LLVM Pass

Compilers, regardless of type or name, have three phases: Frontend, Optimizer, Backend. The LLVM Pass is a part of the optimizer step. Passes can be seen as the "workers" in the LLVM system, and can be categorized into two different categories analytical passes and transformational passes. However, both archetypes share the same core: parsing the LLVM Intermediate Representation. The scope between passes differs, with some workers looking for different parts of the code at varying levels of granularity:

1. Module Passes: Looks at the entire program
2. Function Passes: Focuses on one function at a time. Workers typically run in parallel.
3. Loop Passes: Targets Loop structures specifically
4. Call Graph Passes: Analyzes relationships between functions

All of this is orchestrated by the LLVM Pass Manager, which is responsible for scheduling, dependency management, and handling efficiency. Implementation of LLVM passes is a well-studied topic and has been done to support popular pieces of software like ASan