[llvm] [LiveVariables] Mark use as implicit-def if defined at instr (PR #119446)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,46 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn --run-pass=livevars -o - %s | FileCheck %s
+---
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arsenm wrote:

Comment the purpose of the test 

https://github.com/llvm/llvm-project/pull/119446