re PR c++/48481 (C++ overloading memory hog)

	PR c++/48481
	* name-lookup.c (struct arg_lookup): Add fn_set.
	(add_function): Check it.
	(lookup_arg_dependent_1): Initialize it.

From-SVN: r175732

2 files changed, 30 insertions, 7 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e95e7c8..42c21fe 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2011-06-30  Jason Merrill  <jason@redhat.com>
+
+	PR c++/48481
+	* name-lookup.c (struct arg_lookup): Add fn_set.
+	(add_function): Check it.
+	(lookup_arg_dependent_1): Initialize it.
+
 2011-06-29  Jason Merrill  <jason@redhat.com>
 
 	PR c++/49216
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 8bf5f5f..615e177 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -33,6 +33,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "debug.h"
 #include "c-family/c-pragma.h"
 #include "params.h"
+#include "pointer-set.h"
 
 /* The bindings for a particular name in a particular scope.  */
 
@@ -4864,6 +4865,7 @@ struct arg_lookup
   VEC(tree,gc) *namespaces;
   VEC(tree,gc) *classes;
   tree functions;
+  struct pointer_set_t *fn_set;
 };
 
 static bool arg_assoc (struct arg_lookup*, tree);
@@ -4883,16 +4885,11 @@ static bool arg_assoc_template_arg (struct arg_lookup*, tree);
 static bool
 add_function (struct arg_lookup *k, tree fn)
 {
-  /* We used to check here to see if the function was already in the list,
-     but that's O(n^2), which is just too expensive for function lookup.
-     Now we deal with the occasional duplicate in joust.  In doing this, we
-     assume that the number of duplicates will be small compared to the
-     total number of functions being compared, which should usually be the
-     case.  */
-
   if (!is_overloaded_fn (fn))
     /* All names except those of (possibly overloaded) functions and
        function templates are ignored.  */;
+  else if (k->fn_set && pointer_set_insert (k->fn_set, fn))
+    /* It's already in the list.  */;
   else if (!k->functions)
     k->functions = fn;
   else if (fn == k->functions)
@@ -5346,6 +5343,23 @@ lookup_arg_dependent_1 (tree name, tree fns, VEC(tree,gc) *args,
      picking up later definitions) in the second stage. */
   k.namespaces = make_tree_vector ();
 
+  /* We used to allow duplicates and let joust discard them, but
+     since the above change for DR 164 we end up with duplicates of
+     all the functions found by unqualified lookup.  So keep track
+     of which ones we've seen.  */
+  if (fns)
+    {
+      tree ovl;
+      /* We shouldn't be here if lookup found something other than
+	 namespace-scope functions.  */
+      gcc_assert (DECL_NAMESPACE_SCOPE_P (OVL_CURRENT (fns)));
+      k.fn_set = pointer_set_create ();
+      for (ovl = fns; ovl; ovl = OVL_NEXT (ovl))
+	pointer_set_insert (k.fn_set, OVL_CURRENT (ovl));
+    }
+  else
+    k.fn_set = NULL;
+
   if (include_std)
     arg_assoc_namespace (&k, std_node);
   arg_assoc_args_vec (&k, args);
@@ -5363,6 +5377,8 @@ lookup_arg_dependent_1 (tree name, tree fns, VEC(tree,gc) *args,
 
   release_tree_vector (k.classes);
   release_tree_vector (k.namespaces);
+  if (k.fn_set)
+    pointer_set_destroy (k.fn_set);
     
   return fns;
 }