Revert "null move reorder" series

Does not seem to improve on the standard, latest results
from Joona after 2040 games are negative:

Orig - Mod: 454 - 424 - 1162

And is more or less the same I got few days ago.

So revert for now.

Verified same functionality of 595a90dfd

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/movepick.cpp b/src/movepick.cpp
index a9cc245dcb570702d316f4736152d550457fbef2..6b7483eb99c0a782f529b71cbb950e8aaa7a791a 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -40,9 +40,7 @@
 namespace {
 
   CACHE_LINE_ALIGNMENT
-  const MovegenPhaseT MainSearchPhaseTable[] = { PH_NULL_MOVE, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
-  const MovegenPhaseT MainSearchNoNullPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
-  const MovegenPhaseT LowSearchPhaseTable[]  = { PH_TT_MOVES, PH_NULL_MOVE, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
+  const MovegenPhaseT MainSearchPhaseTable[] = { PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
   const MovegenPhaseT EvasionsPhaseTable[] = { PH_EVASIONS, PH_STOP};
   const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
   const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
@@ -62,7 +60,7 @@ namespace {
 /// move ordering is at the current node.
 
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
-                       const History& h, SearchStack* ss, bool useNullMove) : pos(p), H(h) {
+                       const History& h, SearchStack* ss) : pos(p), H(h) {
   ttMoves[0].move = ttm;
   if (ss)
   {
@@ -82,10 +80,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
 
   if (p.is_check())
       phasePtr = EvasionsPhaseTable;
-  else if (d >= Depth(3 * OnePly))
-      phasePtr = useNullMove ? MainSearchPhaseTable : MainSearchNoNullPhaseTable;
   else if (d > Depth(0))
-      phasePtr = useNullMove ? LowSearchPhaseTable : MainSearchNoNullPhaseTable;
+      phasePtr = MainSearchPhaseTable;
   else if (d == Depth(0))
       phasePtr = QsearchWithChecksPhaseTable;
   else
@@ -105,9 +101,6 @@ void MovePicker::go_next_phase() {
   phase = *(++phasePtr);
   switch (phase) {
 
-  case PH_NULL_MOVE:
-      return;
-
   case PH_TT_MOVES:
       curMove = ttMoves;
       lastMove = curMove + 2;
@@ -258,10 +251,6 @@ Move MovePicker::get_next_move() {
   {
       switch (phase) {
 
-      case PH_NULL_MOVE:
-          go_next_phase();
-          return MOVE_NULL;
-
       case PH_TT_MOVES:
           while (curMove != lastMove)
           {

diff --git a/src/movepick.h b/src/movepick.h
index b31d9dd2d48dafbdc3fc1f985e58189f645f5404..147d5d0b0a666915031f687a82e0d858f7aad5ce 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -38,7 +38,6 @@
 struct SearchStack;
 
 enum MovegenPhase {
-  PH_NULL_MOVE,      // Null move
   PH_TT_MOVES,       // Transposition table move and mate killer
   PH_GOOD_CAPTURES,  // Queen promotions and captures with SEE values >= 0
   PH_KILLERS,        // Killer moves from the current ply
@@ -65,7 +64,7 @@ class MovePicker {
   MovePicker& operator=(const MovePicker&); // silence a warning under MSVC
 
 public:
-  MovePicker(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss = NULL, bool useNullMove = false);
+  MovePicker(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss = NULL);
   Move get_next_move();
   Move get_next_move(Lock& lock);
   int number_of_moves() const;

diff --git a/src/search.cpp b/src/search.cpp
index d93493c29d40757b0341f8523b23b8a68d4a450b..0c5ead46754c20411fe6ab3de99953dceb884524 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1281,21 +1281,57 @@ namespace {
     bool mateThreat = false;
     bool isCheck = pos.is_check();
 
-    bool useNullMove = (    allowNullmove
-                        &&  depth > OnePly
-                        && !isCheck
-                        && !value_is_mate(beta)
-                        &&  ok_to_do_nullmove(pos)
-                        &&  approximateEval >= beta - NullMoveMargin);
+    // Null move search
+    if (    allowNullmove
+        &&  depth > OnePly
+        && !isCheck
+        && !value_is_mate(beta)
+        &&  ok_to_do_nullmove(pos)
+        &&  approximateEval >= beta - NullMoveMargin)
+    {
+        ss[ply].currentMove = MOVE_NULL;
+
+        StateInfo st;
+        pos.do_null_move(st);
+        int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
+
+        Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
+
+        pos.undo_null_move();
 
+        if (nullValue >= beta)
+        {
+            if (depth < 6 * OnePly)
+                return beta;
+
+            // Do zugzwang verification search
+            Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
+            if (v >= beta)
+                return beta;
+        } else {
+            // The null move failed low, which means that we may be faced with
+            // some kind of threat. If the previous move was reduced, check if
+            // the move that refuted the null move was somehow connected to the
+            // move which was reduced. If a connection is found, return a fail
+            // low score (which will cause the reduced move to fail high in the
+            // parent node, which will trigger a re-search with full depth).
+            if (nullValue == value_mated_in(ply + 2))
+                mateThreat = true;
+
+            ss[ply].threatMove = ss[ply + 1].currentMove;
+            if (   depth < ThreatDepth
+                && ss[ply - 1].reduction
+                && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
+                return beta - 1;
+        }
+    }
     // Null move search not allowed, try razoring
-    if (    !useNullMove
-         && !value_is_mate(beta)
-         && depth < RazorDepth
-         && approximateEval < beta - RazorApprMargins[int(depth) - 2]
-         && ss[ply - 1].currentMove != MOVE_NULL
-         && ttMove == MOVE_NONE
-         && !pos.has_pawn_on_7th(pos.side_to_move()))
+    else if (   !value_is_mate(beta)
+             && depth < RazorDepth
+             && approximateEval < beta - RazorApprMargins[int(depth) - 2]
+             && ss[ply - 1].currentMove != MOVE_NULL
+             && ttMove == MOVE_NONE
+             && !pos.has_pawn_on_7th(pos.side_to_move()))
     {
         Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
         if (v < beta - RazorMargins[int(depth) - 2])
@@ -1312,7 +1348,7 @@ namespace {
 
     // Initialize a MovePicker object for the current position, and prepare
     // to search all moves.
-    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], useNullMove);
+    MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
 
     Move move, movesSearched[256];
     int moveCount = 0;
@@ -1328,48 +1364,6 @@ namespace {
            && (move = mp.get_next_move()) != MOVE_NONE
            && !thread_should_stop(threadID))
     {
-
-      // Null move search
-      if (move == MOVE_NULL)
-      {
-          ss[ply].currentMove = MOVE_NULL;
-
-          StateInfo st;
-          pos.do_null_move(st);
-          int R = (depth >= 5 * OnePly ? 4 : 3); // Null move dynamic reduction
-
-          Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
-
-          pos.undo_null_move();
-
-          if (nullValue >= beta)
-          {
-              if (depth < 6 * OnePly)
-                  return beta;
-
-              // Do zugzwang verification search
-              Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
-              if (v >= beta)
-                  return beta;
-          } else {
-              // The null move failed low, which means that we may be faced with
-              // some kind of threat. If the previous move was reduced, check if
-              // the move that refuted the null move was somehow connected to the
-              // move which was reduced. If a connection is found, return a fail
-              // low score (which will cause the reduced move to fail high in the
-              // parent node, which will trigger a re-search with full depth).
-              if (nullValue == value_mated_in(ply + 2))
-                  mateThreat = true;
-
-              ss[ply].threatMove = ss[ply + 1].currentMove;
-              if (   depth < ThreatDepth
-                  && ss[ply - 1].reduction
-                  && connected_moves(pos, ss[ply - 1].currentMove, ss[ply].threatMove))
-                  return beta - 1;
-          }
-          continue;
-      }
-
       assert(move_is_ok(move));
 
       bool singleReply = (isCheck && mp.number_of_moves() == 1);