[llvm] [RemoveDIs][DebugInfo] Add DPValue checks to the verifier, prepare DPValue for parsing support (PR #79810)

[Stephen Tozer via llvm-commits]

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@@ -81,7 +81,7 @@ class DPValue : public ilist_node<DPValue>, private DebugValueUser {
   // DebugValueUser superclass instead. The referred to Value can either be a
   // ValueAsMetadata or a DIArgList.
 
-  DILocalVariable *Variable;
+  TrackingMDNodeRef Variable;
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SLTozer wrote:

Correct - it's just a wrapped `Metadata*`.

https://github.com/llvm/llvm-project/pull/79810