[llvm] [VPlan] Simplify branch on False in VPlan transform (NFC). (PR #140409)

[via llvm-commits]

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@@ -2379,13 +2379,15 @@ void InnerLoopVectorizer::introduceCheckBlockInVPlan(BasicBlock *CheckIRBB) {
   PreVectorPH->swapSuccessors();
 
   // We just connected a new block to the scalar preheader. Update all
-  // ResumePhis by adding an incoming value for it, replicating the last value.
-  for (VPRecipeBase &R : *cast<VPBasicBlock>(ScalarPH)) {
-    auto *ResumePhi = dyn_cast<VPInstruction>(&R);
-    if (!ResumePhi || ResumePhi->getOpcode() != VPInstruction::ResumePhi)
-      continue;
+  // VPPhis by adding an incoming value for it, replicating the last value.
+  unsigned NumPredecessors = ScalarPH->getNumPredecessors();
+  (void)NumPredecessors;
+  for (VPRecipeBase &R : cast<VPBasicBlock>(ScalarPH)->phis()) {
+    auto *ResumePhi = cast<VPPhi>(&R);
     ResumePhi->addOperand(
         ResumePhi->getOperand(ResumePhi->getNumOperands() - 1));
+    assert(ResumePhi->getNumIncoming() == NumPredecessors &&
+           "must have incoming values for all operands");
----------------
ayalz wrote:

```suggestion
  for (VPRecipeBase &R : cast<VPBasicBlock>(ScalarPH)->phis()) {
    assert(isa<VPPhi>(&R) && "Phi expected to be VPPhi");
    assert(cast<VPPhi>(&R)->getNumIncoming() == NumPredecessors - 1 &&
           "must have incoming values for all operands");
    R->addOperand(R->getOperand(NumPredecessors - 1));
```

https://github.com/llvm/llvm-project/pull/140409