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Micro optimize copy of new state in do_move()

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Instead of copying all, copy only the fields that
are updated incrementally, not the ones that are
recalcuated form scratch anyway.

This reduces copy overhead of 30%.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-03-02 17:32:30 +01:00
parent c02613860a
commit 772a37cd54
2 changed files with 14 additions and 6 deletions
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15
src/position.cpp
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@@ -707,10 +707,17 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
assert(is_ok());
assert(move_is_ok(m));
// Copy some fields of old state to our new StateInfo object (except the
// captured piece, which is taken care of later) and switch state pointer
// to point to the new, ready to be updated, state.
newSt = *st;
// Copy some fields of old state to our new StateInfo object except the
// ones which are recalculated from scratch anyway, then switch our state
// pointer to point to the new, ready to be updated, state.
struct ReducedStateInfo {
Key key, pawnKey, materialKey;
int castleRights, rule50;
Square epSquare;
Value mgValue, egValue;
};
memcpy(&newSt, st, sizeof(ReducedStateInfo));
newSt.capture = NO_PIECE_TYPE;
newSt.previous = st;
st = &newSt;