[llvm] [VPlan] Make CanIV part of region. (PR #144803)

[via llvm-commits]

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@@ -441,7 +437,11 @@ SmallVector<VPRegisterUsage, 8> llvm::calculateRegisterUsageForPlan(
   // first and last occurrences of each recipe.
   ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
       Plan.getVectorLoopRegion());
-  for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
+  for (VPBlockBase *VPB : RPOT) {
+    if (auto *R = dyn_cast<VPRegionBlock>(VPB)) {
+      continue;
+    }
+    auto *VPBB = cast<VPBasicBlock>(VPB);
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ayalz wrote:

Same as current `VPBlockUtils::blocksOnly<VPBasicBlock>`?

https://github.com/llvm/llvm-project/pull/144803