[llvm] [InstSimplify] Add roundeven constant-propagation tests (PR #170688)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,165 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -S -passes=early-cse -earlycse-debug-hash < %s | FileCheck %s
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nikic wrote:

```suggestion
; RUN: opt -S -passes=instsimplify < %s | FileCheck %s
```

https://github.com/llvm/llvm-project/pull/170688