The security of an app is a crucial concern for developers. Without proper protection mechanisms, attackers can easily use reverse engineering to analyze the application's structure and functionality, leading to actions that compromise the developer's interests, such as bypassing paid features, stealing sensitive data, or even injecting malicious code for distribution. This talk will explore how compilers can be leveraged to protect app code and increase the difficulty of reverse engineering. Attendees will gain insights into modern compiler design principles, fundamental knowledge of Clang/LLVM, code protection techniques implementable in compilers, open-source solutions, and experiences and challenges in developing compiler-based protection mechanisms at ICEshell.