1 files changed, 25 insertions, 5 deletions

diff --git a/src/eval.c b/src/eval.c
index b6a7792..48a21e0 100755
--- a/src/eval.c
+++ b/src/eval.c
@@ -5596,7 +5596,7 @@ Return value:
     //
     // Check the eval hash
     // 
-    iScoreForSideToMove = ProbeEvalHash(ctx);
+    iScoreForSideToMove = ProbeEvalHash(ctx, iAlpha, iBeta);
     if (iScoreForSideToMove != INVALID_SCORE) 
     {
         INC(ctx->sCounters.tree.u64EvalHashHits);
@@ -5714,12 +5714,32 @@ Return value:
         // 
         _QuicklyEstimateKingSafetyTerm(pos, &iAlphaMargin, &iBetaMargin);
         _QuicklyEstimatePasserBonuses(pos, pHash, &iAlphaMargin, &iBetaMargin);
-        
-        if ((iScoreForSideToMove + iAlphaMargin <= iAlpha) ||
-            (iScoreForSideToMove - iBetaMargin >= iBeta))
+
+        if (iScoreForSideToMove + iAlphaMargin <= iAlpha)
         {
             ctx->uPositional = MINU(200, ctx->uPositional);
             INC(ctx->sCounters.tree.u64LazyEvals);
+#ifdef EVAL_HASH
+            //
+            // The true eval can't reach iAlpha; that's a fact about
+            // the position (not this particular window), so remember
+            // it as a proven upper bound for reuse by later probes.
+            //
+            StoreEvalHash(ctx, iScoreForSideToMove,
+                         (SCORE)(iScoreForSideToMove + iAlphaMargin),
+                         EVAL_HASH_UPPER);
+#endif
+            goto end;
+        }
+        else if (iScoreForSideToMove - iBetaMargin >= iBeta)
+        {
+            ctx->uPositional = MINU(200, ctx->uPositional);
+            INC(ctx->sCounters.tree.u64LazyEvals);
+#ifdef EVAL_HASH
+            StoreEvalHash(ctx, iScoreForSideToMove,
+                         (SCORE)(iScoreForSideToMove - iBetaMargin),
+                         EVAL_HASH_LOWER);
+#endif
             goto end;
         }
     }
@@ -6102,7 +6122,7 @@ Return value:
     //
     // Store in eval hash.
     //
-    StoreEvalHash(ctx, iScoreForSideToMove);
+    StoreEvalHash(ctx, iScoreForSideToMove, 0, EVAL_HASH_EXACT);
 #endif
 
  end: