[KeyInstr] Fix llvm#139070 for empty DebugLocs

Author: OCHyams

llvm/lib/IR/BasicBlock.cpp

@@ -609,7 +609,10 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName,
                                        this->getNextNode());
 
   // Save DebugLoc of split point before invalidating iterator.
-  DebugLoc Loc = I->getStableDebugLoc()->getWithoutAtom();
+  DebugLoc Loc = I->getStableDebugLoc();
+  if (Loc)
+    Loc = Loc->getWithoutAtom();
+
   // Move all of the specified instructions from the original basic block into
   // the new basic block.
   New->splice(New->end(), this, I, end());
@@ -638,7 +641,10 @@ BasicBlock *BasicBlock::splitBasicBlockBefore(iterator I, const Twine &BBName) {
 
   BasicBlock *New = BasicBlock::Create(getContext(), BBName, getParent(), this);
   // Save DebugLoc of split point before invalidating iterator.
-  DebugLoc Loc = I->getDebugLoc()->getWithoutAtom();
+  DebugLoc Loc = I->getDebugLoc();
+  if (Loc)
+    Loc = Loc->getWithoutAtom();
+
   // Move all of the specified instructions from the original basic block into
   // the new basic block.
   New->splice(New->end(), this, begin(), I);