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

[Florian Hahn via llvm-commits]

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@@ -4067,6 +4030,13 @@ class LLVM_ABI_FOR_TEST VPRegionBlock : public VPBlockBase {
   /// Remove the current region from its VPlan, connecting its predecessor to
   /// its entry, and its exiting block to its successor.
   void dissolveToCFGLoop();
+
+  /// Return the canonical induction variable of the region, null for
+  /// replicating regions.
+  VPValue *getCanonicalIV() { return CanIVInfo.CanIV; }
+  const VPValue *getCanonicalIV() const { return CanIVInfo.CanIV; }
+
+  VPCanonicalIVInfo &getCanonicalIVInfo() { return CanIVInfo; }
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fhahn wrote:

For now yes, it is currenetly used to clear NUW, but could also be moved to accessor.

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