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Introduce MovePicker::isBadCapture() and use in probcut

Browse source 
Small functional change due to the fact that now we skip
probcut on evasions.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-05-21 10:40:36 +01:00
parent 13d8af1852
commit 3ef4fdeaa0
3 changed files with 10 additions and 12 deletions
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1
src/movepick.cpp
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@ -46,6 +46,7 @@ namespace {
const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP };
}
bool MovePicker::isBadCapture() const { return phase == PH_BAD_CAPTURES; }
/// Constructor for the MovePicker class. Apart from the position for which
/// it is asked to pick legal moves, MovePicker also wants some information

1
src/movepick.h
View file

@ -43,6 +43,7 @@ public:
MovePicker(const Position&, Move, Depth, const History&, SearchStack*, Value);
MovePicker(const Position&, Move, Depth, const History&);
Move get_next_move();
bool isBadCapture() const;
private:
void score_captures();

20
src/search.cpp
View file

@ -681,7 +681,7 @@ namespace {
ValueType vt;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous, isBadCap;
bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
int moveCount = 0, playedMoveCount = 0;
int threadID = pos.thread();
SplitPoint* sp = NULL;
@ -1023,16 +1023,6 @@ split_point_start: // At split points actual search starts from here
}
}
// Bad capture detection. Will be used by prob-cut search
isBadCap = depth >= 3 * ONE_PLY
&& depth < 8 * ONE_PLY
&& captureOrPromotion
&& move != ttMove
&& !dangerous
&& !move_is_promotion(move)
&& abs(alpha) < VALUE_MATE_IN_PLY_MAX
&& pos.see_sign(move) < 0;
// Step 13. Make the move
pos.do_move(move, st, ci, givesCheck);
@ -1076,7 +1066,13 @@ split_point_start: // At split points actual search starts from here
// Probcut search for bad captures. If a reduced search returns a value
// very below beta then we can (almost) safely prune the bad capture.
if (isBadCap)
if ( depth >= 3 * ONE_PLY
&& depth < 8 * ONE_PLY
&& mp.isBadCapture()
&& move != ttMove
&& !dangerous
&& !move_is_promotion(move)
&& abs(alpha) < VALUE_MATE_IN_PLY_MAX)
{
ss->reduction = 3 * ONE_PLY;
Value rAlpha = alpha - 300;