[llvm] [VPlan] Fold VPDef into VPRecipeBase (NFC). (PR #174282)

[via llvm-commits]

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@@ -211,11 +208,17 @@ struct VPSymbolicValue : public VPValue {
 class VPRecipeValue : public VPValue {
   friend class VPValue;
   friend class VPDef;
-  /// Pointer to the VPDef that defines this VPValue.
-  VPDef *Def;
+
+  /// Pointer to the VPRecipeBase that defines this VPValue.
+  VPRecipeBase *Def;
+
+#if !defined(NDEBUG)
+  /// Returns true if this VPRecipeValue is defined by \p D.
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ayalz wrote:

Good to leave behind a note that isDefinedBy() is needed only for asserting that the VPRecipeValues added or removed from a VPDef are associated with its VPRecipeBase, before the latter is defined; which is also why it is implemented in VPlan.cpp rather than inline here.

https://github.com/llvm/llvm-project/pull/174282