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Speedup and simplify pinners and blockers

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To compute dicovered check or pinned pieces we use some bitwise
operators that are not really needed because already accounted for
at the caller site.

For instance in evaluation we compute:

     pos.pinned_pieces(Us) & s

Where pinned_pieces() is:

     st->blockersForKing[c] & pieces(c)

So in this case the & operator with pieces(c) is useless,
given the outer '& s'.

There are many places where we can use the naked blockersForKing[]
instead of the full pinned_pieces() or discovered_check_candidates().

This path is simpler than original and gives around 1% speed up for me.
Also tested for speed by mstembera and snicolet (neutral in both cases).

No functional change.
This commit is contained in:
Marco Costalba
2018-02-27 01:18:33 +01:00
committed by Stéphane Nicolet
parent d438720a1c
commit ad2a0e356e
5 changed files with 30 additions and 31 deletions
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16
src/search.cpp
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@@ -108,6 +108,13 @@ namespace {
void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietsCnt, int bonus);
void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCnt, int bonus);
inline bool gives_check(const Position& pos, Move move) {
Color us = pos.side_to_move();
return type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us))
? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
: pos.gives_check(move);
}
// perft() is our utility to verify move generation. All the leaf nodes up
// to the given depth are generated and counted, and the sum is returned.
template<bool Root>
@@ -823,10 +830,7 @@ moves_loop: // When in check, search starts from here
extension = DEPTH_ZERO;
captureOrPromotion = pos.capture_or_promotion(move);
movedPiece = pos.moved_piece(move);
givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
? pos.check_squares(type_of(movedPiece)) & to_sq(move)
: pos.gives_check(move);
givesCheck = gives_check(pos, move);
moveCountPruning = depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
@@ -1238,9 +1242,7 @@ moves_loop: // When in check, search starts from here
{
assert(is_ok(move));
givesCheck = type_of(move) == NORMAL && !pos.discovered_check_candidates()
? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
: pos.gives_check(move);
givesCheck = gives_check(pos, move);
moveCount++;