!fixup address latest comments, thanks!

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -989,9 +989,11 @@ void VPlan::prepareToExecute(Value *TripCountV, Value *VectorTripCountV,
 }
 
 VPIRBasicBlock *VPlan::getExitBlock(BasicBlock *IRBB) const {
-  return *find_if(getExitBlocks(), [IRBB](const VPIRBasicBlock *VPIRBB) {
+  auto Iter = find_if(getExitBlocks(), [IRBB](const VPIRBasicBlock *VPIRBB) {
     return VPIRBB->getIRBasicBlock() == IRBB;
   });
+  assert(Iter != getExitBlocks().end() && "no exit block found");
+  return *Iter;
 }
 
 bool VPlan::isExitBlock(VPBlockBase *VPBB) {

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -3427,8 +3427,8 @@ class VPlan {
   VPIRBasicBlock *ScalarHeader;
 
   /// Immutable list of VPIRBasicBlocks wrapping the exit blocks of the original
-  /// scalar loop. Note that some exit blocks may be unreachable, e.g. if the
-  /// scalar epilogue always executes
+  /// scalar loop. Note that some exit blocks may be unreachable at the moment,
+  /// e.g. if the scalar epilogue always executes.
   SmallVector<VPIRBasicBlock *, 2> ExitBlocks;
 
   /// Holds the VFs applicable to this VPlan.