[llvm] [LLVM][IR] Support target extension types in vectors (PR #140630)

[Nikita Popov via llvm-commits]

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@@ -4438,7 +4438,8 @@ the type size is smaller than the type's store size.
       < vscale x <# elements> x <elementtype> > ; Scalable vector
 
 The number of elements is a constant integer value larger than 0;
-elementtype may be any integer, floating-point or pointer type. Vectors
+elementtype may be any integer, floating-point, pointer type, or a sized  
+target extension type that has the `CanBeVectorElement` property. Vectors
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nikic wrote:

```suggestion
target extension type that has the ``CanBeVectorElement`` property. Vectors
```

https://github.com/llvm/llvm-project/pull/140630