Refactor king ring calculation

Rocky640 · snicolet · commit 64a6138d3736 · 2018-12-16T09:57:43.000+01:00
Compute the "double protection by pawns" expression only once in initialize(), instead of once for each piece in the piece loop. Passed STC http://tests.stockfishchess.org/tests/view/5c1506380ebc5902ba11f3b4 LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 9494 W: 2191 L: 2045 D: 5258 Inspired by Nick Pelling's test http://tests.stockfishchess.org/tests/view/5c144d110ebc5902ba11e4af and an older test of mine http://tests.stockfishchess.org/tests/view/5c0402810ebc5902bcee1fc8 Non functional change.
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -274,6 +274,7 @@ namespace {
             kingRing[Us] |= shift<EAST>(kingRing[Us]);
 
         kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
+        kingRing[Us] &= ~double_pawn_attacks_bb<Us>(pos.pieces(Us, PAWN));
         kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
     }
   }
@@ -309,7 +310,7 @@ namespace {
         attackedBy[Us][Pt] |= b;
         attackedBy[Us][ALL_PIECES] |= b;
 
-        if (b & kingRing[Them] & ~double_pawn_attacks_bb<Them>(pos.pieces(Them, PAWN)))
+        if (b & kingRing[Them])
         {
             kingAttackersCount[Us]++;
             kingAttackersWeight[Us] += KingAttackWeights[Pt];

Original file line number	Diff line number	Diff line change
`@@ -274,6 +274,7 @@ namespace {`
`274`	`274`	`kingRing[Us] \|= shift<EAST>(kingRing[Us]);`
`275`	`275`
`276`	`276`	`kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));`
	`277`	`+ kingRing[Us] &= ~double_pawn_attacks_bb<Us>(pos.pieces(Us, PAWN));`
`277`	`278`	`kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;`
`278`	`279`	`}`
`279`	`280`	`}`
`@@ -309,7 +310,7 @@ namespace {`
`309`	`310`	`attackedBy[Us][Pt] \|= b;`
`310`	`311`	`attackedBy[Us][ALL_PIECES] \|= b;`
`311`	`312`
`312`		`- if (b & kingRing[Them] & ~double_pawn_attacks_bb<Them>(pos.pieces(Them, PAWN)))`
	`313`	`+ if (b & kingRing[Them])`
`313`	`314`	`{`
`314`	`315`	`kingAttackersCount[Us]++;`
`315`	`316`	`kingAttackersWeight[Us] += KingAttackWeights[Pt];`