[llvm] [CodeGenPrepare] Preserve flags (such as nsw/nuw) in SinkCast (PR #89904)

[Alex Bradbury via llvm-commits]

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@@ -0,0 +1,30 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes='require<profile-summary>,function(codegenprepare)' -mtriple=riscv64 %s \
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asb wrote:

Seems the ugly workaround was noted in #75380 when CodeGenPrepare was ported to the new pass manager.

https://github.com/llvm/llvm-project/pull/89904