Taken into account Duncan's comments for r149481 dated by 2nd Feb 2012:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120130/136146.html

Implemented CaseIterator and it solves almost all described issues: we don't need to mix operand/case/successor indexing anymore. Base iterator class is implemented as a template since it may be initialized either from "const SwitchInst*" or from "SwitchInst*".

ConstCaseIt is just a read-only iterator.
CaseIt is read-write iterator; it allows to change case successor and case value.

Usage of iterator allows totally remove resolveXXXX methods. All indexing convertions done automatically inside the iterator's getters.

Main way of iterator usage looks like this:
SwitchInst *SI = ... // intialize it somehow

for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd(); i != e; ++i) {
  BasicBlock *BB = i.getCaseSuccessor();
  ConstantInt *V = i.getCaseValue();
  // Do something.
}

If you want to convert case number to TerminatorInst successor index, just use getSuccessorIndex iterator's method.
If you want initialize iterator from TerminatorInst successor index, use CaseIt::fromSuccessorIndex(...) method.

There are also related changes in llvm-clients: klee and clang.

llvm-svn: 152297

6 files changed, 62 insertions, 54 deletions

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 04ef7d7110c..93125df1460 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -313,8 +313,8 @@ void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
       Cond = dyn_cast_or_null<ConstantInt>(V);
     }
     if (Cond) {     // Constant fold to uncond branch!
-      unsigned CaseIndex = SI->findCaseValue(Cond);
-      BasicBlock *Dest = SI->getSuccessor(SI->resolveSuccessorIndex(CaseIndex));
+      SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
+      BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
       VMap[OldTI] = BranchInst::Create(Dest, NewBB);
       ToClone.push_back(Dest);
       TerminatorDone = true;
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 429919b79a4..e8c0b80c212 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -617,7 +617,8 @@ emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
     // of the other successors.
     TheSwitch->setCondition(call);
     TheSwitch->setDefaultDest(TheSwitch->getSuccessor(NumExitBlocks));
-    TheSwitch->removeCase(NumExitBlocks-1);  // Remove redundant case
+    // Remove redundant case
+    TheSwitch->removeCase(SwitchInst::CaseIt(TheSwitch, NumExitBlocks-1));
     break;
   }
 }
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 336d8f63ec2..6ea3b935757 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -106,31 +106,32 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions) {
     // 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->getDefaultDest();  // The default dest
+    BasicBlock *TheOnlyDest = SI->getDefaultDest();
     BasicBlock *DefaultDest = TheOnlyDest;
 
     // Figure out which case it goes to.
-    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
+    for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+         i != e; ++i) {
       // Found case matching a constant operand?
-      if (SI->getCaseValue(i) == CI) {
-        TheOnlyDest = SI->getCaseSuccessor(i);
+      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 (SI->getCaseSuccessor(i) == DefaultDest) {
+      if (i.getCaseSuccessor() == DefaultDest) {
         // Remove this entry.
         DefaultDest->removePredecessor(SI->getParent());
         SI->removeCase(i);
-        --i; --e;  // Don't skip an entry...
+        --i; --e;
         continue;
       }
 
       // 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->getCaseSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
+      if (i.getCaseSuccessor() != TheOnlyDest) TheOnlyDest = 0;
     }
 
     if (CI && !TheOnlyDest) {
@@ -167,11 +168,13 @@ 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->caseBegin();
       Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
-                                         SI->getCaseValue(0), "cond");
+          FirstCase.getCaseValue(), "cond");
 
       // Insert the new branch.
-      Builder.CreateCondBr(Cond, SI->getCaseSuccessor(0), SI->getDefaultDest());
+      Builder.CreateCondBr(Cond, FirstCase.getCaseSuccessor(),
+                           SI->getDefaultDest());
 
       // Delete the old switch.
       SI->eraseFromParent();
diff --git a/llvm/lib/Transforms/Utils/LowerExpectIntrinsic.cpp b/llvm/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
index df8d68ec8ba..0e9cdf55b24 100644
--- a/llvm/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
+++ b/llvm/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
@@ -73,16 +73,16 @@ bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
   LLVMContext &Context = CI->getContext();
   Type *Int32Ty = Type::getInt32Ty(Context);
 
-  unsigned caseNo = SI->findCaseValue(ExpectedValue);
+  SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue);
   std::vector<Value *> Vec;
   unsigned n = SI->getNumCases();
   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 ?
+  Vec[1] = ConstantInt::get(Int32Ty, Case == SI->caseDefault() ?
                             LikelyBranchWeight : UnlikelyBranchWeight);
   for (unsigned i = 0; i < n; ++i) {
-    Vec[i + 1 + 1] = ConstantInt::get(Int32Ty, i == caseNo ?
+    Vec[i + 1 + 1] = ConstantInt::get(Int32Ty, i == Case.getCaseIndex() ?
         LikelyBranchWeight : UnlikelyBranchWeight);
   }
 
diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index 424f5647742..84029a58731 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -237,10 +237,10 @@ unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
   unsigned numCmps = 0;
 
   // Start with "simple" cases
-  for (unsigned i = 0; i < SI->getNumCases(); ++i)
-    Cases.push_back(CaseRange(SI->getCaseValue(i),
-                              SI->getCaseValue(i),
-                              SI->getCaseSuccessor(i)));
+  for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd(); i != e; ++i)
+    Cases.push_back(CaseRange(i.getCaseValue(), i.getCaseValue(),
+                              i.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 a9853a4185e..33694e9dc07 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -480,9 +480,9 @@ GetValueEqualityComparisonCases(TerminatorInst *TI,
                                                       BasicBlock*> > &Cases) {
   if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
     Cases.reserve(SI->getNumCases());
-    for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
-      Cases.push_back(std::make_pair(SI->getCaseValue(i),
-                                     SI->getCaseSuccessor(i)));
+    for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd(); i != e; ++i)
+      Cases.push_back(std::make_pair(i.getCaseValue(),
+                                     i.getCaseSuccessor()));
     return SI->getDefaultDest();
   }
 
@@ -605,10 +605,10 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
     DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator()
                  << "Through successor TI: " << *TI);
 
-    for (unsigned i = SI->getNumCases(); i != 0;) {
+    for (SwitchInst::CaseIt i = SI->caseEnd(), e = SI->caseBegin(); i != e;) {
       --i;
-      if (DeadCases.count(SI->getCaseValue(i))) {
-        SI->getCaseSuccessor(i)->removePredecessor(TI->getParent());
+      if (DeadCases.count(i.getCaseValue())) {
+        i.getCaseSuccessor()->removePredecessor(TI->getParent());
         SI->removeCase(i);
       }
     }
@@ -2009,10 +2009,8 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
 
   // Find the relevant condition and destinations.
   Value *Condition = Select->getCondition();
-  unsigned TrueCase = SI->findCaseValue(TrueVal);
-  unsigned FalseCase = SI->findCaseValue(FalseVal);
-  BasicBlock *TrueBB = SI->getSuccessor(SI->resolveSuccessorIndex(TrueCase));
-  BasicBlock *FalseBB = SI->getSuccessor(SI->resolveSuccessorIndex(FalseCase));
+  BasicBlock *TrueBB = SI->findCaseValue(TrueVal).getCaseSuccessor();
+  BasicBlock *FalseBB = SI->findCaseValue(FalseVal).getCaseSuccessor();
 
   // Perform the actual simplification.
   return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB);
@@ -2096,7 +2094,7 @@ static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI,
   // 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) != SwitchInst::ErrorIndex) {
+  if (SI->findCaseValue(Cst) != SI->caseDefault()) {
     Value *V;
     if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
       V = ConstantInt::getFalse(BB->getContext());
@@ -2423,8 +2421,9 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
         }
       }
     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
-      for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
-        if (SI->getCaseSuccessor(i) == BB) {
+      for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+           i != e; ++i)
+        if (i.getCaseSuccessor() == BB) {
           BB->removePredecessor(SI->getParent());
           SI->removeCase(i);
           --i; --e;
@@ -2434,12 +2433,13 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
       // destination and make it the default.
       if (SI->getDefaultDest() == BB) {
         std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity;
-        for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i) {
+        for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+             i != e; ++i) {
           std::pair<unsigned, unsigned> &entry =
-              Popularity[SI->getCaseSuccessor(i)];
+              Popularity[i.getCaseSuccessor()];
           if (entry.first == 0) {
             entry.first = 1;
-            entry.second = i;
+            entry.second = i.getCaseIndex();
           } else {
             entry.first++;
           }
@@ -2470,8 +2470,9 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
             for (unsigned i = 0; i != MaxPop-1; ++i)
               MaxBlock->removePredecessor(SI->getParent());
           
-          for (unsigned i = 0, e = SI->getNumCases(); i != e; ++i)
-            if (SI->getCaseSuccessor(i) == MaxBlock) {
+          for (SwitchInst::CaseIt i = SI->caseBegin(), e = SI->caseEnd();
+               i != e; ++i)
+            if (i.getCaseSuccessor() == MaxBlock) {
               SI->removeCase(i);
               --i; --e;
             }
@@ -2517,11 +2518,13 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
 
   // Make sure all cases point to the same destination and gather the values.
   SmallVector<ConstantInt *, 16> Cases;
-  Cases.push_back(SI->getCaseValue(0));
-  for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) {
-    if (SI->getCaseSuccessor(I-1) != SI->getCaseSuccessor(I))
+  SwitchInst::CaseIt I = SI->caseBegin();
+  Cases.push_back(I.getCaseValue());
+  SwitchInst::CaseIt PrevI = I++;
+  for (SwitchInst::CaseIt E = SI->caseEnd(); I != E; PrevI = I++) {
+    if (PrevI.getCaseSuccessor() != I.getCaseSuccessor())
       return false;
-    Cases.push_back(SI->getCaseValue(I));
+    Cases.push_back(I.getCaseValue());
   }
   assert(Cases.size() == SI->getNumCases() && "Not all cases gathered");
 
@@ -2539,10 +2542,11 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
   if (!Offset->isNullValue())
     Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off");
   Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch");
-  Builder.CreateCondBr(Cmp, SI->getCaseSuccessor(0), SI->getDefaultDest());
+  Builder.CreateCondBr(
+      Cmp, SI->caseBegin().getCaseSuccessor(), SI->getDefaultDest());
 
   // Prune obsolete incoming values off the successor's PHI nodes.
-  for (BasicBlock::iterator BBI = SI->getCaseSuccessor(0)->begin();
+  for (BasicBlock::iterator BBI = SI->caseBegin().getCaseSuccessor()->begin();
        isa<PHINode>(BBI); ++BBI) {
     for (unsigned I = 0, E = SI->getNumCases()-1; I != E; ++I)
       cast<PHINode>(BBI)->removeIncomingValue(SI->getParent());
@@ -2562,22 +2566,22 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI) {
 
   // Gather dead cases.
   SmallVector<ConstantInt*, 8> DeadCases;
-  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));
+  for (SwitchInst::CaseIt I = SI->caseBegin(), E = SI->caseEnd(); I != E; ++I) {
+    if ((I.getCaseValue()->getValue() & KnownZero) != 0 ||
+        (I.getCaseValue()->getValue() & KnownOne) != KnownOne) {
+      DeadCases.push_back(I.getCaseValue());
       DEBUG(dbgs() << "SimplifyCFG: switch case '"
-                   << SI->getCaseValue(I)->getValue() << "' is dead.\n");
+                   << I.getCaseValue() << "' is dead.\n");
     }
   }
 
   // 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 &&
+    SwitchInst::CaseIt Case = SI->findCaseValue(DeadCases[I]);
+    assert(Case != SI->caseDefault() &&
            "Case was not found. Probably mistake in DeadCases forming.");
     // Prune unused values from PHI nodes.
-    SI->getCaseSuccessor(Case)->removePredecessor(SI->getParent());
+    Case.getCaseSuccessor()->removePredecessor(SI->getParent());
     SI->removeCase(Case);
   }
 
@@ -2626,9 +2630,9 @@ static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
   typedef DenseMap<PHINode*, SmallVector<int,4> > ForwardingNodesMap;
   ForwardingNodesMap ForwardingNodes;
 
-  for (unsigned I = 0; I < SI->getNumCases(); ++I) { // 0 is the default case.
-    ConstantInt *CaseValue = SI->getCaseValue(I);
-    BasicBlock *CaseDest = SI->getCaseSuccessor(I);
+  for (SwitchInst::CaseIt I = SI->caseBegin(), E = SI->caseEnd(); I != E; ++I) {
+    ConstantInt *CaseValue = I.getCaseValue();
+    BasicBlock *CaseDest = I.getCaseSuccessor();
 
     int PhiIndex;
     PHINode *PHI = FindPHIForConditionForwarding(CaseValue, CaseDest,