[IR] Redesign the case iterator in SwitchInst to actually be an iterator

and to expose a handle to represent the actual case rather than having
the iterator return a reference to itself.

All of this allows the iterator to be used with common STL facilities,
standard algorithms, etc.

Doing this exposed some missing facilities in the iterator facade that
I've fixed and required some work to the actual iterator to fully
support the necessary API.

Differential Revision: https://reviews.llvm.org/D31548

llvm-svn: 300032

23 files changed, 101 insertions, 114 deletions

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 376a22bd987..cd85ef3703f 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -1014,8 +1014,8 @@ bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
   // does not (yet) fire.
   SmallPtrSet<BasicBlock *, 8> SuccessorBlocks;
   SuccessorBlocks.insert(SI.getDefaultDest());
-  for (auto I = SI.case_begin(), E = SI.case_end(); I != E; ++I)
-    SuccessorBlocks.insert(I.getCaseSuccessor());
+  for (auto Case : SI.cases())
+    SuccessorBlocks.insert(Case.getCaseSuccessor());
   // Add cost corresponding to the number of distinct destinations. The first
   // we model as free because of fallthrough.
   Cost += (SuccessorBlocks.size() - 1) * InlineConstants::InstrCost;
@@ -1379,7 +1379,7 @@ bool CallAnalyzer::analyzeCall(CallSite CS) {
       Value *Cond = SI->getCondition();
       if (ConstantInt *SimpleCond =
               dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
-        BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
+        BBWorklist.insert(SI->findCaseValue(SimpleCond)->getCaseSuccessor());
         continue;
       }
     }
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 17e781375e4..ad01f7f2f21 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1430,14 +1430,14 @@ static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
     unsigned BitWidth = Val->getType()->getIntegerBitWidth();
     ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/);
 
-    for (SwitchInst::CaseIt i : SI->cases()) {
-      ConstantRange EdgeVal(i.getCaseValue()->getValue());
+    for (auto Case : SI->cases()) {
+      ConstantRange EdgeVal(Case.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)
+        if (Case.getCaseSuccessor() != BBTo)
           EdgesVals = EdgesVals.difference(EdgeVal);
-      } else if (i.getCaseSuccessor() == BBTo)
+      } else if (Case.getCaseSuccessor() == BBTo)
         EdgesVals = EdgesVals.unionWith(EdgeVal);
     }
     Result = LVILatticeVal::getRange(std::move(EdgesVals));
diff --git a/llvm/lib/Analysis/SparsePropagation.cpp b/llvm/lib/Analysis/SparsePropagation.cpp
index 79dc84e2553..470f4bee1e0 100644
--- a/llvm/lib/Analysis/SparsePropagation.cpp
+++ b/llvm/lib/Analysis/SparsePropagation.cpp
@@ -195,7 +195,7 @@ void SparseSolver::getFeasibleSuccessors(TerminatorInst &TI,
     Succs.assign(TI.getNumSuccessors(), true);
     return;
   }
-  SwitchInst::CaseIt Case = SI.findCaseValue(cast<ConstantInt>(C));
+  SwitchInst::CaseHandle Case = *SI.findCaseValue(cast<ConstantInt>(C));
   Succs[Case.getSuccessorIndex()] = true;
 }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 7b494d4b9dd..043441bac4d 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -2578,7 +2578,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
       pushValue(SI.getCondition(), InstID, Vals);
       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
-      for (SwitchInst::ConstCaseIt Case : SI.cases()) {
+      for (auto Case : SI.cases()) {
         Vals.push_back(VE.getValueID(Case.getCaseValue()));
         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
       }
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index e2bb3780e3e..2bdd189557b 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -5457,7 +5457,7 @@ bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
   auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
   ExtInst->insertBefore(SI);
   SI->setCondition(ExtInst);
-  for (SwitchInst::CaseIt Case : SI->cases()) {
+  for (auto Case : SI->cases()) {
     APInt NarrowConst = Case.getCaseValue()->getValue();
     APInt WideConst = (ExtType == Instruction::ZExt) ?
                       NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
diff --git a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
index 923f6e7147d..e29e9fc2c70 100644
--- a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
+++ b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
@@ -899,10 +899,10 @@ void Interpreter::visitSwitchInst(SwitchInst &I) {
 
   // Check to see if any of the cases match...
   BasicBlock *Dest = nullptr;
-  for (SwitchInst::CaseIt i = I.case_begin(), e = I.case_end(); i != e; ++i) {
-    GenericValue CaseVal = getOperandValue(i.getCaseValue(), SF);
+  for (auto Case : I.cases()) {
+    GenericValue CaseVal = getOperandValue(Case.getCaseValue(), SF);
     if (executeICMP_EQ(CondVal, CaseVal, ElTy).IntVal != 0) {
-      Dest = cast<BasicBlock>(i.getCaseSuccessor());
+      Dest = cast<BasicBlock>(Case.getCaseSuccessor());
       break;
     }
   }
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 50774a395b5..d0b77e7218b 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2897,12 +2897,11 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     Out << ", ";
     writeOperand(SI.getDefaultDest(), true);
     Out << " [";
-    for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
-         i != e; ++i) {
+    for (auto Case : SI.cases()) {
       Out << "\n    ";
-      writeOperand(i.getCaseValue(), true);
+      writeOperand(Case.getCaseValue(), true);
       Out << ", ";
-      writeOperand(i.getCaseSuccessor(), true);
+      writeOperand(Case.getCaseSuccessor(), true);
     }
     Out << "\n  ]";
   } else if (isa<IndirectBrInst>(I)) {
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index d61684b5278..faa5ed078cf 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3659,16 +3659,16 @@ void SwitchInst::addCase(ConstantInt *OnVal, BasicBlock *Dest) {
   // Initialize some new operands.
   assert(OpNo+1 < ReservedSpace && "Growing didn't work!");
   setNumHungOffUseOperands(OpNo+2);
-  CaseIt Case(this, NewCaseIdx);
+  CaseHandle Case(this, NewCaseIdx);
   Case.setValue(OnVal);
   Case.setSuccessor(Dest);
 }
 
 /// removeCase - This method removes the specified case and its successor
 /// from the switch instruction.
-SwitchInst::CaseIt SwitchInst::removeCase(CaseIt i) {
-  unsigned idx = i.getCaseIndex();
-  
+SwitchInst::CaseIt SwitchInst::removeCase(CaseIt I) {
+  unsigned idx = I->getCaseIndex();
+
   assert(2 + idx*2 < getNumOperands() && "Case index out of range!!!");
 
   unsigned NumOps = getNumOperands();
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 952a0e5554c..ab648f884c5 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -185,9 +185,9 @@ static void handleFinalSuspend(IRBuilder<> &Builder, Value *FramePtr,
                                coro::Shape &Shape, SwitchInst *Switch,
                                bool IsDestroy) {
   assert(Shape.HasFinalSuspend);
-  auto FinalCase = --Switch->case_end();
-  BasicBlock *ResumeBB = FinalCase.getCaseSuccessor();
-  Switch->removeCase(FinalCase);
+  auto FinalCaseIt = std::prev(Switch->case_end());
+  BasicBlock *ResumeBB = FinalCaseIt->getCaseSuccessor();
+  Switch->removeCase(FinalCaseIt);
   if (IsDestroy) {
     BasicBlock *OldSwitchBB = Switch->getParent();
     auto *NewSwitchBB = OldSwitchBB->splitBasicBlock(Switch, "Switch");
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 99243b7444a..f8b930f5771 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2254,11 +2254,11 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
   ConstantInt *AddRHS;
   if (match(Cond, m_Add(m_Value(Op0), m_ConstantInt(AddRHS)))) {
     // Change 'switch (X+4) case 1:' into 'switch (X) case -3'.
-    for (SwitchInst::CaseIt CaseIter : SI.cases()) {
-      Constant *NewCase = ConstantExpr::getSub(CaseIter.getCaseValue(), AddRHS);
+    for (auto Case : SI.cases()) {
+      Constant *NewCase = ConstantExpr::getSub(Case.getCaseValue(), AddRHS);
       assert(isa<ConstantInt>(NewCase) &&
              "Result of expression should be constant");
-      CaseIter.setValue(cast<ConstantInt>(NewCase));
+      Case.setValue(cast<ConstantInt>(NewCase));
     }
     SI.setCondition(Op0);
     return &SI;
@@ -2290,9 +2290,9 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
     Value *NewCond = Builder->CreateTrunc(Cond, Ty, "trunc");
     SI.setCondition(NewCond);
 
-    for (SwitchInst::CaseIt CaseIter : SI.cases()) {
-      APInt TruncatedCase = CaseIter.getCaseValue()->getValue().trunc(NewWidth);
-      CaseIter.setValue(ConstantInt::get(SI.getContext(), TruncatedCase));
+    for (auto Case : SI.cases()) {
+      APInt TruncatedCase = Case.getCaseValue()->getValue().trunc(NewWidth);
+      Case.setValue(ConstantInt::get(SI.getContext(), TruncatedCase));
     }
     return &SI;
   }
@@ -3072,17 +3072,7 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB, const DataLayout &DL,
       }
     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
       if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
-        // See if this is an explicit destination.
-        for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
-             i != e; ++i)
-          if (i.getCaseValue() == Cond) {
-            BasicBlock *ReachableBB = i.getCaseSuccessor();
-            Worklist.push_back(ReachableBB);
-            continue;
-          }
-
-        // Otherwise it is the default destination.
-        Worklist.push_back(SI->getDefaultDest());
+        Worklist.push_back(SI->findCaseValue(Cond)->getCaseSuccessor());
         continue;
       }
     }
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 42706cc80c7..ed5ad002f60 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -236,7 +236,7 @@ static bool processSwitch(SwitchInst *SI, LazyValueInfo *LVI) {
   // removing a case doesn't cause trouble for the iteration.
   bool Changed = false;
   for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) {
-    ConstantInt *Case = CI.getCaseValue();
+    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.
@@ -269,7 +269,7 @@ static bool processSwitch(SwitchInst *SI, LazyValueInfo *LVI) {
 
     if (State == LazyValueInfo::False) {
       // This case never fires - remove it.
-      CI.getCaseSuccessor()->removePredecessor(BB);
+      CI->getCaseSuccessor()->removePredecessor(BB);
       CI = SI->removeCase(CI);
       CE = SI->case_end();
 
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 17b0c4c69ac..be696df548d 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1761,11 +1761,11 @@ bool GVN::processInstruction(Instruction *I) {
 
     for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
          i != e; ++i) {
-      BasicBlock *Dst = i.getCaseSuccessor();
+      BasicBlock *Dst = i->getCaseSuccessor();
       // If there is only a single edge, propagate the case value into it.
       if (SwitchEdges.lookup(Dst) == 1) {
         BasicBlockEdge E(Parent, Dst);
-        Changed |= propagateEquality(SwitchCond, i.getCaseValue(), E, true);
+        Changed |= propagateEquality(SwitchCond, i->getCaseValue(), E, true);
       }
     }
     return Changed;
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 4b8b434fce9..08eb95a1a3d 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -1269,7 +1269,7 @@ bool JumpThreadingPass::ProcessThreadableEdges(Value *Cond, BasicBlock *BB,
     else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
       DestBB = BI->getSuccessor(cast<ConstantInt>(Val)->isZero());
     else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
-      DestBB = SI->findCaseValue(cast<ConstantInt>(Val)).getCaseSuccessor();
+      DestBB = SI->findCaseValue(cast<ConstantInt>(Val))->getCaseSuccessor();
     } else {
       assert(isa<IndirectBrInst>(BB->getTerminator())
               && "Unexpected terminator");
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 6e5cee4b487..62aa6ee4806 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -509,7 +509,7 @@ analyzeLoopUnrollCost(const Loop *L, unsigned TripCount, DominatorTree &DT,
             KnownSucc = SI->getSuccessor(0);
           else if (ConstantInt *SimpleCondVal =
                        dyn_cast<ConstantInt>(SimpleCond))
-            KnownSucc = SI->findCaseValue(SimpleCondVal).getCaseSuccessor();
+            KnownSucc = SI->findCaseValue(SimpleCondVal)->getCaseSuccessor();
         }
       }
       if (KnownSucc) {
diff --git a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
index fe4161ac948..a99c9999c61 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -709,9 +709,8 @@ bool LoopUnswitch::processCurrentLoop() {
           // Do not process same value again and again.
           // At this point we have some cases already unswitched and
           // some not yet unswitched. Let's find the first not yet unswitched one.
-          for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
-               i != e; ++i) {
-            Constant *UnswitchValCandidate = i.getCaseValue();
+          for (auto Case : SI->cases()) {
+            Constant *UnswitchValCandidate = Case.getCaseValue();
             if (!BranchesInfo.isUnswitched(SI, UnswitchValCandidate)) {
               UnswitchVal = UnswitchValCandidate;
               break;
@@ -987,7 +986,7 @@ bool LoopUnswitch::TryTrivialLoopUnswitch(bool &Changed) {
       if (!Cond)
         break;
       // Find the target block we are definitely going to.
-      CurrentBB = SI->findCaseValue(Cond).getCaseSuccessor();
+      CurrentBB = SI->findCaseValue(Cond)->getCaseSuccessor();
     } else {
       // We do not understand these terminator instructions.
       break;
@@ -1051,13 +1050,12 @@ bool LoopUnswitch::TryTrivialLoopUnswitch(bool &Changed) {
     // 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) {
+    for (auto Case : SI->cases()) {
       BasicBlock *LoopExitCandidate;
-      if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop,
-                                               i.getCaseSuccessor()))) {
+      if ((LoopExitCandidate =
+               isTrivialLoopExitBlock(currentLoop, Case.getCaseSuccessor()))) {
         // Okay, we found a trivial case, remember the value that is trivial.
-        ConstantInt *CaseVal = i.getCaseValue();
+        ConstantInt *CaseVal = Case.getCaseValue();
 
         // Check that it was not unswitched before, since already unswitched
         // trivial vals are looks trivial too.
@@ -1361,9 +1359,11 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
     // NOTE: if a case value for the switch is unswitched out, we record it
     // after the unswitch finishes. We can not record it here as the switch
     // is not a direct user of the partial LIV.
-    SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
+    SwitchInst::CaseHandle DeadCase =
+        *SI->findCaseValue(cast<ConstantInt>(Val));
     // Default case is live for multiple values.
-    if (DeadCase == SI->case_default()) continue;
+    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
diff --git a/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp b/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
index 52975ef3515..a143b9a3c64 100644
--- a/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
+++ b/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
@@ -67,11 +67,11 @@ static bool handleSwitchExpect(SwitchInst &SI) {
   if (!ExpectedValue)
     return false;
 
-  SwitchInst::CaseIt Case = SI.findCaseValue(ExpectedValue);
+  SwitchInst::CaseHandle Case = *SI.findCaseValue(ExpectedValue);
   unsigned n = SI.getNumCases(); // +1 for default case.
   SmallVector<uint32_t, 16> Weights(n + 1, UnlikelyBranchWeight);
 
-  if (Case == SI.case_default())
+  if (Case == *SI.case_default())
     Weights[0] = LikelyBranchWeight;
   else
     Weights[Case.getCaseIndex() + 1] = LikelyBranchWeight;
diff --git a/llvm/lib/Transforms/Scalar/NewGVN.cpp b/llvm/lib/Transforms/Scalar/NewGVN.cpp
index 0b882a0a5c4..6e58b5f8128 100644
--- a/llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -2054,8 +2054,8 @@ void NewGVN::processOutgoingEdges(TerminatorInst *TI, BasicBlock *B) {
     if (CondEvaluated && isa<ConstantInt>(CondEvaluated)) {
       auto *CondVal = cast<ConstantInt>(CondEvaluated);
       // We should be able to get case value for this.
-      auto CaseVal = SI->findCaseValue(CondVal);
-      if (CaseVal.getCaseSuccessor() == SI->getDefaultDest()) {
+      auto Case = *SI->findCaseValue(CondVal);
+      if (Case.getCaseSuccessor() == SI->getDefaultDest()) {
         // We proved the value is outside of the range of the case.
         // We can't do anything other than mark the default dest as reachable,
         // and go home.
@@ -2063,7 +2063,7 @@ void NewGVN::processOutgoingEdges(TerminatorInst *TI, BasicBlock *B) {
         return;
       }
       // Now get where it goes and mark it reachable.
-      BasicBlock *TargetBlock = CaseVal.getCaseSuccessor();
+      BasicBlock *TargetBlock = Case.getCaseSuccessor();
       updateReachableEdge(B, TargetBlock);
     } else {
       for (unsigned i = 0, e = SI->getNumSuccessors(); i != e; ++i) {
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index f2d9f162892..8908dae2f54 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -604,7 +604,7 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
       return;
     }
 
-    Succs[SI->findCaseValue(CI).getSuccessorIndex()] = true;
+    Succs[SI->findCaseValue(CI)->getSuccessorIndex()] = true;
     return;
   }
 
@@ -683,7 +683,7 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
     if (!CI)
       return !SCValue.isUnknown();
 
-    return SI->findCaseValue(CI).getCaseSuccessor() == To;
+    return SI->findCaseValue(CI)->getCaseSuccessor() == To;
   }
 
   // In case of indirect branch and its address is a blockaddress, we mark
@@ -1554,12 +1554,12 @@ bool SCCPSolver::ResolvedUndefsIn(Function &F) {
       // If the input to SCCP is actually switch on undef, fix the undef to
       // the first constant.
       if (isa<UndefValue>(SI->getCondition())) {
-        SI->setCondition(SI->case_begin().getCaseValue());
-        markEdgeExecutable(&BB, SI->case_begin().getCaseSuccessor());
+        SI->setCondition(SI->case_begin()->getCaseValue());
+        markEdgeExecutable(&BB, SI->case_begin()->getCaseSuccessor());
         return true;
       }
 
-      markForcedConstant(SI->getCondition(), SI->case_begin().getCaseValue());
+      markForcedConstant(SI->getCondition(), SI->case_begin()->getCaseValue());
       return true;
     }
   }
diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 3a78158478c..ae58d6133d9 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -354,7 +354,7 @@ void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
       Cond = dyn_cast_or_null<ConstantInt>(V);
     }
     if (Cond) {     // Constant fold to uncond branch!
-      SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
+      SwitchInst::ConstCaseHandle Case = *SI->findCaseValue(Cond);
       BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
       VMap[OldTI] = BranchInst::Create(Dest, NewBB);
       ToClone.push_back(Dest);
diff --git a/llvm/lib/Transforms/Utils/Evaluator.cpp b/llvm/lib/Transforms/Utils/Evaluator.cpp
index e56fb832bf4..59f176e2f23 100644
--- a/llvm/lib/Transforms/Utils/Evaluator.cpp
+++ b/llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -487,7 +487,7 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
         ConstantInt *Val =
           dyn_cast<ConstantInt>(getVal(SI->getCondition()));
         if (!Val) return false;  // Cannot determine.
-        NextBB = SI->findCaseValue(Val).getCaseSuccessor();
+        NextBB = SI->findCaseValue(Val)->getCaseSuccessor();
       } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) {
         Value *Val = getVal(IBI->getAddress())->stripPointerCasts();
         if (BlockAddress *BA = dyn_cast<BlockAddress>(Val))
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 0448913f9b3..18b29226c2e 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -126,20 +126,20 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
     // If the default is unreachable, ignore it when searching for TheOnlyDest.
     if (isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg()) &&
         SI->getNumCases() > 0) {
-      TheOnlyDest = SI->case_begin().getCaseSuccessor();
+      TheOnlyDest = SI->case_begin()->getCaseSuccessor();
     }
 
     // Figure out which case it goes to.
     for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
       // Found case matching a constant operand?
-      if (i.getCaseValue() == CI) {
-        TheOnlyDest = i.getCaseSuccessor();
+      if (i->getCaseValue() == CI) {
+        TheOnlyDest = i->getCaseSuccessor();
         break;
       }
 
       // Check to see if this branch is going to the same place as the default
       // dest.  If so, eliminate it as an explicit compare.
-      if (i.getCaseSuccessor() == DefaultDest) {
+      if (i->getCaseSuccessor() == DefaultDest) {
         MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
         unsigned NCases = SI->getNumCases();
         // Fold the case metadata into the default if there will be any branches
@@ -153,7 +153,7 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
             Weights.push_back(CI->getValue().getZExtValue());
           }
           // Merge weight of this case to the default weight.
-          unsigned idx = i.getCaseIndex();
+          unsigned idx = i->getCaseIndex();
           Weights[0] += Weights[idx+1];
           // Remove weight for this case.
           std::swap(Weights[idx+1], Weights.back());
@@ -172,7 +172,8 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
       // Otherwise, check to see if the switch only branches to one destination.
       // We do this by reseting "TheOnlyDest" to null when we find two non-equal
       // destinations.
-      if (i.getCaseSuccessor() != TheOnlyDest) TheOnlyDest = nullptr;
+      if (i->getCaseSuccessor() != TheOnlyDest)
+        TheOnlyDest = nullptr;
 
       // Increment this iterator as we haven't removed the case.
       ++i;
@@ -211,7 +212,7 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
     if (SI->getNumCases() == 1) {
       // Otherwise, we can fold this switch into a conditional branch
       // instruction if it has only one non-default destination.
-      SwitchInst::CaseIt FirstCase = SI->case_begin();
+      auto FirstCase = *SI->case_begin();
       Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
           FirstCase.getCaseValue(), "cond");
 
diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index 75cd3bc8b2b..b375d51005d 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -356,10 +356,10 @@ unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
   unsigned numCmps = 0;
 
   // Start with "simple" cases
-  for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
-    Cases.push_back(CaseRange(i.getCaseValue(), i.getCaseValue(),
-                              i.getCaseSuccessor()));
-  
+  for (auto Case : SI->cases())
+    Cases.push_back(CaseRange(Case.getCaseValue(), Case.getCaseValue(),
+                              Case.getCaseSuccessor()));
+
   std::sort(Cases.begin(), Cases.end(), CaseCmp());
 
   // Merge case into clusters
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 085a994c328..127a44df534 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -714,10 +714,9 @@ BasicBlock *SimplifyCFGOpt::GetValueEqualityComparisonCases(
     TerminatorInst *TI, std::vector<ValueEqualityComparisonCase> &Cases) {
   if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
     Cases.reserve(SI->getNumCases());
-    for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e;
-         ++i)
-      Cases.push_back(
-          ValueEqualityComparisonCase(i.getCaseValue(), i.getCaseSuccessor()));
+    for (auto Case : SI->cases())
+      Cases.push_back(ValueEqualityComparisonCase(Case.getCaseValue(),
+                                                  Case.getCaseSuccessor()));
     return SI->getDefaultDest();
   }
 
@@ -850,12 +849,12 @@ bool SimplifyCFGOpt::SimplifyEqualityComparisonWithOnlyPredecessor(
       }
     for (SwitchInst::CaseIt i = SI->case_end(), e = SI->case_begin(); i != e;) {
       --i;
-      if (DeadCases.count(i.getCaseValue())) {
+      if (DeadCases.count(i->getCaseValue())) {
         if (HasWeight) {
-          std::swap(Weights[i.getCaseIndex() + 1], Weights.back());
+          std::swap(Weights[i->getCaseIndex() + 1], Weights.back());
           Weights.pop_back();
         }
-        i.getCaseSuccessor()->removePredecessor(TI->getParent());
+        i->getCaseSuccessor()->removePredecessor(TI->getParent());
         SI->removeCase(i);
       }
     }
@@ -3444,8 +3443,8 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
 
   // Find the relevant condition and destinations.
   Value *Condition = Select->getCondition();
-  BasicBlock *TrueBB = SI->findCaseValue(TrueVal).getCaseSuccessor();
-  BasicBlock *FalseBB = SI->findCaseValue(FalseVal).getCaseSuccessor();
+  BasicBlock *TrueBB = SI->findCaseValue(TrueVal)->getCaseSuccessor();
+  BasicBlock *FalseBB = SI->findCaseValue(FalseVal)->getCaseSuccessor();
 
   // Get weight for TrueBB and FalseBB.
   uint32_t TrueWeight = 0, FalseWeight = 0;
@@ -3455,9 +3454,9 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
     GetBranchWeights(SI, Weights);
     if (Weights.size() == 1 + SI->getNumCases()) {
       TrueWeight =
-          (uint32_t)Weights[SI->findCaseValue(TrueVal).getSuccessorIndex()];
+          (uint32_t)Weights[SI->findCaseValue(TrueVal)->getSuccessorIndex()];
       FalseWeight =
-          (uint32_t)Weights[SI->findCaseValue(FalseVal).getSuccessorIndex()];
+          (uint32_t)Weights[SI->findCaseValue(FalseVal)->getSuccessorIndex()];
     }
   }
 
@@ -4160,7 +4159,7 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
       }
     } else if (auto *SI = dyn_cast<SwitchInst>(TI)) {
       for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
-        if (i.getCaseSuccessor() != BB) {
+        if (i->getCaseSuccessor() != BB) {
           ++i;
           continue;
         }
@@ -4251,18 +4250,18 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
   SmallVector<ConstantInt *, 16> CasesA;
   SmallVector<ConstantInt *, 16> CasesB;
 
-  for (SwitchInst::CaseIt I : SI->cases()) {
-    BasicBlock *Dest = I.getCaseSuccessor();
+  for (auto Case : SI->cases()) {
+    BasicBlock *Dest = Case.getCaseSuccessor();
     if (!DestA)
       DestA = Dest;
     if (Dest == DestA) {
-      CasesA.push_back(I.getCaseValue());
+      CasesA.push_back(Case.getCaseValue());
       continue;
     }
     if (!DestB)
       DestB = Dest;
     if (Dest == DestB) {
-      CasesB.push_back(I.getCaseValue());
+      CasesB.push_back(Case.getCaseValue());
       continue;
     }
     return false; // More than two destinations.
@@ -4412,17 +4411,17 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC,
 
   // Remove dead cases from the switch.
   for (ConstantInt *DeadCase : DeadCases) {
-    SwitchInst::CaseIt Case = SI->findCaseValue(DeadCase);
-    assert(Case != SI->case_default() &&
+    SwitchInst::CaseIt CaseI = SI->findCaseValue(DeadCase);
+    assert(CaseI != SI->case_default() &&
            "Case was not found. Probably mistake in DeadCases forming.");
     if (HasWeight) {
-      std::swap(Weights[Case.getCaseIndex() + 1], Weights.back());
+      std::swap(Weights[CaseI->getCaseIndex() + 1], Weights.back());
       Weights.pop_back();
     }
 
     // Prune unused values from PHI nodes.
-    Case.getCaseSuccessor()->removePredecessor(SI->getParent());
-    SI->removeCase(Case);
+    CaseI->getCaseSuccessor()->removePredecessor(SI->getParent());
+    SI->removeCase(CaseI);
   }
   if (HasWeight && Weights.size() >= 2) {
     SmallVector<uint32_t, 8> MDWeights(Weights.begin(), Weights.end());
@@ -4476,10 +4475,9 @@ static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
   typedef DenseMap<PHINode *, SmallVector<int, 4>> ForwardingNodesMap;
   ForwardingNodesMap ForwardingNodes;
 
-  for (SwitchInst::CaseIt I = SI->case_begin(), E = SI->case_end(); I != E;
-       ++I) {
-    ConstantInt *CaseValue = I.getCaseValue();
-    BasicBlock *CaseDest = I.getCaseSuccessor();
+  for (auto Case : SI->cases()) {
+    ConstantInt *CaseValue = Case.getCaseValue();
+    BasicBlock *CaseDest = Case.getCaseSuccessor();
 
     int PhiIndex;
     PHINode *PHI =
@@ -5214,8 +5212,8 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
   // common destination, as well as the min and max case values.
   assert(SI->case_begin() != SI->case_end());
   SwitchInst::CaseIt CI = SI->case_begin();
-  ConstantInt *MinCaseVal = CI.getCaseValue();
-  ConstantInt *MaxCaseVal = CI.getCaseValue();
+  ConstantInt *MinCaseVal = CI->getCaseValue();
+  ConstantInt *MaxCaseVal = CI->getCaseValue();
 
   BasicBlock *CommonDest = nullptr;
   typedef SmallVector<std::pair<ConstantInt *, Constant *>, 4> ResultListTy;
@@ -5225,7 +5223,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
   SmallVector<PHINode *, 4> PHIs;
 
   for (SwitchInst::CaseIt E = SI->case_end(); CI != E; ++CI) {
-    ConstantInt *CaseVal = CI.getCaseValue();
+    ConstantInt *CaseVal = CI->getCaseValue();
     if (CaseVal->getValue().slt(MinCaseVal->getValue()))
       MinCaseVal = CaseVal;
     if (CaseVal->getValue().sgt(MaxCaseVal->getValue()))
@@ -5234,7 +5232,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
     // Resulting value at phi nodes for this case value.
     typedef SmallVector<std::pair<PHINode *, Constant *>, 4> ResultsTy;
     ResultsTy Results;
-    if (!GetCaseResults(SI, CaseVal, CI.getCaseSuccessor(), &CommonDest,
+    if (!GetCaseResults(SI, CaseVal, CI->getCaseSuccessor(), &CommonDest,
                         Results, DL, TTI))
       return false;
 
@@ -5515,11 +5513,10 @@ static bool ReduceSwitchRange(SwitchInst *SI, IRBuilder<> &Builder,
   auto *Rot = Builder.CreateOr(LShr, Shl);
   SI->replaceUsesOfWith(SI->getCondition(), Rot);
 
-  for (SwitchInst::CaseIt C = SI->case_begin(), E = SI->case_end(); C != E;
-       ++C) {
-    auto *Orig = C.getCaseValue();
+  for (auto Case : SI->cases()) {
+    auto *Orig = Case.getCaseValue();
     auto Sub = Orig->getValue() - APInt(Ty->getBitWidth(), Base);
-    C.setValue(
+    Case.setValue(
         cast<ConstantInt>(ConstantInt::get(Ty, Sub.lshr(ShiftC->getValue()))));
   }
   return true;