Updated to "Simplification for countermoves based pruning".

official-stockfish/Stockfish@61e1c66
syzygy1 · Jun 26, 2021 · fb847b0 · fb847b0
1 parent 68d5df3
commit fb847b0
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Showing 2 changed files with 16 additions and 30 deletions.
diff --git a/src/Makefile b/src/Makefile
@@ -381,6 +381,16 @@ ifeq ($(ARCH),ppc-64)
 	prefetch = yes
 endif
 
+ifneq ($(findstring e2k,$(ARCH)),)
+	arch = e2k
+	bits = 64
+	sse = yes
+	sse2 = yes
+	ssse3 = yes
+	sse41 = yes
+	popcnt = yes
+endif
+
 endif
 
 ifeq ($(avx2),yes)
@@ -820,6 +830,7 @@ help:
 	@echo "armv7-neon              > ARMv7 32-bit with popcnt and neon"
 	@echo "armv7                   > ARMv7 32-bit"
 	@echo "apple-silicon           > Apple silicon ARM64"
+	@echo "e2k                     > Elbrus 2000"
 	@echo "general-64              > unspecified 64-bit"
 	@echo "general-32              > unspecified 32-bit"
 	@echo ""
@@ -948,7 +959,8 @@ config-sanity: net
 	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
 	@test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
 	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || \
-	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64"
+	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64" || \
+	 test "$(arch)" = "e2k"
 	@test "$(bits)" = "32" || test "$(bits)" = "64"
 	@test "$(prefetch)" = "yes" || test "$(prefetch)" = "no"
 	@test "$(popcnt)" = "yes" || test "$(popcnt)" = "no"

diff --git a/src/search.c b/src/search.c
@@ -971,14 +971,6 @@ INLINE Value search_node(Position *pos, Stack *ss, Value alpha, Value beta,
            && ttValue != VALUE_NONE
            && ttValue < probCutBeta))
   {
-    if (   ss->ttHit
-        && tte_depth(tte) >= depth - 3
-        && ttValue != VALUE_NONE
-        && ttValue >= probCutBeta
-        && ttMove
-        && is_capture_or_promotion(pos, ttMove))
-      return probCutBeta;
-
     mp_init_pc(pos, ttMove, probCutBeta - ss->staticEval);
     int probCutCount = 2 + 2 * cutNode;
     bool ttPv = ss->ttPv;
@@ -1136,7 +1128,7 @@ INLINE Value search_node(Position *pos, Stack *ss, Value alpha, Value beta,
       } else {
 
         // Countermoves based pruning
-        if (   lmrDepth < 4 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
+        if (   lmrDepth < 4
             && (*cmh )[movedPiece][to_sq(move)] < CounterMovePruneThreshold
             && (*fmh )[movedPiece][to_sq(move)] < CounterMovePruneThreshold)
           continue;
@@ -1278,14 +1270,7 @@ INLINE Value search_node(Position *pos, Stack *ss, Value alpha, Value beta,
       if (singularQuietLMR)
         r--;
 
-      if (captureOrPromotion) {
-        // Unless giving check, this capture is likely bad
-        if (   !givesCheck
-            && ss->staticEval + PieceValue[EG][captured_piece()] + 210 * depth <= alpha)
-          r++;
-
-      } else {
-
+      if (!captureOrPromotion) {
         // Increase reduction if ttMove is a capture
         if (ttCapture)
           r++;
@@ -1304,18 +1289,7 @@ INLINE Value search_node(Position *pos, Stack *ss, Value alpha, Value beta,
                        + (*pos->mainHistory)[!stm()][from_to(move)]
                        - 4741;
 
-        // Decrease/increase reduction by comparing with opponent's stat score.
-        if (ss->statScore >= -89 && (ss-1)->statScore < -116)
-          r--;
-
-        else if ((ss-1)->statScore >= -112 && ss->statScore < -100)
-          r++;
-
-        // Decrease/increase reduction for moves with a good/bad history.
-        if (inCheck)
-          r -= (  (*pos->mainHistory)[!stm()][from_to(move)]
-                + (*cmh)[movedPiece][to_sq(move)] - 3833) / 16384;
-        else
+        if (!inCheck)
           r -= ss->statScore / 14790;
       }