Plumb iImprovement into LMR and futiltiy and parallel search.

Fix a bug (iEval) in HelpSearch
This commit changes the heuristics for: nullmove pruning, LMR, and EFP slightly.

1 files changed, 39 insertions, 36 deletions

diff --git a/src/searchsup.c b/src/searchsup.c
index d2cbbbd..9ad4303 100644
--- a/src/searchsup.c
+++ b/src/searchsup.c
@@ -188,15 +188,16 @@ ThreadUnderTerminatingSplit(IN SEARCHER_THREAD_CONTEXT *ctx)
 
 
 INT
-GetLMRReduction(IN SCORE iRoughEval,
-               IN SCORE iAlpha,
-               IN SCORE iBeta,
-               IN SEARCHER_THREAD_CONTEXT *ctx,
-               IN ULONG uRemainingDepth,
-               IN ULONG uLegalMoves,
-               IN MOVE mv,
-               IN ULONG uMoveNum,
-               IN INT iExtend)
+GetLMRReduction(IN SCORE iEval,
+                IN SCORE iAlpha,
+                IN SCORE iBeta,
+                IN SCORE iImprovement,
+                IN SEARCHER_THREAD_CONTEXT *ctx,
+                IN ULONG uRemainingDepth,
+                IN ULONG uLegalMoves,
+                IN MOVE mv,
+                IN ULONG uMoveNum,
+                IN INT iExtend)
 /**
 
 Routine description:
@@ -206,6 +207,8 @@ Routine description:
     counter-move exemption. Kept under the GetLMRReduction name so
     search.c/split.c's call sites need no changes.
 
+    Note: the move has already been made by the time we get here.
+
 Return value:
 
     INT : 0 if no reduction, else -ONE_PLY.
@@ -215,6 +218,7 @@ Return value:
     ASSERT(ctx->uPly > 0);
     ASSERT(mv.uMove);
     ASSERT((uMoveNum > 0) || (uLegalMoves == 0));
+
     if ((uRemainingDepth >= TWO_PLY) &&
         (FALSE == ctx->sPlyInfo[ctx->uPly - 1].fPvNode) &&
         (uLegalMoves > 5) &&
@@ -230,6 +234,9 @@ Return value:
         (GetMoveFailHighPercentage(mv, NULL) <= 10))
     {
         ASSERT(!InCheck(&ctx->sPosition, ctx->sPosition.uToMove));
+        if (iImprovement <= 40) {
+            return(-(ONE_PLY + QUARTER_PLY));
+        }
         return(-ONE_PLY);
     }
     return(0);
@@ -369,15 +376,14 @@ Return value:
 }
 
 
-void
-ComputeMoveExtension(IN SEARCHER_THREAD_CONTEXT *ctx,
-                     IN SCORE iAlpha,
-                     IN SCORE iBeta,
-                     IN ULONG uMoveNum,
-                     IN SCORE iRoughEval,
-                     IN ULONG uDepth,
-                     IN SCORE iCheckSee,
-                     IN OUT INT *piExtend)
+void ComputeMoveExtension(IN SEARCHER_THREAD_CONTEXT *ctx,
+                          IN SCORE iAlpha,
+                          IN SCORE iBeta,
+                          IN ULONG uMoveNum,
+                          IN SCORE iRoughEval,
+                          IN ULONG uDepth,
+                          IN SCORE iCheckSee,
+                          IN OUT INT *piExtend)
 /**
 
 Routine description:
@@ -482,13 +488,13 @@ Return value:
     {
         ASSERT(IS_ESCAPING_CHECK(mv));
         iMoveScore = iRoughEval + ComputeMoveScore(ctx, mv, uMoveNum);
-        
+
         // One legal move in reply to check...
         if (ONE_LEGAL_MOVE(ctx, ctx->uPly - 1) &&
-            CountKingSafetyDefects(&ctx->sPosition, uColor) > 1) 
+            CountKingSafetyDefects(&ctx->sPosition, uColor) > 1)
         {
             *piExtend += (QUARTER_PLY +
-                          HALF_PLY * 
+                          HALF_PLY *
                           (iMoveScore + VALUE_KNIGHT > iAlpha));
             INC(ctx->sCounters.extension.uOneLegalMove);
         }
@@ -511,7 +517,7 @@ Return value:
     {
         // Endgame extension
         if ((ctx->sPlyInfo[1].uTotalNonPawns > 2) &&
-            ((pos->uNonPawnCount[BLACK][0] + 
+            ((pos->uNonPawnCount[BLACK][0] +
               pos->uNonPawnCount[WHITE][0]) == 2))
         {
             if ((mv.pCaptured && !IS_PAWN(mv.pCaptured)) ||
@@ -529,7 +535,7 @@ Return value:
             if (uDepth <= THREE_PLY)
             {
                 if ((mv.pCaptured) && !IS_PAWN(mv.pCaptured) &&
-                    ((PIECE_VALUE(mv.pCaptured) == 
+                    ((PIECE_VALUE(mv.pCaptured) ==
                       PIECE_VALUE(mvLast.pCaptured)) ||
                      ((mvLast.pPromoted) && (mv.cTo == mvLast.cTo))))
                 {
@@ -1092,11 +1098,11 @@ SelectNullmoveRFactor(SEARCHER_THREAD_CONTEXT *ctx,
 FLAG WeShouldTryNullmovePruning(SEARCHER_THREAD_CONTEXT *ctx,
                                 SCORE iAlpha,
                                 SCORE iBeta,
-                                SCORE iRoughEval,
-	                            SCORE iImprovement,
-                                ULONG uNullDepth)
+                                SCORE iEval,
+                                SCORE iImprovement,
+	                            ULONG uNullDepth)
 {
-    static SCORE iSkipNullMargins[] = {
+    static SCORE iSkipShallowNullIfThisFarBelowAlpha[] = {
       700, 950, 1110, 1150, 1190, 1230, 1270, 0
     };
     POSITION *pos = &ctx->sPosition;
@@ -1113,20 +1119,17 @@ FLAG WeShouldTryNullmovePruning(SEARCHER_THREAD_CONTEXT *ctx,
         (pos->uNonPawnCount[pos->uToMove][0] > 2) &&
         (FALSE == pi->fInCheck) &&
         (iBeta != +INFINITY) &&
-        (FALSE == pi->fPvNode)) // <--- TODO: test this one please...
+        (FALSE == pi->fPvNode))
     {
         if (uNullDepth <= 6 * ONE_PLY)
         {
             u = uNullDepth / ONE_PLY;
             ASSERT(u <= 6);
-            SCORE iMargin = iSkipNullMargins[u];
-            if (iImprovement > 0)
-			{
-                iMargin -= iImprovement;
-				iMargin = MAX(0, iMargin);
-			}
-            if ((iRoughEval + iMargin <= iAlpha) ||
-                ((iRoughEval + iMargin / 2 <= iAlpha) &&
+            SCORE iMargin = iSkipShallowNullIfThisFarBelowAlpha[u];
+            iMargin -= iImprovement;    // Note: if improving, makes null more likely
+            iMargin = MAX(0, iMargin);  //       if not, less likely.
+            if ((iEval + iMargin <= iAlpha) ||
+                ((iEval + iMargin / 2 <= iAlpha) &&
                  (ValueOfMaterialInTroubleAfterNull(ctx, pos->uToMove))))
             {
                 return FALSE;