From 09b6d28391cf582d99897360b225bcbbe38dd1c6 Mon Sep 17 00:00:00 2001
From: Vizvezdenec <Vizvezdenec@gmail.com>
Date: Tue, 6 Jul 2021 20:44:50 +0300
Subject: [PATCH] Remove futility pruning depth limit

This patch removes futility pruning depth limit for child node futility pruning.
In current master it was double capped by depth and by futility margin, which is also a function of depth, which didn't make much sense.

passed STC
https://tests.stockfishchess.org/tests/view/60e2418f9ea99d7c2d693e64
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 116168 W: 9100 L: 9097 D: 97971
Ptnml(0-2): 319, 7496, 42476, 7449, 344

passed LTC
https://tests.stockfishchess.org/tests/view/60e3374f9ea99d7c2d693f20
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 43304 W: 1282 L: 1231 D: 40791
Ptnml(0-2): 8, 1126, 19335, 1173, 10

closes https://github.com/official-stockfish/Stockfish/pull/3606

bench 4965493
---
 src/search.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index 5974cba7..008a60ed 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -780,7 +780,6 @@ namespace {
 
     // Step 7. Futility pruning: child node (~50 Elo)
     if (   !PvNode
-        &&  depth < 9
         &&  eval - futility_margin(depth, improving) >= beta
         &&  eval < VALUE_KNOWN_WIN) // Do not return unproven wins
         return eval;
-- 
2.39.2