c - Get Assembly code after every optimization GCC makes?

Question

From Optimization Compiler on Wikipedia,

Compiler optimization is generally implemented using a sequence of optimizing transformations, algorithms which take a program and transform it to produce a semantically equivalent output program that uses fewer resources.

and GCC has a lot of optimization options.

I'd like to study the generated assembly (the one -S gives) after each optimization GCC performs when compiling with different flags like -O1, -O2, -O3, etc.

How can I do this?

Edit: My input will be C code.

Answer 1

Intermediate representation can be saved to files using -fdump-tree-all switch.

There are more fine-grained -fdump switches awailable.

See gcc manual for details.

To be able to read these representations, take a look into GCC internals manual.