Convolutional Neural Network (CNN) operators, mostly based on mathematical linear computations, are of vital importance to developing CNN-based software. Existing studies reveal that these operators are prone to floating-point precision problems (FPPs). In a CNN-based application, such problems can be propagated and result in catastrophic consequences. Thus, it is highly desired to detect and repair the FPPs in CNN operators. Considering the FPPs in CNN operators are mainly caused by accumulated floating-point errors and diverse floating-point tensors instead of wrong codes or bad implementations, it requires much time cost and is difficult to tackle these FPPs. In this paper, we propose the first method for the automated detection and repair of FPPs in CNN operators from the perspective of floating-point tensors. To generate diverse tensors with floating-point numbers, we design two levels of mutation rules, namely computation-level mutation and input-level mutation, containing a total of five mutation methods. To detect the FPPs caused by the accumulated floating-point errors, our method uses a weight matrix to guide the progressive mutation. To repair the detected FPPs, our method transforms the error-prone floating-point tensors based on the mathematical rewriting of the floating-point linear computational properties without destroying the original computation. Experimental results show that our methods can detect and repair FPPs in CNN operators effectively and efficiently and could reduce 93.32% to 100% of the FPPs in CNN operators. We conduct a case study on six different widely-used CNN models and confirm that the proposed FPP method is generalizable and effective across a variety of tasks and architectures. Our detection and repair method offers an intuitive way to handle FPPs during development, allowing users to continue building and fine-tuning their models without being slowed down by numerical precision errors. We believe that our method could open up a new way to enhance the quality of CNN operators and CNN-based software.

With the wide use of Deep Learning (DL) systems, academy and industry begin to pay attention to their quality. Testing is one of the major methods of quality assurance. However, existing testing techniques focus on the quality of DL models but lacks attention to the core underlying inference engines (i.e., frameworks and libraries). Inspired by the success stories of fuzz testing, we design a graph-based fuzz testing method to improve the quality of DL inference engines. This method is naturally followed by the graph structure of DL models. A novel operator-level coverage criterion based on graph theory is introduced and six different mutations are implemented to generate diversified DL models by exploring combinations of model structures, parameters, and data inputs. The Monte Carlo Tree Search (MCTS) is used to drive DL model generation without a training process. The experimental results show that the MCTS outperforms the random method in boosting operator-level coverage and detecting exceptions. Our method has discovered more than 40 different exceptions in three types of undesired behaviors: model conversion failure, inference failure, output comparison failure. The mutation strategies are useful to generate new valid test inputs, by up to an 8.2% more operator-level coverage on average and 8.6 more exceptions captured.

Deep learning(DL) techniques attract people from various fields with superior performance in making progressive breakthroughs. To ensure the quality of DL techniques, researchers have been working on testing and verification approaches. Some recent studies reveal that the underlying DL operators could cause defects inside a DL model. DL operators work as fundamental components in DL libraries. Library developers still work on practical approaches to ensure the quality of operators they provide. However, the variety of DL operators and the implementation complexity make it challenging to evaluate their quality. Operator testing with limited test cases may fail to reveal hidden defects inside the implementation. Besides, the existing model-to-library testing approach requires extra labor and time cost to identify and locate errors, i.e., developers can only react to the exposed defects. This paper proposes a fuzzing-based operator-level precision testing approach to estimate individual DL operators' precision errors to bridge this gap. Unlike conventional fuzzing techniques, valid shape variable inputs and fine-grained precision error evaluation are implemented. The testing of DL operators is treated as a searching problem to maximize output precision errors. We implement our approach in a tool named Predoo and conduct an experiment on seven DL operators from TensorFlow. The experiment result shows that Predoo can trigger larger precision errors compared to the error threshold declared in the testing scripts from the TensorFlow repository.

Deep learning (DL) libraries reduce the barriers to the DL model construction. In DL libraries, various building blocks are DL operators with different functionality, responsible for processing high-dimensional tensors during training and inference. Thus, the quality of operators could directly impact the quality of models. However, existing DL testing techniques mainly focus on robustness testing of trained neural network models and cannot locate DL operators’ defects. The insufficient test input and undetermined test output in operator testing have become challenging for DL library developers. In this article, we propose an approach, namely Duo, which combines fuzzing techniques and differential testing techniques to generate input and evaluate corresponding output. It implements mutation-based fuzzing to produce tensor inputs by employing nine mutation operators derived from genetic algorithms and differential testing to evaluate outputs’ correctness from multiple operator instances. Duo is implemented in a tool and used to evaluate seven operators from TensorFlow, PyTorch, MNN, and MXNet in an experiment. The result shows that Duo can expose defects of DL operators and realize multidimension evaluation for DL operators from different DL libraries.

It is time consuming to annotate unlabeled remote sensing images. One strategy is taking the labeled remote sensing images from another domain as training samples, and the target remote sensing labels are predicted by supervised classification. However, this may lead to negative transfer due to the distribution difference between the two domains. To address this issue, we propose a novel domain adaptation method through transferring the parameters of extreme learning machine (ELM). The core of this method is learning a transformation to map the target ELM parameters to the source, making the classifier parameters of the target domain maximally aligned with the source. Our method has several advantages which was previously unavailable within a single method: multiclass adaptation through parameter transferring, learning the final classifier and transformation simultaneously, and avoiding negative transfer. We perform experiments on three data sets that indicate improved accuracy and computational advantages compared to baseline approaches.