cgraph.c (cgraph_node::can_remove_if_no_direct_calls_p): Rewrite for correct comdat handling.

* cgraph.c (cgraph_node::can_remove_if_no_direct_calls_p): Rewrite
	for correct comdat handling.
	(cgraph_node::will_be_removed_from_program_if_no_direct_calls_p):
	Likewise.
	* cgraph.h (call_for_symbol_and_aliases): Fix formating.
	(used_from_object_file_p_worker): Remove.
	(cgraph_node::only_called_directly_or_alised): Add
	used_from_object_file_p.
	* ipa-inline-analysis.c (growth_likely_positive): Optimie.
	* ipa-inline-transform.c (can_remove_node_now_p_1): Use
	can_remove_if_no_direct_calls_and_refs_p.

From-SVN: r221193

gcc/ChangeLog

@@ -1,3 +1,17 @@
+2015-03-03  Jan Hubicka  <hubicka@ucw.cz>
+
+	* cgraph.c (cgraph_node::can_remove_if_no_direct_calls_p): Rewrite
+	for correct comdat handling.
+	(cgraph_node::will_be_removed_from_program_if_no_direct_calls_p):
+	Likewise.
+	* cgraph.h (call_for_symbol_and_aliases): Fix formating.
+	(used_from_object_file_p_worker): Remove.
+	(cgraph_node::only_called_directly_or_alised): Add
+	used_from_object_file_p.
+	* ipa-inline-analysis.c (growth_likely_positive): Optimie.
+	* ipa-inline-transform.c (can_remove_node_now_p_1): Use
+	can_remove_if_no_direct_calls_and_refs_p.
+
 2015-03-04  Nick Clifton  <nickc@redhat.com>
 
 	* config/rl78/rl78.h (enum reg_class): Remove real registers from

gcc/cgraph.c

@@ -2411,13 +2411,18 @@ nonremovable_p (cgraph_node *node, void *)
   return !node->can_remove_if_no_direct_calls_and_refs_p ();
 }
 
-/* Return true when function cgraph_node and its aliases can be removed from
+/* Return true if whole comdat group can be removed if there are no direct
-   callgraph if all direct calls are eliminated.  */
+   calls to THIS.  */
 
 bool
 cgraph_node::can_remove_if_no_direct_calls_p (void)
 {
-  /* Extern inlines can always go, we will use the external definition.  */
+  struct ipa_ref *ref;
+
+  /* For local symbols or non-comdat group it is the same as 
+     can_remove_if_no_direct_calls_p.  */
+  if (!externally_visible || !same_comdat_group)
+    {
       if (DECL_EXTERNAL (decl))
 	return true;
       if (address_taken)
@@ -2425,6 +2430,40 @@ cgraph_node::can_remove_if_no_direct_calls_p (void)
       return !call_for_symbol_and_aliases (nonremovable_p, NULL, true);
     }
 
+  /* Otheriwse check if we can remove the symbol itself and then verify
+     that only uses of the comdat groups are direct call to THIS
+     or its aliases.   */
+  if (!can_remove_if_no_direct_calls_and_refs_p ())
+    return false;
+
+  /* Check that all refs come from within the comdat group.  */
+  for (int i = 0; iterate_referring (i, ref); i++)
+    if (ref->referring->get_comdat_group () != get_comdat_group ())
+      return false;
+
+  struct cgraph_node *target = ultimate_alias_target ();
+  for (cgraph_node *next = dyn_cast<cgraph_node *> (same_comdat_group);
+       next != this; next = dyn_cast<cgraph_node *> (next->same_comdat_group))
+    {
+      if (!externally_visible)
+	continue;
+      if (!next->alias
+	  && !next->can_remove_if_no_direct_calls_and_refs_p ())
+	return false;
+
+      /* If we see different symbol than THIS, be sure to check calls.  */
+      if (next->ultimate_alias_target () != target)
+	for (cgraph_edge *e = next->callers; e; e = e->next_caller)
+	  if (e->caller->get_comdat_group () != get_comdat_group ())
+	    return false;
+
+      for (int i = 0; next->iterate_referring (i, ref); i++)
+	if (ref->referring->get_comdat_group () != get_comdat_group ())
+	  return false;
+    }
+  return true;
+}
+
 /* Return true when function cgraph_node can be expected to be removed
    from program when direct calls in this compilation unit are removed.
 
@@ -2442,20 +2481,48 @@ cgraph_node::can_remove_if_no_direct_calls_p (void)
 bool
 cgraph_node::will_be_removed_from_program_if_no_direct_calls_p (void)
 {
+  struct ipa_ref *ref;
   gcc_assert (!global.inlined_to);
-
-  if (call_for_symbol_and_aliases (used_from_object_file_p_worker,
-				   NULL, true))
-    return false;
-  if (!in_lto_p && !flag_whole_program)
-    return only_called_directly_p ();
-  else
-    {
   if (DECL_EXTERNAL (decl))
     return true;
-      return can_remove_if_no_direct_calls_p ();
+
+  if (!in_lto_p && !flag_whole_program)
+    {
+      /* If the symbol is in comdat group, we need to verify that whole comdat
+	 group becomes unreachable.  Technically we could skip references from
+	 within the group, too.  */
+      if (!only_called_directly_p ())
+	return false;
+      if (same_comdat_group && externally_visible)
+	{
+	  struct cgraph_node *target = ultimate_alias_target ();
+	  for (cgraph_node *next = dyn_cast<cgraph_node *> (same_comdat_group);
+	       next != this;
+	       next = dyn_cast<cgraph_node *> (next->same_comdat_group))
+	    {
+	      if (!externally_visible)
+		continue;
+	      if (!next->alias
+		  && !next->only_called_directly_p ())
+		return false;
+
+	      /* If we see different symbol than THIS,
+		 be sure to check calls.  */
+	      if (next->ultimate_alias_target () != target)
+		for (cgraph_edge *e = next->callers; e; e = e->next_caller)
+		  if (e->caller->get_comdat_group () != get_comdat_group ())
+		    return false;
+
+	      for (int i = 0; next->iterate_referring (i, ref); i++)
+		if (ref->referring->get_comdat_group () != get_comdat_group ())
+		  return false;
 	    }
 	}
+      return true;
+    }
+  else
+    return can_remove_if_no_direct_calls_p ();
+}
 
 
 /* Worker for cgraph_only_called_directly_p.  */

gcc/cgraph.h

@@ -1187,12 +1187,6 @@ public:
      returns cgraph_node::get (DECL).  */
   static cgraph_node * create_same_body_alias (tree alias, tree decl);
 
-  /* Worker for cgraph_can_remove_if_no_direct_calls_p.  */
-  static bool used_from_object_file_p_worker (cgraph_node *node, void *)
-  {
-    return node->used_from_object_file_p ();
-  }
-
   /* Verify whole cgraph structure.  */
   static void DEBUG_FUNCTION verify_cgraph_nodes (void);
 
@@ -2736,6 +2730,7 @@ cgraph_node::only_called_directly_or_aliased_p (void)
 	  && !DECL_VIRTUAL_P (decl)
 	  && !DECL_STATIC_CONSTRUCTOR (decl)
 	  && !DECL_STATIC_DESTRUCTOR (decl)
+	  && !used_from_object_file_p ()
 	  && !externally_visible);
 }
 

gcc/ipa-inline-analysis.c

@@ -4007,6 +4007,8 @@ growth_likely_positive (struct cgraph_node *node,
   struct cgraph_edge *e;
   gcc_checking_assert (edge_growth > 0);
 
+  if (DECL_EXTERNAL (node->decl))
+    return true;
   /* Unlike for functions called once, we play unsafe with
      COMDATs.  We can allow that since we know functions
      in consideration are small (and thus risk is small) and
@@ -4014,18 +4016,13 @@ growth_likely_positive (struct cgraph_node *node,
      functions may or may not disappear when eliminated from
      current unit. With good probability making aggressive
      choice in all units is going to make overall program
-     smaller.
+     smaller.  */
-
+  if (DECL_COMDAT (node->decl))
-     Consequently we ask cgraph_can_remove_if_no_direct_calls_p
+    {
-     instead of
+      if (!node->can_remove_if_no_direct_calls_p ())
-     cgraph_will_be_removed_from_program_if_no_direct_calls  */
-  if (DECL_EXTERNAL (node->decl)
-      || !node->can_remove_if_no_direct_calls_p ())
 	return true;
-
+    }
-  if (!node->will_be_removed_from_program_if_no_direct_calls_p ()
+  else if (!node->will_be_removed_from_program_if_no_direct_calls_p ())
-      && (!DECL_COMDAT (node->decl)
-	  || !node->can_remove_if_no_direct_calls_p ()))
     return true;
   max_callers = inline_summaries->get (node)->size * 4 / edge_growth + 2;
 

gcc/ipa-inline-transform.c

@@ -112,9 +112,12 @@ can_remove_node_now_p_1 (struct cgraph_node *node, struct cgraph_edge *e)
     }
   /* FIXME: When address is taken of DECL_EXTERNAL function we still
      can remove its offline copy, but we would need to keep unanalyzed node in
-     the callgraph so references can point to it.  */
+     the callgraph so references can point to it.
+
+     Also for comdat group we can ignore references inside a group as we
+     want to prove the group as a whole to be dead.  */
   return (!node->address_taken
-	  && node->can_remove_if_no_direct_calls_p ()
+	  && node->can_remove_if_no_direct_calls_and_refs_p ()
 	  /* Inlining might enable more devirtualizing, so we want to remove
 	     those only after all devirtualizable virtual calls are processed.
 	     Lacking may edges in callgraph we just preserve them post