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Remove sorting optimization for many zeroes

With negative history we don't have anymore a
lot of zeroes to score, so just split moves in
positives and non-positives sets.

Speed up is almost zero, we cannot test speed directly
because node count changed due to reorder, but I have
verified sorting is correct. With a profiler I have
seen we gain a little in sort_moves() and lose a little
in insertion_sort(), so the net effect is almost zero,
but code is simpler.

No real change, just move reordering.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-02-05 17:37:33 +01:00
parent 321f6d1d19
commit b0858877ae

View file

@ -86,8 +86,8 @@ inline void insertion_sort(T* firstMove, T* lastMove)
}
}
// Our dedicated sort in range [firstMove, lastMove), it is well
// tuned for non-captures where we have a lot of zero scored moves.
// Our dedicated sort in range [firstMove, lastMove), first splits
// positive scores from ramining then order seaprately the two sets.
template<typename T>
inline void sort_moves(T* firstMove, T* lastMove)
{
@ -114,28 +114,8 @@ inline void sort_moves(T* firstMove, T* lastMove)
} while (p != d);
// Sort positives
// Sort positives and non-positives separately
insertion_sort<T>(firstMove, p);
d = lastMove;
p--;
// Split zero vs negatives
do {
while ((++p)->score == 0);
if (p != d)
{
while (--d != p && d->score < 0);
tmp = *p;
*p = *d;
*d = tmp;
}
} while (p != d);
// Sort negatives
insertion_sort<T>(p, lastMove);
}