[clang] [llvm] [SPIRV] add pre legalization instruction combine (PR #122839)

[Michal Paszkowski via llvm-commits]

================
@@ -0,0 +1,26 @@
+//=- SPIRVCombine.td - Define SPIRV Combine Rules -------------*-tablegen -*-=//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
----------------
michalpaszkowski wrote:

Should the file include some comment? Otherwise, I think this part could be removed.

https://github.com/llvm/llvm-project/pull/122839