diff --git a/include/revng-c/DataLayoutAnalysis/DLATypeSystem.h b/include/revng-c/DataLayoutAnalysis/DLATypeSystem.h
index 8f8fbb651..9f6c8431e 100644
--- a/include/revng-c/DataLayoutAnalysis/DLATypeSystem.h
+++ b/include/revng-c/DataLayoutAnalysis/DLATypeSystem.h
@@ -276,8 +276,8 @@ protected:
   addLink(LayoutTypeSystemNode *Src, LayoutTypeSystemNode *Tgt, TagT &&Tag) {
     if (Src == nullptr or Tgt == nullptr or Src == Tgt)
       return std::make_pair(nullptr, false);
-    revng_assert(Layouts.count(Src));
-    revng_assert(Layouts.count(Tgt));
+    revng_assert(Layouts.contains(Src));
+    revng_assert(Layouts.contains(Tgt));
     auto It = LinkTags.insert(std::forward<TagT>(Tag)).first;
     revng_assert(It != LinkTags.end());
     const TypeLinkTag *T = &*It;
diff --git a/include/revng-c/RestructureCFG/BasicBlockNodeImpl.h b/include/revng-c/RestructureCFG/BasicBlockNodeImpl.h
index 9f92941dc..12b61e766 100644
--- a/include/revng-c/RestructureCFG/BasicBlockNodeImpl.h
+++ b/include/revng-c/RestructureCFG/BasicBlockNodeImpl.h
@@ -195,14 +195,14 @@ inline void handleNeighbors(const BBNodeMap<NodeT> &SubMap,
 
   Neighbors.erase(std::remove_if(Neighbors.begin(),
                                  Neighbors.end(),
-                                 [&SubMap](const auto &NodeWithLabels) {
-                                   return !SubMap.count(NodeWithLabels.first);
+                                 [&SubMap](const auto &LabeledNode) {
+                                   return !SubMap.contains(LabeledNode.first);
                                  }),
                   Neighbors.end());
 
   for (auto &NeighborLabelPair : Neighbors) {
     auto &Neighbor = NeighborLabelPair.first;
-    revng_assert(SubMap.count(Neighbor) != 0);
+    revng_assert(SubMap.contains(Neighbor));
     Neighbor = SubMap.at(Neighbor);
   }
 }
diff --git a/include/revng-c/RestructureCFG/GenerateAst.h b/include/revng-c/RestructureCFG/GenerateAst.h
index 961cab29d..e60598986 100644
--- a/include/revng-c/RestructureCFG/GenerateAst.h
+++ b/include/revng-c/RestructureCFG/GenerateAst.h
@@ -285,9 +285,8 @@ template<class NodeT>
 inline ASTNode *findASTNode(ASTTree &AST,
                             typename RegionCFG<NodeT>::BBNodeMap &TileToNodeMap,
                             BasicBlockNode<NodeT> *Node) {
-  if (TileToNodeMap.count(Node) != 0) {
-    Node = TileToNodeMap.at(Node);
-  }
+  if (auto It = TileToNodeMap.find(Node); It != TileToNodeMap.end())
+    Node = It->second;
 
   return AST.findASTNode(Node);
 }
diff --git a/include/revng-c/RestructureCFG/MetaRegion.h b/include/revng-c/RestructureCFG/MetaRegion.h
index 8fa1df761..42d58ddbc 100644
--- a/include/revng-c/RestructureCFG/MetaRegion.h
+++ b/include/revng-c/RestructureCFG/MetaRegion.h
@@ -98,7 +98,9 @@ public:
 
   bool isSCS() const { return IsSCS; }
 
-  bool containsNode(BasicBlockNodeT *Node) const { return Nodes.count(Node); }
+  bool containsNode(BasicBlockNodeT *Node) const {
+    return Nodes.contains(Node);
+  }
 
   void insertNode(BasicBlockNodeT *NewNode) { Nodes.insert(NewNode); }
 
diff --git a/include/revng-c/RestructureCFG/MetaRegionImpl.h b/include/revng-c/RestructureCFG/MetaRegionImpl.h
index 17771c109..5683ce49f 100644
--- a/include/revng-c/RestructureCFG/MetaRegionImpl.h
+++ b/include/revng-c/RestructureCFG/MetaRegionImpl.h
@@ -27,12 +27,9 @@ void MetaRegion<NodeT>::updateNodes(BasicBlockNodeTSet &Removal,
                                     BasicBlockNodeTVect &OutlinedNodes) {
   // Remove the old SCS nodes
   bool NeedSubstitution = false;
-  for (BasicBlockNodeT *Node : Removal) {
-    if (Nodes.count(Node) != 0) {
-      Nodes.erase(Node);
+  for (BasicBlockNodeT *Node : Removal)
+    if (Nodes.erase(Node))
       NeedSubstitution = true;
-    }
-  }
 
   // Add the collapsed node.
   if (NeedSubstitution) {
diff --git a/include/revng-c/RestructureCFG/RegionCFGTreeImpl.h b/include/revng-c/RestructureCFG/RegionCFGTreeImpl.h
index 0f5e3f762..6943352ec 100644
--- a/include/revng-c/RestructureCFG/RegionCFGTreeImpl.h
+++ b/include/revng-c/RestructureCFG/RegionCFGTreeImpl.h
@@ -388,11 +388,9 @@ RegionCFG<NodeT>::cloneUntilExit(BasicBlockNode<NodeT> *Node,
     // Ensure that we are not processing the sink node.
     revng_assert(CurrentNode != Sink);
 
-    if (AlreadyProcessed.count(CurrentNode) == 0) {
-      AlreadyProcessed.insert(CurrentNode);
-    } else {
+    auto [_, Inserted] = AlreadyProcessed.insert(CurrentNode);
+    if (!Inserted)
       continue;
-    }
 
     // Get the clone of the `CurrentNode`.
     BasicBlockNode<NodeT> *CurrentClone = CloneMap.at(CurrentNode);
@@ -469,7 +467,7 @@ inline void RegionCFG<NodeT>::untangle() {
     llvm::ReversePostOrderTraversal<BasicBlockNode<NodeT> *> RPOT(EntryNode);
 
     for (BasicBlockNode<NodeT> *RPOTBB : RPOT) {
-      if (ConditionalNodesSet.count(RPOTBB) != 0) {
+      if (ConditionalNodesSet.contains(RPOTBB)) {
         ConditionalNodes.push_back(RPOTBB);
       }
     }
@@ -876,7 +874,7 @@ inline void RegionCFG<NodeT>::inflate() {
     RevPostOrderList.push_back(RPOTBB);
     NodesEquivalenceClass[RPOTBB].insert(RPOTBB);
     CloneToOriginalMap[RPOTBB] = RPOTBB;
-    if (ConditionalNodesSet.count(RPOTBB))
+    if (ConditionalNodesSet.contains(RPOTBB))
       ConditionalNodes.push_back(RPOTBB);
   }
   NodesEquivalenceClass[nullptr] = {};
@@ -923,7 +921,7 @@ inline void RegionCFG<NodeT>::inflate() {
 
     int Iteration = 0;
     while (++ListIt != RevPostOrderList.end() and not WorkList.empty()) {
-      if (not WorkList.count(*ListIt))
+      if (not WorkList.contains(*ListIt))
         continue; // Go to the next node in reverse postorder.
 
       // Otherwise this node is in the worklist, and we have to analyze it.
@@ -935,14 +933,14 @@ inline void RegionCFG<NodeT>::inflate() {
       bool AllPredAreVisited = std::all_of(Candidate->predecessors().begin(),
                                            Candidate->predecessors().end(),
                                            [&Visited](auto *Pred) {
-                                             return Visited.count(Pred);
+                                             return Visited.contains(Pred);
                                            });
       WorkList.erase(Candidate);
       Visited.insert(Candidate);
 
       // Comb end flag, which is useful to understand if the dummies we will
       // insert will need to substitute the current postdominator.
-      bool IsCombEnd = CombEndSetIt->second.count(Candidate);
+      bool IsCombEnd = CombEndSetIt->second.contains(Candidate);
 
       if (not IsCombEnd) {
         for (auto &[Successor, EdgeLabel] : Candidate->labeled_successors()) {
@@ -964,7 +962,7 @@ inline void RegionCFG<NodeT>::inflate() {
         revng_log(CombLogger, "Current predecessors are:");
         for (BasicBlockNode<NodeT> *Predecessor : Candidate->predecessors()) {
           revng_log(CombLogger, Predecessor->getNameStr());
-          if (Visited.count(Predecessor))
+          if (Visited.contains(Predecessor))
             NewDummyPredecessors.push_back(Predecessor);
         }
 
@@ -1045,7 +1043,7 @@ inline void RegionCFG<NodeT>::inflate() {
         // they become predecessors of Duplicated
         BasicBlockNodeTVect NotVisitedPredecessors;
         for (BasicBlockNode<NodeT> *Predecessor : Candidate->predecessors())
-          if (not Visited.count(Predecessor))
+          if (not Visited.contains(Predecessor))
             NotVisitedPredecessors.push_back(Predecessor);
 
         for (BasicBlockNode<NodeT> *Predecessor : NotVisitedPredecessors) {
diff --git a/include/revng-c/RestructureCFG/Utils.h b/include/revng-c/RestructureCFG/Utils.h
index 9a9ae0da5..a2a1a5a72 100644
--- a/include/revng-c/RestructureCFG/Utils.h
+++ b/include/revng-c/RestructureCFG/Utils.h
@@ -133,11 +133,7 @@ using BasicBlockNodeTSet = typename BasicBlockNode<NodeT>::BBNodeSet;
 template<class NodeT>
 inline bool alreadyOnStackQuick(BasicBlockNodeTSet<NodeT> &StackSet,
                                 BasicBlockNode<NodeT> *Node) {
-  if (StackSet.count(Node)) {
-    return true;
-  } else {
-    return false;
-  }
+  return StackSet.contains(Node);
 }
 
 template<class NodeT>
@@ -183,7 +179,7 @@ findReachableNodes(BasicBlockNode<NodeT> *Source,
       // computed a filtered post dominator tree, and the `nullptr` passed as
       // argument represents exactly the `VirtualRoot` node which acts as a sink
       // needed for the tree computation.
-      if ((Targets.count(Vertex) != 0)
+      if ((Targets.contains(Vertex))
           or (Target == nullptr && Vertex->successor_size() == 0)) {
         for (auto StackE : Stack) {
           Targets.insert(StackE.first);
@@ -205,7 +201,7 @@ findReachableNodes(BasicBlockNode<NodeT> *Source,
       BasicBlockNode<NodeT> *NextSuccessor = Vertex->getSuccessorI(Index);
       Index++;
       Stack.push_back(std::make_pair(Vertex, Index));
-      if (VisitedEdges.count(std::make_pair(Vertex, NextSuccessor)) == 0
+      if (not VisitedEdges.contains(std::make_pair(Vertex, NextSuccessor))
           and NextSuccessor != Source
           and !alreadyOnStackQuick(StackSet, NextSuccessor)) {
         Stack.push_back(std::make_pair(NextSuccessor, 0));
diff --git a/include/revng-c/Support/IRHelpers.h b/include/revng-c/Support/IRHelpers.h
index 42f72bd15..2982dffab 100644
--- a/include/revng-c/Support/IRHelpers.h
+++ b/include/revng-c/Support/IRHelpers.h
@@ -47,7 +47,7 @@ inline void pushInstructionALAP(llvm::DominatorTree &DT,
   revng_assert(CommonDominator != nullptr);
 
   for (Instruction &I : *CommonDominator) {
-    if (I.isTerminator() or Users.count(&I) != 0) {
+    if (I.isTerminator() or Users.contains(&I)) {
       ToMove->moveBefore(&I);
       return;
     }
diff --git a/include/revng-c/Support/PTMLC.h b/include/revng-c/Support/PTMLC.h
index 0c1e58df2..c417ae3b2 100644
--- a/include/revng-c/Support/PTMLC.h
+++ b/include/revng-c/Support/PTMLC.h
@@ -420,7 +420,7 @@ public:
   }
 
   std::string getLineComment(const llvm::StringRef Str) {
-    revng_check(Str.find("\n") == llvm::StringRef::npos);
+    revng_check(!Str.contains('\n'));
     return ptml::PTMLBuilder::tokenTag("// " + Str.str(), ptml::tokens::Comment)
            + "\n";
   }
diff --git a/lib/Backend/DecompileFunction.cpp b/lib/Backend/DecompileFunction.cpp
index 852b91b48..87c45574a 100644
--- a/lib/Backend/DecompileFunction.cpp
+++ b/lib/Backend/DecompileFunction.cpp
@@ -2012,9 +2012,7 @@ void CCodeGenerator::emitFunction(bool NeedsLocalStateVar,
 
         auto VarTypeIt = TypeMap.find(VarToDeclare);
         if (VarTypeIt != TypeMap.end()) {
-          Out << getNamedCInstance(TypeMap.at(VarToDeclare),
-                                   VarName,
-                                   ThePTMLCBuilder)
+          Out << getNamedCInstance(VarTypeIt->second, VarName, ThePTMLCBuilder)
               << ";\n";
         } else {
           // The only types that are allowed to be missing from the TypeMap
diff --git a/lib/DataLayoutAnalysis/DLATypeSystem.cpp b/lib/DataLayoutAnalysis/DLATypeSystem.cpp
index a2aecdc0f..502730049 100644
--- a/lib/DataLayoutAnalysis/DLATypeSystem.cpp
+++ b/lib/DataLayoutAnalysis/DLATypeSystem.cpp
@@ -478,8 +478,7 @@ bool LayoutTypeSystem::verifyConsistency() const {
       }
 
       // same edge with same tag
-      auto It = P.first->Successors.find({ NodePtr, P.second });
-      if (It == P.first->Successors.end()) {
+      if (!P.first->Successors.contains({ NodePtr, P.second })) {
         if (VerifyDLALog.isEnabled())
           revng_check(false);
         return false;
@@ -493,8 +492,7 @@ bool LayoutTypeSystem::verifyConsistency() const {
       }
 
       // same edge with same tag
-      auto It = P.first->Predecessors.find({ NodePtr, P.second });
-      if (It == P.first->Predecessors.end()) {
+      if (!P.first->Predecessors.contains({ NodePtr, P.second })) {
         if (VerifyDLALog.isEnabled())
           revng_check(false);
         return false;
@@ -560,7 +558,7 @@ bool LayoutTypeSystem::verifyDAG() const {
   std::set<const LayoutTypeSystemNode *> Visited;
   for (const auto &Node : llvm::nodes(this)) {
     revng_assert(Node != nullptr);
-    if (Visited.count(Node))
+    if (Visited.contains(Node))
       continue;
 
     using NonPointerFilterT = EdgeFilteredGraph<LayoutTypeSystemNode *,
@@ -590,7 +588,7 @@ bool LayoutTypeSystem::verifyInstanceDAG() const {
   std::set<const LayoutTypeSystemNode *> Visited;
   for (const auto &Node : llvm::nodes(this)) {
     revng_assert(Node != nullptr);
-    if (Visited.count(Node))
+    if (Visited.contains(Node))
       continue;
 
     using GraphNodeT = const LayoutTypeSystemNode *;
@@ -619,7 +617,7 @@ bool LayoutTypeSystem::verifyPointerDAG() const {
   std::set<const LayoutTypeSystemNode *> Visited;
   for (const auto &Node : llvm::nodes(this)) {
     revng_assert(Node != nullptr);
-    if (Visited.count(Node))
+    if (Visited.contains(Node))
       continue;
 
     using GraphNodeT = const LayoutTypeSystemNode *;
@@ -662,7 +660,7 @@ bool LayoutTypeSystem::verifyInstanceAtOffset0DAG() const {
   std::set<const LayoutTypeSystemNode *> Visited;
   for (const auto &Node : llvm::nodes(this)) {
     revng_assert(Node != nullptr);
-    if (Visited.count(Node))
+    if (Visited.contains(Node))
       continue;
 
     using GraphNodeT = const LayoutTypeSystemNode *;
diff --git a/lib/DataLayoutAnalysis/Middleend/CollapseSCC.cpp b/lib/DataLayoutAnalysis/Middleend/CollapseSCC.cpp
index 17c609959..bbd05d621 100644
--- a/lib/DataLayoutAnalysis/Middleend/CollapseSCC.cpp
+++ b/lib/DataLayoutAnalysis/Middleend/CollapseSCC.cpp
@@ -44,7 +44,7 @@ static bool collapseSCCs(LayoutTypeSystem &TS) {
   for (const auto &Node : llvm::nodes(&TS)) {
     revng_assert(Node != nullptr);
     revng_log(LogVerbose, "## Analyzing SCCs from  " << Node);
-    if (VisitedNodes.count(Node)) {
+    if (VisitedNodes.contains(Node)) {
       revng_log(LogVerbose, "## Was already visited");
       continue;
     }
@@ -53,7 +53,7 @@ static bool collapseSCCs(LayoutTypeSystem &TS) {
     llvm::scc_iterator<NodeT> E = llvm::scc_end(NodeT(Node));
     for (const auto &SCC : llvm::make_range(I, E)) {
       revng_assert(not SCC.empty());
-      if (VisitedNodes.count(SCC[0]))
+      if (VisitedNodes.contains(SCC[0]))
         continue;
       VisitedNodes.insert(SCC.begin(), SCC.end());
 
diff --git a/lib/DataLayoutAnalysis/Middleend/DLAPruneLayoutNodesWithoutLayout.cpp b/lib/DataLayoutAnalysis/Middleend/DLAPruneLayoutNodesWithoutLayout.cpp
index 602250f81..b5ad61484 100644
--- a/lib/DataLayoutAnalysis/Middleend/DLAPruneLayoutNodesWithoutLayout.cpp
+++ b/lib/DataLayoutAnalysis/Middleend/DLAPruneLayoutNodesWithoutLayout.cpp
@@ -51,8 +51,8 @@ bool PruneLayoutNodesWithoutLayout::runOnTypeSystem(LayoutTypeSystem &TS) {
       using GT = GraphTraits<NonPointerFilterT>;
       if (std::any_of(GT::child_begin(N),
                       GT::child_end(N),
-                      [&ToRemove](LTSN *Chld) {
-                        return ToRemove.count(Chld) == 0;
+                      [&ToRemove](LTSN *Child) {
+                        return !ToRemove.contains(Child);
                       })) {
         revng_log(Log, "### ChildHasLayout(N)!");
         continue;
diff --git a/lib/DataLayoutAnalysis/Middleend/DeduplicateFields.cpp b/lib/DataLayoutAnalysis/Middleend/DeduplicateFields.cpp
index cb7847e41..d414c346f 100644
--- a/lib/DataLayoutAnalysis/Middleend/DeduplicateFields.cpp
+++ b/lib/DataLayoutAnalysis/Middleend/DeduplicateFields.cpp
@@ -510,7 +510,7 @@ bool DeduplicateFields::runOnTypeSystem(LayoutTypeSystem &TS) {
                 // need to re-process it, hence we add it to FieldsToCompare,
                 // then set NodeWithFieldsChanged, and remove it from
                 // AnalyzedNodesNotMerged.
-                if (OriginalFields.count(PreservedNode)) {
+                if (OriginalFields.contains(PreservedNode)) {
                   LoggerIndent MaxIndent{ Log };
                   revng_log(Log,
                             "Is an original field. Re-enqueue it for "
diff --git a/lib/DataLayoutAnalysis/Middleend/RemoveBackedges.cpp b/lib/DataLayoutAnalysis/Middleend/RemoveBackedges.cpp
index 671835e09..63a6f972f 100644
--- a/lib/DataLayoutAnalysis/Middleend/RemoveBackedges.cpp
+++ b/lib/DataLayoutAnalysis/Middleend/RemoveBackedges.cpp
@@ -69,7 +69,7 @@ static bool removeBackedgesFromSCC(LayoutTypeSystem &TS) {
     std::set<const LTSN *> Visited;
     for (const auto &Node : llvm::nodes(&TS)) {
       revng_assert(Node != nullptr);
-      if (Visited.count(Node))
+      if (Visited.contains(Node))
         continue;
 
       auto I = llvm::scc_begin(typename SCC::SCCNodeView(Node));
@@ -289,7 +289,7 @@ static bool removeBackedgesFromSCC(LayoutTypeSystem &TS) {
 
           // We haven't pushed, either because NextChild is on the stack, or
           // because it was visited before.
-          if (InStack.count(NextChild)) {
+          if (InStack.contains(NextChild)) {
 
             // If it's on the stack, we're closing a loop.
             // Add all the cross color edges to the edges ToRemove.
@@ -369,7 +369,7 @@ static bool removeBackedgesFromSCC(LayoutTypeSystem &TS) {
     std::set<const LTSN *> Visited;
     for (const auto &Node : llvm::nodes(&TS)) {
       revng_assert(Node != nullptr);
-      if (Visited.count(Node))
+      if (Visited.contains(Node))
         continue;
 
       auto I = llvm::scc_begin(MixedNodeT(Node));
diff --git a/lib/HeadersGeneration/ModelToHeader.cpp b/lib/HeadersGeneration/ModelToHeader.cpp
index 60bf8deb8..2d66e45f7 100644
--- a/lib/HeadersGeneration/ModelToHeader.cpp
+++ b/lib/HeadersGeneration/ModelToHeader.cpp
@@ -73,7 +73,7 @@ static void printTypeDefinitions(const model::Binary &Model,
       for (const auto *Child :
            llvm::children<const TypeDependencyNode *>(Node)) {
         revng_log(Log, "= child " << getNodeLabel(Child));
-        if (Defined.count(Child))
+        if (Defined.contains(Child))
           revng_log(Log, "      DEFINED");
         else
           revng_log(Log, "      NOT DEFINED");
diff --git a/lib/IRCanonicalization/MarkAssignments/MarkAssignments.cpp b/lib/IRCanonicalization/MarkAssignments/MarkAssignments.cpp
index 2031adcec..4eb0bd85a 100644
--- a/lib/IRCanonicalization/MarkAssignments/MarkAssignments.cpp
+++ b/lib/IRCanonicalization/MarkAssignments/MarkAssignments.cpp
@@ -171,7 +171,7 @@ public:
 
   bool isPending(Instruction *Key) const {
     revng_assert(not IsBottom);
-    return TaintedPending.count(Key);
+    return TaintedPending.contains(Key);
   }
 
 public:
diff --git a/lib/PromoteStackPointer/SegregateStackAccessesPass.cpp b/lib/PromoteStackPointer/SegregateStackAccessesPass.cpp
index faebd87fd..17ce5b1d9 100644
--- a/lib/PromoteStackPointer/SegregateStackAccessesPass.cpp
+++ b/lib/PromoteStackPointer/SegregateStackAccessesPass.cpp
@@ -124,7 +124,7 @@ public:
 
   void recordSpan(const Span &Span, Value *BaseAddress) {
     auto Offset = BaseOffset + Span.Offset;
-    revng_assert(Map.count(Offset) == 0);
+    revng_assert(!Map.contains(Offset));
     Map[Offset] = { Span.Size, BaseAddress };
 
     revng_assert(verify());
diff --git a/lib/RestructureCFG/ASTNode.cpp b/lib/RestructureCFG/ASTNode.cpp
index 82dfa70e5..ad7000ffe 100644
--- a/lib/RestructureCFG/ASTNode.cpp
+++ b/lib/RestructureCFG/ASTNode.cpp
@@ -35,12 +35,12 @@ IfNode *ContinueNode::getComputationIfNode() const {
 void IfNode::updateASTNodesPointers(ASTNodeMap &SubstitutionMap) {
   // Update the pointers to the `then` and `else` branches.
   if (hasThen()) {
-    revng_assert(SubstitutionMap.count(Then) != 0);
+    revng_assert(SubstitutionMap.contains(Then));
     Then = SubstitutionMap[Then];
   }
 
   if (hasElse()) {
-    revng_assert(SubstitutionMap.count(Else) != 0);
+    revng_assert(SubstitutionMap.contains(Else));
     Else = SubstitutionMap[Else];
   }
 }
@@ -56,7 +56,7 @@ void SequenceNode::updateASTNodesPointers(ASTNodeMap &SubstitutionMap) {
   // Update all the pointers of the sequence node.
   for (auto NodeIt = NodeVec.begin(); NodeIt != NodeVec.end(); NodeIt++) {
     ASTNode *Node = *NodeIt;
-    revng_assert(SubstitutionMap.count(Node) != 0);
+    revng_assert(SubstitutionMap.contains(Node));
     ASTNode *NewNode = SubstitutionMap[Node];
     *NodeIt = NewNode;
   }
diff --git a/lib/RestructureCFG/ASTTree.cpp b/lib/RestructureCFG/ASTTree.cpp
index 00d7f9e70..a6552866e 100644
--- a/lib/RestructureCFG/ASTTree.cpp
+++ b/lib/RestructureCFG/ASTTree.cpp
@@ -135,7 +135,7 @@ ASTNode *ASTTree::copyASTNodesFrom(ASTTree &OldAST) {
     }
   }
 
-  revng_assert(ASTSubstitutionMap.count(OldAST.getRoot()) != 0);
+  revng_assert(ASTSubstitutionMap.contains(OldAST.getRoot()));
   return ASTSubstitutionMap[OldAST.getRoot()];
 }
 
diff --git a/lib/RestructureCFG/RestructureCFG.cpp b/lib/RestructureCFG/RestructureCFG.cpp
index 9b62a6654..d54e94f64 100644
--- a/lib/RestructureCFG/RestructureCFG.cpp
+++ b/lib/RestructureCFG/RestructureCFG.cpp
@@ -154,7 +154,7 @@ mergeSCSAbnormalRetreating(MetaRegionBBVect &MetaRegions,
     MetaRegionBB &Region = *RegionIt;
 
     // Do not re-analyze blacklisted metaregions.
-    if (BlacklistedMetaregions.count(&Region) == 0) {
+    if (!BlacklistedMetaregions.contains(&Region)) {
 
       // Iterate over all the backedges present in the graph, if the current
       // region contains the source of a backedge, it should contain also the
@@ -286,10 +286,10 @@ static MetaRegionBBPtrVect applyPartialOrder(MetaRegionBBVect &V) {
 
   while (V.size() != Processed.size()) {
     for (auto RegionIt1 = V.begin(); RegionIt1 != V.end(); RegionIt1++) {
-      if (Processed.count(&*RegionIt1) == 0) {
+      if (!Processed.contains(&*RegionIt1)) {
         bool FoundParent = false;
         for (auto RegionIt2 = V.begin(); RegionIt2 != V.end(); RegionIt2++) {
-          if ((RegionIt1 != RegionIt2) and Processed.count(&*RegionIt2) == 0) {
+          if ((RegionIt1 != RegionIt2) and !Processed.contains(&*RegionIt2)) {
             if ((*RegionIt1).getParent() == &*RegionIt2) {
               FoundParent = true;
               break;
@@ -357,7 +357,7 @@ createMetaRegions(const std::set<EdgeDescriptor> &Backedges) {
     do {
       OldNodes = Nodes;
       for (BasicBlockNodeBB *Node : Nodes) {
-        if ((Node != Head) and (AdditionalSCSNodes.count(Node) != 0)) {
+        if ((Node != Head) and (AdditionalSCSNodes.contains(Node))) {
           CombLogger << "Adding additional nodes for region with head: ";
           CombLogger << Head->getNameStr();
           CombLogger << " and relative to node: ";
@@ -818,7 +818,7 @@ bool restructureCFG(Function &F, ASTTree &AST) {
 
         // Handle outgoing edges from SCS nodes.
         for (const auto &[Successor, Labels] : Node->labeled_successors()) {
-          revng_assert(not Backedges.count(EdgeDescriptor(Node, Successor)));
+          revng_assert(not Backedges.contains(EdgeDescriptor(Node, Successor)));
           using ED = EdgeDescriptor;
           auto *NewEdgeSrc = ClonedMap.at(Node);
           auto *NewEdgeTgt = Successor;
@@ -851,7 +851,7 @@ bool restructureCFG(Function &F, ASTTree &AST) {
             }
 
             // Are we moving a backedge with the first iteration outlining?
-            revng_assert(not Backedges.count({ Predecessor, Node }));
+            revng_assert(not Backedges.contains({ Predecessor, Node }));
 
             moveEdgeTarget(EdgeDescriptor(Predecessor, Node),
                            ClonedMap.at(Node));
@@ -969,7 +969,7 @@ bool restructureCFG(Function &F, ASTTree &AST) {
       std::set<EdgeDescriptor> OutEdges = Meta->getOutEdges();
       for (EdgeDescriptor Edge : OutEdges) {
         // We should not be adding new backedges.
-        revng_assert(not Backedges.count(Edge));
+        revng_assert(not Backedges.contains(Edge));
 
         unsigned Idx = SuccessorsIdxMap.at(DeduplicationMap.at(Edge.second));
         auto *IdxSetNode = RootCFG.addSetStateNode(Idx, Edge.second->getName());
diff --git a/lib/Support/IRHelpers.cpp b/lib/Support/IRHelpers.cpp
index bc1d3041b..6da0d9fcd 100644
--- a/lib/Support/IRHelpers.cpp
+++ b/lib/Support/IRHelpers.cpp
@@ -79,7 +79,7 @@ getConstQualifiedExtractedValuesFromInstruction(T *I) {
               if (isCallToTagged(IdentUser, FunctionTags::Parentheses))
                 NextToVisit.insert(IdentUser);
             } else if (auto *PHIUser = llvm::dyn_cast<llvm::PHINode>(User)) {
-              if (not Visited.count(PHIUser))
+              if (not Visited.contains(PHIUser))
                 NextToVisit.insert(PHIUser);
             }
           }
diff --git a/lib/ValueManipulationAnalysis/ContractedGraph.h b/lib/ValueManipulationAnalysis/ContractedGraph.h
index 87c125ad7..7b136a4f1 100644
--- a/lib/ValueManipulationAnalysis/ContractedGraph.h
+++ b/lib/ValueManipulationAnalysis/ContractedGraph.h
@@ -27,7 +27,7 @@ struct ContractedNode {
 
   /// Check if a TypeFlowNode is part of this super node
   bool contains(TypeFlowNode *TFN) const {
-    return InitialNodes.count(TFN) or AdditionalNodes.count(TFN);
+    return InitialNodes.contains(TFN) or AdditionalNodes.contains(TFN);
   }
 };
 
diff --git a/lib/ValueManipulationAnalysis/Mincut.cpp b/lib/ValueManipulationAnalysis/Mincut.cpp
index 0842ec599..689d15fe7 100644
--- a/lib/ValueManipulationAnalysis/Mincut.cpp
+++ b/lib/ValueManipulationAnalysis/Mincut.cpp
@@ -82,7 +82,7 @@ static unsigned calcCost(ContractedGraph &G) {
     NodeColor.Bits.reset(G.Color.firstSetBit());
 
     for (auto *Succ : TFGNode->successors()) {
-      if (Visited.count(Succ))
+      if (Visited.contains(Succ))
         continue;
 
       ColorSet CommonColors;
diff --git a/lib/ValueManipulationAnalysis/TypeFlowGraph.cpp b/lib/ValueManipulationAnalysis/TypeFlowGraph.cpp
index 386029a26..5edc2dc72 100644
--- a/lib/ValueManipulationAnalysis/TypeFlowGraph.cpp
+++ b/lib/ValueManipulationAnalysis/TypeFlowGraph.cpp
@@ -218,7 +218,7 @@ static ColorSet getAcceptedColors(FunctionMetadataCache &Cache,
 
 TypeFlowNode *TypeFlowGraph::addNodeContaining(FunctionMetadataCache &Cache,
                                                const UseOrValue &NC) {
-  revng_assert(not ContentToNodeMap.count(NC));
+  revng_assert(not ContentToNodeMap.contains(NC));
 
   NodeColorProperty InitialColors = { NO_COLOR,
                                       getAcceptedColors(Cache, NC, Model) };
@@ -456,7 +456,7 @@ TypeFlowGraph vma::makeTypeFlowGraphFromFunction(FunctionMetadataCache &Cache,
 
       // Add the Value node
       TypeFlowNode *InstNode;
-      if (TG.ContentToNodeMap.count(&I)) {
+      if (TG.ContentToNodeMap.contains(&I)) {
         // If the instruction has already been added, it must be because of a
         // phi
         revng_assert(any_of(I.users(), IsPhiInstr));
@@ -489,7 +489,7 @@ TypeFlowGraph vma::makeTypeFlowGraphFromFunction(FunctionMetadataCache &Cache,
         // The operand value should have already been visited, unless the
         // instruction is a phi or the operand is a non-instruction
         // (constant, global, arg).
-        if (not TG.ContentToNodeMap.count(Op.get())) {
+        if (not TG.ContentToNodeMap.contains(Op.get())) {
           revng_assert(I.getOpcode() == Instruction::PHI
                        or not isa<Instruction>(Op.get()));
           TG.addNodeContaining(Cache, Op.get());
@@ -525,7 +525,7 @@ void vma::propagateColor(TypeFlowGraph &TG) {
   llvm::df_iterator_default_set<TypeFlowNode *> Visited;
 
   for (auto *Node : TG.nodes()) {
-    bool AlreadyVisited = (Visited.find(Node) != Visited.end());
+    bool AlreadyVisited = Visited.contains(Node);
     // Start from nodes that have only the desired color
     if (AlreadyVisited or not Node->getCandidates().contains(ColorSet(Filter)))
       continue;
@@ -599,7 +599,7 @@ unsigned vma::countCasts(const TypeFlowGraph &TG) {
 
     for (const TypeFlowNode *Succ : TGNode->successors()) {
       // Ignore already visited nodes
-      if (Visited.count(Succ))
+      if (Visited.contains(Succ))
         continue;
 
       auto SuccBits = Succ->getCandidates().Bits;