[llvm] Improvements to RS4GC BDV Algorithm (PR #69795)

[via llvm-commits]

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@@ -1012,8 +1012,44 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &Cache,
   }
 #endif
 
-  // Handle all instructions that have a vector BDV, but the instruction itself
-  // is of scalar type.
+  // Even though we have identified a concrete base (or a conflict) for all live
+  // pointers at this point, there are cases where the base is of an
+  // incompatible type compared to the original instruction. We conservatively
+  // mark those as conflicts to ensure that corresponding BDVs will be generated
+  // in the next steps
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annamthomas wrote:

```suggestion
  // in the next steps.
```

https://github.com/llvm/llvm-project/pull/69795