How do you compile C to assembly and examine the output?

Use gcc -S to stop after the compile stage and produce a .s assembly file — add -O1/-O2 to see optimized code.

This is the everyday workflow for understanding how C maps to machine instructions, and the basis of tools like Compiler Explorer.

gcc -S program.c                 # unoptimized assembly
gcc -S -O1 program.c             # optimized
gcc -S -O2 -fverbose-asm prog.c  # annotate which C variable each line uses
gcc -S -masm=intel program.c     # Intel syntax

Compiler Explorer (godbolt.org) lets you do this interactively in a browser and compare compilers and flags side by side — invaluable for learning.

Reading the output:

1. Labels ending in : are function names or jump targets.
2. .L-prefixed labels are compiler-generated locals.
3. Directives like .section, .globl, .type are instructions to the assembler, not real code.
4. Focus on the instructions between a function label and its ret.

Tip: add -fno-asynchronous-unwind-tables to strip the .cfi_* directives and get much cleaner output when you're just trying to read the logic.