rohitgeek wrote:
mentioned by Ian too, i get what i expect. But why does optimizer does so?
because it can with respect to the semantics of the compiled language. Your statements assign values to local variables. There is no side effect. The values you assign are not used later on. So they are completely useless. Computing them or not won't change the semantics of your program. At all. It's cool that gcc finds that out for cases where your code actually does something, where optimization is useful. No?
Where is the assembly or data gone when doing the earlier way, because if we
You write programs in C, not in assembly language. The C compiler can compile the way it wants as long as the C semantics is respected.
put some data into registers and done some manipulations, then where are
This is what you don't understand I guess. Your program doesn't "put some data into registers and [does] some manipulations." Your program assigns values to C variables. This is another world. C is not assembly language. So in short, as others said, if you want the code to stay there after optimization, be sure it does real stuff, like returning the computed value. The computed value has to "escape" the local scope for it to be "respected" by the optimization. My .2 euros.
