Description

This project aims to implement a GlobalModuleIndex [1],[2], which is expected to speed up ROOT’s [3] startup time two times. ROOT has its own C++ interpreter called Cling [4] for getting the reflection information.

We have been implementing C++ modules support in ROOT for the last few years, and we have recently reached the production level. However, there is still a room for optimization, and one of the possible solutions could be the implementation of GlobalModuleIndex. It is a mechanism to create the table of symbols and PCM names, so that ROOT will be able to load a corresponding library when a symbol lookup failed. This project will give the selected student an opportunity to contribute to two large and widely-used open source projects: ROOT and Clang/LLVM [5]. Moreover, the student will get a deep knowledge of C++ compiler and interpreter technology throughout this project.

Task ideas

• Implement a lazy loading of PCMs in GlobalModuleIndex.
• Instantiate GlobalModuleIndex class in ROOT.
• Register identifiers and modules of ROOT.
• Implement a callback in Cling, which gets a callback when an identifier lookup was failed.
• Deprecate startup modules loading step in ROOT, test a new implementation and provide performance measurements.

Expected results

Implement GlobalModuleIndex in ROOT/Cling, provide a performance tuning for preloading of PCMs.

Desirable Skills

• Patience
• C++ knowledge
• Interest in Compiler technology

Mentors

• Yuka Takahashi
• Oksana Shadura
• Vassil Vassilev

Links

1. GlobalModuleIndex
2. Modules
3. ROOT
4. Cling
5. Clang/LLVM

Corresponding Project

• ROOT

Participating Organizations

• CERN
• UNL

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