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

[Alexander Richardson via llvm-commits]

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@@ -48,6 +48,22 @@ static cl::opt<bool> UseConstantIntForScalableSplat(
 static cl::opt<bool> UseConstantFPForScalableSplat(
     "use-constant-fp-for-scalable-splat", cl::init(true), cl::Hidden,
     cl::desc("Use ConstantFP's native scalable vector splat support."));
+static cl::opt<bool> UseConstantPtrNullForFixedLengthSplat(
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arichardson wrote:

Are these options used anywhere? Is this for downstream migration purposes? If so there should be a comment, and if not maybe best to not add any not options that aren't strictly needed. 

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