Question about GTY machinery (cgraph_edge)

[Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>]

Hi!

struct cgraph_edge is currently member of two lists, i.e.
it contains two "next" pointers, but is annotated like

struct cgraph_edge GTY((chain_next ("%h.next_caller")))
{
  struct cgraph_node *caller;
  struct cgraph_node *callee;
  struct cgraph_edge *next_caller;
  struct cgraph_edge *next_callee;
  tree call_expr;
  PTR GTY ((skip (""))) aux;
  /* When NULL, inline this call.  When non-NULL, points to the
explanation
     why function was not inlined.  */
  const char *inline_failed;
};

Is it possible and beneficial to have both next pointers
annotated with chain_next?  The internals documentation doesn't
say anything about this.  For optimization purposes, the
cgraph_node where the edges are hanging from has:

struct cgraph_node GTY((chain_next ("%h.next"), chain_prev
("%h.previous")))
{
  tree decl;
  struct cgraph_edge *callees;
  struct cgraph_edge *callers;
  struct cgraph_node *next;
...

i.e. callees first - would it the be beneficial to chain
the callee list in the edge structure to not have the marker
recursively go down this list first?

Thanks,
Richard.

--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/