Simplify extra continuation history updates

daniel-monroe · vondele · commit 525a5749bc87 · 2025-07-28T20:13:15.000+02:00
Passed simplification STC LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 254464 W: 65774 L: 65793 D: 122897 Ptnml(0-2): 699, 30087, 65638, 30150, 658 https://tests.stockfishchess.org/tests/view/68863283966ed85face24a59 Passed simplification LTC LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 144750 W: 37111 L: 37018 D: 70621 Ptnml(0-2): 79, 15676, 40764, 15785, 71 https://tests.stockfishchess.org/tests/view/6886655f7b562f5f7b731359 closes #6189 Bench: 3071078
diff --git a/src/search.cpp b/src/search.cpp
@@ -1856,16 +1856,13 @@ void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
     static constexpr std::array<ConthistBonus, 6> conthist_bonuses = {
       {{1, 1108}, {2, 652}, {3, 273}, {4, 572}, {5, 126}, {6, 449}}};
 
-    static constexpr int conthist_offsets[6]{71, 106, -22, -20, 29, -74};
-
     for (const auto [i, weight] : conthist_bonuses)
     {
         // Only update the first 2 continuation histories if we are in check
         if (ss->inCheck && i > 2)
             break;
         if (((ss - i)->currentMove).is_ok())
-            (*(ss - i)->continuationHistory)[pc][to]
-              << (bonus * weight / 1024) + conthist_offsets[i - 1];
+            (*(ss - i)->continuationHistory)[pc][to] << (bonus * weight / 1024) + 80 * (i < 2);
     }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -1856,16 +1856,13 @@ void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {`
`1856`	`1856`	`static constexpr std::array<ConthistBonus, 6> conthist_bonuses = {`
`1857`	`1857`	`{{1, 1108}, {2, 652}, {3, 273}, {4, 572}, {5, 126}, {6, 449}}};`
`1858`	`1858`
`1859`		`- static constexpr int conthist_offsets[6]{71, 106, -22, -20, 29, -74};`
`1860`		`-`
`1861`	`1859`	`for (const auto [i, weight] : conthist_bonuses)`
`1862`	`1860`	`{`
`1863`	`1861`	`// Only update the first 2 continuation histories if we are in check`
`1864`	`1862`	`if (ss->inCheck && i > 2)`
`1865`	`1863`	`break;`
`1866`	`1864`	`if (((ss - i)->currentMove).is_ok())`
`1867`		`- (*(ss - i)->continuationHistory)[pc][to]`
`1868`		`- << (bonus * weight / 1024) + conthist_offsets[i - 1];`
	`1865`	`+ ((ss - i)->continuationHistory)[pc][to] << (bonus weight / 1024) + 80 * (i < 2);`
`1869`	`1866`	`}`
`1870`	`1867`	`}`
`1871`	`1868`