[llvm] [VPlan] Make canonical IV part of the region (PR #156262)

[via llvm-commits]

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@@ -3992,6 +3926,32 @@ class VPIRBasicBlock : public VPBasicBlock {
   BasicBlock *getIRBasicBlock() const { return IRBB; }
 };
 
+/// Track information about the canonical IV value of a region.
+class VPCanonicalIVInfo {
+  /// VPRegionValue for the canonical IV. The allocation is managed by
+  /// VPCanonicalIVInfo.
+  std::unique_ptr<VPRegionValue> CanIV;
+  Type *Ty = nullptr;
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ayalz wrote:

Should VPRegionValue hold its Type? Its DL?

https://github.com/llvm/llvm-project/pull/156262