Small reformat in evaluate threats (non functional)

When evaluating threat by safe pawn and pawn push the same expression is used.

STC
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 19444 W: 4540 L: 4309 D: 10595
http://tests.stockfishchess.org/tests/view/5b5a6e150ebc5902bdb8c5c0

Closes https://github.com/official-stockfish/Stockfish/pull/1709

No functional change.

--------------------

Comments by Stéphane Nicolet:

I don't measure any speed-up on my system, with two parallel benches at depth 22:

Total time (ms) : 74989
Nodes searched : 144830258
Nodes/second : 1931353
master

Total time (ms) : 75341
Nodes searched : 144830258
Nodes/second : 1922329
testedpatch

And anyway, like Stefan Geschwentner, I don't think that a 0.3% speed-up would
be enough to pass a [0..5] LTC test -- as a first approximation, we have this
rule of thumb that 1% speed-up gives about 1 Elo point.

However, considering the facts that the reformatting by itself is interesting,
that this is your first green test and that you played by the rules by running
the SPRT[0..5] test before opening the pull request, I will commit the change.
I will only take the liberty to change the occurrences of safe in lines 590 and
591 to b, to make the code more similar to lines 584 and 585.

So approved, and congrats :-)

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index bbab9c5032e09aaba7cba6f7c544721b76253db9..31419146667d95918d2a14ff311c2214763fb29f 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -513,7 +513,7 @@ namespace {
     constexpr Direction Up       = (Us == WHITE ? NORTH   : SOUTH);
     constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
 
-    Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safeThreats;
+    Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safe;
     Score score = SCORE_ZERO;
 
     // Non-pawn enemies
@@ -530,6 +530,9 @@ namespace {
     // Enemies not strongly protected and under our attack
     weak = pos.pieces(Them) & ~stronglyProtected & attackedBy[Us][ALL_PIECES];
 
+    // Safe or protected squares
+    safe = ~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES];
+
     // Bonus according to the kind of attacking pieces
     if (defended | weak)
     {
@@ -570,39 +573,37 @@ namespace {
     if (pos.pieces(Us, ROOK, QUEEN))
         score += WeakUnopposedPawn * pe->weak_unopposed(Them);
 
-    // Our safe or protected pawns
-    b =   pos.pieces(Us, PAWN)
-       & (~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES]);
-
-    safeThreats = pawn_attacks_bb<Us>(b) & nonPawnEnemies;
-    score += ThreatBySafePawn * popcount(safeThreats);
-
     // Find squares where our pawns can push on the next move
     b  = shift<Up>(pos.pieces(Us, PAWN)) & ~pos.pieces();
     b |= shift<Up>(b & TRank3BB) & ~pos.pieces();
 
     // Keep only the squares which are relatively safe
-    b &= ~attackedBy[Them][PAWN]
-        & (attackedBy[Us][ALL_PIECES] | ~attackedBy[Them][ALL_PIECES]);
+    b &= ~attackedBy[Them][PAWN] & safe;
 
     // Bonus for safe pawn threats on the next move
     b = pawn_attacks_bb<Us>(b) & pos.pieces(Them);
     score += ThreatByPawnPush * popcount(b);
 
+    // Our safe or protected pawns
+    b = pos.pieces(Us, PAWN) & safe;
+
+    b = pawn_attacks_bb<Us>(b) & nonPawnEnemies;
+    score += ThreatBySafePawn * popcount(b);
+
     // Bonus for threats on the next moves against enemy queen
     if (pos.count<QUEEN>(Them) == 1)
     {
         Square s = pos.square<QUEEN>(Them);
-        safeThreats = mobilityArea[Us] & ~stronglyProtected;
+        safe = mobilityArea[Us] & ~stronglyProtected;
 
         b = attackedBy[Us][KNIGHT] & pos.attacks_from<KNIGHT>(s);
 
-        score += KnightOnQueen * popcount(b & safeThreats);
+        score += KnightOnQueen * popcount(b & safe);
 
         b =  (attackedBy[Us][BISHOP] & pos.attacks_from<BISHOP>(s))
            | (attackedBy[Us][ROOK  ] & pos.attacks_from<ROOK  >(s));
 
-        score += SliderOnQueen * popcount(b & safeThreats & attackedBy2[Us]);
+        score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]);
     }
 
     if (T)