[llvm] [llvm] Migrate away from PointerUnion::{is, get, dyn_cast} (NFC) (PR #115626)

[Kazu Hirata via llvm-commits]

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@@ -1052,9 +1052,9 @@ class AssignmentTrackingLowering {
       if (Source.isNull())
         OS << "null";
       else if (isa<DbgAssignIntrinsic *>(Source))
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kazutakahirata wrote:

That's much cleaner.  Thanks!  Updated in the latest revision.

https://github.com/llvm/llvm-project/pull/115626