Optimizing the LLVM ELF linker for a distributed compilation environment : Concurrent Linking with LLVM LLD

Sammanfattning: Modern build systems that build large software projects often utilize a distributed compiler, allowing the compilation of object files to be parallelized over multiple machines. These build systems are often not able to fully utilize all the resources available on all machines. As linking is not part of this distributed process, the unused resources could be used to perform linking instead, reducing the total build time. However, linking is often performed at the end of the build process, thus not being able to access the previously unused resources. In this thesis project, a linker that runs concurrently with the compilation process of the build system is designed, implemented, and evaluated . As the compilation process produces an object file, the linker performs a partial link using this file. The link is finalized at the end of the build, not unlike a traditional linker. The results show that the total build time is reduced when using the new linker in a build system utilizing a distributed compiler. In some cases, the time spent linking at the end of the build system is reduced over 50 percent when compared to the reference linker.