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

1 files changed, 39 insertions, 35 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index a9853a4..33694e9 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,