!fixup restore part of assert and fix formatting

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -862,8 +862,12 @@ VPlanPtr VPlan::createInitialVPlan(Type *InductionTy,
   VPIRBasicBlock *Entry =
       VPIRBasicBlock::fromBasicBlock(TheLoop->getLoopPreheader());
   VPBasicBlock *VecPreheader = new VPBasicBlock("vector.ph");
-  // Connect entry only to vector preheader initially. Entry will also be connected to the scalar preheader later, during skeleton creation when runtime guards are added as needed.
-  // Note that when executing the VPlan for an epilogue vector loop, the original entry block here will be replaced by a new VPIRBasicBlock wrapping the entry to the epilogue vector loop after generating code for the main vector loop.
+  // Connect entry only to vector preheader initially. Entry will also be
+  // connected to the scalar preheader later, during skeleton creation when
+  // runtime guards are added as needed. Note that when executing the VPlan for
+  // an epilogue vector loop, the original entry block here will be replaced by
+  // a new VPIRBasicBlock wrapping the entry to the epilogue vector loop after
+  // generating code for the main vector loop.
   VPBlockUtils::connectBlocks(Entry, VecPreheader);
   VPIRBasicBlock *ScalarHeader =
       VPIRBasicBlock::fromBasicBlock(TheLoop->getHeader());

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -3845,7 +3845,9 @@ class VPlan {
 
   /// Create initial VPlan, having an "entry" VPBasicBlock (wrapping
   /// original scalar pre-header) which contains SCEV expansions that need
-  /// to happen before the CFG is modified (when executing a VPlan for the epilogue vector loop, the original entry needs to be replaced by the new entry for the epilogue vector loop); a VPBasicBlock for the vector
+  /// to happen before the CFG is modified (when executing a VPlan for the
+  /// epilogue vector loop, the original entry needs to be replaced by the new
+  /// entry for the epilogue vector loop); a VPBasicBlock for the vector
   /// pre-header, followed by a region for the vector loop, followed by the
   /// middle VPBasicBlock. If a check is needed to guard executing the scalar
   /// epilogue loop, it will be added to the middle block, together with
@@ -4176,6 +4178,8 @@ class VPBlockUtils {
                             unsigned PredIdx = -1u, unsigned SuccIdx = -1u) {
     assert((From->getParent() == To->getParent()) &&
            "Can't connect two block with different parents");
+    assert((SuccIdx != -1u || From->getNumSuccessors() < 2) &&
+        "Blocks can't have more than two successors.");
     if (SuccIdx == -1u)
       From->appendSuccessor(To);
     else