[lto] tree.c: Introduce stdarg_p.

[Kazu Hirata <kazu at codesourcery dot com>]

Hi,

Attached is a patch to introduce stdarg_p.

In gcc, I find many instances of idiom

  (TYPE_ARG_TYPES (fntype) != 0
   && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
       != void_type_node));

This patch proposes to replace these with a simple function call to
improve readability and make it easier to transition to the
TREE_VEC-based TREE_ARG_TYPES by hiding implementation details of
TREE_ARG_TYPES.

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

p.s.
I'll work on remaining occurrences (mostly in non-i386 backends) after
this patch.

Kazu Hirata

2006-06-09  Kazu Hirata  <kazu@codesourcery.com>

	* tree.c (stdarg_p): New.
	* tree.h: Add a prototype for stdarg_p.
	* builtins.c (fold_builtin_next_arg): Call stdarg_p.
	* config/i386/i386.c (ix86_return_pops_args,
	ix86_setup_incoming_varargs): Likewise.
	* dwarf2out.c (gen_subprogram_die): Likewise.
	* function.c (allocate_struct_function): Likewise.

Index: builtins.c
===================================================================
--- builtins.c	(revision 114406)
+++ builtins.c	(working copy)
@@ -9524,9 +9524,7 @@ fold_builtin_next_arg (tree arglist)
 {
   tree fntype = TREE_TYPE (current_function_decl);
 
-  if (TYPE_ARG_TYPES (fntype) == 0
-      || (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
-	  == void_type_node))
+  if (!stdarg_p (fntype))
     {
       error ("%<va_start%> used in function with fixed args");
       return true;
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 114406)
+++ config/i386/i386.c	(working copy)
@@ -2623,10 +2623,7 @@ ix86_return_pops_args (tree fundecl, tre
         || lookup_attribute ("fastcall", TYPE_ATTRIBUTES (funtype)))
       rtd = 1;
 
-    if (rtd
-        && (TYPE_ARG_TYPES (funtype) == NULL_TREE
-	    || (TREE_VALUE (tree_last (TYPE_ARG_TYPES (funtype)))
-		== void_type_node)))
+    if (rtd && !stdarg_p (funtype))
       return size;
   }
 
@@ -4041,7 +4038,6 @@ ix86_setup_incoming_varargs (CUMULATIVE_
   rtx nsse_reg;
   int set;
   tree fntype;
-  int stdarg_p;
   int i;
 
   if (!TARGET_64BIT)
@@ -4056,14 +4052,11 @@ ix86_setup_incoming_varargs (CUMULATIVE_
   cfun->stack_alignment_needed = 128;
 
   fntype = TREE_TYPE (current_function_decl);
-  stdarg_p = (TYPE_ARG_TYPES (fntype) != 0
-	      && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
-		  != void_type_node));
 
   /* For varargs, we do not want to skip the dummy va_dcl argument.
      For stdargs, we do want to skip the last named argument.  */
   next_cum = *cum;
-  if (stdarg_p)
+  if (stdarg_p (fntype))
     function_arg_advance (&next_cum, mode, type, 1);
 
   if (!no_rtl)
Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 114406)
+++ dwarf2out.c	(working copy)
@@ -11797,7 +11797,7 @@ gen_subprogram_die (tree decl, dw_die_re
       if (fn_arg_types != NULL)
 	{
 	  /* This is the prototyped case, check for....  */
-	  if (TREE_VALUE (tree_last (fn_arg_types)) != void_type_node)
+	  if (stdarg_p (TREE_TYPE (decl)))
 	    gen_unspecified_parameters_die (decl, subr_die);
 	}
       else if (DECL_INITIAL (decl) == NULL_TREE)
Index: function.c
===================================================================
--- function.c	(revision 114406)
+++ function.c	(working copy)
@@ -3865,11 +3865,7 @@ allocate_struct_function (tree fndecl)
 
   current_function_returns_pointer = POINTER_TYPE_P (TREE_TYPE (result));
 
-  current_function_stdarg
-    = (fntype
-       && TYPE_ARG_TYPES (fntype) != 0
-       && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
-	   != void_type_node));
+  current_function_stdarg = fntype && stdarg_p (fntype);
 
   /* Assume all registers in stdarg functions need to be saved.  */
   cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE;
Index: tree.c
===================================================================
--- tree.c	(revision 114406)
+++ tree.c	(working copy)
@@ -7573,4 +7573,14 @@ empty_body_p (tree stmt)
   return true;
 }
 
+/* Return true if function type FNTYPE is a stdarg.  */
+
+bool
+stdarg_p (tree fntype)
+{
+  return (TYPE_ARG_TYPES (fntype) != 0
+	  && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
+	      != void_type_node));
+}
+
 #include "gt-tree.h"
Index: tree.h
===================================================================
--- tree.h	(revision 114406)
+++ tree.h	(working copy)
@@ -4125,6 +4125,7 @@ extern tree upper_bound_in_type (tree, t
 extern tree lower_bound_in_type (tree, tree);
 extern int operand_equal_for_phi_arg_p (tree, tree);
 extern bool empty_body_p (tree);
+extern bool stdarg_p (tree);
 
 /* In stmt.c */