What is the term for this type of refactoring

Question

I am sure there is a term for the following bit of refactoring, but I can't remember it and my Google-fu is failing me!

The refactor moves if statements to where they are going to have most impact, for example changing this

$test = someFunctionThatReturnsABool();
for($x = 0; $x < 10000; $x++) {
    if ($test) { 
        echo $x; 
    }
}

To this

$test = someFunctionThatReturnsABool();
if ($test) {
    for($x = 0; $x < 10000; $x++) {
        echo $x; 
    }
}

Answer 1

This is loop-invariant code motion. A good compiler should do it on its own.

Answer 2

This is also called hoisting or scalar promotion. See here .

Answer 3

Looks like a variant of Remove Control Flag (pp 245 of Fowler's Refactoring)

A PHP example can be found on DZone.

Answer 4

I don't think such a refactoring exists.

So, it would be hard to find it amongst ''lists of refactorings''.

I'd class that example as an optimisation not a refactoring.

Refactoring, to me, is changing the code to improve its understandability without affecting its behaviour.

Optimisation, to me, is changing the code to improve performance.

Since optimised code tends to be less easy to understand. The two practices tend to work against each other.