Internals: Use and enforce class final for ~5% performance boost.

src/V3SplitVar.cpp

@@ -232,7 +232,7 @@ struct AstNodeComparator {
     }
 };
 
-class UnpackRef {
+class UnpackRef final {
     // m_nodep is called in this context (AstNodeStmt, AstCell, AstNodeFTask, or AstAlways)
     AstNode* m_contextp;
     AstNode* m_nodep;  // ArraySel, SliceSel, ArrayVarRef (entire value)
@@ -283,7 +283,7 @@ public:
     }
 };
 
-class UnpackRefMap {
+class UnpackRefMap final {
 public:
     typedef std::map<AstVar*, std::set<UnpackRef>, AstNodeComparator> MapType;
     typedef MapType::iterator MapIt;
@@ -384,7 +384,7 @@ public:
 
 typedef std::map<AstNodeModule*, RefsInModule, AstNodeComparator> SplitVarRefsMap;
 
-class SplitUnpackedVarVisitor : public AstNVisitor, public SplitVarImpl {
+class SplitUnpackedVarVisitor final : public AstNVisitor, public SplitVarImpl {
     typedef std::set<AstVar*, AstNodeComparator> VarSet;
     VarSet m_foundTargetVar;
     UnpackRefMap m_refs;
@@ -802,7 +802,7 @@ public:
 //  Split packed variables
 
 // Split variable
-class SplitNewVar {
+class SplitNewVar final {
     int m_lsb;  // LSB in the original bitvector
     int m_bitwidth;
     AstVar* m_varp;  // The LSB of this variable is always 0, not m_lsb
@@ -828,7 +828,7 @@ public:
 };
 
 // One Entry instance for an AstVarRef instance
-class PackedVarRefEntry {
+class PackedVarRefEntry final {
     AstNode* m_nodep;  // Either AstSel or AstVarRef is expected.
     int m_lsb;
     int m_bitwidth;
@@ -859,7 +859,7 @@ public:
 };
 
 // How a variable is used
-class PackedVarRef {
+class PackedVarRef final {
     struct SortByFirst {
         bool operator()(const std::pair<int, bool>& a, const std::pair<int, bool>& b) const {
             if (a.first == b.first) return a.second < b.second;
@@ -956,7 +956,7 @@ public:
     }
 };
 
-class SplitPackedVarVisitor : public AstNVisitor, public SplitVarImpl {
+class SplitPackedVarVisitor final : public AstNVisitor, public SplitVarImpl {
     typedef std::map<AstVar*, PackedVarRef, AstNodeComparator> PackedVarRefMap;
     AstNetlist* m_netp;
     AstNodeModule* m_modp;  // Current module (just for log)