[llvm] Make RAUW skip instances where operand is the replacement node (PR #212724)

[Matt Arsenault via llvm-commits]

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@@ -1,14 +1,16 @@
-; RUN: llc < %s -mtriple=x86_64 -mattr=+avx2 -o /dev/null
+; RUN: llc < %s -o /dev/null
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arsenm wrote:

Don't discard the output, use update_llc_test_checks 

https://github.com/llvm/llvm-project/pull/212724