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Change definition of between_bb()

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We remark that in current master, most of our use cases for between_bb() can be
optimized if the second parameter of the function is added to the segment. So we
change the definition of between_bb(s1, s2) such that it excludes s1 but includes s2.

We also use a precomputed array for between_bb() for another small speed gain
(see https://tests.stockfishchess.org/tests/view/604d09f72433018de7a389fb).

Passed STC:
LLR: 2.96 (-2.94,2.94) {-0.25,1.25}
Total: 18736 W: 1746 L: 1607 D: 15383
Ptnml(0-2): 61, 1226, 6644, 1387, 50
https://tests.stockfishchess.org/tests/view/60428c84ddcba5f0627bb6e4

Yellow LTC:
LTC:
LLR: -3.00 (-2.94,2.94) {0.25,1.25}
Total: 39144 W: 1431 L: 1413 D: 36300
Ptnml(0-2): 13, 1176, 17184, 1178, 21
https://tests.stockfishchess.org/tests/view/605128702433018de7a38ca1

Closes https://github.com/official-stockfish/Stockfish/pull/3397

---------

Verified for correctness by running perft on the following position:

./stockfish
position fen 4rrk1/1p1nq3/p7/2p1P1pp/3P2bp/3Q1Bn1/PPPB4/1K2R1NR w - - 40 21
go perft 6

Nodes searched: 6136386434

--------

No functional change
This commit is contained in:
bmc4
2021-03-15 16:06:42 -03:00
committed by Stéphane Nicolet
parent d58e83695f
commit 5089061659
4 changed files with 27 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
src/movegen.cpp
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@@ -158,7 +158,7 @@ namespace {
{
assert(rank_of(pos.ep_square()) == relative_rank(Us, RANK_6));
// An en passant capture cannot resolve a discovered check.
// An en passant capture cannot resolve a discovered check
if (Type == EVASIONS && (target & (pos.ep_square() + Up)))
return moveList;
@@ -218,7 +218,7 @@ namespace {
target = ~pos.pieces();
break;
case EVASIONS:
target = between_bb(pos.square<KING>(Us), lsb(pos.checkers())) | pos.checkers();
target = between_bb(pos.square<KING>(Us), lsb(pos.checkers()));
break;
case NON_EVASIONS:
target = ~pos.pieces(Us);
@@ -329,7 +329,7 @@ ExtMove* generate<EVASIONS>(const Position& pos, ExtMove* moveList) {
if (more_than_one(pos.checkers()))
return moveList; // Double check, only a king move can save the day
// Generate blocking evasions or captures of the checking piece
// Generate blocking interpositions or captures of the checking piece
return us == WHITE ? generate_all<WHITE, EVASIONS>(pos, moveList)
: generate_all<BLACK, EVASIONS>(pos, moveList);
}