Limit std::sort comparisons on small list

[Paolo Carlini]

Hi,

On 10/03/2013 10:04 PM, François Dumont wrote:
> So no impact on sort because the number of elements involved is too 
> important. Good, even if limited, impact on stable_sort because it 
> reduces the number of comparison by about 0.5% in the random case. I 
> have added a test to check that on small number of elements it has the 
> expected impact, only 1 comparison when 2 elements in the array.
Thanks for your help on this. While we wait for comments from Chris, 
Marc and other interested people, I have a rather simple-minded question 
for you: how would you explain that the number of comparisons for the 
sort performance tests remains *exactly* the same, while we know that 
the change helps for 2 elements, avoiding a comparison? Isn't navely 
weird that a similar situation *never* happens for the performance 
tests? Surely it does happen if we change the random seed of the random 
variant, at least an handful of times?!?

Thanks again,
Paolo.