Thread: A big function or not?

I have a program which has a very large function (plus many others), basically it does a long loop inside that function.
will splitting the function in smallers ones improve the overall performance? is doing things in small parts usually a good thing for speed or no? I know it depend on the program, but I am asking for the general rule.
I am thinking that splitting the function will generate a overload to the call stack.
( I will test it, but I need lot of time to rewrite all and would like hear your opinions before).
Thanks

No performance increase. However it is usually better for human comprehension.
If you are worried about stack then yes, perhaps there are too many local variables which could be compartmentalized into smaller functions. Of course if you call function A, which calls function B calling function C, then all the stacked values eat up the same amount of total stack. But if A calls B. Finishes, then calls C, stack use is less.

In a situation where everything is in a long loop, and you introduce function calls, there is a slight performance hit because calling functions take time vs. in-line code. Assuming the compiler doesn't do some cleaver optimizing.

...doesn't do some cleaver optimizing.

You can't beat that "cleaver optimizing", for sure!

If your compiler is good, then it may actually improve performance if you split a large function up into smaller ones. This way the compiler can choose either to inline a function or call it, at its discretion. The advantage here is that (hopefully) the compiler knows which one will provide better performance.

But in truth, unless you know there's a performance problem, don't worry about it. If you do know there's a problem, profile before assuming you know where the source of the problem is. Generally speaking, you want to pick good algorithms and then write them in the most natural way possible, without worrying about microoptimization. That's the compiler's job.

Originally Posted by quzah

OP, don't pay any attention to him. Everything with this dude is a contest. He loses them all, but still, everything's a contest.


Quzah.

Oh yeah, that's an adult way to behave.