[llvm] [ExtendLifetimes] Implement llvm.fake.use to extend variable lifetimes (PR #86149)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,54 @@
+; RUN: opt -S -passes=sroa %s | FileCheck %s
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arsenm wrote:

This should go in test/Transforms/SROA, not codegen 

https://github.com/llvm/llvm-project/pull/86149