Software engineering, fundamental to modern technological advancement, profoundly influences various aspects of society by enhancing efficiency, accessibility, and security. This discipline involves systematically applying engineering principles to software systems' design, development, testing, and maintenance. Innovations in software engineering have revolutionized industries such as communication, finance, healthcare, and education, democratizing access to information and connecting global communities. As software systems become increasingly complex, the need for efficient, secure, and reliable software analysis tools becomes paramount.

The thesis focuses on improving the actionability and scalability of software analysis by integrating machine learning (ML) techniques. Traditional static analysis tools often struggle with large codebases, leading to high false positive rates and high computational costs. Machine learning, particularly deep learning architectures like Transformers, offers a promising solution by capturing long-range dependencies in code and learning hierarchical representations. This capability enables ML models to automate tasks such as bug detection, source code summarization, and program repair, providing developers with actionable insights and improving overall productivity and code quality.

A significant contribution of this thesis is the development of ML-based techniques for type inference in Python and call graph pruning. An ML-based type inference approach, namely Type4Py, was proposed, which accurately predicts type annotations for Python code, enhancing code quality and reducing runtime errors. ML models with conservative pruning strategies were proposed for call graph pruning, which learns from dynamic traces obtained by executing programs to identify and eliminate false edges, thereby minimizing false positives and improving precision. Additionally, the thesis explores the application of call graphs in vulnerability analysis, demonstrating that granular assessments provide more accurate and actionable insights than more straightforward, dependency-level analyses.

In summary, this thesis advances the field of software analysis by harnessing machine learning to address two important issues related to the actionability and scalability of software analysis tools. The proposed ML-driven tools and techniques enhance the precision and reliability of software analysis and support developers in maintaining robust, secure, and maintainable software systems. These contributions pave the way for future research in applying ML techniques to various aspects of software engineering, promising further improvements in software development practices.@en

In light of the growing interest in type inference research for Python, both researchers and practitioners require a standardized process to assess the performance of various type inference techniques. This paper introduces TypeEvalPy, a comprehensive microbenchmarking framework for evaluating type inference tools. Type- EvalPy contains 154 code snippets with 845 type annotations across 18 categories that target various Python features. The framework manages the execution of containerized tools, transforms inferred types into a standardized format, and produces meaningful metrics for assessment. Through our analysis, we compare the performance of six type inference tools, highlighting their strengths and limitations. Our findings provide a foundation for further research and optimization in the domain of Python type inference.

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Reusing software libraries is a pillar of modern software engineering. In 2022, the average Java application depends on 40 third-party libraries. Relying on such libraries exposes a project to potential vulnerabilities and may put an application and its users at risk. Unfortunately, research on software ecosystems has shown that the number of projects that are affected by such vulnerabilities is rising. Previous investigations usually reason about dependencies on the dependency level, but we believe that this highly inflates the actual number of affected projects. In this work, we study the effect of transitivity and granularity on vulnerability propagation in the Maven ecosystem. In our research methodology, we gather a large dataset of 3M recent Maven packages. We obtain the full transitive set of dependencies for this dataset, construct whole-program call graphs, and perform reachability analysis. This approach allows us to identify Maven packages that are actually affected by using vulnerable dependencies. Our empirical results show that: (1) about 1/3 of packages in our dataset are identified as vulnerable if and only if all the transitive dependencies are considered. (2) less than 1% of packages have a reachable call path to vulnerable code in their dependencies, which is far lower than that of a naive dependency-based analysis. (3) limiting the depth of the resolved dependency tree might be a useful technique to reduce computation time for expensive fine-grained (vulnerability) analysis. We discuss the implications of our work and provide actionable insights for researchers and practitioners.@en

Dynamic languages, such as Python and Javascript, trade static typing for developer flexibility and productivity. Lack of static typing can cause run-time exceptions and is a major factor for weak IDE support. To alleviate these issues, PEP 484 introduced optional type annotations for Python. As retrofitting types to existing code-bases is error-prone and laborious, machine learning (ML)-based approaches have been proposed to enable automatic type infer-ence based on existing, partially annotated codebases. However, previous ML-based approaches are trained and evaluated on human-provided type annotations, which might not always be sound, and hence this may limit the practicality for real-world usage. In this paper, we present TYPE4Py, a deep similarity learning-based hier-archical neural network model. It learns to discriminate between similar and dissimilar types in a high-dimensional space, which results in clusters of types. Likely types for arguments, variables, and return values can then be inferred through the nearest neigh-bor search. Unlike previous work, we trained and evaluated our model on a type-checked dataset and used mean reciprocal rank (MRR) to reflect the performance perceived by users. The obtained results show that TYPE4Py achieves an MRR of 77.1 %, which is a substantial improvement of 8.1% and 16.7% over the state-of-the-art approaches Typilus and Typewriter, respectively. Finally, to aid developers with retrofitting types, we released a Visual Stu-dio Code extension, which uses TYPE4Py to provide ML-based type auto-completion for Python.

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In this paper, we present ManyTypes4Py, a large Python dataset for machine learning (ML)-based type inference. The dataset contains a total of 5, 382 Python projects with more than 869K type annotations. Duplicate source code files were removed to eliminate the negative effect of the duplication bias. To facilitate training and evaluation of ML models, the dataset was split into training, validation and test sets by files. To extract type information from abstract syntax trees (ASTs), a light-weight static analyzer pipeline is developed and accompanied with the dataset. Using this pipeline, the collected Python projects were analyzed and the results of the AST analysis were stored in JSON-formatted files. The ManyTypes4Py dataset is shared on zenodo and its tools are publicly available on GitHub.

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Among the extensions of twin support vector machine (TSVM), some scholars have utilized K-nearest neighbor (KNN) graph to enhance TSVM’s classification accuracy. However, these KNN-based TSVM classifiers have two major issues such as high computational cost and overfitting. In order to address these issues, this paper presents an enhanced regularized K-nearest neighbor-based twin support vector machine (RKNN-TSVM). It has three additional advantages: (1) Weight is given to each sample by considering the distance from its nearest neighbors. This further reduces the effect of noise and outliers on the output model. (2) An extra stabilizer term was added to each objective function. As a result, the learning rules of the proposed method are stable. (3) To reduce the computational cost of finding KNNs for all the samples, location difference of multiple distances-based K-nearest neighbors algorithm (LDMDBA) was embedded into the learning process of the proposed method. The extensive experimental results on several synthetic and benchmark datasets show the effectiveness of our proposed RKNN-TSVM in both classification accuracy and computational time. Moreover, the largest speedup in the proposed method reaches to 14 times.

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