Introduce countermove based pruning for qsearch
authorVizvezdenec <Vizvezdenec@gmail.com>
Mon, 24 Aug 2020 05:04:16 +0000 (08:04 +0300)
committerJoost VandeVondele <Joost.VandeVondele@gmail.com>
Mon, 24 Aug 2020 10:09:04 +0000 (12:09 +0200)
commit843a961a8c10d5949e04718b829e3b3d5adeedb4
tree67ac1d98bd99be11578c111a8ef1fd6aaaa0d669
parentf7b3f0e8426bbf7414d139ed9d1cfa7a98d7314d
Introduce countermove based pruning for qsearch

This patch continues work of previous patch in introducing pruning heuristics in qsearch by analogy to main search, now with countermove based pruning.
Idea is that if move is late enough and is quite check (we do generate them in qsearch) and has bad enough countermove history - prune it.

passed STC
https://tests.stockfishchess.org/tests/view/5f41220287a5c3c63d8f53c5
LLR: 2.93 (-2.94,2.94) {-0.25,1.25}
Total: 35944 W: 4127 L: 3929 D: 27888
Ptnml(0-2): 196, 2970, 11459, 3134, 213

passed LTC
https://tests.stockfishchess.org/tests/view/5f41862f87a5c3c63d8f53e8
LLR: 2.95 (-2.94,2.94) {0.25,1.25}
Total: 138448 W: 7655 L: 7252 D: 123541
Ptnml(0-2): 145, 6247, 56043, 6638, 151

closes https://github.com/official-stockfish/Stockfish/pull/3058

Bench: 3610676
src/search.cpp