Add Chromium-only Blender WebEngine parity work

blender-5.2.0/source/blender/blenlib/BLI_unroll.hh

@@ -0,0 +1,32 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup bli
+ */
+
+#pragma once
+
+#include <cstdlib>
+#include <utility>
+
+namespace blender {
+
+template<class Fn, size_t... I>
+constexpr void unroll_impl(Fn fn, std::index_sequence<I...> /*indices*/)
+{
+  (fn(I), ...);
+}
+
+/**
+ * Variadic templates are used to unroll loops manually. This helps GCC avoid branching during math
+ * operations and makes the code generation more explicit and predictable. Unrolling should always
+ * be worth it because the vector size is expected to be small.
+ */
+template<int N, class Fn> constexpr void unroll(Fn fn)
+{
+  unroll_impl(fn, std::make_index_sequence<N>());
+}
+
+}  // namespace blender