[lto] Add nth_parm_type_p, alloc_parm_types, vec_heap2parm_types.

[Kazu Hirata <kazu at codesourcery dot com>]

Hi,

Attached is a patch to add three new functions.

At some places, we need write access to members of TYPE_ARG_TYPES.
With nth_parm_type_p, we can do:

  *(nth_parm_type_p (parm_types, 3)) = some_type;

So far, I've been addressing consumers of TYPE_ARG_TYPES, but there
are producers, too.  For those, we can use alloc_parm_types to
allocate parm_types filled with NULL.

Fianlly, this patch introduces vec_heap2parm_types.  This new function
is useful in a function like build_function_type_list, which takes a
variable number of parameters to specify a parameter type list, we
need to put those parameters into a VEC first and then convert that to
a TREE_VEC since TREE_VEC cannot grow on the fly.

To simplify the review process, this patch does not add any use of the
new functions except the use of nth_parm_type_p in
vec_heap2parm_types.

Tested on x86_64-pc-linux-gnu.  OK to apply?

Kazu Hirata

2006-07-16  Kazu Hirata  <kazu@codesourcery.com>

	* tree.c (nth_parm_type_p, alloc_parm_types,
	vec_heap2parm_types): New.
	* tree.h: Add prototypes to the new functions.

Index: tree.c
===================================================================
--- tree.c	(revision 115414)
+++ tree.c	(working copy)
@@ -1587,6 +1587,56 @@ nth_parm_type (tree parmtypes, int n)
   return TREE_VALUE (parmtypes);
 }
 
+/* Return the pointer to the Nth element of PARMTYPES, a list of
+   parameter types.  */
+
+tree *
+nth_parm_type_p (tree parmtypes, int n)
+{
+  while (n--)
+    {
+      gcc_assert (parmtypes);
+      parmtypes = TREE_CHAIN (parmtypes);
+    }
+
+  gcc_assert (parmtypes);
+  return &(TREE_VALUE (parmtypes));
+}
+
+/* Allocate parameter types of length LEN.  */
+
+tree
+alloc_parm_types (int len)
+{
+  tree t = NULL;
+
+  while (len--)
+    t = tree_cons (NULL, NULL, t);
+
+  return t;
+}
+
+/* Make a parameter list containing types given in V.  Return NULL if
+   V is empty.  */
+
+tree
+vec_heap2parm_types (VEC(tree,heap) *v)
+{
+  tree parm_types = NULL_TREE;
+
+  if (!VEC_empty (tree, v))
+    {
+      tree t;
+      int i;
+
+      parm_types = alloc_parm_types (VEC_length (tree, v));
+      for (i = 0; VEC_iterate (tree, v, i, t); i++)
+	*(nth_parm_type_p (parm_types, i)) = t;
+    }
+
+  return parm_types;
+}
+
 /* Returns the number of FIELD_DECLs in TYPE.  */
 
 int
Index: tree.h
===================================================================
--- tree.h	(revision 115414)
+++ tree.h	(working copy)
@@ -4162,6 +4162,9 @@ extern bool more_call_expr_args_p (const
 extern int call_expr_nargs (tree);
 extern tree call_expr_arg (tree, int);
 extern tree *call_expr_argp (tree, int);
+extern tree *nth_parm_type_p (tree, int);
+extern tree alloc_parm_types (int);
+extern tree vec_heap2parm_types (VEC(tree,heap) *);
 
 
 /* In stmt.c */