[PATCH 25/26] Switch objfile to hold a list of psymbol readers

[Tom Tromey <tom@tromey.com>]

This changes objfile::qf to be a forward_list, and then updates all
the uses to iterate over the list.  Note that there is still only ever
a single element in the list; this is handled by clearing the list
whenever an object is added.

gdb/ChangeLog
2021-02-28  Tom Tromey  <tom@tromey.com>

	* dwarf2/read.c (dwarf2_build_psymtabs): Update.
	* symfile.c (syms_from_objfile_1, reread_symbols): Update.
	* symfile-debug.c (objfile::has_partial_symbols)
	(objfile::find_last_source_symtab)
	(objfile::forget_cached_source_info)
	(objfile::map_symtabs_matching_filename, objfile::lookup_symbol)
	(objfile::print_stats, objfile::dump)
	(objfile::expand_symtabs_for_function)
	(objfile::expand_all_symtabs)
	(objfile::expand_symtabs_with_fullname)
	(objfile::map_matching_symbols)
	(objfile::expand_symtabs_matching)
	(objfile::find_pc_sect_compunit_symtab)
	(objfile::map_symbol_filenames)
	(objfile::find_compunit_symtab_by_address)
	(objfile::lookup_global_symbol_language)
	(objfile::require_partial_symbols): Update.
	* psymtab.c (maintenance_print_psymbols)
	(maintenance_info_psymtabs, maintenance_check_psymtabs): Update.
	* objfiles.h (struct objfile) <qf>: Now a forward_list.
	* objfiles.c (objfile_relocate1): Update.
	* elfread.c (elf_symfile_read): Update.
---
 gdb/ChangeLog       |  25 +++
 gdb/dwarf2/read.c   |   2 +-
 gdb/elfread.c       |   9 +-
 gdb/objfiles.c      |   4 +-
 gdb/objfiles.h      |   3 +-
 gdb/psymtab.c       | 412 +++++++++++++++++++++++---------------------
 gdb/symfile-debug.c | 137 +++++++++------
 gdb/symfile.c       |   7 +-
 8 files changed, 337 insertions(+), 262 deletions(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 183876bb5b7..570df071bf7 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -6361,7 +6361,7 @@ dwarf2_build_psymtabs (struct objfile *objfile)
       /* This is a temporary hack to ensure that the objfile and 'qf'
 	 psymtabs are identical.  */
       psymbol_functions *psf
-	= dynamic_cast<psymbol_functions *> (objfile->qf.get ());
+	= dynamic_cast<psymbol_functions *> (objfile->qf.front ().get ());
       gdb_assert (psf != nullptr);
       psf->set_partial_symtabs (per_bfd->partial_symtabs);
       per_objfile->resize_symtabs ();
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 157a0717828..1cf9b2addc4 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1287,10 +1287,12 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 	  switch (index_kind)
 	    {
 	    case dw_index_kind::GDB_INDEX:
-	      objfile->qf = make_dwarf_gdb_index ();
+	      objfile->qf.clear ();
+	      objfile->qf.push_front (make_dwarf_gdb_index ());
 	      break;
 	    case dw_index_kind::DEBUG_NAMES:
-	      objfile->qf = make_dwarf_debug_names ();
+	      objfile->qf.clear ();
+	      objfile->qf.push_front (make_dwarf_debug_names ());
 	      break;
 	    }
 	}
@@ -1300,7 +1302,8 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 	     partial symbols, because OBJF_PSYMTABS_READ has not been
 	     set, and so our lazy reader function will still be called
 	     when needed.  */
-	  objfile->qf.reset
+	  objfile->qf.clear ();
+	  objfile->qf.emplace_front
 	    (new lazy_dwarf_reader (objfile->partial_symtabs));
 	}
     }
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index ca135dd63c3..ed51c31c8b9 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -703,8 +703,8 @@ objfile_relocate1 (struct objfile *objfile,
   }
 
   /* Notify the quick symbol object.  */
-  if (objfile->qf)
-    objfile->qf->relocated ();
+  for (const auto &iter : objfile->qf)
+    iter->relocated ();
 
   /* Relocate isolated symbols.  */
   {
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index cb441b117df..2f566709eb2 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -38,6 +38,7 @@
 #include "gdbsupport/refcounted-object.h"
 #include "jit.h"
 #include "quick-symbol.h"
+#include <forward_list>
 
 struct htab;
 struct objfile_data;
@@ -668,7 +669,7 @@ struct objfile
 
   /* The "quick" (aka partial) symbol functions for this symbol
      reader.  */
-  quick_symbol_functions_up qf;
+  std::forward_list<quick_symbol_functions_up> qf;
 
   /* Per objfile data-pointers required by other GDB modules.  */
 
diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index 3f3b5596864..785eda04c9e 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -1810,49 +1810,25 @@ maintenance_print_psymbols (const char *args, int from_tty)
       if (!print_for_objfile)
 	continue;
 
-      psymbol_functions *psf
-	= dynamic_cast<psymbol_functions *> (objfile->qf.get ());
-      if (psf == nullptr)
-	continue;
-
-      psymtab_storage *partial_symtabs = psf->get_partial_symtabs ().get ();
-
-      if (address_arg != NULL)
+      for (const auto &iter : objfile->qf)
 	{
-	  struct bound_minimal_symbol msymbol = { NULL, NULL };
+	  psymbol_functions *psf
+	    = dynamic_cast<psymbol_functions *> (iter.get ());
+	  if (psf == nullptr)
+	    continue;
 
-	  /* We don't assume each pc has a unique objfile (this is for
-	     debugging).  */
-	  struct partial_symtab *ps
-	    = psf->find_pc_sect_psymtab (objfile, pc, section, msymbol);
-	  if (ps != NULL)
-	    {
-	      if (!printed_objfile_header)
-		{
-		  outfile->printf ("\nPartial symtabs for objfile %s\n",
-				  objfile_name (objfile));
-		  printed_objfile_header = 1;
-		}
-	      dump_psymtab (objfile, ps, outfile);
-	      dump_psymtab_addrmap (objfile, partial_symtabs, ps, outfile);
-	      found = 1;
-	    }
-	}
-      else
-	{
-	  for (partial_symtab *ps : psf->require_partial_symbols (objfile))
+	  psymtab_storage *partial_symtabs
+	    = psf->get_partial_symtabs ().get ();
+
+	  if (address_arg != NULL)
 	    {
-	      int print_for_source = 0;
+	      struct bound_minimal_symbol msymbol = { NULL, NULL };
 
-	      QUIT;
-	      if (source_arg != NULL)
-		{
-		  print_for_source
-		    = compare_filenames_for_search (ps->filename, source_arg);
-		  found = 1;
-		}
-	      if (source_arg == NULL
-		  || print_for_source)
+	      /* We don't assume each pc has a unique objfile (this is for
+		 debugging).  */
+	      struct partial_symtab *ps
+		= psf->find_pc_sect_psymtab (objfile, pc, section, msymbol);
+	      if (ps != NULL)
 		{
 		  if (!printed_objfile_header)
 		    {
@@ -1861,20 +1837,48 @@ maintenance_print_psymbols (const char *args, int from_tty)
 		      printed_objfile_header = 1;
 		    }
 		  dump_psymtab (objfile, ps, outfile);
-		  dump_psymtab_addrmap (objfile, partial_symtabs, ps,
-					outfile);
+		  dump_psymtab_addrmap (objfile, partial_symtabs, ps, outfile);
+		  found = 1;
+		}
+	    }
+	  else
+	    {
+	      for (partial_symtab *ps : psf->require_partial_symbols (objfile))
+		{
+		  int print_for_source = 0;
+
+		  QUIT;
+		  if (source_arg != NULL)
+		    {
+		      print_for_source
+			= compare_filenames_for_search (ps->filename, source_arg);
+		      found = 1;
+		    }
+		  if (source_arg == NULL
+		      || print_for_source)
+		    {
+		      if (!printed_objfile_header)
+			{
+			  outfile->printf ("\nPartial symtabs for objfile %s\n",
+					   objfile_name (objfile));
+			  printed_objfile_header = 1;
+			}
+		      dump_psymtab (objfile, ps, outfile);
+		      dump_psymtab_addrmap (objfile, partial_symtabs, ps,
+					    outfile);
+		    }
 		}
 	    }
-	}
 
-      /* If we're printing all the objfile's symbols dump the full addrmap.  */
+	  /* If we're printing all the objfile's symbols dump the full addrmap.  */
 
-      if (address_arg == NULL
-	  && source_arg == NULL
-	  && partial_symtabs->psymtabs_addrmap != NULL)
-	{
-	  outfile->puts ("\n");
-	  dump_psymtab_addrmap (objfile, partial_symtabs, NULL, outfile);
+	  if (address_arg == NULL
+	      && source_arg == NULL
+	      && partial_symtabs->psymtabs_addrmap != NULL)
+	    {
+	      outfile->puts ("\n");
+	      dump_psymtab_addrmap (objfile, partial_symtabs, NULL, outfile);
+	    }
 	}
     }
 
@@ -1904,91 +1908,94 @@ maintenance_info_psymtabs (const char *regexp, int from_tty)
 	   actually find a symtab whose name matches.  */
 	int printed_objfile_start = 0;
 
-	psymbol_functions *psf
-	  = dynamic_cast<psymbol_functions *> (objfile->qf.get ());
-	if (psf == nullptr)
-	  continue;
-	for (partial_symtab *psymtab : psf->require_partial_symbols (objfile))
+	for (const auto &iter : objfile->qf)
 	  {
-	    QUIT;
-
-	    if (! regexp
-		|| re_exec (psymtab->filename))
+	    psymbol_functions *psf
+	      = dynamic_cast<psymbol_functions *> (iter.get ());
+	    if (psf == nullptr)
+	      continue;
+	    for (partial_symtab *psymtab : psf->require_partial_symbols (objfile))
 	      {
-		if (! printed_objfile_start)
-		  {
-		    printf_filtered ("{ objfile %s ", objfile_name (objfile));
-		    wrap_here ("  ");
-		    printf_filtered ("((struct objfile *) %s)\n",
-				     host_address_to_string (objfile));
-		    printed_objfile_start = 1;
-		  }
+		QUIT;
 
-		printf_filtered ("  { psymtab %s ", psymtab->filename);
-		wrap_here ("    ");
-		printf_filtered ("((struct partial_symtab *) %s)\n",
-				 host_address_to_string (psymtab));
-
-		printf_filtered ("    readin %s\n",
-				 psymtab->readin_p (objfile) ? "yes" : "no");
-		printf_filtered ("    fullname %s\n",
-				 psymtab->fullname
-				 ? psymtab->fullname : "(null)");
-		printf_filtered ("    text addresses ");
-		fputs_filtered (paddress (gdbarch,
-					  psymtab->text_low (objfile)),
-				gdb_stdout);
-		printf_filtered (" -- ");
-		fputs_filtered (paddress (gdbarch,
-					  psymtab->text_high (objfile)),
-				gdb_stdout);
-		printf_filtered ("\n");
-		printf_filtered ("    psymtabs_addrmap_supported %s\n",
-				 (psymtab->psymtabs_addrmap_supported
-				  ? "yes" : "no"));
-		printf_filtered ("    globals ");
-		if (!psymtab->global_psymbols.empty ())
-		  printf_filtered
-		    ("(* (struct partial_symbol **) %s @ %d)\n",
-		     host_address_to_string (psymtab->global_psymbols.data ()),
-		     (int) psymtab->global_psymbols.size ());
-		else
-		  printf_filtered ("(none)\n");
-		printf_filtered ("    statics ");
-		if (!psymtab->static_psymbols.empty ())
-		  printf_filtered
-		    ("(* (struct partial_symbol **) %s @ %d)\n",
-		     host_address_to_string (psymtab->static_psymbols.data ()),
-		     (int) psymtab->static_psymbols.size ());
-		else
-		  printf_filtered ("(none)\n");
-		if (psymtab->user)
-		  printf_filtered ("    user %s "
-				   "((struct partial_symtab *) %s)\n",
-				   psymtab->user->filename,
-				   host_address_to_string (psymtab->user));
-		printf_filtered ("    dependencies ");
-		if (psymtab->number_of_dependencies)
+		if (! regexp
+		    || re_exec (psymtab->filename))
 		  {
-		    int i;
+		    if (! printed_objfile_start)
+		      {
+			printf_filtered ("{ objfile %s ", objfile_name (objfile));
+			wrap_here ("  ");
+			printf_filtered ("((struct objfile *) %s)\n",
+					 host_address_to_string (objfile));
+			printed_objfile_start = 1;
+		      }
 
-		    printf_filtered ("{\n");
-		    for (i = 0; i < psymtab->number_of_dependencies; i++)
+		    printf_filtered ("  { psymtab %s ", psymtab->filename);
+		    wrap_here ("    ");
+		    printf_filtered ("((struct partial_symtab *) %s)\n",
+				     host_address_to_string (psymtab));
+
+		    printf_filtered ("    readin %s\n",
+				     psymtab->readin_p (objfile) ? "yes" : "no");
+		    printf_filtered ("    fullname %s\n",
+				     psymtab->fullname
+				     ? psymtab->fullname : "(null)");
+		    printf_filtered ("    text addresses ");
+		    fputs_filtered (paddress (gdbarch,
+					      psymtab->text_low (objfile)),
+				    gdb_stdout);
+		    printf_filtered (" -- ");
+		    fputs_filtered (paddress (gdbarch,
+					      psymtab->text_high (objfile)),
+				    gdb_stdout);
+		    printf_filtered ("\n");
+		    printf_filtered ("    psymtabs_addrmap_supported %s\n",
+				     (psymtab->psymtabs_addrmap_supported
+				      ? "yes" : "no"));
+		    printf_filtered ("    globals ");
+		    if (!psymtab->global_psymbols.empty ())
+		      printf_filtered
+			("(* (struct partial_symbol **) %s @ %d)\n",
+			 host_address_to_string (psymtab->global_psymbols.data ()),
+			 (int) psymtab->global_psymbols.size ());
+		    else
+		      printf_filtered ("(none)\n");
+		    printf_filtered ("    statics ");
+		    if (!psymtab->static_psymbols.empty ())
+		      printf_filtered
+			("(* (struct partial_symbol **) %s @ %d)\n",
+			 host_address_to_string (psymtab->static_psymbols.data ()),
+			 (int) psymtab->static_psymbols.size ());
+		    else
+		      printf_filtered ("(none)\n");
+		    if (psymtab->user)
+		      printf_filtered ("    user %s "
+				       "((struct partial_symtab *) %s)\n",
+				       psymtab->user->filename,
+				       host_address_to_string (psymtab->user));
+		    printf_filtered ("    dependencies ");
+		    if (psymtab->number_of_dependencies)
 		      {
-			struct partial_symtab *dep = psymtab->dependencies[i];
-
-			/* Note the string concatenation there --- no
-			   comma.  */
-			printf_filtered ("      psymtab %s "
-					 "((struct partial_symtab *) %s)\n",
-					 dep->filename,
-					 host_address_to_string (dep));
+			int i;
+
+			printf_filtered ("{\n");
+			for (i = 0; i < psymtab->number_of_dependencies; i++)
+			  {
+			    struct partial_symtab *dep = psymtab->dependencies[i];
+
+			    /* Note the string concatenation there --- no
+			       comma.  */
+			    printf_filtered ("      psymtab %s "
+					     "((struct partial_symtab *) %s)\n",
+					     dep->filename,
+					     host_address_to_string (dep));
+			  }
+			printf_filtered ("    }\n");
 		      }
-		    printf_filtered ("    }\n");
+		    else
+		      printf_filtered ("(none)\n");
+		    printf_filtered ("  }\n");
 		  }
-		else
-		  printf_filtered ("(none)\n");
-		printf_filtered ("  }\n");
 	      }
 	  }
 
@@ -2009,93 +2016,96 @@ maintenance_check_psymtabs (const char *ignore, int from_tty)
 
   for (objfile *objfile : current_program_space->objfiles ())
     {
-      psymbol_functions *psf
-	= dynamic_cast<psymbol_functions *> (objfile->qf.get ());
-      if (psf == nullptr)
-	continue;
-
-      for (partial_symtab *ps : psf->require_partial_symbols (objfile))
+      for (const auto &iter : objfile->qf)
 	{
-	  struct gdbarch *gdbarch = objfile->arch ();
-
-	  /* We don't call psymtab_to_symtab here because that may cause symtab
-	     expansion.  When debugging a problem it helps if checkers leave
-	     things unchanged.  */
-	  cust = ps->get_compunit_symtab (objfile);
+	  psymbol_functions *psf
+	    = dynamic_cast<psymbol_functions *> (iter.get ());
+	  if (psf == nullptr)
+	    continue;
 
-	  /* First do some checks that don't require the associated symtab.  */
-	  if (ps->text_high (objfile) < ps->text_low (objfile))
+	  for (partial_symtab *ps : psf->require_partial_symbols (objfile))
 	    {
-	      printf_filtered ("Psymtab ");
-	      puts_filtered (ps->filename);
-	      printf_filtered (" covers bad range ");
-	      fputs_filtered (paddress (gdbarch, ps->text_low (objfile)),
-			      gdb_stdout);
-	      printf_filtered (" - ");
-	      fputs_filtered (paddress (gdbarch, ps->text_high (objfile)),
-			      gdb_stdout);
-	      printf_filtered ("\n");
-	      continue;
-	    }
+	      struct gdbarch *gdbarch = objfile->arch ();
 
-	  /* Now do checks requiring the associated symtab.  */
-	  if (cust == NULL)
-	    continue;
-	  bv = COMPUNIT_BLOCKVECTOR (cust);
-	  b = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
-	  for (partial_symbol *psym : ps->static_psymbols)
-	    {
-	      /* Skip symbols for inlined functions without address.  These may
-		 or may not have a match in the full symtab.  */
-	      if (psym->aclass == LOC_BLOCK
-		  && psym->ginfo.value.address == 0)
-		continue;
+	      /* We don't call psymtab_to_symtab here because that may cause symtab
+		 expansion.  When debugging a problem it helps if checkers leave
+		 things unchanged.  */
+	      cust = ps->get_compunit_symtab (objfile);
 
-	      sym = block_lookup_symbol (b, psym->ginfo.search_name (),
-					 symbol_name_match_type::SEARCH_NAME,
-					 psym->domain);
-	      if (!sym)
+	      /* First do some checks that don't require the associated symtab.  */
+	      if (ps->text_high (objfile) < ps->text_low (objfile))
 		{
-		  printf_filtered ("Static symbol `");
-		  puts_filtered (psym->ginfo.linkage_name ());
-		  printf_filtered ("' only found in ");
+		  printf_filtered ("Psymtab ");
 		  puts_filtered (ps->filename);
-		  printf_filtered (" psymtab\n");
+		  printf_filtered (" covers bad range ");
+		  fputs_filtered (paddress (gdbarch, ps->text_low (objfile)),
+				  gdb_stdout);
+		  printf_filtered (" - ");
+		  fputs_filtered (paddress (gdbarch, ps->text_high (objfile)),
+				  gdb_stdout);
+		  printf_filtered ("\n");
+		  continue;
 		}
-	    }
-	  b = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
-	  for (partial_symbol *psym : ps->global_psymbols)
-	    {
-	      sym = block_lookup_symbol (b, psym->ginfo.search_name (),
-					 symbol_name_match_type::SEARCH_NAME,
-					 psym->domain);
-	      if (!sym)
+
+	      /* Now do checks requiring the associated symtab.  */
+	      if (cust == NULL)
+		continue;
+	      bv = COMPUNIT_BLOCKVECTOR (cust);
+	      b = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
+	      for (partial_symbol *psym : ps->static_psymbols)
+		{
+		  /* Skip symbols for inlined functions without address.  These may
+		     or may not have a match in the full symtab.  */
+		  if (psym->aclass == LOC_BLOCK
+		      && psym->ginfo.value.address == 0)
+		    continue;
+
+		  sym = block_lookup_symbol (b, psym->ginfo.search_name (),
+					     symbol_name_match_type::SEARCH_NAME,
+					     psym->domain);
+		  if (!sym)
+		    {
+		      printf_filtered ("Static symbol `");
+		      puts_filtered (psym->ginfo.linkage_name ());
+		      printf_filtered ("' only found in ");
+		      puts_filtered (ps->filename);
+		      printf_filtered (" psymtab\n");
+		    }
+		}
+	      b = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+	      for (partial_symbol *psym : ps->global_psymbols)
+		{
+		  sym = block_lookup_symbol (b, psym->ginfo.search_name (),
+					     symbol_name_match_type::SEARCH_NAME,
+					     psym->domain);
+		  if (!sym)
+		    {
+		      printf_filtered ("Global symbol `");
+		      puts_filtered (psym->ginfo.linkage_name ());
+		      printf_filtered ("' only found in ");
+		      puts_filtered (ps->filename);
+		      printf_filtered (" psymtab\n");
+		    }
+		}
+	      if (ps->raw_text_high () != 0
+		  && (ps->text_low (objfile) < BLOCK_START (b)
+		      || ps->text_high (objfile) > BLOCK_END (b)))
 		{
-		  printf_filtered ("Global symbol `");
-		  puts_filtered (psym->ginfo.linkage_name ());
-		  printf_filtered ("' only found in ");
+		  printf_filtered ("Psymtab ");
 		  puts_filtered (ps->filename);
-		  printf_filtered (" psymtab\n");
+		  printf_filtered (" covers ");
+		  fputs_filtered (paddress (gdbarch, ps->text_low (objfile)),
+				  gdb_stdout);
+		  printf_filtered (" - ");
+		  fputs_filtered (paddress (gdbarch, ps->text_high (objfile)),
+				  gdb_stdout);
+		  printf_filtered (" but symtab covers only ");
+		  fputs_filtered (paddress (gdbarch, BLOCK_START (b)), gdb_stdout);
+		  printf_filtered (" - ");
+		  fputs_filtered (paddress (gdbarch, BLOCK_END (b)), gdb_stdout);
+		  printf_filtered ("\n");
 		}
 	    }
-	  if (ps->raw_text_high () != 0
-	      && (ps->text_low (objfile) < BLOCK_START (b)
-		  || ps->text_high (objfile) > BLOCK_END (b)))
-	    {
-	      printf_filtered ("Psymtab ");
-	      puts_filtered (ps->filename);
-	      printf_filtered (" covers ");
-	      fputs_filtered (paddress (gdbarch, ps->text_low (objfile)),
-			      gdb_stdout);
-	      printf_filtered (" - ");
-	      fputs_filtered (paddress (gdbarch, ps->text_high (objfile)),
-			      gdb_stdout);
-	      printf_filtered (" but symtab covers only ");
-	      fputs_filtered (paddress (gdbarch, BLOCK_START (b)), gdb_stdout);
-	      printf_filtered (" - ");
-	      fputs_filtered (paddress (gdbarch, BLOCK_END (b)), gdb_stdout);
-	      printf_filtered ("\n");
-	    }
 	}
     }
 }
diff --git a/gdb/symfile-debug.c b/gdb/symfile-debug.c
index 99974536bf4..3daede88292 100644
--- a/gdb/symfile-debug.c
+++ b/gdb/symfile-debug.c
@@ -80,12 +80,16 @@ objfile::has_partial_symbols ()
      them, then that is an indication that they are in fact available.  Without
      this function the symbols may have been already read in but they also may
      not be present in this objfile.  */
-  if ((flags & OBJF_PSYMTABS_READ) == 0
-      && qf != nullptr
-      && qf->can_lazily_read_symbols ())
-    retval = true;
-  else if (qf != nullptr)
-    retval = qf->has_symbols (this);
+  for (const auto &iter : qf)
+    {
+      if ((flags & OBJF_PSYMTABS_READ) == 0
+	  && iter->can_lazily_read_symbols ())
+	retval = true;
+      else
+	retval = iter->has_symbols (this);
+      if (retval)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog, "qf->has_symbols (%s) = %d\n",
@@ -103,8 +107,12 @@ objfile::find_last_source_symtab ()
     fprintf_filtered (gdb_stdlog, "qf->find_last_source_symtab (%s)\n",
 		      objfile_debug_name (this));
 
-  if (qf != nullptr)
-    retval = qf->find_last_source_symtab (this);
+  for (const auto &iter : qf)
+    {
+      retval = iter->find_last_source_symtab (this);
+      if (retval != nullptr)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog, "qf->find_last_source_symtab (...) = %s\n",
@@ -120,8 +128,8 @@ objfile::forget_cached_source_info ()
     fprintf_filtered (gdb_stdlog, "qf->forget_cached_source_info (%s)\n",
 		      objfile_debug_name (this));
 
-  if (qf != nullptr)
-    qf->forget_cached_source_info (this);
+  for (const auto &iter : qf)
+    iter->forget_cached_source_info (this);
 }
 
 bool
@@ -138,9 +146,13 @@ objfile::map_symtabs_matching_filename
 		      host_address_to_string (&callback));
 
   bool retval = false;
-  if (qf != nullptr)
-    retval = (qf->map_symtabs_matching_filename
-	      (this, name, real_path, callback));
+  for (const auto &iter : qf)
+    {
+      retval = (iter->map_symtabs_matching_filename
+		(this, name, real_path, callback));
+      if (retval)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog,
@@ -161,8 +173,12 @@ objfile::lookup_symbol (block_enum kind, const char *name, domain_enum domain)
 		      objfile_debug_name (this), kind, name,
 		      domain_name (domain));
 
-  if (qf != nullptr)
-    retval = qf->lookup_symbol (this, kind, name, domain);
+  for (const auto &iter : qf)
+    {
+      retval = iter->lookup_symbol (this, kind, name, domain);
+      if (retval != nullptr)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog, "qf->lookup_symbol (...) = %s\n",
@@ -180,8 +196,8 @@ objfile::print_stats (bool print_bcache)
     fprintf_filtered (gdb_stdlog, "qf->print_stats (%s, %d)\n",
 		      objfile_debug_name (this), print_bcache);
 
-  if (qf != nullptr)
-    qf->print_stats (this, print_bcache);
+  for (const auto &iter : qf)
+    iter->print_stats (this, print_bcache);
 }
 
 void
@@ -191,8 +207,8 @@ objfile::dump ()
     fprintf_filtered (gdb_stdlog, "qf->dump (%s)\n",
 		      objfile_debug_name (this));
 
-  if (qf != nullptr)
-    qf->dump (this);
+  for (const auto &iter : qf)
+    iter->dump (this);
 }
 
 void
@@ -203,8 +219,8 @@ objfile::expand_symtabs_for_function (const char *func_name)
 		      "qf->expand_symtabs_for_function (%s, \"%s\")\n",
 		      objfile_debug_name (this), func_name);
 
-  if (qf != nullptr)
-    qf->expand_symtabs_for_function (this, func_name);
+  for (const auto &iter : qf)
+    iter->expand_symtabs_for_function (this, func_name);
 }
 
 void
@@ -214,8 +230,8 @@ objfile::expand_all_symtabs ()
     fprintf_filtered (gdb_stdlog, "qf->expand_all_symtabs (%s)\n",
 		      objfile_debug_name (this));
 
-  if (qf != nullptr)
-    qf->expand_all_symtabs (this);
+  for (const auto &iter : qf)
+    iter->expand_all_symtabs (this);
 }
 
 void
@@ -226,8 +242,8 @@ objfile::expand_symtabs_with_fullname (const char *fullname)
 		      "qf->expand_symtabs_with_fullname (%s, \"%s\")\n",
 		      objfile_debug_name (this), fullname);
 
-  if (qf != nullptr)
-    qf->expand_symtabs_with_fullname (this, fullname);
+  for (const auto &iter : qf)
+    iter->expand_symtabs_with_fullname (this, fullname);
 }
 
 void
@@ -244,9 +260,9 @@ objfile::map_matching_symbols
 		      domain_name (domain), global,
 		      host_address_to_string (ordered_compare));
 
-  if (qf != nullptr)
-    qf->map_matching_symbols (this, name, domain, global,
-			      callback, ordered_compare);
+  for (const auto &iter : qf)
+    iter->map_matching_symbols (this, name, domain, global,
+				callback, ordered_compare);
 }
 
 void
@@ -266,9 +282,9 @@ objfile::expand_symtabs_matching
 		      host_address_to_string (&expansion_notify),
 		      search_domain_name (kind));
 
-  if (qf != nullptr)
-    qf->expand_symtabs_matching (this, file_matcher, lookup_name,
-				 symbol_matcher, expansion_notify, kind);
+  for (const auto &iter : qf)
+    iter->expand_symtabs_matching (this, file_matcher, lookup_name,
+				   symbol_matcher, expansion_notify, kind);
 }
 
 struct compunit_symtab *
@@ -288,9 +304,13 @@ objfile::find_pc_sect_compunit_symtab (struct bound_minimal_symbol msymbol,
 		      host_address_to_string (section),
 		      warn_if_readin);
 
-  if (qf != nullptr)
-    retval = qf->find_pc_sect_compunit_symtab (this, msymbol, pc, section,
-					       warn_if_readin);
+  for (const auto &iter : qf)
+    {
+      retval = iter->find_pc_sect_compunit_symtab (this, msymbol, pc, section,
+						   warn_if_readin);
+      if (retval != nullptr)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog,
@@ -314,8 +334,8 @@ objfile::map_symbol_filenames (symbol_filename_ftype *fun, void *data,
 		      host_address_to_string (data),
 		      need_fullname);
 
-  if (qf != nullptr)
-    qf->map_symbol_filenames (this, fun, data, need_fullname);
+  for (const auto &iter : qf)
+    iter->map_symbol_filenames (this, fun, data, need_fullname);
 }
 
 struct compunit_symtab *
@@ -328,8 +348,12 @@ objfile::find_compunit_symtab_by_address (CORE_ADDR address)
 		      hex_string (address));
 
   struct compunit_symtab *result = NULL;
-  if (qf != nullptr)
-    result = qf->find_compunit_symtab_by_address (this, address);
+  for (const auto &iter : qf)
+    {
+      result = iter->find_compunit_symtab_by_address (this, address);
+      if (result != nullptr)
+	break;
+    }
 
   if (debug_symfile)
     fprintf_filtered (gdb_stdlog,
@@ -347,12 +371,15 @@ objfile::lookup_global_symbol_language (const char *name,
 					bool *symbol_found_p)
 {
   enum language result = language_unknown;
+  *symbol_found_p = false;
 
-  if (qf != nullptr)
-    result = qf->lookup_global_symbol_language (this, name, domain,
-						symbol_found_p);
-  else
-    *symbol_found_p = false;
+  for (const auto &iter : qf)
+    {
+      result = iter->lookup_global_symbol_language (this, name, domain,
+						    symbol_found_p);
+      if (*symbol_found_p)
+	break;
+    }
 
   return result;
 }
@@ -364,17 +391,23 @@ objfile::require_partial_symbols (bool verbose)
     {
       flags |= OBJF_PSYMTABS_READ;
 
-      if (qf->can_lazily_read_symbols ())
+      bool printed = false;
+      for (const auto &iter : qf)
 	{
-	  if (verbose)
-	    printf_filtered (_("Reading symbols from %s...\n"),
-			     objfile_name (this));
-	  qf->read_partial_symbols (this);
-
-	  if (verbose && !objfile_has_symbols (this))
-	    printf_filtered (_("(No debugging symbols found in %s)\n"),
-			     objfile_name (this));
+	  if (iter->can_lazily_read_symbols ())
+	    {
+	      if (verbose && !printed)
+		{
+		  printf_filtered (_("Reading symbols from %s...\n"),
+				   objfile_name (this));
+		  printed = true;
+		}
+	      iter->read_partial_symbols (this);
+	    }
 	}
+      if (printed && !objfile_has_symbols (this))
+	printf_filtered (_("(No debugging symbols found in %s)\n"),
+			 objfile_name (this));
     }
 }
 
diff --git a/gdb/symfile.c b/gdb/symfile.c
index d2ea04ed149..244565f8f47 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -903,7 +903,8 @@ syms_from_objfile_1 (struct objfile *objfile,
 
   objfile_set_sym_fns (objfile, find_sym_fns (objfile->obfd));
   objfile->reset_psymtabs ();
-  objfile->qf = make_psymbol_functions (objfile->partial_symtabs);
+  objfile->qf.clear ();
+  objfile->qf.push_front (make_psymbol_functions (objfile->partial_symtabs));
 
   if (objfile->sf == NULL)
     {
@@ -2553,7 +2554,9 @@ reread_symbols (void)
 	     start over.  PR symtab/15885  */
 	  objfile_set_sym_fns (objfile, find_sym_fns (objfile->obfd));
 	  objfile->reset_psymtabs ();
-	  objfile->qf = make_psymbol_functions (objfile->partial_symtabs);
+	  objfile->qf.clear ();
+	  objfile->qf.push_front
+	    (make_psymbol_functions (objfile->partial_symtabs));
 
 	  build_objfile_section_table (objfile);
 
-- 
2.26.2