X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.cpp;h=638f81757d2af94d72c9b0c6739ab1d191d2c6f5;hp=f4f475fb18baa75d7cdb4535723d455daf14be4f;hb=35ada63174bbec6289d6dea6d3cfc5b5f14d1d27;hpb=c8af7a867e91e833f76b564f6f430c96829760bc

diff --git a/src/movepick.cpp b/src/movepick.cpp
index f4f475fb..638f8175 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -94,8 +94,16 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
   else if (d == Depth(0))
       phasePtr = QsearchWithChecksPhaseTable;
   else
+  {
       phasePtr = QsearchWithoutChecksPhaseTable;
 
+      // Skip TT move if is not a capture or a promotion, this avoids
+      // qsearch tree explosion due to a possible perpetual check or
+      // similar rare cases when TT table is full.
+      if (ttm != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm))
+          searchTT = ttMoves[0].move = MOVE_NONE;
+  }
+
   phasePtr += !searchTT - 1;
   go_next_phase();
 }
@@ -141,7 +149,7 @@ void MovePicker::go_next_phase() {
   case PH_EVASIONS:
       assert(pos.is_check());
       lastMove = generate_evasions(pos, moves);
-      score_evasions();
+      score_evasions_or_checks();
       return;
 
   case PH_QCAPTURES:
@@ -150,8 +158,8 @@ void MovePicker::go_next_phase() {
       return;
 
   case PH_QCHECKS:
-      // Perhaps we should order moves move here?  FIXME
       lastMove = generate_non_capture_checks(pos, moves);
+      score_evasions_or_checks();
       return;
 
   case PH_STOP:
@@ -224,7 +232,7 @@ void MovePicker::score_noncaptures() {
   }
 }
 
-void MovePicker::score_evasions() {
+void MovePicker::score_evasions_or_checks() {
   // Try good captures ordered by MVV/LVA, then non-captures if
   // destination square is not under attack, ordered by history
   // value, and at the end bad-captures and non-captures with a
@@ -232,6 +240,10 @@ void MovePicker::score_evasions() {
   Move m;
   int seeScore;
 
+  // Skip if we don't have at least two moves to order
+  if (lastMove < moves + 2)
+      return;
+
   for (MoveStack* cur = moves; cur != lastMove; cur++)
   {
       m = cur->move;
@@ -250,6 +262,8 @@ void MovePicker::score_evasions() {
 /// are no more moves left.
 /// It picks the move with the biggest score from a list of generated moves taking
 /// care not to return the tt move if has already been searched previously.
+/// Note that this function is not thread safe so should be lock protected by
+/// caller when accessed through a shared MovePicker object.
 
 Move MovePicker::get_next_move() {
 
@@ -339,17 +353,3 @@ Move MovePicker::get_next_move() {
   }
 }
 
-/// A variant of get_next_move() which takes a lock as a parameter, used to
-/// prevent multiple threads from picking the same move at a split point.
-
-Move MovePicker::get_next_move(Lock &lock) {
-
-   lock_grab(&lock);
-
-   // Note that it is safe to call many times
-   // get_next_move() when phase == PH_STOP
-   Move m = get_next_move();
-
-   lock_release(&lock);
-   return m;
-}