Simplify away tactical late move reductions

Bench: 5343783

STC
ELO   | 0.89 +- 2.40 (95%)
SPRT  | 10.0+0.10s Threads=1 Hash=8MB
LLR   | 2.99 (-2.94, 2.94) [-3.00, 1.00]
GAMES | N: 36736 W: 8476 L: 8382 D: 19878

LTC
ELO   | -0.91 +- 1.86 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | -0.68 (-2.94, 2.94) [-3.00, 1.00]
GAMES | N: 58256 W: 12595 L: 12747 D: 32914

Author: jhonnold

src/search.c

@@ -561,38 +561,33 @@ int Negamax(int alpha, int beta, int depth, int cutnode, ThreadData* thread, PV*
 
     // Late move reductions
     int R = 1;
-    if (depth > 2 && playedMoves > 1) {
+    if (depth > 2 && playedMoves > 1 && !tactical) {
       R = LMR[min(depth, 63)][min(playedMoves, 63)];
 
-      if (!tactical) {
-        // increase reduction on non-pv
-        if (!isPV) R++;
+      // increase reduction on non-pv
+      if (!isPV) R++;
 
-        // increase reduction if our eval is declining
-        if (!improving) R++;
+      // increase reduction if our eval is declining
+      if (!improving) R++;
 
-        // reduce these special quiets less
-        if (killerOrCounter) R -= 2;
+      // reduce these special quiets less
+      if (killerOrCounter) R -= 2;
 
-        // less likely a non-capture is best
-        if (IsCap(hashMove)) R++;
+      // less likely a non-capture is best
+      if (IsCap(hashMove)) R++;
 
-        // move GAVE check
-        if (board->checkers) R--;
-
-        // adjust reduction based on historical score
-        R -= history / 20480;
-      } else {
-        int th = GetTacticalHistory(data, board, move);
-        R = 1 - 4 * th / (abs(th) + 24576);
-      }
+      // move GAVE check
+      if (board->checkers) R--;
 
       // Reduce more on expected cut nodes
       // idea from komodo/sf, explained by Don Daily here
       // https://talkchess.com/forum3/viewtopic.php?f=7&t=47577&start=10#p519741
       // and https://www.chessprogramming.org/Node_Types
       if (cutnode) R++;
 
+      // adjust reduction based on historical score
+      R -= history / 20480;
+
       // prevent dropping into QS, extending, or reducing all extensions
       R = min(depth - 1, max(R, 1));
     }