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

6 files changed, 59 insertions, 50 deletions

diff --git a/lib/Transforms/Utils/CloneFunction.cpp b/lib/Transforms/Utils/CloneFunction.cpp
index 6ddbed2bbe..f817a21cbd 100644
--- a/lib/Transforms/Utils/CloneFunction.cpp
+++ b/lib/Transforms/Utils/CloneFunction.cpp
@@ -314,7 +314,8 @@ void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
       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 5f47ebb782..429919b79a 100644
--- a/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/lib/Transforms/Utils/CodeExtractor.cpp
@@ -615,9 +615,9 @@ emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
   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 4dd93cf2c7..336d8f63ec 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -106,22 +106,20 @@ 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->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 @@ 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 (SI->getSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
+      if (SI->getCaseSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
     }
 
     if (CI && !TheOnlyDest) {
@@ -166,14 +164,14 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions) {
       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 9fdc06a713..df8d68ec8b 100644
--- a/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
+++ b/lib/Transforms/Utils/LowerExpectIntrinsic.cpp
@@ -76,11 +76,14 @@ bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) {
   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 686178ca01..424f564774 100644
--- a/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/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 = 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 @@ void LowerSwitch::processSwitchInst(SwitchInst *SI) {
   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 d5ae609679..a938b99649 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -481,8 +481,9 @@ GetValueEqualityComparisonCases(TerminatorInst *TI,
                                                       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 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
     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 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
 
   // 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 @@ 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) != 0) {
+  if (SI->findCaseValue(Cst) != SwitchInst::ErrorIndex) {
     Value *V;
     if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
       V = ConstantInt::getFalse(BB->getContext());
@@ -2465,8 +2470,8 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
         }
       }
     } 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 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
         }
       // 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 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
         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 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
             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 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
 /// 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 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
   }
 
   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 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI) {
 
   // 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 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI) {
   // 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 @@ static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
   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,