RISC-V Global Forum 2020

Code size of embedded applications has been a growing concern recently. While storage becomes cheaper and smaller, developers find creative ways to increase code size by adding features or unnecessary software engineering. Compilers have come a long way in optimizing applications for code size. While most compiler optimization work were focused on application performance, we have seen increase in the code size optimizations in recent years.

In this presentation I'll talk about classical as well as recent compiler optimizations for code size, a few of which I implemented in the LLVM compiler. Some optimizations (hot cold splitting, function entry instrumentation) require collecting data at runtime. I'll provide an overview of how those compiler techniques help reduce code size. I'll also talk about some tips and techniques that help reduce binary size. I'll talk about both gcc and LLVM.