[llvm] [ARM] Add pass for handling undef early-clobber values (PR #77770)

[Jack Styles via llvm-commits]

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@@ -0,0 +1,242 @@
+//===- ARMInitUndef.cpp - Initialize undef vector value to pseudo -------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass runs to allow for Undef values to be given a definition in
+// early-clobber instructions. This can occur when using higher levels of
+// optimisations. Before, undef values were ignored and it would result in
+// early-clobber instructions using the same registeres for the output as one of
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Stylie777 wrote:

Fixed this, although I think the comment has now been removed. 

https://github.com/llvm/llvm-project/pull/77770