[llvm] [VPlan] Add exit phi operands during initial construction (NFC). (PR #136455)

[via llvm-commits]

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@@ -352,6 +352,19 @@ std::unique_ptr<VPlan> PlainCFGBuilder::buildPlainCFG(
   Plan->getEntry()->setOneSuccessor(getOrCreateVPBB(TheLoop->getHeader()));
   Plan->getEntry()->setPlan(&*Plan);
 
+  // Add incoming operands for the VPIRInstructions wrapping the exit phis.
+  for (auto *EB : Plan->getExitBlocks()) {
+    for (VPRecipeBase &R : *EB) {
+      auto *PhiR = dyn_cast<VPIRPhi>(&R);
+      if (!PhiR)
+        break;
+      PHINode &Phi = PhiR->getIRPhi();
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ayalz wrote:

assert PhiR is still w/o any operand?

https://github.com/llvm/llvm-project/pull/136455