[PATCH][C++] Fix dump-file corruption

[Richard Guenther <rguenther at suse dot de>]

Hi!

Currently cxx_printable_name caches names in a ring in a non-lru
fashion.  This causes f.i. the ipa-inline dump to have corrupted
lines like

Considering int& Node<Dom, OrigDom>::affinity() [with Dom = Range<2>, 
OrigDom = Interval<2>] with 0 insns to be inlined into 
360'270^X^U@outBaseViewData<Dim, Dim2, L>::computeS
ubdomains() const [with int Dim = 2, int Dim2 = 2, L = 
UniformGridLayout<200

valgrind happily shows we're reading from freed memory.

The failure situation is simple.  Consider printing "%s %s" with
two different decl's and the first decl's name in the ring at the
position where we'll insert the second decl's name and free the firsts
one -> *kaboom* (independent of ring size).

Fixed by moving (swapping) a cached decls name to the position it would
have had if it had been freshly allocated.  This ensures that we can
reliably print strings with at least RING_SIZE decl names in them.

Ok for mainline?

Thanks,
Richard.

:ADDPATCH c++:

2005-10-05  Richard Guenther  <rguenther@suse.de>

	* tree.c (cxx_printable_name): Swap cached entry to head
	of the ring before returning it.

Index: cp/tree.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/tree.c,v
retrieving revision 1.443
diff -c -3 -p -r1.443 tree.c
*** cp/tree.c	2 Oct 2005 21:28:49 -0000	1.443
--- cp/tree.c	5 Oct 2005 15:26:52 -0000
*************** cxx_printable_name (tree decl, int v)
*** 886,899 ****
        || DECL_LANG_SPECIFIC (decl) == 0)
      return lang_decl_name (decl, v);
  
    /* See if this print name is lying around.  */
    for (i = 0; i < PRINT_RING_SIZE; i++)
      if (decl_ring[i] == decl)
!       /* yes, so return it.  */
!       return print_ring[i];
! 
!   if (++ring_counter == PRINT_RING_SIZE)
!     ring_counter = 0;
  
    if (current_function_decl != NULL_TREE)
      {
--- 886,910 ----
        || DECL_LANG_SPECIFIC (decl) == 0)
      return lang_decl_name (decl, v);
  
+   if (++ring_counter == PRINT_RING_SIZE)
+     ring_counter = 0;
+ 
    /* See if this print name is lying around.  */
    for (i = 0; i < PRINT_RING_SIZE; i++)
      if (decl_ring[i] == decl)
!       {
!         /* yes, so return it, but swap entries to have this one
! 	   freed last.  */
! 	tree decl_tmp;
! 	char *print_tmp;
! 	decl_tmp = decl_ring[ring_counter];
! 	decl_ring[ring_counter] = decl_ring[i];
! 	decl_ring[i] = decl_tmp;
! 	print_tmp = print_ring[ring_counter];
! 	print_ring[ring_counter] = print_ring[i];
! 	print_ring[i] = print_tmp;
!         return print_ring[ring_counter];
!       }
  
    if (current_function_decl != NULL_TREE)
      {