re PR middle-end/46221 (huge number of c++ testsuite failures, libstdc++.so alias missing)

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.

From-SVN: r166479

gcc/ChangeLog

+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.
+
 2010-11-09  Nick Clifton  <nickc@redhat.com>
 
 	* config/mn10300/mn10300-modes.def: New file.

gcc/Makefile.in

@@ -2884,7 +2884,7 @@ varasm.o : varasm.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
    output.h $(TOPLEV_H) $(DIAGNOSTIC_CORE_H) xcoffout.h debug.h $(GGC_H) $(TM_P_H) \
    $(HASHTAB_H) $(TARGET_H) langhooks.h gt-varasm.h $(BASIC_BLOCK_H) \
    $(CFGLAYOUT_H) $(CGRAPH_H) targhooks.h tree-mudflap.h \
-   tree-iterator.h
+   tree-iterator.h pointer-set.h
 function.o : function.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_ERROR_H) \
    $(TREE_H) $(CFGLAYOUT_H) $(GIMPLE_H) $(FLAGS_H) $(FUNCTION_H) $(EXPR_H) \
    $(OPTABS_H) $(LIBFUNCS_H) $(REGS_H) hard-reg-set.h insn-config.h $(RECOG_H) \

gcc/testsuite/ChangeLog

+2010-11-09  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/46221
+	* gcc.target/i386/alias-1.c: New testcase.
+
 2010-11-08  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/constexpr-sassert.C: New.

gcc/testsuite/gcc.target/i386/alias-1.c

+/* { dg-do compile } */
+
+int yum;
+void dessert (void) { ++yum; }
+extern void jelly (void) __attribute__ ((alias ("dessert"), weak));
+extern void wobbly (void) __attribute__ ((alias ("jelly"), weak));
+
+/* { dg-final { scan-assembler "wobbly" } } */
+/* { dg-final { scan-assembler "jelly" } } */

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.