From b0fcd55aed210cb9aa4a9724123e63a2aa248b16 Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brecht@blender.org>
Date: Thu, 20 Feb 2025 16:32:44 +0100
Subject: [PATCH] Fix: Cycles OSL random texture issue on macOS ARM

Shader compilation is multithreaded, this needs to be atomic.

Pull Request: https://projects.blender.org/blender/blender/pulls/134854
---
 intern/cycles/scene/osl.cpp | 2 +-
 intern/cycles/scene/osl.h   | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/intern/cycles/scene/osl.cpp b/intern/cycles/scene/osl.cpp
index 5bc5fe58cba..0364393f7fd 100644
--- a/intern/cycles/scene/osl.cpp
+++ b/intern/cycles/scene/osl.cpp
@@ -48,7 +48,7 @@ map<int, unique_ptr<OSL::ShadingSystem>> OSLShaderManager::ss_shared;
 int OSLShaderManager::ss_shared_users = 0;
 thread_mutex OSLShaderManager::ss_shared_mutex;
 
-int OSLCompiler::texture_shared_unique_id = 0;
+std::atomic<int> OSLCompiler::texture_shared_unique_id = 0;
 
 /* Shader Manager */
 
diff --git a/intern/cycles/scene/osl.h b/intern/cycles/scene/osl.h
index bf6d260f292..ba4e88fbaac 100644
--- a/intern/cycles/scene/osl.h
+++ b/intern/cycles/scene/osl.h
@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <atomic>
+
 #include "util/array.h"
 #include "util/set.h"
 #include "util/string.h"
@@ -180,7 +182,7 @@ class OSLCompiler {
   ShaderType current_type;
   Shader *current_shader;
 
-  static int texture_shared_unique_id;
+  static std::atomic<int> texture_shared_unique_id;
 };
 
 CCL_NAMESPACE_END