Link Time Optimization
Link Time Optimization (LTO) is a compiler optimization technique that performs whole-program analysis and optimization during the linking phase of compilation. It allows the compiler to see across multiple translation units (source files) to optimize code globally, such as inlining functions across files, removing unused code, and improving inter-procedural optimizations. This can lead to smaller binary sizes and faster execution compared to traditional per-file compilation.
Developers should use LTO when building performance-critical applications, such as game engines, high-frequency trading systems, or embedded software, where every bit of speed and size matters. It is particularly beneficial for large codebases with many source files, as it enables optimizations that are impossible during single-file compilation, like cross-module inlining and dead code elimination across the entire program.