[llvm] [AMDGPU] Add amdgpu-lower-exec-sync pass to lower named-barrier globals (PR #165692)

[Sameer Sahasrabuddhe via llvm-commits]

================
@@ -0,0 +1,241 @@
+//===-- AMDGPULowerExecSync.cpp -----------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// AMDGPU Lower Execution Synchronization pass performs lowering of
----------------
ssahasra wrote:

```suggestion
// Lower
```

https://github.com/llvm/llvm-project/pull/165692