PR middle-end/44206

	* g++.dg/torture/pr44206.C: New.
	* ipa.c (cgraph_remove_unreachable_nodes): Cleanup; check
	existence of refrences before removing the function.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@165569 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 112 insertions, 41 deletions

diff --git a/gcc/ipa.c b/gcc/ipa.c
index dcf1e9ac072..af71330765f 100644
--- a/gcc/ipa.c
+++ b/gcc/ipa.c
@@ -384,22 +384,31 @@ cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
 	}
       if (!node->aux)
 	{
+	  struct cgraph_edge *e;
+	  bool found = false;
+	  int i;
+	  struct ipa_ref *ref;
+
           node->global.inlined_to = NULL;
 	  if (file)
 	    fprintf (file, " %s", cgraph_node_name (node));
-	  if (!node->analyzed || !DECL_EXTERNAL (node->decl) || before_inlining_p)
-	    cgraph_remove_node (node);
-	  else
+	  /* See if there is reachable caller.  */
+	  for (e = node->callers; e && !found; e = e->next_caller)
+	    if (e->caller->reachable)
+	      found = true;
+	  for (i = 0; (ipa_ref_list_refering_iterate (&node->ref_list, i, ref)
+		       && !found); i++)
+	    if (ref->refering_type == IPA_REF_CGRAPH
+		&& ipa_ref_refering_node (ref)->reachable)
+	      found = true;
+	    else if (ref->refering_type == IPA_REF_VARPOOL
+		     && ipa_ref_refering_varpool_node (ref)->needed)
+	      found = true;
+
+	  /* If so, we need to keep node in the callgraph.  */
+	  if (found || node->needed)
 	    {
-	      struct cgraph_edge *e;
-
-	      /* See if there is reachable caller.  */
-	      for (e = node->callers; e; e = e->next_caller)
-		if (e->caller->reachable)
-		  break;
-
-	      /* If so, we need to keep node in the callgraph.  */
-	      if (e || node->needed)
+	      if (node->analyzed)
 		{
 		  struct cgraph_node *clone;
 
@@ -419,10 +428,10 @@ cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
 			node->clone_of->clones = node->next_sibling_clone;
 		      if (node->next_sibling_clone)
 			node->next_sibling_clone->prev_sibling_clone = node->prev_sibling_clone;
-#ifdef ENABLE_CHECKING
+    #ifdef ENABLE_CHECKING
 		      if (node->clone_of)
 			node->former_clone_of = node->clone_of->decl;
-#endif
+    #endif
 		      node->clone_of = NULL;
 		      node->next_sibling_clone = NULL;
 		      node->prev_sibling_clone = NULL;
@@ -430,13 +439,16 @@ cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
 		  else
 		    gcc_assert (!clone->in_other_partition);
 		  node->analyzed = false;
+		  changed = true;
 		  cgraph_node_remove_callees (node);
 		  ipa_remove_all_references (&node->ref_list);
 		}
-	      else
-		cgraph_remove_node (node);
 	    }
-	  changed = true;
+	  else
+	    {
+	      cgraph_remove_node (node);
+	      changed = true;
+	    }
 	}
     }
   for (node = cgraph_nodes; node; node = node->next)
@@ -581,6 +593,7 @@ ipa_discover_readonly_nonaddressable_vars (void)
 static bool
 cgraph_externally_visible_p (struct cgraph_node *node, bool whole_program, bool aliased)
 {
+  struct cgraph_node *alias;
   if (!node->local.finalized)
     return false;
   if (!DECL_COMDAT (node->decl)
@@ -595,6 +608,23 @@ cgraph_externally_visible_p (struct cgraph_node *node, bool whole_program, bool
   /* If linker counts on us, we must preserve the function.  */
   if (cgraph_used_from_object_file_p (node))
     return true;
+  if (DECL_PRESERVE_P (node->decl))
+    return true;
+  if (lookup_attribute ("externally_visible", DECL_ATTRIBUTES (node->decl)))
+    return true;
+
+  /* See if we have linker information about symbol not being used or
+     if we need to make guess based on the declaration.
+
+     Even if the linker clams the symbol is unused, never bring internal
+     symbols that are declared by user as used or externally visible.
+     This is needed for i.e. references from asm statements.   */
+  for (alias = node->same_body; alias; alias = alias->next)
+    if (alias->resolution != LDPR_PREVAILING_DEF_IRONLY)
+      break;
+  if (!alias && node->resolution == LDPR_PREVAILING_DEF_IRONLY)
+    return false;
+
   /* When doing link time optimizations, hidden symbols become local.  */
   if (in_lto_p
       && (DECL_VISIBILITY (node->decl) == VISIBILITY_HIDDEN
@@ -626,11 +656,70 @@ cgraph_externally_visible_p (struct cgraph_node *node, bool whole_program, bool
 	      return true;
 	}
     }
-  if (DECL_PRESERVE_P (node->decl))
-    return true;
+
   if (MAIN_NAME_P (DECL_NAME (node->decl)))
     return true;
-  if (lookup_attribute ("externally_visible", DECL_ATTRIBUTES (node->decl)))
+
+  return false;
+}
+
+/* Return true when variable VNODE should be considered externally visible.  */
+
+static bool
+varpool_externally_visible_p (struct varpool_node *vnode, bool aliased)
+{
+  struct varpool_node *alias;
+  if (!DECL_COMDAT (vnode->decl) && !TREE_PUBLIC (vnode->decl))
+    return false;
+
+  /* Do not even try to be smart about aliased nodes.  Until we properly
+     represent everything by same body alias, these are just evil.  */
+  if (aliased)
+    return true;
+
+  /* If linker counts on us, we must preserve the function.  */
+  if (varpool_used_from_object_file_p (vnode))
+    return true;
+
+  if (DECL_PRESERVE_P (vnode->decl))
+    return true;
+  if (lookup_attribute ("externally_visible",
+			DECL_ATTRIBUTES (vnode->decl)))
+    return true;
+
+  /* See if we have linker information about symbol not being used or
+     if we need to make guess based on the declaration.
+
+     Even if the linker clams the symbol is unused, never bring internal
+     symbols that are declared by user as used or externally visible.
+     This is needed for i.e. references from asm statements.   */
+  if (varpool_used_from_object_file_p (vnode))
+    return true;
+  for (alias = vnode->extra_name; alias; alias = alias->next)
+    if (alias->resolution != LDPR_PREVAILING_DEF_IRONLY)
+      break;
+  if (!alias && vnode->resolution == LDPR_PREVAILING_DEF_IRONLY)
+    return false;
+
+  /* When doing link time optimizations, hidden symbols become local.  */
+  if (in_lto_p
+      && (DECL_VISIBILITY (vnode->decl) == VISIBILITY_HIDDEN
+	  || DECL_VISIBILITY (vnode->decl) == VISIBILITY_INTERNAL)
+      /* Be sure that node is defined in IR file, not in other object
+	 file.  In that case we don't set used_from_other_object_file.  */
+      && vnode->finalized)
+    ;
+  else if (!flag_whole_program)
+    return true;
+
+  /* Do not attempt to privatize COMDATS by default.
+     This would break linking with C++ libraries sharing
+     inline definitions.
+
+     FIXME: We can do so for readonly vars with no address taken and
+     possibly also for vtables since no direct pointer comparsion is done.
+     It might be interesting to do so to reduce linking overhead.  */
+  if (DECL_COMDAT (vnode->decl) || DECL_WEAK (vnode->decl))
     return true;
   return false;
 }
@@ -786,27 +875,9 @@ function_and_variable_visibility (bool whole_program)
       if (!vnode->finalized)
         continue;
       if (vnode->needed
-	  && (DECL_COMDAT (vnode->decl) || TREE_PUBLIC (vnode->decl))
-	  && (((!whole_program
-	        /* We can privatize comdat readonly variables whose address is
-		   not taken, but doing so is not going to bring us
-		   optimization oppurtunities until we start reordering
-		   datastructures.  */
-		|| DECL_COMDAT (vnode->decl)
-		|| DECL_WEAK (vnode->decl))
-	       /* When doing linktime optimizations, all hidden symbols will
-		  become local.  */
-	       && (!in_lto_p
-		   || (DECL_VISIBILITY (vnode->decl) != VISIBILITY_HIDDEN
-		       && DECL_VISIBILITY (vnode->decl) != VISIBILITY_INTERNAL)
-		   /* We can get prevailing decision in other object file.
-		      In this case we do not sed used_from_object_file.  */
-		   || !vnode->finalized))
-	      || DECL_PRESERVE_P (vnode->decl)
-              || varpool_used_from_object_file_p (vnode)
-	      || pointer_set_contains (aliased_vnodes, vnode)
-	      || lookup_attribute ("externally_visible",
-				   DECL_ATTRIBUTES (vnode->decl))))
+	  && varpool_externally_visible_p
+	      (vnode, 
+	       pointer_set_contains (aliased_vnodes, vnode)))
 	vnode->externally_visible = true;
       else
         vnode->externally_visible = false;