[Polly] Remove dead code in IndependentBlocks

[Meinersbur]

Summary

The splitExitBlock function is never called. Going to replace its functionality in successive patches that do not modify the IR.

[grosser]

This looks good to me.

Michael, this change is simple/trivial enough that you do not need a pre-commit review. You can just commit and rely on post-commit review for the unlikely case that somebody has some additional
comments.

lib/Transform/IndependentBlocks.cpp

struct IndependentBlocks : public FunctionPass {
   /// @param InsertPos    The insert position of the moved instructions.
   void moveOperandTree(Instruction *Inst, const Region *R,
                        ReplacedMapType &ReplacedMap, Instruction *InsertPos);
 
   bool isIndependentBlock(const Region *R, BasicBlock *BB) const;
   bool areAllBlocksIndependent(const Region *R) const;
 
   // Split the exit block to hold load instructions.
-  bool splitExitBlock(Region *R);
   bool onlyUsedInRegion(Instruction *Inst, const Region *R);
   bool translateScalarToArray(BasicBlock *BB, const Region *R);
   bool translateScalarToArray(Instruction *Inst, const Region *R);
   bool translateScalarToArray(const Region *R);
 
   bool runOnFunction(Function &F);
   void verifyAnalysis() const;
   void verifyScop(const Region *R) const;
bool IndependentBlocks::isEscapeOperand(const Value *Operand,
   // Induction variables are valid operands.
   if (canSynthesize(OpInst, LI, SE, R))
     return false;
 
   // A value from a different BB is used in the same region.
   return R->contains(OpInst) && (OpInst->getParent() != CurBB);
 }
 
-bool IndependentBlocks::splitExitBlock(Region *R) {
-  // Split the exit BB to place the load instruction of escaped users.
-  BasicBlock *ExitBB = R->getExit();
-  Region *ExitRegion = RI->getRegionFor(ExitBB);
-
-  if (ExitBB != ExitRegion->getEntry())
-    return false;
-
-  BasicBlock *NewExit = createSingleExitEdge(R, this);
-
-  std::vector<Region *> toUpdate;
-  toUpdate.push_back(R);
-
-  while (!toUpdate.empty()) {
-    Region *R = toUpdate.back();
-    toUpdate.pop_back();
-
-    for (auto &&SubRegion : *R)
-      if (SubRegion->getExit() == ExitBB)
-        toUpdate.push_back(SubRegion.get());
-
-    R->replaceExit(NewExit);
-  }
-
-  RI->setRegionFor(NewExit, R->getParent());
-  return true;
-}
-
 bool IndependentBlocks::translateScalarToArray(const Region *R) {
   bool Changed = false;
 
   for (BasicBlock *BB : R->blocks())
     Changed |= translateScalarToArray(BB, R);
 
   return Changed;
 }