Remove !extension check official-stockfish#2045

xoto10 · mcostalba · commit d320de761951 · 2019-03-20T14:57:34.000+01:00
While looking at pruning using see_ge() (which is very valuable) it became apparent that the !extension test is not adding any value - simplify it away. STC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 56843 W: 12621 L: 12569 D: 31653 http://tests.stockfishchess.org/tests/view/5c8588cb0ebc5925cffe77f4 LTC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 78622 W: 13223 L: 13195 D: 52204 http://tests.stockfishchess.org/tests/view/5c8611cc0ebc5925cffe7f86 Further work could be to optimize the remaining see_ge() test. The idea of less pruning at higher depths is valuable, but perhaps the test (-PawnValueEg * depth) can be improved. Bench: 3188688
diff --git a/src/search.cpp b/src/search.cpp
@@ -970,8 +970,7 @@ namespace {
               if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
                   continue;
           }
-          else if (   !extension // (~20 Elo)
-                   && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY)))
+          else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
                   continue;
       }
 

Original file line number	Diff line number	Diff line change
`@@ -970,8 +970,7 @@ namespace {`
`970`	`970`	`if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))`
`971`	`971`	`continue;`
`972`	`972`	`}`
`973`		`- else if ( !extension // (~20 Elo)`
`974`		`- && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY)))`
	`973`	`+ else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)`
`975`	`974`	`continue;`
`976`	`975`	`}`
`977`	`976`