!fixup address comments, thanks

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp

@@ -491,6 +491,9 @@ void VPlanTransforms::prepareForVectorization(
                         cast<VPBasicBlock>(LatchVPB), InductionTy, IVDL);
 
   [[maybe_unused]] bool HandledUncountableEarlyExit = false;
+  // Handle the remaining early exits, either by converting the plan to one only
+  // exiting via the latch or by disconnecting all early exiting edges and
+  // requiring a scalar epilogue.
   for (VPIRBasicBlock *EB : Plan.getExitBlocks()) {
     for (VPBlockBase *Pred : to_vector(EB->getPredecessors())) {
       if (Pred == MiddleVPBB)

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -2472,6 +2472,9 @@ void VPlanTransforms::handleUncountableEarlyExit(VPBasicBlock *EarlyExitingVPBB,
   VPBlockBase *MiddleVPBB = LatchVPBB->getSuccessors()[0];
   if (!EarlyExitVPBB->getSinglePredecessor() &&
       EarlyExitVPBB->getPredecessors()[0] != MiddleVPBB) {
+    assert(EarlyExitVPBB->getNumPredecessors() == 2 &&
+           EarlyExitVPBB->getPredecessors()[1] == MiddleVPBB &&
+           "unsupported earl exit VPBB");
     // Early exit operand should always be last phi operand. If EarlyExitVPBB
     // has two predecessors and MiddleVPBB isn't the first, swap the operands of
     // the phis.