From bb5f0100b033d7b337a7eb1a3ebcfd7619bd9f00 Mon Sep 17 00:00:00 2001
From: Ryan Lefkowitz <rlefkowitz1800@yahoo.com>
Date: Wed, 15 Apr 2026 19:03:55 +0200
Subject: [PATCH] fix syzygy crash on Apple Silicon by unrolling tbprobe
 adjustment loop

A bit tricky to identify, but in `apple-silicon` builds, specifying a value for
`SyzygyPath` could still lead to crashes at certain depths from a
SIGBUS/SIGSEGV.

This PR replaces the `std::count_if()` adjustment in `tbprobe.cpp`'s
`do_probe_table()` with an annotated handwritten loop, avoiding the clang/LTO
miscompilation behind the crash.

closes https://github.com/official-stockfish/Stockfish/pull/6721

No functional change.
---
 AUTHORS                | 1 +
 src/syzygy/tbprobe.cpp | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index 0d157b655..1f0b9e37c 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -223,6 +223,7 @@ Ron Britvich (Britvich)
 rqs
 Rui Coelho (ruicoelhopedro)
 rustam-cpp
+Ryan Lefkowitz (rlefko)
 Ryan Hirsch
 Ryan Schmitt
 Ryan Takker
diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp
index ba808ee4b..b75b6046a 100644
--- a/src/syzygy/tbprobe.cpp
+++ b/src/syzygy/tbprobe.cpp
@@ -949,8 +949,10 @@ encode_remaining:
         // groups (similar to what was done earlier for leading group pieces).
         for (int i = 0; i < d->groupLen[next]; ++i)
         {
-            auto f      = [&](Square s) { return groupSq[i] > s; };
-            auto adjust = std::count_if(squares, groupSq, f);
+            int adjust = 0;
+            DISABLE_CLANG_LOOP_VEC
+            for (Square* sq = squares; sq != groupSq; ++sq)
+                adjust += groupSq[i] > *sq;
             n += Binomial[i + 1][groupSq[i] - adjust - 8 * remainingPawns];
         }