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d4b9ee0)
the order of elements returned by std::partition is implementation defined (since not stable) and could depend on the version of libstdc++ linked.
As std::stable_partition was tested to be too slow (http://tests.stockfishchess.org/tests/view/
585cdfd00ebc5903140c6082).
Instead combine partition with our custom implementation of insert_sort, which fixes this issue.
Implementation based on a patch by mstembera (http://tests.stockfishchess.org/tests/view/
58d4d3460ebc59035df3315c), which suggests some benefit by itself.
Higher depth moves are all sorted (INT_MIN version), as in current master.
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 33116 W: 6161 L: 6061 D: 20894
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 88703 W: 11572 L: 11540 D: 65591
Bench:
6256522
Closes #1058
Closes #1065
QSEARCH_RECAPTURES, QRECAPTURES
};
QSEARCH_RECAPTURES, QRECAPTURES
};
- // Our insertion sort, which is guaranteed to be stable, as it should be
- void insertion_sort(ExtMove* begin, ExtMove* end)
+ // An insertion sort, which sorts moves in descending order up to and including a given limit.
+ // The order of moves smaller than the limit is left unspecified.
+ // To keep the implementation simple, *begin is always included in the list of sorted moves.
+ void partial_insertion_sort(ExtMove* begin, ExtMove* end, Value limit)
- ExtMove tmp, *p, *q;
-
- for (p = begin + 1; p < end; ++p)
- {
- tmp = *p;
- for (q = p; q != begin && *(q-1) < tmp; --q)
- *q = *(q-1);
- *q = tmp;
- }
+ for (ExtMove *sortedEnd = begin + 1, *p = begin + 1; p < end; ++p)
+ if (p->value >= limit)
+ {
+ ExtMove tmp = *p, *q;
+ *p = *sortedEnd;
+ for (q = sortedEnd; q != begin && *(q-1) < tmp; --q)
+ *q = *(q-1);
+ *q = tmp;
+ ++sortedEnd;
+ }
}
// pick_best() finds the best move in the range (begin, end) and moves it to
}
// pick_best() finds the best move in the range (begin, end) and moves it to
cur = endBadCaptures;
endMoves = generate<QUIETS>(pos, cur);
score<QUIETS>();
cur = endBadCaptures;
endMoves = generate<QUIETS>(pos, cur);
score<QUIETS>();
- if (depth < 3 * ONE_PLY)
- {
- ExtMove* goodQuiet = std::partition(cur, endMoves, [](const ExtMove& m)
- { return m.value > VALUE_ZERO; });
- insertion_sort(cur, goodQuiet);
- } else
- insertion_sort(cur, endMoves);
+
+ partial_insertion_sort(cur, endMoves,
+ depth < 3 * ONE_PLY ? VALUE_ZERO : Value(INT_MIN));