JumpThreading.cpp

        continue;
      
      UsesToRename.push_back(&UI.getUse());
    }
    
    // If there are no uses outside the block, we're done with this instruction.
    if (UsesToRename.empty())
      continue;
    
    DEBUG(errs() << "JT: Renaming non-local uses of: " << *I << "\n");

    // We found a use of I outside of BB.  Rename all uses of I that are outside
    // its block to be uses of the appropriate PHI node etc.  See ValuesInBlocks
    // with the two values we know.
    SSAUpdate.Initialize(I);
    SSAUpdate.AddAvailableValue(BB, I);
    SSAUpdate.AddAvailableValue(NewBB, ValueMapping[I]);
    
    while (!UsesToRename.empty())
      SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
    DEBUG(errs() << "\n");
  }
  
  
  // Ok, NewBB is good to go.  Update the terminator of PredBB to jump to
  // NewBB instead of BB.  This eliminates predecessors from BB, which requires
  // us to simplify any PHI nodes in BB.
  TerminatorInst *PredTerm = PredBB->getTerminator();
  for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i)
    if (PredTerm->getSuccessor(i) == BB) {
      BB->removePredecessor(PredBB);
      PredTerm->setSuccessor(i, NewBB);
    }
  
  // At this point, the IR is fully up to date and consistent.  Do a quick scan
  // over the new instructions and zap any that are constants or dead.  This
  // frequently happens because of phi translation.
  BI = NewBB->begin();
  for (BasicBlock::iterator E = NewBB->end(); BI != E; ) {
    Instruction *Inst = BI++;
    if (Constant *C = ConstantFoldInstruction(Inst, BB->getContext(), TD)) {
      Inst->replaceAllUsesWith(C);
      Inst->eraseFromParent();
      continue;
    }
    
    RecursivelyDeleteTriviallyDeadInstructions(Inst);
  }
  
  // Threaded an edge!
  ++NumThreads;
  return true;
}