Re: Move DECL_SECTION_NAME into symtab

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
this patch proceeds with the conversion of sections to symtab. It adds the
verifier I described in previous mail and fixes the fallout. It also moves
implicit_section flag from decl to cgraph.

Next step I would like to do is to add an hashtable dictionary of sections used
and move representation out of STRING_CST. This is wastes a lot of tree nodes
especially with LTO where we load a lot of duplicated comdats and then quickly
remove them. STRING_CSTs are not shared.

Sadly the final version of patch doesn't seem to help AIX issues. I am looking
into them now.

Honza

	* varasm.c (set_implicit_section): New function.
	(resolve_unique_section): Use it to set implicit section
	for aliases, too.
	(get_named_text_section): Use symtab_get_node (decl)->implicit_section
	(default_function_section): Likewise.
	(decl_binds_to_current_def_p): Constify argument.
	* varasm.h (decl_binds_to_current_def_p): Update prototype.
	* asan.c (asan_protect_global): Use symtab_get_node (decl)->implicit_section.
	* symtab.c (dump_symtab_base): Dump implicit sections.
	(verify_symtab_base): Verify sanity of sectoins and comdats.
	(symtab_resolve_alias): Alias share the section of its target.
	(set_section_1): New function.
	(symtab_node::set_section): Move here, recurse to aliases.
	(verify_symtab): Check for duplicated symtab lists.
	* tree-core.h (implicit_section_name_p): Remove.
	* tree-vect-data-refs.c: Include varasm.h.
	(vect_can_force_dr_alignment_p): Fix conditional on when
	decl bints to current definition; use
	symtab_get_node (decl)->implicit_section.
	* cgraph.c (cgraph_make_node_local_1): Fix section set.
	* cgraph.h (struct symtab_node): Add implicit_section.
	(set_section): Rename to ...
	(set_section_for_node): ... this one.
	(set_section): Declare.
	* tree.h (DECL_HAS_IMPLICIT_SECTION_NAME_P): Remove.
	* lto-cgraph.c (lto_output_node, lto_output_varpool_node,
	input_overwrite_node, input_varpool_node): Stream implicit_section.
	* ipa.c (symtab_remove_unreachable_nodes): Do not check symtab before
	removal; it will fail in LTO.
	
	* vtable-class-hierarchy.c: Use symtab_get_node (var_decl)->implicit_section.
	* optimize.c (cdtor_comdat_group): Fix handling of aliases.
	(maybe_clone_body): Move symbol across comdat groups.
	* method.c (use_thunk): Copy implicit section flag.

	* go/go-gcc.cc (Gcc_backend::global_variable_set_init): Use
	symtab_get_node(var_decl)->implicit_section.

	* lto.c (read_cgraph_and_symbols): Remove unreachable symbols.
	(do_whole_program_analysis): Use verify_symtab.
Index: asan.c
===================================================================
--- asan.c	(revision 211364)
+++ asan.c	(working copy)
@@ -1289,7 +1289,7 @@ asan_protect_global (tree decl)
 	 to be an array of such vars, putting padding in there
 	 breaks this assumption.  */
       || (DECL_SECTION_NAME (decl) != NULL_TREE
-	  && !DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+	  && !symtab_get_node (decl)->implicit_section)
       || DECL_SIZE (decl) == 0
       || ASAN_RED_ZONE_SIZE * BITS_PER_UNIT > MAX_OFILE_ALIGNMENT
       || !valid_constant_size_p (DECL_SIZE_UNIT (decl))
Index: cp/optimize.c
===================================================================
--- cp/optimize.c	(revision 211364)
+++ cp/optimize.c	(working copy)
@@ -191,7 +191,7 @@ cdtor_comdat_group (tree complete, tree
 	diff_seen = true;
       }
   grp_name[idx] = '\0';
-  gcc_assert (diff_seen);
+  gcc_assert (diff_seen || symtab_get_node (complete)->alias);
   return get_identifier (grp_name);
 }
 
@@ -553,6 +553,8 @@ maybe_clone_body (tree fn)
 		 *[CD][12]*.  */
 	      comdat_group = cdtor_comdat_group (fns[1], fns[0]);
 	      cgraph_get_create_node (fns[0])->set_comdat_group (comdat_group);
+	      if (symtab_get_node (clone)->same_comdat_group)
+		symtab_remove_from_same_comdat_group (symtab_get_node (clone));
 	      symtab_add_to_same_comdat_group (symtab_get_node (clone),
 					       symtab_get_node (fns[0]));
 	    }
Index: cp/vtable-class-hierarchy.c
===================================================================
--- cp/vtable-class-hierarchy.c	(revision 211364)
+++ cp/vtable-class-hierarchy.c	(working copy)
@@ -1249,7 +1249,7 @@ vtable_find_or_create_map_decl (tree bas
 
       set_decl_section_name (var_decl, build_string (strlen (".vtable_map_vars"),
                                                      ".vtable_map_vars"));
-      DECL_HAS_IMPLICIT_SECTION_NAME_P (var_decl) = true;
+      symtab_get_node (var_decl)->implicit_section = true;
       DECL_INITIAL (var_decl) = initial_value;
 
       comdat_linkage (var_decl);
Index: cp/method.c
===================================================================
--- cp/method.c	(revision 211364)
+++ cp/method.c	(working copy)
@@ -356,14 +356,27 @@ use_thunk (tree thunk_fndecl, bool emit_
   if (TARGET_USE_LOCAL_THUNK_ALIAS_P (function)
       && targetm_common.have_named_sections)
     {
-      resolve_unique_section (function, 0, flag_function_sections);
+      tree fn = function;
+      struct symtab_node *symbol;
 
-      if (DECL_SECTION_NAME (function) != NULL && DECL_ONE_ONLY (function))
+      if ((symbol = symtab_get_node (function))
+	  && symbol->alias)
+	{
+	  if (symbol->analyzed)
+	    fn = symtab_alias_ultimate_target (symtab_get_node (function))->decl;
+	  else
+	    fn = symtab_get_node (function)->alias_target;
+	}
+      resolve_unique_section (fn, 0, flag_function_sections);
+
+      if (DECL_SECTION_NAME (fn) != NULL && DECL_ONE_ONLY (fn))
 	{
 	  resolve_unique_section (thunk_fndecl, 0, flag_function_sections);
 
 	  /* Output the thunk into the same section as function.  */
-	  set_decl_section_name (thunk_fndecl, DECL_SECTION_NAME (function));
+	  set_decl_section_name (thunk_fndecl, DECL_SECTION_NAME (fn));
+	  symtab_get_node (thunk_fndecl)->implicit_section
+	    = symtab_get_node (fn)->implicit_section;
 	}
     }
 
Index: lto/lto.c
===================================================================
--- lto/lto.c	(revision 211364)
+++ lto/lto.c	(working copy)
@@ -3090,6 +3090,7 @@ read_cgraph_and_symbols (unsigned nfiles
       dump_symtab (cgraph_dump_file);
     }
   lto_symtab_merge_symbols ();
+   /* Removal of unreacable symbols is needed to make verify_symtab to pass;
+      we are still having duplicated comdat groups containing local statics.
+      We could also just remove them while merging.  */
+  symtab_remove_unreachable_nodes (false, dump_file);
   ggc_collect ();
   cgraph_state = CGRAPH_STATE_IPA_SSA;
 
@@ -3261,7 +3262,7 @@ do_whole_program_analysis (void)
       dump_symtab (cgraph_dump_file);
     }
 #ifdef ENABLE_CHECKING
-  verify_cgraph ();
+  verify_symtab ();
 #endif
   bitmap_obstack_release (NULL);
 
Index: go/go-gcc.cc
===================================================================
--- go/go-gcc.cc	(revision 211364)
+++ go/go-gcc.cc	(working copy)
@@ -2374,7 +2374,8 @@ Gcc_backend::global_variable_set_init(Bv
 
   // If this variable goes in a unique section, it may need to go into
   // a different one now that DECL_INITIAL is set.
-  if (DECL_HAS_IMPLICIT_SECTION_NAME_P (var_decl))
+  if (symtab_get_node(var_decl)
+      && symtab_get_node(var_decl)->implicit_section)
     {
       set_decl_section_name (var_decl, NULL);
       resolve_unique_section (var_decl,
Index: ipa.c
===================================================================
--- ipa.c	(revision 211364)
+++ ipa.c	(working copy)
@@ -281,9 +281,6 @@ symtab_remove_unreachable_nodes (bool be
   struct pointer_set_t *reachable_call_targets = pointer_set_create ();
 
   timevar_push (TV_IPA_UNREACHABLE);
-#ifdef ENABLE_CHECKING
-  verify_symtab ();
-#endif
   if (optimize && flag_devirtualize)
     build_type_inheritance_graph ();
   if (file)
Index: tree-vect-data-refs.c
===================================================================
--- tree-vect-data-refs.c	(revision 211364)
+++ tree-vect-data-refs.c	(working copy)
@@ -5215,7 +5215,7 @@ vect_can_force_dr_alignment_p (const_tre
      software projects.  */
   if (TREE_STATIC (decl) 
       && DECL_SECTION_NAME (decl) != NULL_TREE
-      && !DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+      && !symtab_get_node (decl)->implicit_section)
     return false;
 
   if (TREE_STATIC (decl))
Index: varasm.c
===================================================================
--- varasm.c	(revision 211364)
+++ varasm.c	(working copy)
@@ -418,6 +418,15 @@ get_named_section (tree decl, const char
   return get_section (name, flags, decl);
 }
 
+/* Worker for resolve_unique_section.  */
+
+static bool
+set_implicit_section (struct symtab_node *n, void *data ATTRIBUTE_UNUSED)
+{
+  n->implicit_section = true;
+  return false;
+}
+
 /* If required, set DECL_SECTION_NAME to a unique name.  */
 
 void
@@ -430,7 +439,9 @@ resolve_unique_section (tree decl, int r
 	  || DECL_COMDAT_GROUP (decl)))
     {
       targetm.asm_out.unique_section (decl, reloc);
-      DECL_HAS_IMPLICIT_SECTION_NAME_P (decl) = true;
+      if (DECL_SECTION_NAME (decl))
+        symtab_for_node_and_aliases (symtab_get_node (decl),
+				     set_implicit_section, NULL, true);
     }
 }
 
@@ -510,7 +521,7 @@ get_named_text_section (tree decl,
 	  buffer = ACONCAT ((stripped_name, named_section_suffix, NULL));
 	  return get_named_section (decl, buffer, 0);
 	}
-      else if (DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+      else if (symtab_get_node (decl)->implicit_section)
 	{
 	  const char *name;
 
@@ -539,8 +550,7 @@ default_function_section (tree decl, enu
   /* Old GNU linkers have buggy --gc-section support, which sometimes
      results in .gcc_except_table* sections being garbage collected.  */
   if (decl
-      && DECL_SECTION_NAME (decl)
-      && DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+      && symtab_get_node (decl)->implicit_section)
     return NULL;
 #endif
 
@@ -6764,7 +6774,7 @@ default_binds_local_p_1 (const_tree exp,
    definition from different object file) and when resolution info is available
    we simply use the knowledge passed to us by linker plugin.  */
 bool
-decl_binds_to_current_def_p (tree decl)
+decl_binds_to_current_def_p (const_tree decl)
 {
   gcc_assert (DECL_P (decl));
   if (!targetm.binds_local_p (decl))
Index: varasm.h
===================================================================
--- varasm.h	(revision 211364)
+++ varasm.h	(working copy)
@@ -32,7 +32,7 @@ extern void notice_global_symbol (tree);
 extern void set_user_assembler_name (tree, const char *);
 extern void process_pending_assemble_externals (void);
 extern bool decl_replaceable_p (tree);
-extern bool decl_binds_to_current_def_p (tree);
+extern bool decl_binds_to_current_def_p (const_tree);
 extern enum tls_model decl_default_tls_model (const_tree);
 
 /* Declare DECL to be a weak symbol.  */
Index: tree-core.h
===================================================================
--- tree-core.h	(revision 211395)
+++ tree-core.h	(working copy)
@@ -1452,8 +1452,6 @@ struct GTY(()) tree_decl_with_vis {
  unsigned dllimport_flag : 1;
  /* Don't belong to VAR_DECL exclusively.  */
  unsigned weak_flag : 1;
- /* When SECTION_NAME is implied by -ffunction-section.  */
- unsigned implicit_section_name_p : 1;
 
  unsigned seen_in_bind_expr : 1;
  unsigned comdat_flag : 1;
@@ -1472,7 +1470,7 @@ struct GTY(()) tree_decl_with_vis {
  unsigned cxx_destructor : 1;
  /* Belong to FUNCTION_DECL exclusively.  */
  unsigned final : 1;
- /* 11 unused bits. */
+ /* 12 unused bits. */
 };
 
 struct GTY(()) tree_var_decl {
Index: symtab.c
===================================================================
--- symtab.c	(revision 211364)
+++ symtab.c	(working copy)
@@ -565,7 +565,9 @@ dump_symtab_base (FILE *f, symtab_node *
     fprintf (f, " one_only");
   if (node->get_section ())
     fprintf (f, " section:%s",
-	     TREE_STRING_POINTER (node->get_section ()));
+	     node->get_section ());
+  if (node->implicit_section)
+    fprintf (f," (implicit_section)");
   if (DECL_VISIBILITY_SPECIFIED (node->decl))
     fprintf (f, " visibility_specified");
   if (DECL_VISIBILITY (node->decl))
@@ -791,6 +793,7 @@ verify_symtab_base (symtab_node *node)
 	{
 	  struct ipa_ref_list *refs = &node->ref_list;
 	  struct ipa_ref *ref;
+
 	  for (int i = 0; ipa_ref_list_referring_iterate (refs, i, ref); ++i)
 	    {
 	      if (!symtab_in_same_comdat_p (ref->referring, node))
@@ -803,6 +806,38 @@ verify_symtab_base (symtab_node *node)
 	    }
 	}
     }
+  if (node->implicit_section && !node->get_section ())
+    {
+      error ("implicit_section flag is set but section isn't");
+      error_found = true;
+    }
+  if (node->get_section () && node->get_comdat_group ()
+      && !node->implicit_section)
+    {
+      error ("Both section and comdat group is set");
+      error_found = true;
+    }
+  /* TODO: Add string table for sections, so we do not keep holding duplicated
+     strings.  */
+  if (node->alias && node->definition
+      && node->get_section () != symtab_alias_target (node)->get_section ()
+      && (!node->get_section()
+	  || !symtab_alias_target (node)->get_section ()
+	  || strcmp (node->get_section(),
+		     symtab_alias_target (node)->get_section ())))
+    {
+      error ("Alias and target's section differs");
+      dump_symtab_node (stderr, symtab_alias_target (node));
+      error_found = true;
+    }
+  if (node->alias && node->definition
+      && node->get_comdat_group () != symtab_alias_target (node)->get_comdat_group ())
+    {
+      error ("Alias and target's comdat groups differs");
+      dump_symtab_node (stderr, symtab_alias_target (node));
+      error_found = true;
+    }
+
   return error_found;
 }
 
@@ -832,8 +867,30 @@ DEBUG_FUNCTION void
 verify_symtab (void)
 {
   symtab_node *node;
+  pointer_map<symtab_node *> comdat_head_map;
+
   FOR_EACH_SYMBOL (node)
-   verify_symtab_node (node);
+    {
+      verify_symtab_node (node);
+      if (node->get_comdat_group ())
+	{
+	  symtab_node **entry, *s;
+	  bool existed;
+
+	  entry = comdat_head_map.insert (node->get_comdat_group (), &existed);
+	  if (!existed)
+	    *entry = node;
+	  else
+	    for (s = (*entry)->same_comdat_group; s != NULL && s != node; s = s->same_comdat_group)
+	      if (!s || s == *entry)
+		{
+		  error ("Two symbols with same comdat_group are not linked by the same_comdat_group list.");
+		  dump_symtab_node (stderr, *entry);
+		  dump_symtab_node (stderr, s);
+		  internal_error ("verify_symtab failed");
+		}
+	}
+    }
 }
 
 /* Return true when RESOLUTION indicate that linker will use
@@ -1024,6 +1081,33 @@ fixup_same_cpp_alias_visibility (symtab_
   node->externally_visible = target->externally_visible;
 }
 
+/* Worker for set_section.  */
+
+static bool
+set_section_1 (struct symtab_node *n, void *s)
+{
+  n->set_section_for_node ((tree)s);
+  return false;
+}
+
+/* Set section of symbol and its aliases.  */
+
+void
+symtab_node::set_section (tree section)
+{
+  gcc_assert (!this->alias);
+  symtab_for_node_and_aliases (this, set_section_1, section, true);
+}
+
+/* Worker for symtab_resolve_alias.  */
+
+static bool
+set_implicit_section (struct symtab_node *n, void *data ATTRIBUTE_UNUSED)
+{
+  n->implicit_section = true;
+  return false;
+}
+
 /* Add reference recording that NODE is alias of TARGET.
    The function can fail in the case of aliasing cycles; in this case
    it returns false.  */
@@ -1058,6 +1142,25 @@ symtab_resolve_alias (symtab_node *node,
   node->analyzed = true;
   ipa_record_reference (node, target, IPA_REF_ALIAS, NULL);
 
+  /* Add alias into the comdat group of its target unless it is already there.  */
+  if (node->same_comdat_group)
+    symtab_remove_from_same_comdat_group (node);
+  node->set_comdat_group (NULL);
+  if (target->get_comdat_group ())
+    symtab_add_to_same_comdat_group (node, target);
+
+  if ((node->get_section () != target->get_section ()
+       || target->get_comdat_group ())
+      && node->get_section () && !node->implicit_section)
+    {
+      error ("section of alias %q+D must match section of its target",
+	     node->decl);
+    }
+  symtab_for_node_and_aliases (node, set_section_1, target->get_section_name (), true);
+  if (target->implicit_section)
+    symtab_for_node_and_aliases (node,
+				 set_implicit_section, NULL, true);
+
   /* Alias targets become redundant after alias is resolved into an reference.
      We do not want to keep it around or we would have to mind updating them
      when renaming symbols.  */
Index: lto-cgraph.c
===================================================================
--- lto-cgraph.c	(revision 211364)
+++ lto-cgraph.c	(working copy)
@@ -501,10 +501,8 @@ lto_output_node (struct lto_simple_outpu
       streamer_write_hwi_stream (ob->main_stream, ref);
     }
 
-  group = node->get_section ();
-  if (group)
-    section = TREE_STRING_POINTER (group);
-  else
+  section = node->get_section ();
+  if (!section)
     section = "";
   lto_output_data_stream (ob->main_stream, section, strlen (section) + 1);
 
@@ -521,6 +519,7 @@ lto_output_node (struct lto_simple_outpu
   bp_pack_value (&bp, node->forced_by_abi, 1);
   bp_pack_value (&bp, node->unique_name, 1);
   bp_pack_value (&bp, node->body_removed, 1);
+  bp_pack_value (&bp, node->implicit_section, 1);
   bp_pack_value (&bp, node->address_taken, 1);
   bp_pack_value (&bp, tag == LTO_symtab_analyzed_node
 		 && symtab_get_symbol_partitioning_class (node) == SYMBOL_PARTITION
@@ -585,6 +584,7 @@ lto_output_varpool_node (struct lto_simp
   bp_pack_value (&bp, node->forced_by_abi, 1);
   bp_pack_value (&bp, node->unique_name, 1);
   bp_pack_value (&bp, node->body_removed, 1);
+  bp_pack_value (&bp, node->implicit_section, 1);
   bp_pack_value (&bp, node->writeonly, 1);
   bp_pack_value (&bp, node->definition, 1);
   alias_p = node->alias && (!boundary_p || node->weakref);
@@ -631,10 +631,8 @@ lto_output_varpool_node (struct lto_simp
       streamer_write_hwi_stream (ob->main_stream, ref);
     }
 
-  group = node->get_section ();
-  if (group)
-    section = TREE_STRING_POINTER (group);
-  else
+  section = node->get_section ();
+  if (!section)
     section = "";
   lto_output_data_stream (ob->main_stream, section, strlen (section) + 1);
 
@@ -1054,6 +1052,7 @@ input_overwrite_node (struct lto_file_de
   node->forced_by_abi = bp_unpack_value (bp, 1);
   node->unique_name = bp_unpack_value (bp, 1);
   node->body_removed = bp_unpack_value (bp, 1);
+  node->implicit_section = bp_unpack_value (bp, 1);
   node->address_taken = bp_unpack_value (bp, 1);
   node->used_from_other_partition = bp_unpack_value (bp, 1);
   node->lowered = bp_unpack_value (bp, 1);
@@ -1194,7 +1193,7 @@ input_node (struct lto_file_decl_data *f
   else
     node->same_comdat_group = (symtab_node *) (intptr_t) LCC_NOT_FOUND;
   if (section)
-    node->set_section (section);
+    node->set_section_for_node (section);
 
   if (node->thunk.thunk_p)
     {
@@ -1251,6 +1250,7 @@ input_varpool_node (struct lto_file_decl
   node->forced_by_abi = bp_unpack_value (&bp, 1);
   node->unique_name = bp_unpack_value (&bp, 1);
   node->body_removed = bp_unpack_value (&bp, 1);
+  node->implicit_section = bp_unpack_value (&bp, 1);
   node->writeonly = bp_unpack_value (&bp, 1);
   node->definition = bp_unpack_value (&bp, 1);
   node->alias = bp_unpack_value (&bp, 1);
@@ -1277,7 +1277,7 @@ input_varpool_node (struct lto_file_decl
     node->same_comdat_group = (symtab_node *) (intptr_t) LCC_NOT_FOUND;
   section = read_string_cst (ib);
   if (section)
-    node->set_section (section);
+    node->set_section_for_node (section);
   node->resolution = streamer_read_enum (ib, ld_plugin_symbol_resolution,
 					        LDPR_NUM_KNOWN);
   gcc_assert (flag_ltrans
Index: tree.c
===================================================================
--- tree.c	(revision 211364)
+++ tree.c	(working copy)
@@ -634,7 +634,7 @@ decl_section_name (const_tree node)
   struct symtab_node *snode = symtab_get_node (node);
   if (!snode)
     return NULL;
-  return snode->get_section ();
+  return snode->get_section_name ();
 }
 
 /* Set section section name of NODE to VALUE (that is expected to
Index: tree.h
===================================================================
--- tree.h	(revision 211364)
+++ tree.h	(working copy)
@@ -2399,11 +2399,6 @@ extern void decl_value_expr_insert (tree
 #define DECL_HAS_INIT_PRIORITY_P(NODE) \
   (VAR_DECL_CHECK (NODE)->decl_with_vis.init_priority_p)
 
-/* Specify whether the section name was set by user or by
-   compiler via -ffunction-sections.  */
-#define DECL_HAS_IMPLICIT_SECTION_NAME_P(NODE) \
-  (DECL_WITH_VIS_CHECK (NODE)->decl_with_vis.implicit_section_name_p)
-
 extern tree decl_debug_expr_lookup (tree);
 extern void decl_debug_expr_insert (tree, tree);
 
Index: ipa-visibility.c
===================================================================
--- ipa-visibility.c	(revision 211364)
+++ ipa-visibility.c	(working copy)
@@ -512,7 +512,8 @@ function_and_variable_visibility (bool w
 		     next = next->same_comdat_group)
 		{
 		  next->set_comdat_group (NULL);
-		  next->set_section (NULL);
+		  if (!next->alias)
+		    next->set_section (NULL);
 		  symtab_make_decl_local (next->decl);
 		  next->unique_name = ((next->resolution == LDPR_PREVAILING_DEF_IRONLY
 					|| next->unique_name
@@ -527,7 +528,7 @@ function_and_variable_visibility (bool w
 	    }
 	  if (TREE_PUBLIC (node->decl))
 	    node->set_comdat_group (NULL);
-	  if (DECL_COMDAT (node->decl))
+	  if (DECL_COMDAT (node->decl) && !node->alias)
 	    node->set_section (NULL);
 	  symtab_make_decl_local (node->decl);
 	}
@@ -646,7 +647,8 @@ function_and_variable_visibility (bool w
 		     next = next->same_comdat_group)
 		{
 		  next->set_comdat_group (NULL);
-		  next->set_section (NULL);
+		  if (!next->alias)
+		    next->set_section (NULL);
 		  symtab_make_decl_local (next->decl);
 		  next->unique_name = ((next->resolution == LDPR_PREVAILING_DEF_IRONLY
 					|| next->unique_name
@@ -657,7 +659,7 @@ function_and_variable_visibility (bool w
 	    }
 	  if (TREE_PUBLIC (vnode->decl))
 	    vnode->set_comdat_group (NULL);
-	  if (DECL_COMDAT (vnode->decl))
+	  if (DECL_COMDAT (vnode->decl) && !vnode->alias)
 	    vnode->set_section (NULL);
 	  symtab_make_decl_local (vnode->decl);
 	  vnode->resolution = LDPR_PREVAILING_DEF_IRONLY;
Index: cgraph.c
===================================================================
--- cgraph.c	(revision 211364)
+++ cgraph.c	(working copy)
@@ -2264,7 +2264,7 @@ cgraph_make_node_local_1 (struct cgraph_
       node->externally_visible = false;
       node->forced_by_abi = false;
       node->local.local = true;
-      node->set_comdat_group (NULL);
+      node->set_section (NULL);
       node->unique_name = (node->resolution == LDPR_PREVAILING_DEF_IRONLY
 				  || node->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP);
       node->resolution = LDPR_PREVAILING_DEF_IRONLY;
Index: cgraph.h
===================================================================
--- cgraph.h	(revision 211364)
+++ cgraph.h	(working copy)
@@ -93,6 +93,9 @@ public:
   unsigned forced_by_abi : 1;
   /* True when the name is known to be unique and thus it does not need mangling.  */
   unsigned unique_name : 1;
+  /* Specify whether the section was set by user or by
+     compiler via -ffunction-sections.  */
+  unsigned implicit_section : 1;
   /* True when body and other characteristics have been removed by
      symtab_remove_unreachable_nodes. */
   unsigned body_removed : 1;
@@ -162,17 +165,29 @@ public:
       comdat_group_ = group;
     }
 
-  /* Return section.  */
-  tree get_section ()
+  /* Return section as STRING_CST.  */
+  tree get_section_name ()
     {
       return section_;
     }
 
-  /* Set section.  */
-  void set_section (tree section)
+  /* Return section as string.  */
+  const char * get_section ()
+    {
+      if (!section_)
+	return NULL;
+      return TREE_STRING_POINTER (section_);
+    }
+
+  /* Set section, do not recurse into aliases.
+     When one wants to change section of symbol and its aliases,
+     use set_section  */
+  void set_section_for_node (tree section)
     {
       gcc_checking_assert (!section || TREE_CODE (section) == STRING_CST);
       section_ = section;
+      if (!section)
+	implicit_section = false;
     }
 
   /* Vectors of referring and referenced entities.  */
@@ -193,6 +208,9 @@ public:
 
   /* Section name. Again can be private, if allowed.  */
   tree section_;
+
+  /* Set section for symbol and its aliases.  */
+  void set_section (tree section);
 };
 
 enum availability