Selecting gcc optimisation flags equivalent to -O1

Question

I have small program that performs much better when compiled with -O1 as opposed to no optimisation. I am interested in knowing what optimisation(s) done by the com

Answer 1

How about using -S option to check the produced assembler?

From two experiments using also "my_program.c" it seems, that -O0 option disables all optimizations regardless of the long list of suggested algorithms.