In three months, DESCO reported 16 issues, including 12 confirmed as bugs by MathWorks Support.

In software engineering, empirical studies on automated fault localization (FL) methods mainly focus on general software, and substantial progress has been made. However, the applicability and efficacy of these methods in specialized, domain-specific software like industrial software remains under-explored. Such specialized software is usually characterized by complex inputs and iterative computing paradigms, which could significantly influence the effectiveness of existing FL methods. To address this gap, this study takes a typical categorical of industrial software (i.e., computer-aided engineering (CAE) projects) as a case study, to investigate the feasibility and effectiveness of state-of-the-art FL methods within CAE projects. Through the reproduction of 76 real-world bugs from three widely used CAE projects (i.e., FDS, deal.II, and MFEM), we find that even the most precise FL methods require developers to examine on average 467.18 statements before finding bugs and can take 208.13 hours to execute. The complex inputs and long-term computation characteristics of CAE projects further increase the difficulty of FL. Moreover, FL on CAE also faces challenges, such as insufficient differentiation of coverage information and missing CAE-specific FL features. Based on our findings, we improve FL on CAE projects by proposing a set of CAE main module-based features, which improve the best-performed FL method in this study (i.e., DeepFL) by 35.93% and 45%, in terms of MAR and MFR , respectively.

Deep learning (DL) compilers are crucial for optimizing DL models across diverse hardware platforms, ensuring their reliability is paramount. Although many techniques have been developed to test DL compilers, existing methods often suffer from efficiency issues. To resolve this problem, this study proposes MeDAC, a novelMessage passing neural network based framework forDL compiler testingACceleration. The key insight of MeDAC is to construct a learning model to accurately predict the bug-revealing probabilities of test cases (i.e., DL models), allowing the test cases with higher bug-revealing probabilities to be executed. First, to construct the learning model, three types of features for DL models are extracted. Then, we propose a novel learning model based on the message passing neural network with an attention mechanism to accurately estimate the bug-revealing probabilities of DL models. Finally, MeDAC utilizes the learning model to predict the bug-revealing probability of each DL model, ensuring high-risk models are executed first. Experimental results on TVM and ONNXRuntime demonstrate that MeDAC achieves an average of 59.20% speedup in test execution time for DL compiler testing. Moreover, the peak performance improvements of MeDAC are 385.68% and 217.96% over the baseline approaches LET and GCN, respectively.

As integrated circuit scale grows and design complexity rises, effective circuit representation helps support logic synthesis, formal verification, and other automated processes in electronic design automation. And-Inverter Graphs (AIGs), as a compact and canonical structure, are widely adopted for representing Boolean logic in these workflows. However, the increasing complexity and integration density of modern circuits introduce structural heterogeneity and global logic information loss in AIGs, posing significant challenges to accurate circuit modeling. To address these issues, we propose FuncGNN, which integrates hybrid feature aggregation to extract multi-granularity topological patterns, thereby mitigating structural heterogeneity and enhancing logic circuit representations. FuncGNN further introduces gate-aware normalization that adapts to circuit-specific gate distributions, improving robustness to structural heterogeneity. Finally, FuncGNN employs multi-layer integration to merge intermediate features across layers, effectively synthesizing local and global semantic information for comprehensive logic representations. Experimental results on two logic-level analysis tasks (i.e., signal probability prediction and truth-table distance prediction) demonstrate that FuncGNN outperforms existing state-of-the-art methods, achieving improvements of 2.06% and 18.71%, respectively, while reducing training time by approximately 50.6% and GPU memory usage by about 32.8%. The code is available at https://github.com/Vandbs/FuncGNN .

Computer-aided engineering (CAE) tools are extensively used in safety-critical domains like aerospace design to simulate real-world physical processes on computers at reduced costs. However, CAE tools are prone to bugs, leading to incorrect simulation and serious design flaws. Existing testing methods have limited success in finding these bugs, since constructing test cases for CAE tools (known as CAE inputs) is challenging, due to the complexity of input parameter constraints and the differences of input syntax for each tool. Therefore, we propose NSGen, a template-based Numerical Simulation test caseGENerator for effective CAE input generation. To bridge input differences, NSGen designs general syntax rules that ignore semantic details of CAE inputs but retaining the format and validity of these inputs for different CAE tools. NSGen then designs semantic rules to define the parameters and their intricate constraints (i.e., dependency, exclusion, and extension). By instantiating these rules as templates, valid CAE inputs are generated using a syntax parser implemented by NSGen. Experiments show that NSGen can effectively generate CAE inputs with less than 0.33 second on average, triggering 6.28 to 10.55 times more potential issues than the baseline. Using these inputs, NSGen finds 12 bugs in popular CAE tools, including crash bugs and instability bugs.

Logic synthesis tools translate Hardware Description Language (HDL) designs into hardware implementation. To test these tools, numerous test cases are usually executed on the tools, yet only a few of them can trigger faults, leading to inefficient testing. Since executing test cases on logic synthesis tools often requires significant cost on complicated synthesis and simulation, fault-triggering test cases should be prioritized to execute. However, existing prioritization methods face challenges in accurately predicting the fault-triggering capability of dynamically generated test cases and modeling the unique syntactic and structure complexities of these HDL-based programs.Therefore, we propose ProFuse, a multi-dimensional feature fusion method for logic synthesis tool test case prioritization. ProFuse leverages Abstract Syntax Trees (AST) and Data Flow Graphs (DFG) to extract novel syntactic and structure features from HDL designs. These features are processed by a joint model of Multilayer Perceptron (MLP) and Graph Convolutional Network (GCN) to rank fault-triggering test cases accurately. ProFuse achieves an Average Percentage of Fault Detection (APFD) score of 0.9285, outperforming the state-of-the-art prioritization methods by 11.38% to 82.49%. ProFuse can efficiently rank randomly generated test cases to discover 15 new faults in logic synthesis tools (i.e., Yosys and Vivado). The Vivado community acknowledged our work for improving their tool.

Decompilation is one of the key techniques in software reverse engineering and is widely used in security-related tasks such as malware analysis and vulnerability detection. Software is typically released in binary form with symbol information stripped. Although decompilers are capable of reconstructing a lot of the information lost during compilation, they often fail to recover meaningful variable names. As a result, the readability of the decompiled code is significantly reduced, severely hindering the efficiency of reverse analysis. To address this problem, we propose a novel variable name recovery approach ReDevar for the decompiled code based on Multi-task Learning (MTL), which takes variable name recovery as the main task and introduces two additional tasks, including data source prediction and name complexity prediction, corresponding to two aspects of semantic understanding and semantic transformation of variables in the decompiled code. Data source prediction simulates the data flow relationship among variable instances, assisting ReDevar better understand the semantics of variables. The name complexity prediction task enables ReDevar to perceive the complexity of the expected variable name at a mask position, obtaining appropriate semantic transformation results. They are both jointly trained with the variable name recovery task to improve the understanding of ReDevar for variable semantics and name composition. We conducted a series of experiments to validate the effectiveness of ReDevar. Experimental results show that ReDevar achieves top- 1 accuracy of $54.44 \%$ on the VarCorpus benchmark dataset, 2.81% and 1.50% higher than the state-of-the-art approaches VarBERT and Resym respectively. In addition, we also evaluated the performance of ReDevar under various conditions, including different dataset splitting strategies, different decompilers, and different optimization levels. The results demonstrate that ReDevar generalizes well across all settings. Furthermore, the ablation study indicates that the two auxiliary tasks we introduced in ReDevar are both beneficial for the variable name recovery task.

The Uncertain Capacitated Arc Routing Problem (UCARP) presents unique challenges in real-world applications such as waste collection and winter gritting, where task demands and service costs are stochastic. Although Genetic Programming Hyper-Heuristics (GPHH) have demonstrated strong adaptability to such uncertainties by evolving dynamic routing policies, their complex decision-making processes hinder interpretability. To address this, a novel framework called Differential Evolution with Random Ablation (DERA) is introduced to generate diverse and feasible counterfactual explanations. Unlike traditional methods, DERA systematically explores multiple counterfactual scenarios by integrating random ablation into the optimisation process, thereby uncovering a broader range of plausible alternatives. Experimental results across various UCARP instances show that DERA consistently achieves high feasibility, minimal feature changes, and greater diversity in counterfactual explanations compared to baseline methods. This diversity enables a more comprehensive understanding of GPHH-evolved policies, providing actionable insights to improve decision-making transparency and robustness in dynamic environments.

MathWorks Simulink, a commercial CPS development tool chain, is widely used as an industry standard for designing and analyzing system behavior and generating embedded code for deployment. However, bugs in Simulink can cause unexpected behaviors during model compilation, making their elimination critical. Existing methods face two key challenges: generating equivalent models with varied data flows (data flow equivalence) and creating diverse block types to comprehensively test the compiler (mutation diversity). To address these, we propose LION, a differential testing approach. LION ensures data flow equivalence by inserting “store-revert” block pairs between existing blocks and tackles mutation diversity by employing Markov Chain Monte Carlo (MCMC) sampling to generate diverse new blocks. Differential testing is then used to identify bugs. Experiments show LION outperforms state-of-the-art approaches like SLforge, SLEMI, and COMBAT, detecting 610 additional compiler bugs in two weeks. Over two months, LION uncovered and reported 16 valid bugs in the widely used stable version of Simulink.

Abstract Researchers have recently achieved significant advances in deep learning techniques, which in turn has substantially advanced other research disciplines, such as natural language processing, image processing, speech recognition, and software engineering. Various deep learning techniques have been successfully employed to facilitate software engineering tasks, including code generation, software refactoring, and fault localization. Many studies have also been presented in top conferences and journals, demonstrating the applications of deep learning techniques in resolving various software engineering tasks. However, although several surveys have provided overall pictures of the application of deep learning techniques in software engineering, they focus more on learning techniques, that is, what kind of deep learning techniques are employed and how deep models are trained or fine-tuned for software engineering tasks. We still lack surveys explaining the advances of subareas in software engineering driven by deep learning techniques, as well as challenges and opportunities in each subarea. To this end, in this study, we present the first task-oriented survey on deep learning-based software engineering. It covers twelve major software engineering subareas significantly impacted by deep learning techniques. Such subareas spread out through the whole lifecycle of software development and maintenance, including requirements engineering, software development, testing, maintenance, and developer collaboration. As we believe that deep learning may provide an opportunity to revolutionize the whole discipline of software engineering, providing one survey covering as many subareas as possible in software engineering can help future research push forward the frontier of deep learning-based software engineering more systematically. For each of the selected subareas, we highlight the major advances achieved by applying deep learning techniques with pointers to the available datasets in such a subarea. We also discuss the challenges and opportunities concerning each of the surveyed software engineering subareas.

Electric vehicle charging stations (EVCSs) have become a pivotal infrastructure within the electric vehicle (EV) industry. In particular, many EV companies construct self-owned EVCSs to provide better charging service for their customers. For these self-owned EVCSs, to ensure the quality of service for self-owned users and third-party users, dynamic pricing based on the time-of-use (TOU) strategy has been extensively employed. This makes the demand forecasting of EVCSs important since it depicts the relationship between the charging price and the demand of an EVCS. Unfortunately, the existing techniques cannot accurately predict the demand of multiple users simultaneously. Consequently, this article examines the problem of multidemand forecasting of EVCSs, and proposes an efficient method to resolve this issue. The key insight of the proposed method is to train a deep neural network consisting of two subnetworks that can jointly forecast the demand of the self-owned user and the third-party user simultaneously. First, six kinds of features of EVCSs are extracted. Then, a novel deep neural network Atlas based on the attention mechanism is proposed to forecast the multidemand of EVCSs under the TOU strategy. Finally, to resolve the scarcity of historical charging demand data, a coarse-fine training process is proposed to train Atlas for each EVCS. The evaluation based on the real-world dataset of 771 EVCSs from an EV company demonstrates that Atlas significantly outperforms seven state-of-the-art techniques by up to 34.82%$\sim ~61.92$%.

In modern microarchitectures, machine-learning-based prefetchers use past memory requests to learn access patterns and predict memory addresses, thereby prefetching data into the cache to mitigate the processor-memory speed gap. However, they face two key challenges in capturing irregular access patterns generated by complex data structures and algorithms. One is data dispersion: the disorderliness of memory addresses makes it difficult for prefetchers to extract meaningful data features. The other is temporal and spatial complexity: existing prefetchers fail to effectively learn temporal and spatial characteristics, and thus are unable to explore more complex access patterns. To resolve these challenges, we propose TRACED, a novel temporal graph neural network-based prefetcher aimed at learning access patterns of memory addresses. TRACED consists of two key components: a dynamic clustering component and a temporal graph neural network component. In the dynamic clustering component, we introduce a similarity function to quantify the similarity of memory addresses. Based on the quantified similarity, we dynamically group unordered memory addresses into different clusters. This ensures that the memory addresses in each cluster are ordered and change smoothly, thus resolving the first challenge. The temporal graph neural network component constructs a spatiotemporal graph to represent relationships among memory addresses. This helps capture temporal and spatial characteristics both across and within clusters, thus resolving the second challenge. This article demonstrates the effectiveness of the proposed prefetcher through experiments. Specifically, in terms of accuracy, TRACED outperforms BO, SPP, DOMINO, Delta-LSTM, and VOYAGER by 2.29%–40.83% on average. Furthermore, TRACED attains remarkable coverage of 55.67% and IPC of 43.75%, outperforming all competing approaches in both metrics.

Field Programmable Gate Array (FPGA) logic synthesis compilers (e.g., Vivado, Iverilog, Yosys, and Quartus) are widely applied in Electronic Design Automation (EDA), such as the development of FPGA programs. However, defects (e.g. incorrect synthesis) in logic synthesis compilers may lead to unexpected behaviors in target applications, posing security risks. Therefore, it is crucial to thoroughly test logic synthesis compilers to eliminate such defects. Despite several Hardware Design Language (HDL) code generators (e.g., Verismith) having been proposed to find defects in logic synthesis compilers, the effectiveness of these generators is still limited by the simple code generation strategy and the monogeneity of the generated HDL code. This paper proposes EvoHDL, a novel method to generate syntax-valid HDL code for comprehensively testing FPGA logic synthesis compilers. EvoHDL can generate more complex and diverse defect-triggering HDL code (e.g., Verilog, VHDL, and SystemVerilog) by leveraging the guidance of abstract syntax tree and the extensive function block libraries of cyber-physical systems. Extensive experiments show that the diversity and defect-triggering capability of HDL code generated by EvoHDL are significantly better than the state-of-the-art method (i.e., Verismith). In three months, EvoHDL has reported 20 new defects–many of which are deep and important; 16 of them have been confirmed.

Field-Programmable Gate Array (FPGA) timing simulation is essential in electronic circuit design, allowing for the verification of timing characteristics like delays and clock frequencies. However, bugs in timing simulation tools can lead to inaccurate results, potentially causing designers to miss critical issues in chip performance. Traditional testing methods often fall short in thoroughly assessing these tools, as current FPGA testing primarily focuses on synthesis and behavioral simulation, neglecting timing aspects. To address this issue, we propose SIMTAM for testing timing simulation tools. Specifically, SIMTAM consists of three components: equivalent delay region construction, diversity program segment generation, and differential testing. Given a seed circuit design file written by hardware description language such as Verilog, the delay region construction component randomly identifies delay structures for inertial delay in the design file to construct equivalent delay sleep regions. In the sleep region, the simulator skips the signal pulse whose width is less than the specified delay, thus ensuring the equivalence of the variations. The diversity program segment generation component combines Verilog expressions using generation operators and injects them into the sleep region to generate diverse design files. The differential testing component compares the seed and variant design files to find compilation inconsistency issues. In 5 months, SIMTAM reported 16 bugs to developers in two popular timing simulation tools, Iverilog and Vivado, 10 of which are confirmed.

Online service systems struggle with accurately and quickly pinpointing and resolving failures within their intricate systems, and it therefore emerges the solutions for fault localization in the code. However, the previous fault localization models suffer from low localization accuracy and poor interpretability due to the complex dependencies among fault characteristics in industrial practice. To address this issue, challenges brought by the long-distance dependencies among fault features and the unbalanced distribution of fault knowledge, and to improve the interpretability of the model, we present a fault localization model in online service systems more actionable and interpretable, named FL-AIer. Specifically, FL-AIer consists of two components: the feature encoding component and the fault localization component. The feature encoding component utilizes graph attention networks to capture the complex spatio-temporal dependencies within fault features. Then, the fault localization component adopts a three-stage approach, leveraging a multi-attention mechanism to identify and prioritize the most relevant fault features for precise localization. Additionally, the Fault Knowledge Balancing module it contains introduces a weighted Kullback-Leibler divergence loss function to ensure that the model pays adequate attention to all fault features, addressing the issue of imbalanced fault knowledge distribution and enhancing localization performance. We conducted extensive experiments on four datasets, and the results demonstrated that FL-AIer effectively addressing the challenges of fault localization in online system environments, and consistently outperforms the state-of-the-art methods across various evaluation metrics such as A@1, A@2, A@3, A@5, and MAR. For instance, FL-AIer achieves significant improvements of 5.82%, 10.77%, 4.20%, and 15.56% on the A@1 metric, respectively. These results fully demonstrate the excellent effectiveness of FL-AIer in effectively addressing the challenges of fault localization in online system environments, surpassing the performance of existing state-of-the-art methods.

Automated software debugging plays a crucial role in aiding software developers to swiftly identify and attempt to rectify faults, thereby significantly reducing developers’ workload. Previous researches have predominantly relied on simplistic semantic deep learning or statistical analysis methods to locate faulty statements in diverse projects. However, code repositories often consist of lengthy sequences with long-distance dependencies, posing challenges for accurately modeling fault localization using these methods. In addition, the lack of joint reasoning among various faults prevents existing models from deeply capturing fault information. To address these challenges, we propose a method named CodeHealer to achieve accurate fault localization and program repair. CodeHealer comprises three components: a Deep Semantic Information Extraction Component that effectively extracts deep semantic features from suspicious code statements using classifiers based on Joint-attention mechanisms; a Suspicious Statement Ranking Component that combines various fault localization features and employs multilayer perceptrons to derive multidimensional vectors of suspicion values; and a Fault Repair Component that, based on ranked suspicious statements generated by fault localization, adopts a top-down approach using multiple classifiers based on Co-teaching mechanisms to select repair templates and generate patches. The experimental results indicate that when applied to fault localization, CodeHealer outperforms the best baseline method with improvements of 11.4%, 2.7%, and 1.6% on Top-1/3/5 metrics, respectively. It also reduces the MFR and MAR by 9.8% and 2.1%, where lower values denote better fault localization effectiveness. Additionally, in automated software debugging, CodeHealer fixes an additional 6 faults compared to the current best method, totaling 53 faults repaired.

FPGA (Field Programmable Gate Array) synthesis tools are crucial for hardware development and AI acceleration, and their bugs could compromise hardware reliability and risk downstream applications. However, it remains unknown in understanding the characteristics of these bugs. What are the root causes that trigger bugs in FPGA synthesis tools? What are the characteristics of these bugs? What are the challenges in detecting and addressing them? This paper takes the first step towards answering these questions by conducting a comprehensive study of FPGA synthesis tool bugs. We analyze 551 confirmed bugs in both commercial and open source FPGA synthesis tools, i.e., Vivado, Quartus Prime, and Yosys, covering root causes, symptoms, bug-prone components, fix characteristics, and achieve 17 valuable findings. We find that, on average, around 46.2% of bugs result from HDL (Hardware Description Language) standard noncompliance across the three tools. However, it is hard for current formal validations to fully test HDL standards compliance. Additionally, on average over 25.8% bugs show domain-specific optimization traits due to inappropriate optimization and mapping. Meanwhile, beyond 28% of bugs trigger unexpected behavior without clear signs, making the formulation of effective test oracles challenging. These findings help addressing FPGA synthesis tool bugs and guide further research.

Numerical simulation (NS) software is widely used in safety-critical domains (e.g., aerospace design) to simulate actual physical processes of real-world entities on computers. However, NS software is error-prone, whose bugs lead to incorrect simulation, and may even cause disastrous flaws in safety-critical applications. Although many studies investigate the bug characteristics of computation-centered software, such as machine learning systems, the characteristics of NS software bugs have not been fully studied: what are the root causes and symptoms; how are they different from other computation-centered software; and why the difference occurs. To bridge this gap, we present a systematic study of NS software bugs by analyzing 352 bugs in three popular NS projects (i.e., FDS, SU2, and Kratos) for different domains. We summarize seven root causes (with 18 subcategories) and five symptoms. We find that the correctness, completeness, compatibility, and parallelization to implement NS algorithms (i.e., models) are error-prone. Many root causes (e.g., incorrect model and incorrect initialization) require physical and chemical knowledge to avoid bugs, which may not be mastered by typical software developers. These findings motivate new challenges and opportunities for future NS software development, such as designing domain specific language systems for NS model.

High-level synthesis (HLS) tools have been widely used in field-programmable gate array (FPGA) design to convert C/C++ code to hardware description language code. Unfortunately, HLS tools are susceptible to bugs, which can introduce serious vulnerabilities in FPGA products, leading to substantial losses. However, the characteristics of these bugs (e.g., root causes and bug-prone stages) have never been systematically studied, which significantly hinders developers from effectively handling HLS tool bugs. To this end, we conduct the first empirical study to uncover HLS tool bug characteristics. We collect 349 bugs of a widely used HLS tool, namely Bambu. We study the root causes, buggy stages, and bug fixes of these bugs by applying a multiperson collaboration method. Finally, 13 valuable findings are summarized. We find 14 categories of root causes in Bambu bugs; most bugs (22.1%) are caused by incorrect implementation of IR processing; the front end of Bambu is more bug-prone; to fix these bugs, 2.27 files and 80.19 lines of code need to be modified on average. We also present the insights gained from 95 Vitis HLS bugs. From these findings, we suggest that developers could use an on-the-fly code generator configuration method to generate suitable testing programs for HLS tool bug detection and apply large language models to assist in fixing HLS tool bugs.

System bug identification plays a key role in autonomous vehicles for avoiding disastrous consequences. However, it is time consuming to fully test autonomous vehicles. Although some techniques have been proposed to improve testing efficiency, they struggle to handle the complex test scenarios because they cannot adequately represent the scenarios and efficiently assess the vulnerability-triggering potential of test scenarios. In this study, we propose Learning to accElerate Autonomous Systems Testing (LEAST), a graphic neural network (GNN)-based method to effectively accelerate autonomous driving system (ADS) testing. First, given a test scenario, LEAST extracts a series of scenes from the test scenario and constructs feature graphs from these scenes, which are helpful to characterize the test scenario. Then, we propose a GNN-based method to predict the risk value of each scene, indicating the likelihood of a vehicle encountering a traffic accident. Finally, LEAST prioritizes test scenarios based on the number of high-risk scenes in the scenarios, ensuring that scenarios more likely to trigger ADS bugs are executed earlier. Experiments onthree open-source ADSs show that LEAST significantly outperforms baseline test acceleration approaches by 10.13–15.34% in terms of average percentage of fault detected. When integrating LEAST into the advanced ADS testing approach DriveFuzz, LEAST successfully improves the testing efficiency by 39–67%.

With the extensive application of artificial intelligence (AI) technologies, automated programming language-natural language (PL-NL) systems have gained significant attention, driving a series of related tasks served for developers and users, such as code search and summarization. Currently, mainstream PL-NL systems regard PL-NL as bimodal data and utilize two individual neural architectures (e.g., recurrent neural network) to learn the representation of PL-NL and build their semantic relations, improving the effects of these tasks. However, there exist two issues that limit the ability of these service systems in representation learning: first, large vocabularies cause data sparsity problems and limit the learning ability of neural architectures; second, there is not always a one-to-one correspondence between source code and natural language. To address these two issues, in this article, we introduce the unified neural architecture (UNA) by building a unified vocabulary (Uni-Vocab) at the subword level, to provide high-quality PL-NL services. In the Uni-Vocab, we build a unified modal encoding for PL-NL, which allows us to effectively control the vocabulary size and solve the data sparsity problem. Afterward, our built UNA can learn the unified contextual representation of PL-NL, which helps build their unified semantic relations. To validate the effectiveness of the proposed UNA, we perform experiments on code search and code summarization, which are two PL-NL tasks for developers and users. Experimental results demonstrate UNA can obtain noteworthy performance improvement. In detail, the baseline approaches in these two tasks get improvements by up to 36.09% and 18.02% in terms of mean reciprocal rank and bilingual evaluation understudy, respectively.

In electronic design automation (EDA), printed circuit board (PCB) design plays a crucial role. Ensuring the reliability of the PCB design tool chain is essential, as bugs in the tool chain can cause significant issues and losses during design and production. To improve reliability, a key process is to generate numerous PCB schematics and execute them in the tool chain, to test the correctness of each tool chain functionality. However, it is a challenge to automatically generate valid schematics to simulate the actual use of the PCB design tool chain. To this end, we propose PCBSmith, an effective schematic generator for PCB design tool chain. PCBSmith mimics the steps of a PCB designer for schematic design. PCBSmith first selects the appropriate electronic components from a comprehensive library and connects them according to the constraints of different components. PCBSmith then sets electrical parameters and simulation models for each component, eventually generating simulatable schematics. Experiments show that PCBSmith demonstrates high efficiency in schematic generation, averaging only one schematic per second. PCBSmith maintains a success rate over 61.44% for generating schematics, which outperforms the baseline method by 30.68%. The generated schematics have successfully identified unknown bugs in PCB design tools.

Software developers and maintainers frequently conduct software refactorings to improve software quality. Identifying the conducted software refactorings may significantly facilitate the comprehension of software evolution, and thus facilitate software maintenance and evolution. Besides that, the identified refactorings are also valuable for data-driven approaches in software refactoring. To this end, researchers have proposed a few approaches to identifying software refactorings automatically. However, the performance (especially precision) of such approaches deserves substantial improvement. To this end, in this paper, we propose a novel refactoring detection approach, calledReExtractor+. At the heart ofReExtractor+is a reference-based entity matching algorithm that matches coarse-grained code entities (e.g., classes and methods) between two successive versions, and a context-aware statement matching algorithm that matches statements within a pair of matched methods. We evaluatedReExtractor+on a benchmark consisting of 400 commits from 20 real-world projects. The evaluation results suggested thatReExtractor+significantly outperformed the state of the art in refactoring detection, reducing the number of false positives by 57.4% and improving recall by 18.4%. We also evaluated the performance of the proposed matching algorithms that serve as the cornerstone of refactoring detection. The evaluation results suggested that the proposed algorithms excel in matching code entities, substantially reducing the number of mistakes (false positives plus false negatives) by 67% compared to the state-of-the-art approaches.

Compiler error recovery diagnostics facilitates software development as it provides the possible causes and suggestions on potential programming errors. However, due to compiler bugs, error recovery diagnostics could be erroneous, spurious, missing, or even crashing for mature production compilers like GCC and Clang. Compiler testing is one of the most widely used ways of ensuring its quality. However, existing compiler diagnostics testing approaches (e.g., DIPROM) only consider the typically syntactically valid test programs as inputs, which are unlikely to trigger compiler error recovery defects. Therefore, in this paper, we propose the first mutation based approach for Compiler Error Recovery diagnostics Testing, called CERTest. Specifically, CERTest first explores the mutation space for a given seed program, and leverages a series ofmutation configurations(which are referred as a series of mutators applying for a seed) to iteratively mutate the structures of the seed, so as to generate error-sensitive program variants for triggering compiler error recovery mechanisms. To effectively construct error-sensitive structures, CERTest then applies a novel furthest-first based selection approach to select a set of representative mutation configurations to generate program variants in each iteration. With the generated program variants, CERTest finally leverages differential testing to detect error recovery defects in different compilers. The experiments on GCC and Clang demonstrate that CERTest outperforms five state-of-the-art approaches (i.e., DIPROM,Ccoft,Clang-fuzzer, AFL++, and HiCOND) by up to 13.10%$\sim$221.61% on average in the term of bug-finding capability, and CERTest detects 9 new error recovery defects, 5 of which have been confirmed or fixed by developers.

Software defect prediction refers to the systematic analysis and review of software using various approaches and tools to identify potential defects or errors. Software defect prediction aids developers in swiftly identifying defects and optimizing development resource allocation, thus enhancing software quality and reliability. Previous defect prediction approaches still face two main limitations: 1) lacking of contextual semantic information and 2) Ignoring the joint reasoning between different granularities of defect predictions. In response to these challenges, we propose LineDef, a line-level defect prediction approach by capturing code contexts with graph convolutional networks. Specifically, LineDef comprises three components: the token embedding component, the graph extraction component, and the multi-granularity defect prediction component. The token embedding component maps each token to a vector to obtain a high-dimensional semantic feature representation of the token. Subsequently, the graph extraction component utilizes a sliding window to extract line-level and token-level graphs, addressing the challenge of capturing contextual semantic relationships in the code. Finally, the multi-granularity defect prediction component leverages graph convolutional layers and attention mechanisms to acquire prediction labels and risk scores, thereby achieving file-level and line-level defect prediction. Experimental studies on 32 datasets across 9 different software projects show that LineDef exhibits significantly enhanced balanced accuracy, ranging from 15.61% to 45.20%, compared to state-of-the-art file-level defect prediction approaches, and a remarkable cost-effectiveness improvement ranging from 15.32% to 278%, compared to state-of-the-art line-level defect prediction approaches. These results demonstrate that LineDef approach can extract more comprehensive information from lines of code for defect prediction.

Deep learning (DL) compilers, such as TVM and TensorFlow, encompass a variety of passes for optimizing computation graphs (i.e., DL models). Despite the efforts on developing optimization passes, it remains a challenge in arranging these passes - most compilers employ fixed pass sequences that do not fit with computation graphs of diverse structures; on the other hand, optimization passes have cascade effects, making the structures of graphs under compilation volatile and as well making it difficult to generate optimal sequences for graphs. Inspired by recent progresses on static computing memory footprints (i.e., memory usages) of computation graphs, we introduce in this paper OPASS, a novel approach to orchestrating TVM's optimization passes for lowering memory footprints of computation graphs, and finally allowing the graphs to run on memory-constrained devices. The key idea is, given a computation graph$G$, to optimize the graph heuristically and iteratively: OPASS learns the effects of passes on the graph; it then optimizes$G$iteratively - each iteration picks up a pass by the reduction of the memory footprint of$G$and as well the implicit effects of the pass for further optimizations, letting the pass be applied. We evaluate OPASS on Rebench (a suite of computation graphs) and two real-world models (Transformer and ResNet). The results clearly show the strength of OPASS: it outperforms TVM's default sequence by$1.77\times$in reducing graphs' memory footprints, with affordable costs; it also offers extra memory reductions of$5\sim 12\%$by catching the implicit effects of passes. Furthermore, OPASS helps analyze positive/negative effects of passes to graphs' memory footprints, providing TVM developers with best practices for designing optimization pass sequences.

The aim of Just-In-Time (JIT) defect prediction is to predict software changes that are prone to defects in a project in a timely manner, thereby improving the efficiency of software development and ensuring software quality. Identifying changes that introduce bugs is a critical task in just-in-time defect prediction, and researchers have introduced the SZZ approach and its variants to label these changes. However, it has been shown that different SZZ algorithms introduce noise to the dataset to a certain extent, which may reduce the predictive performance of the model. To address this limitation, we propose the Confident Learning Imbalance (CLI) model. The model identifies and excludes samples whose labels may be corrupted by estimating the joint distribution of noisy labels and true labels, and mitigates the impact of noisy data on the performance of the prediction model. The CLI consists of two components: identifying noisy data (Confident Learning Component) and generating a predicted probability matrix for imbalanced data (Imbalanced Data Probabilistic Prediction Component). The IDPP component generates precise predicted probabilities for each instance in the training set, while the CL component uses the generated predicted probability matrix and noise labels to clean up the noise and build a classification model. We evaluate the performance of our model through extensive experiments on a total of 126,526 changes from ten Apache open source projects, and the results show that our model outperforms the baseline methods.

With the emergence of smartphones, Android has become a widely used mobile operating system. However, it is vulnerable when encountering various types of attacks. Every day, new malware threatens the security of users’ devices and private data. Many methods have been proposed to classify malicious applications, utilizing static or dynamic analysis for classification. However, previous methods still suffer from unsatisfactory performance due to two challenges. First, they are unable to address the imbalanced data distribution problem, leading to poor performance for malware families with few members. Second, they are unable to address the zero-day malware (zero-day malware refers to malicious applications that exploit unknown vulnerabilities) classification problem. In this article, we introduce an innovative meta -learning approach for m ulti-family A ndroid m alware c lassification named Meta-MAMC , which uses meta-learning technology to learn meta-knowledge (i.e., the similarities and differences among different malware families) of few-family samples and combines new sampling algorithms to solve the above challenges. Meta-MAMC integrates (i) the meta-knowledge contained within the dataset to guide models in learning to identify unknown malware; and (ii) more accurate and diverse tasks based on novel sampling strategies, as well as directly adapting meta-learning to a new few-sample and zero-sample task to classify families. We have evaluated Meta-MAMC on two popular datasets and a corpus of real-world Android applications. The results demonstrate its efficacy in accurately classifying malicious applications belonging to certain malware families, even achieving 100% classification in some families.

Online chatrooms serve as vital platforms for information exchange among software developers. With multiple developers engaged in rapid communication and diverse conversation topics, the resulting chat messages often manifest complexity and lack structure. To enhance the efficiency of extracting information from chat threads , automatic mining techniques are introduced for thread classification. However, previous approaches still grapple with unsatisfactory classification accuracy due to two primary challenges that they struggle to adequately capture long-distance dependencies within chat threads and address the issue of category imbalance in labeled datasets. To surmount these challenges, we present a topic classification approach for chat information types named EAEChat. Specifically, EAEChat comprises three core components: the text feature encoding component captures contextual text features using a multi-head self-attention mechanism-based text feature encoder, and a siamese network is employed to mitigate overfitting caused by limited data; the data augmentation component expands a small number of categories in the training dataset using a technique tailored to developer chat messages, effectively tackling the challenge of imbalanced category distribution; the non-text feature encoding component employs a feature fusion model to integrate deep text features with manually extracted non-text features. Evaluation across three real-world projects demonstrates that EAEChat, respectively, achieves an average precision, recall, and F1-score of 0.653, 0.651, and 0.644, and it marks a significant 7.60% improvement over the state-of-the-art approaches. These findings confirm the effectiveness of our method in proficiently classifying developer chat messages in online chatrooms.

Familiar analysis for malware plays an important role in comprehending the diversity of malicious behaviors and identifying the emerging security threats. Existing studies mainly focus on classifying malware into known families by supervised learning. However, these methods face two main challenges, 1) the lack of a large amount of labeled data and 2) the poor effectiveness in identifying unknown families of malware. To overcome these challenges, we propose a new method called multiple features (MulFC) based on unsupervised learning. In the method, we first leverage a decompiling tool to extract multiple features, including manifest features, application programming interface (API) features, and opcode features. Then, the opcode features are preprocessed to filter out the redundant ones to reduce the calculation cost. After that, we adopt the Jaccard index to calculate the similarities between malware and construct a malware network. Finally, InfoMap is applied to perform the clustering on the basis of the malware network. Overall, MulFC does not require the use of labeled data and can identify unknown families of malware. Experiments are conducted on two datasets for the performance evaluation of MulFC. The experimental results show that MulFC achieves 0.810 in terms of normalized mutual information, 0.576 in terms of adjusted rand index, 0.620 in terms of the Fowlkes–Mallows index, and 0.805 in terms of V-measure on average, and outperforms the state-of-the-art baseline method by 0.060, 0.054, 0.038, and 0.065, respectively.

Simulink compiler testing is important since all cyber-physical system (CPS) models are required to be compiled by Simulink compiler. Current testing processes use CPS models generated by CPS model generators for testing. Since the effectiveness of CPS model generators heavily relies on suitable generator configurations, existing approaches randomize configurations or infer configurations with historical bug information to generate diverse bug-triggering CPS models. However, these approaches are designed for general-purpose compilers (e.g., GCC), which have two challenges when testing Simulink compiler, namely, the CPS model representation challenge on representing CPS models for diversity measurement and the configuration learning challenge on learning configurations to generate diverse CPS models. To address these challenges, we proposeReinforcement lEarning-basedCOnfiguRationDiversification (RECORD), a new configuration diversification approach. RECORD has a feature vectorization component, which addresses the first challenge by representing CPS models as feature vectors to capture the local and global characteristics of CPS models for diversity measurement. RECORD then uses a reinforcement learning component to generate diverse CPS models based on the learned relationship between configuration updates and diversity changes, thus addressing the second challenge. Experiments demonstrate that within three months, RECORD reported 11 confirmed Simulink compiler bugs, significantly outperforming the state-of-the-art configuration diversification approaches. RECORD can also facilitate different testing strategies to find more bugs.

Low-code development platforms (LCDPs) are increasingly being introduced and leveraged by major IT enterprises to lower the threshold and promote the efficiency of software development. Like other software systems, LCDPs are also inevitable to have bugs. The bugs in LCDPs may cause unpredictable consequences as they pose risks to all the downstream software products. However, to the best of our knowledge, there exist no studies that ever consider the bugs caused by LCDPs. To handle the LCDP bugs better, in this article, we conduct an empirical study of the characteristics of LCDP bugs by examining 974 confirmed bugs of four dominant LCDPs (i.e., OutSystems, Mendix, Appsmith, and Budibase) from both commercial and open-source domains. These bugs are analyzed from three perspectives, including bug root causes, bug symptoms, and the affected stages of LCDPs. Based on the analysis, we obtain a series of valuable findings. For example, around 60% of the bugs reside in the stage of designing and specifying the developed applications. Over 37% of the bugs lead LCDPs to behave unexpectedly but without showing explicit signs. Moreover, the bugs relevant to the incorrect graphics of user interfaces are significant due to the characteristics of LCDPs. These findings point out the guidelines, challenges, and future directions to address LCDP bugs.

Convolutional Neural Networks (CNNs) are widely deployed on the Graphics Processing Unit (GPU) to support Deep Learning (DL) based services. Popular DL frameworks usually ignore the inter-operator parallelism when executing the inference of CNNs, which results in high inference latency. Although some inter-operator scheduling methods have been proposed, there remains a critical trade-off issue between inference latency (effectiveness) and scheduling time (efficiency). In this article, we propose LIOS, a novel latency-based heuristic inter-operator scheduling method to balance inference latency and scheduling time. In LIOS, a CNN latency model is built based on the given CNN and GPU. Then every operator is assigned a priority value to represent its importance. During each iteration of the scheduling process, LIOS identifies the current data-independent operators, selects the operator with the highest priority value, and assigns it to the GPU stream with the smallest finish time. Extensive experimental results have demonstrated the effectiveness and efficiency of LIOS. For the effectiveness, LIOS can speed up the inference of normal-size and large-size CNNs by 1.13$\sim 1.59 \times$compared to sequential scheduling. This result is comparable to IOS, the latest state-of-the-art scheduling method. For the efficiency, LIOS can speed up the scheduling process by 7$\sim 9210\times$compared to IOS.

Automated software fault localization has become one of the hot spots on which researchers have focused in recent years. Existing studies have shown that learning-based techniques can effectively localize faults leveraging various information. However, there exist two problems in these techniques. The first is that they simply represent various information without caring the contribution of different information. The second is that the data imbalance problem is not considered in these techniques. Thus, their effectiveness is limited in practice. In this paper, we propose HetFL, a novel heterogeneous graph-based software fault localization technique to aggregate different information into a heterogeneous graph in which program entities and test cases are regarded as nodes, and coverage, change histories, and call relationships are viewed as edges. HetFL first extracts textual and structure information from source code as attributes of nodes and integrates them to form an attribute vector. Then, for a given node, HetFL finds its neighbor nodes based on the types of edges and aggregates corresponding neighbor nodes to form type vectors. After that, the attribute vector and all the type vectors of each node are aggregated to generate the final vector representation by an attention mechanism. Finally, we leverage a convolution neural network (CNN) to obtain the suspicious score of each method. To validate the effectiveness of HetFL, experiments are conducted on the widely used dataset Defects4J (v1.2.0). The experimental results show that HetFL can localize 217 faults within Top-1 that is 25 higher than the state-of-the-art technique DeepFL, and achieve 6.37 and 5.58 in terms of MAR and MFR which improve DeepFL by 9.0% and 5.6%, respectively. In addition, we also perform experiments on the latest version of Defects4J (v2.0.0). The experimental results show that HetFL has better performance than the baseline methods.

High-Level Synthesis (HLS) tools convert C/C++ design code into Hardware Description Language (HDL) code automatically, which are often used for Field Programmable Gate Array (FPGA) design. HLS tools provide many pragmas, which are a kind of directive to be inserted into C/C++ code, for designers to efficiently control the synthesis of code components (e.g., arrays and loops) to generate FPGA implementations with varying performances and costs. However, the use of some pragmas may trigger HLS tool bugs (e.g., tool crashes). Although many formal methods have been proposed to verify the correctness of various HLS phases, no relevant work addresses the problem on detecting HLS tool pragma-related bugs. To resolve this problem, two challenges need to be addressed, namely the selection of testing programs and the acquisition of pragma combinations, due to the enormous number of testing programs and pragma combinations. In this paper, we propose TEPACS, a TEsting Program and prAgma Combination Selection-based framework, to construct diverse testing programs with pragmas for effectively detecting HLS tool pragma-related bugs. TEPACS follows the idea of fuzzing, which is a widely used technique in software testing. First, TEPACS selects the representative testing program according to the cosine distance between the code component vectors of testing programs. Then, for a selected program, TEPACS generates its golden output and uses the pragma combination selection method based on combinatorial testing to generate a set of programs with different pragmas. TEPACS uses the HLS tool under test to convert these testing programs into HDL codes and obtains the simulation results of the HDL code. Finally, based on differential testing, TEPACS identifies HLS tool bugs triggered if the simulation result and golden output are inconsistent. We evaluate TEPACS and its five variants on Vitis HLS, a widely used FPGA HLS tool. Experimental results show that TEPACS outperforms the baselines by at least 11.17% in terms of the bug-finding capability. In one month, TEPACS detected 34 bugs on the latest version of Vitis HLS, of which 9 bugs have been confirmed.

Memory allocation is a fundamental operation for managing memory objects in many programming languages. Misusing allocated memory objects (e.g.,buffer overflowanduse-after-free) can have catastrophic consequences. Symbolic execution-based approaches have been used to detect such memory errors, benefiting from their capabilities in automatic path exploration and test case generation. However, existing symbolic execution engines still suffer from fundamental limitations in modeling dynamic memory layouts; they either represent the locations of memory objects as concrete addresses and thus limit their analyses only to specific address layouts and miss errors that may only occur when the objects are located at special addresses, or represent the locations as simple symbolic variables without sufficient constraints and thus suffer from memory state explosion when they execute read/write operations involving symbolic addresses. Such limitations hinder the existing symbolic execution engines from effectively detecting certain memory errors. In this study, we proposeSymLoc, a symbolic execution-based approach that uses concretely mapped symbolic memory locations to alleviate the limitations mentioned above. Specifically, a new integration of three techniques is designed inSymLoc: (1) the symbolization of addresses and encoding of symbolic addresses into path constraints, (2) the symbolic memory read/write operations using a symbolic-concrete memory map, and (3) the automatic tracking of the uses of symbolic memory locations. We buildSymLocon top of the well-known symbolic execution engine KLEE and demonstrate its benefits in terms of memory error detection and code coverage capabilities. Our evaluation results show that: for address-specific spatial memory errors,SymLoccan detect 23 more errors inGNU Coreutils,Make, andm4programs that are difficult for other approaches to detect, and cover 15% and 48% more unique lines of code in the programs than two baseline approaches; for temporal memory errors,SymLoccan detect 8%-64% more errors in the Juliet Test Suite than various existing state-of-the-art memory error detectors. We also present two case studies to show sample memory errors detected bySymLocalong with their root causes and implications.

Compiler bugs pose a significant threat to safety-critical applications, and promptly as well as effectively isolating these bugs is crucial for assuring the quality of compilers. However, the limited availability of debugging information on reported bugs complicates the compiler bug isolation task. Existing compiler bug isolation approaches typically convert the problem into a test program mutation problem, but they are still limited by ineffective mutation strategies or high human effort requirements. Drawing inspiration from the recent progress of pre-trained Large Language Models (LLMs), such as ChatGPT, in code generation, we propose a new approach named LLM4CBI to utilize LLMs to generate effective test programs for compiler bug isolation. However, using LLMs directly for test program mutation may not yield the desired results due to the challenges associated with formulating precise prompts and selecting specialized prompts. To overcome the challenges, three new components are designed in LLM4CBI. First, LLM4CBI utilizes a program complexity-guided prompt production component, which leverages data and control flow analysis to identify the most valuable variables and locations in programs for mutation. Second, LLM4CBI employs a memorized prompt selection component, which adopts reinforcement learning to select specialized prompts for mutating test programs continuously. Third, a test program validation component is proposed to select specialized feedback prompts to avoid repeating the same mistakes during the mutation process. Compared with the state-of-the-art approaches (DiWi and RecBi) over 120 real bugs from the two most popular compilers, namely GCC and LLVM, our evaluation demonstrates the advantages of LLM4CBI: It can isolate 69.70%/21.74% and 24.44%/8.92% more bugs than DiWi and RecBi within Top-1/Top-5 ranked results. Additionally, we demonstrate that the LLMs component (i.e., GPT-3.5) used in LLM4CBI can be easily replaced by other LLMs while still achieving reasonable results in comparison to related studies.

Code comments are a crucial source of software documentation that captures various aspects of the code. Such comments play a vital role in understanding the source code and facilitating communication between developers. However, with the iterative release of software, software projects become larger and more complex, leading to a corresponding increase in issues such as mismatched, incomplete, or outdated code comments. These inconsistencies in code comments can misguide developers and result in potential bugs, and there has been a steady rise in reports of such inconsistencies over time. Despite numerous methods being proposed for detecting code comment inconsistencies, their learning effect remains limited due to a lack of consideration for issues such as characterization noise and labeling errors in datasets. To overcome these limitations, we propose a novel approach called MCCL that first removes noise from the dataset and then detects inconsistent code comments in a timely manner, thereby enhancing the model's learning ability. Our proposed model facilitates better matching between code and comments, leading to improved development of software engineering projects. MCCL comprises two components, namely method comment detection and confidence learning denoising. The method comment detection component captures the intricate relationships between code and comments by learning their syntactic and semantic structures. It correlates the code and comments through an attention mechanism to identify how changes in the code affect the comments. Furthermore, confidence learning denoising component of MCCL identifies and removes characterization noises and labeling errors to enhance the quality of the datasets. This is achieved by implementing principles such as pruning noisy data, counting with probabilistic thresholds to estimate noise, and ranking examples to train with confidence. By effectively eliminating noise from the dataset, our model is able to more accurately learn inconsistencies between comments and source code. Our experiments on 1,518 open-source projects demonstrate that MCCL can accurately detect inconsistencies, achieving an averageF1-scoreof 82.6%. This result outperforms state-of-the-art methods by 2.4% to 28.0%. Therefore, MCCL is more effective in identifying inconsistent comments based on code changes compared to existing approaches.

Engineers frequently generate embedded code from Simulink models for control applications. However, target applications using the code could behave unexpectedly, due to the bugs in code generation. In this study, we propose MOPART, the first model partition based differential testing method for code generation testing in Simulink. MOPART uses multiple-way network partitioning to generate diverse bug-triggering Simulink models to thoroughly exercise the code generation process. MOPART then finds bugs by analyzing the outputs of these Simulink models with differential testing. Experiments show that MOPART significantly outperforms existing approaches, which finds 11 confirmed code generation bugs in only two weeks.

Deep learning techniques have shown promising performance in automated software maintenance tasks associated with bug reports. Currently, all existing studies learn the customized representation of bug reports for a specific downstream task. Despite early success, training multiple models for multiple downstream tasks faces three issues: complexity, cost, and compatibility, due to the customization, disparity, and uniqueness of these automated approaches. To resolve the above challenges, we propose RepresentThemAll, a pre-trained approach that can learn the universal representation of bug reports and handle multiple downstream tasks. Specifically, RepresentThemAll is a universal bug report framework that is pre-trained with two carefully designed learning objectives: one is the dynamic masked language model and another one is a contrastive learning objective, “find yourself”. We evaluate the performance of RepresentThemAll on four downstream tasks, including duplicate bug report detection, bug report summarization, bug priority prediction, and bug severity prediction. Our experimental results show that RepresentThemAll outperforms all baseline approaches on all considered downstream tasks after well-designed fine-tuning.

Intel's SGX is a confidential computing technique. It allows key functionalities of C/C++/native applications to be confidentially executed in hardware enclaves. However, numerous cloud applications are written in Java. For supporting their confidential computing, state-of-the-art approaches deploy Java Virtual Machines (JVMs) in enclaves and perform confidential computing on JVMs. Meanwhile, these JVM-in-enclave solutions still suffer from serious limitations, such as heavy overheads of running JVMs in enclaves, large attack surfaces, and deep computation stacks. To mitigate the above limitations, we for-malize a Secure Closed-World (SCW) principle and then propose Lejacon, a lightweight and efficient approach to Java confidential computing. The key idea is, given a Java application, to (1) separately compile its confidential computing tasks into a bundle of Native Confidential Computing (NCC) services; (2) run the NCC services in enclaves on the Trusted Execution Environment (TEE) side, and meanwhile run the non-confidential code on a JVM on the Rich Execution Environment (REE) side. The two sides interact with each other, protecting confidential computing tasks and as well keeping the Trusted Computing Base (TCB) size small. We implement Lejacon and evaluate it against OcclumJ (a state-of-the-art JVM-in-enclave solution) on a set of benchmarks using the BouncyCastle cryptography library. The evaluation results clearly show the strengths of Lejacon: it achieves compet-itive performance in running Java confidential code in enclaves; compared with OcclumJ, Lejacon achieves speedups by up to 16.2x in running confidential code and also reduces the TCB sizes by 90+% on average.

JavaScript (JS) transpilers translate JS programs from a higher grammar standard to a lower one, which are widely used to ensure the compatibility of JS features in software (e.g., browsers). However, JS transpilers can have bugs that lead to unintended behavior in the translated JS programs. Existing JS program generation approaches could not test JS transpilers effectively since it is hard to generate a large number of valid JS programs in specific grammar standards. In this paper, we propose TransFuzz, a grammar-guided mutation approach to find JS transpiler bugs.The key insight of TransFuzz is to generate syntax-specific JS programs by mutating the abstract syntax trees (ASTs) of JS programs with the guidance of the specific grammar. First, Trans- Fuzz parses JS programs collected from open-source platforms into ASTs to obtain subtrees and leaf nodes containing specific JS syntax. Then, a grammar-guided approach is developed in TransFuzz to mutate the ASTs of the given JS programs guided by different versions of JS grammar standards. In addition, mutation operations could introduce grammatical errors. To improve the correctness of the mutated ASTs, TransFuzz develops heuristic-based correction rules to correct reference errors, type errors, and syntax errors in the mutated ASTs. After correction, the mutated ASTs are converted to the corresponding JS programs. Finally, based on differential testing, TransFuzz utilizes the generated JS programs to detect JS transpiler bugs.Our evaluation shows that TransFuzz significantly outperforms existing JS program generation approaches by triggering 47.82%-385.71% more JS transpiler bugs. Within ten months, we have reported 73 bugs on two popular JS transpilers babel and swc, of which 58 have been confirmed.

WebAssembly runtime is the infrastructure for executing WebAssembly, which is widely used as an execution engine by web browsers or blockchain platforms. Bugs in the WebAssembly runtime can lead to unexpected behavior and even security vulnerabilities in any application that relies on it. Therefore, to aid developers in understanding the WebAssembly runtime, a thorough investigation of bugs in the WebAssembly runtime should be conducted. To accomplish this, we carry out the first empirical analysis of 867 real bugs across four popular WebAssembly runtimes (V8, SpiderMonkey, Wasmer, and Wasmtime). We analyze the WebAssembly runtime bug characteristics based on their root causes, symptoms, bug-fixing time, and the number of files and lines of code involved in the bug fixes. Here are a few major research findings: 1) Incorrect Algorithm Implementation accounts for 25.49% of WebAssembly runtime bugs, the most prevalent of all root causes; 2) The most prevalent symptom is Crash, which accounts for 56.86% of WebAssembly runtime bugs; 3) At the median, the bug-fixing time are 13, 4, 5, and 6 days for V8, SpiderMonkey, Wasmer, and Wasmtime respectively; 4) Over 50% of bug fixes in the four WebAssembly runtimes involve only one file, while more than 90% of bug fixes involve no more than 8 files; 5) The median source code lines for bug fixes for V8, SpiderMonkey, Wasmer, and Wasmtime are 18.5, 14, 26, and 36 lines, respectively. Overall, our research summarizes 18 findings and discusses the broad implications for WebAssembly runtime bug detection, localization, debugging, and repair based on the key findings.

C++ is a widely used programming language and the C++ front-end is a critical part of a C++ compiler. Although many techniques have been proposed to test compilers, few studies are devoted to detecting bugs in C++ compiler. In this study, we take the first step to detect bugs in C++ compiler front-ends. To do so, two main challenges need to be addressed, namely, the acquisition of test programs that are more likely to trigger bugs in compiler front-ends and the bug identification from complicated compiler outputs. In this article, we propose a novel framework namedCcoftto detect bugs in C++ compiler front-ends. To address the first challenge,Ccoftimplements a practical program generator. The generator first transforms C++ grammars into a flexible structured format and then utilizes an equal-chance selection (ECS) strategy to conduct structure-aware grammar mutation to generate diverse C++ programs. Next,Ccoftemploys a set of differential testing strategies to identify various kinds of bugs in C++ compiler front-ends by comparing complex outputs emitted by C++ compilers, thus tackling the second challenge. Empirical evaluation results over two mainstream compilers (i.e., GCC and Clang) show thatCcoftgreatly improves two state-of-the-art approaches (i.e., Dharma and Grammarinator) by 135% and 111% in terms of the numbers of detected bugs, respectively. By runningCcoftfor three months, we have successfully reported 136 bugs for two C++ compilers, of which 78 (57 confirmed, assigned, or fixed) for GCC and 58 (10 confirmed or fixed) for Clang.

Application review event inference aims to assess the effectiveness of application problems in response to user actions, which enables application developers to promptly discover and address potential issues in various applications, thereby improving their development and maintenance efficiency. Despite the development of event inference models for app reviews, which extract them as user action and app problem events and establish a relationship model between events and inference labels, the accuracy of these models is constrained due to limitations in labeling and characterizing noise and the lack of robustness and generalization. To address this challenge, we propose a model called Easy Data Augmentation for Application Reviews Event Inference (short for EDA-AREI), which comprises a denoising component, data augmentation component, and event inference prediction component. Specifically, the denoising component identifies labels and characterizes noisy data to enhance dataset quality, the data augmentation component replaces non-stop words with synonyms to increase textual diversity, and the event inference and prediction component reconstructs the classifier using denoised and augmented data. Experimental results on six datasets of one-star app reviews in the Apple App Store demonstrate that the EDA-AREI method achieves anAccuracyof 71.19%, 79.14%, 69.05%, 69.02%, 68.24% and 68.48%, respectively, representing an improvement of 0.83%–2.09% compared to state-of-the-art models. Regarding theF1-score, EDA-AREI achieves values of 71.30%, 69.93%, and 68.76% on the threshold_0.5, k-means_2, and random datasets, respectively, outperforming state-of-the-art models by 1.89%–4.02%. Furthermore, EDA-AREI achievesAUCvalues of 75.66% and 73.37% on the threshold_0.5 and k-means_2 datasets, respectively. As a result, EDA-AREI demonstrates substantial improvements inAccuracy, as well as enhancedF1-scoreandAUCacross most datasets, thereby enhancing the model's accuracy and robustness in identifying related action-problem pairs.

The emergence of numerous fork-based development platforms facilitates the development of Open-Source Software (OSS) projects. Developers across the world can fork software projects and submit their Pull Requests (PRs) to the projects. However, as the number of forks increases, numerous duplicate PRs might be submitted. These duplicate PRs may cause extra code review workload and frustrate developers working on the projects. To detect duplicate PRs, many approaches have been proposed, which analyze the similarity of different elements in PRs. However, previous approaches still suffer from unsatisfied detection accuracy due to two challenges. That is, they ignore the syntactic structural information of text elements in PRs and lack the joint reasoning between different elements of two PRs. In this study, we propose an automated duplicate PRs detector namedDupHunter(Duplicate PRsHunter), which includes a graph embedding component and a duplicate PRs detection component to address the above challenges. The graph embedding component uses a feature graph to represent a PR. It encodes the syntactic structure and semantics of text elements (e.g., the title and the description), as well as the knowledge of non-text elements (e.g., the submission time), to address the syntactic structural information challenge. The duplicate PRs detection component tackles the joint reasoning challenge using a graph matching network, which enables the information exchange and matching across different elements of two feature graphs with an attention coefficient mechanism. Experiments on 26 open-source projects show that DupHunter achieves an averageF1-score@1value of 0.650, significantly outperforming the state-of-the-art approaches by 3.2% to 48.1%. DupHunter can accurately detect duplicate PRs, with an averagePrecision@1value of 0.922 and an averageRecall@1value of 0.502.

As one of the most important resources to express the semantics of source code, identifiers are usually composed of several common or domain-specific terms and abbreviations, thus heavily hindering developers from analyzing and comprehending source code. Hence, it is very necessary to normalize identifiers, which aims to align the vocabulary found in identifiers with natural language words found in other software artifacts. Even though researchers have proposed several identifier normalization approaches in the literature, these approaches only rely on the lexical information in identifiers and related source code entities to normalize identifiers, suffering from the lack of deep semantic understanding of identifiers. In this paper, we propose an effective and efficient identifier normalization approach BEQAIN to split identifiers into their composing words and expand the enclosed abbreviations. Specifically, BEQAIN employs a deep learning model, which is mainly composed of a Bidirectional Encoder Representation from Transformers (BERT) layer and a Conditional Random Fields (CRF) layer to embed identifiers into low-level vectors and learn the identifier splitting patterns. The BERT-CRF network is also combined with a pre-processing component and a post-processing component to resolve the problems of over-splitting and under-splitting so as to improve the identifier splitting performance. Furthermore, BEQAIN also employs a Question Answering (Q&A) system to learn the abbreviation expansion mappings and leverages the current programming context to determine the exactly correct expansion when there are multiple expansions for specific abbreviations. After BEQAIN is fully trained, it can be used to normalize identifiers. We conduct extensive experiments to validate the effectiveness and efficiency of BEQAIN over two publicly available datasets with nine projects. Experimental results show that BEQAIN achieves the overall average Accuracy of 80.20% and outperforms the existing state-of-the-art approach by 9.88% in normalizing identifiers. The pre-processing and post-processing components could improve the Accuracy of BEQAIN in identifier splitting by 11.70%. Employing the programming context information could improve the Accuracy of BEQAIN in abbreviation expansion by 11.15% on average. In addition, the average normalization time of BEQAIN is less than one second. Finally, we also discuss some observations for the road ahead for identifier normalization to inspire other researchers.

Neural Architecture Search (NAS) is widely used in industry, searching for neural networks meeting task requirements. Meanwhile, it faces a challenge in scheduling networks satisfying memory constraints. This paper proposes HMCOS that performs hierarchical memory-constrained operator scheduling of NAS networks: given a network, HMCOS constructs a hierarchical computation graph and employs an iterative scheduling algorithm to progressively reduce peak memory footprints. We evaluate HMCOS against RPO and Serenity (two popular scheduling techniques). The results show that HMCOS outperforms existing techniques in supporting more NAS networks, reducing 8.7~42.4% of peak memory footprints, and achieving 137--283x of speedups in scheduling.

Software reproducibility plays an essential role in establishing trust between source code and the built artifacts, by comparing compilation outputs acquired from independent users. Although the testing for unreproducible builds could be automated, fixing unreproducible build issues poses a set of challenges within the reproducible builds practice, among which we consider the localization granularity and the historical knowledge utilization as the most significant ones. To tackle these challenges, we propose a novel approach RepFix that combines tracing-based fine-grained localization with history-based patch generation mechanisms.

Program generators play a critical role in generating bug-revealing test programs for compiler testing. However, existing program generators have been tamed nowadays (i.e., compilers have been hardened against test programs generated by them), thus calling for new solutions to improve their capability in generating bug-revealing test programs. In this study, we propose a framework named Remgen, aiming to Remanufacture a random program Generator for this purpose. RemgEnaddresses the challenges of the synthesis of diverse code snippets at a low cost and the selection of the bug-revealing code snippets for constructing new test programs. More specifically, RemgEnfirst designs a grammar-aided synthesis mechanism to synthesize diverse code snippets. Then, a grammar coverage-guided strategy is used to select the most diverse code snippets that may be bug-revealing. As a case study to demonstrate the effectiveness of the Remgen framework, we have remanufactured an old C program generator CCG and named it REMCCG. Our evaluation results show that REMCCG can generate significantly more bug-revealing test programs than the original CCG; notably, Remccg has found 56 new bugs for two mature compilers (i.e., GCC and LLVM), of which 37 have already been fixed by their developers.

As a popular Cyber-Physical System (CPS) development tool chain, MathWorks Simulink is widely used to prototype CPS models in safety-critical applications, e.g., aerospace and healthcare. It is crucial to ensure the correctness and reliability of Simulink compiler (i.e., the compiler module of Simulink) in practice since all CPS models depend on compilation. However, Simulink compiler testing is challenging due to millions of lines of source code and the lack of the complete formal language specification. Although several methods have been proposed to automatically test Simulink compiler, there still remains two challenges to be tackled, namely the limited variant space and the insufficient mutation diversity. To address these challenges, we propose COMBAT, a new differential testing method for Simulink compiler testing. COMBAT includes an EMI (Equivalence Modulo Input) mutation component and a diverse variant generation component. The EMI mutation component inserts assertion statements (e.g., If /While blocks) at arbitrary points of the seed CPS model. These statements break each insertion point into true and false branches. Then, COMBAT feeds all the data passed through the insertion point into the true branch to preserve the equivalence of CPS variants. In such a way, the body of the false branch could be viewed as a new variant space, thus addressing the first challenge. The diverse variant generation component uses Markov chain Monte Carlo optimization to sample the seed CPS model and generate complex mutations of long sequences of blocks in the variant space, thus addressing the second challenge. Experiments demonstrate that COMBAT significantly outperforms the state-of-the-art approaches in Simulink compiler testing. Within five months, COMBAT has reported 16 valid bugs for Simulink R2021b, of which 11 bugs have been confirmed as new bugs by MathWorks Support.

Symbolic execution (SE) has been widely adopted for automatic program analysis and software testing. Many SE engines (e.g., KLEE or Angr) need to interpret certain Intermediate Representations (IR) of code during execution, which may be slow and costly. Although a plurality of studies proposed to accelerate SE, few of them consider optimizing the internal interpretation operations. In this paper, we propose FastKLEE, a faster SE engine that aims to speed up execution via reducing redundant bound checking of type-safe pointers during IR code interpretation. Specifically, in FastKLEE, a type inference system is first leveraged to classify pointer types (i.e., safe or unsafe) for the most frequently interpreted read/write instructions. Then, a customized memory operation is designed to perform bound checking for only the unsafe pointers and omit redundant checking on safe pointers. We implement FastKLEE on top of the well-known SE engine KLEE and combined it with the notable type inference system CCured. Evaluation results demonstrate that FastKLEE is able to reduce by up to 9.1% (5.6% on average) as the state-of-the-art approach KLEE in terms of the time to explore the same number (i.e., 10k) of execution paths. FastKLEE is opensourced at https://github.com/haoxintu/FastKLEE. A video demo of FastKLEE is available at https://youtu.be/fjV_a3kt-mo.

Pattern matching can be used to calculate the support of patterns, and is a key issue in sequential pattern mining (or sequence pattern mining). Nonoverlapping pattern matching means that two occurrences cannot use the same character in the sequence at the same position. Approximate pattern matching allows for some data noise, and is more general than exact pattern matching. At present, nonoverlapping approximate pattern matching is based on Hamming distance, which cannot be used to measure the local approximation between the subsequence and pattern, resulting in large deviations in matching results. To tackle this issue, we present a Nonoverlapping Delta and gamma approximate Pattern matching (NDP) scheme that employs the (δ,γ)-distance to give an approximate pattern matching, where the local and the global distances do not exceed δ and γ, respectively. We first transform the NDP problem into a local approximate Nettree and then construct an efficient algorithm, called the local approximate Nettree for NDP (NetNDP). We propose a new approach called the Minimal Root Distance which allows us to determine whether or not a node has root paths that satisfy the global constraint and to prune invalid nodes and parent-child relationships. NetNDP finds the rightmost absolute leaf of the max root, searches for the rightmost occurrence from the rightmost absolute leaf, and deletes this occurrence. We iterate the above steps until there are no new occurrences. Numerous experiments are used to verify the performance of the proposed algorithm.

Compiler testing is the most widely used way to assure compiler quality. However, since compilers require a large number of sophisticated test programs as inputs, the existing approaches in compiler testing still have a limited capability in generating both syntactically valid and diverse test programs. In this paper, we propose DeepGen, a deep learning-based approach to support compiler testing through the inference of a generative model for compiler inputs. First, DeepGen trains a Transformer-XL model based on a large corpus of seed programs, and uses the trained model to generate syntactically valid programs. Then, DeepGen adopts a sampling strategy in the inference phase to generate diverse test programs. Finally, DeepGen leverages differential testing on the generated programs to discover compiler bugs. We have evaluated DeepGen over two popular C++ compilers GCC and LLVM, and the results confirm the effectiveness of our approach. DeepGen detects 35.29%, 53.33%, and 187.50% more bugs than three existing approaches, i.e. DeepSmith, DeepFuzz, and Csmith, respectively. In addition, 30.43% bugs detected by DeepGen are not detected by other approaches. Furthermore, DeepGen has successfully detected 38 bugs in the latest development versions of GCC and LLVM; 21 of them have been confirmed/fixed by the developers.

As a novel deep learning model, gcForest has been widely used in various applications. However, current multi-grained scanning of gcForest produces many redundant feature vectors, and this increases the time cost of the model. To screen out redundant feature vectors, we introduce a hashing screening mechanism for multi-grained scanning and propose a model called HW-Forest which adopts two strategies: hashing screening and window screening. HW-Forest employs perceptual hashing algorithm to calculate the similarity between feature vectors in hashing screening strategy, which is used to remove the redundant feature vectors produced by multi-grained scanning and can significantly decrease the time cost and memory consumption. Furthermore, we adopt a self-adaptive instance screening strategy called window screening to improve the performance of our approach, which can achieve higher accuracy without hyperparameter tuning on different datasets. Our experimental results show that HW-Forest has higher accuracy than other models, and the time cost is also reduced.

Compiling source code effectively to meet various criteria is a critical task in software engineering. Especially, code size reduction has attracted much attention from both industry and academia due to the requirement of resource utilization. Generally, developers rely on compiler optimization passes to realize code size reduction. However, it is impractical to select a desirable optimization sequence manually since a wide variety of optimization passes are integrated into a compiler. Evolutionary algorithms offer an impressive way to alleviate this problem. Nevertheless, previous approaches fail to balance the exploitation and exploration of the search space. Moreover, the expensive fitness evaluation requires actual compilation, which makes the evolution rather time-consuming. To tackle the challenges, we propose a novel approach SMARTEST, which characterizes the systematic exploitation of a huge volume of historical compilation information. Specifically, SMARTEST comprises two components: 1) a local search operator to enhance the solution quality; and 2) a data-driven surrogate model to avoid expensive fitness evaluation. We evaluate the effectiveness of SMARTEST over the cBench benchmark suite. Experimental results indicate that SMARTEST outperforms the standard level -Os by 2.17% on average, and achieves 1.2 times code size reduction compared with the genetic algorithm. Furthermore, experimental results over the benchmark suite evidently show that SMARTEST gets a better result and takes less actual fitness evaluations than its variants, which demonstrates the contribution of the local search and the surrogate model.

Compiler bugs may be triggered when programs are optimized with optimization sequences. However, diagnosing compiler optimization sequence bugs is difficult due to limited debugging information. Although some techniques (e.g., DiWi and RecBi) have been proposed to automatically localize compiler bugs, no systematic work has been conducted to automatically localize compiler optimization sequence bugs. In this article, we propose LocSeq, a novel technique to automatically localize compiler optimization sequence bugs of LLVM. The core insight of LocSeq is based on the fact that the behaviors of optimizations may be influenced by each other, and thus, the innocent files may be excluded by constructing bug-free optimization sequences. First, given a buggy optimization sequence that triggers a compiler bug, in LocSeq, we transform the problem of the localization for a compiler optimization sequence bug to the problem of the construction for bug-free optimization sequences, which are helpful to localize buggy compiler files. Then, a constrained genetic algorithm is presented in LocSeq to generate a set of bug-free optimization sequences that share similar compiler execution traces with the buggy optimization sequence. Finally, LocSeq leverages a spectrum-based bug localization technique to localize the compiler optimization sequence bug by comparing the execution traces between bug-free optimization sequences and the buggy optimization sequence. To evaluate the effectiveness of LocSeq, we build a benchmark, including 60 optimization sequence bugs of LLVM, and compare LocSeq with the state-of-the-art techniques DiWi and RecBi. The experimental results show that LocSeq significantly outperforms DiWi and RecBi by up to 366.66%/72.27% and 250.00%/56.00% for localizing optimization sequence bugs within Top-1/5 files, respectively.

Code completion is to predict the rest of a statement a developer is typing. Although advanced code completion approaches have greatly improved the accuracy of code completion in modern IDEs, it remains challenging to predict project-specific API method invocations or field accesses because little knowledge about such elements could be learned in advance. To this end, in this paper we propose an accurate approach called HeeNAMA to suggesting the next project-specific API member access. HeeNAMA focuses on a specific but common case of code completion: suggesting the following member access whenever a project-specific API instance is followed by a dot on the right hand side of an assignment. By focusing on such a specific case, HeeNAMA can take full advantages of the context of the code completion, including the type of the left hand side expression of the assignment, the identifier on the left hand side, the type of the base instance, and similar assignments typed in before. All such information together enables highly accurate code completion. Given an incomplete assignment, HeeNAMA generates the initial candidate set according to the type of the base instance, and excludes those candidates that are not type compatible with the left hand side of the assignment. If the enclosing project contains assignments highly similar to the incomplete assignment, it makes suggestions based on such assignments. Otherwise, it selects the one from the initial candidate set that has the greatest lexical similarity with the left hand side of the assignment. Finally, it employs a neural network to filter out risky predictions, which guarantees high precision. Evaluation results on open-source applications suggest that compared to the state-of-the-art approaches and the state-of-the-practice tools HeeNAMA improves precision and recall by 70.68 and 25.23 percent, relatively.

Optimization sequences are often employed in compilers to improve the performance of programs, but may trigger critical compiler bugs, e.g., compiler crashes. Although many methods have been developed to automatically test compilers, no systematic work has been conducted to detect compiler bugs when applying arbitrary optimization sequences. To resolve this problem, two main challenges need to be addressed, namely the acquisition of representative optimization sequences and the selection of representative testing programs, due to the enormous number of optimization sequences and testing programs. In this study, we propose CTOS, a novel compiler testing method based on differential testing, for detecting compiler bugs caused by optimization sequences of LLVM. CTOS first leverages the technique Doc2Vec to transform optimization sequences into vectors to capture the information of optimizations and their orders simultaneously. Second, a method based on the region graph and call relationships is developed in CTOS to construct the vector representations of the testing program, such that the semantics and the structure information of programs can be captured simultaneously. Then, with the vector representations of optimization sequences and testing programs, a “centroid” based selection scheme is proposed to address the above two challenges. Finally, CTOS takes in the representative optimization sequences and testing programs as inputs, and tests each testing program with all the representative optimization sequences. If there is an output that is different from the majority of others of a given testing program, then the corresponding optimization sequence is deemed to trigger a compiler bug. Our evaluation demonstrates that CTOS significantly outperforms the baselines by up to$24.76\% \sim 50.57\%$in terms of the bug-finding capability on average. Within seven month evaluations on LLVM, we have reported 104 valid bugs within 5 types, of which 21 have been confirmed or fixed. Most of those bugs are crash bugs (57) and wrong code bugs (24). 47 unique optimizations are identified to be faulty and 15 of them are loop related optimizations.

With the plain text descriptions of design patterns, developers could better learn and understand the definitions and usage scenarios of design patterns. To facilitate the automatic usage of these descriptions, e.g., recommending design patterns by free-text queries, design patterns and natural languages should be adequately associated. Existing studies usually use texts in design pattern books as the representations of design patterns to calculate similarities with the queries. However, this way is problematic. Lots of information of design patterns may be absent from design pattern books and many words would be out of vocabulary due to the content limitation of these books. To overcome these issues, a more comprehensive method should be constructed to estimate the relatedness between design patterns and natural language words. Motivated by Word2Vec, in this study, we propose DPWord2Vec that embeds design patterns and natural language words into vectors simultaneously. We first build a corpus containing more than 400 thousand documents extracted from design pattern books, Wikipedia, and Stack Overflow. Next, we redefine the concept of context window to associate design patterns with words. Then, the design pattern and word vector representations are learnt by leveraging an advanced word embedding method. The learnt design pattern and word vectors can be universally used in textual description based design pattern tasks. An evaluation shows that DPWord2Vec outperforms the baseline algorithms by 24.2-120.9 percent in measuring the similarities between design patterns and words in terms of Spearman’s rank correlation coefficient. Moreover, we adopt DPWord2Vec on two typical design pattern tasks. In the design pattern tag recommendation task, the DPWord2Vec-based method outperforms two state-of-the-art algorithms by 6.6 and 32.7 percent respectively when considering$Recall@10$. In the design pattern selection task, DPWord2Vec improves the existing methods by 6.5-70.7 percent in terms of MRR.

Compiler diagnostic warnings help developers identify potential programming mistakes during program compilation. However, these warnings could be erroneous due to the defects of compiler warning diagnostics. Although the existing technique (i.e., Epiphron) can automatically generate test programs for compiler warning defect detection, the effectiveness of Epiphron on defect-finding is still limited, due to the limitation for generating warning-sensitive test program structures. Therefore, in this paper, we propose a DIversity-guided PROgram Mutation approach, called DIPROM, to construct diverse warning-sensitive programs for effective compiler warning defect detection. Given a seed test program, DIPROM first removes its dead code to reduce false positive warning defects. Then, the abstract syntax tree (AST) of the test program is constructed; DIPROM iteratively mutates the structures of the AST to generate warning-sensitive program variants. To effectively construct diverse warning-sensitive structures, DIPROM applies a novel diversity-guided strategy to generate program variants in each iteration. With the generated program variants, differential testing is conducted to detect warning defects in different compilers. In the experiments, we evaluate DIPROM with two popular C compilers (i.e., GCC and Clang). Experimental results show that DIPROM significantly outperforms three state-of-the-art approaches (i.e., HiCOND, Epiphron, and Hermes) by up to 18.93%$\sim$76.74% in terms of the bug-finding capability on average. Meanwhile, DIPROM is efficient, which spends less time on finding the same average number of warning defects. We at last applied DIPROM to the latest development versions of GCC and Clang. After two months’ running, we reported 8 new warning defects; 5 of them have been confirmed/fixed by developers.

Software developers frequently invoke deep learning (DL) APIs to incorporate learning solutions into software systems. However, misuses of these APIs can cause various DL faults, such as tensor shape faults. Tensor shape faults occur when restriction conditions of operations are not met; they are prevalent in practice, leading to many system crashes. Meanwhile, researchers and engineers still face a strong challenge in detecting tensor shape faults ─ static techniques incur heavy overheads in defining detection rules, and the only dynamic technique requires human engineers to rewrite APIs for tracking shape changes. To address the above challenge, we conduct a deep empirical study on crashing tensor shape faults (i.e., those causing programs to crash), categorizing them into four types and revealing twelve repair patterns. We then propose and implement Tensfa, an approach to detecting and repairing crashing tensor shape faults. Tensfa takes a machine learning method to learn from crash messages and employs decision trees in detecting tensor shape faults. Tensfa also provides the first automated solution to repairing the detected faults: it tracks shape properties by a customized Python debugger, analyzes their data dependences, and uses the twelve patterns to generate patches. We construct SFData, a set of 146 buggy programs with crashing tensor shape faults. Our Tensfa has been implemented and evaluated on SFData and IslamData (another dataset of tensor shape faults). The results clearly show the effectiveness of Tensfa. In particular, Tensfa achieves the state-of-the-art results: it reaches an F1-score of 96.88% in detecting the faults and repairs 80 out of 146 buggy programs in SFData.

Million of mobile apps have been released to the market. Developers need to maintain these apps so that they can continue to benefit end users. Developers usually extract useful information from user reviews to maintain and evolve mobile apps. One of the important activities that developers need to do while reading user reviews is to locate the source code related to requested changes. Unfortunately, this manual work is costly and time consuming since: (1) an app can receive thousands of reviews, and (2) a mobile app can consist of hundreds of source code files. To address this challenge, Palombaet al.recently proposedCHANGEADVISORthat utilizes user reviews to locate source code to be changed. However, we find that it cannot identify real source code to be changed for part of reviews. In this work, we aim to advance Palombaet al.'s work by proposing a novel approach that can achieve higher accuracy in change localization. Our approach first extracts the informative sentences (i.e., user feedback) from user reviews and identifies user feedback related to various problems and feature requests, and then cluster the corresponding user feedback into groups. Each group reports the similar users’ needs. Next, these groups are mapped to issue reports by using$Word2Vec$. The resultant enriched text consisting of user feedback and their corresponding issue reports is used to identify source code classes that should be changed by using our novelweight selection-based cosine similarity metric. We have evaluated the new proposed change request localization approach (Where2Change) on 31,597 user reviews and 3,272 issue reports of 10 open source mobile apps. The experiments demonstrate thatWhere2Changecan successfully locate more source code classes related to the change requests for more user feedback clusters thanCHANGEADVISORas demonstrated by higher Top-N and Recall values. The differences reach up to 17 for Top-1, 18.1 for Top-3, 17.9 for Top-5, and 50.08 percent for Recall. In addition, we also compare the performance ofWhere2Changeand two previous Information Retrieval (IR)-based fault localization technologies:BLUiRandBLIA. The results showed that our approach performs better than them. As an important part of our work, we conduct an empirical study to investigate the value of using both user reviews and historical issue reports for change request localization; the results shown that historical issue reports can help to improve the performance of change localization.

As one key resource to learn Application Programming Interfaces (APIs), a lot of API reference documentation lacks code samples with usage scenarios, thus heavily hindering developers from programming with APIs. Although researchers have investigated how to enrich API documentation with code samples from general code search engines, two main challenges remain to be resolved, including the quality challenge of acquiring high-quality code samples and the mapping challenge of matching code samples to usage scenarios. In this study, we propose a novel approach named ADECK towards enriching API documentation with code samples and corresponding usage scenarios by leveraging crowd knowledge from Stack Overflow, a popular technical Question and Answer (Q&A) website attracting millions of developers. Given an API related Q&A pair, a code sample in the answer is extensively evaluated by developers and targeted towards resolving the question under the specified usage scenario. Hence, ADECK can obtain high-quality code samples and map them to corresponding usage scenarios to address the above challenges. Extensive experiments on the Java SE and Android API documentation show that the number of code-sample-illustrated API types in the ADECK-enriched API documentation is 3.35 and 5.76 times as many as that in the raw API documentation. Meanwhile, the quality of code samples obtained by ADECK is better than that of code samples by the baseline approach eXoaDocs in terms of correctness, conciseness, and usability, e.g., the average correctness values of representative code samples obtained by ADECK and eXoaDocs are 4.26 and 3.28 on a 5-point scale in the enriched Java SE API documentation. In addition, an empirical study investigating the impacts of different types of API documentation on the productivity of developers shows that, compared against the raw and the eXoaDocs-enriched API documentation, the ADECK-enriched API documentation can help developers complete 23.81 and 14.29 percent more programming tasks and reduce the average completion time by 9.43 and 11.03 percent.

Developers increasingly rely on text matching tools to analyze the relation between natural language words and APIs. However, semantic gaps, namely textual mismatches between words and APIs, negatively affect these tools. Previous studies have transformed words or APIs into low-dimensional vectors for matching; however, inaccurate results were obtained due to the failure of modeling words and APIs simultaneously. To resolve this problem, two main challenges are to be addressed: the acquisition of massive words and APIs for mining and the alignment of words and APIs for modeling. Therefore, this study proposes Word2API to effectively estimate relatedness of words and APIs. Word2API collects millions of commonly used words and APIs from code repositories to address the acquisition challenge. Then, a shuffling strategy is used to transform related words and APIs into tuples to address the alignment challenge. Using these tuples, Word2API models words and APIs simultaneously. Word2API outperforms baselines by 10-49.6 percent of relatedness estimation in terms of precision and NDCG. Word2API is also effective on solving typical software tasks, e.g., query expansion and API documents linking. A simple system with Word2API-expanded queries recommends up to 21.4 percent more related APIs for developers. Meanwhile, Word2API improves comparison algorithms by 7.9-17.4 percent in linking questions in Question&Answer communities to API documents.

Code smells regularly cause potential software quality problems in software development. Thus, code smell detection has attracted the attention of many researchers. A number of approaches have been suggested in order to improve the accuracy of code smell detection. Most of these approaches rely solely on structural information (code metrics) extracted from source code and heuristic rules designed by people. In this paper, We propose a method-representation based model to represent the methods in textual code, which can effectively reflect the semantic relationships embedded in textual code. We also propose a deep learning based approach that combines method-representation and a CNN model to detect feature envy. The proposed approach can automatically extract semantic and features from textual code and code metrics, and can also automatically build complex mapping between these features and predictions. Evaluation results on open-source projects demonstrate that our proposed approach achieves better performance than the state-of-the-art in detecting feature envy.

High quality method names are critical for the readability and maintainability of programs. However, constructing concise and consistent method names is often challenging, especially for inexperienced developers. To this end, advanced machine learning techniques have been recently leveraged to recommend method names automatically for given method bodies/implementation. Recent large-scale evaluations also suggest that such approaches are accurate. However, little is known about where and why such approaches work or don't work. To figure out the state of the art as well as the rationale for the success/failure, in this paper we conduct an empirical study on the state-of-the-art approach code2vec. We assess code2vec on a new dataset with more realistic settings. Our evaluation results suggest that although switching to new dataset does not significantly influence the performance, more realistic settings do significantly reduce the performance of code2vec. Further analysis on the successfully recommended method names also reveals the following findings: 1) around half (48.3%) of the accepted recommendations are made on getter/setter methods; 2) a large portion (19.2%) of the successfully recommended method names could be copied from the given bodies. To further validate its usefulness, we ask developers to manually score the difficulty in naming methods they developed. Code2vec is then applied to such manually scored methods to evaluate how often it works in need. Our evaluation results suggest that code2vec rarely works when it is really needed. Finally, to intuitively reveal the state of the art and to investigate the possibility of designing simple and straightforward alternative approaches, we propose a heuristics based approach to recommending method names. Evaluation results on large-scale dataset suggest that this simple heuristics-based approach significantly outperforms the state-of-the-art machine learning based approach, improving precision and recall by 65.25% and 22.45%, respectively. The comparison suggests that machine learning based recommendation of method names may still have a long way to go.

Localization of the root causes for unreproducible builds during software maintenance is an important yet challenging task, primarily due to limited runtime traces from build processes and high diversity of build environments. To address these challenges, in this paper, we propose RepTrace, a framework that leverages the uniform interfaces of system call tracing for monitoring executed build commands in diverse build environments and identifies the root causes for unreproducible builds by analyzing the system call traces of the executed build commands. Specifically, from the collected system call traces, RepTrace performs causality analysis to build a dependency graph starting from an inconsistent build artifact (across two builds) via two types of dependencies: read/write dependencies among processes and parent/child process dependencies, and searches the graph to find the processes that result in the inconsistencies. To address the challenges of massive noisy dependencies and uncertain parent/child dependencies, RepTrace includes two novel techniques: (1) using differential analysis on multiple builds to reduce the search space of read/write dependencies, and (2) computing similarity of the runtime values to filter out noisy parent/child process dependencies. The evaluation results of RepTrace over a set of real-world software packages show that RepTrace effectively finds not only the root cause commands responsible for the unreproducible builds, but also the files to patch for addressing the unreproducible issues. Among its Top-10 identified commands and files, RepTrace achieves high accuracy rate of 90.00% and 90.56% in identifying the root causes, respectively.

The rapidly evolving mobile applications (apps) have brought great demand for developers to identify new features by inspecting the descriptions of similar apps and acquire missing features for their apps. Unfortunately, due to the huge number of apps, this manual process is time-consuming and unscalable. To help developers identify new features, we propose a new approach named SAFER. In this study, we first develop a tool to automatically extract features from app descriptions. Then, given an app, we leverage the topic model to identify its similar apps based on the extracted features and API names of apps. Finally, we design a feature recommendation algorithm to aggregate and recommend the features of identified similar apps to the specified app. Evaluated over a collection of 533 annotated features from 100 apps, SAFER achieves a Hit@15 score of up to 78.68% and outperforms the baseline approach KNN+ by 17.23% on average. In addition, we also compare SAFER against a typical technique of recommending features from user reviews, i.e., CLAP. Experimental results reveal that SAFER is superior to CLAP by 23.54% in terms of Hit@15.

Recent years have witnessed the growing demands for resolving numerous bug reports in software maintenance. Aiming to reduce the time testers/developers take in perusing bug reports, the task of bug report summarization has attracted a lot of research efforts in the literature. However, no systematic analysis has been conducted on attribute construction, which heavily impacts the performance of supervised algorithms for bug report summarization. In this study, we first conduct a survey to reveal the existing methods for attribute construction in mining software repositories. Then, we propose a new method named Crowd-Attribute to infer new effective attributes from the crowd-generated data in crowdsourcing and develop a new tool named Crowdsourcing Software Engineering Platform to facilitate this method. With Crowd-Attribute, we successfully construct 11 new attributes and propose a new supervised algorithm named Logistic Regression with Crowdsourced Attributes (LRCA). To evaluate the effectiveness of LRCA, we build a series of large scale datasets with 105 177 bug reports. Experiments over both the public dataset SDS with 36 manually annotated bug reports and new large-scale datasets demonstrate that LRCA can consistently outperform the state-of-the-art algorithms for bug report summarization.

When implementing unfamiliar programming tasks, developers commonly search code examples and learn usage patterns of APIs from the code examples or reuse them by copy-pasting and modifying. For providing high-quality code examples, previous studies present several methods to recommend code snippets mainly based on information retrieval. In this paper, to provide better recommendation results, we propose ROSF, Recommending code Snippets with multi-aspect Features, a novel method combining both information retrieval and supervised learning. In our method, we recommend Top-K code snippets for a given free-form query based on two stages, i.e., coarse-grained searching and fine-grained re-ranking. First, we generate a code snippet candidate set by searching a code snippet corpus using an information retrieval method. Second, we predict probability values of the code snippets for different relevance scores in the candidate set by the learned prediction model from a training set, re-rank these candidate code snippets according to the probability values, and recommend the final results to developers. We conduct several experiments to evaluate our method in a large-scale corpus containing 921,713 real-world code snippets. The results show that ROSF is an effective method for code snippets recommendation and outperforms the-state-of-the-art methods by 20-41percent in Precision and 13-33 percent in NDCG.

Issue reports and Pull Requests (PRs) are two important kinds of artifacts of software projects in GitHub. It is common for developers to leave explicit links in issues/PRs that refer to the other issues/PRs during discussions. Existing studies have demonstrated the value of such links in identifying complex bugs and duplicate issue reports. However, there are no broad examinations of why developers leave links within issues/PRs and the potential impact of such links on software development. Without such knowledge, practitioners and researchers may miss various opportunities to develop practical techniques for better solving bug-fixing or feature implementation related tasks. To fill this gap, we conducted the first empirical study to explore the characteristics of a large number of links within 642,281 issues/PRs of 16,584 popular (>50 stars) Python projects in GitHub. Specifically, we first constructed an Issue Unit Network (IUN, we refer to issue reports or PRs as issue units) by making use of the links between issue units. Then, we manually checked a sample of 1,384 links in the IUN and concluded six major kinds of linking relationships between issue units. For each kind of linking relationships, we presented some common patterns that developers usually adopted while linking issue units. By further analyzing as many as 423,503 links that match these common patterns, we found several interesting findings which indicate potential research directions in the future, including detecting cross-project duplicate issue reports, using IUN to help better identify influential projects and core issue reports.

In this paper, we focus on investigating function based code clone detection and leveraging the structural information to measure the similarity of code fragments in the function level. The method first combines a variant of Abstract Syntax Tree(AST) to achieve more abstract code representations by using defined node types instead of the original node representations, and then adopts a local comparison algorithm, namely Smith Waterman, to calculate the similarity scores of pairs of code fragments in the function level. Experiments conducted over the five open-source datasets show that our method can achieve 92.46% in precision on average, and outperform the comparative algorithms by up to 10.94% and 4.02%, respectively. Meanwhile, experimental results show that our method can achieve 90.73% in precision on average in code clone detection over cross-projects.

Reproducibility is the ability of recreating identical binaries under pre-defined build environments. Due to the need of quality assurance and the benefit of better detecting attacks against build environments, the practice of reproducible builds has gained popularity in many open-source software repositories such as Debian and Bitcoin. However, identifying the unreproducible issues remains a labour intensive and time consuming challenge, because of the lacking of information to guide the search and the diversity of the causes that may lead to the unreproducible binaries.

Bug report summarization is an effective way to reduce the considerable time in wading through numerous bug reports. Although some supervised and unsupervised algorithms have been proposed for this task, their performance is still limited, due to the particular characteristics of bug reports, including the evaluation behaviours in bug reports, the diverse sentences in software language and natural language, and the domain-specific predefined fields. In this study, we conduct the first exploration of the deep learning network on bug report summarization. Our approach, called DeepSum, is a novel stepped auto-encoder network with evaluation enhancement and predefined fields enhancement modules, which successfully integrates the bug report characteristics into a deep neural network. DeepSum is unsupervised. It significantly reduces the efforts on labeling huge training sets. Extensive experiments show that DeepSum outperforms the comparative algorithms by up to 13.2% and 9.2% in terms of F-score and Rouge-n metrics respectively over the public datasets, and achieves the state-of-the-art performance. Our work shows promising prospects for deep learning to summarize millions of bug reports.

In crowdsourced mobile application testing, crowd workers help developers perform testing and submit test reports for unexpected behaviors. These submitted test reports usually provide critical information for developers to understand and reproduce the bugs. However, due to the poor performance of workers and the inconvenience of editing on mobile devices, the quality of test reports may vary sharply. At times developers have to spend a significant portion of their available resources to handle the low-quality test reports, thus heavily decreasing their efficiency. In this paper, to help developers predict whether a test report should be selected for inspection within limited resources, we propose a new framework named TERQAF to automatically model the quality of test reports. TERQAF defines a series of quantifiable indicators to measure the desirable properties of test reports and aggregates the numerical values of all indicators to determine the quality of test reports by using step transformation functions. Experiments conducted over five crowdsourced test report datasets of mobile applications show that TERQAF can correctly predict the quality of test reports with accuracy of up to 88.06% and outperform baselines by up to 23.06%. Meanwhile, the experimental results also demonstrate that the four categories of measurable indicators have positive impacts on TERQAF in evaluating the quality of test reports.

In software maintenance process, it is a fairly important activity to predict the severity of bug reports. However, manually identifying the severity of bug reports is a tedious and time-consuming task. So developing automatic judgment methods for predicting the severity of bug reports has become an urgent demand. In general, a bug report contains a lot of descriptive natural language texts, thus resulting in a high-dimensional feature set which poses serious challenges to traditionally automatic methods. Therefore, we attempt to use automatic feature selection methods to improve the performance of the severity prediction of bug reports. In this paper, we introduce a ranking-based strategy to improve existing feature selection algorithms and propose an ensemble feature selection algorithm by combining existing ones. In order to verify the performance of our method, we run experiments over the bug reports of Eclipse and Mozilla and conduct comparisons with eight commonly used feature selection methods. The experiment results show that the ranking-based strategy can effectively improve the performance of the severity prediction of bug reports by up to 54.76% on average in terms of [Formula: see text]-measure, and it also can significantly reduce the dimension of the feature set. Meanwhile, the ensemble feature selection method can get better results than a single feature selection algorithm.

DevOps is a new approach to drive a seamless Application (App) cycle from development to delivery. As a critical part to promote the successful implementation of DevOps, testing can significantly improve team productivity and reliably deliver user experience. However, it is difficult to use traditional testing to cover diverse mobile phones, network environments, operating systems, and so on. Hence, many large companies crowdsource their App testing tasks to workers from open platforms. In crowdsourced testing, test reports submitted by workers may be highly redundant, and their quality may vary sharply. Meanwhile, multi-bug test reports may be submitted, and their root causes are hard to diagnose. Hence, it is a time-consuming and tedious task for developers to manually inspect these test reports. To help developers address the above challenges, we issue the new problem of Fuzzy Clustering Test Reports (FULTER). Aiming to resolve FULTER, a series of barriers need to be overcome. In this study, we propose a new framework named Test Report Fuzzy Clustering Framework (TERFUR) by aggregating redundant and multi-bug test reports into clusters to reduce the number of inspected test reports. First, we construct a filter to remove invalid test reports to break through the invalid barrier . Then, a preprocessor is built to enhance the descriptions of short test reports to break through the uneven barrier . Last, a two-phase merging algorithm is proposed to partition redundant and multi-bug test reports into clusters that can break through the multi-bug barrier . Experimental results over 1,728 test reports from five industrial Apps show that TERFUR can cluster test reports by up to 78.15% in terms of AverageP , 78.41% in terms of AverageR , and 75.82% in terms of AverageF1 and outperform comparative methods by up to 31.69%, 33.06%, and 24.55%, respectively. In addition, the effectiveness of TERFUR is validated in prioritizing test reports for manual inspection.

Driven by new software development processes and testing in clouds, system and integration testing nowadays tends to produce enormous number of alarms. Such test alarms lay an almost unbearable burden on software testing engineers who have to manually analyze the causes of these alarms. The causes are critical because they decide which stakeholders are responsible to fix the bugs detected during the testing. In this paper, we present a novel approach that aims to relieve the burden by automating the procedure. Our approach, called Cause Analysis Model, exploits information retrieval techniques to efficiently infer test alarm causes based on test logs. We have developed a prototype and evaluated our tool on two industrial datasets with more than 14,000 test alarms. Experiments on the two datasets show that our tool achieves an accuracy of 58.3% and 65.8%, respectively, which outperforms the baseline algorithms by up to 13.3%. Our algorithm is also extremely efficient, spending about 0.1s per cause analysis. Due to the attractive experimental results, our industrial partner, a leading information and communication technology company in the world, has deployed the tool and it achieves an average accuracy of 72% after two months of running, nearly three times more accurate than a previous strategy based on regular expressions.

Developers increasingly rely on API tutorials to facilitate software development. However, it remains a challenging task for them to discover relevant API tutorial fragments explaining unfamiliar APIs. Existing supervised approaches suffer from the heavy burden of manually preparing corpus-specific annotated data and features. In this study, we propose a novel unsupervised approach, namely Fragment Recommender for APIs with PageRank and Topic model (FRAPT). FRAPT can well address two main challenges lying in the task and effectively determine relevant tutorial fragments for APIs. In FRAPT, a Fragment Parser is proposed to identify APIs in tutorial fragments and replace ambiguous pronouns and variables with related ontologies and API names, so as to address the pronoun and variable resolution challenge. Then, a Fragment Filter employs a set of non-explanatory detection rules to remove non-explanatory fragments, thus address the non-explanatory fragment identification challenge. Finally, two correlation scores are achieved and aggregated to determine relevant fragments for APIs, by applying both topic model and PageRank algorithm to the retained fragments. Extensive experiments over two publicly open tutorial corpora show that, FRAPT improves the state-of-the-art approach by 8.77% and 12.32% respectively in terms of F-Measure. The effectiveness of key components of FRAPT is also validated.

For large open source projects (e.g., Eclipse, Mozilla), developers usually utilize bug reports to facilitate software maintenance tasks such as fixer assignment. However, there are a large portion of short reports in bug repositories. We find that 78.1% of bug reports only include less than 100 words in Eclipse and require bug fixers to spend more time on resolving them due to limited informative contents. To address this problem, in this paper, we propose a novel approach to enrich bug reports. Concretely, we design a sentence ranking algorithm based on a new textual similarity metric to select the proper contents for bug report enrichment. For the enriched bug reports, we conduct a user study to assess whether the additional sentences can provide further help to fixer assignment. Moreover, we assess whether the enriched versions can improve the performance of automated fixer recommendation. In particular, we perform three popular automated fixer recommendation approaches on the enriched bug reports of Eclipse, Mozilla, and GNU Compiler Collection (GCC). The experimental results show that enriched bug reports improve the average F-measure scores of the automated fixer recommendation approaches by up to 10% for DREX, 13.37% for DRETOM, and 8% for DevRec when top-10 bug fixers are recommended.

During software maintenance, bug reports are widely employed to improve the software project’s quality. A developer often refers to stowed bug reports in a repository for bug resolution. However, this reference process often requires a developer to pursue a substantial amount of textual information in bug reports which is lengthy and tedious. Automatic summarization of bug reports is one way to overcome this problem. Both supervised and unsupervised methods are effectively proposed for the automatic summary generation of bug reports. However, existing methods disregard the significance of duplicate bug reports in summarizing bug reports. In this study, we propose a PageRank-based Summarization Technique (PRST), which utilizes the textual information contained in bug reports and additional information in associated duplicate bug reports. PRST uses three variants of PageRank-based on Vector Space Model (VSM), Jaccard, and WordNet similarity metrics. These variants are utilized to calculate the textual similarity of the sentences between the master bug reports and their duplicates. PRST further trains a regression model and predicts the probability of sentences belonging to the summary. Finally, we combine the values of PageRank and regression model scores to rank the sentences and produce the summary for the master bug reports. In addition, we construct two corpora of bug reports and duplicates, i.e. MBRC and OSCAR. Empirical results suggest that PRST outperforms the state-of-the-art method BRC in terms of Precision, Recall, F-score, and Pyramid Precision. Meanwhile, PRST with WordNet achieves the best results against PRST with VSM and Jaccard.

Developers prefer to utilize third-party libraries when they implement some functionalities and Application Programming Interfaces (APIs) are frequently used by them. Facing an unfamiliar API, developers tend to consult tutorials as learning resources. Unfortunately, the segments explaining a specific API scatter across tutorials. Hence, it remains a challenging issue to find the relevant segments. In this study, we propose a more accurate model to find the exact tutorial fragments explaining APIs. This new model consists of a text classifier with domain specific features. More specifically, we discover two important indicators to complement traditional text based features, namely co-occurrence APIs and knowledge based API extensions. In addition, we incorporate Word2Vec, a semantic similarity metric to enhance the new model. Extensive experiments over two publicly available tutorial datasets show that our new model could find up to 90% fragments explaining APIs and improve the state-of-the-art model by up to 30% in terms of F-measure.

Due to the increasing scale and complexity of software products, software maintenance especially on bug resolution has become a challenging task. Generally in large-scale software programs, developers depend on software artifacts (e.g., bug report, source code and change history) in bug repositories to complete the bug resolution task. However, a mountain of submitted bug reports every day increase the developers' workload. Therefore, ‘How to effectively resolve software defects by utilizing software artifacts?’ becomes a research hotspot in software maintenance. Considerable studies have been done on bug resolution by using multi-techniques, which cover data mining, machine learning and natural language processing. In this paper, we present a literature survey on tasks, challenges and future directions of bug resolution in software maintenance process. Our investigation concerns the most important phases in bug resolution, including bug understanding, bug triage and bug fixing. Moreover, we present the advantages and disadvantages of each study. Finally, based on the investigation and comparison results, we propose the future research directions of bug resolution.

As code search is a frequent developer activity in software development practices, improving the performance of code search is a critical task. In the text retrieval based search techniques employed in the code search, the term mismatch problem is a critical language issue for retrieval effectiveness. By reformulating the queries, query expansion provides effective ways to solve the term mismatch problem. In this paper, we propose Query Expansion based on Crowd Knowledge (QECK), a novel technique to improve the performance of code search algorithms. QECK identifies software-specific expansion words from the high quality pseudo relevance feedback question and answer pairs on Stack Overflow to automatically generate the expansion queries. Furthermore, we incorporate QECK in the classic Rocchio's model, and propose QECK based code search method QECKRocchio. We conduct three experiments to evaluate our QECK technique and investigate QECKRocchio in a large-scale corpus containing real-world code snippets and a question and answer pair collection. The results show that QECK improves the performance of three code search algorithms by up to 64 percent in Precision, and 35 percent in NDCG. Meanwhile, compared with the state-of-the-art query expansion method, the improvement of QECK Rocchio is 22 percent in Precision, and 16 percent in NDCG.

Software companies spend over 45 percent of cost in dealing with software bugs. An inevitable step of fixing bugs is bug triage, which aims to correctly assign a developer to a new bug. To decrease the time cost in manual work, text classification techniques are applied to conduct automatic bug triage. In this paper, we address the problem of data reduction for bug triage, i.e., how to reduce the scale and improve the quality of bug data. We combine instance selection with feature selection to simultaneously reduce data scale on the bug dimension and the word dimension. To determine the order of applying instance selection and feature selection, we extract attributes from historical bug data sets and build a predictive model for a new bug data set. We empirically investigate the performance of data reduction on totally 600,000 bug reports of two large open source projects, namely Eclipse and Mozilla. The results show that our data reduction can effectively reduce the data scale and improve the accuracy of bug triage. Ourwork provides an approach to leveraging techniques on data processing to form reduced and high-quality bug data in software development and maintenance.

In the Google Play store, an introduction page is associated with every mobile application (app) for users to acquire its details, including screenshots, description, reviews, etc. However, it remains a challenge to identify what items influence users most when downloading an app. To explore users’ perspective, we conduct a survey to inquire about this question. The results of survey suggest that the participants pay most attention to the app description which gives users a quick overview of the app. Although there exist some guidelines about how to write a good app description to attract more downloads, it is hard to define a high quality app description. Meanwhile, there is no tool to evaluate the quality of app description. In this paper, we employ the method of crowdsourcing to extract the attributes that affect the app descriptions’ quality. First, we download some app descriptions from Google Play, then invite some participants to rate their quality with the score from one (very poor) to five (very good). The participants are also requested to explain every score’s reasons. By analyzing the reasons, we extract the attributes that the participants consider important during evaluating the quality of app descriptions. Finally, we train the supervised learning models on a sample of 100 app descriptions. In our experiments, the support vector machine model obtains up to 62% accuracy. In addition, we find that the permission, the number of paragraphs and the average number of words in one feature play key roles in defining a good app description.

There has been a growing research trend of applying hyper-heuristics for problem solving, due to their ability of balancing the intensification and the diversification with low level heuristics. Traditionally, the diversification mechanism is mostly realized by perturbing the incumbent solutions to escape from local optima. In this paper, we report our attempt toward providing a new diversification mechanism, which is based on the concept of instance perturbation. In contrast to existing approaches, the proposed mechanism achieves the diversification by perturbing the instance under solving, rather than the solutions. To tackle the challenge of incorporating instance perturbation into hyper-heuristics, we also design a new hyper-heuristic framework HIP-HOP (recursive acronym of HIP-HOP is an instance perturbation-based hyper-heuristic optimization procedure), which employs a grammar guided high level strategy to manipulate the low level heuristics. With the expressive power of the grammar, the constraints, such as the feasibility of the output solution could be easily satisfied. Numerical results and statistical tests over both the Ising spin glass problem and the p -median problem instances show that HIP-HOP is able to achieve promising performances. Furthermore, runtime distribution analysis reveals that, although being relatively slow at the beginning, HIP-HOP is able to achieve competitive solutions once given sufficient time.

Developers build all the software artifacts in development. Existing work has studied the social behavior in software repositories. In one of the most important software repositories, a bug repository, developers create and update bug reports to support software development and maintenance. However, no prior work has considered the priorities of developers in bug repositories. In this paper, we address the problem of the developer prioritization, which aims to rank the contributions of developers. We mainly explore two aspects, namely modeling the developer prioritization in a bug repository and assisting predictive tasks with our model. First, we model how to assign the priorities of developers based on a social network technique. Three problems are investigated, including the developer rankings in products, the evolution over time, and the tolerance of noisy comments. Second, we consider leveraging the developer prioritization to improve three predicted tasks in bug repositories, i.e., bug triage, severity identification, and reopened bug prediction. We empirically investigate the performance of our model and its applications in bug repositories of Eclipse and Mozilla. The results indicate that the developer prioritization can provide the knowledge of developer priorities to assist software tasks, especially the task of bug triage.

Recent years have witnessed the great success of hyper-heuristics applying to numerous real-world applications. Hyper-heuristics raise the generality of search methodologies by manipulating a set of low level heuristics (LLHs) to solve problems, and aim to automate the algorithm design process. However, those LLHs are usually parameterized, which may contradict the domain independent motivation of hyper-heuristics. In this paper, we show how to automatically maintain low level parameters (LLPs) using a hyper-heuristic with LLP adaptation (AD-HH), and exemplify the feasibility of AD-HH by adaptively maintaining the LLPs for two hyper-heuristic models. Furthermore, aiming at tackling the search space expansion due to the LLP adaptation, we apply a heuristic space reduction (SAR) mechanism to improve the AD-HH framework. The integration of the LLP adaptation and the SAR mechanism is able to explore the heuristic space more effectively and efficiently. To evaluate the performance of the proposed algorithms, we choose the p-median problem as a case study. The empirical results show that with the adaptation of the LLPs and the SAR mechanism, the proposed algorithms are able to achieve competitive results over the three heterogeneous classes of benchmark instances.

The Next Release Problem (NRP) aims to optimize customer profits and requirements selection for the software releases. The research on the NRP is restricted by the growing scale of requirements. In this paper, we propose a Backbone-based Multilevel Algorithm (BMA) to address the large scale NRP. In contrast to direct solving approaches, the BMA employs multilevel reductions to downgrade the problem scale and multilevel refinements to construct the final optimal set of customers. In both reductions and refinements, the backbone is built to fix the common part of the optimal customers. Since it is intractable to extract the backbone in practice, the approximate backbone is employed for the instance reduction while the soft backbone is proposed to augment the backbone application. In the experiments, to cope with the lack of open large requirements databases, we propose a method to extract instances from open bug repositories. Experimental results on 15 classic instances and 24 realistic instances demonstrate that the BMA can achieve better solutions on the large scale NRP instances than direct solving approaches. Our work provides a reduction approach for solving large scale problems in search-based requirements engineering.

In this paper, we investigate how to design an efficient heuristic algorithm under the guideline of the backbone and the fat, in the context of the p-median problem. Given a problem instance, the backbone variables are defined as the variables shared by all optimal solutions, and the fat variables are defined as the variables that are absent from every optimal solution. Identification of the backbone (fat) variables is essential for the heuristic algorithms exploiting such structures. Since the existing exact identification method, i.e., limit crossing (LC), is time consuming and sensitive to the upper bounds, it is hard to incorporate LC into heuristic algorithm design. In this paper, we develop the accelerated-LC (ALC)-based multilevel algorithm (ALCMA). In contrast to LC which repeatedly runs the time-consuming Lagrangian relaxation (LR) procedure, ALC is introduced in ALCMA such that LR is performed only once, and every backbone (fat) variable can be determined in O(1) time. Meanwhile, the upper bound sensitivity is eliminated by a dynamic pseudo upper bound mechanism. By combining ALC with the pseudo upper bound, ALCMA can efficiently find high-quality solutions within a series of reduced search spaces. Extensive empirical results demonstrate that ALCMA outperforms existing heuristic algorithms in terms of the average solution quality.

Bug triage is an important step in the process of bug fixing. The goal of bug triage is to assign a new-coming bug to the correct potential developer. The existing bug triage approaches are based on machine learning algorithms, which build classifiers from the training sets of bug reports. In practice, these approaches suffer from the large-scale and low-quality training sets. In this paper, we propose the training set reduction with both feature selection and instance selection techniques for bug triage. We combine feature selection with instance selection to improve the accuracy of bug triage. The feature selection algorithm X2-test, instance selection algorithm Iterative Case Filter, and their combinations are studied in this paper. We evaluate the training set reduction on the bug data of Eclipse. For the training set, 70% words and 50% bug reports are removed after the training set reduction. The experimental results show that the new and small training sets can provide better accuracy than the original one.

The next release problem (NRP) aims to effectively select software requirements in order to acquire maximum customer profits. As an NP-hard problem in software requirement engineering, NRP lacks efficient approximate algorithms for large scale instances. The backbone is a new tool for tackling large scale NP-hard problems in recent years. In this paper, we employ the backbone to design high performance approximate algorithms for large scale NRP instances. Firstly we show that it is NP-hard to obtain the backbone of NRP. Then, we illustrate by fitness landscape analysis that the backbone can be well approximated by the shared common parts of local optimal solutions. Therefore, we propose an approximate backbone based multilevel algorithm (ABMA) to solve large scale NRP instances. This algorithm iteratively explores the search spaces by multilevel reductions and refinements. Experimental results demonstrate that ABMA outperforms existing algorithms on large instances in terms of solution quality and running time.

Recently, pattern matching with flexible gap constraints has attracted extensive attention especially in biological sequence analysis and mining patterns from sequences. An issue is to search Maximal Pattern Matching with Gaps and the One-Off Condition (MPMGOOC). Firstly, we introduce the concept of MPMGOOC. In order to solve the problem, we propose some special concepts of Nettree which is different from a tree in that a node may have more than one parent. Based on Nettree, an algorithm named Heuristic Search Occurrence (HSO) is proposed. The space and time complexities of the algorithm are O(W*m*n) and O(W*n*(n+m*m)) respectively, where m, n, and W are the length of pattern P, sequence S and the maximal gap respectively. The comparison results show that HSO achieves better performance than a state-of-the-art algorithm in most cases of the real-world biological data testing.

In this paper, we proposed a sampling based FANT (S-FANT) for the 3-dimensional assignment problem (AP3). The AP3 is a well-known NP-hard problem, which aims to choose n disjoint triplets with minimum cost from 3 disjoint sets of size n. Due to its intractability, many heuristics have been proposed to obtain near optimal solutions in reasonable time. Since the solution space size of the AP3 is (n!)2, traditional FANT algorithms canpsilat work well for the AP3. In this paper, we showed that, those triplets frequently contained by local optimal solutions are likely to belong to global optimal solutions. Therefore, those triplets can help the ant to converge faster to global optimal solutions. Upon the observation above, the S-FANT consists of two phases. In the sampling phase, a multi-restart scheme is employed to generate local optimal solutions. After that, the pheromone is initialized according to the frequency of triplets appearing in those local optimal solutions. In the FANT phase, a standard FANT algorithm is conducted to explore for better solutions. Extensive experimental results on the standard AP3 benchmark indicated that the new algorithm outperforms the state-of-the-art heuristics in terms of solution quality. Work of this paper not only provides a new efficient heuristic for the AP3, but shows a promising way to design FANT algorithms for those NP-hard problems with large solution space.

The Three-Index Assignment Problem (AP3) is a famous NP-hard problem with wide applications. Since it’s intractable, many heuristics have been proposed to obtain near optimal solutions in reasonable time. In this paper, a new meta-heuristic was proposed for solving the AP3. Firstly, we introduced the conception of muscle (the union of optimal solutions) and proved that it is intractable to obtain the muscle under the assumption that P≠NP. Moreover, we showed that the whole muscle can be approximated by the union of local optimal solutions. Therefore, the Approximate Muscle guided Global Optimization (AMGO) is proposed to solve the AP3. AMGO employs a global optimization strategy to search in a search space reduced by the approximate muscle, which is constructed by a multi-restart scheme. During the global optimization procedure, the running time can be dramatically saved by detecting feasible solutions and extracting poor partial solutions. Extensive experimental results on the standard AP3 benchmark indicated that the new algorithm outperforms the state-of-the-art heuristics in terms of solution quality. Work of this paper not only provides a new meta-heuristic for NP-hard problems, but shows that global optimization can provide promising results in reasonable time, by restricting it to a fairly reduced search space.