The ARM LLVM backend has been around for many years and generates high quality code which executes very efficiently. However, LLVM is also increasingly used for resource-constrained embedded systems where code size is more of an issue. Historically, very few code size optimizations have been implemented in LLVM. When optimizing for code size, GCC typically outperforms LLVM significantly.
The goal of this talk is to get a better understanding of why the GCC-generated code is more compact and also about finding out what we need to do on the LLVM side to address those code size deficiencies. As a case study we will have a detailed look at the generated code of an application running on a resource-constrained microcontroller.
