Update pawn history based on static eval difference

Vizvezdenec · vondele · commit b4b704e6866b · 2023-11-03T22:50:05.000+01:00
Use the same logic as in main history but with 1/4 multiplier. Passed STC: https://tests.stockfishchess.org/tests/view/653c1282cc309ae8395615bf LLR: 2.93 (-2.94,2.94) <0.00,2.00> Total: 306624 W: 77811 L: 77094 D: 151719 Ptnml(0-2): 975, 36411, 77830, 37114, 982 Passed LTC: https://tests.stockfishchess.org/tests/view/654258e2cc309ae83956818d LLR: 2.94 (-2.94,2.94) <0.50,2.50> Total: 99150 W: 24681 L: 24228 D: 50241 Ptnml(0-2): 56, 11107, 26792, 11568, 52 closes #4859 bench 1330590
diff --git a/src/search.cpp b/src/search.cpp
@@ -745,6 +745,8 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
     {
         int bonus = std::clamp(-18 * int((ss - 1)->staticEval + ss->staticEval), -1812, 1812);
         thisThread->mainHistory[~us][from_to((ss - 1)->currentMove)] << bonus;
+        if (type_of(pos.piece_on(prevSq)) != PAWN && type_of((ss - 1)->currentMove) != PROMOTION)
+            thisThread->pawnHistory[pawn_structure(pos)][pos.piece_on(prevSq)][prevSq] << bonus / 4;
     }
 
     // Set up the improving flag, which is true if current static evaluation is

Original file line number	Diff line number	Diff line change
`@@ -745,6 +745,8 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo`
`745`	`745`	`{`
`746`	`746`	`int bonus = std::clamp(-18 * int((ss - 1)->staticEval + ss->staticEval), -1812, 1812);`
`747`	`747`	`thisThread->mainHistory[~us][from_to((ss - 1)->currentMove)] << bonus;`
	`748`	`+ if (type_of(pos.piece_on(prevSq)) != PAWN && type_of((ss - 1)->currentMove) != PROMOTION)`
	`749`	`+ thisThread->pawnHistory[pawn_structure(pos)][pos.piece_on(prevSq)][prevSq] << bonus / 4;`
`748`	`750`	`}`
`749`	`751`
`750`	`752`	`// Set up the improving flag, which is true if current static evaluation is`