[llvm] [CodeGen] Port AtomicExpand to new Pass Manager (PR #71220)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,35 @@
+//===- AtomicExpand.h ------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+///
+///
+//===----------------------------------------------------------------------===//
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arsenm wrote:

Drop empty comment block 

https://github.com/llvm/llvm-project/pull/71220