[PATCH,c++] make add_builtin_candidates use VECs

[Nathan Froyd <froydnj at codesourcery dot com>]

This patch makes add_builtin_candidates use VECs instead of TREE_LISTs
for keeping track of the argument types.  Slightly more space efficient,
less TREE_LIST usage, etc.

Tested on x86_64-unknown-linux-gnu, libstdc++ and g++ testsuites.  OK to
commit?

-Nathan

	* call.c (add_builtin_candidates): Use VECs for local variable
	`types'.  Adjust remainder of function accordingly.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index fbf98f1..71297ec 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -2328,12 +2328,11 @@ add_builtin_candidates (struct z_candidate **candidates, enum tree_code code,
 {
   int ref1, i;
   int enum_p = 0;
-  tree type, argtypes[3];
+  tree type, argtypes[3], t;
   /* TYPES[i] is the set of possible builtin-operator parameter types
-     we will consider for the Ith argument.  These are represented as
-     a TREE_LIST; the TREE_VALUE of each node is the potential
-     parameter type.  */
-  tree types[2];
+     we will consider for the Ith argument.  */
+  VEC(tree,gc) *types[2];
+  unsigned ix;
 
   for (i = 0; i < 3; ++i)
     {
@@ -2395,7 +2394,8 @@ add_builtin_candidates (struct z_candidate **candidates, enum tree_code code,
       ref1 = 0;
     }
 
-  types[0] = types[1] = NULL_TREE;
+  types[0] = make_tree_vector ();
+  types[1] = make_tree_vector ();
 
   for (i = 0; i < 2; ++i)
     {
@@ -2414,11 +2414,11 @@ add_builtin_candidates (struct z_candidate **candidates, enum tree_code code,
 	  if (code == COND_EXPR)
 	    {
 	      if (real_lvalue_p (args[i]))
-		types[i] = tree_cons
-		  (NULL_TREE, build_reference_type (argtypes[i]), types[i]);
+		VEC_safe_push (tree, gc, types[i],
+			       build_reference_type (argtypes[i]));
 
-	      types[i] = tree_cons
-		(NULL_TREE, TYPE_MAIN_VARIANT (argtypes[i]), types[i]);
+	      VEC_safe_push (tree, gc, types[i],
+			     TYPE_MAIN_VARIANT (argtypes[i]));
 	    }
 
 	  else if (! convs)
@@ -2434,54 +2434,60 @@ add_builtin_candidates (struct z_candidate **candidates, enum tree_code code,
 		continue;
 
 	      if (code == COND_EXPR && TREE_CODE (type) == REFERENCE_TYPE)
-		types[i] = tree_cons (NULL_TREE, type, types[i]);
+		VEC_safe_push (tree, gc, types[i], type);
 
 	      type = non_reference (type);
 	      if (i != 0 || ! ref1)
 		{
 		  type = TYPE_MAIN_VARIANT (type_decays_to (type));
 		  if (enum_p && TREE_CODE (type) == ENUMERAL_TYPE)
-		    types[i] = tree_cons (NULL_TREE, type, types[i]);
+		    VEC_safe_push (tree, gc, types[i], type);
 		  if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type))
 		    type = type_promotes_to (type);
 		}
 
-	      if (! value_member (type, types[i]))
-		types[i] = tree_cons (NULL_TREE, type, types[i]);
+	      if (! vec_member (type, types[i]))
+		VEC_safe_push (tree, gc, types[i], type);
 	    }
 	}
       else
 	{
 	  if (code == COND_EXPR && real_lvalue_p (args[i]))
-	    types[i] = tree_cons
-	      (NULL_TREE, build_reference_type (argtypes[i]), types[i]);
+	    VEC_safe_push (tree, gc, types[i],
+			   build_reference_type (argtypes[i]));
 	  type = non_reference (argtypes[i]);
 	  if (i != 0 || ! ref1)
 	    {
 	      type = TYPE_MAIN_VARIANT (type_decays_to (type));
 	      if (enum_p && UNSCOPED_ENUM_P (type))
-		types[i] = tree_cons (NULL_TREE, type, types[i]);
+		VEC_safe_push (tree, gc, types[i], type);
 	      if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type))
 		type = type_promotes_to (type);
 	    }
-	  types[i] = tree_cons (NULL_TREE, type, types[i]);
+	  VEC_safe_push (tree, gc, types[i], type);
 	}
     }
 
   /* Run through the possible parameter types of both arguments,
      creating candidates with those parameter types.  */
-  for (; types[0]; types[0] = TREE_CHAIN (types[0]))
+  FOR_EACH_VEC_ELT_REVERSE (tree, types[0], ix, t)
     {
-      if (types[1])
-	for (type = types[1]; type; type = TREE_CHAIN (type))
+      unsigned jx;
+      tree u;
+
+      if (!VEC_empty (tree, types[1]))
+	FOR_EACH_VEC_ELT_REVERSE (tree, types[1], jx, u)
 	  add_builtin_candidate
-	    (candidates, code, code2, fnname, TREE_VALUE (types[0]),
-	     TREE_VALUE (type), args, argtypes, flags);
+	    (candidates, code, code2, fnname, t,
+	     u, args, argtypes, flags);
       else
 	add_builtin_candidate
-	  (candidates, code, code2, fnname, TREE_VALUE (types[0]),
+	  (candidates, code, code2, fnname, t,
 	   NULL_TREE, args, argtypes, flags);
     }
+
+  release_tree_vector (types[0]);
+  release_tree_vector (types[1]);
 }