static关键字是否可以提高性能？

Question

I appreciate that this is a micro-optimization, but I am interested in whether declaring either a function or member variable as static provides any performance increase compared to a non- static implementation?

I remember reading that const can be used for compilers to optimize, so it made me wonder whether static had any similar advantages.

Answer 1

Considering that static and non- static variables have extremely different semantics, whether or not you can declare static really has nothing to do with performance.

Also, cache and other issues might well mean "no".

Answer 2

it could be for data, if construction takes a long time (eg a precomputed buffer or something read from disk). often, this is only ideal when the data is immutable.

Answer 3

@DeadMG already pointed out that changing a member variable to static would completely change the semantics, the same applies to a static function.

In general the answer is no, static doesn't help performance ( and neither does const ) but one way that static can help is in an ELF shared library, where a static function isn't externally visible and so calls to it don't need to go through the procedure linkage table , which gives a small performance benefit which can be worth considering when writing code for shared libraries.