Clean up some pruning in the move loop around MATED scores

This is really a bugfix, as it is possible (although rare) to return a false MATED score when the first move searched is a MATED move, we would trigger a research since this only happens in non PV nodes. Thus, I do not feel the need to test this at LTC. SPRT @ 5.0+0.05s Threads=1 Hash=2MB LLR: 3.00 (-2.94, 2.94) [0.00, 5.00] Games: 25675 W: 6956 L: 6670 D: 12049 BENCH : 9,484,343
AndyGrant · Mar 19, 2018 · 4095f4c · 4095f4c
1 parent 479a08b
commit 4095f4c
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Showing 3 changed files with 8 additions and 5 deletions.
diff --git a/src/search.c b/src/search.c
@@ -536,7 +536,7 @@ int search(Thread* thread, PVariation* pv, int alpha, int beta, int depth, int h
         // and we don't expect anything from this move, skip it.
         if (   !PvNode
             &&  isQuiet
-            &&  played >= 1
+            &&  best > MATED_IN_MAX
             &&  futilityMargin <= alpha
             &&  depth <= FutilityPruningDepth)
             break;
@@ -547,7 +547,7 @@ int search(Thread* thread, PVariation* pv, int alpha, int beta, int depth, int h
         if (    !PvNode
             &&  !isQuiet
             &&  !inCheck
-            &&   played >= 1
+            &&   best > MATED_IN_MAX
             &&   captureIsWeak(board, &ei, currentMove, depth))
             continue;
 
@@ -564,7 +564,7 @@ int search(Thread* thread, PVariation* pv, int alpha, int beta, int depth, int h
         if (   !PvNode
             && !board->kingAttackers
             &&  isQuiet
-            &&  played >= 1
+            &&  best > MATED_IN_MAX
             &&  depth <= LateMovePruningDepth
             &&  quiets > LateMovePruningCounts[depth]){
 

diff --git a/src/types.h b/src/types.h
@@ -26,11 +26,14 @@
 #define MIN(A, B) ((A) < (B) ? (A) : (B))
 #define MAX(A, B) ((A) > (B) ? (A) : (B))
 
-#define MATE       (16000)
 #define MAX_DEPTH  (128)
 #define MAX_HEIGHT (256)
 #define MAX_MOVES  (256)
 
+#define MATE         (16000)
+#define MATE_IN_MAX  (+MATE - MAX_HEIGHT)
+#define MATED_IN_MAX (-MATE + MAX_HEIGHT)
+
 #define SQUARE_NB (64)
 #define COLOUR_NB ( 2)
 #define RANK_NB   ( 8)

diff --git a/src/uci.c b/src/uci.c
@@ -82,7 +82,7 @@ int main(){
         getInput(str);
 
         if (stringEquals(str, "uci")){
-            printf("id name Ethereal 9.29\n");
+            printf("id name Ethereal 9.30\n");
             printf("id author Andrew Grant\n");
             printf("option name Hash type spin default 16 min 1 max 65536\n");
             printf("option name Threads type spin default 1 min 1 max 2048\n");