[llvm] Replace SmallSet with SmallPtrSet (NFC) (#154068)

This patch replaces SmallSet<T *, N> with SmallPtrSet<T *, N>.  Note
that SmallSet.h "redirects" SmallSet to SmallPtrSet for pointer
element types:

  template <typename PointeeType, unsigned N>
class SmallSet<PointeeType*, N> : public SmallPtrSet<PointeeType*, N>
{};

We only have 140 instances that rely on this "redirection", with the
vast majority of them under llvm/. Since relying on the redirection
doesn't improve readability, this patch replaces SmallSet with
SmallPtrSet for pointer element types.

Author: kazutakahirata

llvm/include/llvm/Analysis/GenericDomTreeUpdaterImpl.h

@@ -383,7 +383,7 @@ void GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::
   // field of all the elements of Edges.
   // I.e., forall elt in Edges, it exists BB in NewBBs
   // such as BB == elt.NewBB.
-  SmallSet<BasicBlockT *, 32> NewBBs;
+  SmallPtrSet<BasicBlockT *, 32> NewBBs;
   for (auto &Edge : Edges)
     NewBBs.insert(Edge.NewBB);
   // For each element in Edges, remember whether or not element

llvm/include/llvm/CodeGen/GlobalISel/LoadStoreOpt.h

@@ -162,7 +162,7 @@ class LLVM_ABI LoadStoreOpt : public MachineFunctionPass {
   DenseMap<unsigned, BitVector> LegalStoreSizes;
   bool IsPreLegalizer = false;
   /// Contains instructions to be erased at the end of a block scan.
-  SmallSet<MachineInstr *, 16> InstsToErase;
+  SmallPtrSet<MachineInstr *, 16> InstsToErase;
 
 public:
   LoadStoreOpt();

llvm/include/llvm/CodeGen/MachinePipeliner.h

@@ -830,7 +830,7 @@ class SMSchedule {
     return ScheduledInstrs[cycle];
   }
 
-  SmallSet<SUnit *, 8>
+  SmallPtrSet<SUnit *, 8>
   computeUnpipelineableNodes(SwingSchedulerDAG *SSD,
                              TargetInstrInfo::PipelinerLoopInfo *PLI);
 

llvm/include/llvm/CodeGen/ScheduleDAG.h

@@ -237,7 +237,7 @@ class TargetRegisterInfo;
   };
 
   /// Keep record of which SUnit are in the same cluster group.
-  typedef SmallSet<SUnit *, 8> ClusterInfo;
+  typedef SmallPtrSet<SUnit *, 8> ClusterInfo;
   constexpr unsigned InvalidClusterId = ~0u;
 
   /// Return whether the input cluster ID's are the same and valid.

llvm/lib/Analysis/CallPrinter.cpp

@@ -70,7 +70,7 @@ class CallGraphDOTInfo {
 
     for (Function &F : M->getFunctionList()) {
       uint64_t localSumFreq = 0;
-      SmallSet<Function *, 16> Callers;
+      SmallPtrSet<Function *, 16> Callers;
       for (User *U : F.users())
         if (isa<CallInst>(U))
           Callers.insert(cast<Instruction>(U)->getFunction());
@@ -99,7 +99,7 @@ class CallGraphDOTInfo {
 
       bool FoundParallelEdge = true;
       while (FoundParallelEdge) {
-        SmallSet<Function *, 16> Visited;
+        SmallPtrSet<Function *, 16> Visited;
         FoundParallelEdge = false;
         for (auto CI = Node->begin(), CE = Node->end(); CI != CE; CI++) {
           if (!(Visited.insert(CI->second->getFunction())).second) {

llvm/lib/Analysis/CaptureTracking.cpp

@@ -405,7 +405,7 @@ void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker,
 
   SmallVector<const Use *, 20> Worklist;
   Worklist.reserve(getDefaultMaxUsesToExploreForCaptureTracking());
-  SmallSet<const Use *, 20> Visited;
+  SmallPtrSet<const Use *, 20> Visited;
 
   auto AddUses = [&](const Value *V) {
     for (const Use &U : V->uses()) {

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -7284,7 +7284,7 @@ ScalarEvolution::getDefiningScopeBound(ArrayRef<const SCEV *> Ops,
                                        bool &Precise) {
   Precise = true;
   // Do a bounded search of the def relation of the requested SCEVs.
-  SmallSet<const SCEV *, 16> Visited;
+  SmallPtrSet<const SCEV *, 16> Visited;
   SmallVector<const SCEV *> Worklist;
   auto pushOp = [&](const SCEV *S) {
     if (!Visited.insert(S).second)

llvm/lib/Analysis/ValueTracking.cpp

@@ -7785,7 +7785,7 @@ bool llvm::mustExecuteUBIfPoisonOnPathTo(Instruction *Root,
 
   // The set of all recursive users we've visited (which are assumed to all be
   // poison because of said visit)
-  SmallSet<const Value *, 16> KnownPoison;
+  SmallPtrSet<const Value *, 16> KnownPoison;
   SmallVector<const Instruction*, 16> Worklist;
   Worklist.push_back(Root);
   while (!Worklist.empty()) {
@@ -8140,8 +8140,8 @@ static bool programUndefinedIfUndefOrPoison(const Value *V,
 
   // Set of instructions that we have proved will yield poison if Inst
   // does.
-  SmallSet<const Value *, 16> YieldsPoison;
-  SmallSet<const BasicBlock *, 4> Visited;
+  SmallPtrSet<const Value *, 16> YieldsPoison;
+  SmallPtrSet<const BasicBlock *, 4> Visited;
 
   YieldsPoison.insert(V);
   Visited.insert(BB);

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -377,7 +377,7 @@ class CodeGenPrepare {
   /// to be optimized again.
   /// Note: Consider building time in this pass, when a BB updated, we need
   /// to insert such BB into FreshBBs for huge function.
-  SmallSet<BasicBlock *, 32> FreshBBs;
+  SmallPtrSet<BasicBlock *, 32> FreshBBs;
 
   void releaseMemory() {
     // Clear per function information.
@@ -1105,7 +1105,7 @@ bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
 
 /// Replace all old uses with new ones, and push the updated BBs into FreshBBs.
 static void replaceAllUsesWith(Value *Old, Value *New,
-                               SmallSet<BasicBlock *, 32> &FreshBBs,
+                               SmallPtrSet<BasicBlock *, 32> &FreshBBs,
                                bool IsHuge) {
   auto *OldI = dyn_cast<Instruction>(Old);
   if (OldI) {
@@ -2135,7 +2135,7 @@ static bool isRemOfLoopIncrementWithLoopInvariant(
 //    Rem = rem == RemAmtLoopInvariant ? 0 : Rem;
 static bool foldURemOfLoopIncrement(Instruction *Rem, const DataLayout *DL,
                                     const LoopInfo *LI,
-                                    SmallSet<BasicBlock *, 32> &FreshBBs,
+                                    SmallPtrSet<BasicBlock *, 32> &FreshBBs,
                                     bool IsHuge) {
   Value *AddOffset, *RemAmt, *AddInst;
   PHINode *LoopIncrPN;
@@ -2534,11 +2534,10 @@ static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
 ///     %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
 ///
 /// If the transform is performed, return true and set ModifiedDT to true.
-static bool despeculateCountZeros(IntrinsicInst *CountZeros,
-                                  LoopInfo &LI,
+static bool despeculateCountZeros(IntrinsicInst *CountZeros, LoopInfo &LI,
                                   const TargetLowering *TLI,
                                   const DataLayout *DL, ModifyDT &ModifiedDT,
-                                  SmallSet<BasicBlock *, 32> &FreshBBs,
+                                  SmallPtrSet<BasicBlock *, 32> &FreshBBs,
                                   bool IsHugeFunc) {
   // If a zero input is undefined, it doesn't make sense to despeculate that.
   if (match(CountZeros->getOperand(1), m_One()))
@@ -4351,7 +4350,7 @@ class AddressingModeCombiner {
                     PhiNodeSet &PhiNodesToMatch) {
     SmallVector<PHIPair, 8> WorkList;
     Matcher.insert({PHI, Candidate});
-    SmallSet<PHINode *, 8> MatchedPHIs;
+    SmallPtrSet<PHINode *, 8> MatchedPHIs;
     MatchedPHIs.insert(PHI);
     WorkList.push_back({PHI, Candidate});
     SmallSet<PHIPair, 8> Visited;
@@ -8635,7 +8634,7 @@ static bool tryUnmergingGEPsAcrossIndirectBr(GetElementPtrInst *GEPI,
 }
 
 static bool optimizeBranch(BranchInst *Branch, const TargetLowering &TLI,
-                           SmallSet<BasicBlock *, 32> &FreshBBs,
+                           SmallPtrSet<BasicBlock *, 32> &FreshBBs,
                            bool IsHugeFunc) {
   // Try and convert
   //  %c = icmp ult %x, 8

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -3517,7 +3517,7 @@ void IRTranslator::finishPendingPhis() {
     Verifier.setCurrentInst(PI);
 #endif // ifndef NDEBUG
 
-    SmallSet<const MachineBasicBlock *, 16> SeenPreds;
+    SmallPtrSet<const MachineBasicBlock *, 16> SeenPreds;
     for (unsigned i = 0; i < PI->getNumIncomingValues(); ++i) {
       auto IRPred = PI->getIncomingBlock(i);
       ArrayRef<Register> ValRegs = getOrCreateVRegs(*PI->getIncomingValue(i));