Can different optimization levels lead to functionally different code?

Question

I am curious about the liberties that a compiler has when optimizing. Let\'s limit this question to GCC and C/C++ (any version, any flavour of standard):

Is it possi

Answer 1

same source code like

before enable -finline-small-functions and after enable -finline-small-functions

-finline-small-functions can be enabled in -O2/-O3