C++ CaseIt::getCaseSuccessor方法代码示例

void LLVM_General_GetSwitchCases(
	LLVMValueRef v,
	LLVMValueRef *values,
	LLVMBasicBlockRef *dests
) {
	SwitchInst *s = unwrap<SwitchInst>(v);
	for(SwitchInst::CaseIt i = s->case_begin(); i != s->case_end(); ++i, ++values, ++dests) {
		*values = wrap(i.getCaseValue());
		*dests = wrap(i.getCaseSuccessor());
	}
}

// processSwitchInst - Replace the specified switch instruction with a sequence
// of chained if-then instructions.
//
void LowerSwitchPass::processSwitchInst(SwitchInst *SI) {
  BasicBlock *origBlock = SI->getParent();
  BasicBlock *defaultBlock = SI->getDefaultDest();
  Function *F = origBlock->getParent();
  Value *switchValue = SI->getCondition();

  // Create a new, empty default block so that the new hierarchy of
  // if-then statements go to this and the PHI nodes are happy.
  BasicBlock* newDefault = BasicBlock::Create(getGlobalContext(), "newDefault");

#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 8)
  F->getBasicBlockList().insert(defaultBlock->getIterator(), newDefault);
#else
  F->getBasicBlockList().insert(defaultBlock, newDefault);
#endif
  BranchInst::Create(defaultBlock, newDefault);

  // If there is an entry in any PHI nodes for the default edge, make sure
  // to update them as well.
  for (BasicBlock::iterator I = defaultBlock->begin(); isa<PHINode>(I); ++I) {
    PHINode *PN = cast<PHINode>(I);
    int BlockIdx = PN->getBasicBlockIndex(origBlock);
    assert(BlockIdx != -1 && "Switch didn't go to this successor??");
    PN->setIncomingBlock((unsigned)BlockIdx, newDefault);
  }
  
  CaseVector cases;
  
#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 1)
  for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
    cases.push_back(SwitchCase(i.getCaseValue(),
                               i.getCaseSuccessor()));
#else
  for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)  
    cases.push_back(SwitchCase(SI->getSuccessorValue(i),
                               SI->getSuccessor(i)));
#endif
  
  // reverse cases, as switchConvert constructs a chain of
  //   basic blocks by appending to the front. if we reverse,
  //   the if comparisons will happen in the same order
  //   as the cases appear in the switch
  std::reverse(cases.begin(), cases.end());
  
  switchConvert(cases.begin(), cases.end(), switchValue, origBlock, newDefault);

  // We are now done with the switch instruction, so delete it
  origBlock->getInstList().erase(SI);
}

/// processSwitch - Simplify a switch instruction by removing cases which can
/// never fire.  If the uselessness of a case could be determined locally then
/// constant propagation would already have figured it out.  Instead, walk the
/// predecessors and statically evaluate cases based on information available
/// on that edge.  Cases that cannot fire no matter what the incoming edge can
/// safely be removed.  If a case fires on every incoming edge then the entire
/// switch can be removed and replaced with a branch to the case destination.
bool CorrelatedValuePropagation::processSwitch(SwitchInst *SI) {
  Value *Cond = SI->getCondition();
  BasicBlock *BB = SI->getParent();

  // If the condition was defined in same block as the switch then LazyValueInfo
  // currently won't say anything useful about it, though in theory it could.
  if (isa<Instruction>(Cond) && cast<Instruction>(Cond)->getParent() == BB)
    return false;

  // If the switch is unreachable then trying to improve it is a waste of time.
  pred_iterator PB = pred_begin(BB), PE = pred_end(BB);
  if (PB == PE) return false;

  // Analyse each switch case in turn.  This is done in reverse order so that
  // removing a case doesn't cause trouble for the iteration.
  bool Changed = false;
  for (SwitchInst::CaseIt CI = SI->case_end(), CE = SI->case_begin(); CI-- != CE;
       ) {
    ConstantInt *Case = CI.getCaseValue();

    // Check to see if the switch condition is equal to/not equal to the case
    // value on every incoming edge, equal/not equal being the same each time.
    LazyValueInfo::Tristate State = LazyValueInfo::Unknown;
    for (pred_iterator PI = PB; PI != PE; ++PI) {
      // Is the switch condition equal to the case value?
      LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ,
                                                              Cond, Case, *PI,
                                                              BB, SI);
      // Give up on this case if nothing is known.
      if (Value == LazyValueInfo::Unknown) {
        State = LazyValueInfo::Unknown;
        break;
      }

      // If this was the first edge to be visited, record that all other edges
      // need to give the same result.
      if (PI == PB) {
        State = Value;
        continue;
      }

      // If this case is known to fire for some edges and known not to fire for
      // others then there is nothing we can do - give up.
      if (Value != State) {
        State = LazyValueInfo::Unknown;
        break;
      }
    }

    if (State == LazyValueInfo::False) {
      // This case never fires - remove it.
      CI.getCaseSuccessor()->removePredecessor(BB);
      SI->removeCase(CI); // Does not invalidate the iterator.

      // The condition can be modified by removePredecessor's PHI simplification
      // logic.
      Cond = SI->getCondition();

      ++NumDeadCases;
      Changed = true;
    } else if (State == LazyValueInfo::True) {
      // This case always fires.  Arrange for the switch to be turned into an
      // unconditional branch by replacing the switch condition with the case
      // value.
      SI->setCondition(Case);
      NumDeadCases += SI->getNumCases();
      Changed = true;
      break;
    }
  }

  if (Changed)
    // If the switch has been simplified to the point where it can be replaced
    // by a branch then do so now.
    ConstantFoldTerminator(BB);

  return Changed;
}

/// \brief Compute the value of Val on the edge BBFrom -> BBTo. Returns false if
/// Val is not constrained on the edge.
static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
                              BasicBlock *BBTo, LVILatticeVal &Result) {
  // TODO: Handle more complex conditionals.  If (v == 0 || v2 < 1) is false, we
  // know that v != 0.
  if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) {
    // If this is a conditional branch and only one successor goes to BBTo, then
    // we maybe able to infer something from the condition. 
    if (BI->isConditional() &&
        BI->getSuccessor(0) != BI->getSuccessor(1)) {
      bool isTrueDest = BI->getSuccessor(0) == BBTo;
      assert(BI->getSuccessor(!isTrueDest) == BBTo &&
             "BBTo isn't a successor of BBFrom");
      
      // If V is the condition of the branch itself, then we know exactly what
      // it is.
      if (BI->getCondition() == Val) {
        Result = LVILatticeVal::get(ConstantInt::get(
                              Type::getInt1Ty(Val->getContext()), isTrueDest));
        return true;
      }
      
      // If the condition of the branch is an equality comparison, we may be
      // able to infer the value.
      ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition());
      if (ICI && isa<Constant>(ICI->getOperand(1))) {
        if (ICI->isEquality() && ICI->getOperand(0) == Val) {
          // We know that V has the RHS constant if this is a true SETEQ or
          // false SETNE. 
          if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
            Result = LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
          else
            Result = LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
          return true;
        }

        // Recognize the range checking idiom that InstCombine produces.
        // (X-C1) u< C2 --> [C1, C1+C2)
        ConstantInt *NegOffset = 0;
        if (ICI->getPredicate() == ICmpInst::ICMP_ULT)
          match(ICI->getOperand(0), m_Add(m_Specific(Val),
                                          m_ConstantInt(NegOffset)));

        ConstantInt *CI = dyn_cast<ConstantInt>(ICI->getOperand(1));
        if (CI && (ICI->getOperand(0) == Val || NegOffset)) {
          // Calculate the range of values that would satisfy the comparison.
          ConstantRange CmpRange(CI->getValue());
          ConstantRange TrueValues =
            ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange);

          if (NegOffset) // Apply the offset from above.
            TrueValues = TrueValues.subtract(NegOffset->getValue());

          // If we're interested in the false dest, invert the condition.
          if (!isTrueDest) TrueValues = TrueValues.inverse();

          Result = LVILatticeVal::getRange(TrueValues);
          return true;
        }
      }
    }
  }

  // If the edge was formed by a switch on the value, then we may know exactly
  // what it is.
  if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) {
    if (SI->getCondition() != Val)
      return false;

    bool DefaultCase = SI->getDefaultDest() == BBTo;
    unsigned BitWidth = Val->getType()->getIntegerBitWidth();
    ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/);

    for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
         i != e; ++i) {
      ConstantRange EdgeVal(i.getCaseValue()->getValue());
      if (DefaultCase) {
        // It is possible that the default destination is the destination of
        // some cases. There is no need to perform difference for those cases.
        if (i.getCaseSuccessor() != BBTo)
          EdgesVals = EdgesVals.difference(EdgeVal);
      } else if (i.getCaseSuccessor() == BBTo)
        EdgesVals = EdgesVals.unionWith(EdgeVal);
    }
    Result = LVILatticeVal::getRange(EdgesVals);
    return true;
  }
  return false;
}

/// IsTrivialUnswitchCondition - Check to see if this unswitch condition is
/// trivial: that is, that the condition controls whether or not the loop does
/// anything at all.  If this is a trivial condition, unswitching produces no
/// code duplications (equivalently, it produces a simpler loop and a new empty
/// loop, which gets deleted).
///
/// If this is a trivial condition, return true, otherwise return false.  When
/// returning true, this sets Cond and Val to the condition that controls the
/// trivial condition: when Cond dynamically equals Val, the loop is known to
/// exit.  Finally, this sets LoopExit to the BB that the loop exits to when
/// Cond == Val.
///
bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val,
                                       BasicBlock **LoopExit) {
  BasicBlock *Header = currentLoop->getHeader();
  TerminatorInst *HeaderTerm = Header->getTerminator();
  LLVMContext &Context = Header->getContext();

  BasicBlock *LoopExitBB = 0;
  if (BranchInst *BI = dyn_cast<BranchInst>(HeaderTerm)) {
    // If the header block doesn't end with a conditional branch on Cond, we
    // can't handle it.
    if (!BI->isConditional() || BI->getCondition() != Cond)
      return false;

    // Check to see if a successor of the branch is guaranteed to
    // exit through a unique exit block without having any
    // side-effects.  If so, determine the value of Cond that causes it to do
    // this.
    if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
                                             BI->getSuccessor(0)))) {
      if (Val) *Val = ConstantInt::getTrue(Context);
    } else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop,
                                                    BI->getSuccessor(1)))) {
      if (Val) *Val = ConstantInt::getFalse(Context);
    }
  } else if (SwitchInst *SI = dyn_cast<SwitchInst>(HeaderTerm)) {
    // If this isn't a switch on Cond, we can't handle it.
    if (SI->getCondition() != Cond) return false;

    // Check to see if a successor of the switch is guaranteed to go to the
    // latch block or exit through a one exit block without having any
    // side-effects.  If so, determine the value of Cond that causes it to do
    // this.
    // Note that we can't trivially unswitch on the default case or
    // on already unswitched cases.
    for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
         i != e; ++i) {
      BasicBlock* LoopExitCandidate;
      if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop,
                                               i.getCaseSuccessor()))) {
        // Okay, we found a trivial case, remember the value that is trivial.
        ConstantInt* CaseVal = i.getCaseValue();

        // Check that it was not unswitched before, since already unswitched
        // trivial vals are looks trivial too.
        if (BranchesInfo.isUnswitched(SI, CaseVal))
          continue;
        LoopExitBB = LoopExitCandidate;
        if (Val) *Val = CaseVal;
        break;
      }
    }
  }

  // If we didn't find a single unique LoopExit block, or if the loop exit block
  // contains phi nodes, this isn't trivial.
  if (!LoopExitBB || isa<PHINode>(LoopExitBB->begin()))
    return false;   // Can't handle this.

  if (LoopExit) *LoopExit = LoopExitBB;

  // We already know that nothing uses any scalar values defined inside of this
  // loop.  As such, we just have to check to see if this loop will execute any
  // side-effecting instructions (e.g. stores, calls, volatile loads) in the
  // part of the loop that the code *would* execute.  We already checked the
  // tail, check the header now.
  for (BasicBlock::iterator I = Header->begin(), E = Header->end(); I != E; ++I)
    if (I->mayHaveSideEffects())
      return false;
  return true;
}

// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT have
// that value.  Rewrite any uses of LIC or of properties correlated to it.
void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
                                                        Constant *Val,
                                                        bool IsEqual) {
  assert(!isa<Constant>(LIC) && "Why are we unswitching on a constant?");

  // FIXME: Support correlated properties, like:
  //  for (...)
  //    if (li1 < li2)
  //      ...
  //    if (li1 > li2)
  //      ...

  // FOLD boolean conditions (X|LIC), (X&LIC).  Fold conditional branches,
  // selects, switches.
  std::vector<Instruction*> Worklist;
  LLVMContext &Context = Val->getContext();


  // If we know that LIC == Val, or that LIC == NotVal, just replace uses of LIC
  // in the loop with the appropriate one directly.
  if (IsEqual || (isa<ConstantInt>(Val) &&
      Val->getType()->isIntegerTy(1))) {
    Value *Replacement;
    if (IsEqual)
      Replacement = Val;
    else
      Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()),
                                     !cast<ConstantInt>(Val)->getZExtValue());

    for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end();
         UI != E; ++UI) {
      Instruction *U = dyn_cast<Instruction>(*UI);
      if (!U || !L->contains(U))
        continue;
      Worklist.push_back(U);
    }

    for (std::vector<Instruction*>::iterator UI = Worklist.begin();
         UI != Worklist.end(); ++UI)
      (*UI)->replaceUsesOfWith(LIC, Replacement);

    SimplifyCode(Worklist, L);
    return;
  }

  // Otherwise, we don't know the precise value of LIC, but we do know that it
  // is certainly NOT "Val".  As such, simplify any uses in the loop that we
  // can.  This case occurs when we unswitch switch statements.
  for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end();
       UI != E; ++UI) {
    Instruction *U = dyn_cast<Instruction>(*UI);
    if (!U || !L->contains(U))
      continue;

    Worklist.push_back(U);

    // TODO: We could do other simplifications, for example, turning
    // 'icmp eq LIC, Val' -> false.

    // If we know that LIC is not Val, use this info to simplify code.
    SwitchInst *SI = dyn_cast<SwitchInst>(U);
    if (SI == 0 || !isa<ConstantInt>(Val)) continue;

    SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
    // Default case is live for multiple values.
    if (DeadCase == SI->case_default()) continue;

    // Found a dead case value.  Don't remove PHI nodes in the
    // successor if they become single-entry, those PHI nodes may
    // be in the Users list.

    BasicBlock *Switch = SI->getParent();
    BasicBlock *SISucc = DeadCase.getCaseSuccessor();
    BasicBlock *Latch = L->getLoopLatch();

    BranchesInfo.setUnswitched(SI, Val);

    if (!SI->findCaseDest(SISucc)) continue;  // Edge is critical.
    // If the DeadCase successor dominates the loop latch, then the
    // transformation isn't safe since it will delete the sole predecessor edge
    // to the latch.
    if (Latch && DT->dominates(SISucc, Latch))
      continue;

    // FIXME: This is a hack.  We need to keep the successor around
    // and hooked up so as to preserve the loop structure, because
    // trying to update it is complicated.  So instead we preserve the
    // loop structure and put the block on a dead code path.
    SplitEdge(Switch, SISucc, this);
    // Compute the successors instead of relying on the return value
    // of SplitEdge, since it may have split the switch successor
    // after PHI nodes.
    BasicBlock *NewSISucc = DeadCase.getCaseSuccessor();
    BasicBlock *OldSISucc = *succ_begin(NewSISucc);
    // Create an "unreachable" destination.
    BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
                                           Switch->getParent(),
//.........这里部分代码省略.........

//.........这里部分代码省略.........
      
  bool changed = false;
  
  ConstantInt* ConstCondition = dyn_cast_or_null<ConstantInt>(getConstReplacement(Condition));
  if(!ConstCondition) {

    if(Condition.t == SHADOWVAL_INST || Condition.t == SHADOWVAL_ARG) {

      // Switch statements can operate on a ptrtoint operand, of which only ptrtoint(null) is useful:
      if(ImprovedValSetSingle* IVS = dyn_cast_or_null<ImprovedValSetSingle>(getIVSRef(Condition))) {
	
	if(IVS->onlyContainsNulls()) {
	  
	  ConstCondition = cast<ConstantInt>(Constant::getNullValue(SI->invar->I->getOperand(0)->getType()));
	  
	}

      }

    }

  }

  if(!ConstCondition) {
    
    std::pair<ValSetType, ImprovedVal> PathVal;

    if(tryGetPathValue(Condition, SI->parent, PathVal))
      ConstCondition = dyn_cast_val<ConstantInt>(PathVal.second.V);

  }

  TerminatorInst* TI = cast_inst<TerminatorInst>(SI);
  const unsigned NumSucc = TI->getNumSuccessors();

  if(ConstCondition) {

    BasicBlock* takenTarget = 0;

    if(BranchInst* BI = dyn_cast_inst<BranchInst>(SI)) {
      // This ought to be a boolean.
      if(ConstCondition->isZero())
	takenTarget = BI->getSuccessor(1);
      else
	takenTarget = BI->getSuccessor(0);
    }
    else {
      SwitchInst* SwI = cast_inst<SwitchInst>(SI);
      SwitchInst::CaseIt targetidx = SwI->findCaseValue(ConstCondition);
      takenTarget = targetidx.getCaseSuccessor();
    }
    if(takenTarget) {
      // We know where the instruction is going -- remove this block as a predecessor for its other targets.
      LPDEBUG("Branch or switch instruction given known target: " << takenTarget->getName() << "\n");

      return setEdgeAlive(TI, SI->parent, takenTarget);

    }
    
    // Else fall through to set all alive.

  }

  SwitchInst* Switch;
  ImprovedValSetSingle* IVS;

  if((Switch = dyn_cast_inst<SwitchInst>(SI)) && 
     (IVS = dyn_cast<ImprovedValSetSingle>(getIVSRef(Condition))) && 
     IVS->SetType == ValSetTypeScalar && 
     !IVS->Values.empty()) {

    // A set of values feeding a switch. Set each corresponding edge alive.

    bool changed = false;

    for (unsigned i = 0, ilim = IVS->Values.size(); i != ilim; ++i) {
      
      SwitchInst::CaseIt targetit = Switch->findCaseValue(cast<ConstantInt>(getConstReplacement(IVS->Values[i].V)));
      BasicBlock* target = targetit.getCaseSuccessor();
      changed |= setEdgeAlive(TI, SI->parent, target);

    }

    return changed;

  }

  // Condition unknown -- set all successors alive.
  for (unsigned I = 0; I != NumSucc; ++I) {
    
    // Mark outgoing edge alive
    if(!SI->parent->succsAlive[I])
      changed = true;
    SI->parent->succsAlive[I] = true;
    
  }

  return changed;

}

//.........这里部分代码省略.........
        // overflow. So clear them now.
      case Instruction::Add:
      case Instruction::Sub:
        if (!(Binop->hasNoUnsignedWrap() && Binop->hasNoSignedWrap()))
          NewInst = getClearUpper(NewInst, Binop->getType(), Binop);
        break;
      case Instruction::Shl:
        if (!Binop->hasNoUnsignedWrap())
          NewInst = getClearUpper(NewInst, Binop->getType(), Binop);
        break;
        // We modified the upper bits ourselves when implementing AShr
      case Instruction::AShr:
        NewInst = getClearUpper(NewInst, Binop->getType(), Binop);
        break;
        // We should not see FP operators here.
        // We don't handle mul/div.
      case Instruction::FAdd:
      case Instruction::FSub:
      case Instruction::Mul:
      case Instruction::FMul:
      case Instruction::UDiv:
      case Instruction::SDiv:
      case Instruction::FDiv:
      case Instruction::URem:
      case Instruction::SRem:
      case Instruction::FRem:
      case Instruction::BinaryOpsEnd:
        errs() << *Inst << "\n";
        llvm_unreachable("Cannot handle binary operator");
        break;
    }

    State.recordConverted(Binop, NewInst);
  } else if (ICmpInst *Cmp = dyn_cast<ICmpInst>(Inst)) {
    Value *Op0, *Op1;
    // For signed compares, operands are sign-extended to their
    // promoted type. For unsigned or equality compares, the comparison
    // is equivalent with the larger type because they are already
    // zero-extended.
    if (Cmp->isSigned()) {
      Op0 = getSignExtend(State.getConverted(Cmp->getOperand(0)),
                          Cmp->getOperand(0),
                          Cmp);
      Op1 = getSignExtend(State.getConverted(Cmp->getOperand(1)),
                          Cmp->getOperand(1),
                          Cmp);
    } else {
      Op0 = State.getConverted(Cmp->getOperand(0));
      Op1 = State.getConverted(Cmp->getOperand(1));
    }
    ICmpInst *NewInst = new ICmpInst(
        Cmp, Cmp->getPredicate(), Op0, Op1, "");
    State.recordConverted(Cmp, NewInst);
  } else if (SelectInst *Select = dyn_cast<SelectInst>(Inst)) {
    SelectInst *NewInst = SelectInst::Create(
        Select->getCondition(),
        State.getConverted(Select->getTrueValue()),
        State.getConverted(Select->getFalseValue()),
        "", Select);
    State.recordConverted(Select, NewInst);
  } else if (PHINode *Phi = dyn_cast<PHINode>(Inst)) {
    PHINode *NewPhi = PHINode::Create(
        getPromotedType(Phi->getType()),
        Phi->getNumIncomingValues(),
        "", Phi);
    for (unsigned I = 0, E = Phi->getNumIncomingValues(); I < E; ++I) {
      NewPhi->addIncoming(State.getConverted(Phi->getIncomingValue(I)),
                          Phi->getIncomingBlock(I));
    }
    State.recordConverted(Phi, NewPhi);
  } else if (SwitchInst *Switch = dyn_cast<SwitchInst>(Inst)) {
    SwitchInst *NewInst = SwitchInst::Create(
        State.getConverted(Switch->getCondition()),
        Switch->getDefaultDest(),
        Switch->getNumCases(),
        Switch);
    for (SwitchInst::CaseIt I = Switch->case_begin(),
             E = Switch->case_end();
         I != E; ++I) {
      // Build a new case from the ranges that map to the successor BB. Each
      // range consists of a high and low value which are typed, so the ranges
      // must be rebuilt and a new case constructed from them.
      IntegersSubset CaseRanges = I.getCaseValueEx();
      IntegersSubsetToBB CaseBuilder;
      for (unsigned RI = 0, RE = CaseRanges.getNumItems(); RI < RE; ++RI) {
        CaseBuilder.add(
            IntItem::fromConstantInt(cast<ConstantInt>(convertConstant(
                CaseRanges.getItem(RI).getLow().toConstantInt()))),
            IntItem::fromConstantInt(cast<ConstantInt>(convertConstant(
                CaseRanges.getItem(RI).getHigh().toConstantInt()))));
      }
      IntegersSubset Case = CaseBuilder.getCase();
      NewInst->addCase(Case, I.getCaseSuccessor());
    }
    Switch->eraseFromParent();
  } else {
    errs() << *Inst<<"\n";
    llvm_unreachable("unhandled instruction");
  }
}