Type: Add TypeManager->TypeList() and use for ListVal()

It turns out that for every ListVal we construct, we also allocate
and construct a new TypeList instance, even though they are all the
same. Pre-create and cache the type instances in a new TypeManager.

The following script runs ~10% faster for me after this change.

    global tbl: table[string] of string;
    global i = 0;
    while ( ++i < 10000000 )
        tbl["a"] = "a";

src/Type.cc

@@ -1981,6 +1981,22 @@ detail::TraversalCode VectorType::Traverse(detail::TraversalCallback* cb) const
 	HANDLE_TC_TYPE_POST(tc);
 	}
 
+TypeManager::TypeManager()
+	{
+	for ( auto i = 0u; i < base_list_types.size(); ++i )
+		{
+		TypeTag tag = static_cast<TypeTag>(i);
+		TypePtr pure_type = tag == TYPE_ANY ? nullptr : base_type(tag);
+		base_list_types[tag] = make_intrusive<zeek::TypeList>(pure_type);
+		}
+	}
+
+const TypeListPtr& TypeManager::TypeList(TypeTag t) const
+	{
+	assert(t >= 0 && t < NUM_TYPES);
+	return base_list_types[t];
+	}
+
 // Returns true if t1 is initialization-compatible with t2 (i.e., if an
 // initializer with type t1 can be used to initialize a value with type t2),
 // false otherwise.  Assumes that t1's tag is different from t2's.  Note

src/Type.h

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include <array>
 #include <list>
 #include <map>
 #include <optional>
@@ -866,6 +867,21 @@ protected:
 	TypePtr yield_type;
 	};
 
+// Holds pre-allocated Type objects.
+class TypeManager
+	{
+public:
+	TypeManager();
+
+	// Get a Typelist instance with the given type tag.
+	const TypeListPtr& TypeList(TypeTag t) const;
+
+private:
+	std::array<TypeListPtr, NUM_TYPES> base_list_types;
+	};
+
+extern TypeManager* type_mgr;
+
 // True if the two types are equivalent.  If is_init is true then the test is
 // done in the context of an initialization. If match_record_field_names is
 // true then for record types the field names have to match, too.

src/Val.cc

@@ -1188,10 +1188,7 @@ ValPtr PatternVal::DoClone(CloneState* state)
 	return state->NewClone(this, make_intrusive<PatternVal>(re));
 	}
 
-ListVal::ListVal(TypeTag t) : Val(make_intrusive<TypeList>(t == TYPE_ANY ? nullptr : base_type(t)))
+ListVal::ListVal(TypeTag t) : Val(type_mgr->TypeList(t)), tag(t) { }
-	{
-	tag = t;
-	}
 
 ListVal::~ListVal() { }
 

src/zeek-setup.cc

@@ -172,6 +172,7 @@ void do_ssl_deinit()
 	} // namespace
 #endif
 
+zeek::TypeManager* zeek::type_mgr = nullptr;
 zeek::ValManager* zeek::val_mgr = nullptr;
 zeek::packet_analysis::Manager* zeek::packet_mgr = nullptr;
 zeek::analyzer::Manager* zeek::analyzer_mgr = nullptr;
@@ -437,6 +438,7 @@ static void terminate_zeek()
 	delete session_mgr;
 	delete fragment_mgr;
 	delete telemetry_mgr;
+	delete type_mgr;
 
 	// free the global scope
 	pop_scope();
@@ -593,6 +595,7 @@ SetupResult setup(int argc, char** argv, Options* zopts)
 
 	run_state::zeek_start_time = util::current_time(true);
 
+	type_mgr = new TypeManager();
 	val_mgr = new ValManager();
 	reporter = new Reporter(options.abort_on_scripting_errors);
 	thread_mgr = new threading::Manager();