Eliminate "construct on first use" overhead

By depending on initialization order in same compilation unit.
This finishes the circular dependency refactoring.

src/Makefile

@@ -36,7 +36,8 @@ OBJBASE=eclass.o fchar.o filedetails.o fileid.o pdtoken.o pltoken.o debug.o \
   error.o fdep.o fcall.o call.o idquery.o query.o funquery.o \
   logo.o workdb.o obfuscate.o sql.o md5.o os.o pager.o \
   option.o filequery.o mcall.o filemetrics.o funmetrics.o ctconst.o \
-  dirbrowse.o html.o fileutils.o gdisplay.o globobj.o ctag.o timer.o
+  dirbrowse.o html.o fileutils.o gdisplay.o globobj.o ctag.o timer.o \
+  static_init.o
 
 # monitor.o
 
@@ -63,7 +64,7 @@ CFILES=md5.c attr.cpp call.cpp cscout.cpp ctag.cpp ctconst.cpp \
   logo.cpp macro.cpp mcall.cpp metrics.cpp obfuscate.cpp option.cpp os.cpp \
   pager.cpp pdtoken.cpp pltoken.cpp ptoken.cpp query.cpp simple_cpp.cpp \
   sql.cpp stab.cpp tchar.cpp timer.cpp token.cpp tokid.cpp \
-  tokmap.cpp type.cpp workdb.cpp
+  tokmap.cpp type.cpp workdb.cpp static_init.cpp
 
 HEADERS=attr.h call.h compiledre.h cpp.h ctag.h ctconst.h ctoken.h \
   debug.h defs.h dirbrowse.h eclass.h error.h eval.h fcall.h fchar.h fdep.h \

src/filedetails.cpp

@@ -57,27 +57,6 @@
 #include "md5.h"
 #include "os.h"
 
-/*
- * Return the map from file id to file details, controlling the order of its
- * construction through the "Construct on First Use" idiom.
- */
-FI_id_to_details &
-Filedetails::get_i2d()
-{
-	static FI_id_to_details i2d;
-	return i2d;
-}
-
-/*
- * Return a map of files that are exact duplicates, controlling the order
- * of its construction through the "Construct on First Use" idiom.
- */
-FI_hash_to_ids &
-Filedetails::get_identical_files()
-{
-	static FI_hash_to_ids identical_files;
-	return identical_files;
-}
 
 Filedetails::Filedetails(string n, bool r, const FileHash &h) :
 	name(n),
@@ -194,7 +173,7 @@ Filedetails::set_hand_edited()
 void
 Filedetails::clear_all_visited()
 {
-	for (FI_id_to_details::iterator i = get_i2d().begin(); i != get_i2d().end(); i++)
+	for (FI_id_to_details::iterator i = i2d.begin(); i != i2d.end(); i++)
 		i->clear_visited();
 }
 
@@ -248,7 +227,7 @@ unify_file_identifiers(const set<Fileid> &fs)
 void
 Filedetails::unify_identical_files(void)
 {
-	for (FI_hash_to_ids::const_iterator i = get_identical_files().begin(); i != get_identical_files().end(); i++)
+	for (FI_hash_to_ids::const_iterator i = identical_files.begin(); i != identical_files.end(); i++)
 		if (i->second.size() > 1)
 			unify_file_identifiers(i->second);
 }

src/filedetails.h

@@ -40,7 +40,6 @@ using namespace std;
  * in order to keep *values.begin() invariant.
  * This property is used by tokid unique for returning unique tokids
  */
-typedef vector<unsigned char> FileHash;
 typedef map <FileHash, set<Fileid> > FI_hash_to_ids;
 
 // Details we keep for each included file for a given includer
@@ -95,7 +94,7 @@ class Filedetails {
 	vector <bool> processed_lines;;
 	FileIncMap includes;	// Files we include
 	FileIncMap includers;	// Files that include us
-	FileHash hash;		// MD5 hash for the file's contents
+	FileHash hash;			// MD5 hash for the file's contents
 	int ipath_offset;	// Offset in the include file path where this file was found
 	Fileidset runtime_uses;	// Files whose global objects this file uses at runtime
 	Fileidset runtime_used_by;	// Files that use at runtime this file's global objects
@@ -107,11 +106,8 @@ class Filedetails {
 	string contents;	// Original contents, if hand-edited
 	bool visited;                   // For calculating transitive closures
 
-	// Get map from id to file details
-	static FI_id_to_details& get_i2d();
-
-	// Return map of files that are exact duplicates
-	static FI_hash_to_ids& get_identical_files();
+	static FI_id_to_details i2d;	// From id to file details
+	static FI_hash_to_ids identical_files;// Files that are exact duplicates
 public:
 	Attributes attr;		// The projects this file participates in
 	FileMetrics pre_cpp_metrics;	// File's metrics before cpp
@@ -123,16 +119,16 @@ class Filedetails {
 
 	// Return the instance associated with the specified id
 	static Filedetails &get_instance(Fileid fi) {
-		return get_i2d()[fi.get_id()];
+		return i2d[fi.get_id()];
 	}
 
 	static FI_id_to_details::size_type get_i2d_map_size() {
-		return get_i2d().size();
+		return i2d.size();
 	}
 
 	// Add a new instance with the specified ctor values
-	static void add_instance(string n, bool r, const FileHash &hash) {
-		get_i2d().emplace_back(n, r, hash);
+	static void add_instance(string n, bool r, const FileHash &h) {
+		i2d.emplace_back(n, r, h);
 	}
 
 	// Unify identifiers of files that are exact copies
@@ -142,9 +138,8 @@ class Filedetails {
 	static void clear_all_visited();
 
 	// Add fi to the set of files that have the identical hash
-	static void add_identical_file(const FileHash &hash, Fileid fi) {
-		auto &file_set = get_identical_files()[hash];
-		file_set.insert(fi);
+	static void add_identical_file(FileHash hash, Fileid fi) {
+		identical_files[hash].insert(fi);
 	}
 
 	const string& get_name() const { return name; }
@@ -276,7 +271,7 @@ class Filedetails {
 ;
 	// Return the set of files that are the same as this (including this)
 	static const Fileidset & get_identical_files(Fileid id) {
-		return get_identical_files()[get_instance(id).get_filehash()];
+		return identical_files[get_instance(id).get_filehash()];
 	}
 
 	// Return the set of files that we depend on for runtime objects

src/fileid.cpp

@@ -59,29 +59,6 @@
 
 int Fileid::counter;		// To generate ids
 list <string> Fileid::ro_prefix;	// Read-only prefix
-					//
-/*
- * Return the anonymous id, controlling the order of its construction
- * through the "Construct on First Use" idiom.
- */
-Fileid
-Fileid::get_anonymous()
-{
-	static Fileid anonymous(Fileid("ANONYMOUS", 0));
-	return anonymous;
-}
-
-/*
- * Return the map from unique name to id, controlling the order of its
- * construction through the "Construct on First Use" idiom.
- */
-FI_uname_to_id &
-Fileid::get_u2i()
-{
-	static FI_uname_to_id u2i;
-	return u2i;
-}
-
 
 #ifdef WIN32
 // Return the canonical representation of a WIN32 filename character
@@ -128,7 +105,7 @@ Fileid::Fileid(const string &name)
 	string sid(get_uniq_fname_string(name.c_str()));
 	FI_uname_to_id::const_iterator uni;
 
-	if ((uni = get_u2i().find(sid)) != get_u2i().end()) {
+	if ((uni = u2i.find(sid)) != u2i.end()) {
 		// Filename exists; our id is the one from the map
 		id = uni->second;
 	} else {
@@ -137,7 +114,7 @@ Fileid::Fileid(const string &name)
 		unsigned char *h = MD5File(name.c_str());
 		FileHash hash(h, h + 16);
 
-		get_u2i()[sid] = id = counter++;
+		u2i[sid] = id = counter++;
 		Filedetails::add_instance(fpath, is_readonly(name.c_str()), hash);
 
 		Filedetails::add_identical_file(hash, *this);
@@ -146,10 +123,10 @@ Fileid::Fileid(const string &name)
 		cout << "Fileid(" << name << ") = " << id << "\n";
 }
 
-// Used for initialization and testing; not for real files
+// User for initialization and testing; not for real files
 Fileid::Fileid(const string &name, int i)
 {
-	get_u2i()[name] = i;
+	u2i[name] = i;
 	Filedetails::add_instance(name, true, FileHash());
 	id = i;
 	Filedetails::add_identical_file(FileHash(), *this);

src/fileid.h

@@ -29,13 +29,15 @@
 #include <list>
 #include <map>
 #include <set>
+#include <string>
 #include <vector>
 
 using namespace std;
 
 class Fchar;
 class FileMetrics;
 
+typedef vector<unsigned char> FileHash;
 typedef map <string, int> FI_uname_to_id;
 
 /*
@@ -49,19 +51,13 @@ class Fileid {
 	int id;				// One global unique id per workspace file
 
 	static int counter;		// To generate ids
-	// Return map from unique name to id
-	static FI_uname_to_id& get_u2i();
+	static FI_uname_to_id u2i;	// From unique name to id
 
 	// Construct a new Fileid given a name and id value
 	// Only used internally for creating the anonymous id
 	Fileid(const string& name, int id);
-
-	/*
-	 * Return an anonymous id, controlling the order of its construction
-	 * through the "Construct on First Use" idiom.
-	 */
-	static Fileid get_anonymous();
-
+	// An anonymous id
+	static Fileid anonymous;
 	// The prefix for read-only files
 	static list <string> ro_prefix;
 	// And a function to check fnames against it
@@ -73,7 +69,7 @@ class Fileid {
 	// Create it without any checking from an integer
 	Fileid(int i) : id(i) {}
 	// Construct an anonymous Fileid
-	Fileid() { *this = get_anonymous(); };
+	Fileid() { *this = Fileid::anonymous; };
 	// Return the full file path of a given id
 	const string& get_path() const;
 	const string get_fname() const;

src/static_init.cpp

@@ -0,0 +1,60 @@
+/*
+ * (C) Copyright 2024 Diomidis Spinellis
+ *
+ * This file is part of CScout.
+ *
+ * CScout is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * CScout is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with CScout.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Statically initialized values.  C++ only guarantees the initialization
+ * order of values that reside in the same compilation unit (from top to
+ * bottom).  Therefore, define and initialize all related elements here
+ * in the appropriate order.
+ *
+ * The correct order of initialization can be also automatically
+ * guaranted with the "Construct on First Use" idiom, at the cost
+ * however of one non-inlinable function call for each access.
+ * The best wall clock time for cscout -c awk.cs with the current approach
+ * approach is 0.473 s vs 0.484 s for the Construct on First Use approach.
+ *
+ */
+
+#include "fileid.h"
+#include "filedetails.h"
+
+/*
+ * For the following their order is established as follows:
+ * 1. anoynmous object is initialized via the constructor
+ * Fileid::Fileid(const string &name, int i) which:
+ *   1.1 uses u2i
+ *   1.2 calls Filedetails::add_instance(name, true, FileHash()) using i2d
+ *   1.3 calls Filedetails::add_identical_file(FileHash(), *this) using
+ *       Filedetails::identical_files
+ * Initialize from inside (1.X) to outside.
+ */
+
+// Map from unique name to id
+FI_uname_to_id Fileid::u2i;
+
+// Map from id to file details; first element is anonymous
+FI_id_to_details Filedetails::i2d;
+
+// Files that are exact duplicates
+FI_hash_to_ids Filedetails::identical_files;
+
+/*
+ * An object used creating Fileids with an empty initializer,
+ * which is required for initially empty Tokids.
+ */
+Fileid Fileid::anonymous = Fileid("ANONYMOUS", 0);