[llvm] [RFC][IR] Support vector splats in `ConstantPointerNull` (PR #195486)

[Matt Arsenault via llvm-commits]

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@@ -2001,11 +2041,19 @@ ConstantRange Constant::toConstantRange() const {
 //
 
 ConstantPointerNull *ConstantPointerNull::get(PointerType *Ty) {
+  return get(static_cast<Type *>(Ty));
+}
+
+ConstantPointerNull *ConstantPointerNull::get(Type *Ty) {
+  assert((Ty->isPointerTy() ||
+          (Ty->isVectorTy() && Ty->getScalarType()->isPointerTy())) &&
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arsenm wrote:

```suggestion
  assert((Ty->isPtrOrPtrVectorTy() &&
```

https://github.com/llvm/llvm-project/pull/195486