Same nested selection

Question

Is there any performance difference between:

size.width += this->font->chars[*ch].advance + this->font->chars[*ch].offset.x;

and

char_data *chars = this->font->chars;
while(...) {
   size.width += chars[*ch].advance + chars[*ch].offset.x;
}

In first example are always read vars( this->font, font->chars ) within loop, or they are cached?

Answer 1

That would depend on your compiler and optimization settings. At the most basic level, the first one will be slower because you're doing extra dereferencing and access operations. But in reality, the optimizer can identify these repetitions and eliminate them.

To definitively answer this, you should run a test and compare the two to see if there is a statistically significant difference in running times.