[RegionInfo] Remove unused and broken function splitBlock

[Meinersbur]

Summary

It always makes NewBB the entry of the region instead of OldBB. This breaks if there are edges from inside the region to OldBB. OldBB is moved out of the region and hence there are exiting edges to OldBB and the region's exit block, contradicting the single-exit condition for regions.

The only use from Polly is going to be removed, hence I propose to remove the function completely.

[grosser]

Michael, I think you can drop this if all users are removed.

Tobias

[Meinersbur]

User in Polly has been removed

llvm/trunk/include/llvm/Analysis/RegionInfo.h

#endif
   /// @brief Find the smallest region that contains a set of basic blocks.
   ///
   /// @param BBs A vector of basic blocks.
   /// @return The smallest region that contains all basic blocks in BBS.
   RegionT *getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const;
 
   RegionT *getTopLevelRegion() const { return TopLevelRegion; }
 
-  /// @brief Update RegionInfo after a basic block was split.
-  ///
-  /// @param NewBB The basic block that was created before OldBB.
-  /// @param OldBB The old basic block.
-  void splitBlock(BlockT *NewBB, BlockT *OldBB);
-
   /// @brief Clear the Node Cache for all Regions.
   ///
   /// @see Region::clearNodeCache()
   void clearNodeCache() {
     if (TopLevelRegion)
       TopLevelRegion->clearNodeCache();
   }
 

llvm/trunk/include/llvm/Analysis/RegionInfoImpl.h

RegionInfoBase<Tr>::getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const {
 
   for (BlockT *BB : BBs)
     ret = getCommonRegion(ret, getRegionFor(BB));
 
   return ret;
 }
 
 template <class Tr>
-void RegionInfoBase<Tr>::splitBlock(BlockT *NewBB, BlockT *OldBB) {
-  RegionT *R = getRegionFor(OldBB);
-
-  setRegionFor(NewBB, R);
-
-  while (R->getEntry() == OldBB && !R->isTopLevelRegion()) {
-    R->replaceEntry(NewBB);
-    R = R->getParent();
-  }
-
-  setRegionFor(OldBB, R);
-}
-
-template <class Tr>
 void RegionInfoBase<Tr>::calculate(FuncT &F) {
   typedef typename std::add_pointer<FuncT>::type FuncPtrT;
 
   // ShortCut a function where for every BB the exit of the largest region
   // starting with BB is stored. These regions can be threated as single BBS.
   // This improves performance on linear CFGs.
   BBtoBBMap ShortCut;