2010-11-09 Richard Guenther <rguenther@suse.de>

	PR middle-end/46221
	* varasm.c (compute_visible_aliases): New function.
	(remove_unreachable_alias_pairs): Aliases make a target available
	even though we reclaimed the cgraph node.
	(finish_aliases_1): Likewise.
	* Makefile.in (varasm.o): Add pointer-set.h dependency.

	* gcc.target/i386/alias-1.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@166479 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 59 insertions, 1 deletions

diff --git a/gcc/varasm.c b/gcc/varasm.c
index fe60bb2397d..0c80c931fff 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -53,6 +53,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cfglayout.h"
 #include "basic-block.h"
 #include "tree-iterator.h"
+#include "pointer-set.h"
 
 #ifdef XCOFF_DEBUGGING_INFO
 #include "xcoffout.h"		/* Needed for external data
@@ -5415,18 +5416,58 @@ do_assemble_alias (tree decl, tree target)
 }
 
 
+/* Compute the set of indentifier nodes that is generated by aliases
+   whose targets are reachable.  */
+
+static struct pointer_set_t *
+compute_visible_aliases (void)
+{
+  struct pointer_set_t *visible;
+  unsigned i;
+  alias_pair *p;
+  bool changed;
+
+  /* We have to compute the set of visible nodes including aliases
+     themselves.  */
+  visible = pointer_set_create ();
+  do
+    {
+      changed = false;
+      for (i = 0; VEC_iterate (alias_pair, alias_pairs, i, p); ++i)
+	{
+	  struct cgraph_node *fnode = NULL;
+	  struct varpool_node *vnode = NULL;
+	  fnode = cgraph_node_for_asm (p->target);
+	  vnode = (fnode == NULL) ? varpool_node_for_asm (p->target) : NULL;
+	  if ((fnode
+	       || vnode
+	       || pointer_set_contains (visible, p->target))
+	      && !pointer_set_insert (visible, DECL_ASSEMBLER_NAME (p->decl)))
+	    changed = true;
+	}
+    }
+  while (changed);
+
+  return visible;
+}
+
 /* Remove the alias pairing for functions that are no longer in the call
    graph.  */
 
 void
 remove_unreachable_alias_pairs (void)
 {
+  struct pointer_set_t *visible;
   unsigned i;
   alias_pair *p;
 
   if (alias_pairs == NULL)
     return;
 
+  /* We have to compute the set of visible nodes including aliases
+     themselves.  */
+  visible = compute_visible_aliases ();
+
   for (i = 0; VEC_iterate (alias_pair, alias_pairs, i, p); )
     {
       if (!DECL_EXTERNAL (p->decl))
@@ -5435,7 +5476,9 @@ remove_unreachable_alias_pairs (void)
 	  struct varpool_node *vnode = NULL;
 	  fnode = cgraph_node_for_asm (p->target);
 	  vnode = (fnode == NULL) ? varpool_node_for_asm (p->target) : NULL;
-	  if (fnode == NULL && vnode == NULL)
+	  if (!fnode
+	      && !vnode
+	      && !pointer_set_contains (visible, p->target))
 	    {
 	      VEC_unordered_remove (alias_pair, alias_pairs, i);
 	      continue;
@@ -5444,6 +5487,8 @@ remove_unreachable_alias_pairs (void)
 
       i++;
     }
+
+  pointer_set_destroy (visible);
 }
 
 
@@ -5453,9 +5498,17 @@ remove_unreachable_alias_pairs (void)
 void
 finish_aliases_1 (void)
 {
+  struct pointer_set_t *visible;
   unsigned i;
   alias_pair *p;
 
+  if (alias_pairs == NULL)
+    return;
+
+  /* We have to compute the set of visible nodes including aliases
+     themselves.  */
+  visible = compute_visible_aliases ();
+
   FOR_EACH_VEC_ELT (alias_pair, alias_pairs, i, p)
     {
       tree target_decl;
@@ -5463,6 +5516,9 @@ finish_aliases_1 (void)
       target_decl = find_decl_and_mark_needed (p->decl, p->target);
       if (target_decl == NULL)
 	{
+	  if (pointer_set_contains (visible, p->target))
+	    continue;
+
 	  if (! (p->emitted_diags & ALIAS_DIAG_TO_UNDEF)
 	      && ! lookup_attribute ("weakref", DECL_ATTRIBUTES (p->decl)))
 	    {
@@ -5485,6 +5541,8 @@ finish_aliases_1 (void)
 	  p->emitted_diags |= ALIAS_DIAG_TO_EXTERN;
 	}
     }
+
+  pointer_set_destroy (visible);
 }
 
 /* Second pass of completing pending aliases.  Emit the actual assembly.