re PR middle-end/51663 (Desirable/undesirable elimination of unused variables &…

re PR middle-end/51663 (Desirable/undesirable elimination of unused variables & functions at -O0, -O0 -flto and -O0 -fwhole-program)

	PR lto/51663
	* varpool.c (varpool_finalize_decl): Handle toplevel_reorder here.
	(decide_is_variable_needed): Do not handle toplevel reorder here.
	* cgraph.h (varpool_can_remove_if_no_refs): Likewise.
	* ipa.c (cgraph_remove_unreachable_nodes): Remove unreachable vars
	even at -O0.

From-SVN: r185777

gcc/ChangeLog

+2012-03-24  Jan Hubicka  <jh@suse.cz>
+
+	PR lto/51663
+	* varpool.c (varpool_finalize_decl): Handle toplevel_reorder here.
+	(decide_is_variable_needed): Do not handle toplevel reorder here.
+	* cgraph.h (varpool_can_remove_if_no_refs): Likewise.
+	* ipa.c (cgraph_remove_unreachable_nodes): Remove unreachable vars
+	even at -O0.
+
 2012-03-24  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* expr.c (optimize_bitfield_assignment_op) <BIT_IOR_EXPR>: Use str_mode

gcc/cgraph.h

@@ -947,8 +947,6 @@ static inline bool
 varpool_can_remove_if_no_refs (struct varpool_node *node)
 {
   return (!node->force_output && !node->used_from_other_partition
-	  && (flag_toplevel_reorder || DECL_COMDAT (node->decl)
-	      || DECL_ARTIFICIAL (node->decl))
   	  && (DECL_COMDAT (node->decl) || !node->externally_visible));
 }
 

gcc/ipa.c

@@ -419,11 +419,6 @@ cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
   if (file)
     fprintf (file, "\n");
 
-  /* We must release unused extern inlines or sanity checking will fail.  Rest of transformations
-     are undesirable at -O0 since we do not want to remove anything.  */
-  if (!optimize)
-    return changed;
-
   if (file)
     fprintf (file, "Reclaiming variables:");
   for (vnode = varpool_nodes; vnode; vnode = vnext)
@@ -463,6 +458,10 @@ cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
   if (file)
     fprintf (file, "\n");
 
+  /* Rest of transformations are undesirable at -O0.  */
+  if (!optimize)
+    return changed;
+
 #ifdef ENABLE_CHECKING
   verify_cgraph ();
 #endif

gcc/varpool.c

@@ -334,10 +334,6 @@ decide_is_variable_needed (struct varpool_node *node, tree decl)
       && !DECL_EXTERNAL (decl))
     return true;
 
-  /* When not reordering top level variables, we have to assume that
-     we are going to keep everything.  */
-  if (!flag_toplevel_reorder)
-    return true;
   return false;
 }
 
@@ -405,7 +401,11 @@ varpool_finalize_decl (tree decl)
   if (node->needed)
     varpool_enqueue_needed_node (node);
   node->finalized = true;
-  if (TREE_THIS_VOLATILE (decl) || DECL_PRESERVE_P (decl))
+  if (TREE_THIS_VOLATILE (decl) || DECL_PRESERVE_P (decl)
+      /* Traditionally we do not eliminate static variables when not
+	 optimizing and when not doing toplevel reoder.  */
+      || (!flag_toplevel_reorder && !DECL_COMDAT (node->decl)
+	  && !DECL_ARTIFICIAL (node->decl)))
     node->force_output = true;
 
   if (decide_is_variable_needed (node, decl))