From bcddd79056aae804787f84b3ecca87f78b576b7c Mon Sep 17 00:00:00 2001
From: Sam Roelants <sam@samroelants.com>
Date: Thu, 3 Oct 2024 22:44:26 +0200
Subject: [PATCH] SEE prune tacticals

bench 6627328
---
 simbelmyne/src/search/negamax.rs | 20 ++++++++++++--------
 simbelmyne/src/search/params.rs  |  3 +++
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/simbelmyne/src/search/negamax.rs b/simbelmyne/src/search/negamax.rs
index 840924a..c2292b1 100644
--- a/simbelmyne/src/search/negamax.rs
+++ b/simbelmyne/src/search/negamax.rs
@@ -384,17 +384,21 @@ impl<'a> SearchRunner<'a> {
             //
             ////////////////////////////////////////////////////////////////////
 
-            let see_margin = -see_quiet_margin() * depth as Score;
-
             if legal_moves.stage() > Stage::GoodTacticals
-                // FIXME: Make this mv.is_quiet() at some point, but tweak the
-                // pruning margin
-                && mv.get_type() == MoveType::Quiet
+                && (mv.is_tactical() || mv.get_type() == MoveType::Quiet)
                 && move_count > 0
                 && !in_root
-                && !best_score.is_mate()
-                && !pos.board.see(mv, see_margin) {
-                continue;
+                && !best_score.is_mate() {
+
+                let margin = if mv.get_type() == MoveType::Quiet {
+                    -see_quiet_margin() * depth as Score
+                } else {
+                    -see_tactical_margin() * depth as Score
+                };
+
+                if !pos.board.see(mv, margin) {
+                    continue;
+                }
             }
 
             ////////////////////////////////////////////////////////////////////
diff --git a/simbelmyne/src/search/params.rs b/simbelmyne/src/search/params.rs
index 6f614b7..4e64d60 100644
--- a/simbelmyne/src/search/params.rs
+++ b/simbelmyne/src/search/params.rs
@@ -143,6 +143,9 @@ pub mod tunable_params {
     #[uci(min = 0, max = 200, step = 10)]
     const SEE_QUIET_MARGIN: i32 = 40;
 
+    #[uci(min = 0, max = 200, step = 10)]
+    const SEE_TACTICAL_MARGIN: i32 = 100;
+
     ////////////////////////////////////////////////////////////////////////////
     //
     // Singular extensions