SwitchInst refactoring.
The purpose of refactoring is to hide operand roles from SwitchInst user (programmer). If you want to play with operands directly, probably you will need lower level methods than SwitchInst ones (TerminatorInst or may be User). After this patch we can reorganize SwitchInst operands and successors as we want.

What was done:

1. Changed semantics of index inside the getCaseValue method:
getCaseValue(0) means "get first case", not a condition. Use getCondition() if you want to resolve the condition. I propose don't mix SwitchInst case indexing with low level indexing (TI successors indexing, User's operands indexing), since it may be dangerous.
2. By the same reason findCaseValue(ConstantInt*) returns actual number of case value. 0 means first case, not default. If there is no case with given value, ErrorIndex will returned.
3. Added getCaseSuccessor method. I propose to avoid usage of TerminatorInst::getSuccessor if you want to resolve case successor BB. Use getCaseSuccessor instead, since internal SwitchInst organization of operands/successors is hidden and may be changed in any moment.
4. Added resolveSuccessorIndex and resolveCaseIndex. The main purpose of these methods is to see how case successors are really mapped in TerminatorInst.
4.1 "resolveSuccessorIndex" was created if you need to level down from SwitchInst to TerminatorInst. It returns TerminatorInst's successor index for given case successor.
4.2 "resolveCaseIndex" converts low level successors index to case index that curresponds to the given successor.

Note: There are also related compatability fix patches for dragonegg, klee, llvm-gcc-4.0, llvm-gcc-4.2, safecode, clang.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149481 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 2f963d1..884d883 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2455,7 +2455,8 @@
         ConstantInt *Val =
           dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
         if (!Val) return false;  // Cannot determine.
-        NewBB = SI->getSuccessor(SI->findCaseValue(Val));
+        unsigned ValTISucc = SI->resolveSuccessorIndex(SI->findCaseValue(Val));
+        NewBB = SI->getSuccessor(ValTISucc);
       } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) {
         Value *Val = getVal(Values, IBI->getAddress())->stripPointerCasts();
         if (BlockAddress *BA = dyn_cast<BlockAddress>(Val))
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 64ed817..0294d2a 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1251,13 +1251,13 @@
         // change 'switch (X+4) case 1:' into 'switch (X) case -3'
         unsigned NumCases = SI.getNumCases();
         // Skip the first item since that's the default case.
-        for (unsigned i = 1; i < NumCases; ++i) {
+        for (unsigned i = 0; i < NumCases; ++i) {
           ConstantInt* CaseVal = SI.getCaseValue(i);
           Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
                                                       AddRHS);
           assert(isa<ConstantInt>(NewCaseVal) &&
                  "Result of expression should be constant");
-          SI.setSuccessorValue(i, cast<ConstantInt>(NewCaseVal));
+          SI.setCaseValue(i, cast<ConstantInt>(NewCaseVal));
         }
         SI.setCondition(I->getOperand(0));
         Worklist.Add(I);
@@ -1877,15 +1877,15 @@
     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
       if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
         // See if this is an explicit destination.
-        for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
+        for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
           if (SI->getCaseValue(i) == Cond) {
-            BasicBlock *ReachableBB = SI->getSuccessor(i);
+            BasicBlock *ReachableBB = SI->getCaseSuccessor(i);
             Worklist.push_back(ReachableBB);
             continue;
           }
         
         // Otherwise it is the default destination.
-        Worklist.push_back(SI->getSuccessor(0));
+        Worklist.push_back(SI->getDefaultDest());
         continue;
       }
     }
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index d39ef3d..bdcbfb0 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -2085,8 +2085,8 @@
     Value *SwitchCond = SI->getCondition();
     BasicBlock *Parent = SI->getParent();
     bool Changed = false;
-    for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) {
-      BasicBlock *Dst = SI->getSuccessor(i);
+    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
+      BasicBlock *Dst = SI->getCaseSuccessor(i);
       if (isOnlyReachableViaThisEdge(Parent, Dst, DT))
         Changed |= propagateEquality(SwitchCond, SI->getCaseValue(i), Dst);
     }
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index c78db3f..fa25a8f 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -1086,9 +1086,10 @@
       DestBB = 0;
     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->getSuccessor(SI->findCaseValue(cast<ConstantInt>(Val)));
-    else {
+    else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
+      unsigned ValCase = SI->findCaseValue(cast<ConstantInt>(Val));
+      DestBB = SI->getSuccessor(SI->resolveSuccessorIndex(ValCase));
+    } else {
       assert(isa<IndirectBrInst>(BB->getTerminator())
               && "Unexpected terminator");
       DestBB = cast<BlockAddress>(Val)->getBasicBlock();
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 678652d..2c75f63 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -436,7 +436,7 @@
       Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), 
                                              currentLoop, Changed);
       unsigned NumCases = SI->getNumCases(); 
-      if (LoopCond && NumCases > 1) {
+      if (LoopCond && NumCases) {
         // Find a value to unswitch on:
         // FIXME: this should chose the most expensive case!
         // FIXME: scan for a case with a non-critical edge?
@@ -445,7 +445,7 @@
         // 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 (unsigned i = 1; i < NumCases; ++i) {
+        for (unsigned i = 0; i < NumCases; ++i) {
           Constant* UnswitchValCandidate = SI->getCaseValue(i);
           if (!BranchesInfo.isUnswitched(SI, UnswitchValCandidate)) {
             UnswitchVal = UnswitchValCandidate;
@@ -574,10 +574,10 @@
     // this. 
     // Note that we can't trivially unswitch on the default case or
     // on already unswitched cases.
-    for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
+    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
       BasicBlock* LoopExitCandidate;
       if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop, 
-                                               SI->getSuccessor(i)))) {
+                                               SI->getCaseSuccessor(i)))) {
         // Okay, we found a trivial case, remember the value that is trivial.
         ConstantInt* CaseVal = SI->getCaseValue(i);
 
@@ -1118,14 +1118,15 @@
     if (SI == 0 || !isa<ConstantInt>(Val)) continue;
     
     unsigned DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
-    if (DeadCase == 0) continue;  // Default case is live for multiple values.
+    // Default case is live for multiple values.
+    if (DeadCase == SwitchInst::ErrorIndex) 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 = SI->getSuccessor(DeadCase);
+    BasicBlock *SISucc = SI->getCaseSuccessor(DeadCase);
     BasicBlock *Latch = L->getLoopLatch();
     
     BranchesInfo.setUnswitched(SI, Val);
@@ -1145,7 +1146,7 @@
     // 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 = SI->getSuccessor(DeadCase);
+    BasicBlock *NewSISucc = SI->getCaseSuccessor(DeadCase);
     BasicBlock *OldSISucc = *succ_begin(NewSISucc);
     // Create an "unreachable" destination.
     BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 1f8f452..4274b50 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -550,7 +550,7 @@
   }
 
   if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
-    if (TI.getNumSuccessors() < 2) {
+    if (!SI->getNumCases()) {
       Succs[0] = true;
       return;
     }
@@ -564,7 +564,7 @@
       return;
     }
 
-    Succs[SI->findCaseValue(CI)] = true;
+    Succs[SI->resolveSuccessorIndex(SI->findCaseValue(CI))] = true;
     return;
   }
 
@@ -614,7 +614,7 @@
     return true;
 
   if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
-    if (SI->getNumSuccessors() < 2)
+    if (SI->getNumCases() < 1)
       return true;
 
     LatticeVal SCValue = getValueState(SI->getCondition());
@@ -624,9 +624,9 @@
       return !SCValue.isUndefined();
 
     // Make sure to skip the "default value" which isn't a value
-    for (unsigned i = 1, E = SI->getNumSuccessors(); i != E; ++i)
-      if (SI->getSuccessorValue(i) == CI) // Found the taken branch.
-        return SI->getSuccessor(i) == To;
+    for (unsigned i = 0, E = SI->getNumCases(); i != E; ++i)
+      if (SI->getCaseValue(i) == CI) // Found the taken branch.
+        return SI->getCaseSuccessor(i) == To;
 
     // If the constant value is not equal to any of the branches, we must
     // execute default branch.
@@ -1487,7 +1487,7 @@
     }
 
     if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
-      if (SI->getNumSuccessors() < 2)   // no cases
+      if (!SI->getNumCases())
         continue;
       if (!getValueState(SI->getCondition()).isUndefined())
         continue;
@@ -1495,12 +1495,12 @@
       // 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->getCaseValue(1));
-        markEdgeExecutable(BB, TI->getSuccessor(1));
+        SI->setCondition(SI->getCaseValue(0));
+        markEdgeExecutable(BB, SI->getCaseSuccessor(0));
         return true;
       }
 
-      markForcedConstant(SI->getCondition(), SI->getCaseValue(1));
+      markForcedConstant(SI->getCondition(), SI->getCaseValue(0));
       return true;
     }
   }
diff --git a/lib/Transforms/Utils/CloneFunction.cpp b/lib/Transforms/Utils/CloneFunction.cpp
index 6ddbed2..f817a21 100644
--- a/lib/Transforms/Utils/CloneFunction.cpp
+++ b/lib/Transforms/Utils/CloneFunction.cpp
@@ -314,7 +314,8 @@
       Cond = dyn_cast_or_null<ConstantInt>(V);
     }
     if (Cond) {     // Constant fold to uncond branch!
-      BasicBlock *Dest = SI->getSuccessor(SI->findCaseValue(Cond));
+      unsigned CaseIndex = SI->findCaseValue(Cond);
+      BasicBlock *Dest = SI->getSuccessor(SI->resolveSuccessorIndex(CaseIndex));
       VMap[OldTI] = BranchInst::Create(Dest, NewBB);
       ToClone.push_back(Dest);
       TerminatorDone = true;
diff --git a/lib/Transforms/Utils/CodeExtractor.cpp b/lib/Transforms/Utils/CodeExtractor.cpp
index 5f47ebb..429919b 100644
--- a/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/lib/Transforms/Utils/CodeExtractor.cpp
@@ -615,9 +615,9 @@
   default:
     // Otherwise, make the default destination of the switch instruction be one
     // of the other successors.
-    TheSwitch->setOperand(0, call);
-    TheSwitch->setSuccessor(0, TheSwitch->getSuccessor(NumExitBlocks));
-    TheSwitch->removeCase(NumExitBlocks);  // Remove redundant case
+    TheSwitch->setCondition(call);
+    TheSwitch->setDefaultDest(TheSwitch->getSuccessor(NumExitBlocks));
+    TheSwitch->removeCase(NumExitBlocks-1);  // Remove redundant case
     break;
   }
 }
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 4dd93cf..336d8f6 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -106,22 +106,20 @@
     // If we are switching on a constant, we can convert the switch into a
     // single branch instruction!
     ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
-    BasicBlock *TheOnlyDest = SI->getSuccessor(0);  // The default dest
+    BasicBlock *TheOnlyDest = SI->getDefaultDest();  // The default dest
     BasicBlock *DefaultDest = TheOnlyDest;
-    assert(TheOnlyDest == SI->getDefaultDest() &&
-           "Default destination is not successor #0?");
 
     // Figure out which case it goes to.
-    for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
+    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
       // Found case matching a constant operand?
-      if (SI->getSuccessorValue(i) == CI) {
-        TheOnlyDest = SI->getSuccessor(i);
+      if (SI->getCaseValue(i) == CI) {
+        TheOnlyDest = SI->getCaseSuccessor(i);
         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 (SI->getSuccessor(i) == DefaultDest) {
+      if (SI->getCaseSuccessor(i) == DefaultDest) {
         // Remove this entry.
         DefaultDest->removePredecessor(SI->getParent());
         SI->removeCase(i);
@@ -132,7 +130,7 @@
       // 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 (SI->getSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
+      if (SI->getCaseSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
     }
 
     if (CI && !TheOnlyDest) {
@@ -166,14 +164,14 @@
       return true;
     }
     
-    if (SI->getNumSuccessors() == 2) {
+    if (SI->getNumCases() == 1) {
       // Otherwise, we can fold this switch into a conditional branch
       // instruction if it has only one non-default destination.
       Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
-                                         SI->getSuccessorValue(1), "cond");
+                                         SI->getCaseValue(0), "cond");
 
       // Insert the new branch.
-      Builder.CreateCondBr(Cond, SI->getSuccessor(1), SI->getSuccessor(0));
+      Builder.CreateCondBr(Cond, SI->getCaseSuccessor(0), SI->getDefaultDest());
 
       // Delete the old switch.
       SI->eraseFromParent();
diff --git a/lib/Transforms/Utils/LowerExpectIntrinsic.cpp b/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
index 9fdc06a..df8d68e 100644
--- a/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
+++ b/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
@@ -76,11 +76,14 @@
   unsigned caseNo = SI->findCaseValue(ExpectedValue);
   std::vector<Value *> Vec;
   unsigned n = SI->getNumCases();
-  Vec.resize(n + 1); // +1 for MDString
+  Vec.resize(n + 1 + 1); // +1 for MDString and +1 for default case
 
   Vec[0] = MDString::get(Context, "branch_weights");
+  Vec[1] = ConstantInt::get(Int32Ty, SwitchInst::ErrorIndex == caseNo ?
+                            LikelyBranchWeight : UnlikelyBranchWeight);
   for (unsigned i = 0; i < n; ++i) {
-    Vec[i + 1] = ConstantInt::get(Int32Ty, i == caseNo ? LikelyBranchWeight : UnlikelyBranchWeight);
+    Vec[i + 1 + 1] = ConstantInt::get(Int32Ty, i == caseNo ?
+        LikelyBranchWeight : UnlikelyBranchWeight);
   }
 
   MDNode *WeightsNode = llvm::MDNode::get(Context, Vec);
diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp
index 686178c..424f564 100644
--- a/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/lib/Transforms/Utils/LowerSwitch.cpp
@@ -237,10 +237,10 @@
   unsigned numCmps = 0;
 
   // Start with "simple" cases
-  for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
-    Cases.push_back(CaseRange(SI->getSuccessorValue(i),
-                              SI->getSuccessorValue(i),
-                              SI->getSuccessor(i)));
+  for (unsigned i = 0; i < SI->getNumCases(); ++i)
+    Cases.push_back(CaseRange(SI->getCaseValue(i),
+                              SI->getCaseValue(i),
+                              SI->getCaseSuccessor(i)));
   std::sort(Cases.begin(), Cases.end(), CaseCmp());
 
   // Merge case into clusters
@@ -281,7 +281,7 @@
   BasicBlock* Default = SI->getDefaultDest();
 
   // If there is only the default destination, don't bother with the code below.
-  if (SI->getNumCases() == 1) {
+  if (!SI->getNumCases()) {
     BranchInst::Create(SI->getDefaultDest(), CurBlock);
     CurBlock->getInstList().erase(SI);
     return;
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index d5ae609..a938b99 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -481,8 +481,9 @@
                                                       BasicBlock*> > &Cases) {
   if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
     Cases.reserve(SI->getNumCases());
-    for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
-      Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i)));
+    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
+      Cases.push_back(std::make_pair(SI->getCaseValue(i),
+                                     SI->getCaseSuccessor(i)));
     return SI->getDefaultDest();
   }
 
@@ -605,11 +606,13 @@
     DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
                  << "Through successor TI: " << *TI);
 
-    for (unsigned i = SI->getNumCases()-1; i != 0; --i)
+    for (unsigned i = SI->getNumCases(); i != 0;) {
+      --i;
       if (DeadCases.count(SI->getCaseValue(i))) {
-        SI->getSuccessor(i)->removePredecessor(TI->getParent());
+        SI->getCaseSuccessor(i)->removePredecessor(TI->getParent());
         SI->removeCase(i);
       }
+    }
 
     DEBUG(dbgs() << "Leaving: " << *TI << "\n");
     return true;
@@ -2007,8 +2010,10 @@
 
   // Find the relevant condition and destinations.
   Value *Condition = Select->getCondition();
-  BasicBlock *TrueBB = SI->getSuccessor(SI->findCaseValue(TrueVal));
-  BasicBlock *FalseBB = SI->getSuccessor(SI->findCaseValue(FalseVal));
+  unsigned TrueCase = SI->findCaseValue(TrueVal);
+  unsigned FalseCase = SI->findCaseValue(FalseVal);
+  BasicBlock *TrueBB = SI->getSuccessor(SI->resolveSuccessorIndex(TrueCase));
+  BasicBlock *FalseBB = SI->getSuccessor(SI->resolveSuccessorIndex(FalseCase));
 
   // Perform the actual simplification.
   return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB);
@@ -2092,7 +2097,7 @@
   // Ok, the block is reachable from the default dest.  If the constant we're
   // comparing exists in one of the other edges, then we can constant fold ICI
   // and zap it.
-  if (SI->findCaseValue(Cst) != 0) {
+  if (SI->findCaseValue(Cst) != SwitchInst::ErrorIndex) {
     Value *V;
     if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
       V = ConstantInt::getFalse(BB->getContext());
@@ -2465,8 +2470,8 @@
         }
       }
     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
-      for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
-        if (SI->getSuccessor(i) == BB) {
+      for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
+        if (SI->getCaseSuccessor(i) == BB) {
           BB->removePredecessor(SI->getParent());
           SI->removeCase(i);
           --i; --e;
@@ -2474,11 +2479,11 @@
         }
       // If the default value is unreachable, figure out the most popular
       // destination and make it the default.
-      if (SI->getSuccessor(0) == BB) {
+      if (SI->getDefaultDest() == BB) {
         std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity;
-        for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) {
+        for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
           std::pair<unsigned, unsigned> &entry =
-              Popularity[SI->getSuccessor(i)];
+              Popularity[SI->getCaseSuccessor(i)];
           if (entry.first == 0) {
             entry.first = 1;
             entry.second = i;
@@ -2503,7 +2508,7 @@
         if (MaxBlock) {
           // Make this the new default, allowing us to delete any explicit
           // edges to it.
-          SI->setSuccessor(0, MaxBlock);
+          SI->setDefaultDest(MaxBlock);
           Changed = true;
           
           // If MaxBlock has phinodes in it, remove MaxPop-1 entries from
@@ -2512,8 +2517,8 @@
             for (unsigned i = 0; i != MaxPop-1; ++i)
               MaxBlock->removePredecessor(SI->getParent());
           
-          for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
-            if (SI->getSuccessor(i) == MaxBlock) {
+          for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
+            if (SI->getCaseSuccessor(i) == MaxBlock) {
               SI->removeCase(i);
               --i; --e;
             }
@@ -2555,17 +2560,17 @@
 /// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a
 /// integer range comparison into a sub, an icmp and a branch.
 static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
-  assert(SI->getNumCases() > 2 && "Degenerate switch?");
+  assert(SI->getNumCases() > 1 && "Degenerate switch?");
 
   // Make sure all cases point to the same destination and gather the values.
   SmallVector<ConstantInt *, 16> Cases;
-  Cases.push_back(SI->getCaseValue(1));
-  for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I) {
-    if (SI->getSuccessor(I-1) != SI->getSuccessor(I))
+  Cases.push_back(SI->getCaseValue(0));
+  for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) {
+    if (SI->getCaseSuccessor(I-1) != SI->getCaseSuccessor(I))
       return false;
     Cases.push_back(SI->getCaseValue(I));
   }
-  assert(Cases.size() == SI->getNumCases()-1 && "Not all cases gathered");
+  assert(Cases.size() == SI->getNumCases() && "Not all cases gathered");
 
   // Sort the case values, then check if they form a range we can transform.
   array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate);
@@ -2575,18 +2580,18 @@
   }
 
   Constant *Offset = ConstantExpr::getNeg(Cases.back());
-  Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases()-1);
+  Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases());
 
   Value *Sub = SI->getCondition();
   if (!Offset->isNullValue())
     Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off");
   Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch");
-  Builder.CreateCondBr(Cmp, SI->getSuccessor(1), SI->getDefaultDest());
+  Builder.CreateCondBr(Cmp, SI->getCaseSuccessor(0), SI->getDefaultDest());
 
   // Prune obsolete incoming values off the successor's PHI nodes.
-  for (BasicBlock::iterator BBI = SI->getSuccessor(1)->begin();
+  for (BasicBlock::iterator BBI = SI->getCaseSuccessor(0)->begin();
        isa<PHINode>(BBI); ++BBI) {
-    for (unsigned I = 0, E = SI->getNumCases()-2; I != E; ++I)
+    for (unsigned I = 0, E = SI->getNumCases()-1; I != E; ++I)
       cast<PHINode>(BBI)->removeIncomingValue(SI->getParent());
   }
   SI->eraseFromParent();
@@ -2604,7 +2609,7 @@
 
   // Gather dead cases.
   SmallVector<ConstantInt*, 8> DeadCases;
-  for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) {
+  for (unsigned I = 0, E = SI->getNumCases(); I != E; ++I) {
     if ((SI->getCaseValue(I)->getValue() & KnownZero) != 0 ||
         (SI->getCaseValue(I)->getValue() & KnownOne) != KnownOne) {
       DeadCases.push_back(SI->getCaseValue(I));
@@ -2616,8 +2621,10 @@
   // Remove dead cases from the switch.
   for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) {
     unsigned Case = SI->findCaseValue(DeadCases[I]);
+    assert(Case != SwitchInst::ErrorIndex &&
+           "Case was not found. Probably mistake in DeadCases forming.");
     // Prune unused values from PHI nodes.
-    SI->getSuccessor(Case)->removePredecessor(SI->getParent());
+    SI->getCaseSuccessor(Case)->removePredecessor(SI->getParent());
     SI->removeCase(Case);
   }
 
@@ -2666,9 +2673,9 @@
   typedef DenseMap<PHINode*, SmallVector<int,4> > ForwardingNodesMap;
   ForwardingNodesMap ForwardingNodes;
 
-  for (unsigned I = 1; I < SI->getNumCases(); ++I) { // 0 is the default case.
+  for (unsigned I = 0; I < SI->getNumCases(); ++I) { // 0 is the default case.
     ConstantInt *CaseValue = SI->getCaseValue(I);
-    BasicBlock *CaseDest = SI->getSuccessor(I);
+    BasicBlock *CaseDest = SI->getCaseSuccessor(I);
 
     int PhiIndex;
     PHINode *PHI = FindPHIForConditionForwarding(CaseValue, CaseDest,