[PATCH] GTY chain_next annotate gimple_statement_base

[Richard Guenther]

This creates better marking code (even though we probably tail-recurse
for the exising one).

Bootstrapped and tested on x86-64-unknown-linux-gnu, applied.

Richard.

2012-08-20  Richard Guenther  <rguent...@suse.de>

        * gimple.h (gimple_statement_base): Annotate with GTY chain_next.

Index: gcc/gimple.h
===================================================================
--- gcc/gimple.h        (revision 190523)
+++ gcc/gimple.h        (working copy)
@@ -151,7 +151,7 @@ typedef struct
 /* Data structure definitions for GIMPLE tuples.  NOTE: word markers
    are for 64 bit hosts.  */
 
-struct GTY(()) gimple_statement_base {
+struct GTY((chain_next ("%h.next"))) gimple_statement_base {
   /* [ WORD 1 ]
      Main identifying code for a tuple.  */
   ENUM_BITFIELD(gimple_code) code : 8;