From Source Code to Binary: What Does GCC Actually Do?

Short summary

GCC transforms C code through four stages—preprocessing, compilation, assembly, and linking—producing an ELF binary with compiler-generated functions and optimizations. The System V AMD64 ABI convention routes the first six function arguments through specific CPU registers before using the stack, enabling efficient calling. The compiler actively optimizes code, as shown by its replacement of printf with the more efficient puts function.

• •GCC orchestrates four sequential stages: preprocessing, compilation, assembly, and linking to convert human-readable C code into machine executable binaries
• •ELF binaries contain compiler-generated functions (_start, __libc_start_main) and sections (.init, .fini, .plt, .text) that manage program lifecycle and dynamic linking
• •System V AMD64 ABI uses CPU registers (rdi, rsi, rdx, rcx, r8, r9) for first six function arguments, optimizing for speed versus slower stack operations

Generated with AI, which can make mistakes.