gdb: add a constructor for symtab

Convert symtab to use obstack_new, and have a real constructor.  The
filename, filename_for_id and m_compunit, members should really not
change once the symtab has been created, so make these members private
(m_compunit was already private) and set them just once from the
constructor.  The set_compunit function has been deleted, and new
getter functions for filename and filename_for_id have been added.

The language is also set at construction time, but can be updated
later, so set the language in the constructor, but retain
symtab::set_language for when the language needs to be updated.

Prior to this patch the symtab was allocated with OBSTACK_ZALLOC which
would zero out the symtab object.  With the call to objstack_new
fields in the symtab would no longer be initialised, so I've added
default member initialisation for everything not set in the
constructor.

The interesting changes are in symtab.h, and symfile.c.  Everything
else is just updating to handle symfile::filename and
symfile::filename_for_id becoming methods.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

gdb/ada-lang.c

@@ -3519,8 +3519,8 @@ sort_choices (std::vector<struct block_symbol> &syms)
 	       if (!b.symbol->is_objfile_owned ())
 		 return true;
 
-	       const char *fna = a.symbol->symtab ()->filename;
-	       const char *fnb = b.symbol->symtab ()->filename;
+	       const char *fna = a.symbol->symtab ()->filename ();
+	       const char *fnb = b.symbol->symtab ()->filename ();
 
 	       /* First sort by basename.  This is done because,
 		  depending on how GNAT was invoked, different sources
@@ -11927,7 +11927,7 @@ is_known_support_routine (const frame_info_ptr &frame)
   for (i = 0; known_runtime_file_name_patterns[i] != NULL; i += 1)
     {
       re_comp (known_runtime_file_name_patterns[i]);
-      if (re_exec (lbasename (sal.symtab->filename)))
+      if (re_exec (lbasename (sal.symtab->filename ())))
 	return 1;
       if (sal.symtab->compunit ()->objfile () != NULL
 	  && re_exec (objfile_name (sal.symtab->compunit ()->objfile ())))

gdb/cli/cli-cmds.c

@@ -2228,7 +2228,7 @@ cmp_symtabs (const symtab_and_line &sala, const symtab_and_line &salb)
 	return r;
     }
 
-  r = filename_cmp (sala.symtab->filename, salb.symtab->filename);
+  r = filename_cmp (sala.symtab->filename (), salb.symtab->filename ());
   if (r)
     return r;
 

gdb/compile/compile-c-symbols.c

@@ -56,7 +56,7 @@ convert_one_symbol (compile_c_instance *context,
 		    int is_local)
 {
   gcc_type sym_type;
-  const char *filename = sym.symbol->symtab ()->filename;
+  const char *filename = sym.symbol->symtab ()->filename ();
   unsigned int line = sym.symbol->line ();
 
   context->error_symbol_once (sym.symbol);

gdb/compile/compile-cplus-symbols.c

@@ -48,7 +48,7 @@ convert_one_symbol (compile_cplus_instance *instance,
 {
   /* Squash compiler warning.  */
   gcc_type sym_type = 0;
-  const char *filename = sym.symbol->symtab ()->filename;
+  const char *filename = sym.symbol->symtab ()->filename ();
   unsigned int line = sym.symbol->line ();
 
   instance->error_symbol_once (sym.symbol);

gdb/compile/compile-cplus-types.c

@@ -624,7 +624,7 @@ compile_cplus_convert_struct_or_union_members
 		       we can do but ignore this member.  */
 		    continue;
 		  }
-		const char *filename = sym.symbol->symtab ()->filename;
+		const char *filename = sym.symbol->symtab ()->filename ();
 		unsigned int line = sym.symbol->line ();
 
 		physaddr = sym.symbol->value_address ();
@@ -763,7 +763,7 @@ compile_cplus_convert_struct_or_union_methods (compile_cplus_instance *instance,
 	      continue;
 	    }
 
-	  const char *filename = sym.symbol->symtab ()->filename;
+	  const char *filename = sym.symbol->symtab ()->filename ();
 	  unsigned int line = sym.symbol->line ();
 	  CORE_ADDR address = sym.symbol->value_block()->start ();
 	  const char *kind;

gdb/infrun.c

@@ -4842,7 +4842,7 @@ set_step_info (thread_info *tp, const frame_info_ptr &frame,
 
   infrun_debug_printf
     ("symtab = %s, line = %d, step_frame_id = %s, step_stack_frame_id = %s",
-     tp->current_symtab != nullptr ? tp->current_symtab->filename : "<null>",
+     tp->current_symtab != nullptr ? tp->current_symtab->filename () : "<null>",
      tp->current_line,
      tp->control.step_frame_id.to_string ().c_str (),
      tp->control.step_stack_frame_id.to_string ().c_str ());

gdb/linespec.c

@@ -2005,7 +2005,7 @@ create_sals_line_offset (struct linespec_state *self,
       set_default_source_symtab_and_line ();
       initialize_defaults (&self->default_symtab, &self->default_line);
       ls->file_symtabs
-	= collect_symtabs_from_filename (self->default_symtab->filename,
+	= collect_symtabs_from_filename (self->default_symtab->filename (),
 					 self->search_pspace);
       use_default = true;
     }
@@ -2291,7 +2291,7 @@ convert_linespec_to_sals (struct linespec_state *state, linespec *ls)
 	/* Make sure we have a filename for canonicalization.  */
 	if (ls->explicit_loc.source_filename == NULL)
 	  {
-	    const char *filename = state->default_symtab->filename;
+	    const char *filename = state->default_symtab->filename ();
 
 	    /* It may be more appropriate to keep DEFAULT_SYMTAB in its symtab
 	       form so that displaying SOURCE_FILENAME can follow the current

gdb/macroscope.c

@@ -51,7 +51,8 @@ sal_macro_scope (struct symtab_and_line sal)
   macro_scope ms;
 
   main_file = macro_main (cust->macro_table ());
-  inclusion = macro_lookup_inclusion (main_file, sal.symtab->filename_for_id);
+  inclusion = macro_lookup_inclusion (main_file,
+				      sal.symtab->filename_for_id ());
 
   if (inclusion)
     {

gdb/python/py-breakpoint.c

@@ -1644,7 +1644,7 @@ bploc_filepath (struct symtab *bploc_symtab)
     {
     }
 
-  return host_string_to_python_string (bploc_symtab->filename);
+  return host_string_to_python_string (bploc_symtab->filename ());
 }
 
 /* Python function to get the source file name path and line number
@@ -1763,7 +1763,7 @@ bplocpy_repr (PyObject *py_self)
 			  paddress (self->bp_loc->owner->gdbarch,
 				    self->bp_loc->requested_address));
   if (self->bp_loc->symtab != nullptr)
-    str += string_printf (" source=%s:%d", self->bp_loc->symtab->filename,
+    str += string_printf (" source=%s:%d", self->bp_loc->symtab->filename (),
 			  self->bp_loc->line_number);
 
   const auto fn_name = self->bp_loc->function_name.get ();

gdb/skip.c

@@ -488,20 +488,20 @@ skiplist_entry::do_skip_file_p (const symtab_and_line &function_sal) const
   if (debug_skip)
     gdb_printf (gdb_stdlog,
 		"skip: checking if file %s matches non-glob %s...",
-		function_sal.symtab->filename, m_file.c_str ());
+		function_sal.symtab->filename (), m_file.c_str ());
 
   bool result;
 
   /* Check first sole SYMTAB->FILENAME.  It may not be a substring of
      symtab_to_fullname as it may contain "./" etc.  */
-  if (compare_filenames_for_search (function_sal.symtab->filename,
+  if (compare_filenames_for_search (function_sal.symtab->filename (),
 				    m_file.c_str ()))
     result = true;
 
   /* Before we invoke realpath, which can get expensive when many
      files are involved, do a quick comparison of the basenames.  */
   else if (!basenames_may_differ
-	   && filename_cmp (lbasename (function_sal.symtab->filename),
+	   && filename_cmp (lbasename (function_sal.symtab->filename ()),
 			    lbasename (m_file.c_str ())) != 0)
     result = false;
   else
@@ -524,13 +524,13 @@ skiplist_entry::do_skip_gfile_p (const symtab_and_line &function_sal) const
   if (debug_skip)
     gdb_printf (gdb_stdlog,
 		"skip: checking if file %s matches glob %s...",
-		function_sal.symtab->filename, m_file.c_str ());
+		function_sal.symtab->filename (), m_file.c_str ());
 
   bool result;
 
   /* Check first sole SYMTAB->FILENAME.  It may not be a substring of
      symtab_to_fullname as it may contain "./" etc.  */
-  if (gdb_filename_fnmatch (m_file.c_str (), function_sal.symtab->filename,
+  if (gdb_filename_fnmatch (m_file.c_str (), function_sal.symtab->filename (),
 			    FNM_NOESCAPE) == 0)
     result = true;
 
@@ -541,7 +541,7 @@ skiplist_entry::do_skip_gfile_p (const symtab_and_line &function_sal) const
      isn't much of a win.  Oh well.  */
   else if (!basenames_may_differ
       && gdb_filename_fnmatch (lbasename (m_file.c_str ()),
-			       lbasename (function_sal.symtab->filename),
+			       lbasename (function_sal.symtab->filename ()),
 			       FNM_NOESCAPE) != 0)
     result = false;
   else

gdb/source.c

@@ -342,7 +342,7 @@ select_source_symtab ()
 	{
 	  for (symtab *symtab : cu.filetabs ())
 	    {
-	      const char *name = symtab->filename;
+	      const char *name = symtab->filename ();
 	      int len = strlen (name);
 
 	      if (!(len > 2 && (strcmp (&name[len - 2], ".h") == 0
@@ -683,7 +683,7 @@ info_source_command (const char *ignore, int from_tty)
     }
 
   cust = s->compunit ();
-  gdb_printf (_("Current source file is %s\n"), s->filename);
+  gdb_printf (_("Current source file is %s\n"), s->filename ());
   if (s->compunit ()->dirname () != NULL)
     gdb_printf (_("Compilation directory is %s\n"), s->compunit ()->dirname ());
   if (s->fullname () != nullptr)
@@ -1119,7 +1119,8 @@ open_source_file (struct symtab *s)
     return scoped_fd (-EINVAL);
 
   gdb::unique_xmalloc_ptr<char> fullname = s->release_fullname ();
-  scoped_fd fd = find_and_open_source (s->filename, s->compunit ()->dirname (),
+  scoped_fd fd = find_and_open_source (s->filename (),
+				       s->compunit ()->dirname (),
 				       &fullname);
 
   if (fd.get () < 0)
@@ -1129,13 +1130,13 @@ open_source_file (struct symtab *s)
 	  const objfile *ofp = s->compunit ()->objfile ();
 
 	  std::string srcpath;
-	  if (IS_ABSOLUTE_PATH (s->filename))
-	    srcpath = s->filename;
+	  if (IS_ABSOLUTE_PATH (s->filename ()))
+	    srcpath = s->filename ();
 	  else if (s->compunit ()->dirname () != nullptr)
 	    {
 	      srcpath = s->compunit ()->dirname ();
 	      srcpath += SLASH_STRING;
-	      srcpath += s->filename;
+	      srcpath += s->filename ();
 	    }
 
 	  const struct bfd_build_id *build_id
@@ -1220,11 +1221,11 @@ symtab_to_fullname (struct symtab *s)
 	     should report the pathname where GDB tried to find the file.  */
 
 	  if (s->compunit ()->dirname () == nullptr
-	      || IS_ABSOLUTE_PATH (s->filename))
-	    fullname.reset (xstrdup (s->filename));
+	      || IS_ABSOLUTE_PATH (s->filename ()))
+	    fullname.reset (xstrdup (s->filename ()));
 	  else
 	    fullname.reset (concat (s->compunit ()->dirname (), SLASH_STRING,
-				    s->filename, (char *) NULL));
+				    s->filename (), (char *) NULL));
 
 	  s->set_fullname (rewrite_source_path (fullname.get ()));
 	  if (s->fullname () == nullptr)
@@ -1241,11 +1242,11 @@ const char *
 symtab_to_filename_for_display (struct symtab *symtab)
 {
   if (filename_display_string == filename_display_basename)
-    return lbasename (symtab->filename);
+    return lbasename (symtab->filename ());
   else if (filename_display_string == filename_display_absolute)
     return symtab_to_fullname (symtab);
   else if (filename_display_string == filename_display_relative)
-    return symtab->filename;
+    return symtab->filename ();
   else
     internal_error (_("invalid filename_display_string"));
 }

gdb/symfile-debug.c

@@ -184,7 +184,7 @@ iterate_over_one_compunit_symtab (const char *name,
 
   for (symtab *s : cust->filetabs ())
     {
-      if (compare_filenames_for_search (s->filename, name))
+      if (compare_filenames_for_search (s->filename (), name))
 	{
 	  if (callback (s))
 	    return true;
@@ -194,7 +194,7 @@ iterate_over_one_compunit_symtab (const char *name,
       /* Before we invoke realpath, which can get expensive when many
 	 files are involved, do a quick comparison of the basenames.  */
       if (! basenames_may_differ
-	  && FILENAME_CMP (base_name, lbasename (s->filename)) != 0)
+	  && FILENAME_CMP (base_name, lbasename (s->filename ())) != 0)
 	continue;
 
       if (compare_filenames_for_search (symtab_to_fullname (s), name))

gdb/symfile.c

@@ -2830,11 +2830,11 @@ allocate_symtab (struct compunit_symtab *cust, const char *filename,
 {
   struct objfile *objfile = cust->objfile ();
   struct symtab *symtab
-    = OBSTACK_ZALLOC (&objfile->objfile_obstack, struct symtab);
-
-  symtab->filename = objfile->intern (filename);
-  symtab->filename_for_id = objfile->intern (filename_for_id);
-  symtab->set_language (deduce_language_from_filename (filename));
+    = obstack_new<struct symtab> (&objfile->objfile_obstack,
+				  cust,
+				  objfile->intern (filename),
+				  objfile->intern (filename_for_id),
+				  deduce_language_from_filename (filename));
 
   /* This can be very verbose with lots of headers.
      Only print at higher debug levels.  */
@@ -2860,9 +2860,6 @@ allocate_symtab (struct compunit_symtab *cust, const char *filename,
   /* Add it to CUST's list of symtabs.  */
   cust->add_filetab (symtab);
 
-  /* Backlink to the containing compunit symtab.  */
-  symtab->set_compunit (cust);
-
   return symtab;
 }
 

gdb/symtab.c

@@ -3309,7 +3309,7 @@ find_line_symtab (symtab *sym_tab, int line, int *index)
 		  const struct linetable *l;
 		  int ind;
 
-		  if (FILENAME_CMP (sym_tab->filename, s->filename) != 0)
+		  if (FILENAME_CMP (sym_tab->filename (), s->filename ()) != 0)
 		    continue;
 		  if (FILENAME_CMP (symtab_to_fullname (sym_tab),
 				    symtab_to_fullname (s)) != 0)
@@ -4627,8 +4627,8 @@ symbol_search::compare_search_syms (const symbol_search &sym_a,
 {
   int c;
 
-  c = FILENAME_CMP (sym_a.symbol->symtab ()->filename,
-		    sym_b.symbol->symtab ()->filename);
+  c = FILENAME_CMP (sym_a.symbol->symtab ()->filename (),
+		    sym_b.symbol->symtab ()->filename ());
   if (c != 0)
     return c;
 
@@ -4802,9 +4802,9 @@ global_symbol_searcher::add_matching_symbols
 	      /* Check first sole REAL_SYMTAB->FILENAME.  It does
 		 not need to be a substring of symtab_to_fullname as
 		 it may contain "./" etc.  */
-	      if (!(file_matches (real_symtab->filename, m_filenames, false)
+	      if (!(file_matches (real_symtab->filename (), m_filenames, false)
 		    || ((basenames_may_differ
-			 || file_matches (lbasename (real_symtab->filename),
+			 || file_matches (lbasename (real_symtab->filename ()),
 					  m_filenames, true))
 			&& file_matches (symtab_to_fullname (real_symtab),
 					 m_filenames, false))))
@@ -6220,14 +6220,14 @@ make_source_files_completion_list (const char *text)
 	{
 	  for (symtab *s : cu.filetabs ())
 	    {
-	      if (not_interesting_fname (s->filename))
+	      if (not_interesting_fname (s->filename ()))
 		continue;
-	      if (!filenames_seen.seen (s->filename)
-		  && filename_ncmp (s->filename, text, text_len) == 0)
+	      if (!filenames_seen.seen (s->filename ())
+		  && filename_ncmp (s->filename (), text, text_len) == 0)
 		{
 		  /* This file matches for a completion; add it to the current
 		     list of matches.  */
-		  add_filename_to_list (s->filename, text, text, &list);
+		  add_filename_to_list (s->filename (), text, text, &list);
 		}
 	      else
 		{
@@ -6235,8 +6235,8 @@ make_source_files_completion_list (const char *text)
 		     debug info records leading directories, but not the other
 		     way around.  This is what subroutines of breakpoint
 		     command do when they parse file names.  */
-		  base_name = lbasename (s->filename);
-		  if (base_name != s->filename
+		  base_name = lbasename (s->filename ());
+		  if (base_name != s->filename ()
 		      && !filenames_seen.seen (base_name)
 		      && filename_ncmp (base_name, text, text_len) == 0)
 		    add_filename_to_list (base_name, text, text, &list);

gdb/symtab.h

@@ -1698,16 +1698,23 @@ typedef std::vector<CORE_ADDR> section_offsets;
 
 struct symtab
 {
+  symtab (struct compunit_symtab *cust, const char *filename,
+	  const char *filename_for_id, enum language language)
+    : m_filename (filename),
+      m_filename_for_id (filename_for_id),
+      m_compunit (cust),
+      m_language (language)
+  {
+    gdb_assert (m_filename != nullptr);
+    gdb_assert (m_filename_for_id != nullptr);
+    gdb_assert (m_compunit != nullptr);
+  }
+
   struct compunit_symtab *compunit () const
   {
     return m_compunit;
   }
 
-  void set_compunit (struct compunit_symtab *compunit)
-  {
-    m_compunit = compunit;
-  }
-
   const struct linetable *linetable () const
   {
     return m_linetable;
@@ -1749,16 +1756,24 @@ struct symtab
     m_fullname = name.release ();
   }
 
+  const char *filename () const
+  { return m_filename; }
+
+  const char *filename_for_id () const
+  { return m_filename_for_id; }
+
   /* Unordered chain of all filetabs in the compunit,  with the exception
      that the "main" source file is the first entry in the list.  */
 
-  struct symtab *next;
+  struct symtab *next = nullptr;
+
+private:
 
   /* Name of this source file, in a form appropriate to print to the user.
 
-     This pointer is never nullptr.  */
+     This pointer is never nullptr and is set from the constructor.  */
 
-  const char *filename;
+  const char *m_filename;
 
   /* Filename for this source file, used as an identifier to link with
      related objects such as associated macro_source_file objects.  It must
@@ -1767,28 +1782,29 @@ struct symtab
      follow that rule, or another form of the same file name, this is up to
      the specific debug info reader.
 
-     This pointer is never nullptr.*/
-  const char *filename_for_id;
+     This pointer is never nullptr, and is set from the constructor.  */
+  const char *m_filename_for_id;
 
-private:
+  /* Backlink to containing compunit symtab.
 
-  /* Backlink to containing compunit symtab.  */
+     This pointer is never nullptr, and is set from the constructor.  */
 
   struct compunit_symtab *m_compunit;
 
   /* Table mapping core addresses to line numbers for this file.
      Can be NULL if none.  Never shared between different symtabs.  */
 
-  const struct linetable *m_linetable;
+  const struct linetable *m_linetable = nullptr;
 
-  /* Language of this source file.  */
+  /* Language of this source file.  This is set in the object
+     constructor.  */
 
   enum language m_language;
 
   /* Full name of file as found by searching the source path.
      NULL if not yet known.  */
 
-  char *m_fullname;
+  char *m_fullname = nullptr;
 };
 
 /* A range adapter to allowing iterating over all the file tables in a list.  */