If you want to know what GCC is outputting, you need to learn a hell of a lot more than just x86 assembly. You're going to have to do quite a bit of study of compiler theory. Run objdump on some non-trivial C program and the direct flow of logic will not likely directly resemble the C you wrote.
You don't need to study compiler theory to understand the kind of code the compiler will output. That's very easy to reason about, and much harder to implement.
Knowing x86 assembly is more than enough to reason backwards from assembly to the C that generated it.
