ОЦІНКА ТА ЗАБЕЗПЕЧЕННЯ ЯКОСТІ МІГРОВАНОГО ABAP-КОДУ ЗА ДОПОМОГОЮ ІНТЕГРАЛЬНОЇ МЕТРИКИ ТА МОДЕЛЕЙ ГЕНЕРАТИВНОГО ШТУЧНОГО ІНТЕЛЕКТУ

Context. Migration automation of legacy custom code when transitioning to the new version of the SAP S/4HANA system using large language models (LLMs) is a promising option. However, the generated code quality assessment remains an unresolved issue, since existing approaches utilize fragmented metrics which do not allow for a comprehensive software code quality assessment and assurance for further use without additional revision.Objective. The objective of this work is to improve the efficiency of the process of intelligent reengineering of a computer system based on the method of comprehensive assessment and quality assurance of migrated ABAP custom code.Method. The developed method is based on two key components. The Integral ABAP Quality Score (IAQS) comprehensively takes into account the syntactic, functional, and semantic characteristics of the code and is based on the provisions of the international software quality standards ISO/IEC 25010, ISO/IEC 25040, as well as the theory of composite indicators. The threestage approach to LLM fine-tuning (Qwen 2.5 Coder 14B) includes continuous pre-training (CPT), parameter-efficient fine-tuning (PEFT), and alignment based on preferences using the ORPO algorithm. At the same time, the use of the developed IAQS metric to form a set of preference data at the alignment stage creates a mechanism for controlled improvement, namely, it determines the direction of LLM adaptation.Results. The results of experimental studies demonstrate that the implementation of the developed method allows improving both individual indicators of software code quality and the integral metric of IAQS quality assessment as a whole. The final model, trained on the basis of the proposed three-stage approach, achieved a high IAQS value (0.756), which demonstrates a significant improvement compared to the baseline model (0.117).Conclusions. The study presents a new problem-oriented approach to automated migration of ABAP code during intelligent reengineering of computer systems. The proposed IAQS integral metric is the basis for creating a formalized and objective system for evaluating the quality of software generated by LLM in the context of legacy custom code migrating. It has been demonstrated that consistent fine-tuning of LLM based on a three-stage approach using IAQS provides a significant improvement in the generated software code integral quality indicator.