Reapply "[EquivalenceClasses] Replace findValue with contains (NFC)."

This reverts the revert commit 616f447.

It includes updates to remaining users in Polly and Clang, to avoid
failures when building those projects.

Author: fhahn

clang/lib/Analysis/FlowSensitive/SimplifyConstraints.cpp

@@ -64,9 +64,9 @@ projectToLeaders(const llvm::DenseSet<Atom> &Atoms,
 // `LeaderIt`.
 static llvm::SmallVector<Atom>
 atomsInEquivalenceClass(const llvm::EquivalenceClasses<Atom> &EquivalentAtoms,
-                        llvm::EquivalenceClasses<Atom>::iterator LeaderIt) {
+                        const Atom &At) {
   llvm::SmallVector<Atom> Result;
-  for (auto MemberIt = EquivalentAtoms.member_begin(LeaderIt);
+  for (auto MemberIt = EquivalentAtoms.findLeader(At);
        MemberIt != EquivalentAtoms.member_end(); ++MemberIt)
     Result.push_back(*MemberIt);
   return Result;
@@ -159,19 +159,17 @@ void simplifyConstraints(llvm::SetVector<const Formula *> &Constraints,
       if (TrueAtoms.contains(At) || FalseAtoms.contains(At))
         continue;
       llvm::SmallVector<Atom> Atoms =
-          atomsInEquivalenceClass(EquivalentAtoms, It);
+          atomsInEquivalenceClass(EquivalentAtoms, At);
       if (Atoms.size() == 1)
         continue;
       std::sort(Atoms.begin(), Atoms.end());
       Info->EquivalentAtoms.push_back(std::move(Atoms));
     }
     for (Atom At : TrueAtoms)
-      Info->TrueAtoms.append(atomsInEquivalenceClass(
-          EquivalentAtoms, EquivalentAtoms.findValue(At)));
+      Info->TrueAtoms.append(atomsInEquivalenceClass(EquivalentAtoms, At));
     std::sort(Info->TrueAtoms.begin(), Info->TrueAtoms.end());
     for (Atom At : FalseAtoms)
-      Info->FalseAtoms.append(atomsInEquivalenceClass(
-          EquivalentAtoms, EquivalentAtoms.findValue(At)));
+      Info->FalseAtoms.append(atomsInEquivalenceClass(EquivalentAtoms, At));
     std::sort(Info->FalseAtoms.begin(), Info->FalseAtoms.end());
   }
 }

llvm/include/llvm/ADT/EquivalenceClasses.h

@@ -179,10 +179,9 @@ class EquivalenceClasses {
     return member_iterator(nullptr);
   }
 
-  /// findValue - Return an iterator to the specified value.  If it does not
-  /// exist, end() is returned.
-  iterator findValue(const ElemTy &V) const {
-    return TheMapping.find(V);
+  /// Returns true if \p V is contained an equivalence class.
+  bool contains(const ElemTy &V) const {
+    return TheMapping.find(V) != TheMapping.end();
   }
 
   /// getLeaderValue - Return the leader for the specified value that is in the

llvm/lib/Analysis/LoopAccessAnalysis.cpp

@@ -1230,7 +1230,7 @@ bool AccessAnalysis::canCheckPtrAtRT(
                      [this](const Value *Ptr) {
                        MemAccessInfo AccessWrite(const_cast<Value *>(Ptr),
                                                  true);
-                       return DepCands.findValue(AccessWrite) == DepCands.end();
+                       return !DepCands.contains(AccessWrite);
                      })) &&
              "Can only skip updating CanDoRT below, if all entries in AS "
              "are reads or there is at most 1 entry");

polly/lib/Analysis/ScopBuilder.cpp

@@ -1856,8 +1856,7 @@ static void joinOperandTree(EquivalenceClasses<Instruction *> &UnionFind,
         continue;
 
       // Check if OpInst is in the BB and is a modeled instruction.
-      auto OpVal = UnionFind.findValue(OpInst);
-      if (OpVal == UnionFind.end())
+      if (!UnionFind.contains(OpInst))
         continue;
 
       UnionFind.unionSets(Inst, OpInst);