Use int8_t instead of int for SquareDistance[]

This patch saves (4-1) * 64 * 64 = 12KiB of cache. STC LLR: 2.95 (-2.94,2.94) [0.00,4.00] Total: 176120 W: 38944 L: 38087 D: 99089 http://tests.stockfishchess.org/tests/view/5c4c9f840ebc593af5d4a7ce LTC As a pure speed up, I've been informed it should not require LTC. No functional change
official-stockfish · Jan 29, 2019 · 8df1cd1 · 8df1cd1
1 parent 2d0af36
commit 8df1cd1
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diff --git a/src/bitboard.cpp b/src/bitboard.cpp
@@ -24,7 +24,7 @@
 #include "misc.h"
 
 uint8_t PopCnt16[1 << 16];
-int SquareDistance[SQUARE_NB][SQUARE_NB];
+int8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
 Bitboard SquareBB[SQUARE_NB];
 Bitboard FileBB[FILE_NB];

diff --git a/src/bitboard.h b/src/bitboard.h
@@ -60,7 +60,7 @@ constexpr Bitboard Rank6BB = Rank1BB << (8 * 5);
 constexpr Bitboard Rank7BB = Rank1BB << (8 * 6);
 constexpr Bitboard Rank8BB = Rank1BB << (8 * 7);
 
-extern int SquareDistance[SQUARE_NB][SQUARE_NB];
+extern int8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
 extern Bitboard SquareBB[SQUARE_NB];
 extern Bitboard FileBB[FILE_NB];