Do not accidentally localize symbols when there is a hidden symbol in the same comdat group

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
In the testcase for PR (which I do not know how to turn in to a testuiste
version becuase it requires LTOed dynamic library) there is comdat group
with one hiddena and one global symbol.  At LTO we realize that hidden
symbol can be brought static, but at that time we also accidentally localize
the exported symbol.

Bootstrapped/regtested x86_64-linux, comitted. Martin also kindly tested that
it makes no difference for Firefox build.

Honza

	PR lto/69953 
	* ipa-visibility.c (non_local_p): Fix typos.
	(localize_node): When localizing symbol in same comdat group,
	dissolve the group only when we know external symbols are going
	to be privatized.
	(function_and_variable_visibility): Do not localize DECL_EXTERNAL.
Index: ipa-visibility.c
===================================================================
--- ipa-visibility.c	(revision 246895)
+++ ipa-visibility.c	(working copy)
@@ -90,8 +90,8 @@ static bool
 non_local_p (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
 {
   return !(node->only_called_directly_or_aliased_p ()
-	   /* i386 would need update to output thunk with locak calling
-	      ocnvetions.  */
+	   /* i386 would need update to output thunk with local calling
+	      convetions.  */
 	   && !node->thunk.thunk_p
 	   && node->definition
 	   && !DECL_EXTERNAL (node->decl)
@@ -153,7 +153,7 @@ comdat_can_be_unshared_p_1 (symtab_node
 /* COMDAT functions must be shared only if they have address taken,
    otherwise we can produce our own private implementation with
    -fwhole-program.  
-   Return true when turning COMDAT functoin static can not lead to wrong
+   Return true when turning COMDAT function static can not lead to wrong
    code when the resulting object links with a library defining same COMDAT.
 
    Virtual functions do have their addresses taken from the vtables,
@@ -537,6 +537,35 @@ localize_node (bool whole_program, symta
 {
   gcc_assert (whole_program || in_lto_p || !TREE_PUBLIC (node->decl));
 
+  /* It is possible that one comdat group contains both hidden and non-hidden
+     symbols.  In this case we can privatize all hidden symbol but we need
+     to keep non-hidden exported.  */
+  if (node->same_comdat_group
+      && node->resolution == LDPR_PREVAILING_DEF_IRONLY)
+    {
+      symtab_node *next;
+      for (next = node->same_comdat_group;
+	   next != node; next = next->same_comdat_group)
+	if (next->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP
+	    || next->resolution == LDPR_PREVAILING_DEF)
+	  break;
+      if (node != next)
+	{
+	  if (!node->transparent_alias)
+	    {
+	      node->resolution = LDPR_PREVAILING_DEF_IRONLY;
+	      node->make_decl_local ();
+	      if (!flag_incremental_link)
+	        node->unique_name |= true;
+	      return;
+	    }
+	}
+    }
+  /* For similar reason do not privatize whole comdat when seeing comdat
+     local.  Wait for non-comdat symbol to be privatized first.  */
+  if (node->comdat_local_p ())
+    return;
+
   if (node->same_comdat_group && TREE_PUBLIC (node->decl))
     {
       for (symtab_node *next = node->same_comdat_group;
@@ -765,7 +794,8 @@ function_and_variable_visibility (bool w
 	vnode->no_reorder = 1;
 
       if (!vnode->externally_visible
-	  && !vnode->transparent_alias)
+	  && !vnode->transparent_alias
+	  && !DECL_EXTERNAL (vnode->decl))
 	localize_node (whole_program, vnode);
 
       update_visibility_by_resolution_info (vnode);